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Example Chemistry Measurement Uncertainty Calculations V3 Corrected 031312

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Contributors to Uncertainty Representative and Applicable QC Data Transportation/Storage/Handling: shipping time, container and temperature NA / (FS) lab storage time, conditions and temperature NA / (LCS, FS) contamination in lab storage areas NA / LCS, FB Laboratory Subsampling  sample nonhomogeneity DUP blending techniques DUP sample size DUP Sample Preparation: volumetric glassware LCS, DUP dispensing device LCS, DUP balance LCS, DUP temperature LCS, DUP sample extraction LCS, DUP extractant background LCS, DUP, MB Lab Environmental Conditions: temperature variance LCS, DUP humidity variance LCS, DUP Analysts: different analysts LCS, DUP analyst training level and experience LCS, DUP data interpretation by analyst LCS, DUP Measuring Instruments: instrument stability LCS, DUP carry over effects LCS, DUP Common Contributors to M (representative list - ma (QC sample types in this list are typical of those u addition
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    Contributors to Uncertainty

    Representative

    and ApplicableQC Data

    Transportation/Storage/Handling:

    shipping time, container and temperature NA / (FS)

    lab storage time, conditions and temperature NA / (LCS, FS)

    contamination in lab storage areas NA / LCS, FB

    Laboratory Subsampling

    sample nonhomogeneity DUPblending techniques DUP

    sample size DUPSample Preparation:

    volumetric glassware LCS, DUPdispensing device LCS, DUP

    balance LCS, DUPtemperature LCS, DUP

    sample extraction LCS, DUPextractant background LCS, DUP, MB

    Lab Environmental Conditions:

    temperature variance LCS, DUPhumidity variance LCS, DUP

    Analysts:

    different analysts LCS, DUPanalyst training level and experience LCS, DUP

    data interpretation by analyst LCS, DUPMeasuring Instruments:

    instrument stability LCS, DUP

    carry over effects LCS, DUP

    Common Contributors to M(representative list - ma

    (QC sample types in this list are typical of those u

    addition

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    day to day calibration differences LCSinterferences LCS

    Calibration Standards/Reference

    Materials:

    preparation variances LCS

    calibration stock material uncertainty CERTIFICATE

    LCS reference material uncertainty CERTIFICATETest Procedure Variations:

    variation within and between reagent lots LCSextraction or digestion times, temperatures,

    and conditions LCSsample dependent modifications LCS

    desorption efficiencies within and between

    lots for sorbents LCSData Manipulation:

    sampling media/blank correction LCS, MBinstrument blank correction LCS

    accuracy of calculations LCS

    area or air volume sampled NA

    Where:

    DUP = Duplicate, resulting from sub-sampling of a bul

    NA = Not Applicable

    FB = Field Blank

    FS = Field Spike - Not typically conducted unless part

    is responsible for field sampling.

    LCS = Laboratory Control Standard, matrix matched a

    batch

    MB = Method or Matrix Blank

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    Comments to Clarify Contributor Effects

    NOTE: This is not part of analytical uncertainty, but must be considered by labs

    providing sampling and when providing guidance regarding sample packaging and

    shipping. Usually no impact if recommended shipping conditions and holding times in

    referenced methods are maintained. Improper packing materials, bulks shipped w/samples,

    etc. may adversely affect data. Field blanks, field spiked samples or duplicate field samples

    shipped with samples or included in method validation studies may reflect these contributors.

    Field variability (FS/DUP) is only considered when lab is responsible for sampling.

    Usually no impact if recommended storage conditions and holding times in reference

    methods are maintained.Impact is monitored per sample batch only if LCS samples are

    prepared on receipt and stored with field samples. Field spiked samples or stability study

    samples included in some method validation studies may also reflect these contributors. Field

    variability (FS/DUP) is only considered when lab is responsible for sampling.

    Usually no impact if recommended storage conditions and holding times in reference

    methods are maintained. Improper storage such as sorbent tubes stored with bulk solvent

    samples or near solvent sources may adversely affect data. Impact is monitored only if LCS

    is prepared on receipt & stored with field samples. Field blank can be used to assess

    contamination from collection, transport, and storage.

    NOTE:This primarily applies to bulk/solid samples which requires use of laboratory duplicate

    sample data to determine impact on uncertainty. It is not applicable for LCS/LCSD media

    spike duplicates.

