Federal Water Pollution Control Administration
Division of Research
Analytical Quality Control Branch
FWPCA OFFICIAL INTERIM METHODS
For Chemical Analysis of Surface Waters
September 1968
-------
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Storet Parameter No. QQ435
Parameter : Acidity, Total (mg/1 as CaC03)
Method
• Volumetric, with electrometric endpoint.
Reference : l. Standard Methods for the Examination of Water and
Wastewater, 12th ed., APHA, Inc., N.Y., 1965,
46-47.
2. ASTM 1968 preprint, D1067, pp. 38-41.
Modifications: None
_ _ September 1968
Date: v
-------
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Storet Parameter No. 00410
Parameter : Alkalinity, Total (mg/1 as CaC03)
Method
: Volumetric, with electrometric endpoint.
Reference
1. Standard Methods for the Examination of Water and
Wastewater, 12th ed., APHA, Inc., N.Y., 1965,
48-52.
2. ASTM 1968 preprint, D1067, pp. 38-41.
Modifications: None
Date:
September 1968
-------
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Storet Parameter No. to be assigned
Parameter : Aluminum, Dissolved (yg/1)
Method
Reference
Filtration through 0.45 y membrane filter.
Measurement by atomic absorption.
Method is specific to the particular instrument.
General procedure is being selected.
Modifications: Use of 0>45 y membrane filter only.
Date: September 1968
-------
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Storet Parameter No. 01105
Parameter : Aluminum, Total Cyg/D
Method
Atomic absorption.
Reference : Method is specific to the particular instrument,
General procedure is being selected.
Modifications: None
Date; September 1968
-------
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Storet Parameter No. to be assigned
Parameter : Arsenic, Dissolved Cug/D
Method : Filtration through 0.45 y membrane filter.
Measurement by silver diethyldithiocarbamate
colorimetric method.
Reference : standard Methods for the Examination of Water and
Wastewater, 12th ed., APHA, Inc., N.Y., 1965,
56-57.
Modifications: Filtration through 0.45 p membrane filter only.
Date: September 1968
-------
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Storet Parameter No. QlOQQ
Parameter : Arsenic, Total, (yg/1)
Method
Measurement by silver diethyldithiocarbamate
colorimetric method.
Reference : Standard Methods for the Examination of Water and
Wastewater, 12th ed., APHA, Inc., N.Y., 1965,
56-57.
Modifications: None
Date: September 1968
-------
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Storet Parameter No. 00525
Parameter : Ash, Solids Dissolved (mg/1)
Method
Gravimetric, ignition at 600 C, modified.
Reference : Standard Methods for the Examination of Water and
Wastewater, 12th ed., APHA, Inc., N.Y., 1965,
247-248.
Modifications: Use of 0.45 y membrane filter only, for solids
separation.
Date; September 1968
-------
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Storet Parameter No. 00540
Parameter : Ash, Solids, Suspended (mg/1)
Method : Gravimetric, ignition at 600 C, modified.
Reference : Standard Methods for the Examination of Water and
Wastewater, 12th ed., APHA, Inc., N.Y., 1965,
247-248.
Modifications: use of 0.45 y membrane fLiter only for solids
separation.
Date; September 1968
-------
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Storet Parameter No. 00510
Parameter : Ash, Solids, Total (mg/1)
Method : Gravimetric, ignition at 600 C.
Reference : Standard Methods for the Examination of Water and
Wastewater, 12th ed., APHA, Inc., N.Y., 1965,
247-248.
Modifications: None
Date; September 1968
-------
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Storet Parameter No. 00310
Parameter : Biochemical Oxygen Demand, 5 day (mg/1)
Method
Non-official method - modified Winkler - azide method,
Reference : Standard Methods for the Examination of Water and Waste-
water, 12th ed., APHA, Inc., N.Y., 1965, 406-410; 415-421.
Modifications: 1. Full Bottle Technique
2. Scope and Application; For the BOD test to be most
meaningful the laboratory procedure should duplicate
environmental conditions -- temperature, mineral sub-
strate, water movement, biological population, etc. If
determination of the BOD in this manner was carried out
the procedure would be considered "standard"; however,
since it would be extremely difficult to reproduce these
conditions from one laboratory to another the test must
be recognized as a non-standard procedure, and there-
fore classified as "Non-Official".
3. Apparatus: Incubation bottles, 300 ml + 3 ml
capacity, with ground-glass stoppers.
4. Data Validity: The most valid BOD results are
obtained when samples have at least 2 mg/1 of depletion
Date; September 1968
-------
and at least 1 mg/1 of oxygen remaining. Values
that do not meet these criteria should be reported
with the Subscript L - meaning that either the
depletion or residual, were below the accepted
limits.
The minimum number of dilutions that should
be run on any sample is two - the preferable number
is three. In all cases the only figures that
should be used or averaged are those falling within
the desired or minimum ranges. If all resulting
values are below the minimum, then these data will
be averaged and reported with the proper connotation.
Example: 3 dilutions - 2 within limits.
1 below
Average, only those two falling
within limits.
3 dilutions - 1 within. 2 below
Report only the value falling
within the limits.
3 dilutions - 3 below
Average all three, report value
as BOD.
2 dilutions - 1 within. 1 below
Report only the value falling
within the limits.
2 dilutions - 2 within
Average both values.
5. Precision and Accuracy: The expected standard
deviation of the "Standard Methods" BOD procedure
is approximately + 20 percent of the mean value .
At present, data are not available to substantiate
whether or not the full bottle technique will alter
this reported deviation. However, it is felt that
since the FWPCA procedure does not significantly
alter the mechanics or chemistry of the Standard
Methods procedure, the precision and accuracy will
not be seriously affected.
Ballinger, D.G., Lishka, R.J., Reliability and
Precision of BOD and COD Determinations;
Journal WPCF, May 1962, pp 470-474. $[p 10-
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Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Storet Parameter No. _ta_hfi_assigned
Parameter : Cadmium, Dissolved (yg/1)
Method : Filtration through. 0.45 y membrane filter.
Measurement by atomic absorption.
Reference : Method is specific to the particular instrument.
General procedure is being selected.
Modifications: Use of 0.45 y membrane filter only.
Date: September 1968
-------
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Storet Parameter No. °1025
Parameter : Cadmium, Total Cyg/D
Method
: Atomic absorption.
Reference : Method is specific to the particular instrument.
General procedure is being selected.
Modifications: None
Date. September 1968
-------
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Storet Parameter No. to be assigned
Parameter : Calcium, Dissolved, as Ca, (mg/1)
Method : Filtration through 0.45 y membrane filter.
Measurement by atomic absorption.
Reference : Method is specific to the particular instrument.
General procedure is being selected.
Modifications: Use of 0.45 y membrane filter only.
Date: September 1968
-------
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Storet Parameter No. 00915
Parameter : Calcium, Total, as Ca, (mg/1)
Method
: Atomic absorption.
Reference
: Method is specific to the particular instrument.
General procedure is being selected.
Modifications: None
Date: September 1968
-------
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Storet Parameter No. QQ340
Parameter : Chemical Oxygen Demand, High Level (mg/1)
Official Interim Procedure #1
Method
: Volumetric, dichromate reflux.
Reference : 1. Standard Methods for the Examination of Water and
Wastewater, 12th ed., APHA, Inc., N.Y., 1965,
510-514.
2. ASTM Book of Standards, Part 23, 1967
D1252-67, pp. 244-247.
Modifications: None
Date: September 1968
-------
Reference
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Storet Parameter No. 00335
Parameter : Chemical Oxygen Demand, Low Level (mg/1)
Official Interim Procedure #2
Method : Volumetric, dichromate reflux, modified.
i. Standard Methods for the Examination of Water and
Wastewater, 12th ed. , APHA, Inc., N.Y., 1965,
510-514.
2. ASTM Book of Standards, Part 23, 1967
D1252-67, pp. 244-247.
Modifications: See new method write-up.
Date: SePtember 1968
-------
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHOD
for
Chemical Oxygen Demand - Low Level
Interim Official Procedure #2
1. Scope and Application;
This method is applicable when the chloride level is less than
100 mg/1 and the COD is in the range of 10-90 mg/1. Otherwise the
scope and application is exactly as the Interim Official Chemical
Oxygen Demand Procedure. Extreme care must be taken with this procedure
because a trace of organic matter from the glassware or atmospheric
contamination may cause a gross error. AH glassware used in the test
should be "aged" in that previous low level blank determinations must have
been run to eliminate traces of organic material.
2. Apparatus;
2.1) Reflux apparatus: 125 ml Erlenmeyer flasks with standard
ground glass 24/40 neck and 300 mm jacket Liebig, West, or equivalent
condensers with 24/40 ground glass joint, and a hot plate or mantle
with sufficient power to produce at least 9 watts/Sq. in. of heating
surface, or equivalent, to insure an adequate boiling of contents of
th£ refluxing flask.
3. Sampling; As per Official Interim Procedure #1.
4. Preservation; As per Official Interim Procedure #1.
5. Reagents;
5.1) Standard potassium dichromate solution: 0.025N. Dissolve
12.259 g K2Cr207, primary standard grade, previously dried at 103°C for
2 hours, in distilled water and dilute to 1000 ml. Mix this solution
SEP 1968
-------
-2-
thoroughly then dilute 100 ml to one liter with distilled water. See
referee procedure for elimination of nitrite interference.
5.2) Sulfuric acid reagent: Cone. H2S04 containing 23.5 g silver
sulfate, Ag2S04, per 9 Ib. bottle (1 to 2 days required for dissolution.)
5.3) Standard ferrous ammonium sulfate titrant: 0.025N
5.3.1) Dissolve 98 g of Fe(NH4)2 • 6H20 in distilled water.
Add 20 ml of cone. H2S04, cool, and dilute to 1000 ml. Dilute
100 ml of this solution to 1 liter with distilled water. This
solution must be standardized daily against K^Cr^Oy solution.
5.3.2) Standardization: To 15 ml of distilled water add 10 ml
of 0.025N Kr2Cr207 solution. Add 20 ml of H2S04 and cool.
Titrate with ferrous ammonium sulfate using 1 drop of ferroin
indicator. The color change is sharp, going from blue-green
to reddish-brown.
Normality = (ml K2Cr207) (0.025)
ml Fe (NH4)2(S04)2
5.4) Ferroin indicator solution: As per Official Procedure #1.
5.5) Silver Sulfate, reagent powder: As per Official Procedure #1.
5.6) Mercuric Sulfate: As per Official Procedure #1.
5.7) Sulfuric Acid: 36N, Reagent grade.
6. Procedure;
6.1) Determine chloride content of sample. Pipet 10 ml of sample
into the reflux flask. Add 10 ml of 0.025N Kr2Cr207 solution then 2 ml
of cone. H2SO^ and mix. Add HgSO^ in the ratio of 10 mg HgS04 to 1 mg
chloride, and swirl until all mercuric sulfate has dissolved. Add 2
glass beads which have previously been ignited at 600°C for 1 hour.
SEP 1968
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-3-
Then add 18 ml of sulfuric acid-silver sulfate solution and gently
swirl until the solution is thoroughly mixed.
6.2) Attach the flask to the condenser and reflux for 2 hours.
Cool and wash down the condenser with 3 ml of distilled water. Discon-
nect the condenser and wash the flask with 2 ml of water. Cool to room
temperature.
6.3) Titrate with standard ferrous ammonium sulfate using 1 drop
of ferroin indicator.
6.4) Run a blank using 10 ml of COD-free distilled water through
the entire procedure.
6.5) Concentration of dilute samples. If an increase in sensitivity
is required, it may be obtained by reducing a 20 ml sample volume by
boiling in the refluxing flask on a hot plate in the presence of all
reagents. A blank should be carried through the same procedure. This
technique has the advantage of concentrating without significant loss of
easily digested volatile materials. Hard to digest volatile materials,
such as volatile acids, are lost, but an improvement is gained over
ordinary evaporative concentration methods.
7. Calculation;
mg/1 COD = (a - b) c x 8000
ml sample
Where: a = ml FeCNH^^ (80^)2 used for blank;
b = ml Fe(NH,)2 (S0,)2 used for sample;
c = normality of Fe(NH ) (SO.) .
8. Precision and Accuracy:
Data are unavailable on the precision and accuracy of this method
at the present time.
SEP 1963
-------
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Storet Parameter No. to be assigned
Parameter : Chemical Oxygen Demand, Saline Waters (mg/1)
Official Interim Procedure #3
Method
: Volumetric, dichromate reflux, modified.
Reference : 1. Standard Methods for the Examination of Water and
Wastewater, 12th ed., APHA, Inc., N.Y., 1965,
510-514.
2. ASTM Book of Standards, Part 23, 1967
D1252-67, pp. 244-247.
Modifications: See new method write-up.
Date; September 1968
-------
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHOD
for
Chemical Oxygen Demand, Saline Waters (mg/1)
Official Interim Procedure #3.
1. Scope and Application;
When the chloride level exceeds 1000 mg/1 the minimum accepted
value for the COD will be 250 mg/1. COD levels which fall below this
value are highly questionable because of the high chloride correction
which must be made. Otherwise the scope and application is exactly as
the Interim Official Chemical Oxygen Demand Procedure #1.
2. Apparatus; As per Official Interim Procedure #l.
3. Sampling; As per Official Interim Procedure #1.
4. Preservation; As per Official Interim Procedure #1.
5. Reagents;
5.1) Standard potassium dichromate solution: As per Interim
Official Procedure #1.
5.2) Sulfuric acid reagent: Cone. t^SO^ containing 23.5 g silver
sulfate, Ag2SO/, per 9 Ib bottle (1 to 2 days required for dissolution).
5.3) Standard ferrous ammonium sulfate titrant, 0.25N:
5.3.1) Dissolve 98 g of Fe(NH4)2(S04)2 • 6H20 in distilled
water. Add 20 ml of cone. l^SO^, cool, and dilute to
1000 ml. This solution must be standardized against
the standard potassium dichromate solution daily.
SEP 1S68
-------
-2-
5.3.2) Standardization: Dilute 25.0 ml of standard
dichromate solution to about 250 ml with distilled
water. Add 75 ml cone, sulfuric acid. Cool then
titrate with ferrous ammonium sulfate titrant, using
10 drops of ferroin indicator.
