Aug-31-99 O5:33P P.O1
Method 1001:
Lead in Drinking Water by
Differential Pulse Anodic Stripping
Voltammetry
August 1999
PALIN J KS Y LTD
21 Kculon Lands Road
I'OKnv 18395
Krlangcr
Kentucky 4101X
606/341 -7423
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Acknowledgements
This mcthnd was prepared by Valerie A Argent of Palintest Ltd.
The method was developcd by E D’Costa and S Birch
of Environied plc and i M Southall and V A Argent of Palintest Ltd.
Disclaimer
The nientioui of tiade names or coiiintercial products d0e5 not cc,nstitutc
endorccuiicnt or recommendation fur usc
U
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M ’shod 1001
I ntrod ucti on
Method 1001 was dcvclopcd by PaIint st Ltd and Enviromcd plc to provide a simpic, rapid, low-
cost procedure for the determination of lead in dnnking water
Method 1001 is a performance-based method applicabic to the determination of dissolved lead
and total recoverable lead in drinking water Acid prcscrvcd or acid digested watcr samples are
buffered, and analyzed by diffcrcntial pulse anodic stripping voltammctry (DPASV) using prc-
calibrated disposable sensors
Copcs of thc method can be obtained from, or qucstions conccrning this method or its
application should be addressed to
Vaicric A Argcnc
Palintcst I .td
21 Kcnton Lands Road
P0 Box 18395
Erlaiigei
Kentucky 4 1018
606/341-7423
iii
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Method 1(Y)!
Method 1001
Lead in Drinking Water by
Differential Pulse Anodic Stripping Voltammetry
1.0 Scope and Application
1.1 This method is for the determrnation of dissolved lead and total recoverable lead in drinking waler.
1.2 Although this method has been approved for use in the Environmcntal Protection Agency’s data gathering
and monitoring programs under the Safe Drinking Water Act, it is prudent to check with the appropriate
authority e.g.. the Code of Federal Rcgulations. to verify current approval status.
1.3 I his mcihod ic for the determination of lead, Chemical Abstracts Service Rcgistry Number 7439-92-I -
1.4 1 his method is applicable to drinking water.
1.5 the method detection limit (MDL) was fbund to be 2 ig/l Icad. Ibis was calculated from analysis of seven
aliquots of deionized water fortified with lead stock standard solutiofl to S ag1L lead. The minimum level
(ML) has been set at 5 ig/L.
1.6 ike application range is 2 - 100 ig/L lead Higher concentrations may be determined by samplc dilution
provided that the analyst denionstratcs that the performance of the method can be maintained with the
accepted criteria.
1.7 This method is pcrformancc.based. The laboratory is permitted to omit any step or modify any procedure
(c g ,to overcome interferences, to lower the cost of mcasurementS). provided that all perforrnancc
requirements set forth in this method arc met. The laboratory is not allowed to omit any quality control
analyses. The terms “must”. “may”. and “shouLd” are used in this method to illustrate the importance of tl e
procedures essential in successfully analyzing samples and avoiding contamination; however, these
procedures can be modified or omitted if the laboratory can show that data quality is not affected fhc
requirements lbr establishing method equivaLency are given in Scction 9.1.2.
I .S Any modification of titus method, beyond those expressly permitted, shall be considcrcd a major
modification subject to application and approval of alternate test procedures undcr 40 CFR 136.4 and 136.5
1.9 l ach laboratory that uses this method must demonstrate the ability to generate acceptable results using the
prnccdurc in Section 9 2.
2.0 Summary of Method
2.1 A 25-mL sample is taken and prepared by onC of the following procedures
2.1.1 For dissolved lead, thc sample is filtered to (1 45 im and acidified to p1-1 <2 10 preserve for
trarisp(wtatiOfl
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Meilwd 100/
2.1.2 Ior total recoverable lead, the sample is acidified to p 1- I .2 to preserve for transportation Samples
must be acid digested before analysis
2.2 A SO-mi. aliquol of acid preserved or acid digested sample us neutraliicd with hum hydroxide
2.3 A S-mL portion of the nculrallLcd sample is dccantcd to a sample tube, buffered to p11 4 and condituoumed
with an excess of supporting electrolyte w ensure precision of the analysis. A decon p1cxang dgcnt is added
to release lead from polypliosphate comp1e es.
2.4 The lead in the conditioned sample is dctcrmined by DPASV using a pre-calibrated disposable sensoi. The
lead in the sample is concentrated by plating onto llic working clcctrode of the disposable sensor and then it
is stripped back into solution by raising the electrode potential As the lead teturns to solution a peak of
cwreiu is detected The peak potential identifies the metal and the peak lieu ht is pu pnri tonal in the
conccnlratton of the lead
2.5 the peak height is autoitiatically convem ted to unuerogu ams per I.icr of lead by ref c nc to c il&biation cul es
stored in the unsti tument software The appiopruate alibratioii is selected by keying the eight-digit
