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6 I 7 I:ive-galloii Carboy fume-trap
6 I 8 80*C Heating bath
6 1.9 Colorimeter equipped with 50 mm tubular (low cell and 630 urn filters
6! 10 Recorder equipped with range expander
6 111 Vacuum pump
7 Reagents
7.1 Distilled water: Special precaution must be taken to insure that distilled water is free or
ammonia. Such water is prepared by passage of distilled water through an ion exchange
column comprised of a mixture of both strongly acidic cation and strongly basic anion
exchange resins. Furthermore, since organic contamination may interfere with this
analysis, use of the resin Dowex XE-75 or equivalent which also tends to remove organic
impurities is advised. The regeneration of the ion exchange column should be carried out
according to the instruction of the manufacturer.
NOTE 1: All solutions must be made using ammonia-free water.
7.2 Sulfuric acid: As it readily absorbs ammonia, special precaution must also be taken with
respect to its use. Do not store bottles reserved for this determination in areas of potential
ammonia contamination.
7.3 EDTA (2% solution): Dissolve 20 g disodium ethylenediamine tetraacetate in 1 liter of
distilled water. Adjust pH to 10.5-11 with NaOH (7.4).
7.4 Sodium hydroxide (30% solution): Dissolve 300 g NaOH in 1 liter of distilled water.
NOTE 2: The 30% sodium hydroxide should be sufficient to neutralize the digestate. In
rare cases it may be necessary to increase the concentration of sodium hydroxide in this
solution to insure neutralization of the digested sample in the manifold at the water
jacketed mixing coil.
7.5 Sodium nitroprusside, (0.05% solution): Dissolve 0.5 g Na,Fe(CN)jNO*2HiO in 1 liter
distilled water.
7.6 Alkaline phenol reagent: Pour 550 ml liquid phenol (88-90%) slowly with mixing into 1
liter of 40% (400 g per liter) NaOH. Cool and dilute to 2 liters with distilled water.
7.7 Sodium hypochlorite (1% solution): Dilute commercial "Ctorox'-200 ml to 1 liter with
distilled water. Available chlorine level should be approximately 1%. Due to the
instability of this product, storage over an extended period should be avoided.
7.8 Digestant mixture: Place 2 g red HgO in a 2 liter container. Slowly add, with stirring, 300
ml of acid water (100 ml H,S04 + 200 ml HjO) and stir until cool. Add 100 ml 10% (10
g per 100 ml) K2S04. Dilute to 2 liters with conc. sulfuric acid (approximately 500 ml at a
time, allowing time for cooling) Allow 4 hours for the precipitate to settle or filter
through glass fiber filter.
7.9 Stock solution: Dissolve 4.7193 gof pre-dned (I hour at 105*C) ammonium sulfate in
distilled water and dilute to 1.0 liter in a volumetric flask. 1.0 ml = I.OmgN.
7.10 Standard solution: Dilute 10 0 ml of stock solution (7.9) to 1000 ml. 1.0 ml = 0.01 mg N
7 11 Using the standard solution (1 10) prepare the following standards in 100 ml volumetric
flasks
351 I-?
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DRAFT
<_oiu in); N/i mi) MjiuI.hi/ 'iolutnm/liX) ml
0 00
00
0 05
05
0 10
1 0
0 20
20
0 40
40
060
60
0 80
8.0
1.00
10 0
1.50
15.0
2.00
20.0
Procedure
8.1 Set up manifolds as shown in Figures 1,2, and 3.
8.1.1 In the operation of manifold No. 1, the control of four key factors is required to
enable manifold No. 2 to receive the mandatory representative feed. First, the
digestant flowing into the pulse chamber (PC-1) must be bubble free; otherwise, air
will accumulate in A.-7, thus altering the ratio of sample to digestant in digestor.
Second, in maintaining even flow from the digestor helix, the peristaltic pump must
be adjusted-to cope with differences in density of the digestate and the wash water.
Third, the sample pick-up rate from the helix must be precisely adjusted to insure
that the entire sample is aspirated into the mixing chamber. And finally, the
contents of the "Mixing Chamber" must be kept homogeneous by the proper
adjustment of the air bubbling rate.
8.1.2 In the operation of manifold No. 2, it is important in the neutralization of the
digested sample to adjust the concentration of the NaOH so that the waste from the
C-3 debubbler is slightly acid to Hydrion B paper.
8.1.3 The digestor temperature is 390*C for the first stage and 360*C for the second and
third stages.
8.2 Allow both colorimeter and recorder to warm up for 30 minutes. Run a baseline with all
reagents, feeding distilled water through the sample line. Adjust dark current and
operative opening on colorimeter to obtain stable baseline.
8.3 Set sampling rate of Sampler II at 20 samples per hour, using a sample to wash ratio of 1
to 2 (I minute sample, 2 minute wash)
8.4 Arrange various standards in sampler cups in order of increasing concentration
Complete loading of sampler tray with unknown samples
8.5 Switch sample line from distilled water to sampler and begin analysis
Calculation
9.1 Prepare standard curve by plotting peak heights of processed standards against
concentration values. Compute concentration of samples by comparing sample peak
heights with standard curve
? Am vim pli tit. 11 I i.is i l i in 11 hi k (I (. diu oil i .it khi t li.it Ics-- thin 10'" \>l t In s unpli.- run
I 11111TI I [l III ! \ |Mh 'I l i I I 1111, .1 111 I I'l till
351 1-3
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10 Precision and Accuracy
10 1 Stx laboratories analyzed four natural water samples containing exact increments of
organic nitrogen compounds, with the following results
Increment as Frecision as Accuracy as
Kjeldahl-Nitrogen
mg N/liter
Standard Deviation
Kjeldaht-N mg N/liter
Bias,
%
litas.
mg N/liter
1.89
0.54
-24.6
-0.46
2.18
0.61
-28.3
-0.62
5.09
1.25
-23.8
-1.21
5.81
1.B5
-21.9
-1.27
Bibliography
1. Kammerer, P. A., Rodel, M. G., Hughes, R. A., and Lee, G. F., "Low Level Kjeldahl Nitrogen
Determination on the Technicon AutoAnalyzer". Environmental Science and Technology, J_,
340(1967).
2. McDaniel, W. H., Hemphill, R. N., Donaldson, W. T.t "Automatic Determination of Total
Kjeldahl Nitrogen in Estuarine Waters". Presented at Technicon Symposium on Automation
in Analytical Chemistry, New York, October 3,1967.
3. B. O'Connor, Dobbs, Villiers, and Dean, "Laboratory Distillation of Municipal Waste
Effluents". JWPCF 39, R 25,1967.
351 1-4
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WASH WATER (TO SAMPLER 2)
SMALL
MIXING COIL
QQ.ML
COOLING WATER
VACUUM PUMP
;=(}
AO
PCI
t* IICESTII
PLAA AT A IT
PUMP
MIIIKt CHAMBER
LAR6E MIX INS
COIL
HUE
A
PIVE 8l»
¦ l/nli.
2.00 WISH WATER
.1.60 SAMPLE
.2.00 PI5TILLE-0 WATER
,1-60 AIR *
,203 D1BESTANT
2.03 DISESTAHT
:}
FOR SALT
WATER
SAMPLES
ACI0FLEI TUBING
.3.90 DISTILLED WATER
(3.90 DISTILLED WATER
PROPORTIONING PIMP
* AIR IS SCRUBBED THRU 5X H2S0<
* 'TEFLON TUBING OR GLASS
"•FOR FRESH WATER SAMPLES USE:
P B
J ,90 WASH WATER
P P
2.50 SAMPLE
G G
2.00 DISTILLED WATER
Y T
1.20 AIR
FIGURE 1. KJELDAHL NITROGEN - MANIFOLD 1 AA-I
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CONTINUOUS DIGESTER & MIXING CHAMBER ASSEMBLY
DILHTIOK WATEK
1Q ASPIRATOR
—
BLOWER
\
AOJVSTABLE FLOW
"REMIT FLARATART
PUMP
LIKE DESIGNATION:
1. OXIDIZED SAMPLE
2. All AGITATION
3. MIXING CHAMBER OVERFLOW
4. WASTE
All
HALf FILLED WITH
CONNECTED FO
TO SUMP
TO MANIFOLD NO. 2
FIGURE 2. KJELDAHL NITROGEN AA-I
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WASTE -*
ml/mis.
.MP SAMPLE FROM MIIIK6 CHAMBER
¦ »¦ |S£E "",F0U '
IIP 0 IS TILL E D WATEI
LUt ILU
JACKETED MIXEI
1.?8 AH
LARGE MIXING COILS |IH)
PQftQMftQ .MQftflftflft.
HI EDTA
l »» IISTILLE1 WATEI
1.11 ALL PMEM9L
1.21 »HCt
1.?l XITIIf IISSIBE
3.41 WASTE
SMALL MIXING COIL
P1IFIITIBNII6 PIMP
COIL
COLORIMETER
50mm TUBULAR f/c
638 *¦ FILTERS
FIGURE 3. KJELDAHL NITROGEN MANIFOLD 2. AA-I
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Fluoride -
Fluoride - Fluoride is detenmiend with an ion selective electrode
using EPA method 340.2. The method quotes a useful range of 0.1-1000
mg/L F. The method is able to detect F~ below 0.1 mg/L, but the
calibration curve becomes non-linear at about 0.01 mg/L.
Some of the lake samples are expected to contain low levels of fluoride
(<0.1 mg/L). In order to ensure accurate results, method 340.2 is
modified slightly in the following manner. Any sample which Is found to
contain less than 0.1 mg/L will be reanalyzed after spiking with 0.1 mg/L
F-. The sample result will then be estimated by subsequently subtracting
the 0.1 mg/L spike.
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6 Reagents
6.1 Buffer solution, pH 5.0-5.5: To approximately 500 ml of distilled water in a 1 liter beaker
add 57 ml of glacial acetic acid, 58 g of sodium chloride and 4 g of CDTA'2' Sur to
dissolve and cool to room temperature Adjust pH of solution to between 5.0 and 5.5 with
5 N sodium hydroxide (about 150 ml will be required). Transfer solution to a I liter
volumetric flask and dilute to the mark with distilled water. For work with brines,
additional NaCl should be added to raise the chloride level to twice the highest expected
level of chloride in the sample.
6.2 Sodium fluoride, stock solution: 1.0 ml = 0.1 mg F. Dissolve 0.2210 g of sodium fluoride
in distilled water and dilute to 1 liter in a volumetric flask. Store in chemical-resistant
glass or polyethylene.
6.3 Sodium fluoride, standard solution: 1.0 ml = 0.01 mg F. Dilute 100.0 ml of sodium
fluoride stock solution (6.2) to 1000 ml with distilled water.
6.4 Sodium hydroxide, 5N: Dissolve 200 g sodium hydroxide in distilled water, cool and
dilute to 1 liter.
7. Calibration
7.1 Prepare a series of standards using the fluoride standard solution (6.3) in the range of 0 to
2.00 mg/I by diluting appropriate volumes to 50.0 ml. The following series may be used:
Millimeters of Standard Concentration when Diluted
(1.0 ml «= 0.01 mg/F) to SO ml, mg F/liter
0.00
0.00
1.00
0.20
2.00
0.40
3.00
0.60
4.00
0.80
5.00
1.00
6.00
1.20
8.00
1.60
10.00
2.00
7.2 Calibration of Electrometer Proceed as described in (8.1). Using semilogarithmic graph
paper, plot the concentration of fluoride in mg/liter on the log axis vs. the electrode
potential developed in the standard on the linear axis, starting with the lowest
concentration at the bottom of the scale. Calibration of a selective ion meter: Follow the
directions of the manufacturer for the operation of the instrument
8. Procedure
8.1 Place 50.0 ml of sample or standard solution and 50.0 mi of buffer (See Note) in a 150 ml
beaker. Place on a magnetic stirrer and mix at medium speed. Immerse the electrodes in
the solution and observe the meter reading while mixing The electrodes must remain in
ihe solution for at least three minutes or until the reading has stabilized. Al
concentrations under 0 5 mg/liter F, it may require as long as five minutes to reach a
stable meter reading, high concentrations stabilize more quickly. If a pH meter is used,
record the potential measurement for each unknown sample and convert the potential
340 2-2
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reading to the fluoride ion concentration of the unknown using the standard cur -e. If a
selective ion meter is used, read the fluoride level in the unknown sample directly in
mg/1 on the fluoride scale
NOTE: For industrial waste samples, this amount of buffer may not be adequate
Analyst should check pH first, lfhighly basic (> 9), add 1 N HC1 to adjust pH to 8.3.
9 Precision and Accuracy
9.1 A synthetic sample prepared by the Analytical Reference Service, PHS, containing 0.85
mg/1 fluoride and no interferences was analyzed by 111 analysts; a mean of 0.84 mg/1
with a standard deviation of ±0.03 was obtained.
9.2 On the same study, a synthetic sample containing 0.75 mg/1 fluoride, 2.5 mg/l
polyphosphate and 300 mg/1 alkalinity, was analyzed by the same 111 analysts; a mean
of 0.7S mg/1 fluoride with a standard deviation of *0.036 was obtained.
Bibliography
1. Patent No. 3,431,182 (March 4,1969).
2. CDTA is (heabbreviated designation of I,2-cydohexyIenedinurilotetraaceticacid.(The
monohydrace form may also be used.) Eastman Kodak 15411, Mallinckrodt 2357, Sigma D
1383, Tridom-Fluka 32869-32870 or equivalent.
3. Standard Methods for the Examination of Water and Wastewaters, p 389, Method No. 414A,
Preliminary Distillation Step (Bellack), and p 391, Method No. 414B, Electrode Method, 14 th
Edition (1975).
4. Annual Book of ASTM Standards, Part 31, "Water", Standard D1179-72, Method B, p 312
(1976).
340.2-3
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Sulfate, Nitrate, Nitrite, and Chloride
This method is based on ion chromatographic methods in references 1 and 6.
CHLORIDE, NITRITE, NITRATE, AND SULPHATE DETERMINATION USING ION
CHROMATOGRAPHY
Scope and Application
This procedure Is based on the use of Dionex Ion Chromatographs. Other
systems nwy be used with minor modifications involving columns, chromato-
graphic conditions, and reagents. In these cases, follow the manufacturers
recommendations.
This procedure covers the determination of sulfate, nitrite, nitrate, and
chloride In water. The anions are separated on an 1on exchange column
because of their different affinities for the exchange material. The
material commonly used for anions is a polystyrene/divinyl benzene polymer
coated with quaternary ammonium active sites. After separation, the
anions pass through a cation exchange fiber suppressor column which
exchanges all cations for H+ ions. All species are detected as acids by a
conductivity meter.
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Any species with a retention time similar to that of the sought anions
will interfere. Lakewater should not contain such species.
All four anions should be adequately detected and resolved in about 10
minutes. Nitrite is not expected to be present, but will be quantified
if present.
Apparatus
1. Ion chromatograph (Dionex models 10, 12, 14, 16 or 2000 series) with
a S2 or S4 anion separator column and anion fiber suppressor column.
2. Optional - automated Injection system {commercially available, e.g.,
from Micromeretics, 611 son).
3. Data Recording System - Integrators or strip chart recorders can be
used for recording the ion chromatographs. The nominal output to the
recorder is 1.0 v. The Dionex plane parallel electrode conductivity
detector, however, gives a linear response with concentration until
electronic saturation occurs at approximately 4.0 v. Therefore,
several analytical ranges on recorders set at different full-scale
voltages can be monitored simultaneously.
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4. Cubitainers 4- and 20-liter.
5. Pipettes - an assortment of sizes.
6. Volumetric flasks - an assortment of sizes.
Reagents - All chemicals must be ACS Reagent Grade or better.
1. Deionized water - ASTM Type 1 Reagent Grade.
2. Concentrated Eluent, 0.6 M NaHC03/0.48 M Na2C03 - Dissolve 100.8407 g
NaHC03 and 101.7509 g Na2C03 in 2 liters of hot deionized water.
Store in a tightly sealed cubitainer, ensuring that no head space
exists.
3. Working Eluent, 0.003 M NaHC03/0.0024 M Na2C03 - Dilute 20-mL of
concentrated eluent (0.6 M NaHC03/0.48 M Na2C03) to 4 liters with
deionized water; transfer to a 4-liter cubitainer bag. (If a 20-liter
cubitainer used, dilute 100-ml concentrated eluent to 20 liters.)
4. Regenerant, 0.0025 N H2SO4 - Add 2.8 ml of conc. H2SO4 to approxi-
mately 3 liters of deionized water in a 4-liter plastic bottle; dilute to
4 liters.
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5. Mixed Stock Solution - 1000 mg/L S0^f 200 mg/L NO3" 200 mg/L
CL". Oissolve 0.3297 g NaCl, 0.3261g KNO3 and 1.8142 g K2S04 in
1 liter of deionized water.
6. Nitrite stock solution - 1000 mg/L N02~ Oissolve 1.4998 g NaN02
1n 1 liter of deionized water.
7. Standard Solution A - Dilute 10-mL of mixed stock solution to 100
mL with deionized water (100 mg/L SO^, 20 mg/L NO3", and 20 mg/L
CI").
8. Standard Solution B - Dilute 10-mL standard solution A to 100-mL with
deionized water (10 mg/L S0| 2 mg/L NOj", and 2 mg/L CI").
9. Standard Solution C - Dilute 1-mL of nitrite stock solution to
100 mL with deionized water (10 mg/L).
6.4 C.
10. Working Standards - Use standard solutions A B^jto prepare the
working standards listed in Table 6. These standards are prepared
by diluting the indicated volumes of standard solutions A, B or C to
100-mL with deionized water. The working standards are prepared
daily.