Normality = (ml K2Cr20?)(0.25)
ml Fe(NH4)2(S04)2
5.4) Ferroin indicator solution: As per Official Interim Procedure #1,
•
5.5) Silver Sulfate, reagent powder: As per Official Interim
Procedure #1.
5.6) Mercuric Sulfate: As per Official Interim Procedure #1.
5.7) Sulfamic Acid: As per Official Interim Procedure #1.
5.8) Sulfuric Acid: 36N, reagent grade.
6. Procedure;
6.1) Pipet a 50 ml aliquot of sample not to exceed 800 mg/1 of COD
into a 500 ml, flat bottom, g.s. erlenmeyer. Add 25 ml of 0.25N Kr2Cr207
then 5.0 ml of cone. H2S04 (containing no silver sulfate). Add HgSOA in
the ratio of 10 mg to 1 mg chloride, based upon the mg of chloride in the
sample aliquot. Swirl until all the mercuric sulfate has dissolved.
Carefully add 70 ml of sulfuric acid-silver sulfate solution and gently
swirl until the solution is thoroughly mixed. Glass beads should be
added to the reflux mixture to prevent bumping, which can be severe and
dangerous. (CAUTION: The reflux mixture must be thoroughly mixed before
heat is applied. If this is not done, local heating occurs in the bottom
of the flask, and the mixture may be blown out of the condenser).
SEP ma
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-3-
6.2) Attach the flask to the condenser and reflux the mixture for
two hours.
6.3) Cool, and wash down the interior of the condenser with 25 ml
of distilled water. Break the joint of the condenser and wash the flask
and condenser joint with 25 ml of distilled water. Remove the condenser
and carefully add to the flask 175 ml of distilled water so that the
total volume is 350 ml. Cool to room temperature.
6.4) Titrate with standard ferrous ammonium sulfate using 10 drops
of ferroin indicator. (This amount must not vary from blank, sample and
standardization). The color change is sharp, going from blue-green to
reddish brown and should be taken as the end point although the blue-
green color may reappear within minutes.
6.5) Run a blank, using 50 ml of distilled water in place of the
sample together with all reagents and subsequent treatment.
6.6) For COD values greater than 800 mg/1 a smaller aliquot of
sample should be taken, however, the volume should be readjusted to
50 ml with distilled water having a chloride concentration equal to the
sample.
6.7) Chloride correction*- Prepare a standard curve of COD versus
mg/1 of chloride, using sodium chloride solutions of varying concentra-
tions following exactly the procedure outlined. The chloride interval,
as a minimum should be 4000 mg/1 up to 20,000 mg/1 chloride. Lesser
intervals or greater concentrations must be run as per the requirements
of the data, but in no case must extrapolation be allowed.
*Burns, E. R., Craig, M., Journal WPCF, Vol. 37, pp 1716-1721, 1967
SEP 1363
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-4-
7. Calculation;
mg/1 COD = (a - b) c x 8000 - d x 1.20
ml sample
where
COD = chemical oxygen demand from dichromate
a = ml Fe(NH^>2 (804)2 for blank;
b = ml FeCNH^^ (SO^^ for sample;
c = normality of Fe^H^^ (S0^)2;
d = chloride correction from curve (step 6.7)
1.20 = Compensation factor to account for the extent
of chloride oxidation which is dissimilar in
systems containing organic and nonorganic
material.
8. Precision and Accuracy;
Data are unavailable on the precision and accuracy of this method
at the present time.
SEP 1868
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Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Storet Parameter No. 00940
Parameter : Chloride (mg/1)
Method
: Volumetric, mercuric nitrate.
Reference : 1. Standard Methods for the Examination of Water and
Wastewater, 12th ed., APHA, Inc., N.Y., 1965,
87-90.
2. ASTM Book of Standards, Part 23, 1967
D512-67, pp. 25-27.
Modifications: None
Date; September 1968
-------
Parameter
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Storet Parameter No. 00365
: Chlorine Demand, 15 minutes (mg/1)
Method : No official method selected. Unofficial method
is for control of disinfection.
Reference : Standard Methods for the Examination of Water and
Wastewater, 12th ed., APHA, Inc., N.Y.,1965,
381-383.
Modifications: None
Date; September 1968
-------
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Storet Parameter No. 00370
Parameter : Chlorine Demand, 1 hour (mg/1)
Method : NO official method selected. Unofficial method
is for control of disinfection.
Reference : Standard Methods for the Examination of Water and
Wastewater, 12th ed., APHA, Inc., N.Y., 1965,
381-383.
Modifications: None
Date: September 1968
-------
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Storet Parameter No. QQ375
Parameter : chlorine Demand, 2 hour (mg/1)
Method : No officiai method selected. Unofficial method
is for control of disinfection.
Reference : standard Methods for the Examination of Water and
Wastewater, 12th. ed., APHA, Inc., N.Y., 1965,
381-383.
Modifications: uone
Date: September 1968
-------
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Storet Parameter No. QQ38Q
Parameter : chlorine Demand, 24 hour (mg/1)
Method
Reference
No official method selected. Unofficial method
is for control of disinfection.
Standard Methods for the Examination of Water and
Wastewater, 12th ed., APHA, Inc., N.Y., 1965,
381-383.
Modifications: None
Date; September 1968
-------
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Storet Parameter No. 50060
Parameter : Chlorine, Residual (mg/1)
Method : Volumetric, (iodometric)
Reference : Standard Methods for the Examination of Water and
Wastewater, 12th ed., APHA, Inc., N.Y., 1965,
376-378.
ASTM Book of Standards, Part 23 (1967), 249-252.
Modifications: None
Date. September 1968
-------
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Storet Parameter No. to be assigned
Parameter : Chromium, Dissolved (yg/1)
Method : Filtration through Q.45 y membrane filter.
Measurement by atomic absorption.
Reference : Method is specific to the particular instrument.
General procedure is being selected.
Modifications: Use of 0.45 y membrane filter only.
Date: September 1968
-------
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Storet Parameter No. Qifnn
Parameter : chromium, Total (yg/1)
Method : Atomlc absorption.
Reference : Method is specific to the particular instrument.
General procedure is being selected.
Modifications: None
Date: September 1968
-------
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Storet Parameter No. 00080
Parameter : Color (Pt - Co units)
Method
• Platinum—cobalt.
Reference : Standard Methods for the Examination of Water and
Wastewater, 12th ed., APHA, Inc., N.Y., 1965,
127-129.
Modifications:
Permanent color standards are acceptable if these are
individually and periodically recalibrated against
platinum cobalt standards.
See method comments attached.
Date; September 1968
-------
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHOD
for
Color
Method Selection
The Platinum-Cobalt Method is selected as the Interim Official
FWPCA Method. It is the simplest, most rapid, and is the most useful
under all conditions. The Tristimulus and Spectrophotometric Methods
are useful in detecting specific color problems.
Definitions
2. The term "color" in these methods is considered to be the color
of the light transmitted by the water or waste water after removing
the suspended material including the pseudocolloidal particles
("true color").
It is recognized that the color characteristics of water are
affected by reflectance ("apparent color"). However, until a suitable
method is available for making solution reflectance determinations,
the color measurement will be limited to the characteristics of light
transmitted by clarified samples.
The color of the filtered water is expressed in terms which
describe the sensation realized when viewing the clarified water.
The hue (red, yellow, green, etc.) of the color is designated by the
term dominant wave length, the degree of brightness by luminance,
and the saturation (pastel, pale, etc.) by purity.
SEP 1968
-------
2.
The light transmission data are converted to the color class-
ification terms by using standards adopted by the International
Commission on Illumination ("CIE"), and the selected-ordinate method.
Purity of Reagents
3. Reagent grade chemicals shall be used in all tests.
Sampling
4. Samples for the color determination should be representative
and must be taken in clean glassware. The color determination should
be made within a reasonable period, as biologic changes occurring in
storage may affect the color.
-------
3.
Platinum-Cobalt Method
Application
5. This method is applicable to the determination of color of
water and waste water for routine control purposes.
Principle of Method
6. Color is measured by visual comparison of the sample to
platinum-cobalt standards where one unit of color being that pro-
duced by 1 mg/1 platinum, in the form of the chloroplatinate ion.
Interference
7. Even a slight turbidity interfers with the test. The
recommended method for the removal of turbidity is by centrifugation.
The color is extremely pH dependent and invariably increases as
the pH of the sample is raised. The pH must be measured and recorded
along with the color.
Reagents
8. Same as given under "Preparation of Standards", pages 128 and
129, Standard Methods for the Examination of Water and Wastewater,
Twelfth Edition, 1965.
Procedure
9. Same as given on page 129, Standard Methods for the Examination
of Water and Wastewater. Twelfth Edition, 1965.
Calculation
10. Same as given on page 129, Standard Methods for the Examination
of Water and Wastewater. Twelfth Edition, 1965.
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Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Storet Parameter No. 00095
Parameter : Conductivity, Specific (micromhos/cm at 25 C)
Method : Instrumental, wheatstone bridge modified.
Reference : j. Standard Methods for the Examination of Water and
Wastewater, 12th ed., APHA, Inc., N.Y., 1965,
280-284.
2. ASTM Book of Standard, Part 23, 1967
D1125-64, pp. 179-184.
Modifications: Test conducted at standard temperature of 25 C only.
Date: September 1968
-------
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Storet Parameter No. to-he—assigned
Parameter : Copper, Dissolved
Method
Filtration through 0.45 y membrane filter.
Measurement by atomic absorption.
Reference
Method is specific to the particular instrument.
General procedure is being selected.
Modifications: Use of 0.45 y membrane filter only.
Date: September 1968
-------
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Storet Parameter No. 01040
Parameter : Copper, Total
Method
Atomic absorption.
Reference : Method is specific to the particular instrument.
General procedure is being selected.
Modifications: None
Date; September 1968
-------
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Parameter
Storet Parameter No. 00720
Cyanide (mg/1)
Method
Reference
Colorimetric or volumetric; distillation followed
by benzidine pyridine color development or silver
nitrate titration.
Standard Methods, 12th edition, 1965, 450-454.
Aldridge, W. N. 1944. Analyst (69) 262-265.
Nusbaum, I and P. Skupeko, 1951, Sewage and Ind.
Wastes, 231 (7), 875.
Modifications: Standard Methods, Page 450. Delete Section 1.1, para. 2.
Cyanogen bromide forms an addition product with
pyridine which in turn reacts with an aromatic
amine with rupture of the pyridine ring to form
an intensely colored dianilide of glutaconic
dialdehyde.
Benzidine is used as the aromatic amine producing
an orange to red colored compound with maximum
absorption at 480 my.
See Benzidine Pyridine method write-up attached.
Date; September 1968
-------
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHOD
for
Benzidine Pyridine Method Cyanide
Reagents
Purity of Reagents
Reagents shall be reagent grade and should conform to all speci-
fications of the Committee on Analytical Reagents, ACS. Other grades
of chemicals may be used if it has been determined that the reagent
is of sufficient quality to allow its use without reducing the precision
or accuracy of the method.
Purity of Water - Unless otherwise indicated, references to water
shall be understood to mean reagent water conforming to specifications
of reagent water (ASTM D1193).
(a) Phosphoric Acid (85%) Concentrated phosphoric acid.
(b) Phosphoric Acid Solution (1:9) Mix 1 volume of H3P04 (85%)
with 9 volumes of water.
(c) Methyl orange indicator (0.5g/liter). Dissolved 0.05 grams
of methyl orange in water and dilute to 100 ml.
(d) Bromine water (Saturated). To 250 ml of water add slightly
more liquid bromine than will dissolve on shaking. Store in a glass
stoppered actinic glass bottle.
SEP 1968
-------
(e) Sodium Arsenlte Solution - Dissolve 2 grains of Sodium
Arsenite Na2Ag03 in 100 ml of water.
(f) N-butyl alcohol reagent grade.
(g) Pyridine Solution - Combine 25 ml of pure pyridine with
2 ml of cone, hydrochloric acid, dilute to 100 ml with water.
(h) Benzidine Hydrochloride Solution - Dissolve 2 grams of
benzidine dihydrochloride in 100 ml of water and filter through
filter paper.
(i) Benzidine Pyridine mixture - Add 0.3 ml of benzidine solution
(h) to 5 ml of pyridine solution (g), mix and add immediately to sample.
Colorimetric Procedure
Take an aliquot or 20 ml of the absorption liquid obtained from the
distillation procedure. The aliquot should contain less than 0.5
micrograms of cyanide.
Place the aliquot in a test tube 25 x 150 or larger preferably
a screw cap culture tube; bring volume up to 20 ml with distilled. Add
2 drops of a methyl orange solution; shake and add dropwise a 10%
phosphoric acid solution until a red color develops. Add saturated
bromine water until definite bromine light yellow bromine color
develops. Discharge bromine color with dropwise addition of sodium
arsenite solution and add one drop in excess.
Add 10 ml of N-butyl alcohol.
Mix 0.3 ml of the benzidine reagent with 5 ml of pyridine solution;
add to sample and mix by vigorous shaking.
SEP 1968
-------
Allow 15 minutes for color to develop, decant carefully the
butyl alcohol phase and measure absorbance of the developed color with
photometer at 48Dm>i. Determine the concentration of the cyanide in the
sample by comparing with standards run simultaneously or when appropriate
number of points are plotted on calibration curve to permit calcula-
tion of slope which will not differ by one pat in a hundred. In all
cases at least three standards are to be run each day samples are
analyzed.
Colorimetric Procedure (for CN Concentration lower than Img per liter).
Calculate the cyanide concentration as follows:
r Y
CN-milligrams per liter = — ——: —r* ^r~r——
ml original sample x ml of aliquot used
C = micrograms of cyanide determined.