calihuatuon code for thc hatch of sensors
2.6 Qii.ility is assured thtroLigli calibration and verification with externally rcl rciiecd statidaid solutions.
3.0 Definitions
I he delinitiojis and purposes below ate specifl in this method, but have been cotilotmed to coun’mmn iisat e
as much as possible
3.1 (.Jnits of weight and measure and their abbreviations
3.1.1 Symbols
C degrees Celsius
less than
percent
I plus or minus
3.1.2 Alphabetical characters
L liter
tug milligram
rng/L milligram per liter
mL milliliter
tg microgram
i&WI. microgram per litet
.tm micrometer
3.2 Detinui’rns, acronyms, and abbieviations
3.2.1 Analytc I he lead tested for by this method
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Me:Iiod 1001
3.2.2 An.tIyiicalh ilch I he ..c of ampIcs acid digested or analyzed at the same time, to a maximum of
20 samples Each analytical batch of 20 or fewer samples must be accompanied by a laboratomy
reagent blank (Section 91.1). an ongoing precision and recovery sample (OPR, Section 9.3.2), and a
matrix ‘pike and matrix spike duplicate (MSIMSD, Scction 9.5), resulting in a minimum of five
utalyses (one sample. one blank, one OPR. one MS and one MSD) and a maximum of 24
analyses (twenty samples, one blank, one OPR. one MS and one MSD) in thc batch. If greater than
20 samples ame to be digested or anolytcd at one time, the samples must be separated into analytical
batches of 20 or fewer samples
3.2.3 Calihr.itinn hlank j3 : A volume of reagent water fortified with the same matrix as the calibration
standards. but without thc anatytcs, internal standards, or surrogate analytes.
3.2.4 CaIiJ r !mgn standard (CAL) ’ A snlutinn prepared from the primary dilution standard solution or
stock standaid solution l’hc C Al.. solutions ate used to calihra1 the instrument response with
mespect to analvie conccntr.itmofl
3.2.5 IWASV The analytical technique of differential pulse anodic stripping voltammeiry
3.2.6 ll’R See initial precision and iccnvcry
3.2.7 Iqitial mrecisiou and rccovem ,(l . Four aliqumots of the diluted PAR analyicd to establish the
ability to gcncratc acceptable precision and accuracy. An JPR is perfonncd the first time this
niethod is used and any time thc method or instrumentation is modified
3.2.fl L j ratory reagent blank (I RB) ’ Au aliquot of reagent water or other blank matrix that isti’eated as
a sample including csposure to all glassware. cquipmcnt, solvents, and rcagcnts that are used with
othem samples [ he l.R13 is used to determine if mcthod analytes or other interferences arc present
iii the laboratory environment, the reagents or ibe apparatus.
3.2.9 Lmneai calibration rarigc (LCR ) The concentration range over which the instrument respon c is
hmneam.
3.2.10 Matrix cpikc (MS) arid _ matri,. spike duplicate (MSDI : Aliquots alan environmental sample to
which known quantities of the analytcs are added in the lab n’atory. The MS and MSD are prepared
and/or analyzed exactly like a field sample. Their purpose is to quantify any additional bias and
imprecision caused by the sample matrix. The back&ound concentration of the anatyte in the
sample matrix must be dctcrrnined in a separate aliquot and the measured values in the MS and
MSD corrected for background concentrations
3.2.11 Material safety d t _ i, Jiect (MSDSI Written information provided for the chemical reagents
conccrning a chemical’s toxicity health hazards, physical properties, fire, and reactivity data
including storage, spill and handling precautions
3.2.1 2 Method detection limit (MDI. ) The minimum concentration ofan analyte that can be identified,
measured, and reported with 99% confidemice that the analyte concentration is greater than zero.
3.2.13 Minimum level (Ml.) : ‘Ike lowest level at which the entire analytical system gives a recognisable
signal and accepiahic calibration point for the analyte. it is equivalent to the concentration of the
lowest calibration standard
3.2.14 y. ‘ [ his action, activity. or procedural step is neither required nor prohibited
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Methcwi 1001
3.2.15 M iy not This action, activity, or procedural step is prohibited.
3.2.16 rvj ,u - This action, activity. or proccdural step is required.
3.2.17 Ongoing. precision and recovery standard (OPR) : An aliquot of reagent watcr or other blank matrix
to which known quantities of the method analyle arc added in the laboratory. The OPR is analyzed
exactly like a sample, and its purpose is to dctcrminc whether the methodology is in control, and
whether the laboratory is capable oF making accurate and precise measurements
3.2.18 Precision and recovery standard (PAR) ’ Secondary standard that is diluted and spiked to form the
IPR and OPR
3.2.19 quality control sampicjQc.Si A solution of method analytes of known concentrations The QCS
i obtained from a cource external to the labotatory or is prcparcd from standards obtained fiont a
different source titan the calibration standards. l’he purpose is to check laboratory performance
uciuig test inaicriak that have been prepared independently from the normal calibration process.
3.2.20 Sliput4 l’liis action, activity. oi piocedurc scp is suggcstcd but not required.
4.0 Interferences
4.1 No interferences have been encountered with the chemical species found naturally in drinking water or
added a treatment chemicals ‘1 he method is without interference for the determination of 2 to 100 igFL
lend in the presence of at least 500 .ig/L aluminium. 1000 ig/L chromium. 1000 .tg/L cadmium, 1000 g/1.
iron, 20() 1 .tgJL manganese. 5000 igJL zinc, 5 mg/L chlorine. 10 mg/L sodium hexametaphosphatc. 10 mg/I
sodium tripolyphosphate. 800 mg/L chloridc. 1 5 mg/L fluoride, 50 mg/L nitrate, 10 rng/L phosphate, 250
mg/i. sulphatc. 500 mg/I. (;a(:o alkalinity. 500 mg/L CaCO3 hardness.
4.2 ‘I he method 1001 iS not appropriate for use on waler samples believed to contain detergent residues, unless
these arc decomposed by acid digestion prior to analysis
4.3 The use of a p11 meter with glass electrode to monitor pH during neutralization of the sample should be
avoided. This causes contamination of the sample and erroneously high results.