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TABLE 6.1 CONCENTRATION OF WORKING STANDAROS USED FOR THE ANALYSIS OF
WATER SAMPLES BY ION CHROMATOGRAPHY
Working
Standard
no;
Concentration in mg/L
SO,
Ci:
NOi
Milliliters of Standard
Solution A, B, or C per
100/mL of Working Standard
A
4
20
4
-
20-mL of A
B
1
5
1
-
5-mL of A
C
0.2
1
0.2
-
10-mL of B
D
0.1
0.5
0.1
-
5-mL of B
E
0.02
0.1
0.02
-
1-mL of B
F
-
-
1.0
0.5
5-mL of A + 5-mL
of C
G
-
-
1.0
0.1
5-mL of A + 1-mL
of C
H
-
-
1.0
0.05
5-mL of A + 5-mL
of C
Procedure
When an aqueous sample 1s Injected, the water passes rapidly through
both the separator and the suppressor columns, and gives rise to a very
low conductivity. This negative water dip can Interfere with the Cl-
analysis; thus It may be necessary to remove the water dip for low-level
Cl~ analysis by adding concentrated eluent to all samples and standards.
1. Pour each sample or standard into a clean plastic test tube to a
previously established 10-mL mark; pipette 50-uL of the concentrated
eluent into the test tube; seal the top with parafilm, and shake to
mix( 'I'v 1 ' 'l- .M- .''.j
i , \ • . ( • i . " . '" \ ; . ^ • i v\, , V ,, ^
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2. Operate the fiber suppressor as recommended by Dionex.
3. Set up the recorders or integrators for the most sensitive range and
for any additional ranges needed. Operate integrators following
manufacturer's instructions.
4. Recommendations for optimum Dionex sensitivity:
a. 0.003 M NaHC03/0.0024 M Na2C03 eluent with S2 or S4 anion
separator and fiber suppressor,
b. 3 iimho/cm full scale on recorder,
c. 0.8-ml injection loop,
d. Flow rate 2.3 mL/min,
e. Pressure gauge or similar device used as pump Stroke noise
suppressor (not necessary with 2000 series).
5. Pump the eluent through the columns. After a stable baseline is
obtained, inject the highest standard either manually or with the
autosampler. Adjust the recorder zero to approximately 10 percent
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of the chart; as the highest standard for S0| elutes, adjust the
recorder calibration to approximately 90 percent of the chart.
Reanalyze the standard and measure the NOj/SO^ resolution {fill
in the resolution test form). If the resolution does not exceed
60 percent, replace the separator column and start over.
Fill the autosampler with CI", NO3-, NO2", and So| calibration
standards, QC standards, analyst spikes, blanks, and samples,
starting with the lowest concentration standard and Increasing the
concentrations, or inject the samples manually 1n the same order.
Turn on the autosampler to start analyzing samples.
When the run Is complete, number the samples on the strip chart;
draw a baseline for each sample or standard; measure the peak height
with a clear plastic ruler; and record the peak height on the strip
chart and on a data form. If an integrator is used, record the peak
heights on a data form.
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Calculations
Using a Graph--
Construct calibration curves by plotting concentrations of standards
against the peak height for each analyte. Read the concentration of the
analyte directly from the calibration curves.
Using a Linear Least Squares Fit—
Equations used for calculation of the linear least squares fit are avail-
able in most elementary statistics books. The linear least squares fit
yields the following parameters: slope (m), intercept (b), error of fit
(e) and correlation coefficient (r). The slope and intercept define a
relationship between concentration of standard i () and the predicted
instrument response (y-j),
yj = mxj + b. (1)
A simple rearrangement of Equation 1 yields the concentration (x-j)
corresponding to an instrumental response of (yj),
Xj = (yj - b)/tn. (2)
Care and Maintenance of the IC - Follow manufacturer's recommendations.
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Dionet Resolution lest
Date
Concentration SO^ yig/ml. NOj pg/mt
Column Bach Pressure {at max ot stroke) pst
flow rate. mt/mm
Column Serial H: ; Oate of purchase.
Is precolumn in system? Yes No
(aI cm fbf cm (see Figure below)
Percentage Resolution: 100 * ft-a/b)
Test Chromaiogram:*
sof
FIGURE
'Cut out test chromaiogram and attach to this form
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CALCIUM
Method 215.1 (Atomic Absorption, direct aspiration)
STORET NO. Total 00916
Dissolved 00915
Optimum Concentration Range: 0.2-7 mg/1 using a wavelength of 422.7 nm
Sensitivity: 0.08 mg/1
Detection Limit: 0.01 mg/1
Preparation of Standard Solution
1. Stock Solution: Suspend 1.250 g of CaCOj (analytical reagent grade), dried at 180*Cfor 1
hour before weighing, in deionized distilled water and dissolve cautiously with a
minimum of dilute HC1. Dilute to 1000 ml with deionized distilled water. 1 ml = 0.5
mgCa (500 mg/1).
2. Lanthanum chloride solution: Dissolve 29 g of La}0:, slowly and in small portions, in
250 ml cone. HQ (Caution: Reaction is violent) and dilute to 500 ml with deionized
distilled water.
3. Prepare dilutions of the stock calcium solutions to be used as calibration standards at the
time of analysis. To each 10 ml volume of calibration standard and sample alike add 1.0
ml of the lanthanum chloride solution, i.e., 20 ml of standard or sample + 2 ml LaClj —
22 mL
Sample Preservation
I. For sample handling and preservation, see part 4.1 of the Atomic Absorption Methods
section of this manual.
Sample Preparation
1. For the analysis of total calcium in domestic and industrial effluents, the procedures for
the determination of total metals as given in parts 4.1.3 and 4.1.4 of the Atomic
Absorption Methods section of this manual have been found to be satisfactory.
2. For ambient waters, a representative aliquot of a well-mixed sample may be used directly
for analysis. If suspended solids are present in sufficient amounts to clog the nebulizer,
the sample may be allowed to settle and the supernatant liquid analyzed directly.
Instrumental Parameters (General)
1. Calcium hollow cathode lamp
2. Wavelength: 422.7 nm
Approved for NPDES
Issued 1971
Editorial revision 1974
215.1-1
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MAGNESIUM
Method 242.1 (Atomic Absorption, direct aspiration)
STORET NO. Total 00927
Dissolved 00925
Suspended 00926
Optimum Concentration Range: 0.02-0.5 mg/1 using a wavelength of285.2 nm
Sensitivity: 0.007 mg/1
Detection Limit: 0.001 mg/1
Preparation of Standard Solution
1. Stock Solution: Dissol ve 0.829 g of magnesium oxide, MgO (analytical reagent grade), in
10 ml of redistilled HNOj and dilute to 1 liter with deionized distilled water. 1 ml = 0.50
mgMg (500 mg/1).
2. Lanthanum chloride solution: Dissolve 29 g of La,Oj, slowly and in small portions in 250
ml conc. HQ, (Caution: Reaction is violent), and dilute to 500 ml with deionized distilled
water.
3. Prepare dilutions of the stock magnesium solution to be used as calibration standards at
the time of analysis. To each 10 ml volume of calibration standard and sample alike add
1.0 ml of the lanthanum chloride solution, i.e., 20 ml of standard or sample +2 ml LaCI,
= 22 ml.
Sample Preservation
1. For sample handling and preservation, see part 4.1 of the Atomic Absorption Methods
section of this manual
Sample Preparation
1. For the analysis of total magnesium in domestic and industrial effluents, the procedures
for the determination of total metals as given in parts 4.1.3 and 4.1.4 of the Atomic
Absorption Methods section of this manual have been found to be satisfactory.
2. For ambient waters, a representative aliquot of a well-mixed sample may be used directly
for analysis. If suspended solids are present in sufficient amounts to clog the nebulizer,
the sample may be allowed to settle and the supernatant liquid analyzed directly.
3. Samples should be preserved with (1:1) nitric acid to a pH of 2 at the time of collection.
Instrumental Parameters (General)
1. Magnesium hollow cathode lamp
2 Wavelength-285 2 nm
Approved for NPDES
Issued 1971
Editorial revision 1974 and 1978
242 l-l
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3. Fuel: Acetylene
4. Oxidant: Air
5. Type of flame: Oxidizing
Notes
1. The interference caused by aluminum at concentrations greater than 2 mg/1 is masked
by addition of lanthanum. Sodium, potassium and calcium cause no interference at
concentrations less than 400 mg/I.
2. The following line may also be used:
202.S nm Relative Sensitivity 25
3. To cover the range of magnesium values normally observed in surface waters (0.1-20
mg/1), it is suggested that either the 202.5 nm line be used or the burner head be rotated.
A 9Qr rotation of the burner head will produce approximately one-eighth the normal
sensitivity.
4. Data to be entered into STORET must be reported as mg/1.
5. The gravimetric method may also be used (Standard Methods, 14th Edition, p 221).
Precision and Accuracy
1. In a single laboratory (EMSL), using distilled water spiked at concentrations of 2.1 and
8.2 mg Mg/1 the standard deviations were ±0.1 and *0.2, respectively. Recoveries at
both of these levels were 100%.
24' 1-2
-------
8 4 For those instruments which do not read out directly in concentration, a calibration
curve is prepared to cover the appropriate concentration range Usually, this means the
preparation of standards which produce an absorption of 0 to 80 percent. The correct
method is to convert the percent absorption readings to absorbance and plot that value
against concentration. The following relationship is used to convert absorption values to
absorbance:
absorbance = log (100/%T) = 2-log % T
where %T = 100-% absorption
As the curves are frequently nonlinear, especially at high absorption values, the number
of standards should be increased in that portion of the curve.
8.5 Method of Standard Additions: In this method, equal volumes of sample are added to a
deionized distilled water blank and to three standards containing different known
amounts of the test element The volume of the blank and the standards must be the
same. The absorbance of each solution is determined and then plotted on the vertical axis
of a graph, with the concentrations of the known standards plotted on the horizontal
axis. When the resulting line is extrapolated back to zero absorbance, the point of
interception of the abscissa is the concentration of the unknown. The abscissa on the left
of the ordinate is scaled the same as on the right side, but in the opposite direction from
the ordinate. An example of a plot so obtained is shown in Fig. I.
o
c
a
a
J3
<
o
Zei
Abso
Concentration
Cone, of
Sample
flddn 0
No Addn
AddnI Addn 2 Addn 3
Addn of 50% Addn of 100% Addn of 150%
of Expected of Exptcted of Expected
Amount Amount Amount
FIGURE 1. STANDARD ADDITION PLOT
Mr.TALS-12
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Section 4.0
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MANGANESE
Method 243.1 (Atomic Absorption, direct aspiration)
STORET NO. Total 01055
Dissolved 01056
Suspended 01054
Optimum Concentration Range: 0.1-3 mg/1 using a wavelength of279.5 nm
Sensitivity: 0.05 mg/1
Detection Limit: 0.01 mg/1
Preparation of Standard Solution
L Stock Solution: Carefully weigh 1.000 g of manganese metal (analytical reagent grade)
and dissolve in 10 ml of redistilled HNOj. When solution is complete, dilute to 1 liter
with 1% (V/V) HC1.1 ml = 1 mg Mn (1000 mg/1).
2. Prepare dilutions of the stock solution to be used as calibration standards at the time of
analysis. The calibration standards should be prepared using the same type of acid and at
the same concentration as will result in the sample to be analyzed either directly or after
processing.
Sample Preservation
1. For sample handling and preservation, see part 4.1 of the Atomic Absorption Methods
section of this manual.
Sample Preparation
1. The procedures for preparation of the sample as given in parts 4.1.1 thru 4.1.4 of the
Atomic Absorption Methods section of this manual have been found to be satisfactory.
Instrumental Parameters (General)
1. Manganese hollow cathode lamp
2. Wavelength: 279.5 nm
3. Fuel: Acetylene
4. Oxidant: Air
5. Type of flame: Oxidizing
Analysis Procedure
1. For analysis procedure and calculation, see "Direct Aspiration", part 9.1 of the Atomic
Absorption Methods section of this manual.
Approved for NI'DES
Issued 1971
Editorial revision 1974 and 1978
243 l-l
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Notes
1. For levels of manganese below 25 ug/l, either the furnace procedure, Method 243.2, or
the Special Extraction Procedure given in part 9 2 of the Atomic Absorption Methods
section is recommended. The extraction is earned out at a pH of 4.5 to 5. The manganese
chelate is very unstable and the analysis must be made without delay to prevent tis re-
solution in the aqueous phase.
2. The following line may also be used:
403.1 nm Relative Sensitivity 10.
3. Data to be entered into STORET must be reported as irg/1.
4. The persulfate colorimetric method may also be used (Standard Methods, 14th Edition,
P 225).
Precision and Accuracy
1. An interlaboratory study on trace metal analyses by atomic absorption was conducted by
the Quality Assurance and Laboratory Evaluation Branch of EMSL. Six synthetic
concentrates containing varying levels of aluminum, cadmium, chromium, copper, iron,
manganese, lead and zinc were added to natural water samples. The statistical results for
manganese were as follows:
Standard
Number True Values Mean Value Deviation Accuracy as
of Labs ug/Iiter ug/liter ug/liter % Bias
77 426 432 70 1,5
78 469 474 97 1.2
71 84 86 26 2.1
70 106 104 31 -2.1
55 11 21 27 93
55 17 21 20 22
243 1-2
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POTASSIUM
Method 258.1 (Atomic Absorption, direct aspiration)
STORET NO. Total 00937
Dissolved 00935
Suspended 00936
Optimum Concentration Range: 0.1-2 mg/l using a wavelength of 766.5 nm
Sensitivity: 0.04 mg/l
Detection Limit: 0.01 mg/l
Preparation of Standard Solution
1. Stock Solution: Dissolve 0.1907 g of KC1 (analytical reagent grade), dried at 1 i(TC, in
deionized distilled water and make up to 1 liter. 1 ml = 0.10mgK(100mg/l).
2. Prepare dilutions of the stock solution to be used as calibration standards at the time of
analysis. The calibration standards should be prepared using the same type of add and at
Che same concentration as will result in the sample to be analyzed-either directly or after
processing.
Sample Preservation
1. For sample handling and preservation, see part 4.1 of the Atomic Absorption Methods
section of this manual.
Sample Preparation
1. For the analysis of total potassium in domestic and industrial effluents, the procedures
for the determination of total metals as given in parts 4.1.3 and 4.1.4 of the Atomic
Absorption Methods section of this manual have been found to be satisfactory.
2. For ambient waters, a representative aliquot of a well mixed sample may also be used
directly for analysis. If suspended solids are present in sufficient amounts to clog the
nebulizer, the sample may be allowed to settle and the supernatant liquid analyzed
directly.
Instrumental Parameters (General)
1. Potassium hollow cathode lamp
2. Wavelength: 766.5 nm
3. Fuel: Acetylene
4. Oxidant: Air
5 Typcofflame Slightly oxidizing
Approved for NPDES
Issued 1971
Editorial revision 1974
258 M
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Analysis Procedure
t. For the analysis procedure and the calculation. ice "Direct Aspiration", part 9.1 of the
Atomic Absorption Methods section oF this manual
Notes
1. In air-acetylene or other high temperature flames ( > 28Q0"C), potassium can experience
partial ionization which indirectly affects absorption sensitivity. The presence of other
alkali salts in the sample can reduce this ionization and thereby enhance analytical
results. The ionization suppressive effect of sodium is small if the ratio of Na to K is
under 10. Any enhancement due to sodium can be stabilized by adding excess sodium
(1000 ug/ml) to both sample and standard solutions. If more stringent control of
ionization is required, the addition of cesium should be considered. Reagent blanks
should be analyzed to correct for potassium impurities in the buffer stock.
2. The 404.4 nm line may also be used. This line has a relative sensitivity of500.
3. To cover the range of potassium values normally observed in surface waters (0.1-20
mg/1), it is suggested that the burner head be rotated. A 90* rotation of the burner head
provides approximately one-eighth the normal sensitivity.
4. The flame photometric or colorimetric methods may also be used (Standard Methods,
14th Edition, p 234 & 235).
5. Data to be entered into STORET must be reported as mg/1.
Precision and Accuracy
I. In a single laboratory (EMSL), using distilled water samples spiked at concentrations of
1.6 and 6.3 m§ K/l. The standard deviations were ±0.2 and *0.5, respectively.
Recoveries at these levels were 103% and 102%, respectively.
258 1-2
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SODIUM
Method 273.1 (Atomic Absorption, direct aspiration)
STORET NO. Total 00929
Dissolved 00930
Suspended 00928
Optimum Concentration Range: 0.03-1 mg/I using a wavelength of 5S9.6 nm
Sensitivity: 0.015 mg/I
Detection Limit: 0.002 mg/I
Preparation of Standard Solutions
1. Stock Solution: Dissolve 2.542 g of NaCI (analytical reagent grade), dried at 140*C, in
deionized distilled water and make up to I liter. I ml = 1 mgNa(l000mg/l).
2. Prepare dilutions of the stock solution to be used as calibration standards at the time of
analysis. The calibration standards should be prepared using the same type of acid and at
the same concentration as will result in the sample to be analyzed either directly or after
processing.
Sample Preservation
I. For sample handling and preservation, see part 4.1 of the Atomic Absorption Methods
section of this manual.
Sample Preparation
1. For the analysis of total sodium in domestic and industrial effluents, the procedures for
the determination of total metals as given in parts 4.1.3 and 4.1.4 of the Atomic
Absorption Methods section of this manual have been found to be satisfactory.
2. For ambient waters, a representative aliquot of a well-mixed sample may be used directly
for analysis. If suspended solids are present in sufficient amounts to clog the nebulizer,
the sample may be allowed to settle and the supernatant liquid analyzed directly.
Instrumental Parameters (General)
1. Sodium hollow cathode Ijmp
2. Wavelength: 589.6 nm
3. Fuel: Acetylene
4. Oxidant Air
5 Ts'pe offl.nne CHuImn):
Approved for NI'DES
Issued 1971
Editorial revision 1974
271 i-i
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Section 4.0
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Analysis I'roccdiirc
I For the analysis procedure jnd the calculation, see "Direct Aspiration part 9 1 of the
Atomic Absorption Methods section of this manual
Notes
1. The 330.2 nm resonance line of sodium, which has a relative sensitivity of 185, provides a
convenient way to avoid the need to dilute more concentrated solutions of sodium.