References;
Aldridge, W. N. "A New Method for Estimation of Micro Quantities of Cyanide
and the Cyanate,Analyst 69,262 (1944)
Nusbaum I and Skupeko Pe "Determination Cyanides in Sewage and Polluted
Waters "Sewage and Industrial Wastes 23, 7, 875 (July 1951)
American Society of Testing Materials, ASTM, Designation: DII93
SEP 1968
-------
Dissolved Oxygen
INTERIM OFFICIAL PROCEDURE
Azide Modification of lodometric Method
Full Bottle Technique
1. Scope and Application:
This method is applicable for use with most wastewaters and streams that
contain nitrite nitrogen and more than 1 mg/1 of ferrous iron. Other reducing
or oxidizing materials should be absent. If 1 ml fluoride solution is added
before acidifying the sample and there is no delay in titration, the method is
also applicable in the presence of 100-200 mg/1 ferric iron.
The azide modification is not applicable under the following conditions:
(a) samples containing sulfite, thiosulfate,polythionate, appreciable quantities
of free chlorine or hypochlorite (b) samples high in suspended solids (c) samples
containing organic substances which are readily oxidized in a highly alkaline
solution, or which are oxidized by free iodine in an acid solution (d) domestic
sewage (e) biological floes (f) where sample color interferes with endpoint de-
tection.
In instances where the azide modification is not applicable a DO probe will
be used.
2. Apparatus;
2.1) Sample Bottles - 300 ml +_ 3 ml capacity BOD incubation bottles with
tapered ground glass pointed stoppers and flared mouths.
2.2) Pipets - with elongated tips capable of delivering 2.0 ml _+ 0.1 ml
of reagent.
SEP 1968
-------
3. Sampling:
3.1) Where possible, collect the sample in a 300 ml BOD incubation bottle.
Special cautions are required to avoid entrainment or solution of atmospheric
oxygen or dissolution of dissolved oxygen.
3.2) Where samples are collected from shallow depths (less than 5 feet) use
of an APHA-type sampler is recommended. Use of a Kemmerer-type sampler is
recommended for samples collected from depths of greater than 5 feet.
3.3) When a Kemmerer is used, the BOD sample bottle should be filled to
overflowing. (Overflow for approximately 10 seconds). Outlet tube of Kemmerer
should be inserted to bottom of BOD bottle. Care must be taken to prevent tur-
bulence and the formation of bubbles when filling bottle.
3.4) The sample temperature should be recorded at time of sampling as pre-
cisely as required.
4. Preservation of Samples:
4.1) Do not delay the determination of dissolved oxygen in samples having
an appreciable iodine demand or containing ferrous iron. If samples must be
preserved either 4.1.1 or 4.1.2 below may be employed.
4.1.1) Add 2 ml of manganous sulfate reagent and then 2 ml of alkali
azide reagent to the sample contained in the BOD bottle. Both reagents must be
added well below the surface of the liquid. Stopper the bottle immediately and
mix the contents thoroughly. The sample should be stored at the temperature of
the collection water; or water sealed and kept at a temperature of 10 - 20°C, in
the dark.
4.1.2) Add 0.7 ml of concentrated ISO and 1 ml sodium azide solution
1953
-------
(2gNaN3 in 100 ml distilled water) to the sample in the DO bottle. Store
in sample as in method A. Complete the procedure using 2 ml of manganous
sulfate solution, 3 ml alkali iodide solution, and 2 ml of concentrated
H2S04.
4.2) If either preservation technique A or B is employed, complete
the analysis within 4-8 hours after sampling.
5. Reagents
5.1) Manganese sulfate reagent: As in Standard Methods
5.2) Alkaline-iodide-azide reagent: As in Standard Methods
5.3) Sulfuric acid, concentrated: As in Standard Methods
5.4) Starch solution: Prepare an emulsion of 10 g soluble starch in
a mortar or beaker with a small quantity of distilled water. Pour this emulsion
into 1 liter of boiling water, allow to boil a few minutes, and let settle
overnight. Use the clear supernate. This solution may be preserved by the
addition of 5 ml per liter of chloroform and storage in a 10°C refrigerator.
Dry, powdered starch indicators such as "thyodene" may be used in place of
starch solution.
5.5) Potassium Fluoride solution: Dissolve 40 g KF • 21^0 in distilled
water and dilute to 100 ml.
5.6) Sodium thiosulfate stock solution, 0.75N: Dissolve 186.15 g Na^S^Oo
5H20 in boiled and cooled distilled water and dilute to 1 liter. Preserve by
adding 5 ml chloroform.
5.7) Standard sodium thiosulfate titrant, 0.0375N: Prepare by diluting
50.0 ml of stock solution to 1 liter. Preserve by adding 5 ml of chloroform.
Standard sodium thiosulfate, exactly 0.0375N is equivalent to 0.300 mg of DO
per 100 ml. Standardize with 0.0375N potassium dichromate.
SEP 1963
-------
5.8) Standard potassium dichromate, 0.0375N: Dissolve 1.839 potassium
dichromate, previously dried 2 hours at 103°C, in 1 liter of distilled water.
The solution must be prepared in a volumetric flask.
5.9) Standardization of 0.0375N sodium thiosulfate: Dissolve 2 g +
0.1 g KI in 100 to 150 ml distilled watery add 10 ml of 10% H2S04 followed
by 20 ml standard potassium dichromate. Place in dark for 5 minutes, dilute
to 400 ml and titrate with the standard sodium thiosulfate titrant to a pale
straw color. Add 1-2 ml starch solution and continue the titration drop by
drop until the blue color disappears. Run in duplicate. Duplicate deter-
mination should agree within 0.05 ml.
6 . Procedure :
6.1) To the sample collected in the BOD incubation bottle add 2 ml of
the manganous sulfate solution followed by 2 ml of the alkali-iodide-azide
reagent, well below the surface of the liquid; stopper with care to exclude
air bubbles and mix well by inverting the bottle several times. When the
precipitate settles, leaving a clear supernatant above the manganese hydroxide
floe, shake again. With estuarine-type waters, a minimum 2 minute period of
contact with the precipitate rather than settling is sufficient. When
settling has produced at least 100 ml of clear supernate, carefully remove
the stopper and immediately add 2.0 ml of cone. l^SO^ (sulfamic acid packets,
2
3 gm, may be substituted for l^SO^ ) by allowing the acid to run down the
The volume of standard dichromate to be employed in the standardization
procedure may be reduced to 9 ml to accomodate the use of a 10 ml burette.
o
Kroner, R.C., Longbottom, J.E., Gorman, R. , A Comparison of Various Reagents
Proposed for Use in the Winkler Procedure for Dissolved Oxygen, PHS Water
Pollution Surveillance System Applications and Development Report #12, Water
Quality Section, Basic Data Branch, July, 1964.
-------
neck of the bottle, re-stopper, and mix by gentle inversion until the iodine
is uniformly distributed throughout the bottle. Complete the analysis within
45 minutes.
6.2) Transfer the entire bottle contents by inversion into a 500 ml
wide mouth erlenmeyer and titrate with 0.0375N thiosulfate solution (where
2
problems of stability arise, 0.0375N PAO may be substituted as titrant ) to
a pale straw color. Add 1-2 ml of starch solution or 0.1 g of powdered
indicator and continue to titrate to the first disappearance of the blue
color.
6.3) If ferric iron is present (100 to 200 ppm), add 1.0 ml of KF
solution before acidification.
6.4) Occasionally a dark brown or black precipitate persists in the
bottle after acidification. This precipitate will dissolve if the solution
is kept for a few minutes longer than usual or, if particularly persistant,
a few more drops of l^SO^ will effect dissolution.
7. Calculation:
7.1) Each ml of 0.0375 sodium thiosulfate titrant is equivalent to 1 mg/1
DO when the entire bottle contents are titrated.
7.2) If the results are desired in milliliters of oxygen gas per liter
at 0°C and 760 mm pressure, multiply mg/1 DO by 0.698.
7.3) To express the results as percent saturation at 760 mm atmospheric
pressure, the solubility data in Table 25 (Whipple & Whipple Table, Page 409
Standard Methods, 12th Edition) may be used. Equations for correcting the
solubilities to barometric pressures other than mean sea level are given
below the Table.
2
Kroner, R.C., Longbottom, J.E., Gorman R., A Comparison of Various Reagents
Proposed for Use in the Winkler Procedure for Dissolved Oxygen, PHS Water
Pollution Surveillance System Applications and Development Report #12, Water
Quality Section, Basic Data Branch, July 1964. (
•
-------
7.4) The solubility of DO in distilled water at any barometric
pressure, P (mm Hg), temperature, T°C, and saturated vapor pressure,
u (mm Hg), for the given T, may be calculated between the temperature of
0° and 30°C by:
ml/1 DO = (P - U) x 0.678
35 +T
and between 30° and 50°C by:
ml/1 DO = (P - U) x 0.827
49 +T
8. Precision and Accuracy:
Exact data are unavailable on the precision and accuracy of this
technique however, reproducibility is approximately 0.2 ppm of DO at the
7.5 ppm level due to equipment tolerances and uncompensated displacement
errors.
SCP
-------
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Storet Parameter No. 00950
Parameter : Fluoride (mg/1)
Method
: Colorimetric, SPADNS, with distillation.
Reference
Standard Methods for the Examination of Water
and Wastewater, 12th ed., APHA, Inc., N.Y., 1965,
144-146.
ASTM Book of Standards, Part 23, 1967
1968 preprint, D1179.
Modifications: None
Date; September 1968
-------
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Storet Parameter No. 00950
Parameter : Fluoride (mg/1)
Method
: Colorimetric, SPADNS, with distillation.
Reference
Standard Methods for the Examination of Water
and Wastewater, 12th ed., APHA, Inc., N.Y., 1965,
144-146.
ASTM Book of Standards, Part 23, 1967
1968 preprint, D1179.
Modifications: None
Date; September 1968
-------
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Storet Parameter No. 00910
Parameter : Hardness, Calcium (mg/1
Method : Volumetric, with EDTA
Reference : ASTM Book of Standards, Part 23, 1967
D1126-67, pp. 188-191.
Modifications: None
Date; September 1968
-------
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Storet Parameter No. nnQ20
Parameter : Hardness, Magnesium (mg/1
Method
Volumetric, with EDTA, by difference.
Reference
ASTM Book of Standards, Part 23, 1967
D1126-67, pp. 188-191.
Modifications: None
Date: September 1968
-------
Parameter
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Storet Parameter No. 00900
: Hardness, Total (mg/1 CaC03)
Method
: Volumetric, with EDTA.
Reference : ASTM Book of Standards, Part 23, 1967
D1126-67, pp. 188-191.
Modifications: None
Date; September 1968
-------
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Storet Parameter No. to be assigned
Parameter : Iron, Dissolved
Method : Filtration through 0.45 y membrane filter.
Measurement by atomic absorption.
Reference : Method is specific to the particular instrument.
General procedure is being selected.
Modifications: Use of 0.45 y membrane filter only.
Date; September 1968
-------
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Storet Parameter No. 0.1045
Parameter : Iron, Total
Method
Atomic Absorption
Reference : Method is specific to the particular instrument,
General procedure is being selected.
Modifications: None
September 1968
-------
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Storet Parameter No. to be assigned
Parameter : Lead, Dissolved
Method : Filtration through. 0.45 y membrane filter.
Measurement by atomic absorption.
Reference : Method is specific to the particular instrument.
General procedure is being selected.
Modifications: Use of 0.45 y membrane filter only.
Date: September 1968
-------
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Storet Parameter No. 01049
Parameter : Lead, Total
Method
Atomic absorption.
Reference : Method is specific to the particular instrument.
General procedure is being selected.
Modifications: None
Date; September 1968
-------
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Storet Parameter No. to be assigned
Parameter : Magnesium, Dissolved
Method : Filtration through 0.45 y membrane filter.
Measurement by atomic absorption.
Reference : Method is specific to the particular instrument.
General procedure is being selected.
Modifications: Use of 0.45 y membrane filter only.
Date t
-------
Federal Water Pollution Control Administration
Analytical Quality Control' Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Storet Parameter No. 00925
Parameter : Magnesium, Total
Method
: Atomic absorption.
Reference : Method is specific to the particular instrument.
General procedure is being selected.
Modifications: None
Date; September 1968
-------
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Storet Parameter No. to be assigned
Parameter : Manganese, Dissolved
Method : Filtration through 0.45 y membrane filter.
Measurement by atomic absorption.
Reference : Method is specific to the particular instrument.
General procedure is being selected.
Modifications: Use of 0.45 y membrane filter only.
Date: September 1968
-------
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Storet Parameter No. 01055
Parameter : Manganese, Total
Method
: Atomic absorption.
Reference : Method is specific to the particular instrument.
General procedure is being selected.
Modifications: None
Date: SePtember 1968
-------
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Storet Parameter No. 38260
Parameter : MBAS (Methylene Blue Active Substance) (mg/1)
Method
Methylene Blue Method.
Reference : Standard Methods for the Examination of Water and
Wastewater, 12th ed., APHA, Inc., N.Y., 1965,
297-299.
Modifications: None
Date; September 19.68
-------
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Storet Parameter No. 00610
Parameter : Nitrogen, Ammonia (mg/1)
Method : Manual - Distillation.
Automated - In preparation.
Reference : i. Standard Methods for the Examination of Water and
Wastewater, 12th ed., APHA, Inc., N.Y., 1965,
187-193.
2. ASTM Book of Standards, Part 23, 1967
D1426-58, pp. 336-338.
Modifications: New method write-ups. See attached.
Date: September 1968
-------
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHOD
for
Nitrogen-Ammonia by Distillation
1. Scope
1.1 This distillation method covers the determination of ammonia-
nitrogen exclusive of total Kjeldahl nitrogen in surface waters (both
fresh and saline) and industrial waste water.
2. Purity of Reagents
2.1 Reagent grade chemicals shall be used in all tests. Unless
otherwise indicated, it is intended that all reagents shall conform
to the specifications of the Committee on Analytical Reagents of the
American Chemical Society, where such specifications are available.
Other grades of reagents may be used, provided it is first ascertained
that the reagent is of sufficiently high purity to permit its use
without reducing the accuracy of the determination.
2.2 All reagents and standards are to be prepared with ammonia—free
water. Such water is best prepared by the passage of distilled water through
an ion-exchange column containing a strongly acidic cation-exchange resin
mixed with a strongly basic anion-exchange resin. These resins should
also be selected so that organic compounds which might subsequently
interfere with the ammonia determination will be removed.