5.0 Safety
5.1 Lcad iS a toxic clement, and should be treated as a potential health hazard. Exposure to the standaid
solutions should be reduced to thc lowest possible level, It is suggested that the laboratory perform personal
hygiene monitoring of each analyst using this method and that the results of thiN monitoring be made
available to the analyst
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Method 1001
5.2 this method does not address all safety issues associated with its use. The laboratoiy is responsible for
maintaining a safe working environment and a current awareness file of OSHA regulations regarding the
safe handling of the chemical specified in this method. A rcfcrcnce file of material safety data sheets
(MSDS) should be available to all personnel involvcd in these analyses Additional information on
laboratnry safety can be found in References 16 1 to 16.3.
6.0 Equipment and Supplies
Note: Brand names, suppliers and part numbers are for illu.iirat,ve purposes only. No endorse,nent is implied.
Equivalent performance may be achieved using apparatus and materials other titan those .spccified here. but
demoi:siralion of equivalent performance that meets the requirements of this mci /md is the re.spon,sibiliiy a!
the laboratory.
6.1 Sampling equipment -
6.1.1 Sample collection bottles-glasc. polyethylene or PTIE bottles These inu t be prep ired by tl
method described in Section 6 13 for labware.
6.1.2 Membrane filter assembly and 0.45 pm membrane filters
6.2 Equipment for glassware cleaning:
6.2.1 L.aboriitory smL with ovet head fume hood
(1.3 hquipnierit for sample and standard prcparatiofl
6.3.1 Analytical balance (capabic of weighing 0.1 mg).
6.3.2 Laboratory glassware and plasiicware requircd includes sample containers, volumetric flas1 s 1 pipets.
conical beakers (250-mL), and watch glasses (SO-nun).
6.33 Cleaning.
6.3.3.1 Labwarc should be ihoroug ly washed with laboratory-grade detergent and tap water, rinsed
with tap water then deionized ( Dl) water, rinsed with (1+1) nitric acid, tb n tap water and
finally thoroughly rinsed with D C water
Note: Prolonged soaking of glassware with (1 + 1, nitric acid or chronuc acid should be avoided us this causes ii
lead-demand on glass surfaces.
if ft cart be docwi rented through an active analytical quality control program ?: using jpikcd .samples. reagent
and amnple blanks, that certain steps in the cleaning procedure are no, required for routine samples. I!w.se
1ep.s may he chni,naf d from the procedure.
6.3.4 Laboratory hot plate (capable of maintaining a temperature of 85°C).
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Method 1001
6.4 kquipnwnt for analysis
6.4.1 Diffcrcntial pulse anodic stripping vohammeter dedicatcd to the analysis of lead in drinking water is
required, e
Palintest Scanning Analyzer SA-l000, or
Hack Company I4SA-1000 , or
Pacc Environs Inc PaceScan 1000, or equivalent
6.4.2 Graduated plastic tubes and plastic crushing rods, cleaned as described in Section 6.3.3.
7.0 Reagents and Standards
7.1 Acrd for sample prepauacinn. Because of the high sensitivity of the method ultra high.purity reagents
should be used whenever possibk
7.1.1 Nitric acid, coricentiMed (sp. gr 1 41)
7.1.2 Nitric acid (1 1) Add 500 rn L concentrated nitric acid to 500 mL of Dl water and dii utc to one
liter
7.1.3 Hydrochloric acid, concentrated (sp. gr. 1.19).
7.2 Methyl orange indicator solution 0.1% solution. Dissolve I .Og methyl orangc in 200 inL Dl water and
iii Lc-up to one liter with 1)1 water
7.3 Sodium hydroxide solution 6M Gradually dissolve 240g sodium hydroxidc in 00 mL Dl watcr, stirring
continuously. Allow to cool periodically. Make-up to one liter with Dl water
7.4 Sodium hydro Jdc solution I SM. Gradually dissolve 60g sodium hydroxide in 800 mL D l water, stirring
continuously and allow to cool Make-up to one liter with DI water. (A Neutralization Pack conskting of
I 5M sodium hydroxide solution and methyl orange indicator solution (7.2) is available from Palintest,
Catalogue No PT 429, r Hack Company Cataloguc No 50405-00).
7.5 Sample conditioning tabicts (Soluprep SF-A, Palintest catalogue number PT 425, or Prepi ’ab TM PT-Pb
containcd in sensor pack. Hach Company Catalogue No 50401-00 or equivalent). Tablets contain potassium
phthalatc buffer (p11 4.0) supporling electrolyte and decoinpiexing reagent (trade secret). The nominal
tablct weight is 0.lg arid chclf-life a minimum of five years. The tablets are presented individually
vacuum-sealed in føil packaging for maximum stability.
7.6 Disposable sensOrS (Palintest SE-i. catalogue number PT 425, or uSE-Pb contained in sensor pack, l4ach
Company Catalogue No 50401-00 or equivalent). For the determination of lead and copper in drinking
water. Disposable sensors are manufactured in batches and a carefully selected representative sample of
sensors is withdrawn from across the batch to prepare the calibration curve for the batch, by reference to a
lead standard solution (NIST SRM 3 128) The calibration curve is converted to an eight digit code which is
specific to the batch of sensors To calibrate the instrument for use, this calibration code is keyed in and this
selects the appropriate calibration curve from (lie instrument mcmory. The calibration codc contains chcck
digits to cnsure the instrumcnt rejects erroneously keyed codcs. Disposablc sensors have a shelf lifc of 12
months, and are marked with an expiry date
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M’thod 1001
7.7 Su, .k standard solution (SSS). Prepare a iooa mg/L lead stock standard solution as follows. Accurately
weigh 1.5986g lead (11) ititrate (Pb(NO ) ) and dissolve in apprnxiniately 200 niL Dl WaLCT. Add 10 niL
concentrated nitric acid, mix and dilute to one liter with Dl water. Prepart frcsh every 5i months.