2. Low-temperature flames increase sensitivity by reducing the extent of ionization of this
easily ionized metal. Ionization may also be controlled by adding potassium (1000 mg/l)
to both standards and samples.
3. Data to be entered into STORET must be reported as mg/l.
4. The flame photometric method may also be used (Standard Methods, 14th Edition, p.
250).
Precision and Accuracy
I. In a single laboratory (EMSL), using distilled water samples spiked at levels of 8.2 and 52
mgNa/l, the standard deviations were sO.l and t0.8, respectively. Recoveries at these
levels were 102% and 100%.
273 1-2
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Section 4.0
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Oate: 11/18/83
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Honomeric Aluminum Analysis
Monomerfc aluminum is extracted in the field and is obtained as the 8-
hydro^yquinollne In MIBK. The MIBK solution is analyzed for aluminum by
graphite furnace atomic absorption (GFAA), following the GFAA instrument
manufacturer's instructions for analyzing organic solutions. Background
correction must be used. Standards are prepared as follows:
a. Prepare dilute working standards in 10~5 M HC1 over the range
0.01-1 mg/L A1 using a 1,000 mg/L stock solution.
b. Pi pet 25.00-mL of a dilute standard into a clean 50-mL separatory
funnel.
c. Add 5.00-mL of 8-hydroxyquinoline sodium acetate reagent
(prepared daily by mixing, in order, 10-mL of 1.0 M sodium
acetate, 50-mL deionized water, and 10-mL 8-hydroxyquinoline
solution. The 8-hydroxyquinoline solution is prepared by
dissolving 5-g of ultrapure 8-hydroxyquinoline in 12.5-mL
glacial acetic acid, then dilute to 500-mL).
d.
Mix the solution thoroughly.
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Section 4.0
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Rapidly adjust the pH to 8.3 width lm NH4OH {determine the
pH by placing a drop of solution on a narrow range pH range),
add 2.0-mL of NH4+/NH3 buffer (prepared by adjusting the pH 2 of
21-ml of 4.7 M NH4OH to 8.3 with 2.5 M HC1), and 6.00-mL of
MIBK.
Extract the A1 by thorough mixing of the two phases (agitation
and Inversion for 2-3 minute).
Allow the phases to separate and isolate the MIBK layer.
The standards in MIBK are used to calibrate the GFAA instrument.
Reagent blanks and QC standards are prepared in the same manner.
NOTE: By using the same volumes as for samples, concentration
factors are taken into account.
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Sectior- 4.0
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ALUMINUM
Method 202.2 (Atomic Absorption, furnace technique)
STORET NO. Total 01105
Dissolved 01106
Suspended 01107
Optimum Concentration Range: 20-200 ug/l
Detection Limit: 3 ug/l
Preparation of Standard Solution
1. Stock solution: Prepare as described under "direct aspiration method".
2. Prepare dilutions of the stock solution to be used as calibration standards at the time of
analysis. These solutions are also to be used for "standard additions".
3. The calibration standard should be diluted to contain 0.5% (v/v) HNOj.
Sample Preservation
1. For sample handling and preservation, see part 4.1 of the Atomic Absorption Methods
section of this manual.
Sample Preparation
1. Prepare as described under "diroct aspiration method". Sample solutions for analysis
should contain 0.5% (v/v) HNO,.
Instrument Parameters (General)
1. Drying Time and Temp: 30seo-125*G
2. Ashing Time and Temp: 30sec-1300*G
3. Atomizing Time and Temp: 10sco-2700*G.
4. Purge Gas Atmmosphere: Argon
5. Wavelength: 309.3 nm
6. Other operating parameters should be set as specified by the particular instrument
manufacturer.
Analysis Procedure
I. For the analysis procedure and the caculation, see "Furnace Procedure" part 9.3 of the
Atomic Absorption Methods section of this manual
Approved for NPDES
Issued 1978
202 2-1
-------
Section A .0
Rev is 10-0 0
Date: 11/18/83
Page 89 of 96
-------
Notes
I ["he above concentration values and instrument conditions arc for a Pcrkin-Elmcr HG A-
2100, based on the use of a 20 u! injection, continuous flow purge gas and non-pyrolyttc
graphite.
2. Background correction may be required if the sample contains high dissolved solids.
3. It has been reported that chloride ion and that nitrogen used as a purge gas suppress the
aluminum signal. Therefore the use of halide acids and nitrogen as a purge gas should be
avoided.
4. For every sample matrix analyzed, verification is necessary to determine that method of
standard addition is not required (see part 5.2.1 of the Atomic Absorption Methods
section of this manual).
5. If method of standard addition is required, follow the procedure given earlier in part 8.S ¦
of the Atomic Absorption Methods section of this manual.
6. Data to be entered into STORET must be reported as ug/1.
Precision and Accuracy
I. Precision and accuracy data are not available at this time.
202 2-2
-------
FLUORIDE
Method 340.2 (Potentiometric, Ion Selective Electrode)
STORET NO: Total 00951
Dissolved 00950
1. Scope and Application
1.1 This method is applicable to the measurement of fluoride in drinking, surface and saline
waters, domestic and industrial wastes.
1.2 Concentration of fluoride from 0.1 up to 1000 mg/liter may be measured.
1.3 For Total or Total Dissolved Fluoride, the Bellack distillation is required for NPDES
monitoring but is not required for SDWA monitoring.
2. Summary of Method
2.1 The fluoride is determined potentiometrically using a fluoride electrode in conjunction
with a standard single junction sleeve-type reference electrode and a pH meter having an
expanded millivolt scale or a selective ion meter having a direct concentration scale for
fluoride.
2.2 The fluoride electrode consists of a lanthanum fluoride crystal across which a potential is
developed by fluoride ions. The cell may be represented by Ag/Ag CI, Cl'(0.3),
F(0.001) LaF/testsolution/SCE/.
3. Interferences
3.1 Extremes of pH interfere; sample pH should be between 5 and 9. Polyvalent cations of
Si**, Fe*' and AT' interfere by forming complexes with fluoride. The degree of
interference depends upon the concentration of the complexing cations, the
concentration of fluoride and the pH of the sample. The addition of a pH S.O buffer
(described below) containing a strong chelating agent preferentially complexes
aluminum (the most common interference), silicon and iron and eliminates the pH
problem.
4. Sampling Handling and Preservation
4.1 No special requirements.
5. Apparatus
5.1 Electrometer (pH meter), with expanded mv scale, or a selective ion meter such as the
Orion 400 Series.
5.2 Fluoride Ion Activity Electrode, such as Orion No. 94-09(,).
5.3 Reference electrode, single junction, sleeve-type, such as Orion No. 90-01, Beckman No.
40454, or Corning No. 476010.
5.4 Magnetic Mixer, Teflon-coated stirring bar.
Approved for NPDES and SDWA
Issued 1971
Editorial revision 1974
340 2-1
-------
So1.11ort 4.0
Rev 1 5 lO'V 0
Date: 11/18/83
Page 90 of 96
-------
I HON
Method 236.2 (Atomic Absorption, furnace technique)
STORET NO. Total 01045
Dissolved 01046
Suspended 01044
Optimum Concentration Range: 5-100 ug/i
Detection Limit: 1 ug/1
Preparation of Standard Solution
1. Stock Solution: Prepare as described under "direct aspiration method".
2. Prepare dilutions of the stock solution to be used as calibration standards at the time of
analysis. These solutions are also to be used for "standard additions".
3. The calibration standard should be diluted to contain 0.5% (v/v) HNOj.
Sample Preservation
1. For sample handling and preservation, see part 4.1 of the Atomic Absorption Methods
section of this manual.
Sample Preparation
1. Prepare as described under "direct aspiration method". Sample solutions for analysis
should contain 0.5% (v/v) HNOj.
Instrument Parameters (General)
1. Drying Time and Temp: 30 sec-l25*G.
2. Ashing Time and Temp: 30 soo-I000*C
3. Atomizing Time and Temp: 10 seo-2700"G
4. Purge Gas Atmosphere: Argon
5. Wavelength: 248.3 nm
6. Other operating parameters should be set as specified by the particular instrument
manufacturer.
Analysis Procedure
I. For the analysis procedure and the calculation, see "Furnace Procedure" part 9.3 of the
Atomic Absorption Methods section of this manual.
Notes
I The above concentration values am) instrument conditions arc for a Pcrkiit-Eliner HGA-
Z100, Ki^cil on tlie use ol a 20 ill injection continuous flow purge gas ami non-pyrolytic
Approved for NPDES
Issued 1978
236 2-1
-------
Section A .0
Revisicn 0
Date: 11/18/83
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-------
graphite Smaller sixe Uinucc devices or Uiom: employing faster rates of atomi7jtion can
be operated ustng lower atonuzalion temperatures for shorter time periods than the
above recommended settings
2. The use of background correction is recommended
3. Nitrogen may also be used as the purge gas.
4. For every sample matrix analyzed, verification is necessary to determine that method of
standard addition is not required (see part 5.2.1 of the Atomic Absorption Methods
section of this manual).
5. If method of standard addition is required, follow the procedure given earlier in part 8.5
of the Atomic Absorption Methods section of this manual.
6. Data to be entered into STORET must be reported as ug/1.
Precision and Accuracy
1. Precision and accuracy data are not available at this time.
236 2-2
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SILICA, DISSOLVED
Method 370.1 (Colorimetric)
STORET NO. Dissolved 00955
1. Scope and Application
1.1 This method is applicable to drinking, surface and saline waters, domestic and industrial
wastes.
1.2 The working range of the method is approximately 2 to 25 mg silica/1. The upper range
can be extended by taking suitable aliquots; the lower range can be extended by the
addition of amino-naphthol-sulfonic acid solution, as described in (6.8).
2. Summary of Method
2.1 A well-mixed sample is filtered through a 0.4S u membrane filter. The filtrate, upon the
addition of molybdate ion in acidic solution, forms a greenish-yellow color complex
proportional to the dissolved silica in the sample. The color complex is then measured
spectrophotometrically.
2.2 In the low concentration modification the yellow {410 nm) molybdosilicic acid color is
reduced by l-amino-2-naphthol-4-sulfonic acid to a more intense heteropoly blue (8 IS
nmor650 nm).
3. Interferences
3.1 Excessive color and/or turbidity interfere. Correct by running blanks prepared without
addition of the ammonium molybdate solution. See (6.7).
3.2 Tannin interference may be eliminated and phosphate interferences may be decreased
with oxalic acid.
3.3 Large amounts of iron and sulfide interfere.
3.4 Contact with glass should be minimized, silica free reagents should be used as much as
possible. A blank should be run.
4. Apparatus
4.1 Platinum dishes, 100 ml.
4.2 Colorimetric equipment-one of the following:
4.2.1 Spectrophotometer for use at 410 nm. 650 nm and/or 815 nm with a 1 cm or longer
cell
4.2.2 Filter photometer with a violet filter having maximum transmittance as near 410
nm as possible and a 1 cm or longer cell.
4.2.3 Nessler tubes, matched, 50 ml, tall form.
5. Reagents
5.1 Use chemicals low in silica and store in plastic containers
5 2 Sodium bicnrhonrtlc, NaHCO,, powder
5 3 .Sulfuric .u nl, 11,SO,. I N
Approved for NPD1£S
Issued 1971
Editorial revision 1978
370 l-l
-------
Section 0.0
Revision 0
Date: 11/18/83
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-------
54 I lytirocliloi il acid, JICI, ! I I
5 5 Ammonium molybdate reagent Place 10 g (NH,)6Mo,Oj,*4HjO m distilled water in a
100 ml volumetric. Dissolve by stirring and gently warming Dilute to the mark. Filter if
necessary. Adjust to pH 7 to 8 with silica free NH.OH or NaOH Store in plastic bottle.
5.6 Oxalic acid solution: Dissolve 10 g HjCi04*2Hi0 in distilled water in a 100 ml
volumetric flask, dilute to the mark. Store in plastic
5.7 Stock silica solution: Dissolve 4.73 g sodium mctasilicate nonahydrate, Na^iOj^HjO,
in recently boiled and cooled distilled water. Dilute to approximately 900 ml. Analyze
100.0 ml portions by gravimetry (ref. I, p. 484). Adjust concentration to 1.000 mg/1
SiO,. Store in tightly stoppered plastic bottle.
5.8 Standard silica solution: Dilute 10.0 ml stock solution to I liter with recently boiled and
cooled distilled water. This is 10 mg/1 Si02 (1.00 ml = 10.0 ug SiO^. Store In a tightly
stoppered plastic bottle.
5.9 Permanentcolorsolutions
5.9.1 Potassium chromate solution: Dissolve 630 mg K2Cr04 in distilled water in a 1
liter volumetric flask and dilute to the mark.
5.9.2 Borax solution: Dissolve 10 g sodium borate decahydrate, (Na^OylOHjO) in
distilled water in a 1 liter volumetric flask and dilute to the mark.
5.10 Reducing agent: Dissolve 500 mg of l-amino-2-naphthol-4-sulfonic acid and 1 g NaaSOj
in 50 ml distilled water with gentle wanning if necessary. Dissolve 30 g NaHSOj in 150
ml distilled water. Mix these two solutions. Filter into a plastic bottle. Refrigerate and
avoid exposure to light Discard when it darkens. If there is incomplete solubility or
immediate darkening of the aminonaphthosulfonic acid solution do not use.
6. Procedure
6.1 Filter sample through a 0.45 u membrane filter.
6.2 Digestion: If molybdate unreactive silica is present and its inclusion in the analysis is
desired, include this step, otherwise proceed to 6.3.
6.2.1 Place 50 ml, or a smaller portion diluted to 50 ml, of filtered (6.1) sample in a 100
ml platinum dish.
6.2.2 Add 200 mg silica-free NaHCO, (5.2) and digest on a steam bath for 1 hour. Cool.
6.2.3 Add slowly and with stirring 2.4 ml H3S04 (5.3).
6.2.4 Immediately transfer to a 50 ml Nessler tube, dilute to the mark with distilled
water and proceed to 6.3 without delay
6 3 Colordevelopment
6.3.1 Place 50 ml sample in a Nessler tube
6.3.2 Add rapidly 1.0 ml of 1 + 1 HCI (5 4) and 2.0 ml ammonium molybdate reagent
(5.5).
6.3.3 Mix by inverting at least 6 times.
6.3.4 Let stand 5 to 10 minutes
6 3 5 Add 15 ml oxalic ncid solution (S 6) .mil mix thoi out;111 v
fi 3 6 He.id color (spccirophoiomeu n. ilk 'it visu.ilk) .tfiei 2 minutes l>m before 15
mimiles from the addition of oxalic ai.ul
370 1-2
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6.4 Preparation of Standards
6 4.1 If digestion (6 2) was used add 200 mg NaHCO, (5 2) and 2 4 ml HjSO, (5 3) to
standards to compensate for silica introduced by these reagents and for effect of the
salt on the color intensity
6 5 Photometric measurement
6.5.1 Prepare a calibration curve using approximately six standards to span the range
shown below with the selected light path.
Selection of Light Path Length for Various
Silica Concentrations
Light Path
cm
1
2
5
10
Silica in 54.5 ml
final volume (ug)
200-1300
100-700
40-250
20-130
6.6
6.5.2 Carry out the steps in 6.3 using distilled water as the reference. Read a blank.
6.5.3 Plot photometric reading versus ug of silica in the final solution of 54.S ml. Run a
reagent blank and at least one standard with each group of samples.
Visual Comparison
6.6.1 Prepare a set of permanent artificial color standards according to the table. Use
well stoppered, properly labelled 50 ml Nessler tubes.
Potassium
Silica
chroma te
Borax
Distilled
value
solution
solution
water
mg
(5.9.1) ml
(5.9.2) ml
ml
0.00
0.0
25
30
0.10
1.0
25
29
0.20
2.0
25
28
040
40
25
26
0 50
50
25
25
0 75
75
25
22
1 00
too
25
20
6 7
6.6.2 Verify permanent standards by comparison to color developed by standard silica
solutions.
6 6 3 These permanent artificial color standards arc only for color comparison
procedure, not for photometric procedure
Corictiion for color or tuihiditv
6 7 I A spect.il bl.ink is run using a portion of lite sample .ind c.irrymg out the procedure
in 6 I, 6.2 if used, and 6 3 except for the addition of ammonium molybdntc (0 3 21
370 I-3
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6 7 2 Zero llie photometer with iliis blank before reading (he samples
Procedure for low concern ration ( < 1000 ug/1)
6 8.1 Perform steps 6 1 and 6.2 if needed
6 8.2 Place 50 ml sample in a Nessler tube
6.8.3 In rapid succession add 1.0 ml of I + I HCI (5 4)
6.8.4 Add 2.0 ml ammonium molybdate reagent (5.5).
6.8.5 Mix by inverting at least six times.
6.8.6 Let stand 5 to 10 minutes.
6.8.7 Add 1.5 ml oxalic acid solution (5.6).
6.8.8 Mix thoroughly.
6.8.9 At least 2, but not more than 15 minutes after oxalic acid addition, add 2.0 ml
reducing agent (5.10).
6.8.10 Mix thoroughly.
6.8.11 Wait 5 minutes, read photometrically or visually.
6.8.12 If digestion (6.2) was used see (6.4).
6.8.13 Photometric measurement
6.8.13.1 Prepare a calibration curve using approximately 6 standards and a
reagent blank to span the range shown below with the selected light
path.
Selection of Light Path Length for
Various Silica Concentrations
Light Path i>ilica in 56.5 ml Final volume, ug
650 nm 815 nm
1 40-300 20-100
2 20-150 10-50
5 7-50 4-20
10 4-30 2-10
6.8.13.2 Read versus distilled water.
6.8.13.3 Plot photometric reading at 650 nm or at 815 nm versus ug of silica in
56.5 ml.
6.8.13.4 For turbidity correction use 6.1, 6.2 if used and 6.8.2-6.8.11 omitting
6.8.4 and 6.8.9.
6.8.13.5 Run a reagent blank and at least one standard (to check calibration
curve drift) with each group of samples.