196?
-------
2.
3. Sample Preservation
3.1 Until more conclusive data are obtained samples may be
preserved by the addition of 1.0 ml concentrated I^SO^ or 40 mg Hg"1"1"
per liter. If possible, the samples should be kept in a frozen state
until analyzed.
DISTILLATION METHOD
4. Application
4.1 This method is applicable to all types of water and is
the method of choice where economics and sample load do not warrant
the use of automated equipment.
5. Summary of Method
5.1 The sample is buffered at a pH of 9.5 wi±h a borate buffer
in order to decrease hydrolysis of cyanates and organic nitrogen
compounds, and is then distilled into a solution of boric acid. The
ammonia in the distillate can be determined either colorimetrically
by nesslerization or titrimetrically with standard sulfuric acid with
the use of a mixed indicator, the choice between these two procedures
depending on the concentration of the ammonia. In the analysis of sea
water the calcium and magnesium salts remain in solution as their
soluble borates.
6. " Interferences
6.1 A number of aromatic and aliphatic amines, as well as other
compounds, both organic and inorganic, will cause turbidity upon the
addition of Nessler reagent, so direct nesslerization has been discarded
SEP
1968
-------
3.
as an official method. Cyanate, which may be encountered in certain
industrial effluents, will hydrolyze to some extent even at the pH
of 9.5 at which distillation is carried out. Volatile alkaline
compounds such as hydrazine will influence the titrimetric results.
Some volatile compounds, such as certain ketones, aldehydes, and
alcohols, may cause an off-color upon nesslerization in the dis-
tillation method. Some of these, such as formaldehyde, may be
eliminated by boiling off at a low pH prior to distillation and
nesslerization. Residual chlorine must also be removed by pre-
treatment of the sample with sodium thiosulfate before distillation.
7. Apparatus
7.1 An all-glass distilling apparatus with an 800-1000 ml
flask.
7.2 Spectrophotometer or filter photometer for use at 425 my
and providing a light path of 1 cm or more.
7.3 Nessler tubes: Matched Nessler tubes (APHA Standard)
about 300 mm long, 17 mm inside diameter, and marked at 225 mm +_
1.5 mm inside measurement from bottom.
7.4 Erlenmeyer flasks: The distillate is collected in 500 ml
glass-stoppered flasks. These flasks should be marked at the 350 and
the 500 ml volumes. With such marking, it is not necessary to
transfer the distillate to volumetric flasks.
SEP 1968
-------
4.
8. Reagents
8.1 Ammonium chloride, standard solution. - (1 ml =
0.01 mg NH3-N). - Dissolve 3.819 g NH^Cl in water and bring
to volume in a 1 liter volumetric flask for use as a stock solution.
Dilute 10 ml of this stock solution to 1 liter in a volumetric flask
for use as the standard ammonium chloride solution.
8.2 Boric acid solution (20 g/1). - Dissolve 20 g H3B03 in
water and dilute to 1 liter.
8.3 Mixed indicator. - Mix 2 volumes of 0.2 percent methyl
red in 95 percent ethyl alcohol with 1 volume of 0.2 percent methylene
blue in 95 percent ethyl alcohol. This solution should be prepared
fresh every 30 days.
Note 1. — Specially denatured ethyl alcohol conforming to
Formula 3A or 30 of the U.S. Bureau of Internal Revenue may
be substituted for 95 percent ethanol.
8.4 Nessler reagent. - Dissolve 100 g of mercuric iodide and
70 g of potassium iodide in a small amount of water. Add this mixture
slowly, with stirring, to a cooled solution of 160 g of NaOH in 500 ml
of water. Dilute the mixture to 1 liter. If this reagent is stored
in a Pyrex bottle out of direct sunlight, it will remain stable for a
period of up to 1 year.
Note 2. — This reagent should give the characteristic color
with ammonia within 10 minutes after addition, and should not
produce a precipitate with small amounts of ammonia (0.04 mg in
a 50 ml volume).
8.5 Borate buffer. - Add 88 ml. of 0.1 N NaOH solution to 500 ml
of 0.025 M sodium tetraborate solution (.5.0 g Na^B^O^ per liter) and
dilute to 1 liter.
SEP
-------
5.
8.6 Sulfuric acid, standard solution (0.02 N, 1 ml =
0.28 mg NH3~N). - Prepare a stock solution of approximately 0.1 N acid
by diluting 3 ml of concentrated 1^504 ^SP 8r I-8*) to 1 liter with
C02~free distilled water. Dilute 200 ml of this solution to 1 liter
with C02-free distilled water. Standardize the approximately 0.02 N
acid so prepared againstO.0200 N Na2C03 solution. This last solution
is prepared by dissolving 1.060 g anhydrous Na2CC>3, oven-dried at 140° C,
and diluting to 1 liter with (X^-free distilled water.
Note 3. — An alternate and perhaps preferable method is to
standardize the approximately 0.1 N l^SO^ solution against a
0.100 N Na2C03 solution. By proper dilution the 0.0200 N acid
can then be prepared.
8.7 Sodium hydroxide (IN). - Dissolve 40 g NaOH in ammonia-free
water and dilute to 1 liter.
8.8 Dechlorinating reagents. - A number of dechlorinating reagents
may be used to remove residual chlorine prior to distillation. These
include:
(a) Sodium thiosulfate (1/70 N): Dissolve 3.5 g Na2S203 in
ammonia-free water and dilute to 1 liter. One ml of this solution
will remove 1 mg/1 of residual chlorine in 500 ml of sample.
(b) Sodium arsenite (1/70 N): Dissolve 1.0 g NaAs02 in ammonia-
free water and dilute to 1 liter.
9. Procedure
9.1 Preparation of equipment. — Add 500 ml of ammonia-free
water to an 800 ml Kjeldahl flask. The addition of boiling chips
which have been previously treated with dilute NaOH will prevent
bumping. Steam out the distillation apparatus until the distillate
shows no trace of ammonia with Nessler reagent.
SEP 1968
-------
5.
9.2 Sample preparation. - To 400 ml of sample add 1.0 N NaOH
until the pH is 9.5, checking the pH during addition with a pH meter.
9.3 Distillation. - Transfer the sample, the pH of which has been
adjusted to 9.5, to an 800 ml Kjeldahl flask and add 25 ml of the
borate buffer. Distill 300 ml at the rate of 6-10 ml/min. into 50 ml
of 2% boric acid contained in a 500 ml glass stoppered Erlenmeyer flask.
Dilute the distillate to 500 ml in the flask and nesslerize an aliquot
to obtain an approximate value of the ammonia—nitrogen concentration. For
concentrations above 1.0 mg/1 the ammonia should be determined titri-
metrically. For concentrations below this value it is determined
colorimetrically.
9.4 Determination of ammonia in distillate. - Determine the ammonia
content of the distillate either titrimetrically or colorimetrically
as described below. (See 9.4.1 and 9.4.2).
9.4.1 Titrimetric determination. — Add 3 drops of the mixed
indicator to the distillate and titrate the ammonia with the 0.02 N
H2s<-*4» notching the end point against a blank containing the same
volume of ammonia-free water and 113603 solution.
9.4.2 Colorimetric determination. — Prepare a series of 14
Nessler tubes containing the following volumes of the standard solution:
Q.0,,0.2, 0.4, 0.6, 0.8, 1.0, 1.2, 1.4, 1.7, 2.0, 2.5, 3.0, 3.5, and 4.0
ml. Dilute each tube to 50 ml. with ammonia-free water. Add 1 ml of
Nessler reagent and mix. After 20 minutes read the optical densities at
425 my against a compensating blank of nesslerized ammonia—free water.
From the values obtained prepare a standard curve.
SEP
-------
6.
Determine the ammonia in the distillate by nesslerizing 50 ml
or an aliquot diluted to 50 ml and reading the optical density at
425 my as described above for the Standards. Ammonia-nitrogen content
is read from the standard curve.
10.Calculations
(Tentative until a Standard Method for calculating results is
adopted).
10.1 Titrimetric
/i x™ XT A x 0.28 x 1000
mg/1 NH3-N =
in which:
A = ml 0.02 N H2S04 used
S = ml sample
10.2 Spectrophotometric
II XTU XT A X 1000
mg/1 NH3-N = Q>8 s
in which:
A = mg NHo^ read from standard curve
S = volume of distillate nesslerized
11. Precision
11.1 Precision and accuracy data are not available at this time.
SEP 1968
-------
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Storet Parameter No. QQ625
Parameter : Nitrogen, Kjeldahl, Total (mg/1)
Method
Reference
Acid digestion and distillation, with titration
or nesslerization, modified.
Standard Methods for the Examination of Water and
Wastewater, 12th ed., APHA, Inc., N.Y., 1965,
403-404.
Modifications: See method write-up.
Date: September 1968
-------
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHOD
Hitrogen-Kjeldahl Total
Scope
1. This method covers the determination of total Kjeldahl
nitrogen in fresh and estuarine waters. Two alternatives
are listed for the determination of ammonia after distillation
in the official method. The Kjeldahl procedure converts the
nitrogen of most components of biological origin, such as
amino acids, peptides and proteins, but may not convert the
nitrogeneous matter in many industrial wastes, such as
azines, hydrazones, nitro compounds, oximes, semi carbazones,
and some refractory tertiary amines. The titrimetric method
is applicable to concentrations above 2 mg N per liter and
possibly to lower concentrations if reagent blanks are con-
sistent enough. The nesslerization method is applicable to
concentrations above 0.1 mg N per liter. The lower limit
can be extended by concentration of the distillate prior to
nesslerization. While the official method is outlined for a
macro system, the same chemistry applied in a micro system
(Standard Methods for the Examination of Water and Waste-
water, llth Edition, pg 305) is considered to be the same as
the official method.
Definitions
?. (a) Total Kjeldahl nitrogen is defined as the sum of free
ammonia and of organic nitrogen compounds which are converted
to (NH^^SO^ under the conditions of digestion which are
specified below.
(b) Organic Kjeldahl nitrogen is defined as the differ-
ence obtained by subtracting the free ammonia value (reference
to be cited) from the total Kjeldahl nitrogen value. This may
be determined directly by removal of ammonia before digestion.
(c) Organic nitrogen is defined as the nitrogen derived
from all organic substances in the sample and shall include
Kjeldahl nitrogen.
SEP 1963
-------
2.1
Purity of Reagents
3. (a) Reagent grade chemicals shall be used in all tests.
Unless otherwise indicated, it is intended that all reagents
shall conform to the specifications of the committee on
Analytical Reagents of the American Chemical Society, where
such specifications are available. Other reagents may be
used, provided it is first ascertained that the reagent is
of sufficiently high purity to permit its use without
lessening the accuracy of the determination. Sulfuric acid,
in particular, is subject to absorption of ammonia and should
be protected from possible ammonia contamination.
(b) vJater shall be understood to mean distilled water
which is free of ammonia. Such water is best prepared by
the passage of distilled water through an ion-exchange column
containing a strongly acidic cation-exchange resin mixed with
a strongly basic anion-exchange resin. These resins should
be selected so that organic compounds which might subsequently
interfere with the determination will be removed. (Note 1)
Note 1: The regeneration of the ion-exchange column
should be carried out according to the
instruction of the manufacturer.
4. Sampling and Preservation
(a) Collect the samples in accordance with the appli-
cable methods recommended by the Committee on
Sampling.
(b) The samples can be preserved for analysis at ice
temperature for a period not exceeding 48 hours.
Samples can be preserved with 1 ml cone. H^SO^
per liter of sample and retained for longer periods
provided that the relationship between organic
nitrogen and ammonia is not of interest. The
H^SO^ will retain ammonia in solution; however,
it accelerates the conversion of organic nitrogen
to ammonia. Samples treated with H^SO^ are also
subject to gain ammonia from the air if not
tightly sealed.
SEP 1963
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2.2
Digestion Method
Application
5. This method is applicable to all types of fresh and
estuarine waters, containing from 0 to 100 mg N per liter.
Summary of Method
6. The sample is heated in the presence of concentrated
sulfuric acid, K^SO^ and HgO and evaporated until SO^ fumes
are obtained and the solution becomes colorless or pale
yellow. The residue is cooled, diluted and is treated and
made alkaline with a hydroxide-thiosulfate solution. The
ammonia is distilled and determined after distillation either
by nesslerization (see appropriate references) or titrimet-
rically.
Apparatus
7. (a) Digestion Apparatus
Kjeldahl digestion apparatus with 800 ml flasks and suction
takeoff to remove water and S0~ fumes.
(b) Distillation Apparatus
The Kjeldahl flask is connected to a condenser and the
adaptor is so arranged that the distillate can be collected
for nesslerization or in indicating H-jBO-j solution for titration.
(c) Colorimeter of Nessler tubes as required for nessler-
ization (see ammonia nitrogen).
Reagents
8. (a) Mercuric Sulfate Solution
Dissolve 8 g red mercuric oxide, HgO, in 50 ml 1:5
H90-H7S04 solution and dilute to 100 ml with H?0.
SEP 1S68
-------
(b) Sulfuric Acid - Mercuric Sulfate - Potassium
Sulfate Solution
Dissolve 267g ^SO* in 1,300 ml water and add 400 ml
concentrated VSO. Add 50 ml mercuric sulfate solution and
dilute to 9. liters.
(c) Sodium Hydroxide - Sodium Thiosulfate Solution
Dissolve 500g HaOH and 25g Na2S203 5H20 in water and
dilute to 1 liter.
(d) Phenolphthalein Indicator Solution
Dissolve 5g phenolphthalein in 500 ml 95% ethyl alcohol
or isopropanol and add 500 ml water. Add 0.02 NaOH dropwise
until a faint pink color appears.
(e) Mixed Indicator
Mix 2 volumes of 0.270 methyl red in 95% ethanol with 1
volume of 0.270 methylene blue in ethanol. Prepare fresh every
30 days.
(f) Boric Acid Solution
Dissolve 20g boric acid, H^BO^, in water and dilute to
1 liter with water.