1 OmLSSS 1.0mg Pb
7.7.1 All staiidard solutions prepared from thc stock standard solution should be acidified with 2 n-iL
concentrated nitric acid prior to dilution volume.
7.7.2 Intermediate standard solution (ISS). Daily dilute 10 mL of SSS to a liter with Dl wale,-.
I. O iuL ISS 10 Pb
7.7.3 Working calibration standards are prepared from ISS.
7.7.4 Solulioui bascd oii the SSS are used for prepaiat ion of CAL and MDL.
7.8 lride 1 ,endent standard. Prepare a lead solution by dilution of cnmmei-ciall availahic. NIS I traccahic (i c
tiaceable to a priniaty statidaid) lead nitrate solution rhis standard should he ohtaiiied Ironi a dufkrent
soutrcc than the calibration cijt dards
7.8.! I his solution is used for the preparation of OCS and OPR solutions and to kulily the sample mati i
in the pieparatsout of the MS and MSD
7.9 Deionized watet (E)l) ASTM Type I water or eqitivalein (Reference l(i.4).
8.0 Sample Collection. Preservation and Storage
8.1 Prior to satnpk collection. coiusideratiun should be giveit to the type of data requited so that appioptiate
preserv;ulon and pre.treatinent steps can be taken Filtration, acid preservation 1 etc.. should be porfornied at
the time of sample collection or as soon thereafter as practically possible.
.2 Collect samples in pre-cleaned. acid rinsed. glass, polyethylene, or PTFE bottles
1 .3 I -or the determination of dissolved lead, fultcr the sarnplc through a 0 45-inn inentbrane filtet. Use a
proportion oIthc sample to rinse the filter assembly, discard and then collect the required volunie of tiliraic.
Acidify the filtrate with (1+1) nitric acid immediately following filtration to p11 <2. Normally. 3 ml.. of
(I I I) nitric acid per liter of sample is sufficient.
8.4 For the determination of tota’ recoverable lead 1 acidify with (I + I) nitric acid (3 mL per liter of sample) to
p11 2 The sample may not be filtered prior to analysis.
85 Sarnplc that cannot be acid preserved at thc time of collection, because of sampling limitationc ortran5poul
restriction, hut which must be returned to the laboratory, should be acidified with (1+1) nitric acid to p 1- I <2
on receipt in the laboratory. l-ollowingacidilicatioit, the sample should be held for a minimum of 16 hours
before withdrawing, an liquot for sample processing.
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Mc i&id 100!
9.0 Quality Control
9.1 Each laboratory using this method is required to operate a fonnat quality assurance program (Refercnce
16.5). The minimum requirements of this program consist of au initial demonstration of laboratory
capability, ongomg analyses of standards and blanks as a test of continued performance, and analyses of
matrix spike (MS) and matrix spike duplicate (MSD) samples to assess accuracy and prccusion. Lahorato,-%
performance is compared to establkhed performance criteria to dctcrmine if the results uf analyses niect th
pcrformance characteristics of the method.
9.1.1 The analyst shall make an initial demonstiation of the ability to generate acceptable accuracy and
precision with this method. This ability is established as described in Section 9.2.
9.1.2 In rccognilion of advances that are occurring in analytical technology, the analyst is permitted
certain option ’s In improve or simplify saunpte pre-(reatmcnl or lower then costs of measuictucni ..
provided that all pcrformuncc specifications ate met Altcrnatc dcterminative techniques, such as
visible specirophotomeiry. and changes that degrade method performance. ate not allowed (I’an
analytical technique oilier than the techniques specified in this mcihoct is used, that technique mii t
have a specificity equal to or heiter than the specificity of the techniques iii ilii’, method foi the
analvte of interest Spec ificuty is defined as producing results equivalent to the results piciduiced h%
tins method for analytical standards (Section 9.2.2) and, where applicable, ciivironmenial sauupk’
(Section 93) , and thai mccl 411 of the Q(’ criteria stated in this method
9.1.2.1 Each time a modification is made to this mclhod, the analyst is required to repeat [ lie IPR
test in Section 91 5, to demonstrate that thc modification produces results equivalent to tr
helter than results produced by this method lfthc detection limit of the method will be
afTcctcd by (he modification, the
analyst must demonstrate that the MDL (40 CFR Part 136. Appcndis 13) is lccs than ot t’qu’al
10 !hu MDL for the analyte in this method, or one—third the regulatory compliance level.
whichever is higher If the change will affect calibration, the analyst must recalibi ate the
instrument according to Section 10
9.1.2.2 The laboratory is required toniaintain records of modifications made to this method. 1 lie e
iecords include the following, at a minimum
9.1.2.2.1 The names, titles, addrc scs and telephone numbers of the analyst(s) who
performed the analyses and modification, and of the quality control officci who
witnessed and will verify the analyses and modification.