    Sample composition, etc.

    Stirring, sieving, grinding, etc.

    Large enough to allow adequate subsampling.

    NA for Class A; applies for graduated tubes or cylinders, etc.

    Pipettes, and other types of dispensers that are not Class A.

    Balance error is often insignificant compared to other MU sources.

    Hot plate or ashing temperatures.

    Applies to LCS or DUP if it goes throughthe entire sample preparation process.

    Analyte or interferant is present in acids, solvents, etc.

    Room temp during bulk asbestos, gravimetry, etc. processes.

    Gravimetry involving hydroscopic media, etc.

    Must use inter-analyst instead of intra-analyst repeat data, where applicable.

    Must use inter-analyst instead of intra-analyst repeat data, where applicable.

    Chromatographic peak ID, interference corrections, etc. Must use inter-analyst instead of

    intra-analyst repeat data, where applicable.

    Baseline drift, repeatability of averaged readings, lab environmental stability, etc.

    Impact of high samples on following sample readings; can be monitored by proper use of

    CCBs.

    asurement Uncertainty Chemical Analyses not be all inclusive for all types of analyses)

    tilized in AIHA-LAP, LLC laboratories) See

    l tabbed sheets for examples

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    Variation in instrument response and calibration process

    Due to matrix, inter-element effects, co-eluting GC peaks, etc.

    Due to analysts, balances, dispensing devices used, etc

    Obtain from certificate or estimate, can be ignored if less than 1/3 of the largest contributor.Only has impact when LCS data are used to correct customer sample results. Obtain from

    certificate or estimate. Can be ignored if less than 1/3 of the largest contributor. Note that

    use of an LCS with a large uncertainty can result in over estimation of overall analytical

    uncertainty.

    Similar to extractant background effects under Sample Preparation above.

    May affect complete dissolution of analyte or loss of material in some cases.

    Changes in conditions due to sample size, customer requests, etc.

    May vary by lot or manufacturer; also applies to diffusion rates for passive monitors.

    When significant and when data are blank corrected.

    When allowed.

    Manual, spreadsheet, LIMS, etc.

    Typically provided by the customer. This is not part of analytical uncertainty, but must be

    considered by labs providing sampling and providing combined sampling and analytical

    uncertainty.

    k (NOTE: NOT LCS/LCSD duplicate spiked sampling media)

    of sampling method validation. Should be considered only when laboratory

    nd typically taken through the entire analytical process with each sample

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    Contributors to UncertaintyRepresentative andApplicable QC Data Comments to Clarify Contributor Effects

    Transportation/Storage/Handling

    shipping time, container & temperature NA Limited impact on most sorbent tubes

    lab storage time, conditions & temperature NA

    Usually no impact if recommended storage conditions and hold times are

    samples are representative if prepared on receipt & stored with field sampl

    impact if recommended storage conditions and holding times are maintain

    samples or stability study samples included in some method validation stud

    these contributors.

    contamination in lab storage areas NAUsually no impact if appropriate storage conditions are maintained. Field

    assess contamination from collection, transport, and storage

    Laboratory Subsampling sample nonhomogeneity NA Not applicable to sorbent tube analysis

    blending techniques NA Not applicable to sorbent tube analysis

    sample size NA Not applicable to sorbent tube analysis

    Sample Preparation:

    volumetric glassware LCS Same type of glassware used for samples and LCS

    dispensing device LCS Same type of dispensing device

    balance NA Not applicable to sorbent tube analysis

    temperature NA Not applicable to sorbent tube analysis

    sample extraction LCS Applies to LCS if goes through sample preparation

    extractant background LCS, MB Analyte or interferant in solvents or other prep reagents used, etc.

    Lab Environmental Conditions:

    temperature variance LCS LCS results reflect any temperature effects on chromatography instrumenhumidity variance NA Not applicable to sorbent tube analysis

    Analysts:

    different analysts LCS LCS results reflect variability due to different analysts, as applicable, on dif

    analyst training level & experience LCS LCS results reflect variability due to different analysts, as applicable, on dif

    data interpretation by analyst LCS LCS results reflect variability due to different analysts, as applicable, on dif

    Measuring Instruments:

    instrument stability LCS LCS results reflect instrument variability on different days

    carry over effects LCS LCS results reflect instrument variability on different days

    day to day calibration differences LCS LCS results reflect instrument variability on different days

    interferences LCS LCS results reflect instrument variability on different days

    Calibration Standards/Reference Materials:

    preparation variances LCS Due to analysts, dispensing devices used, etc

    calibration stock material uncertainty CERTIFICATE Obtain from certificate or estimate

    LCS reference material uncertainty CERTIFICATEUse if customer sample data corrected for desorption efficiency. Obtain fr

    estimate.