(g) Sulfuric Acid Titrant, 0.020N.
In this strength 1.00 ml = 0.28 mg N.
Procedure
9. (a) Preparation of Apparatus
The distillation apparatus should be presteamed before
use by distilling a 1:1 mixture of ammonia-free water and
sodium hydroxide -sodium thiosulfate solution until the
distillate is ammonia free. This operation should be
repeated each time the apparatus is out of service long
enough to accumulate ammonia (usually 4 hours or more).
(b) Digestion
Place a measured sample or the residue from the distil-
lation in the ammonia determination (for Organic Kjeldahl only)
into an 800 ml Kjeldahl flask. The sample size can be deter-
mined from the follox^ing table:
SEP 1958
-------
0 -
5 -
10 -
20 -
50 -
5
10
20
50
100
Kjeldahl Nitrogen Sample Size
in sample, mg/1 ml
500
250
100
50.0
25.0
Dilute the sample, if required, to 500 ml, and add 100 ml
sulfuric acid - mercuric sulfate - potassium sulfate solution
(Note 2), and evaporate the mixture in the Kjeldahl apparatus
until 363 fumes are given off and the solution turns colorless
or pale yellow. Cool the residue and add 300 ml water.
Note 2: Alternately digest the sample with 1 Kel-Pac
(Olin-Matheson) and 20 ml l^SO^.
(c) Distillation
Make the digestate solution alkaline by carefully adding
sodium hydroxide - thiosulfate solution without mixing. Connect
a condenser to the Kjeldahl flask and connect the apparatus
in such a manner that the tip of the condenser extends well
below the level of 100 ml of boric acid. Mix and distill
until 200 ml of distillate is collected. Add 1 ml of mixed
indicator and titrate with 0.0200N H^SC^ to a pale lavender
endpoint. Run a blank on the reagents and correct as required.
Calculation
10. (a) Calculate total Kjeldahl nitrogen, in milligrams per
liter, in the original sample as follows:
total Kjeldahl nitrogen, mg/1 - (A-B) x N x F x 1000
S
or A-B x 280
where:
A = milliliters of standard 0.020N H?SO, solution used
in titrating sample
B = milliliters of standard 0.020N H?SO, solution used
in titrating blank
N = normality of sulfuric acid solution
SEP
1963
-------
F = millequivalent weight of nitrogen (14 mg)
3 = milliliters of sample digested
(b) If nesslerization is used, follow ammonia
procedure calculations.
(c) Calculated organic Kjeldahl nitrogen, in
milligrams per liter, as follows:
organic Kjeldahl nitrogen, mg/1 - C - D
whe re:
C = total Kjeldahl nitrogen in mg/1
D = ammonia nitrogen, in mg/1
Precision and Accuracy
11. The precision and accuracy will be established by
FWPCA laboratories.
SEP 1963
-------
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Storet Parameter No. 00620
: Nitrogen, Nitrate (ing/1)
Manual Method: Brucine Sulfate, colorimetric for fresh
: and salt water.
Automated Method A: reduction, colorimetric for fresh water.
Automated Method B: Brucine Sulfate, colorimetric for
saline water. Cto be added at later date)
1. Standard Methods for the Examination of Water and
Wastewater, 12th ed., APHA, Inc., N.Y., 1965,
198-200.
2. ASTM Book of Standards, Part 23, 1967,
D992-52, pp. 138-140.
Modifications: New method write-ups. See attached.
Parameter
Method
Reference
Date: September 1968
-------
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHOD
for
Nitrogen-Nitrate
1. Scope
1.1 The following methods are suitable for the determination
of nitrogen-nitrate in water samples:
a. Manual - Brucine Sulfate (fresh and salt water)
b. Automated A, Hydrazine Reduction (fresh water)
c. Automated B, Brucine Sulfate (saline water).
(.to be added at later date)
2. Purity of Reagents
2.1 Reagent grade chemicals shall be used in all tests. Unless
otherwise indicated, it is intended that all reagents shall conform
to the specifications of the Committee on Analytical Reagents of the
American Chemical Society where such specifications are available.
Other grades of reagents may be used, provided it is first ascertained
that the reagent is of sufficiently high purity to permit its use
without reducing the accuracy of the determination. Distilled water
free of nitrite and nitrate is to be used in preparation of all reagents
and standards.
3. Sample Preservation
3.1 Until more conclusive data is obtained, samples may be
preserved as follows:
(a) Addition of 40 mg Hg/1 (as HgC^) and stored at 4° C.
(b) Addition of 1 ml of CHC13/100 ml sample. Store at 4° C.
SEP 1968
-------
2.
(c) Freezing.
Note 1. — Data available at the present time indicate
that in using the above methods the nitrate concentration
is stable over a period of at least six weeks.
MANUAL METHOD
4. Application and Principle of Method
4.1 This method is applicable to a wider variety of samples than
either of the two automated methods, because modification can be made
to remove or correct for turbidity, color, salinity, or dissolved
organic compounds in the samples.
4.2 The principle of the method is based upon the reaction of the
nitrate ion with brucine sulfate in a 13 N t^SO^ solution at about 100° C.
The optical density of the resulting colored complex is measured at
410 my.
4.3 Applicable range is 0.1 to 2 mg N-NO-/1.
5. Interferences
5.1 Dissolved organic matter will cause an off color in 13 N
H^SO^ and must be compensated for by additions of all reagents except
the brucine-sulf anilic acid reagent. This also applies to natural
color present not due to dissolved organics.
5.2 If turbidity is present, it must be removed by prior filtration,
preferably through a 0.45 y membrane filter.
5.3 The effect of salinity is eliminated by addition of sodium
chloride to the blanks, standards and samples.
5.4 All strong oxidizing or reducing agents interfere. The presence
of oxidizing agents may be determined by the addition of orthotolidine
reagent.
-------
3.
5.5 Residual chlorine interference is eliminated by the
addition of sodium arsenite.
5.6 Ferrous and Ferric iron and quadrivalent manganese give
slight positive interference, but in concentrations less than 1 mg/1
these are negligible.
6. Apparatus
6.1 Spectrophotometer or filter photometer suitable for measuring
optical densities at 410 my and capable of accommodating 25 mm diameter
cells.
6.2 Sufficient number of 25 mm diameter matched tubes for
reagent blanks, standards, and samples.
6.3 Neoprene coated wire racks to hold 25 mm diameter tubes.
6.4 Water bath suitable for use at 100° C. This bath should
contain a stirring mechanism so that all tubes are at same temperature.
6.5 Water bath suitable for use at 10-15°C.
7. Reagents
7.1 Sodium Chloride Solution (300 g/1). - Dissolve 300 g NaCl
in distilled water and dilute to 1000 ml.
7.2 Sulfuric Acid Solution. - Carefully add 500 ml H2S04 (SP 8r 1-84)
to 125 ml distilled water. Cool and keep tightly stoppered to prevent
absorption of atmospheric moisture.
7.3 Brucine-Sulfanilic Acid Reagent. - Dissolve 1 g brucine
sulfate I(C23 H26 N^^-l^SCy 7 H20] and 0.1 g sulfanilic acid
(NH2 C6 H4 S03H . H20) in 70 ml hot distilled water. Add 3 ml concentrated
HC1, cool, mix and dilute to 100 ml. Store in a dark bottle at 5° C.
SEP 1968
-------
4.
This solution is stable for several months; the pink color that develops
slowly does not effect its usefulness. Mark bottle with warning;
CAUTION; Brucine jSulfate is toxic; take care to avoid ingestion.
7.4 Stock Potassium Nitrate Solution (1 ml = 0.1 mg N03~N)
Dissolve 0.7218 g anhydrous KNO, in distilled water and dilute to 1 liter,
7.5 Standard Potassium Nitrate Solution (1ml = 0.01 mg
N03-N). - Dilute 100 ml of the stock solution to 1 liter. This standard
solution should be prepared fresh weekly.
7.6 Acetic Acid (1+3) - Dilute 1 voL glacial CH COOH with
3 vol. distilled water.
8. Procedure
8.1 Adjust the pH of the samples to approximately pH 7 with
1+3 acetic acid and if necessary filter through a 0.45 y membrane
filter or Whatman No. 42 filter paper depending on the amount and
type of suspended solids present.
8.2 Set up the required number of matched tubes in the rack to
handle reagent blank, standards and samples. If it is necessary to
correct for color or dissolved organic matter (which will cause color
on heating), a set of duplicate tubes must be used to which all reagents
except the brucine-sulfanilic acid has been added.
8.3 Pipet 10 ml or an aliquot of the samples diluted to 10 ml
into the sample tubes.
8.4 If the samples are saline, add 2.0 ml of the 30 percent
NaCl solution to the reagent blank, standards and samples. For fresh
water samples NaCl may be omitted. Mix contents of tubes of swirling
and place rack in cold water bath (0-10°C).
SEP 1968
-------
5.
8.5 Pipet 10 ml of H2^A solution into each tube and mix by
swirling. Allow tubes to come to thermal equilibrium in the cold bath.
8.6 Add 0.5 ml brucine-sulfanilic acid reagent to each tube
(except the interference control tubes) and carefully mix by swirling,
then place the rack of tubes in the boiling water bath for exactly
25 minutes.
8.7 Remove rack of tubes from the hot water bath and immerse
in the cold water bath and allow to reach thermal equilibrium (20-25°C).
8.8 Dry tubes and read optical density against the reagent blank
at 410 my.
9. Calculation
9.1 Obtain a standard curve by plotting the optical densities
of standards run by the above procedure against mg NO--N. The color
reaction does not always follow Beer's law.
9.2 Subtract the absorbance of the sample without the brucine-
sulfanilic reagent from the absorbance of the sample containing
brucine-sulfanilic acid and read the resultant absorbance in mg NO--N.
Multiply by factor for converting mg per aliquot of sample to mg per liter.
mg/1 NO.,-N = 100° . X mg NO,-N from curve
3 ml sample & 3
AUTOMATED METHOD
10. Application
10.1 This method is applicable to water samples which contain less
than 500 mg/1 calcium. The applicable range of this method is 0.05-10 mg/1
nitrite or nitrate nitrogen. Approximately 20 samples per hour can be
analyzed.
SEP
-------
6.
11. Summary of Method
11.1 This procedure, using the Technicon Auto Analyzer, determines
NO--N by the conventional diazotization—coupling reaction. The NO--N
is reduced with hydrazine sulfate in another portion of the sample and
the nitrite thus formed is determined in the usual manner.
11.2 Subtraction of the NO^-N originally present in the sample
from the total NO»-N found will give the original NO--N concentration
in terms of N02-N.
12. Interferences
12.1 The following table lists the concentration of ions that
cause no interference in the determination of nitrite and nitrate
nitrogen. The same interfering ion concentration applies to either
nitrite or nitrate:
Ion Mg/1 ion not causing interference
Cl~ 30,000
P04~3 50
S~2 Note
NH3-N 80
Mg+2 75
Ca+2 240
Fe+3 30
ABS 60
Note 2. — The apparent NO^ and NOo concentrations varied +
10 percent with concentrations of sulfide ion up to 10 mg/1.
12.2 The pH of the samples should be between 6 and 9.
SEP 1968
-------
7.
13. Apparatus
13.1 Technicon Auto Analyzer consisting of:
13.1.1 Two proportional pumps.
13.1.2 Two colorimeters each with an 8 mm flow-through cell and
520 my filters.
13.1.3 One continuous filter.
13.1.4 One sampler (large).
13.1.5 Two recorders.
13.1.6 One 38° C temperature bath.
13.1.7 Two time delay coils.
14. Reagents
14.1 Color developing reagent. - To approximately 3 liters of distilled
water add 400 ml concentrated phosphoric acid (sp gr 1.834), 60 g
sulfanilamide (H^N-CgH S02 NH2) followed by 3.0 g N(l-Naphthyl)ethylene-
diamine dihydrocholoride. Dilute the solution to 4 liters with distilled
water and store in a dark bottle in the refrigerator. This solution is
stable for approximately 1 month.
Note 3. — It may be necessary to apply heat in order to
dissolve the sulfanilamide.
14.2 Copper sulfate; stock solution. - Dissolve 2.5 g of copper
sulfate (CuSO^ • 5 H20) in distilled water and dilute to 1 liter.
14.3 Copper sulfate; dilute solution. - Dilute 20 ml of stock
solution to 2 liters with distilled water.
14.4 Sodium hydroxide; stock solution. (10 N). - Dissolve 400 g
NaOH in 750 ml distilled water, cool and dilute to 1 liter.
SEP 1968
-------
8.
14.5 Sodium hydroxide (.1.0 N) . - Dilute 100 ml of stock NaOH
solution to 1 liter.
14.6 Sodium hydroxide CO.3 N) . - Dilute 60 ml of stock NaOH
to 2 liters.
14.7 Hydrazine sulfate solution. - Dissolve 54.92 g of hydrazine
sulfate (N2H • H SO.) in 1800 ml of distilled water and dilute to
2000 ml. This solution is stable for approximately 6 months.
CAUTION: Toxic if ingested. Mark container with warning.
14.8 Nitrate Standards
14.8.1 Potassium nitrate; stock standard (1000 mg/1 • NO--N).
Dissolve 7.2180 g of KNO-, oven dried at 100-105° C for 2 hours, in
distilled water and dilute to 1000 ml. Add 1 ml chloroform as a
preservative. Stable for six months.
14.8.2 Potassium nitrate, dilute standard (100 mg/1 NO--N).
Dilute 50 ml of stock KNO, solution to 500 ml in a volumetric flask.
From this dilute solution prepare the following standards in 500 ml
volumetric flasks:
mg/1 N03~N ml standard solution
0.4 2.0
1.0 5.0
1.6 8.0
3.0 15.0
5.0 25.0
7.0 35.0
10.0 50.0
SEP 1968
-------
9.
14.9 Nitrite Standards
14.9.1 Potassium nitrite, stock standard O-OOO mg/1 NO--N).
Dissolve 4.9260 g NaN02, oven dried at 100-105° C for two hours, in
distilled water and dilute to 1000 ml. Add 1 ml chloroform as
preservative. Store in the refrigerator. Stable for one month.