9.1.2.2.2 Ihe analyte measured, hy name and CASRN
9.1.2.2.3 A narrative stating reason(s) for ihc modification(s).
9.1.2.2.4 Results from all QC lcstS comparing the modified method to this method.
including
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Method 1001
a) Calibration (Section 10)
b) Calibration verification (Section 9.4)
c) Initial precision and rvcovvzy (Section 9.2.5)
d) Analysis of blanks (Section 9.3.1)
c) Accuracy assessment (Section 93)
1) Ongoing precision and recovery (Section 9.32)
9.1.2.2.5 Data that will allow an independent reviewer to validate each dctcrmination by
tracing the instrument output (weight or othcr signal) to the final result. Uhese
data arc to include:
a) Sample numbers and other identifiers
b) Digestion dates
c) Analysis dates and times
d) Analysis scqucncelrun chronology
e) Sample weight or volurite
1) Digest volume
g) Make and modcl of DPASV instrument and standardc traceable to NIST
h) Copies of log hooks. printcr Iapcs and other recordings of raw data.
i) Data system oulpuic. and oilier data to link the raw data to the results
reported
9.1.3 Analyses of laboratory blanks arc required to dcmonstrate freedom from contamination. The
procedure and criteria for analysis of a blank are described in Section 9.3.1.
9.1 .4 I he laboratory shall. on au ongoing basis, demonstrate through calibration verification arid analysis
of tIme OIm oint precision and rccovcry sample that the analysis cystciii is in control I hcsc
procedures are described in Sect ion 9.4 and 9.3.2. respectively.
9.1.5 Analysis of matrix spike and matrix spike duplicate samples are required to demonstrate method
accuracy and precision and to monitor matrix interferences (interferences caused by the sample
matrix). The procedure and OC criteria for spiking are described in SectiQn 9.5.
9.l.(, The laboratory should maintain records to define the quality of the data that is generated.
Development of accuracy statements is described in Sections 9.3.2.3 and 9.5.9.
9.2 Initial demonstration of performance
9.2.1 The initial demonstration of performance is used to characterize instrument performance
(determination of LCRs and analysis of QCS), laboratory performance (determination of MDLs) and
precision and recovery (determination of mean and standard deviation of replicate analyscs) prior to
performing analysis by this mcthod.
9.2.2 Linear calibration range (LCRJ. The LCR must be determined initially and verified every si
months r whenever a significant change in instrument rvsponsc is ob crved or expected. The initial
demonstration of linearity must use a minimum of a calibration blank and three calibration
standards
If any verification data cmiceeds thc initial values by l0%, linearity must be rc.cstablished. If any
portion of the range is shown to be non-Imear, sufficient standards must be used to clearly define the
non-linear portion.
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MeiIwd 100 /
9.2.3 Quality coiniol sampk (QCS) Obtain a standard containing a known concentration of lead from a
commercial source, different from the source of the CAL standards. Prepare a QCS with a
concenlra(urn in the mid-range of the calibration (30 to 70 tgJL lead) by diluting (he standard with
reagent water or blank matrix. The QCS must be analyzed when beginning to use the method, on a
quarterly basis, or as required to meet data-quality needs, and verify (lie calibration standards and
acceptable instrument perfonnance If the determined concentrations are not within ± 10% of the
stated values, performance of the method is unacceptable. Ihc source of the problem must be
identified and corrected before either proceeding with the initial determination of MDLs or
Continuing with on-going analyses.
9.2.4 Method detection limit (MDL). MDl..s must hc established for all analyses, using reagent Water
tortified at a concentration of one to fivc times the estimated instrument detection limit (Reference
16 6) To determine MDL values, take seven replicate aliquots of the fortified reagent water and
process through the entire analytical method Perform all calculations defined in the method and
lepoil the concentration values in the appropriate units Calculate the Ml) !. as follci s
Ml)l = (I) s (s)
Whece t — Suidetit’s ‘I value for a 99 °/u confidence level and a standard deviation estimate with
n-I degrees of freedom It 3 14 for seven leplicatesi.
= tai dard (leviilI ton of the replicate analyses
ML)1.s cliould he determined every sb months, when a new operator begins work, or whenever theie
is a significant cllaiI e iii the background or instrument response
9.2.5 luiti l precision and recovery (percent recovery) To establish the ability to generate acceptable
precision and accuracy, the analyst should perfonu the following opemat ions
9.2.5.1 Prepate a pieciston and recovery standard (PAR) by fortifying an LRH with QCS solution to
a Icad concentration of 30 to 70 pg/L Pb. Analyze four aliquots of the PAR according to the
procedure in Scction I I 0
9.2.5.2 Calculate the percent recovery of the added analyte lot each observation, using (he
following equation
Equanon I
R — _______ x 100
S
it ’);ere R = Pcrc ’iil rrcovery (9’o,)
C. Fortified blank concelurozion (pg/Li
C LR.B background cnncc’uraiion (jigiL)
= Concei,irui.on equivak’nz of analyte added 10 the F.M /I (gg/L)
9.2.5.3 thing the results of the set of four analyses, compute the average percent recovery (X) and
the standard deviation of the pcrc.cnl recoveries (s). Use the Ibllowir ig equation for
calculation of’ the standard deviation of the percent recovery -
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Methud /001
Eqiwlion 2
I ( ‘ \
r L ____
where ,a nw,ther of samples
R, -- percL’nI recc’ i’c’rv in och sample (Reference It,. 6)
9.2.5.4 Compare s and X with the corresponding limits for initial precision and recovery in Sectucin
I 7A) (Table I) Ifs and X niect ihc acceptanec criteria, sy4cm performance is acceptable
and analysis of samples may begun If, however. s cxcceds the precision limit or X f tIk
outside the range for recovery. s stem performance is unacceptabk. In this event. correct
the problem and repeat the tcst
9.3 As t ssing continuing laboratory performance
9.3.1 Laboratory reagent blank (LRD). The laboratory must analyze at least one LRB with each analylical
batch to demonstrate freedom from contamination. Perform a laboratory i-eagent blaiil by
substituting Dl water for the sample and carrying out the
fbll analytical procedure as described in Section 11.0. Data pioduced is used to asscsc
contamination from the laboratory environment. Values that exceed the minimum lcvcl (Section
1 6) indicate that laboratory Or rcagcnt contamination should be suspcctcd Analysts of samples is
halted until the source of oontamninaüon is eliminated and a blank shows no evidence of
contamination. All sample must be associated with an uncontaminated method blank before the
results may be reported for regulatory compliance purposes.