    Test Procedure Variations

    variation within and between reagent lots LCS LCS subjected to same treatment as customer samples

    extraction or digestion times and temps

    LCSLCS subjected to same treatment as customer samples

    sample dependent modifications LCS LCS subjected to same treatment as customer samples

    desorption efficiencies within and between lots

    for sorbent tubes LCS LCS subjected to same treatment as customer samples

    Chemical Analyses of Sorbent Tubes using Chromatography

    See Example Calculations (to the right of the table)

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    for sorbent tubes LCS LCS subjected to same treatment as customer samples

    LCS = Laboratory Control Standard, typically taken through the entire analytical process with each sample batch

    MB = Method or matrix blank

    NA = Not Applicable

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    LCS mg LCS %Rec LCSD mg

    LCSD

    %Rec LCS mg LCS %Rec LCSD mg LCSD %Rec

    0.0876 101.0 0.0884 102.0 0.0862 106.4 0.0832 96.0

    0.0824 95.0 0.0850 98.0 0.0799 98.6 0.0812 93.7

    0.0867 100.0 0.0858 99.0 0.0839 103.6 0.0825 95.2

    0.0832 96.0 0.0841 97.0 0.0923 114.0 0.0874 100.8

    0.0789 91.0 0.0789 91.0 0.0847 104.6 0.0819 94.5

    0.0798 92.0 0.0806 93.0 0.0702 86.7 0.0907 104.6

    0.0850 98.0 0.0850 98.0 0.0632 78.0 0.0676 78.0

    0.0824 95.0 0.0867 100.0 0.0933 115.2 0.0870 100.30.0858 99.0 0.0867 100.0 0.1005 124.1 0.0924 106.6

    0.0850 98.0 0.0850 98.0 0.0987 121.9 0.0933 107.6

    0.0876 101.0 0.0858 99.0 0.0826 102.0 0.0919 106.0

    0.0832 96.0 0.0884 102.0 0.0913 112.7 0.0756 87.2

    0.0884 102.0 0.0919 106.0 0.0770 95.1 0.0920 106.1

    0.0867 100.0 0.0893 103.0 0.0910 112.3 0.0960 110.7

    0.0902 104.0 0.0884 102.0 0.0832 102.7 0.0928 107.0

    0.0850 98.0 0.0876 101.0 0.0984 121.5 0.0884 102.0

    0.0876 101.0 0.0902 104.0 0.0872 107.7 0.0861 99.3

    0.0834 96.2 0.0892 102.9 0.0809 99.9 0.0655 75.5

    0.0819 94.5 0.0812 93.7 0.0926 114.3 0.0956 110.3

    0.0797 91.9 0.0784 90.4 0.0979 120.9 0.0889 102.5

    98.2 103.1

    4.0 11.5

    RSD 4.05% RSD 11.2%

    8.1% % 22.3% %

    Bias @ 103.1% Rec = 3.1%

    No significant background in method blank. No significant background in method blank.

    40 point Mean % Rec 40 point Mean % Rec

    Example of reporting for 0.085 mg n=butanol: 0.0butanol with an analytical uncertainty of +/- 0.019

    95% confidence level with probable bias of 0.003

    Reference material used for calibration indicates assay

    of 99.5%. Expanded uncertainty of reference material

    estimated at 0.5% (95%) Divide by 2 to yield 0.25 % Rel.