6.8.14 Visual comparison
6.8.14.1 Prepare not less than 12 standards covering the range of 0 to 120 ug
SiOj by placing the calculated volumes of standard silica (5.8) in 50 ml
Nessler tubes, diluting to the mark and develop the color as in
6 8 2-6 B 11
370 ! -4
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Calculations
7.1 Read ugStO, from calibration curve or by visual companion
7.2 mg/l SiO, =
Ug'S.O,
ml sample
7.3 Report whether NaHCOj digestion (6 2) was used
Precision and Accuracy
8.1 A synthetic unknown sample containing 5.0 mg/l Si02, 10 mg/l chloride, 0.200 mg/l
ammonia N, 1.0 mg/l nitrate N, 1.5 mg/l organic N, and 10.0 mg/l phosphate in
distilled water was analyzed in 19 laboratories by the molybdosilicate method, with a
relative standard deviation of 14.3% and a relative error of 7.8%.
8.2 Another synthetic unknown sample containing 15.0 mg/l Si02, 200 mg/l chloride,
0.800 mg/l ammonia N, 1.0 mg/l nitrate N, 0.800 mg/l organic N, and 5.0 mg/l
phosphate in distilled water was analyzed in 19 laboratories by the molybdosilicate
method, with a relative standard deviation of 8.4% and a relative error of 4.2%.
8.3 A third synthetic unknown sample containing 30.0 mg/l Si02,400 mg/I chloride, 1.50
mg/l ammonia N, 1.0 mg/l nitrate N, 0.200 mg/l organic N, and 0.500 mg/l
phosphate in distilled water was analyzed in 20 laboratories by the molybdosilicate
method, with a relative standard deviation of 7.7% and a relative error of 9.8%. All
results were obtained after sample digestion with NaHCO,.
8.4 Photometric evaluations by the amino-naphthol-sulfonic acid procedure have an
estimated precision of ±0.10 mg/l in the range from 0 to 2 mg/l (ASTM).
8.5 Photometric evaluations of the silico-molybdate color in the range from 2 to 50 mg/l
have an estimated precision of approximately 4% of the quantity of silica measured
(ASTM).
Bibliography
Annual Book of ASTM Standards, Part 31, "Water", Standard D859-£8, p 401 (1976).
Standard Methods for the Examination of Water and Wastewater, 14th Edition, p 487,
Method 426B,(1975).
370 1-5
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Section S.O
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5.0 DATA REPORTING
Sample results for the parameters listed in Table 5.1 are to be reported
on the data form given in Figure 5.1. Also, copies of raw data (including
calibration data) must be included with the form. Forms for other parameters
are included with the appropriate method.
TABLE 5.1 PARAMETERS TO BE REPORTED ON THE FORM IN FIGURE 5.1
Total phosphorus
Dissolved organic carbon
Ammonium
Nitrate
Nitrite
Fluoride
Chloride
Sulfate
Ca1c i um
Magnesium
Manganese
Potassium
Sodium
(continued)
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Section 5.0
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TABLE 5.1 Continued)
Aluminum
Iron
Si 1ica
Monomeric aluminum
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Data Form Analyte (a)
Lab ID: Operator
Analyte
EPA Sample ID
Lab Sample ID
(mq/L)
Recovery %
1.
QC standard (b)
2.
—
3.
Analyst spike of sample
"2" (c)
4.
Reagent blank (d)
—
5.
—
6.
—
7.
—
8.
—
9.
—
10.
—
11. —
QC standard (b)
12. --
Calibration blank
—
13.
—
14.
—
15.
—
16.
—
17.
—
18.
--
19.
—
20.
(Duplicate)
(a) The QC samples indicated must be analyzed for each set of 20 or less
samples QC standard (20 includes the QC samples).
(b) QC standard concentration = mg/L
(c) Concentration of analyst spike = _mg/L
(d) Disregard if a reagent blank is not necessary, i.e., there is no sample
preparation involved in the analysis.
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Section 5.0
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5.1 REFERENCES
1- Topol, L. E., and S. Ozdemir. Quality Assurance Handbook for
Air Pollution Measurement Systems: Part II. Operation and Maintenance
Manual. EPA-600/4-82-042b.
2. EPA Methods for Chemical Analysis of Water and Wastes.
EPA-600/4-79-020.
3. Galloway, J. N., B. 0. Cosby, Jr., and G. E. Likens. 1979.
Limnol. Oceanogr., 24(6), pp 1161-1165.
4. McQuaker, N. R., P. D. Kluckner, and D. K. Sandberg. 1983.
Environ. Sci. Techno!., 17(7), pp 431-435.
5. Gran, G. 1952. Analyst, 77, 661-671.
6. 1983 Annual Book of ASTM Standards. Section 11, Water and
Environmental Technology. Volume 11.01, Water (1). pp. 696-703.
7. Driscoll, C. T., J. P. Baker, J. J. 8osogni, and C. L. Schofield.
(In Press). Acid Precipitation Geological Aspects, Ann Arbor
Science, Ann Arbor, Michiyan.
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APPENDIX A
METAL ANALYSIS BY ATOMIC ABSORPTION AND INDUCTIVELY COUPLED
PLASMA EMISSION SPECTROSCOPY (EPA METHOD 200.0 AND 200.7)
-------
METALS
(Atomic Absorption Methods)
1 Scope and Application
1.1 Metals in solution may be readily determined by atomic absorption spectroscopy. The
method is simple, rapid, and applicable to a large number of metals in drinking, surface,
and saline waters, and domestic and industrial wastes. While drinking waters free of
particulate matter may be analyzed directly, domestic and industrial wastes require
processing to solubilize suspended materia!. Sludges, sediments and other solid type
samples may also be analyzed after proper pretreatment.
1.2 Detection limits, sensitivity and optimum ranges of the metals will vary with the various
makes and models of satisfactory atomic absorption spectrophotometers. The data
shown in Table 1, however, provide some indication of the actual concentration ranges
measurable by direct aspiration and using furnace techniques. In the majority of
instances the concentration range shown in the tabic by direct aspiration may be
extended much lower with scale expansion and conversely extended upwards by using a
less sensitive wavelength or by rotating the burner head. Detection limits by direct
aspiration may also be extended through concentration of the sample and/or through
solvent extraction techniques. Lower concentrations may also be determined using the
furnace techniques. The concentration ranges given in Table 1 are somewhat dependent
on equipment such as the type of spectrophotometer and furnace accessory, the energy
source and the degree of electrical expansion of the output signal. When using furnace
techniques, however, the analyst should be cautioned as to possible chemical reactions
occurring at elevated temperatures which may result in either suppression or
enhancement of the analysis element To insure valid data with furnace techniques, the
analyst must examine each matrix for interference effects (see 5.2.1) and if detected, treat
accordingly using either successive dilution, matrix modification or method of standard
additions (see S.5).
1.3 Where direct aspiration atomic absorption techniques do not provide adequate
sensitivity, in addition to the furnace procedure, reference is made to specialized
procedures such as the gaseous hydride method for arsenic and selenium, the cold vapor
technique for mercury, and the chelation-ex traction procedure for selected metals.
Reference to approved colorimetric methods is also made.
1.4 Atomic absorption procedures are provided as the methods of choice; however, other
instrumental methods have also been shown to be capable of producing precise and
accurate analytical data. These instrumental techniques include emission spectroscopy,
X-ray fluorescence, spark source mass spectroscopy, and anodic stripping to name but a
few The analyst should be cautioned that these methods arc highly specialized
techniques requiring a high degree of skill (o interpret result and obum valid data
Approved for NPDES and SDWA
Issued 1969
Editorial revision 1974 and 1978
MF.TA1.S-1
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These above mentioned techniques .ire presently considered as alternate test procedures
and approval must be obtained prior to their use
2 Summary of Method
2.1 In direct aspiration atomic absorption spectroscopy a sample is aspirated and atomiied
in a flame. A light beam from a hollow cathode lamp whose cathode is made of the
element to be determined is directed through the flame into a monochromator, and onto
a detector that measures the amount of light absorbed. Absorption depends upon the
presence of free unexcited ground state atoms in the flame. Since the wavelength of the
light beam is characteristic of only the metal being determined, the light energy absorbed
by the flame is a measure of the concentration of that metal in the sample. This principle
is the basis of atomic absorption spectroscopy.
2.2 Although methods have been reported for the analysis of solids by atomic absorption
spectroscopy (Spectrochim Acta, 24B S3, 1969) the technique generally is limited to
metals in solution or solubilized through some form of sample processing.
2.2.1 Preliminary treatment of wastewater and/or industrial effluents is usually
necessary because of the complexity and variability of the sample matrix.
Suspended material must be subjected to a solubilization process before analysis.
This process may vary because of the metals to be determined and the nature of the
sample being analyzed. When the breakdown of organic material is necessitated,
the process should include a wet digestion with nitric acid.
2.2.2 In those instances where complete characterization of a sample is desired, the
suspended material must be analyzed separately. This may be accomplished by
filtration and acid digestion of the suspended material. Metallic constituents in this
acid digest are subsequently determined and the sum of the dissolved plus
suspended concentrations will then provide the total concentrations present. The
sample should be filtered as soon as possible after collection and the filtrate
acidified immediately.
2.2.3 The total sample may also be treated with acid without prior filtration to measure
what may be termed "total recoverable" concentrations.
2.3 When using the furnace technique in conjunction with an atomic absorption
spectrophotometer, a representative aliquot of a sample is placed in the graphite tube in
the furnace, evaporated to dryness, charred, and atomized. As a greater percentage of
available anaiyte atoms are vaporized and dissociated Tor absorption in the tube than the
flame, the use of small sample volumes or detection of low concentrations of elements is
possible. The principle is essentially the same as with direct aspiration atomic absorption
except a furnace, rather than a flame, is used to atomize the sample. Radiation from a
given excited element is passed through the vapor containing ground state atoms of that
element. The intensity of the transmitted radiation decreases in proportion to the amount
of the ground state element in the vapor
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TAilLE 1
Atomic Absorption Concentration Ranges'"
Direct Aspiration Furnace Procedure'*»"
Optimum
Optimum
Detection
Con central ion
Detection
Concentration
Limit
Sensitivity
Range
Limit
Range
Metal
mg/l
mg/l
mg/l
ug/l
ug/l
Aluminum
01
t
5
_
50
J
20
-
200
Antimony
0.2
0.5
1
-
40
J
20
-
300
Anemc™
0X02
-
0002
-
ao2
1
3
-
100
Barium(p)
0.1
0.4
1
-
20
2
10
-
200
Beryllium
0.005
0.025
0.05
-
2
0.2
I
-
30
Cadmium
0.00}
ao2s
0.05
-
2
0.1
as
-
10
Calcium
0.01
0.08
0.2
-
7
-
-
-
Chromium
0.05
0.25
0.5
-
10
1
s
-
100
Cobalt
0.05
0.2
as
-
5
1
s
-
100
Copper
0.02
0.1
0.2
-
S
1
3
-
100
Cold
at
005
0.5
-
20
1
3
-
100
Iridium(p)
j
t
20
-
500
30
too
-
1500
Iron
0.03
0.12
aj
-
5
1
s
-
too
Lead
0.1
0.5
1
-
20
1
3
-
100
Magnesium
0.001
0.007
ao2
-
as
-
-
-
Manganese
0.01
ao5
at
-
i
0.2
1
-
30
Mercury"
0.0002
-
0.0002 -
aoi
-
-
-
Molybdenum(p)
0.1
0.4
i
-
40
I
3
-
£0
NickeKp)
aw
ais
0.3
-
s
1
3
-
50
Ounium
ai
i
2
-
too
20
SO
-
500
Palladiuin(p)
ai
0JU
as
-
IS
5
20
-
400
Plitinum{p)
0.2
2
5
-
75
20
100
-
2000
Potassium
aoi
0.04
at
-
2
-
-
Rhenium(p)
5
13
so
-
1000
200
500
-
3000
Rhodium(p)
0.03
0J
t
-
10
3
20
-
400
Ruthenium
0.2
as
i
-
so
20
100
-
2000
Selenium*0
0.002
-
0.002
-
0.02
2
3
-
100
Silver
0.01
ao6
ai
-
4
0.2
1
-
25
Sodium
0.002
0.015
0.0)
-
1
-
-
-
Thallium
0.1
0.5
i
-
20
1
5
-
too
Tin
08
4
10
-
300
5
20
-
300
Titanium (p)
04
2
5
-
100
10
50
-
500
Vanadium (p)
02
OS
2
-
100
4
10
-
200
Zinc
0005
002
005
-
1
0 05
02
-
4
(1) The concentrations shown are not contrived values and should be obtainable with any satisfactory atomic absorption
spectrophotometer
(2) Gaseous hydndc method
{3) Cold vapor technique
(4) Tor furnace sensitivity values consult instrument operating uunual
(5) ~\ he listed furnace values are those expected when u&tng a 20 ul injection and normal gas flow etcepl in (he ca*e of arsenic and
selenium where gas interrupt is used The symbol (p) indicates the utf of pyrolyoc graphite wiih the furnace procedure
MR! ALSO
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1 he metal atoms to be measured arc placed in the beam of radiation by increasing the temperature of
the furnace thereby causing the injected specimen to be volatilized. A monochromator isolates the
characteristic radiation from the hollow cathode lamp and a photosensitive device measures the
attenuated transmitted radiation.
3 Definition ofTcrms
3.1 Optimum Concentration Range: A range, defined by limits expressed in concentration,
below which scale expansion must be used and above which curve correction should be
considered. This range will vary with the sensitivity of the instrument and the ope'rattng
condition employed.
3.2 Sensitivity; The concentration in milligrams of metal per liter that produces an
absorption of 1%.
3.3 Detection Limit: Detection limits can be expressed as either an instrumental or method
parameter. The limiting factor of the former using acid water standards would be the
signal to noise ratio and degree of scale expansion used; while the latter would be more
affected by the sample matrix and preparation procedure used. The Scientific Apparatus
Makers Association (SAMA) has approved the following definition for detection limit:
that concentration of an element which would yield an absocbance equal to twice the
standard deviation of a series of measurements of a solution, the concentraton of which is
distinctly detectable above, but close to blank absorbance measurement. The detection
limit values listed in Table I and on the individual analysis sheets are to be considered
minimum working limits achievable with the procedures given in this manual. These
values may differ from the optimum detection limit reported by the various instrument
manufacturers.
3.4 Dissolved Metals: Those constituents (metals) which will pass through a 0.4S u
membrane filter.
3.5 Suspended Metals: Those constituents (metals) which are retained by a 0.45 u membrane
filter.
3.6 Total Metals: The concentration of metals determined on an unfiltered sample following
vigorous digestion (Section 4.1.3), or the sum of the concentrations of metals in both the
dissolved and suspended fractions.
3.7 Total Recoverable Metals: The concentration of metals in an unfiltered sample following
treatment with hot dilute mineral acid (Section 4.1.4).
4. Sample Handling and Preservation
4.1 For the determination of trace metals, contamination and loss are of prime concern. Dust
in the laboratory environment, impurities in reagents and impurities on laboratory
apparatus which the sample contacts are all sources of potential contamination. For
liquid samples, containers can introduce either positive or negative errors in the
measurement of trace metals by (a) contributing contaminants through leaching or
surface desorption and (b) by depleting concentrations through adsorption Thus the
collection and treatment of the sample pnor to analysis requires particular attention The
sample Isotile whether Ijorosihcatc f;lass, polyethylene j>oly|>ropylcncor Teflon should
tx.' thoroughly washed wiih detcrgem and cap water, rinsed with I.I nunc .icid, tap
MF.TALS-4
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water, 1 1 hydrochloric acid, tap water and finally doom zed distilled water in (hat
order.
NOTE 1: Chromic acid may be useful to remove organic deposits from glassware,
however, the analyst should be cautioned that the glassware must be thoroughly rinsed
with water to remove the last traces of chromium. This is especially important if
chromium is to be included in the analytical scheme. A commercial product—
NOCHROMIX—available from Godax Laboratories, 6 Varick St. New York, N.Y.
10013, may be used in place of chromic acid. [Chromic acid should not be used with
plastic bottles.)
NOTE 2: If it can be documented through an active analytical quality control program
using spiked samples, reagent and sample blanks, that certain steps in the cleaning
procedure are not required for routine samples, those steps may be eliminated from the
procedure.
Before collection of the sample a decision must be made as to the type of data desired, i.e.,
dissolved, suspended, total or total recoverable. For container preference, maximum
holding time and sample preservation at time of collection see Table 1 in the front part of
this manual. Drinking water samples containing suspended and setteable material should
be prepared using the total recoverable metal procedure (section 4.1.4).
4.1.1 For the determination of dissolved constituents the sample must be filtered
through a 0.45 u membrane filter as soon as practical after collection. (Glass or
plastic filtering apparatus using plain, non-grid marked, membrane filters are
recommended to avoid possible contamination.) Use the first 50-100 ml to rinse
the filter flask. Discard this portion and collect the required volume of filtrate.
Acidify the filtrate with 1:1 redistilled HNOj to a pH of <2. Normally, 3 ml of
(1:1) acid per liter should be sufficient to preserve the sample (See Note 3). If
hcxavaknt chromium is to be included in the analytical scheme, a portion of the
filtrate should be transferred before acidification to a separate container and
analyzed as soon as possible using Method 218.4. Analyses performed on a sample
so treated shall be reported as "dissolved" concentrations.
NOTE 3: If a precipitate is formed upon acidification, the filtrate should be digested
using 4.1.3. Also, it has been suggested (International Biological Program, Symposium
on Analytical Methods, Amsterdam, Oct 1966) that additional acid, as much as 25 ml of
conc. HCl/liter, may be required to stabilize certain types of highly buffered samples if
they are to be stored for any length of time. Therefore, special precautions should be
observed for preservation and storage of unusual samples intended for metal analysis.
4.1.2 For the determination of suspended metals a representative volume of unprescrved
sample must be filtered through a 0.45 u membrane filter. When considerable
suspended material is present, as little as 100 ml of a well mixed sample is filtered.