9.3.2 Ongoing precision and recovery (OPR). To demonstrate that the analysis systcm is in control, and
ucccptablc precision and accuracy is being maintained, the laboratory must analyze at least one PAR
with each batch of samples The lead concentration of the PAR should be in the mid-range of the
calibration (30 to 70 igfL lead).
93.2.1 Calculate accuracy as percent recovery (Scction 9.2.5 2) II the recoYery of the analyte falls
outside thc r quircd cuntrul limits of 80 to 120%, the analytical process is not in control. In
this event, identify and correct the problem before repeating the OI’R and analysis ot ’ the
sample batch
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Mci/god 1001
9.3.2.2 Development of criteria for evaluation of ongoing precision and recovery. Whcn sufficient
internal perforrmrncc data is available (at least 20 to 30 analyses) optional control limits can
be developed from ‘X’. the avcragc pcrcent recovery, and ‘s’., the standard deviation of the
individual percent recoveries. The data can bc u5ed to establish the upper and lower control
limits as follows
Upper control limit = X 4 3s
Lower control limit X - 3s
The opticrnal control limits must be equal to or better than the required control limits of 80
to l20°h
9.3.2.3 The laboratory should add rcsults that pass the specification in Section 9.3.2.1 to l R and
previous OPR data and update QC charts to form a graphic rcpre cl1Iatiun of continued
laboratory performance. The laboratory should also develop a statement of laboratory dala
quality from X and s, expressing the accuracy as a recovery inteival from X - 2s to X i Zs
9 4 Calibration veiificalion. The laboratory must aitalyze at least one QCS and calibtatuon blank daily to erifS
ihe calibration (Scclion 923). Ifihedetennined conccntratio,i i not within ± 10% of calibration, reanalyLe
the OCS lithe second analysis confirms the calibration is outside the limits, halt sample ana1ysm and
determine the cause. In the case of drift, recalibrate the instruments. All samples f llowing the lai.t
acceptable QCS must be reanalyzed. The analysis data of the QCS and calibration blank must bc kept cm
file with the sample analyses data.
9.5 Assessing analyte recovery and data quality matrix spikes.
1 lic laboratory must cpikc, in duplicatc. a minimum of 10 pcrceIlt 0 f all sallipleb from a given sampling site
1 he two sample aliquots .hall he spiked with lead solution (Section 7.8.!).
9.5.1 The spiking level shall be high enough to be detected above the original sample and should not be
less than four times the MDL. It should, preferably, be one to five times the action level for lead (I
Lwl ).
9.5.2 Using the indcpendcnt lead standard, prepare the spiking solution of 5000 pg/L lead. Using a
I 00-mL aliquot of sample, I .0-mL of spiking solution fortifies the sample by 50 ig/L lead
9.5.3 Analyze one sample aliquot according to the proccdurc in Section I 1 to determine the background
concentration of lead (C).
9.5.4 Spike two further sample aliquots (MS and MSD) with the spiking solution and ana1y c thcsc
aliquots to determine the concentration after spiking (C 1 ). using the proccdure in Section II.
9.5.5 Calculate the percent recovery, R, of lead in each aliquot using the following equation:
12 August/99
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ALJg—31 .-99 05:37P P.16
Mt’!h(,d 1001
Equai:oii 3
lOO(C,-C)
8=
T
where.
F l = Percent recovery
= Mea3ure Conccntrdllion of analyic after . p:kmg
C = Measured backgi owid cunce,n’raiwn
T True concenirouon of the spike
9.5.6 Compare the percent recovery with the cot responding QC acceptance criteria in Section Ii 0 ( lable
I)
9.5.6.1 If the recovery of the spike fails the acceptable criteria, and the recovery 01 the QC taiidaid
in the OPR test (Section 9.3 2) for the analytical batch k within the acceptahic criteria in
Table 1, an interference is present. If the interference is aflribuiahlc L sampling, the site
should be resampled. It the intcrfercncc is attrihutablc to method deficiency, the analyst
must modify the method, repeat the tests required in Section 9.1 .2, and repeat the analysis of
the sample and the MS/MSD
9.5.6.2 If the results of both the spike and the OPR fail the acceptance criteria, the analytical cysicili
is judgcd to he out of control, and the problem shall he idcntiuicd and corrected, and the
sample rcanaly,ed
9.S.7 Computc thc rclativc pcrccnt difference (RPD) bctwccn the two results (not between the two
rccovcrics) using the following equation
quaiioi. 4
R.PD = - x 100
0.5 (f.) + J )
where
1), = Mea tire CQiTCCfllrU(iCifl t ’ f lead in cthqziol one (MS)
= Measured c’oncenn-atlon of/cad in aliquor two (MS’Q)
9.5.8 The relative percent difference for duplicates shall meet the acceptance criteria in 1 ablc I - If the
criteria arc not mc i, the analytical system is judged to be out of control, arid the problem i iust be
immediately identified and corrected, and (lie analytical batch reanalyzed.