14.9.2 Potassium nitrite, dilute standard (100 mg/1).
Dilute 50 ml of stock NaNO~ solution to 500 ml in a volumetric flask.
From this dilute solution prepare the same volumetric standards as
in 15.3. Prepare fresh each week.
15. Procedure
15.1 Set up the manifold as shown in Figures 1 and 2. Allow
both colorimeter (with the proper filters) and recorder to warm up
for 30 minutes, then run a base line with all reagents, feeding distilled
water through the sample line. Adjust dark current and operative
opening on each colorimeter. Adjust base line to 0.01 optical density.
Place a distilled water wash tube in alternate openings on sampler
and set sample timing at 1.5 minutes.
15.2 Run a 2.0 mg/1 NO--N and a 2.0 mg/1 N02~N standard through
the system to check for 100% reduction of nitrate to nitrite. The two
peaks should be of equal height. If the NO- peak is lower than that
of the N0£ peak, the temperature of the reduction bath should be
increased until they are equal. If the NO- peak is higher than the
nitrate, the temperature should be reduced. When the correct temperature
of the bath has been determined, no further adjustment should be necessary.
SEP 196?
-------
10.
15.3 Arrange standards in sampler in NO--NO- order with increasing
concentration of nitrogen. Place unknown samples in sampler tubes and
place in alternate openings of sampler. A NO- and NO- standard of equal
nitrogen concentration should be placed after every 10 samples as a
further check on the system and to more easily identify peaks.
16. Calculation
16.1 Subtract the NO- concentration in the sample from the total
NO- found (nitrite plus nitrate) on the reduction side to calculate
the NO- concentration in the sample.
17. Precision
17.1 Precision and accuracy data are not available at this time.
References
1. D. Jenkins and L. Medsker, "Brucine Method for Determination of
Nitrate in Ocean, Estuarine, and Fresh Waters". Anal. Chem., 36.
610 (1964).
2. L. Kamphake, S. Hannah, and J. Cohen, "Automated Analysis for
Nitrate by Hydrazine Reduction". Water Research, l> 205 (1967).
SEP
-------
Figure 1. Nitrate-Nitrite Manifold
August 1968
Large Mixing Coil
Double
Delay
Coil
Continuous Filter
Large Mixing Coil
From Figure 2
for N0« Determination
Black Black
ml/min.
2.90 Sample
1-20 Air
0.32 N NaOH
0.42 N NaOH
SAMPLER I
£
£•
2.50 Waste from NO^ Colorimeter
2.50 Waste from N02 Colorimeter
PROPORTIONING
PUMP
HS
Sampling Time: 1.5 Min
Wash Tubes : One
COLORIMETER RECORDER
8 mm Tubular f/c
520 mu Filters
-------
Figure 2. Nitrate-Nitrite Manifold
August 1968
o
u
60
C
• r-l
X
•r-l
S
01
00
"for N02 Determinatiot
^
f
\i/ \L
Large Mixing Coil
, OOOOQMQ X
f M JS f
'PL L..,^
/^\\ n°^!e
1 fc^/ Coil
Z Waste.
R
Y
P
0
Black
G
G
Blue
Y
R
Y
B
0
Black
G
G
Blue
Y
Blue
Blue
Blue
Blue
PROPORTIONING
PUMP
f
gggSSJ j '71 J^
T
SSL 1 ^ iT
ml/min.
„ 0.80 Waste
_ 1.20 Air
^2.90 Dist. H20
" 0.42 N02Sample ' ^
IFrom Filter
(See Figure 1)
\ f
^2.00 Cu Reagent
^2.00 0.30 N NaOH
H 1.60 Hydrazine Reagent
^ 1.20 Air
^ 1.60 Dist. H20
^ 1.60 Color Reagent
To N02 Manifold
Proceed to Figure 1
Sampling Time: 1.5 Min.
Wash Tubes : One
COLORIMETER
8 mm Tubular f/c
520 mn Filters
RECORDER
-------
Method
Reference
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Storet Parameter No. 00615
Parameter : Nitrogen, Nitrite (mg/1)
Manual Method: colorimetric diazotization, modified.
Manual Automated Method: same as manual.
Automated Method: included in automated nitrate method
for fresh water.
1. Standard Methods for the Examination of Water and
Wastewater, 12th ed., APHA, Inc., N.Y., 1965,
205-208.
2. ASTM Book of Standards, Part 23, 1967
D1254-67, pp. 256-260.
Modifications: New method write-up. See attached.
Date: September 1968
-------
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHOD
for
Nitrogen-Nitrite
Scope
1. These methods are applicable for the determina-
tion of nitrite ion in water, wastewater, sewage,
sludges, and saline water by colorimetric methods.
Official Method - Colorimetric method diazota-
tion with sulfanilamide and N-(l-naphthyl)-
ethylenediamine.
Official Method - Automated - same chemistry as
manual - to be developed for .010 tng/1 sensitivity.*
Preservation
?.. Samples should be preserved at time of collection
with 1 ml of chloroform per 100 ml sample or 40 mg
Hg/ml as mercuric chloride. Store at 4°C. DO NOT
PRESSRV2 WITH SULFURIC ACID.
Summary of Method
3. The diazonium compound formed by diazotation of
sulfanilamide by nitrite ion in water under acid
conditions is coupled with N-(l-naphthyl)-
*Automated nitrite method is included in the automated
nitrate method for fresh waters.
SEP 1368
-------
ethylenedtamine to produce a reddish-purple color
which is read in a spectrophotometer at 520 mn.
Interferences
4. There are very few known interferences at concen-
trations less than 1000 times that of the nitrite;
however, recent addition of strong oxidant or
reductants to the sample will readily affect the
nitrite concentration.
Determination of Nitrite-Nitrogen Ion in Aqueous Medium
Reagents
5. a) Color reagent: To 400 ml of distilled water, while
stirring on a magnetic mixer, add 50 ml cone. HCl,
5.0 g of sulfanilamide and 0.5 g of N-(l-naphthyl)-
ethylenediamine dihydrochloride. Stir until
dissolved and dilute to 500 ml.
b) Sodium acetate buffer, 2M: To 50 ml, while stirring
on a magnetic mixer, add 27.4 g of NaC2Ho09.3 H^O.
Stir until dissolved and dilute to 100 ml.
c) Stock nitrite-nitrogen standard (100 mg/1
Dissolve 0.4926 g sodium nitrite, anhydrous
and dilute to 1000 ml with distilled water.
Preserved with 2 ml chloroform per liter. Stable
one week.
SEP 1968
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Apparatus
6. a) Spectrophotometer or filter photometer suited for
use in range of 515 to 530 tnp.
b) Nessler tubes of 50 ml volume.
Calibration
7. a) Prepare in 50 ml Nessler tubes a reagent blank and
five standards in the desired concentration range
from the 100 mg/1 NC^-N standard and dilute to
about 40 ml. The slope of the curve should be
checked each day with a blank and one standard.
b) To each add 1.0 ml of color reagent and 1.0 ml of
acetate buffer. Dilute to 50 ml and allow color
to develop for 10 minutes. The color reaction
medium should be between pH 2.0 and ?.5.
c) An estimate of the color density which will permit
approximately 25% transmission in various size
cells can be obtained from the following:
ml stock mg/50 ml mg/1 cell length
standard N09-N N02-N cm
2.0
4.0
20.0
.002
.004
.020
.040
.080
.40
10.
5.
1.
d) clead in Spectrophotometer at 520 mn against
reagent blank.
SEP !S68
-------
Procedure
8. a) If the sample has a pH greater than 10, adjust
it to approximately pH 7 with acetic acid (1:3).
b) Filter sample through Whatman No. 42 paper or
.45 (a membrane filter, depending on the amount
of suspended solids in sample.
c) To 40 ml (or aliquot diluted to 40 ml) add 1.0 ml
color roagent and 1.0 ml of buffer. Dilute to
50 ml mark and mix.
d) Read color after 10-30 minutes in spectrophotometer
at 520 mp against reagent blank in same size cells
as used with nitrite-nitrogen standards.
Calculations
9. a) The colorimetric reaction obeys Beer-Lambert's
law so that in plotting the absorbancy of the
standards against the concentration, a straight
line results.
b) Calculate the concentration of nitrite-nitrogen
ion in the sample in milligram per liter as follows:
mg/1 NC>2-N = absorbance of sample x mg/1 standard x
absorbance standard
1000
ml sample
Precision
10. To be evaluated by "round robin" testing.
SEP 1968
-------
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Storet Parameter No. OQ3QQ
Parameter : Oxygen Dissolved (mg/1)
Method
: Volumetric, Winkler azide, modified.
Reference : 1. Standard Methods for the Examination of Water and
Wastewater, 12th ed., APHA, Inc., N.Y., 1965.
406-410.
2. ASTM Book of Standards, Part 23, 1967
D888, pp. 114-115.
Modifications: Full bottle technique with normality adjusted
to 0.0375N sodium thiosulfate. See new method
write—up.
Date: September 1968
-------
Parameter
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Storet Parameter No. 00666
: Phosphorus, Soluble (mg/1)
Method
Colorimetric, mixed reagent, filtered with persulfate
digestion.
Reference
Modifications:
1. Gales, M. E. Jr., Julian, E. C., and Kroner, R. C.,
"Method for Quantitative Determination of Total
Phosphorus in Water." J. AWWA, .58(10), 1363-1368
(1966).
2. Murphy, J. and Riley, J. P., "A Modified Single
Solution Method for the Determination of Phosphate
in Natural Waters," Anal. Chim. Acta, 27. 31-36 (1962),
New method write-up.
Date; September 1968
-------
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Storet Parameter No. to be assigned
Parameter * Phosphorus, Soluble, Ortho (mg/1)
Method
Colorimetric, mixed reagent, filtered.
Reference
Murphy, J. and Riley, J. P., "A Modified Single
Solution Method for the Determination of Phosphate
in Natural Waters." Anal. Chim. Acta, 27. 31-36 (1962)
Modifications: New method write-up.
Date: September 1968
-------
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Parameter
Storet Parameter No. 00665
: Phosphorus, Total (mg/1)
Method
: Colorimetric, mixed reagent, with persulfate digestion
Reference
Modifications:
1. Gales, M. E. Jr., Julian, E. C., and Kroner, R. C.,
"Method for Quantitative Determination of Total
Phosphorus in Water." J. AWWA, j>8(10), 1363-1368
(1966).
2. Murphy, J. and Riley, J. P., "A Modified Single
Solution Method for the Determination of Phosphate
in Natural Waters." Anal. Chim. Acta, .27, 31-36 (1962)
New method write-up.
Date; September 1968
-------
Parameter
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Storet Parameter No. to be assigned
: Phosphorus, Total, Ortho (mg/1)
Method
Colorimetric, mixed reagent.
Reference
Murphy, J. and Rlley, J. P., "A Modified Single
Solution Method for the Determination of Phosphate
in Natural Waters." Anal. Chim. Acta, 2]_t 31-36 Q-962).
Modifications: New method write-up.
Date: September 1968
-------
August 1968
Analytical Quality Control Branch
FWPCA OFFICIAL INTERIM METHOD
PHOSPHORUS
I. Scope
I.I These methods cover the determination of specified forms of
phosphorus in surface waters, saline waters, industrial waters,
and sewage-type water samples. They may be applicable to
sediment-type samples, sludges, algal blooms etc., but
sufficient data is not available at this time to warrant such
usage when measurements for total phosphorus content are
requi red.
1.2 The methods are based on reactions that are specific for the
orthophosphate ion. Thus, depending on the prescribed pre-
treatment of the sample, the various forms of phosphorus
given in Figure I may be determined. These forms are, in
turn, defined in Table I.
1.2.1 Except for in-depth and detailed studies, the most
commonly measured forms of phosphorus are total and
soluble phosphorus, and total and soluble ortho-
phosphate. Hydro IyzabIe phosphorus is normally found
only in sewage-type samples and insoluble forms of
phosphorus, as noted, are determined by calculation.
1.3 The methods are usable in the 0.01 to 0.5 mg/I P range.
2. Definitions
2.1 The various forms of phosphorus are defined in Table I.
SEP 1358
-------
Residue
SAMPLE
Filter
(No Fi It rat- inn")
Direct
Colorimetry
Total
Orthophosphate
H2S04
Hydrolysis &
Colorimetry
Total Hydrolyzable
& Orthophosphate
\
Direct
Colorimetry
Soluble
Orthophosphate
J
Hydrolysis
& Colorimetry
Soluble Hydrolyzable
& Orthophosphate
\
Persulfate
Digestion
& Colorimetry
Total Soluble
Phosphorus
\
Persulfate
Digestion
& Colorimetry
Total
Phosphorus
Figure 1. Analytical Scheme For Differentiation of Phosphorus Forms.
^953
-------
-3-
TABLE I
PHOSPHORUS TERM INOLOGY
I. Total Phosphorus (P-T) - all of the phosphorus present in the
sample, regardless of form, as measured by the persulfate
digestion procedure.
a. Total Orthophosphate (P-T,ortho) - inorganic phosphorus
dCPO.) 3 in the sample as measured by the direct color-
imetric analysis procedure.
b. Total Hydrolyzable Phosphorus (P-T,hydro) - phosphorus in
the sample as measured by the suIfuric acid hydrolysis
procedure, and minus pre-determined total orthophosphates.
This hydrolyzable phosphorus includes polyphosphates C(PoO-,) ,
(P,0._) , etc.] + some organic phosphorus.
c. Total Organic Phosphorus (P-T,org) - phosphorus (inorganic +
oxidizable organic) in the sample as measured by the
persulfate digestion procedure, and minus total hydrolyzable
phosphorus and orthophosphate.
2. Total Soluble Phosphorus (P-S,T) - all of the phosphorus present
in the filtrate of a sample filtered through a phosphorus-free
filter of 0.45 micron pore size and measured by the persulfate
digestion procedure.
a. Soluble Orthophosphate (P-S,ortho) - as measured by the
direct colorimetric analysis procedure.