    SD. Insignificant compared to 4.0% can be eliminated

    from calculation

    Reference materials used for calibration and LCS

    preparation indicate assay of 99.5%. Expanded un

    of reference materials estimated at 0.5% (95%). Di

    to yield 0.25 % Rel. SD. Insignificant compared to

    can be eliminated from calculation

    Example of reporting for 0.085 mg toluene:0.085 mg toluene with an analytical uncertainty of +/-

    0.007 mg at the 95% confidence level with probable bias

    of -0.002 mg

    mg Toluene on Charcoal Tube using CS2Desorption per NIOSH 1501

    LCS/LCSD = 0.0867 mg toluene spike/tube

    Expanded MU @

    95% Conf k=2

    Bias @ 98.2% Rec = -1.8%

    Examples of Analytical Measurement Uncertainty for Analysis of Organic Solvents on Charcoal Tubes

    mg n-Butanol on Charcoal Tube using CS2Desorption per NIOSH 1401Mod

    LCS/LCSD = 0.0810 mg n-butanol spike /tube

    (includes correction for DE = 0.80)

    40 point Std Dev 40 point Std Dev

    Expanded MU @

    95% Conf k=2

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    5 mg n- g at the

    g

    certainty

    ide by 2

    11.2%

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    Contributors to Uncertainty

    Representative

    and Applicable

    QC Data

    Transportation/Storage/Handling

    shipping time, container & temperature NAlab storage time, conditions & temperature NA

    contamination in lab storage areas NALaboratory Subsampling

    sample nonhomogeneity DUPblending techniques DUP

    sample size DUPSample Preparation:

    volumetric glassware LCS, DUPdispensing device LCS, DUP

    balance LCS, DUPtemperature LCS, DUP

    sample extraction LCS, DUPextractant background LCS, DUP, MB

    Lab Environmental Conditions:

    temperature variance NAhumidity variance NA

    Analysts:

    different analysts LCS, DUPanalyst training level & experience LCS, DUP

    data interpretation by analyst LCS, DUPMeasuring Instruments:

    instrument stability LCS

    carry over effects LCS, DUPday to day calibration differences LCS

    interferences DUP, MS

    Calibration Standards/Reference Materials:

    preparation variances LCS, DUP

    calibration stock material uncertainty CERTIFICATELCS reference material uncertainty NA

    Test Procedure Variations

    variation within and between reagent lots LCS

    extraction or digestion times and temps LCS

    sample dependent modifications LCS

    Example of Contributor

    Chemical Analyses of L

    See Example Calculat

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    desorption efficiencies within and between lots for

    sorbent tubes NAData Manipulation:

    sampling media blank correction NAinstrument blank correction

    LCS

    Accuracy of calculations LCS

    DUP = Duplicate, resulting from sub-sampling of a bulk (N

    MB = Method or matrix blankNA = Not Applicable

    FB = Field Blank

    FS = Field Spike

    LCS = Laboratory Control Standard, matrix matched and t

    sample batch

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    Comments to Clarify Contributor Effects

    No impact on bulk paint samples from transportation, storage or normal handling

    LCS

    mg/Kg

    True

    value

    mg/Kg

    195.4 208.8

    189.6 208.8

    4157 4490Sample composition, etc. 4186 4490Stirring, sieving, grinding, etc 184 208.8Large enough to allow adequate subsampling 184 208.8

    4641 4490NA for Class A; applies for graduated tubes or cylinders, etc. 4831 4490pipettes, and other types of dispensers not Class A 179 208.8balance error is often insignificant compared to other MU sources 177 208.8Hot plate or ashing temperatures 4539 4490

    Applies to LCS or DUP if goes through sample preparation 4858 4490Analyte or interferant in acids, or other reagents 198 208.8

    207 208.8No impact on bulk paint samples 4458 4490No impact on bulk paint samples 4514 4490

    Analyst contributors affect all aspects of analysis from subsampling through data

    manipulation 184 208.8

    187 208.8

    4551 4490

    4580 4490

    179 208.8Baseline drift, repeatability of averaged readings, etc 186 208.8Impact of high samples on following sample readings; can be monitored by proper

    use of CCBs 4245 4490

    4302 4490Due to matrix, inter-element effects, etc. Cannot be routinely determined for

    typical industrial hygiene sampling media 188 208.8

    202 208.8Due to analysts, balances, dispensing devices used, etc 4217 4490

    Obtain from certificate or estimate 4300 4490Sample results not corrected for LCS recovery 203 208.8

    190 208.8

    Similar to extractant background effects under Sample Preparation above 30 point Mean % Rec.