13 Augus t/ )9
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Method 1001
9 5.9 As part of the QC program for the laboratory, mcthod precision and accuracy for samples should be
assessed and records should be maintained. After the analysis of five spiked samples in which the
recovery passes the test in Section 9.5.6. compute the average percent recovery (Pa) and the standard
dcviation of the percent recovery (s,). Express the accuracy assessment as a perecnt recovery
interval from Pa - 2s to Pa + 2s Update the accuracy assessmcnt on a regular basis (e.g. after cadt
five to ten new accuracy measurements)
9.6 The specifications coniamed in this method can be met if the apparatus used is scrupulously cleaned The
standards used for initial precision and recovciy (IPR Section 9.2.5), ongoing precision and recovery (OPR
Section 9 3.2). and matrix spikes (MS/MSD Section 9.5). should bc identical, so that the most precise results
will be obtained.
9.7 Depending upon specific piograrn requirements, field replicates and field spikes of the analytes of iittcrcst
,,ito samples may he required to assess the precision and accuracy of the sampUng and sample Iransporling
techniques.
10.0 Calibration and Standardization
10.1 Pi eparc a serii s of at least threc CA Ls and a CR covering the ties ircd cnnccntral u n range. by di lutiu
suitable volumes of ISS (7 7 I) with D I water
10.2 Process CALs and Cl3s as described in Sei.tion ILO. Proccdurc
10.3 h rcparc a standard curve by plotting instrumcnt response against concent,-ation values The calibration
curve may be derived using manual plotting or computer- or calcuiator-ha cd regression urvc fitting
techniques
10.4 Alter the calibration has been established, it should be verified with a ACS as described in Sectio,i 9.4.
10.5 Calibration standards shall hc within * 10% at IS pg/Land 60 pg/I_. If the calibration standards are not
within these limits, consult the equipment manufacturer.
11.0 PROCEDURE
11.1 Preparation of standard solution. Neutralize to above pH 4.0 with a minimum volume of sodium
hydroxide Take 50-mL of standard in a sample container, add two drops of methyl orange indicatoi
solution (Section 7 2) and add I SM sodium hydroxide solution dropwise until the colour changes from pink
to yellow. Analyic the ncutralii.cd standard immediately
11.2 Sample preparation for dissolved lead. Neutralize the filtrate to above p11 4.0 with a minimum volume of
sodium hydroxide. Take 50-inL of sample in a sample container, add two drops of niethyl orange indicator
solution (Section 7 2) and add I .5M sodium hydroxide solutinn drop wisc until the colour changes from pink
to ycllow Analyze the neutralized sample immediately.
Note: The use of a pH meter to monitor the neutralization process has been found to i,,troduce uiwcceplable /evclc
of contanunalion.
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Method 1001
11.3 Sample preparation for total recoverable lead. Acid digestion must be carricd out. 1 akc a I OO-mL (
I -mL) aliquoc from a well-mixed, acid preserved sample and transfer it to a 250-mL conical beaker. Add I
ml. of concentrated nitric acid and 0.5 mL of concentrated hydrochloric acid. 1-Icat tile sample on a hot plate
at 85°C until the volume has been rcduced to approximately 20 mL, ensuring that the sample does not boil.
Note: Fvr proper healing, adjust the temperature control of the hot plate such I/sa l an wicovered beaker
containmg 50 ‘siL of kvier located in i/se center of the hot plale can be maintained at approximaic’Iy . but ,ig,
higher th ,, 85°C Evaporation linse for (00 niL ofsanip/e a: 85°C is approximately two hour. wit/s the’ rate
ofrvaporation rapidly increasing ii f/ic sample volume appmaches 20 niL.
Ciwer the beaker with a watch glass and reflux for 30 minutes. Slight boiling may occur but vigorous
boiling should be avoided. Allow to cool and quantitatively transfer to a 100-mi. volumetric flasL l)ilute to
volumc with Dl water aitd mi
Neutralize the acid digest to above pH 4 0. with a minimum voittune olsodium hydroxide solution. 1 tke 50
mL dt ested sample in a cample containe,. add two drops ol methyl otange indicator solutiøn (Scetion 72)
.iiid .udd 6 tiM sodium hydroxide oluition drop wise until the color chauigcs from punk to yellow. Aualv,c
the neutral I7cd sample imined iately
11.4 Di pcn’ c S ml. of prepared sample to the 5-,iil. plastic lube provided and proceed iimtieduateiy
11.5 Add one Conditioning tablet (Section 73) to ihc 5 mL of sample. Crush tablet with a crusl ,n rod arid iiii
Lu dISSOlvc Eiistirc the tablet is compktciy dissnlvcd.
11.6 Place the insijuinent on a clean, dry surface, iii an environment free horn dust, draughts, and vibration,
within tile temperature range 20 to 25 ’C. Insert the tube of piepared sample into the test ILub e holder.
11.7 Press the ‘ON’ key the insirunlent display shows the calibration code Compare this number itli the ccdc
on the sensor packaging Prec ‘EN IER’ to accept, or key in the correct code and press ‘ENTER’
Note: (‘k’ck th(’ expiry dale on the .se,r. vr packaging Do not use expireö’ sensors
11.8 The instrument proceeds with an atitoniatic system and battery check, and will not allow analysis unless
these are satisfactory
11.9 At the screen prompt ‘Insert electrode and immerse’ take one disposable sensor (Scelion 7.6) and open the
toil strip. Incert (lie sensor tracks into the connector cap and immerse the sensor into the sample. I)o not
disturb the instrumcnt or sample during the test.