SEP 1368
-------
-4-
lAbLE i (Contd.)
b. Soluble Hydrolyzable Phosphorus (P-S,hydro) - as measured
by the sulfuric acid hydrolysis procedure and minus pre-
determined soluble orthophosphates.
c. Soluble Organic Phosphorus (P-S,org) - as measured by the
persulfate digestion procedure, and minus soluble hydro-
lyzable phosphorus and orthophosphate.
3. The following forms, when sufficient amounts of phosphorus are
present in the sample to warrant such consideration, may be
caIculated:
a. Total Insoluble Phosphorus (P-I,T) = (P-T) - (P-S,T).
(I) Insoluble Orthophosphate (P-l,ortho) = (P-T,ortho) -
(P-S,ortho).
(2) Insoluble Hydrolyzable Phosphorus (P-l,hydro) =
(P-T,hydro) - (P-S,hydro).
(3) Insoluble Organic Phosphorus (P-l,org) = (P-T,org) -
(P-S,org).
4. All phosphorus forms shall be reported as P, mg/I.
SEP 1968
-------
-5-
3. Samp i i ng
3.1 Samples should be taken in a location that is the most
representative of the waters in the area being sampled.
If benthic deposits are present in the area being sampled,
great care should be taken not to include these deposits.
3.2 Sample containers may be of plastic material, such as
cubitainers, or of Pyrex glass. In both cases, high iron
concentrations interfere through the formation of clumps
in the bottom of the sample.
3.3 If the analysis cannot be performed the same day of
collection, the sample should be preserved in one of the
following manners (Note I):
3.3.1 Five ml of chloroform per liter of sample.
3.3.2 Acidification with sulfuric acid (used only when
not measuring for all forms of phosphorus).
3.3.3 Quick-freezing of sample.
3.3.4 Five ml of saturated solution of mercury chloride
per gallon of sample.
Note I - Sufficient data is not available on these
suggested preservatives to state a preference at
this time.
4. Summary of Method [£)oI orimetric Single Reagent Method]
4.1 Ammonium molybdate and potassium antimony I tartrate react
in an acid medium with dilute solutions of phosphorus to
SEP 1968
-------
-6-
form an antimony-phosphate-moiybdate complex. This
complex is reduced to an intensely blue-colored complex
by ascorbic acid. The color is proportional to the
phosphorus concentration.
4.2 Only orthophosphate forms a blue color in this test.
Polyphosphates (and some organic phosphorus compounds)
may be converted to the orthophosphate form by suIf uric-
acid-hydrolysis. Organic phosphorus compounds may be
converted to the orthophosphate form by persulfate
digestion.
5. Interferences
5.1 It is reported that no interference is caused by
copper, iron, or silicate at concentrations many times
greater than their greatest reported concentration in
sea water.
5.2 The salt error for samples ranging from 5 to 20 percent
salt content was found to be less than I percent
5.3 Arsenate, in concentrations greater than found in sea water,
does not interfere :
1963
-------
—7-
TABLE 2
Effect of Other Ions on Determination of Phosphate
Concentration Optical density at 822 my
Ion
—
Copper( 1 1 )
1 ron ( 1 1 1 )
Sil icate
Arsenate
Arsenate
mg/l
^
10
50
10
1.0
0.02
No added P04/P
0.012
0.018
0.017
0.014
1 . 1 44a
0.020
+ 10 ygP04/P
0.593
0.585
0.598
0.594
I.7523
0.614
(4-cm eel Is)
Di f ference
0.581
0.567
0.581
0.580
0.608
0.594
a
Measured in I-cm cell calculated for 4-cm cells.
6. Apparatus
6.1 Photometer - A spectrophotometer or filter photometer suitable
for measurements at 880 my, and providing a light path of I
inch (2.54 cm) or longer, should be used.
6.2 Acid-washed glassware: All glassware used in the determination
should be washed with hot 1:1 HCI and rinsed with distilled
water. The acid-washed glassware should be filled with
distilled water and treated with all the reagents to remove
the last traces of phosphorus that might be adsorbed on the
glassware. Preferably, this glassware should be used only for
the determination of phosphorus and after use it should be
rinsed with distilled water and kept covered until needed again..
If this is done, the treatment with 1:1 HCI and reagents is
only required occasionally. Commercial detergents should never be
used.
StP 1363
-------
-8-
7.1 Sulfuric acid solution, 5N: Dilute 70 ml of cone. H-SO.
with distilled water to 500 ml.
7.2 Potassium antimony I tartrate solution: Weigh 1.3715 g
KCSbOC.H.O... 1/2 H00, dissolve in 400 ml distilled water
446 Z.
in 500 ml volumetric flask, dilute to volume. Store in
glass-stoppered bottle.
7.3 Ammonium molybdate solution: Dissolve 20 g (NH.),.Mo7074.4 hLO
in 500 ml distilled water. Store in a plastic bottle at 4° C.
7.4 Ascorbic acid, O.IM: Dissolve 1.76 g of ascorbic acid in
100 ml of distilled water. The solution is stable for
about a week if stored at 4° C.
7.5 Combined reagent: Mix the above reagents in the following
proportions for 100 ml of the mixed reagent: 50 ml of
5N HUSO., 5 ml of potassium antimony I tartrate solution, 15
ml of ammonium molybdate solution, and 30 ml of ascorbic
acid solution. Mix after addition of each reagent. All
reagents must reach room temperature before they are mixed
and must be mixed in the order given. If turbidity forms
in the combined reagent, shake and let it stand for a few
minutes until the turbidity disappears before proceeding.
The reagent is stable for one week if stored at 4° C.
7.6 Primary phosphorus standard: Dissolve in distilled water
0.2197 g of potassium dihydrogen phosphate, KH_PO. which
£. 4,
SEP 1958
-------
—9—
has been dried in an oven at 105° C. Dilute.the solution
to 1,000 ml; 1.00 ml equals 0.05 mg P.
7tl Working phosphorus standard: Dilute 10.0 ml of stock
phosphorus solution to 1,000 ml with distilled water;
I.00 ml equals 0.5 yg P.
7.8 Strong-acid solution: Slowly add 310 ml cone. H-SO. to
600 ml distilled water. When cool, dilute to I liter.
7.9 Ammonium persulfate.
8. CaIibration
8.1 Standard curve: Prepare a series of at least nine standard
phosphorus solutions to cover the range from 0 to 0.50 P
mg/l. Make up the standards by diluting suitable volumes
of working phosphorus solution to 50 ml with distilled water.
The following dilutions are suggested:
ml of Working
Phosphorus Standard Cone., mg/l
0 0.00
1.0 0.01
3.0 0.03
5.0 0.05
10.0 0.10
20.0 0.20
30.0 0.30
40.0 0.40
50.0 0.50
8.2 Develop color in the series of standards and blank of dis-
tilled water as directed in 9. Procedure. Measure the
color absorbance of each standard at 880 my with a spectro-
photometer, using the reagent blank as the reference solution.
SEP 1963
-------
-10-
P!ot the absorbance values as ordinates and the corre-
sponding phosphorus concentrations as abscissas.
8.3 Process standards and blank exactly as the samples.
Run at least a blank and two standards with each series
of samples. If the standards do not agree within ± 2%
of the true value, prepare a new calibration curve.
9. Procedure
9.1 Total Phosphorus
9.1.1 Add I ml of strong-acid solution to a 50-ml
sample in a 125-ml Erlenmeyer flask.
9.1.2 Add 0.4 gram of ammonium persulfate.
9.1.3 Boil gently on a pre-heated hot plate for
approximately 30-40 minutes or until a final
volume of about 10 ml is reached. Do not allow
sample to go to dryness. Alternatively, heat
for 30 minutes in an autoclave at 121° C (15-
20 psi).
9.1.4 Cool and dilute the sample to 50 ml.
9.1.5 The sample is now ready for determination of
phosphorus as outlined in 9.3 Orthophosphate.
9.2 Hydrolyzable Phosphorus
9.2.1 Add I ml of strong-acid solution to a 50-ml
sample in a 125-ml Erlenmeyer Flask.
SEP 1S58
-------
9.2.2 Boil gently on a pre-heated hot plate for
approximately 30-40 minutes or until a final
volume of about 10 ml is reached. Do not allow
sample to go to dryness. Alternatively, heat
for 30 minutes in an autoclave at 121° C (15-
20 psi).
9.2.3 Cool and dilute the sample to 50 ml.
9.2.4 The sample is now ready for determination of
phosphorus as outlined in 9.3 Orthophosphate.
9.3 Orthophosphate
9.3.1 Add I drop of phenolphthalein indicator to the
50.0 ml sample. If a red color develops, add
strong-acid solution drop-wise to just discharge
the color.
9.3.2 Add 8.0 ml of combined reagent to sample and mix
thoroughly. After a minimum of ten minutes, but
no longer than thirty minutes, measure the color
absorbance of each sample at 880 my with a spectre-
photometer, using the reagent blank as the reference
solution.
10. Calculation
10.I Obtain concentration value of sample directly from prepared
standard curve. Report results as P, mg/I.
II. Precision and Accuracy
I I.I Complete precision and accuracy data are not available
SEP
1SG3
-------
-12-
at this time. In a comparative study of three modifi-
cations of the Single Reagent Method, however, the
following results were obtained.
I I.I.I On a variety of natural water samples, both
salt and fresh, a precision of I.10% (coefficient
of variation) and an accuracy of 0.43$ (deviation
from amount added) were obtained at a 0.2 mg/l P
concentration.
References
I. J. Murphy and J. Riley, "A Modified Single Solution Method
for the Determination of Phosphate in Natural Waters."
Anal. Chim. Acta., 27_, 31 (1962).
2. M. Gales, Jr., E. Julian, and R. Kroner, "Method for
Quantitative Determination of Total Phosphorus in Water."
Jour AWWA, 58^, No. 10, 1363 (1966).
3. J. Winter and R. Booth, "A Comparison of Three Modifications
of the Single Reagent Method for Phosphorus, Ortho, Soluble."
Analytical Quality Control Branch, Division of Research,
Federal Water Pollution Control Administration (August 1968).
SEP
-------
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Storet Parameter No. 00085
Parameter : Odor, Threshold, Hot (60 C)
Method : Dilution Series, modified.
Reference : Standard Methods for the Examination of Water and
Wastewater, 12th ed., APHA, Inc., N.Y., 1965,
304-311.
Modifications: Method in preparation. Use reference method until
ready.
Date: SePtember 1968
-------
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Storet Parameter No. to be assigned
Parameter : Odor, Threshold, Room Temperature
Method : Dilution Series, modified.
Reference : Standard Methods for the Examination of Water and
Wastewater, 12th ed., APHA, Inc., N.Y., 1965,
304-311.
Modifications: Method in preparation. Use reference method until
ready.
Date; September 1968
-------
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Storet Parameter No. 00550
Parameter : Oil and Grease (mg/1)
Method : Soxhlet Extraction Method .
Reference : Standard Methods for the Examination of Water and
Wastewater, 12th ed. , APHA, Inc., N.Y., 1965,
384-385.
Modifications: Page 384 Delete only the heading, "1. General Discussion".
Insert the following heading and paragraph:
1. Scope and Application
In the determination of grease, an absolute quantity of a
specific substance is not measured. Rather, groups of substances
with similar physical characteristics are determined quantitatively,
based on their mutual solubility in the solvent used. Grease,
therefore, can be said to include fats, waxes, oils, and any other
nonvolatile material extracted by hexane from an acidified sample
of water or waste water.
Sampling and Storage; When possible, collect representative
samples in a wide-mouth bottle calibrated to hold a measured volume,
and perform the initial steps of the procedure in the sample bottle.
When information is required concerning the average grease concentration
of a waste over an extended period, the examination of individual
portions collected at prescribed time intervals can be used to
eliminate losses of grease on sampling equipment during the collection
of a composite sample.
Date; September 1968
-------
2.
Federal Water Pollution Control Administration
OFFICIAL INTERIM METHODS
Modifications Cont'd:
Pa%e 385 Delete paragraph 4.1.
Insert as paragraph 4.1:
Collect sample in a wide-mouth bottle and acidify
pH 1.0 with cone. HC1.
Page 385 Section 6. Precision and Accuracy
Delete paragraph entirely.
Insert the following sentence:
Precision and accuracy will be determined by round
robin testing.
SEP
1958
-------
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Storet Parameter No. 00681
Parameter : Organic Carbon, Dissolved (mg/1)
Method
Dow Beckman-type organic carbon analyzer.
Reference : ASTM Book of Standards, Part 23, 1967
D2579-67T, pp. 716-719.
Modifications: None
Date; September 1968
-------
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Storet Parameter No. 00680
Parameter : Organic Carbon, Total (mg/1)
Method
: Dow Beckman-type organic carbon analyzer.
Reference
: ASTM Book of Standards, Part 23, 1967
D2579-67T, pp. 716-719.
Modifications: None
Date; September 1968
-------
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Parameter
Storet Parameter No. QQ400
pH
Method
Instrumental, glass/standard calomel electrodes.
Reference
1. Standard Methods for the Examination of Water and
Wastewater, 12th ed., APHA, Inc., N.Y., 1965,
226-228.
2. ASTM Book of Standards, Part 23, 1967
289-299.
Modifications: None
Date; September 1968
-------
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Parameter
Storet Parameter No. 32730
Phenolics (mg/1)
Method
Reference
"Phenolic Compounds in Industrial Water and
Industrial Waste Water
Method A. Chloroform Extraction Method
Method B. Direct Colorimetric Method"
ASTM Book of Standards, Part 23, 1967
D1783-62, pp. 430-436.
Modifications: None
Date; September 1968
-------
Method
Reference
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Storet Parameter No. 00935
Parameter : Potassium, (mg/1)
1. Atomic absorption.
2. Flame photometry.
1. Method is specific to the particular instrument.
General procedure is being selected.
2. Standard Methods for the Examination of Water and
Wastewater, 12th ed. , APHA, Inc., N.Y., 1965,
238-240.
Modifications: None
Date: September 1968
-------
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Storet Parameter No. to be assigned
Parameter : Selenium, Dissolved (yg/1)
Method : Filtration through 0.45 y membrane filter.
Measurement by diaminobenzidine colorimetric method.