Record the volume filtered and transfer the membrane filter containing the
insoluble materia) to a 250 ml Griffin beaker and add 3 m! conc redistilled HNO
Cover the beaker with a watch glass and heal gently The warm acid will soon
dissolve the membrane Increase the temperature of the hot plate and digest the
material. When the acid has nearly evaporated, cool the beaker and watch glass
and add another 3 ml of conc. redistilled HNO) Cover and continue heating until
MCTAI.S-5
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[lie digestion is complete, generally indicated by a light colored digesute
Evaporate to near dryness (DO NOT BAKE), add 5 ml distilled HCI (1-1) and
warm the beaker gently to dissolve any soluble material. (Jf the sample is to be
analyzed by the furnace procedure, 1 ml ofl: I distilled HNO, per 100 ml dilution
should be substituted for the distilled I I HCI.) Wash down the watch glass and
beaker walls with deionized distilled water and filter the sample to remove silicates
and other insoluble material that could clog the atomizer. Adjust the volume to
some predetermined value based on the expected concentrations of metals present.
This volume will vary depending on the metal to be determined. The sample is now
ready for analysis. Concentrations so determined shall be reported as "suspended"
(See Note 4.)
NOTE 4: Certain metals such as antimony arsenic, gold, iridium, mercury,
osmium, palladium, platinium, rhenium, rhodium, ruthenium, selenium, silver,
thallium, tin and titanium require modification of the digestion procedure and the
individual sheets for these metals should be consulted.
4.1.3 For the determination of total metals the sample is acidified with 1:1 redistilled
HNOj to a pH of less than 2 at the time of collection. The sample is not filtered
before processing. Choose a volume of sample appropriate for the expected level of
metals. If much suspended material is present, as little as 50-100 ml of well mixed
sample will most probably be sufficient (The sample volume required may also
vary proportionally with the number of metals to be determined.)
Transfer a representative aliquot of the well mixed sample to a Griffin beaker and
add 3 ml of conc. redistilled HNOj. Place the beaker on a hot plate and evaporate
to near dryness cautiously, making certain that the sample does not boil. (DO NOT
BAKE.) Cool the" beaker and add another 3 ml portion of conc. redistilled HNOj.
Cover the beaker with a watch glass and return to the hot plate. Increase the
temperature of the hot plate so that a gentle reflux action occurs. Continue heating,
adding additional acid as necessary, until the digestion is complete (generally
indicated when the digestate is light in color or does not change in appearance with
continued refluxing). Again, evaporate to near dryness and cool the beaker. Add a
small quantity of redistilled 1:1 HCI-(5 ml/100 ml of final solution) and warm the
beaker to dissolve any precipitate or residue resulting from evaporation. (If the
sample is to be analyzed by the furnace procedure, substitute distilled HNOj for 1:1
HCI so that the final dilution contains 0.5% (v/v) HNOj.) Wash down the beaker
walls and watch glass with distilled water and filter the sample to remove silicates
and other insoluble material that could clog the atomizer. Adjust the volume to
some predetermined value based on the expected metal concentrations. The sample
is now ready for analysis. Concentrations so determined shall be reported as
"total" (see Note 4)
4 M To determine total recoverable inetals, .icidify the entire sample at the time of
collection with conc redistilled HNO,. 5 ml/1 At the tunc of analysis :i 100 ml
aliquot of well mixed sample is iransferred to a beaker or flask Five nil of distilled
HCI (I I) is added and the sample heated on a steam bath or hot plate until lite
MIH ALS-6
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volume has been reduced to 15-20 ml making certain the samples do not boil (If
the sample is being prepared for furnace analysts, the same process should be
followed except HCI should be omitted ) After this treatment the sample is filtered
to remove silicates and other insoluble material that could clog the atomjzer and
the volume adjusted to 100 ml The sample is then ready for analysis.
Concentrations so determined shall be reported as "total". (See Notes 4, 5, and 6.)
NOTE 5: The analyst should be cautioned that this digestion procedure may not be
sufficiently vigorous to destroy certain metal complexes if a colorimctric procedure
is to be employed for the final determination. When this is suspect, the more
vigorous digestion given in 4.1.3 should be followed.
NOTE 6: For drinking water analyses by direct aspiration, the final volume may be
reduced to effect up to a 10X concentration of the sample, provided the total
dissolved solids in the original sample do not exceed 500 mg/1, the determination
is corrected for any non-specific absorbance and there is no loss by precipitation.
5. Interferences
5.1 Direct Aspiration
5.1.1 The most troublesome type of interference in atomic absorption
spectrophotometry is usually termed "chemical" and is caused by lack of
absorption of atoms bound in molecular combination in the flame. This
phenomenon can occur when the flame is not sufficiently hot to dissociate the
molecule, as in the case of phosphate interference with magnesium, or because the
dissociated atom is immediately oxidized to a compound that will not dissociate
Further at the temperature of the flame. The addition of lanthanum will overcome
the phosphate interference in the magnesium, calcium and barium determinations.
Similarly, silica interference in the determination of manganese can be eliminated
by the addition of calcium.
5.1.2 Chemical interferences may also be eliminated by separating the metal from the
interfering material. While complexing agents are primarily employed to increase
the sensitivity of the analysis, they may also be used to eliminate or reduce
interferences.
5.1.3 The presence of high dissolved solids in the sample may result in an interference
from non-atomic absorbance such as light scattering. If background correction is
not available, a non-absorbing wavelength should be checked. Preferably, high
solids type samples should be extracted (see 5.1.1 and 9.2).
5.1.4 Ionization interferences occur where the flame temperature is sufficiently high to
generate the removal of an electron from a neutral atom, giving a positive charged
ion. This type of interference can generally be controlled by the addition, to both
standard and sample solutions, of a large excess of an easily ionized element.
5 1.5 Although quite rare, spectral interference can occur when an absorbing
wavelength of an element present in the sample but not being determined falls
vm th m (he widt h of I lie abvn pi ion line of I lie element <>l uitei est 1 lie results of die
determination will then lie eironeously high, due to the contribution of the
interfering clement to the aiomic absorption signal Also, interference can occur
Mi:I ALS-7
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Appendix A
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when icsoiunt energy from another element in a multi-element lamp or a metal
impurity in the lamp cathode falls within the bandpass of the slit setting and that
metal ts present in the sample This type of interference may sometimes be reduced
by narrowing the slit width
5 2 Flamcless Atomization
5.2 I Although the problem of oxide formation is greatly reduced with furnace
procedures because atomization occurs in an inert atmosphere, the technique is
still subject to chemical and matrix interferences. The composition of the sample
matrix can have a major effect on the analysis. It is those effects which must be
determined and taken into consideration in the analysis of each different matrix
encountered. To help verify the absence of matrix or chemical interference use the
following procedure. Withdraw from the sample two equal aliquots. To one of the
aliquots add a known amount of analyte and dilute both aliquots to the same
predetermined volume. [The dilution volume should be based on the analysis of the
undiluted sample. Preferably, the dilution should be 1:4 while keeping in mind the
optimum concentration range of the analysis. Under no circumstances should the
dilution be less than 1:1]. The diluted aliquots should then be analyzed and the
unspiked results multiplied by the dilution factor should be compared to the
original determination. Agreement of the resutts (within ±10%) indicates the
absence of interference. Comparison of the actual signal from the spike to the
expected response from the analyte in an aqueous standard should help confirm the
finding from the dilution analysis. Those samples which indicate the presence of
interference, should be treated in one or more of the following ways.
a. The samples should be successively diluted and reanalyzed to
determine if the interference can be eliminated.
b. The matrix of the sample should be modified in the furnace. Examples
are the addition of ammonium nitrate to remove alkali chlorides,
ammonium phosphate to retain cadmium, and nickel nitrate for
arsenic and selenium analyses [ATOMIC ABSORPTION
NEWSLETTER Vol 14, No. 5, p 127, Sept-Oct 1975]. The mixing of
hydrogen with the inert purge gas has also been used to suppress
chemical interference. The hydrogen acts as a reducing agent and aids
in molecular dissociation.
c. Analyze the sample by method of standard additions while noting the
precautions and limitations of its use (See 8.5).
5.2.2 Gases generated in the furnace during atomization may have molecular absorption
bands encompassing the analytical wavelength. When this occurs, either the use of
background correction or choosing an alternate wavelength outside the absorption
band should eliminate this interference Non-specific broad band absorption
interference can also be compensated for with background correction
5 2 3 Interference from a smoke-producing sample matrix can sometimes be reduced by
extending the charring lime ji a higher temperature or utilizing an nslung cycle in
MTTALS-8
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the presence of air Care must be (aken, however, 10 prevent loss of the analysis
element
5 2 4 Samples containing large amounts of organic materials should be oxidized by
conventional acid digestion prior to being placed in the furnace In this way broad
band absorption will be minimized.
5.2.5 From anion interference studies in the graphite furnace it is generally accepted that
nitrate is the preferred anion. Therefore nitric acid is preferable for any digestion or
solubilization step. If another acid in addition to HNOj is required a minimum
amount should be used. This applies particularly to hydrochloric and to a lesser
extent to sulfuric and phosphoric acids.
5.2.6 Carbide formation resulting from the chemical environment of the furnace has
been observed with certain elements that form carbides at high temperatures.
Molybdenum may be cited as an example. When this takes place, the metal will be
released very slowly from the carbide as atomization continues. For molybdenum,
one may be required to atomize for 30 seconds or more before the signal returns to
baseline levels. This problem is greatly reduced and the sensitivity increased with
the use of pyrolytically-coated graphite.
5.2.7 Ionization interferences have to date not been reported with furnace techniques.
5.2.8 For comments on spectral interference see section 5.1.5.
5.2.9 Contamination of the sample can be a major source of error because of the extreme
sensitivities achieved with the furnace. The sample preparation work area should
be kept scrupulously clean. All glassware should be cleaned as directed in part 6.9
of the Atomic Absorption Methods section of this manual Pipet tips have been
known to be a source of contamination. If suspected, they should be acid soaked
with 1:5 HNOj and rinsed thoroughly with tap and deionized water. The use of a
better grade pipet tip can greatly reduce this problem. It is very important that
special attention be given to reagent blanks in both analysis and the correction of
analytical results. Lasdy, pyrolytic graphite because of the production process and
handling
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6 5 Strip chart recorder. A recorder is strongly recommended for furnace work so that there
will be a permanent record and any problems with the analysis such as drift, incomplete
atomization, losses during charring, changes in sensitivity, etc., can be easily recognized.
6 6 Pipets: Microliter with disposable tips. Sires can range from 5 to 100 microliters as
required. NOTE 7: Pipet tips which are white in color, do not contain CdS, and have
been found suitable for research work are available from Ulster Scientific, Inc. 53 Main
St. Highland, NY 12528(914)691-7500.
6.7 Pressure-reducing valves: The supplies of fuel and oxidant shall be maintained at
pressures somewhat higher than the controlled operating pressure of the instrument by
suitable valves.
6.8 Separatory flasks: 250 ml, or larger, for extraction with organic solvents.
6.9 Glassware: All glassware, linear polyethylene, polyproplyene or Teflon containers,
including sample bottles, should be washed with detergent, rinsed with tap water, 1:1
nitric acid, tap water, 1:1 hydrochloric acid, tap water and deionized distilled water in
that order. (See Notes 1 and 2 under (4.1) concerning the use of chromic acid and the
cleaning procedure.]
6.10 Borosilicate glass distillation apparatus.
7. Reagents
7.1 Deionized distilled water: Prepare by passing distilled water through a mixed bed of
cation and anion exchange resins. Use deionized distilled water for the preparation of all
reagents, calibration standards, and as dilution water.
7.2 Nitric acid"(conc.): If metal impurities are found to be present, distill reagent grade
nitric acid in a borosilicate glass distillation apparatus or use a spectrograde acid.
Caution: Distillation should be performed in hood with protective sash in place.
7.2.1 Nitric Acid (1:1): Prepare a 1:1 dilution with deionized, distilled water by
adding the conc. acid to an equal volume of water.
7.3 Hydrochloric acid (1:1): Prepare a 1:1 solution of reagent grade hydrochloric acid and
deionized distilled water. If metal impurities are found to be present distill this mixture
from a borosilicate glass distillation apparatus or use aspectrograde acid.
7.4 Stock standard metal-solutions: Prepare as directed in (SJ) and under the individual
metal procedures. Commercially available stock standard solutions may also be used.
7.5 Calibration standards: Prepare a series of standards of the metal by dilution of the
appropriate stock metal solution to cover the concentration range desired.
7.6 Fuel and oxidant: Commercial grade acetylene is generally acceptable. Air may be
supplied from a compressed air line, a laboratory compressor, or from a cylinder of
compressed air. Reagent grade nitrous oxide is also required for certain determinations.
Standard, commercially available argon and nitrogen are required for furnace work.
7.7 Special reagents for the extraction procedure.
7.7.1 Pyrrolidine dithiocarbamic acid (PDCA) "see footnote": Prepare by adding 18
ml of analytical reagent grade pyrrolidine io 500 ml of chloroform in a liter flask
The name pyrrolidine dithiocarbamic acid (I'DCA). although commonly referenced in the scientific
literature is ambiguous From the chemical reaction of pyrrolidine and carbon disulfide a more
proper name would be 1-pyrrolidine carboditluoic acid. I'CDA (CAS Registry No 25769-03-3)
MCTALS-IO
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(See Note 8} Cool and add 15 ml of carbon disulfide in small portions and with
swirling. Dilute to I liter with chloroform The solution can be used for several
months if stored in a brown bottle in a refrigerator
NOTE 8: An acceptable grade of pyrrolidine may be obtained from the Aldnch
Chemical Co., 940 West St. Paul Ave., Milwaukee, WI. 53233 (414,273-3850).
7.7.2 Ammonium hydroxide, 2N: Dilute 13 ml conc. NH
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3.
4.
5.
Fuel' Acetylene
Oxidant: Air
Type of flame: Oxidizing
Notes
1. The interference caused by aluminum at concentrations greater than 2 mg/1 is masked
by addition of lanthanum. Sodium, potassium and calcium cause no interference at
concentrations less than 400 mg/1.
2. The following line may also be used:
202.S nm Relative Sensitivity 25
3. To cover the range of magnesium values normally observed in surface waters (0.1-20
mg/1), it is suggested that either the 202.5 nm line be used or the burner head be rotated.
A 90 rotation of the burner head will produce approximately one-eighth the normal
sensitivity.
4. Data to be entered into STORET must be reported as mg/I.
5. The gravimetric method may also be used (Standard Methods, 14th Edition, p 221).
Precision and Accuracy
1. In a single laboratory (EMSL), using distilled water spiked at concentrations of 2.1 and
8.2 mg Mg/1 the standard deviations were *0.1 and ±0.2, respectively. Recoveries at
both of these levels were 100%.
24' 1-2
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8.4 For those instruments which do not read out directly in concentration, a calibration
curve is prepared to cover the appropriate concentration range. Usually, this means the
preparation of standards which produce an absorption of 0 to 80 percent. The correct
method is to convert the percent absorption readings to absorbance and plot that value
against concentration. The following relationship is used to convert absorption values to
absorbance:
absorbance = log (100/%T) = 2-log % T
where %T = 100-% absorption
As the curves are frequently nonlinear, especially at high absorption values, the number
of standards should be increased in that portion of the curve.
8.5 Method of Standard Additions: In this method, equal volumes of sample are added to a
deionized distilled water blank and to three standards containing different known
amounts of the test element The volume of the blank and the standards must be the
same. The absorbance of each solution is determined and then plotted on the vertical axis
of a graph, with the concentrations of the known standards plotted on the horizontal
axis. When the resulting line is extrapolated back to zero absorbance, the point of
interception of the abscissa is the concentration of the unknown. The abscissa on the left
of the ordinate is scaled the same as on the right side, but in the opposite direction from
the ordinate. An example of a plot so obtained is shown in Fig. 1.
Zei
Abso.
Concentration
Cone, of
Sample
Addn 0
No Addn
Addn I
Addn of 50%
of Expected
Amount
Addn 2 Addn 3
Addn of 100V. Addn of 150%
of Expected of E*paci«d
Amount Amount
FIGURE 1. STANDARD ADDITION PLOT
MI'l ALS-12
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The method of standaid additions can be very useful, however, for the results to be valid
the following limitations must be taken into consideration
a) the absorbance plot of sample and standards must be linear over the
concentration range of concern. For best results the slope of (he plot should
be nearly the same as the slope of the aqueous standard curve. If the slope is
significantly different (more than 20%) caution should be exercised.
b) the effect of the interference should not vary as the ratio of analyte
concentration to sample matrix changes and the standard addition should
respond in a similar manner as the analyte.
c) the determination must be free of spectral interference and corrected for non-
specific background interference.
9- General Procedure for Analysis by Atomic Absorption
9.1 Direct Aspiration: Differences between the various makes and models of satisfactory
atomic absorption spectrophotometers prevent the formulation of detailed instructions
applicable to every instrument The analyst should follow the manufacturer's operating
instructions for his particular instrument In general, after choosing the proper hollow
cathode lamp for the analysis, the lamp should be allowed to warm up for a minimum of
15 minutes unless operated in a double beam mode. During this period, align the
instrument, position the monochromator at the correct wavelength, select the proper
monochromator slit width, and adjust the hollow cathode current according to the
manufactuerer's recommendation. Subsequently, light the flame and regulate the flow of
fuel and oxidant, adjust the burner and nebulizer flow rate for maximum percent
absorption and stability, and balance the photometer. Run a series of standards of the
element under analysis and construct a calibration curve by plotting the concentrations
of the standards against the absorbance. For those instruments which read directly in
concentration set the curve corrector to read out the proper concentration. Aspirate the
samples and determine the concentrations either directly or from the calibration curve.
Standards must be run each time a sample or series of samples are run.
9.1.1 Calculation Direct determination of liquid samples: Read the metal value in
mg/l from the calibration curve or directly from the readout system of the
instrument
9.1.1.1 If dilution of sample was required:
mg/1 metal in sample = A
where:
A = mg/l of metal indiluted aliquot from calibration curve
B = ml of dcionized distilled water used for dilution
C = ml of sample aliquot
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V I 2 For samples containing particulates
mg/i metal m sample = A
where.