11.10 The instrument senses the sample and automatically begins the analysis. After three minutes the results
appear on-screen as a dircci reading
11.11 Depress the button on the connector cap to eject the used sensor.
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Method 100/
Note: 7 / ic ,nsirw,,e,, 1 is programmed to recognize a iumber of user errors, such a. used or con:aniina,ed se?m sr
poor electrical connection or failure to add conditioning lab/el The instrument will abort the lest and
display au error me. sage. I i is isnportanl to keep the con ,,ector cap clean and dry Is, avoud repeated error
nie . sage.c due 10 we! or dirty electrical contacts
12.0 Data Analysis and Calculations
12.1 II a sample dilution has bccn used. multiply the answer by the appmpriatc dilution factor
Etjuaiio’i )
Total Volunu’
D,lill,oii Facwr — - -
•‘ca, ip/e l’oluine
•So, ip/r Volunyc’ — A liquot ofsaniple taken for dilu: ion (n2L)
Two! Volume Volume to which saiiiple volwiur i.c diluted (sn 4)
(or, cc/ed (‘oncc’nlr(,1, on = Ob.scrvcd concentralion x dilution ra
12.2 Rc io,iing
12.21 Repori resulic in micrograms pcr liter ( ig/L Pb).
12.2.2 Kepori results to two significant figures above 10 tg/L. Report results to one significant flgiirc
hclow 10 gl(-
12.23 Report results below the ML. as less than the ML (Section 1.5).
13.0 Method Performance
13.1 Using thc Palintcst Scanning Analyzer SA-l000. the standard deviation of replicate observations (1% — 10) of
a calibration standard containing I S iglL lead was 0 75 ig/L.
13.2 With multiple batches of tablet reagents and sensors, the relative standard deviation of sets of observations
(n — IC)) of a calibration standard containing 15 jsg/L lead varied from 2.1 to 3.8%.
13.3 A sun lc laboratory reported the analysis of seven aliquoisofa drinking water sample, initially containing 8
p JL kdd, but fortified to a total lead concentrdtion of 48 jig/L The mean percent recovery of the added 40
)u /L lead was 110% and the corresponding standaid deviation of the percent recovcrks was 1.5%
14.0 Pollution Prevention
14.1 The quantity of chemical purchased should be based on expected usage during its shelf.lifc and disposal co%t
of unused material.
- 16 August/99
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Mi’,/i,xj /1)0!
14.2 Standards should be prepared in volumes conci ctcnI itli laboratory use to minimize the volume of c pirecJ
standards to he disposed
15.0 Waste Management
15.1 ft is the laboratory’s responsibility to oinpIy with all federal, statc, and focal tegulations governing waste
management, particularly the h.iLardouS waste identification rules and land disposal resti ictions, and to
protect the air, water, and land by minimi/ing and controlling au releases from fume hoods and bench
operations. Compliance with all sewage discharge penmis and regulaiions is also required
15.2 l-.xcess reagents, sainpks and method process wastes should be characterized and disposed of in an
acccptable manner The MSI)S sheet gives details of product composition and rutay be coiisuilted for
guiidauice on wafle disposal
15.3 Sarnpks preserved wuh nitric ,lLId to pH 2 are hazardous aitd must be nculrali,cd hemote beun disposed, or
ilutust he handled ;u haza, douic
15.4 Stauidards contaunuulg lead Iflus be h.indI d as lia,ardciui waste
I 5.5 I or lijuiher tubs mat ion on ‘.tsie uu mugcntcnt, ecrnsuult Thi Watei Manageinciil Manual for l.ahurainr
Pcu soituiel”. and ‘l.css us Rettei Laboeauoiy ,Cheuiical \ianagciucni for Wasie Reduction”, both asailabic
from the America , ’ cheni ca I Society’s Oepai tunen( of Gover,iunciit Relations and Science Pol ic , I 1 55 I bLIi
Street N W, Wasl un tuii DC. 20(136
16.0 References
l( . I “Carcunogeiis-Workxug W i uilt ( aicinogens”. Qeparirneiti off lenlth, Education, and Vlelfare. l’ublie Health
Service. Center fot Disease _ontrol. National Institute for Occupational Safety and health, Publication ? u
77.206, August 1977
16.2 “OSHA Safety and Health Stauidards,Gciierallndustr ”.(29CFR 1910), Occupational Saicty and Health
Administration, OSHA 2206 (Revised, January 1976)
16.3 “Safely in Academic Chemistry Laboratories”. American Chemical Society, Committee on Chemical Satety.
3rd Edition, 1979
16.4 1)1 193-91 Standaid Specification for Reagent Water Annual Hook of’ AS I M Standards. Volume I I .01.
Pit iladclphia PA American Society of Testing Materials 1993
16.5 “Handbook of Analytical QtiaIur Control in Water and Wastewacer Laboratories”, USEPA, EMSL-Ci,
Cincinnati. OIl 45268, L PA -600/4 -79-0I9, March 1979.
16.6 Code of Federal Regulations. Title 40, Part 136, Appendix H
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McfIu)(/ /00/
17.0 Tables and Graphs
17.1 1 jbIe J Acceptance Criteria for Performance Tests
Acceptance Criterion Section Limit (%)
lmtral precision and recovery
Prec suon (s) 9.2 5.4 5
Recovcry (X) 9.2.54 80-120
( )n jnunt precision and recovery
Recoverv(X) 932.1 80-120
( al uhrai ion ‘eriruc;it ion
QCSRCCO%er) 9.4 90-HO
Malrup!kc!matri.\ .pikc diiplicalc
Recovery 9.5.6 80-120
Precision (iclatuve perceni ditterence) 9 i 20
17.2 (;raph I Example calibration graph
Calibration Graph - Lead
120
_ioo y096O x -
R’09999 --
80
C
0 -
60
40
2
In
20
-- .---—..---- . . -
0 20 40 60 80 100 120
Calibration standard (PbI gIL)
1 8 Augiisi/99
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