Reference : Standard Methods for the Examination of Water and
Wastewater, 12th ed., APHA, Inc., N.Y., 1965,
251-253.
Modifications: Use of 0.45 y membrane filter only.
Date; September 1968
-------
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Storet Parameter No. 01145
Parameter : Selenium, Total (yg/1)
Method
: Diaminobenzidine, colorimetric.
Reference : Standard Methods for the Examination of Water and
Wastewater, 12th ed., APHA, Inc., N.Y., 1965,
251-253.
Modifications: None
Date; September 1968
-------
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Storet Parameter No. to be assigned
Parameter : Silicon (Silica), Dissolved (yg/1)
Method : Filtration through 0.45 u membrane filter.
Measurement by molybdate blue.
Reference : "Methods for Collection of Analysis of Water Samples",
Geological Survey Water-Supply Paper 1454, 1960,
pp. 259-261.
Modifications: Use of 0.45 u membrane filter only.
Date; September 1968
-------
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Storet Parameter No. 01140
Parameter : Silicon (Silica), Total (yg/1)
Method
Molybdate blue
Reference : "Methods for Collection of Analysis of Water Samples",
Geological Survey Water-Supply Paper 1454, 1960,
pp. 259-261.
Modifications: None
Date: SePtember 1968
-------
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Parameter
Storet Parameter No. 00930
Sodium (mg/1)
Method
Reference
Modifications:
1. Atomic absorption.
2. Flame photometry.
1. Method is specific to the particular instrument.
General procedure is being selected.
2. Standard Method for the Examination of Water and
Wastewater, 12th ed., APHA, Inc., N.Y., 1965,
274-277.
None
Date: September 1968
-------
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Storet Parameter No. Q0520
Parameter : Solids, Dissolved, Volatile (mg/1)
Method
: Gravimetric by difference, modified.
Reference : Standard Methods for the Examination of Water and
Wastewater, 12th ed., APHA, Inc., N.Y., 1965,
247-248.
Modifications: Filter by 0.45 y membrane filter for dissolved/suspended
volatile solids.
Date: September 1968
-------
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Storet Parameter No. 00500
Parameter : Solids, Total (mg/1)
Method : Gravimetric, modified.
Reference : Standard Methods for the Examination of Water and
Wastewater, 12th ed., APHA, Inc., N.Y., 1965,
244-245.
Modifications: Evaporate at 103-105°C only.
Date: SePtember 1968
-------
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Storet Parameter No. QQ515
Parameter : Solids, Total Dissolved (mg/1)
Method
: Gravimetric, modified.
Reference : Standard Methods for the Examination of Water and
Wastewater, 12th ed., APHA, Inc., N.Y., 1965,
247-248.
Modifications: Use of 0.45 y membrane filter only, for filtrations.
Glass pre-filter may be used to speed filtration.
Evaporate at 103-105°C only.
Date: September 1968
-------
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Storet Parameter No. 00530
Parameter : Solids, Total Suspended (mg/1)
Method
: Gravimetric, modified.
Reference : Standard Methods for the Examination of Water and
Wastewater, 12th ed., APHA, Inc., N.Y., 1965,
246-247.
Modifications: Filter by 0.45 y membrane filter only,
evaporate at 103-105°C only.
Date; September 1968
-------
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Storet Parameter No. 00535
Parameter : Solids, Suspended, Volatile (mg/1)
Method
: Gravimetric by difference, modified.
Reference : Standard Methods for the Examination of Water and
Uastewater, 12th ed., APHA, Inc., N.Y. , 1965,
247-248.
Modifications: Filter by 0.45 y membrane filter for dissolved/suspended
volatile solids.
September 1968
Date: v
-------
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Storet Parameter No. 00505
Parameter : Solids, Total, Volatile (mg/1)
Method
• Gravimetric, modified.
Reference : Standard Methods for the Examination of Water and
Wastewater, 12th ed., APHA, Inc., N.Y., 1965,
247-248.
Modifications: Filter by 0.45 y membrane filter only for
filterable/non-filterable volatile solids.
Date- SePtember 1968
-------
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Storet Parameter No. 00945
Parameter : Sulfate (mg/1)
Method
Turbidimetric, modified.
Reference : Standard Methods for the Examination of Water and
Wastewater, 12th ed., APHA, Inc., N.Y., 1965,
291-293.
Modifications: Use of proprietary reagents is acceptable.
Date; September 1968
-------
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Storet Parameter No. 00746
Parameter : Sulfide, Dissolved (mg/1)
Method
Reference
: In preparation.
Modifications:
Date: September 1968
-------
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Storet Parameter No. 00010
Parameter : Temperature (°Centigrade)
Method : Thermometer, (mercury, dial, or thermistor).
Reference : Standard Methods for the Examination of Water and
Wastewater, 12th ed., APHA, Inc., N.Y., 1965,
433.
Modifications: None
Date: SePtember 1968
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Method
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Storet Parameter No. 00076
Parameter : Turbidity, Nephelometric
: Selected instrument such as Hach 2100, based on
method specifications.
Reference : New method write-up. See attached.
Modifications: None
Date: September 1968
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Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHOD
for
Turbidity
Method Selection
To be measured by selected turbidimeter only. COMVAQC, FWPCA
has developed the following specifications for a turbidimeter acceptable
for use in the Administration. Instruments are now coming on to the
market which can meet these specifications. No instrument listing is made
since the instrument companies make quick model and design changes and
any listing would be unintentionally incomplete and possibly incorrect.
Background
Clear water is important in those industries where the product
is destined for human consumption or for a large number of industrial
uses. Beverage producers, food processors, and treatment plants
drawing upon a surface water supply commonly rely on coagulation,
settling, and filtration measures to insure an acceptable effluent.
Turbidity in water is caused by the presence of suspended matter,
such as clay, silt, finely divided organic and inorganic matter,
plankton, and other microscopic organisms. Turbidity should be clearly
understood to be an expression of the optical property of a sample
which causes light to be scattered and absorbed rather than transmitted
in straight lines through the sample. Attempts to correlate turbidity
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with the weight concentration of suspended matter are impractical, as
the size, shape, and refractive index of the particulate materials are
of great importance optically but bear little direct relationship to
the concentration and specific gravity of the suspended matter.
The standard method for the determination of turbidity has
been based on the Jackson Candle turbidimeter. Howerver, the lowest
turbidity value which can be measured directly on this instrument is
25 units. With turbidities of treated water generally falling within
the range 0-5 units, indirect, secondary methods have been required to
obtain turbidities on such samples. Unfortunately no instrument has
been devised which will duplicate the results obtained on the Jackson
Candle turbidimeter for all samples. Owing to fundamental differences
in optical systems, the results obtained with different types of
secondary instruments will frequently not check closely with one
another even though the instruments are all pre-calibrated against
the Jackson Candle turbidimeter.
A further cause of discrepancies in turbidity analysis is the
use of suspensions of different types of particulate matter for prep-
aration of instrumental calibration curves. As with the water
samples, prepared suspensions have different optical properties
depending upon the particle size distributions, shapes, and refractive
indices. Most commercial turbidimeters available for measuring low
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turbidities give comparatively good indications of the intensity of
light scattered in one particular direction, predominately at right
angles to the incident light. Since there is no direct relationship
between the Jackson Candle turbidity and the intensity of light
scattered at 90°, there is no valid basis for the practice of calibrating
the 90° turbidimeters in terms of Jackson units.
1. General Discussion
1.1. Principle: The method presented below is based upon a comparison
of the intensity of light scattered by the sample under defined conditions
with the intensity of light scattered by a standard reference suspension
under the same conditions. The higher the intensity of scattered light,
the higher the turbidity. Formazin polymer, which has gained acceptance
as the turbidity standard reference suspension in the brewing industry,
is also used as the turbidity standard reference suspension for water.
It is easy to prepare and is more reproducible in its light scattering
properties than the clay or turbid natural water standards previously
used. The turbidity of a particular concentration of Formazin suspension
is defined as 40 units. This same suspension of Formazin has an
approximate turbidity of 40 units when measured on the Jackson Candle
turbidimeter, therefore turbidity units based on the Formazin
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prcparation will approximate those derived from the Jackson Candle
turbidimeter but will not be identical to them.
1.2. Interference: The determination of turbidity is applicable
to any water sample that is free of debris and coarse sediments which
settle out rapidly, although dirty glassware, the presence of air
bubbles, and the effects of vibrations which disturb the surface
visibility of the sample will lead to false results. The presence of
"true color", that is the color of the water which is due to dissolved
substances which absorb light, will cause measured turbidities to be
low. This effect is generally not significant with treated water.
1.3. Storage: It is preferable to determine turbidity on the same
day the sample is taken. If longer storage is unavoidable, however,
samples may be stored in the dark up to 24 hr. For even longer storage,
treat 1 liter of sample with Ig mercuric chloride. Prolonged storage
before measurement is not recommended as irreversible changes in
turbidity may occur. All samples should be vigorously shaken before
examination.
2. Apparatus
2.1 The turbidimeter shall consist of a nephelometer with light
souroe for illuminating the sample and one or more photoelectric
detectors with a readout device to indicate the intensity of light
scattered at right angles to the path of the incident light. The
turbidimeter should be so designed that little stray light reaches the
detector in the absence of turbidity and should be free from significant
drift after a short warm-up period. The sensitivity of the instrument
should permit detection of turbidity differences of 0.02 unit or less
in waters having turbidities less than 1 unit. The instrument should SEP 1963
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mcasurc. from 0-40 units turbidity. Several ranges will be necessary
to obtain both adequate coverage and sufficient sensitivity for low
turbidities.
The sample tubes to be used with the available instrument must be
of clear, colorless glass. They should be kept scupulously clean,
both inside and out, and discarded when they become scratched or etched.
They must not be handled at ail where the light strikes them, but
should be provided with sufficient extra length, or with a protective
case, so that they may be handled. The tubes should be filled with
samples and standards which have been thoroughly agitated, and sufficient
time should be allowed for bubbles to escape.
Differences in physical design of turbidimeters will cause
differences in measured values for turbidity even though the same
suspension is used for calibration. To minimize such differences,
the following design criteria should be observed:
a. Light source - tungsten lamp operated at not less than 85% of
rated voltage or more than rated voltage.
b. Distance traversed by incident light and scattered light within
the sample tube - total not to exceed 10 cm.
c. Angle of light acceptance of the detector - centered at 90° to
the incident light path and not to exceed ± 30° from 90°.
d. Maximum turbidity to be measured - 40 units.
3. Reagents
3.1. Turbidity-free water: Pass distilled water through a
membrane filter having a pore size no greater than 100 mu if such
filtered water shows a lower turbidity than the distilled water. Discard
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the first 200 ml collected. Otherwise, use the distilled water.
3.2. Stock turbidity suspension:
a. Solution (I): Dissolve l.OOOg hydrazine sulfate, (NH2)2
in distilled water and dilute to 100 ml in a volumetric flask.
b. Solution (II): Dissolve lO.OOg hexamcthylenetetramine in
distilled water and dilute to 100 ml in a volumetric flask.
c. In a 100 ml volumetric flask, mix 5.0 ml solution (I) with
5.0 ml solution (II). Allow to stand 24 hours at 25 ± 3° C,
then dilute to the mark and mix.
3.3. Standard turbidity suspension: Dilute 10.00 ml stock
turbidity suspension to 100 ml with turbidity free water. The turbidity
of this suspension is defined as 40 units.
3.4. Dilute turbidity standards: Dilute portions of the standard
turbidity suspension with turbidity-free water as required.
A new stock turbidity suspension should be prepared each month. The
standard turbidity suspension and dilute turbidity standards should be
prepared weekly by dilution of the stock turbidity suspension.
4. Procedure:
4.1. Turbidimeter calibration: The manufacturer's operating
instructions should be followed. Measure standards on the turbidimeter
covering the range of interest. If the instrument is already calibrated
in standard turbidity units, this procedure will check the accuracy of
the calibration scales. At least one standard should be run in each
instrument range to be used. Some instruments permit adjustment of
sensitivity so that scale values will correspond to turbidities.
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Rcliancc on a manufacturer's solid scattering standard for setting
overall instrument sensitivity for all ranges is not an acceptable
practice unless the turbidimetcr has been shown to be free of drift
on all ranges. If a pre-calibrated scale is not supplied, then cali-
bration curves should be prepared for each range of the instrument.
4.2. Turbidities less than 40 units: Shake the sample to thoroughly
disperse the solids. Wait until aj.r bubbles disappear than pour the
sample into the turbidimeter tube. Read the turbidity directly from
the instrument scale or from the appropriate calibration curve.
4.3. Turbidities exceeding 40 units: Dilute the sample with one
or more volumes of turbidity-free water until the turbidity falls below
40 units. The turbidity of the original sample is then computed from
the turbidity of the diluted sample and the dilution factor. For
example, if 5 volumes of turbidity-free water were added to 1 volume
of sample, and the diluted sample showed a turbidity of 30 units, then
the turbidity of the original sample was 180 units.
5. Interpretation of Results
5.1 Turbidity readings are reported in accordance with the
following:
Turbidity
Range ,
units
0.0-1.0
1-10
10-40
40-100
100-400
400-1000
>1000
Record
to nearest:
0.05
0.1
1
5
10
50
100
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—8—
5.2. For comparison of water treatment efficiencies, it may be
desirable to estimate more closely than is specified in the table:
but, because of the uncertainties and discrepancies in turbidity
measurements, it cannot be expected that two or more laboratories will
duplicate results on the same sample more closely than specified.
SEP
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Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Storet Parameter No. to be assigned
Parameter : zinc, Dissolved
Method : Filtration through. 0.45 p membrane filter .
Measurement by atomic absorption.
Reference : Method is specific to the particular instrument.
General procedure is being selected.
Modifications: None
Date: SePtemher 1468
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Parameter
Federal Water Pollution Control Administration
Analytical Quality Control Branch
OFFICIAL INTERIM METHODS
for
Analyses of Surface Water Samples
Storet Parameter No. 01090
Zinc, Total
Method
Atomic absorption.
Reference : Method is specific to the particular instrument.
General procedure is being selected.
Modifications: None
Date: September 1968
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