A = mg/1 of metal in processed sample from calibration curve
V = final volume of the processed sample in ml
C = ml of sample aliquot processed
9.1.3 For solid samples: report all concentrations as mg/kg dry weight
9.1.3.1 Dry sample:
A x V
mg metal/kg sample « —g—
where:
A = mg/1 of metal in processed sample from calibration curve
V= final volume of the processed sample in ml
D= weight of dry sample in grams
9.1.3.2 Wet sample:
A X V
mg metal/kg sample = w x p
where:
A = mg/1 of metal in processed sample from calibration curve
V = final volume of the processed sample in ml
W = weight of wet sample in grams
P = % solids
9.2 Special Extraction Procedure: When the concentration of the metal is not sufficiently
high to determine directly, or when considerable dissolved solids are present in the
sample, certain metals may be chelated and extracted with organic solvents. Ammonium
pyrrolidine dithiocarbamate (APDC) (see footnote) in methyl isobutyl ketone (MIBK) is
widely used for this purpose and is particularly useful for zinc, cadmium, iron,
manganese, copper, silver, lead and chromium**. Tri-valent chromium does not react
with APDC unless it has first been converted to the hexavalent form [Atomic Absorption
Newsletter 6, p 128 (1967)] This procedure is described under method 218 3
The name ammonium pyrrolidine dithiocarbamate (APDC) is somewhat ambiguous and should more
properly be called ammonium. I - pyrrolidine c.irhodiiluo.iie (A I'CO). CAS Registry No 5108-96-S
(*
MCTAI.S-14
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Aluminum, beryllium, b.tmnn .mil •.Konlium .iko do not rc.icl with AI'DC While the
Al'DC-MIBK chelatmg-solvent system can be used satisfactorily, it is possible to
experience difficulties (See Note 9)
NOTE 9; Certain metal chelates, nianganese-Al'DC in particular, arc not stable in
M1BK and will redissolve into the aqueous phase on standing The extraction of other
metals is sensitive to both shaking rate and time. As with cadmium, prolonged extraction
beyond 1 minute, will reduce the extraction efficiency, whereas 3 minutes of vigorous
shaking is required for chromium.
Also, when multiple metals are to be determined either larger sample volumes must be
extracted or individual extractions made for each metal being determined. The acid form
of APDC-pyrroIidine dithiocarbamic acid prepared directly in chloroform as described
by Lakanen, [Atomic Absorption Newsletter 5, p 17 (1966)], (see 7.7.1) has been found
to be most advantageous. In this procedure the more dense chloroform layer allows for
easy combination of multiple extractions which are carried out over a broader pH range
favorable to multielement extractions. Pyrrolidine dithiocarbamic acid in chloroform is
very stable and may be stored in a brown bottle in the refrigerator for months. Because
chloroform is used as the solvent, it may not be aspirated into the flame. The following
procedure is suggested.
9.2.1 Extraction procedure with pyrrolidine dithiocarbamic «icid (PDCA) in
chloroform.
9.2.1.1 Transfer 200 ml of sample into a 250 ml separatoiy funnel, add 2 drops
bromphenol blue indicator solution (7.7.3) and mix.
9.2.1.2 Prepare a blank and sufficient standards in the same manner and adjust
the volume of each to approximately 200 ml with deionized distilled
water. All of the metals to be determined may be combined into single
solutions at the appropriate concentration levels.
9.2.1.3 Adjust the pH by addition of 2N NH«OH solution (7.7.2) until a blue
color persists. Add HQ (7.7.4) dropwise until the blue color just
disappears; then add 2.0 ml HC1 (7 7.4) in excess. The pH at this point
should be 2.3. (The pH adjustment may, be made with a pH meter
instead of using indicator.)
9.2.1.4 Add 5 ml of PDCA-chloroform reagent (7.7.1) and shake vigorously
for 2 minutes. Allow the phases to separate and drain the chloroform
layer into a 100 ml beaker. (See NOTE 10.)
NOTE 10: If hexavalent chromium is to be extracted, the aqueous
phase must be readjusted back to a pH of 2.3 after the addition of
PDCA-chloroform and maintained at that pH throughout the
extraction. For multielement extraction, the pH may adjusted upward
after the chromium has been extracted
Ml I AI S-15
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9 2 15 Add a second portion of 5 ml PDC A-chloroform reagent (7 7 1) and
shake vigorously for 2 minutes Allow the pluses to separate and
combine the chloroform phase with that obtained in step (9 2 1.4)
9 2 16 Determine the pH of ttic aqueous phase and adjust to 4 5
9.2 1 7 Repeat step (9 2 1 4) again combining the solvent extracts
9.2.1.8 Readjust the pH to 5.5, and extract a fourth time. Combine all extracts
and evaporate to dryness on a steam bath.
9.2.1.9 Hold the beaker at a 45 degree angle, and slowly add 2 ml of cone
distilled nitric acid, rotating the beaker to effect thorough contact of
the acid with the residue.
9.2.1.10 Place the beaker on a low temperature hotplate or steam bath and
evaporate just to dryness.
9.2.1.11 Add 2 ml of nitric acid (1:1) to the beaker and heat for 1 minute. Cool,
quantitatively transfer the solution to a 10 ml volumetric flask and
bring to volume with distilled water. The sample is now ready for
analysts.
9.2.2 Prepare a calibration curve by plotting absorbance versus the concentration of the
metal standard (ug/1) in the 200 ml extracted standard solution. To calculate
sample concentration read the metal value in ug/1 from the calibration curve or
directly from the readout system of the instrument. If dilution of the sample was
required use the following equation:
mg/1 metal in sample = Z
where:
Z = ug/1 of metal in diluted aliquot from calibration curve
B — ml of deionized distilled water used for dilution
C = ml of sample aliquot
Furnace Procedure: Furnace devices (nameless atomization) are a most useful means of
extending detection limits. Because of differences between various makes and models of
satisfactory instruments, no detailed operating instuctions can be given for each
instrument. Instead, the analyst should follow the instructions provided by the
manufacturer of his particular instrument and use as a guide the temperature settings
and other instrument conditions listed on the individual analysis sheets which are
recommended for the Perkin-Elmer HGA-2100. In addition, the following points may be
helpful.
9 3 1 With flamc[css atomization, background concction becomes of high importance
especially below 350 hid 1 Ins is because certain dimples, when atomized, may
absorb oi scaltei li^ln iiom Ih< hollow v.iiIhhU lamp li L.m bo caused by the
presence o! gaseous molecular species, sail particulcs, or smoke in I he sample
m
Mfll'Al.S-U.
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beam If no correction is nude, sample absorbaiKe will bo greater dun il should be,
and (lie analytical result will be erroneously high
9 3 2 If during atomization all the analytc is not volatilized and removed from the
furnace, memory effects will occur This condition is de|>cndeiit on several factors
such as the volatility of the element and Us chemical form, whether pyrolytic
graphite is used, the rate of atomization and furnace design. If this situation is
detected through blank burns, the tube should be cleaned by operating the furnace
at full power for the required time period as needed at regular intervals in the
analytical scheme.
9.3.3 Some of the smaller size furnace devices, or newer furnaces equipped with feedback
temperature control (Instrumentation Laboratories MODEL 555, Perkin-EImer
MODELS HGA 2200 and HGA 76B, and Varian MODEL CRA-90) employing
faster rates of atomization, can be operated using lower atomization temperatures
for shorter time periods than those listed in this manual.
9.3.4 Although prior digestion of the sample in many cases is not required providing a
representative aliquot of sample can be pipeted into the furnace, it will provide for a
more uniform matrix and possibly lessen matrix effects.
9.3.5 Inject a measured microliter aliquot of sample into the furnace and atomize. If the
concentration found is greater than the highest standard, the sample should be
diluted in the same acid matrix and reanalyzed. The use of multiple injections can
improve accuracy and help detect furnace pipetting errors.
9.3.6 To verify the absence of interference, follow the procedure as given in part 5.2.1.
9.3.7 A check standard should be ran approximately after every 10 sample injections.
Standards are run in part to monitor the life and performance of the graphite tube.
Lack of reproducibility or significant change in the signal for the standard
indicates that the tube should be replaced. Even though tube life depends on
sample matrix and atomization temperature, a conservative estimate would be that
a tube will last at least 50 firings. A pyrolytic-coating would extend that estimate
by a factor of 3.
9.3.8 Calculation-For determination of metal concentration by the furnace: Read the
metal value in ug/1 from the calibration curve or directly from the readout system
of the instrument.
9.3.8.1 If different size furnace injection volumes are used for samples than for
standards:
ug/l of metal in sample = Z
where:
Z — "g/l of metal re.«c! from L.ilibr.ition uirvc or ii .iiliuii svsiein
S - til volume standard injected mio Itnn.itr lot l.»JiI>i.i!ioi> <. in vc
U = ul volume of sample injected for analysis
(+)
MCTALS-17
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9 3 8.2 II dilution ot s.nnplc was icquireil but sjiuple injection volume same as
for standard
tig/1 of metal in sample = Z
where.
Z = ug/1 metal in diluted aliquot from calibration curve
B = ml of deionized distilled water used for dilution
C = ml of sample aliquot
9.3.9 For sample containing particulates:
/ v
ug/1 of metal in sample = Z I ^
where:
Z = ug/1 of metal in processed sample from calibration curve (See 9.3.8.1)
V = final volume of processed sample in ml
C = ml of sample aliquot processed
9.3.10 For solid samples: Report all concentrations as mg/kg dry weight
9.3.10.1 Dry sample:
\ 1,000 / v
mg metal/kg sample = ¦
D
where:
Z •= ug/l ofmetal in processed sample from calibration curve^See 9.3.8.1)
V ¦= final volume of processed sample in ml
D = weight of dry sample in grams
9.3.10.2 Wet sample:
( — V
\1.000 J
mg metal/kg sample =
W x P
where:
Z = i/g/1 of metal in processed sample from calibration curve (See V 3 8 I)
V final volume ol processed sample in ml
W -= weigin ol wel sample m giams
1' = % solids
M1.TA1.S-IK
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10 Quality Control For Drinking Water Analysis
10.1 Minimum requirements
10.1.1 All quality control data should be maintained and available for easy
reference or inspection
10 1.2 An unknown performance sample (when available) must be analyzed once
per year for the metals measured. Results must be within the control limit
established by EPA. If problems arise, they should be corrected, and a
follow-up performance sample should be analyzed.
10.2 Minimum Daily control
10.2.1 After a calibration curve composed of a minimum of a reagent blank and
three standards has been prepared, subsequent calibration curves must be
verified by use of at least a reagent blank and one standard at or near the
MCL. Daily checks must be within ± 10 percent of original curve.
10.2.2 If 20 or more samples per day are analyzed, the working standard curve must
be verified by running an additional standard at or near the MCL every 20
samples. Checks must be within ± 10 percent of original curve.
10.3 Optional Requirements
10.3.1 A current service contract should be in effect on balances and the atomic
absorption spectrophotometer.
10.3.2 Class S weights should be available to make periodic checks on balances.
10.3.3 Chemicals should be dated upon receipt of shipment and replaced as needed
or before shelf life has been exceeded.
10.3.4 A known reference sample (when available) should be analyzed once per
quarter for the metals measured. The measured value should be within the
control limits established by EPA.
10.3.5 At kast one duplicate sample should be run every 10 samples, or with each
set of samples to verify precision of the method. Checks should be within the
control limit established by EPA.
10.3.6 Standard deviation should be obtained and documented for all
measurements being conducted.
10.3.7 Quality Control charts or a tabulation of mean and standard deviation
should be used to document validity of data on a daily basis.
mi:tals-i9
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United Suite*
Gnvironmcni.il Protection
Aqpucy
Environmental Monitoring ontf
Suppom laboratory
Oncumnti OH 45200
Ni;S«MfCh
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determination of trace elements
Background must be measured
adiacent to analyle lines on samples
during analysis The position selected
(or the background intensity
measurement, on either or both sides
of the analytical line, will be
determined by the complexity of the
spectrum adjacent to the analyle line
The position used must be free of
Spectral interference and reflect the
same change in background
intensity as occurs at the analyle
wavelength measured. Background
correction is not required in cases of
line broadening where a background
correction measurement would
actually degrade the analytical result
The possibility of additional
interferences named in 5.1 (and tests
for their presence as described in 5.2)
should also be recognized and
appropriate corrections made.
3. Definitions
3.1 Dissolved — Those elements
which will pass through a 0.45 j/m
membrane filter.
3.2 Suspended — Those elements
which are retained by a 0.45 ftm
membrane filter.
3.3 Total — The concentration
determined on an unfiltered sample
following vigorous digestion (9.3), or
the sum of the dissolved plus
suspended concentrations. (9.1 plus
9.2.)
3.4 Total recoverable — The
concentration determined on an
unfiltered sample following treatment
with hot dilute mineral acid (9.4).
3.5 Instrumental detection limit —
The concentration equivalent to a
signal, due to the khafyte, which is
equal to three' times the standard
deviation of a series of ten replicate
measurements of a reagent blank
signal at the same wavelength
3.6 Sensitivity — The slope of the
analytical curve, i e functional
relationship between emission
intensity and concentration.
3.7 Instrument check standard — A
multielement standard of known
concentrations prepared by the
analyst to monitor "8nd verify
instrument performance on a daily
basis (See ? G I)
3.6 Interference check sample — A
solution containing both interfering
and analyte elements of known
concentration that can be used to
venly background and mtcrelemcnt
correction (actors (See 7 6 2)
3 9 Quality control sample — A
solution obtained from an outside
source having known, concentration
values to be used to verify the
calibration standards (See 7 6 3)
3.10 Calibration standards — a
series of know standard solutions
used by the analyst for calibration of
the instrument (i e . preparation of the
analytical curve) (See 7 4)
3.11 Linear dynamic range — The
concentration range over which the
analytical curve remains linear.
3.12 Reagent blank — A volume of
deionized, distilled water containing
the same acid matrix as the
calibration standards carried through
the entire analytical scheme. (See
7.5.2}
3.13 Calibration blank — A volume
of deionized. distilled water acidified
with HNOi and HCI. (See 7.5.1)
3.14 Method of standard addition —
The standard addition technique
involves the use of the unknown and
the unknown plus a known amount of
standard. (See 10.6.1}
4. Safety
4.1 The toxicity or carcinogenicity of
each reagent used in this method has
not been precisely defined however,
each chemical compound should be
treated as a potential health hazard.
From this viewpoint, exposure to
these chemicals must be reduced to
the lowest possible level by whatever
means available. The laboratory is
responsible for maintaining a current
awareness file of OSHA regulations
regarding the safe handling of the
chemicals specified in this method. A
reference file of material data
handling sheets should also be made
available to all personnel involved in
the chemical analysis Additional
references to laboratory safety are
available and have been identified
(14.7. 14 8 and 14.9) for the
information of the analyst
5. Interferences
5 1 Several types of interference
effects may con(ril>uic to mftccaracies
in ihe dcicrmmnnon of trace
elements They can be summarized as
follows
5 11 Spectral interferences can be
categorized as 1) overlap of a spectral
(me from another clement 2)
unresolved overlap of molecular ba
spectra. 3) background contribution
from continuous or recombination
phenomena, and 4) background
contribution from stray light from it
line emission of high concentration
elements The'first of these effects
can be compensated by utilizing a
computer correction ol the raw data
requiring the monitoring and
measurement of the interfering
element. The second effect may
require selection of an alternate
wavelength. The third and fourth
effects can usually be compensated 1
a background correction adjacent to
the analyte line. In addition, users of
simultaneous multielement
instrumentation must assume the
responsibility of verifying the absence
of spectral interference from an
element that could oocur in a sample
but for which there is no channel in
the instrument array. Listed in Table
are some interference effects for the
recommended wavelengths given in
Table 1. The data in Table 2 are
intended for use only as a
rudimentary guide for the indication of
potential spectral interferences. For
this purpose, linear relations between
concentration and intensity for the
anatytes and the interferents can be
assumed.
The interference information, which
was collected at the Ames Laboratory,'
is expressed at'analyte concentration
eqivalents (i.e. false analyte concen-
trations] arising from 100 mg/L of the
interferent element. The suggested use
of this information is as follows:
Assume that arsenic (at 193.696 nm)
is to be determined in a sample
containing approximately 10 mg/L of
aluminum. According to Table 2.100
mg/L of aluminum would yield a false
signal for arsenic equivalent to
approximately 1.3 mg/L Therefore,
10 mg/L of aluminum would result in
a false signal for arsenic equivalent to
approximately 0.13 mg/L The reader
is cautioned that other analytical
systems may exhibit somewhat
different levels of interference than
those shown in Table 2. and that the
interference effects must be evaluated
for each individual system
Only those interferents listed wer<>
investigated and the blank spaces m
Table 2 indicate that measurable inter
Icrcnces were not observed for ihe
• ntc'fercnt concentrations listed m
Table 3 Generally interferences weic
discernible if they produced peaks or
background shifts corresponding to
2-5% of the peaks generated by the
Ames L»txvMory USOOE Iowa S<*ie Un»ve*stiv
Amci law# 500? I
Dec 1982
Me(
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analyte concentrations also listod in
Table 3
Al prcsont. information on (tie listed
silver and potassium wavelengths are
not available but it has been reported
that second order energy Irom the
magnesium 383 231 nm wavelength
interferes with the listed potassium line
at 766 491 nm
5.1.2 Physical interferences are
generally considered (o be effects
associated with the sample nebuliza-
lion and transport processes. Such
properties as change in viscosity and
surface tension can cause significant
inaccuracies especially in samples
which may contain high dissolved
solids and/or acid concentrations. The
use of a peristaltic pump may lessen
these Interferences, ff these types of
interferences are operative, they must
be reduced by dilution of the sample
and/or utilization of standard addition
techniques. Another problem which
can occur from high dissolved solids
is salt buildup at the tip of the
nebulizer. This affects aersol flow-rate
causing instrumental drift Wetting
the argon prior to nebulization, the
use of a tip washer, or sample dilution
have been used to control this
problem. Also, it has been reported
that better control of the argon flow
rate improves instrument
performance. This Is accomplished
with the use of mass flow controllers.