    May affect complete dissolution of analyte or loss of material in some cases

    Changes in conditions due to sample size, customer requests, etc RSD

    30 point Std Dev

    s to Measurement Uncertainty

    ad (Pb) in Paint using ICP-AES

    ons (to the right of the table)

    Examp

    Pb in Paint using hotblock acid

    Analysis in accordance with EP

    (Mod)

    LCS Recovery of Paint SRM 258

    or SRM 2581 at 4490 +/

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    No sampling media with bulk samples

    when allowed

    Manual, spreadsheet, LIMS, etc

    OTE: NOT LCS/LCSD duplicate spiked sampling media)

    ypically taken through the entire analytical process, with each

    Example o

    4400 mg/K

    confidenc

    Example a

    Expanded

    Bias = 440

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    LCS % Rec

    mg/Kg

    Sample

    mg/Kg

    Sple Dup

    Std Dev

    (S) CV CV2

    93.6 1604 1502 72.12 0.0464 0.0022

    90.8 511 602 64.35 0.1156 0.0134

    92.6 9470 8794 478.00 0.0523 0.0027

    93.2 161 93 48.08 0.3786 0.1433

    88.1 1683 1411 192.33 0.1243 0.0155

    88.1 956 830 89.10 0.0998 0.0100

    103.4 23470 26570 2192.03 0.0876 0.0077

    107.6 625 730 74.25 0.1096 0.0120

    85.7 723 472 177.48 0.2970 0.0882

    84.8 23000 22000 707.11 0.0314 0.0010

    101.1 14190 13900 205.06 0.0146 0.0002

    108.2 10350 9142 854.18 0.0876 0.0077

    94.8 5702 5854 107.48 0.0186 0.0003

    99.1 109 122 9.19 0.0796 0.0063

    99.3 7079 6427 461.03 0.0683 0.0047

    100.5 196 186 7.07 0.0370 0.0014

    88.1 14510 14300 148.49 0.0103 0.0001

    89.6 15710 17150 1018.23 0.0620 0.0038

    101.4 1187 1192 3.54 0.0030 0.0000

    102.0 9265 9246 13.44 0.0015 0.0000

    85.7 4240 3918 227.69 0.0558 0.0031

    89.1 1979 1574 286.38 0.1612 0.0260

    94.5 2357 3068 502.75 0.1853 0.0344

    95.8 2254 3062 571.34 0.2150 0.0462

    90.0 53160 44300 6264.97 0.1286 0.0165

    96.7 24810 23000 1279.86 0.0535 0.0029

    93.9 22860 22930 49.50 0.0022 0.0000

    95.8 1133 1125 5.66 0.0050 0.000097.2 151 96 38.89 0.3149 0.0992

    91.0 7774 4366 2409.82 0.3970 0.1576

    94.7 CV 0.7064

    6.3 CV pooled = (CV2/30) = 0.1534 15.3%

    6.7%

    Sample duplicata data in mg/Kg for Pb in Paint using

    hotblock acid digestion and ICP-AES in accordance with

    EPA SW-846 3050 & 6010 (Mod)

    les of Analytical Measurement Uncertainty for Lead in Paint

    digestion and ICP-AES

    SW846 3050 & 6010

    2 at 208.8 +/- 4.9 mg/Kg

    110 mg/Kg Pb

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    Combined Rel. Std Dev (SDc) = [ SD12+ SD22]

    SDc = [(6.7)2+ (15.3)2] = 16.7%

    33.4%

    f reporting for 4400 mg/Kg Pb in paint:

    g Pb in paint with an analytical uncertainty of +/- 1500 mg/Kg at the 95%

    level and a probable bias of -230 mg/Kg

    nalytical uncertainty for 4400 mg/Kg Pb in paint sample:

    analytical uncertainty of 4400 mg/Kg Pb in paint = 4400 X0.334= 1470 mg/kg

    mg/kg X -0.053 = 233.2 mg/kg

    Bias @ 94.7% Rec of LCS = -5.3%

    Reference material used for calibration indicates concentration and expanded

    uncertainty of 1001 +/- 5 ug/mL at 95% confidence level. Expanded uncertainty

    divided by 2 to yield 0.25 % Rel. SD. Insignificant compared to 15.2% and can

    be eliminated from calculation. No significant background in

    method blank.

    Expanded MU @ 95% Conf (k=2) =

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    RSD


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