S.J.3 Chemical Interferences a re
characterized by molecular compound
formation, ionization effects and
solute vaporization effects. Normally
these effects are not pronounced with
the ICP technique however, if
observed they can be minimized by
careful selection of operating
conditions (that h incident power,
observation position and so forth) by
buffering of the sample by matrix
matching, and by standard addition
procedures. These types of
interferences can be highly dependent
on matrix type and the specific
analyte element
5.2 It is recommended that
whenever a new or unusual sample
matrix is encountered, a series of
tests be performed prior to reporting
concentration data for analyte
elements These tests, as outlined in
5 2 1 through 5 2 4, will ensure ihe
analyst that neither positive nor
negative interference effects arc
operative on any of the analyte el-
ements thereby distorting the
accuracy of the reported values.
.5.2.1 Serial dilution—If the analyte
:oncentration is sufficiently high (min-
imally a factor of 10 dliovc the instru
mental detection limit alter dilution)
an analysis of a dilution should agree
within 5 % of the original determine
Hon (or within some acceptable con
trol limit (14 3) that has been csiab
lishod for that matrix) If not, a
chemical or physical interference ef-
fect should be suspected
5.2.2 Spike addition—The recovery
of a spike addition added at a
minimum level of 10X the in-
strumental detection limit (maximum
100X) to the original determination
should be recovered to within 90 to
110 percent or within the established
control limit for that matrix. If not. a
matrix effect should be suspected. The
use of a standard addition analysis
procedure can usually compensate for
this effect. Caution; The standard ad-
dition technique does not detect coin-
cident spectral overlap. If suspected,
use of computerized compensation, an
alternate wavelength, or comparison
with an alternate method is recom-
mended. (See 5.2.3)
5.2.3 Comparison with alternate
method of analysis—When investi-
gating a new sample matrix, compari-
son tests may be performed with other
analytical techniques such as atomic
absorption spectrometry, or other
approved methodology.
5.2.4 Wavelength scanning of
analyte line region—If the appropriate
equipment is available, wavelength
scanning can be performed to detect
potential spectral interferences.
6. Apparatus
6.1 Inductively Coupled Plasma-
Atomic Emission Spectrometer
6.1. f Computer controlled atomic
emission spectrometer with background
correction.
6.1.2 Radiofrequency generator
6.1.3 Argon gas supply, welding
grade or better
6.2 Operating conditions — Because
of the differences between various
makes and models of satisfactory
instruments, no detailed operating
instructions can be provided Instead
the analyst should follow the
instructions provided by tlie
manufacturer of the particular
instrument Sensitivity, instrumental
detection limit, precision, linear dy-
namic range, and interference effects
must be investigated and established
for each individual analyte line on that
particular instrument It is the
responsibility of the analyst to verify
tlvil tlie instrument configuration .ind
operating Conditions used satisfy tt»e
analytical requirements and to
maintain quality control data
confirming instrument performance
and analytical results
7. Reagents and standards
7.1 Acids used in the preparation
of standards and for sample processing
must be ultra-high purity grade or
equivalent. Redistilled acids are
acceptable
7.1.1 Acetic acid. conc. (sp gr 1.06).
7.1.2 Hydrochloric acid, conc. (sp gr
1.19).
7.1.3 Hydrochloric acid. (1+1): Add
500 mL conc. HCI (sp gr 1.19) to 400
mL deionized, distrilled water and
dilute to 1 liter.
7.1.4 Nitric acid. conc. (sp gr 1.41 J.
7.1.5 Nitric acid.(1+1): Add 500 mL
conc. HNOj (sp. gr 1.41] to 400 mL
deionized, distilled water and dilute to
1 liter.
7.2 Dionized, distilled water: Prepare
by passing distilled water through a
mixed bed of cation and anion ex-
change resins. Use deionized, distilled
water for the preparation of all
reagents, calibration standards and as
dilution water. The purity of this water
must be equivalent to ASTM Type II
reagent water of Specification 0 1193
(14.6).
7.3 Standard stock solutions may be
purchased or prepared from ultra high
purity grade chemicals or metals. All
salts must be dried for 1 h at 10S°C
unless otherwise specified
(CAUTION: Many metal salts are ex-
tremely toxic and msy be fatal if swal-
lowed Wash hands thoroughly after
handling] Typical stock solution pre-
paration procedures follow
7.3.1 Aluminum solution, stock. 1
mL = 100 //g Al' Dissolve 0.100 g of
aluminum metal in an acid mixture of 4
mL of (1+1) HQ and 1 mL of conc. HNOj
in a beaker. Warm gently to effect
solution When solution is complete,
transfer quantitatively to a liter (task,
add an additional 10 mL of (1 ~ 1) HCI
.ind dilute to 1 000 ml with deionized
distilled water
7 3 2 Antimony solution stock 1 mL
= 100 fjg Sb Dissolve 0 2669 g K
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7.3.3 Arsenic solution. stock. I mL 1
tOO tig As Dissolve 0 1320 0 of As?Oj
in 100 rnL of dcionued, distilled water
containing 0 4 g NaOH Acidify the
solution with 2 mL cone HNOj and
dilute 10 1.000 mL with deionized,
distilled water
7.3.4 Barium solution, stock, 1 mL
s 100 fig 8a Dissolve 0 1516 g SaCI?
(dried at 250°C (or 2 hrs) in 10 mL
deionized. distilled water with 1 mL
(1 + 1| HCI. Add 100 ml (1 +1) HCI
and dilute to 1,000 mL with deiomzed,
distilled water.
7.3.5 Beryllium solution, stock. I
mL - 100 /A} Be Do not dry. Dis-
solve 1.966 g BeS0< • 4 4H2O, in
deionized, distilled water, edd 10.0 mL
conc. HNOj and dilute to 1,000 mL
with deionized. distilled water.
7.3.6 Boron solution, stock. 1 mL
c 100 fig B: Do not dry. Dissolve
0.5716 g anhydrous HjBOj in deionized
distilled water dilute to 1.000 mL
Use a reagent meeting ACS specifica-
tions, keep the bottle tightly stoppered
and store in a desiccator to prevent
the entrance of atmospheric moisture.
7.3.7 Cadmium solution, stock. 1
mL = 100 >
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7 4.5 Mixed standard solution V—
Antimony boron, magnesium silver
and thallium
NOTE I II tlie addition of silver
to the recommended acid combination
resulls m an initial precipitation,
add 15 ml o( deionued distilled
water and warm the flask until the
solution clears Cool and dilute lo 100
ml with deionized. distilled water For
this acid combination the silver con-
centration should be limited to 2
mg/^. Silver under these conditions
is stable in a tap water matrix
for 30 days. Higher concentrations
of silver require additional HCI.
7.5 Two types of blanks are required
I or the analysis The calibration blank
(3.13) is used in establishing the
analytical curve while (he reagent
blank (3.12) is used to correct for
possible contamination resulting from
varying amounts of the acids used in
the sample processing.
7.5. 1 The calibration blank is pre-
pared by diluting 2 ml of (1+1) HNOi
and 10 ml of (1*1) HCI to 100 mL
with deionized. distilled water. (See
Note 6.) Prepare a sufficient quantity
to be used to flush the system be-
tween standards and samples.
7.5.2 The reagent blank must con-
contain all the reagents and in the
same volumes as used in the pro-
cessing of the samples. The reagent
blank must be carried through the
complete procedure and contain the
same acid concentration in the final
solution as the sample solution
used for analysis.
7.6 In addition to the calibration
standards, an instrument check stan-
dard (3.7), an interference check
sample (3.8) and a quality control
sample (3.9) are also required for the
analyses.
7.6.1 The instrument check standard
is prepared by the analyst by com-
bining compatible elements at a con-
centration equivalent to the midpoint
of their respective calibration curves.
(See 12.1. t)
7.6.2 The interference check sample
is prepared by the analyst in the
following manner. Select a
representative sample which contains
minimal concentrations of the
anafytes of interest by known con-
centration of interfering elements that
will provide an adequate test of the
correction (actors Spike the sample
with the elements of interest at the
approximate concentration of either
tOO fjq/l- or 5 times the estimated
detection limits given in Table 1 (For
effluent samples of expected high
concentrations, spike at an
appropriate level) If the type of
samples analyzed aie varied, a
Synthetically prepared sample may be
used if the above criteria and intent
are met A limited supply of a
synthetic interference check sample
will be available from the Quality
Assurance Branch of EMSL-
Cincinnau (See 12 12)
7.6.3 The Quality control sample
should be prepared in the same acid
matrix as the calibration standards
at a concentration near 1 mg/L and in
accordance with the instructions
provided by the supplier. The Quality
Assurance Branch of EMSL-Cincinnati
will either supply a quality control
sample or information where one of
equal quality can be procured. (See
12.1.3)
8. Sample handling an
preservation
8.1 For the determination of trace
elements, contamination and loss are
of prime concern. Oust in the labora-
tory environment, impurities in
reagents and impurities on laboratory
apparatus which the sample contacts
are all sources of potential
contamination. Sample containers can
introduce either positive or negative
errors in the measurement of trace
elements by (a) contributing con-
taminants through leaching or surface
desorption and (b) by depleting
concentrations through adsorption.
Thus the collection and treatment of
the sample prior to analysis requires
particular attention. Laboratory
glassware including the sample bottle
(whether polyethylene polyproplyene
or FEP-fluorocarbon) should be
thoroughly washed with detergent
and tap water; rinsed with (1+1) nitric
acid, tap water. (1+1) hydrochloric
acid, tap ar.d finally deionized, distilled
water in that order (See Notes 2 and
31-
NOTE 2. Chromic acid may be useful to
remove organic deposits from glass-
ware; however, the analyst should be
be cautioned that the glassware must
be thoroughly rinsed with water to
remove Ihe last traces of chromium
This is especially important if chromium
is to be included in the analytical
scheme A commercial product NOCH
ROMIX dvailable from Godax Labor
atones, 6 Varicfc Si. New York. NY
10013. may be used in place of
chromic acid Chomic acid should not
be used with plastic bottles
NOTE 3 If it can be documented through
an active analyiical quality control
program using spiked samples and re-
agent blanks, that certain steps in the
cleaning procedure are not required for
routine samples, those steps may be
eliminated from the procedure
8.2 Before collection of ihe sample a
decision must be made as to the type
of data desired, that is dissolved,
suspended or total, so that the appro-
priate preservation and pretreatment
steps may be accomplished. Filtration,
acid preservation, etc, are to be per-
formed at the time the sample is
collected or as soon as possible
thereafter
8.2.1 For the determination of dis-
solved elements the sample must be
filtered through a 0.45-//m membrane
filter as soon as practical after collec-
tion. (Glass or plastic filtering appara-
tus are recommended to avoid possi-
ble contamination.) Use the first 50-
100 mL to rinse the filter flask. Ois-
card this portion and collect the
required volume of filtrate. Acidify the
filtrate with (1+1) HNOi to a pH of 2
or less. Normally, 3 mL of (1+1) acid
per liter should be sufficient to pre-
serve the sample.
8.2.2 For the determination of sus-
pended elements a measured volume
of unpreserved sample must be fil-
tered through a 0.45-pm membrane
filter as soon as practical after
collection. The filter plus suspended
material should be transferred to a
suitable container for storage and/or
shipment. No preservative is required.
8.2.3 For the determination of total
or total recoverable elements, the
sample is acidified with (1+t) HNOi
to pH 2 or less as soon m possible,
preferable at the time bf collection.
The sample (s not filtered before
processing.
9. Sample Preparation
9.1 For the determinations of dis-
solved elements, the filtered,
preserved sample may often be
analyzed as received. The acid matrix
and concentration of the samples and
calibration standards must be the
same. (See Note 6.) If a precipitate
formed upon acidification of the
sample or during transit or storage, it
must be redissolved before the
analysis by adding additional acid
and/or by heat as described in 9 3
9 2 For the determination of sus-
pended elements, transfer the mem-
brane filter containing the insoluble
material to a 150-mL Griffin beaker
and add 4 mL cone HNOs Cover the
Melah-24
Dec 1982
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beaker with a watch glass and heat
geruly The warn acid will soon dis-
solve the membrane
Increase the temperature of the
hot plate and digest the material
When the acid has nearly evaporated,
cool the beaker and watch glass and
add another 3 ml of cone HNOj
Cover and continue heating until the
digestion is complete, generally indi-
cated by a light colored digestate
Evaporate to near dryness {2 mU, cool,
add 10 ml HCI (1+1) and 15 ml
de ionized. distilled water per 100 mL
dilution and warm the beaker gently
(or 1S rnin. to dissolve any precipi-
tated or residue material. Allow to
cool, wash down the watch glass and
beaker walls with deionized distilled
water and filter the sample to remove
insoluble material that could dog the
nebulizer. (See Note 4.} Adjust the
volume based on the expected con-
centrations of elements present. This
volume will vary depending on the
elements to be determined (See Note
6). The sample is now ready for
analysis. Concentrations so determined
shall be reported as "suspended."
NOTE 4: In place of filtering, the
sample after diluting and mixing may
be centrifuged or allowed to settle by
gravity overnight to remove insoluble
material
9.3 For the determination of total
elements, choose a measured, volume
of the well mixed acid preserved
sample appropriate tor the expected
level of elements and transfer to a
Griffin beaker. {See Note S.) Add 3 mL
of conc. HNO». Place the beaker on
a hot plate and evaporate to near dry-
ness cautiously, making certain that
the sample does not boil and that no
area of the bottom of the beaker is
allowed to go dry. Cool the beaker and
add another 5 mL portion of conc.
HNOj. Cover the beaker with a watch
glass and return to the hot plate.
Increase the temperature of the hot
plate so that a gentle reflux action
occurs. Continue heating, adding addi-
tional acid as necessary, until the
digestion is complete (generally indi-
cated when the digestate is light
in color or does not change in appear-
ence with continued refluxing.) Again,
evaporate to near dryness end cool
the beaker. Add 10 mL of 1+1 HCI
and 15 mL of deionized. distilled
water per 100 mLdf final solution
and warm the beaker gently lor 15
mm to dissolve any precipitate or
residue resulting from evaporation
Allow to cool, wash down the beaker
walls and watch glass with deioniied
distilled water and filter the sample to
remove insoluble material that could
clog the nebulirer {See Note <1 ) Adjust
the sample to a predetermined volume
based on the expected concentrations
of elements present The sample is
now leady for analysis (See Note 6)
Concentrations so determined shall be
reported as "total "
NOTE 5 If low determinations of
boron are critical, quartz glassware
should be use.
NOT£ 6: If the sample analysis solution
has a different acid concentration
from that given in 9 4. but does not
introduce a physical interference or
affect the analytical resuli. the same
calibration standards may be used.
9.4 For the determination of total
recoverable elements, choose a mea-
sured volume of a well mixed, acid
preserved sampfe appropriate for the
expected level of elements and trans-
fer to a Griffin beaker. (See Note 5.)
Add 2 mL of (1*1) HNOj and 10 mL
of (1*1) HCI to the sample and heat
on a steam bath or hot pfate until the
volume has been reduced to near 25
mL making certain the sample does
not boiL After this treatment cool
the sample and filter to remove inso-
luble material that oould clog the
nebulizer. (Sea Note 4.) Adjust the
volume to 100 mL and mix. The sample
is now ready for analysis. Concentra-
tions so determined shall be reported
as "total."
10. Procedure
10.1 Set up instrument with proper
operating parameters established in
6.2. The instrument must be allowed
to become thermally stable before be-
ginning. This usually requires at least
30 min. of operation prior to calibra-
tion.
10.2 Initiate appropriate operating
configuration of computer.
10.3 Profile and calibrate instru-
ment according to instrument
manufacturer's recommended
procedures, using the typical mixed
calibration standard solutions
described in 7.4. Flush the system
with the calibration blank (7.5.1)
between each standard (See Note 7.)
(The use of the average intensity of
multiple exposures for both
standardiration and sample analysis
has been found to reduce random
error )
NOTE 7 For boron concentrations
greater than 500 vg/l extended (lush
times of 1 to 2 min may be required
10.4 Before beginning the sample
run. reanalyie the highest mixed
calibration standard bs if it were a
sample Concentration values obtamec
should not deviate Irom the actual
values by more than ± 5 percent
(or the established control limits
whichever is tower) If ihey do. follow
the recommendations of the instru-
ment manufacturer to correct for this
condition
10.5 Begin the sample run flushing
the system with the calibration blank
solution (7.5.1) between each sample.
(See Note 7.) Analyze the instrument
check standard (7.6.1) and the calibra-
tion blank (7.5.1) each 10 samples.
10.6 If it has been found that
method of standard addition are
required, the following procedure is
recommended.
10.6.1 The standard addition tech-
nique (14.2) involves preparing new
standards in the sample matrix by
adding known amounts of standard to
one or more aliquots of the processed
sampfe solution. This technique com-
pensates for a sample constituent that
enhances or depresses the anatyte
signal thus producing a different slope
from that of the calibration standards.
It will not correct for additive inter-
ference which causes a baseline shift.
The simplest version of this technique
is (he single-addition method. The
procedure is as follows. Two identical
aliquots of the sample solution, each
of volume V„ are taken. To the
first (labeled A) is added a small
volume V* of a standard analyte >
solution'©! concentration c,. To the
second (labeled B) is added the same
volume V, of the solvent The analy-
tical signals of A and B are measured
and corrected for nonanafyte signals.
The unknown sample concentration
c. is calculated:
c*= SaV&ia.
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3. The interference effect most be
constant over the working range of
concern
4 The signal must be corrected (o>
any additive interference
11. Calculation
11.1 Reagent blanks (7 5.2) should
be subtracted from all samples This is
particularly important for digested
samples requiring large quantities of
acids to complete the digestion.
11.2 If dilutions were performed,
the appropriate factor must be applied
to sample values.
11.3 Data should be rounded to the
thousandth place and all results
should be reported in mg/L up to
three significant figures.
12. Quality Control
(Instrumental)
12.1 Check the instrument
standardization by analyzing
appropriate quality control check
standards as follow;
12.1.1 Analyze an appropriate
instrument check standard (7.6.1)
containing the elements of interest at
a frequency of 10%. This check
standard is used to determine
instrument drift. If agreement is not
within ±5% of the expected values or
within the established control limits,
whichever is lower, the analysis is out
of control. The analysis should be
terminated, (he problem corrected,
and the instrument recalibrated.
Analyze the calibration blank (7.5.1)
at a frequency of 10%. The result
should be within the established
control limits of two standard devia-
tions of the mean value. If not, repeat
the analysis two more times and
average the three results If the
average is not within the control limit,
terminate the analysis, correct the
problem and recalibrate the
instrument
f2.}.2 To verify interelemenc and
background correction factors analyze
the interference check sample (7.6.2)
at the beginning, end, and at periodic
intervals throughout the sample run
Results should fall within the
established control limits of 1 5 times
the standard deviation-of the mean
value II not. terminate the analysis,
correct the problem and recalibrate
the instrument
12 1 3 A quality control sample
<7 6 31 obtained from an outside
source must first be used for the
initial verification of the calibration
standards A fresh dilution of this
sample shall be anlayted every week
thereafter to monitor their stability II
the results are not within ±5% of the
true value listed for the control
sample, prepare a new calibration
standard and recalibrate the
instrument If this does not correct the
problem, prepare a new stock
standard and a new calibration
standard and repeat the calibration
Precision and Accuracy
13.1 In an EPA round robin phase 1
study, seven laboratories applied the
ICP technique to acid-distilled water
matrices that had been dosed with
various metal concentrates. Table 4
lists the true value, the mean reported
value and the mean % relative
standard deviation.
References
1. Winge, U.K.. V.J. Peterson, and
V.A. Fassel, "Inductively Coupled
Plasma-Atomic Emission
Spectroscopy: Prominent Lines." EPA-
600/4-79-017.
2. Winefordner, J.D., "Trace
Analysis; Spectroscopic Methods for
Elements." Chemical Analysis, Vol.
46, pp. 41-42.
3. Handbook for Analytical Quality
Control in Water and Wastewater
Laboratories. EPA-600/4-79-019.
4. Garbarino, J.R. and Taylor, H.E.,
"An Inductively-Coupled Plasma
Atomic Emission Spectrometry
Method for Routine Water Quality
Testing," Applied Spectroscopy 33.
No. 3(1979).
5. "Methods for Chemical Analysis of
Water and Wastes." EPA-600/4-79-
020.
6. Annual Book of ASTM Standards.
Part 31.
7. "Carcinogens - Working With
Carcinogens," Department of Health.
Education, and Welfare, Public Health
Service, Center for Disease Control.
National Institute for Occupational
Safety and Health. Publication No 77-
206, Aug 1977
8 "OSHA Safety and Health Stan-
dards. General Industry (29 CFR
1910) Occupational Safety and He.iltlt
Admimstiation OSHA 2 206 (Revised
January 1976|
9 'Safety in Academic Chemistry
Laboratories, American Chemical So-
ciety Publication. Committee on
Chemical Safety 3rd Edition. 1979
Meta/s-26
Dec t9S2
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Table t Recommended Wavelengths ' and Estimated Instrumental
Detection Limns
Estimated detection
i
Element
Wavelength, nm
limit, fji
Aluminum
303 215
45
Arsenic
193 696
53
Antimony
206 833
32
Barium
455 403
2
Beryllium
313042
03
Boron
249 773
5
Cadmium
226.502
4
Calcium
317.933
10
Chromium
267.716
7
Cobalt
228.616
7
Copper
324.754
6
Iron
259.940
7
Lead
220.353
42
Magnesium
279.079
30
Manganese
257.610
2
Molybdenum
202.030
8
Nickel
231.604
15
Potassium
766.491
see
Selenium
196.026
75
Silica (SiOi)
288.158
58
Silver
328.068
7
Sodium
588.995
29
Thallium
190.864
4Q
Vanadium
292.402
8
Zinc
213.856
2
' The wavelengths listed are recommended because of their sensitivity and
overall'acceptance. Other wavelengths may be substituted if they can
provide the needed sensitivity and are treated with the same corrective
techniques for spectral interference (See 5. 1. t.j.
*The estimated instrumental detection limits as shown are taken from
'Inductively Coupled Plasma-Atomic Emission Spectroscopy-Prominent
Lines, "EPA-600/4-79-017. They are given as a guide for an instrumental
limit The actual method detection limits are sample dependent and may vary
as the sample matrix varies.
3Highfy dependent on operating conditions and plasma position.
Dec '982
Metats-27
-------
Appendix A
Revision 0
Date: 11/18/83
Page 28 of 30
-------
Table 2 Anatyte Concentration Equivalents (mg/LI Arising From Interfcrents at the 100 mg/t Level
Annlytr Wavelength mil Intcrlcrent
At
Ca
Cr
Cu
fe
Mg
Mn
Nt
h
V
Aluminum
308 215
—
—
—
021
—
—
I 4
Antimony
206 833
0 47
—
29
—
008
—
—
—
25
0 45
Arsenic
193 696
1 3
—
0 44
—
—
—
—
—
—
J t
Barium
455 403
—
—
—
—
—
—
Beryllium
313 042
—
—
—
—
—
—
—
—
0 04
005
Boron
249 773
0 04
—
—
—
0 32
—
—
—
—
—
Cadmium
226502
—
—
003
—
—
002
—
—
Calcium
317.933
—
—
0.08
—
001
0.01
004
—
0.03
0.03
Chromium
267.716
—
—
—
—
0.003
—
004
—
—
0.Q4
Cobalt
228.616
0.03
0005
0.03
0 15
Copper
324.754
—
—
—
—
0.003
—
—
—
0.05
0 02
Iron
259.940
—
—
—
—
—
—
0.12
—
—
—
Lead
220.353
0.17
_
—
—
—
_
Magnesium
279.079
—
0.02
0.11
—
0.13
—
0.25
—
0.07
0.12
Manganese
257.610
0.005
—
0.01
—
0.002
0.002
—
—
—
—
Molybdenum
202.030
0.05
0.03
—
—
—
—
Nickel
231.604
—
—
—
—
—
—
—
—
—
—
Selenium
196.026
0.23
—
—
—
0.09
—
—
—
—
—
Silicon
268.158
0.07
—
0.01
Sodium
588.995
—
—
—
—
—
—
—
0.08
—
Thallium
190.864
0.30
—
—
—
—
—
—
—
—
—
Vanadium
292.402
0.05
_
0.005
—
—
0.02
—
Zinc
213.856
—
—
—
0.14
—
—
0.29
—
—
Table 3. Interfered end Anafyte Elemental Concen-
trations Used (or Interference Measurements
Anafytes
in Table 2.
fmg/LJ
toterferents
(mg/L)
A1
W
A!
1000
As
10
Ca
1000
B
10
Cr
200
8a
;
Cu
200
Be
7
Fe
1000
Ca
i
Mg
1000
Cd
10
Mn
200
Co
1
Nt
200
Cr
1
Tt
200
Cu
1
V
200
Fe
1
Mg
1
Mn
I
Mo
to
Na
JO
Ni
10
Pb
to
Sb
to
Se
JO
Si
1
ft
10
V
1
Zn
w
Mttate-28 Dec tOSI
-------
Appendix A
Revision 0
Date: 11/18/83
Page 29 of 30
-------
Table 4 ICP Precision and Accuracy Data
Sample H ! Sample 0 2 Sample 03
Mean
Mean
Mr an
True
Reported
Mean
True
Reported
Mean
True
Reported
Mean
Value
Value
Percent
Value
Value
Percent
Value
Value
Percent
Element
M9/L
(jg/L
RSD
vg/t
vg/L
RSD
vg/L
vg/L
RSD
Be
750
733
6 2
20
20
98
180
176
5 2
Mn
350
345
2 7
15
15
6 7
100
99
33
V
750
749
1 8
70
69
2 9
170
169
1 1
As
200
208
75
22
19
23
60
63
17
Cr
ISO
149
3 8
10
10
18
50
50
3 3
CL
250
235
5 1
It
11
40
70
67
7 9
Fe
600
594
3.0
20
19
15
180
178
6.0
Al
700
696
56
60
62
33
160
161
13
Cd
50
48
f2
25
29
16
14
13
16
Co
500
512
10
20
20
4.1
120
108
21
Ni
250
245
58
30
28
11
60
55
14
Pb
250
236
16
24
30
32
80
80
14
Zn
200
201
5.6
16
19
45
80
82
94
Se
40
32
21.9
6
8.5
42
10
85
8.3
Not alt elements were analyzed by all laboratories.
Oct 1982
Metals 29
-------
Append i x A
Revision 0
Date: 11/18/83
Paqe 30 of 30
-------
Appendix 8
Revision 0
Date: 11/18/83
Page 1 of 1
APPENDIX B
FIELD EQUIPMENT OPERATION MANUALS*
*Vhll be included later
-------
APPENDIX C
Appendix C
Revision 0
Date: 11/18/83
Page 1 of 7
ALTERNATE METHOD FOR DO/TEMPERATURE MEASUREMENT
-------
Appendix C
Revision 0
Date: 11/18/83
Page 2 of 7
If the DO/temperature probe and meter are inoperrative or malfunctioning,
an estimate of the DO/temperature profile is obtained as follows:
A. Site Operation
1. Determine secchi disk and total depth as usual.
2. Lower the Van Dorn sampler to 1.5 meters above the lake bottom
and trigger to collect a sample. Raise to surface and set on
helicopter platform. Attach a piece of tygon tubing to the out-
let of the Van Dorn sampler and place the end in the bottom of a
glass 300-mL BOD bottle. Fill the bottle to overflowing to
ensure that there are no air bubbles trapped in the bottle.
3. A Hach DO Test Kit (20631-00) is used to determine DO (A copy
of the Hach procedure is included at the end of this appendix).
The sample for DO determination is preserved by adding the contents
of one manganous sulfate powder pillow and one alkaline iodine-azide
reagent powder pillow, carefully stoppering such that no air is
trapped in the bottle, then inverting several times. Allow any flow
to settle (2-3 minutes) then invert several more times. Remove
the stopper, then add the contents of one sulfamic acid powder
pillow. Replace the stopper, being careful not to trap any air
-------
Appendix C
Revision 0
Date: 11/18/83
Page 3 of 7
bubbles, then invert a few times. Label and store the bottle
until back at operational base.
4. Measure the temperature of the remaining water within the Van Oorn
sampler with an NBS-calibrated thermometer. Record the reading.
5. Repeat steps 2 and 3, except obtain the sample from 1.5 meters
below the lake surface.
6. Continue with normal sample collection.
5. Field Station Operations
1. The 00 is determined after completing the monomeric aluminum
extraction.
2. Following the Hach procedure, 200 mL of the preserved DO
sample is titrated with standard 0.1988 N Phenylarsine Oxide
using a Hach digital titrator. The concentration of DO in
the sample is read directly from the digital titrator. Record
results on the lake data form.
-------
Appendix C
Revision 0
Date: 11/18/83
Page 1 of 7
Thoroughly rinse BOD bottles with deionized water prior to
next use.
Continue with normal base operations.
-------
OXYGEN, DISSOLVED
TEST IMPORTANCE
The dissolved oxygen lest is one ol the
mosl important analyses 'or determin-
ing the quality ol natural waters The
ellect ol oxidation wastes on streams
ide suitability of water lor iish and other
organisms and the progress ol scll-
parriicalion can all be measured or
estimated from the dissolved oxygen
content in aerobic sewage treatment
uruts. the minimum odor potential, the
maximum treatment efficiency and the
Stabilization ol wastewater are depend-
ent on maintenance ol adequate dis-
solved oxygen Frequent dissolved
oxygen measurements are essential
for adequate process conlrol
PRINCIPLE
In (he Winkler titration, samples are
treated with manganous sulfate and
alkaline lodide-aztde reagent to (orm
an orange-brown precipitate Sulfamic
acid is added, which reacts with the
iodide lo release free iodine which is
then titrated with PAO (phenylarsine
oxide) or sodium ihiosuilate Tne con-
ccrrttation ol DO is directly propoi-
tional to mi ol titrant used
INTERFERENCES
The electrode method is recom-
mended when testing polluted, turbid
or highly colored waters as well as
water containing tree chlorine, thio-
suffate and organic chemicals
SAMPLE
Since DO concentrations vary con-
siderably with water depth, sludge
deposits, temperature, clarity, now roio
and other natural factors, several
samplings at dillerent sues and deptns
are required for best results
Samples (or the titration method
should be collected in a 300-mi 600
bottle and analyzed on-site U on-site
analysis is not possible, the DO can be
tixed by adding Manganous Sulfate.
Alkaline lodide-Azlde and Sulfamic
Acid Powder Pillows to the sample,
then finishing the titration within a few
hours
Appendix C
Revision 0
Date: 11/18/83
Page 5 of 7
-46-
AMAIYSIS PROCEDURE
U*bt*cd o\)gin is preseni or white if
on gen is Absent
•I \ll««* ihc s-impk to stand until the
fUi*. h is stiiUd, U ivuip ihe iop h df (,f
ihc ^olutiim ele.tr Again m^en the
b»>.tk \.\uil lime*. it> m»\ n»d tcl
*c if J UlUll tile upper li.ill ol the m»Iu
tmn »s ele ir S< v St'ii
* Ktm*»*e the stopper »ml jdd the ion
tcnu of one Sulfamic Aud Powder
1'ilitiu Mt.pl.iw tht stopper hung
i ireful not to trjp tn> .ur bubbles hi
jhc botife md invert scvet \\ umes to
Oxygen, Dissolved
Usinfl 0.1988N PAO
Titration Cartridge
mix The floe wjJI dissolve and leave j
yellow color if dissolved oxygen is
present
6 Mejsure 200 in) of the prepared solu-
tion by filling a clean 250-ml gradu-
ated cylinder lo the 200-tnl mjrk
Pour the solution into a clean 230-ml
Erlcnmeyer flask
7. If performing j hand-held titrjtion.
attach a clean, straight-stem deliver)
tube to 3 0 I988N Phenylarsine Oxide
Titration Cartridge Twist cartridge
onto the utrator body If Digital
Titr.iior is to be attached to .1 labora-
tory stand, use a dean. 90-degree
delivery tube
fc Flush the delivery tube by turning the
coarse delivery knob to eject a fe\*
drops of titrant Reset the counter to
zero and *ipe ihe tip
9 Titrate the, prepared solution with
PAO Titrant. 0 198HN. to a pale yel-
low color
10 Add 2 droppcrfuls of stjrch indicator
solution and *i^trl to mi* A d irk bine
color »ill do * Kip
11 Con (i inn, I Ik hiriuon until the m_>Iu
lion ebingcs Worn d»fV blue to
lOlOfft,^
\2 Kt id iht riunibk r of digits Irorti I he
digit il counter window Divide the
reading by UK) to determine the e
-------
Oiygcn. Dissolved
Using 0 19B8NPAO
Titration Cartridge
NOTE
\llnwinp the Hoi lo selllt Iwin insures
reaction of thi itienusals with .ill of the
dissolved oiv^ui prevail The tloc will
sell[c vert slowly hi ihr salt water and will
usu.ill> require an additional 5 mtnuies
before proceeding with Step 5 Results
will not be jfrccted if the floe refuses to
settle
REAGENTS AND APPARATUS
Cet. No. Description Unll
1072-99 Alkaline lodide-
Ande Reagem
Powder Pillows 100
1071-99 Manganous Sulfate
Powder Pillows 100
14406-01 Phenylarsirte Oxide
Titration Car-
tridge. 0198BN each
349-13 Starch Indicator 4-oz
Solution . . . D8*
1073-99 Sifffamic Acid
Powder Pillows 100
621-00 Bottle, glass-
stoppered. BOO,
300 ml 4
968-00 Clippers, large . . . each
508-46 Cylinder, graduated.
250 ml each
505-46 Flask. Erlenmeyer,
250 ml each
2596-00 Glass Beads ... . 100
Appendix C
Revision 0
Date 11/18/83
Paop 6 of 7
Optional Apporatus
326-00 Cl.imp noldoi e.icn
17205-00 Delivery Tube
straight !>
17342-00 Delivery Tutic
90° 5
563-00 Support Stand each
'targe* sues avoifattc
Optional Larger Reagent Sizes
349-11 Starcn Indicator
Solution pi
349-16
-------
Appendix C
Revision 0
Hate 11/18/83
Pane 7 of 7
Oxygen, Disaolved
Using 1.99N Na,S,0,
Titration Cartridge
NOTE
Allowing the floe to settle twice ensures
reaction of the chemicals »nh all of the
dissolved oxygen present The floe will
settle very slowly m sail water and will
usually require an additional 5 minutes
before proccedtng with Step S Results
witl not be affected if the floe refuses to
settle
REAGENTS AND APPARATUS
Cat. No. Description Unit
1072-99 Alkaline lodide-
Aii de Reagent
Powder Pillows . 100
1071-99 Manganous Sulfate
Powder Pillows . 100
14401-01 Sodium Thiosulfate
Titration Car-
tridge, 1 99N each
349-13 Starch Indicator 4-oz
Solution DB"
1073-99 Sulfamic Acid
Powder Pillows . 100
621-00 Bottle, glass-stop-
pered, BOD.
300 ml 4
966-00 Clippers, large . each
506-46 Cylinder graduaied
250 ml each
505-46 Flask. Erlenmeyer
250 ml each
2596-00 Glass Beads 100
Optional Apparatus
326-00 Clamp Holder
17205-00 Delivery Tube,
straight
17342-00 Delivery Tube,
90°
563-00 Support Stand
'luge vies avaiiaDie
Optional Larger Reagent Sizes
349-11 Starch Indicator
Solution
349-16
each
5
each
pi
qt
-50-
-------