NISTIR 7880-5 

NIST Micronutrients Measurement 

Quality Assurance Program 

Winter 2010 

Comparability Studies 

Results for Round Robin LXVII 

Fat-Soluble Vitamins and Carotenoids in Human Serum 

and Round Robin 32 Ascorbic Acid in Human Serum 

David L. Duewer 

Jeanice B. Thomas 

 

 

 

 

NISTIR 7880-5
 

NIST Micronutrients Measurement 

Quality Assurance Program 

Winter 2010 

Comparability Studies 

Results for Round Robin LXVII 

Fat-Soluble Vitamins and Carotenoids in Human Serum 

and Round Robin 32 Ascorbic Acid in Human Serum 

David L. Duewer 

Jeanice B. Thomas 

Chemical Sciences Division 

Materials Measurement Laboratory 

April, 2013 

U.S. Department of Commerce 

Rebecca Blank, Acting Secretary 

National Institute of Standards and Technology 

Patrick D. Gallagher, Under Secretary of Commerce for Standards and Technology and Director 
(This page intentionally blank) 

ii
 
 

 

Abstract 

The National Institute of Standards and Technology coordinates the Micronutrients Measurement 

Quality Assurance Program (MMQAP) for laboratories that measure fat- and water-soluble vitamins 

and carotenoids in human serum and plasma. This report describes the design of and results for the 

Winter 2010 MMQAP measurement comparability improvement studies: 1) Round Robin LXVII 

Fat-Soluble Vitamins and Carotenoids in Human Serum and 2) Round Robin 32 Total Ascorbic Acid 

in Human Serum. The materials for both studies were shipped to participants in December 2009; 

participants were requested to provide their measurement results by March 8, 2010. 

Keywords 

Human Serum
 

Retinol, α-Tocopherol, γ-Tocopherol, Total and Trans-β-Carotene
 

SRM 968e
 

Total Ascorbic Acid
 

iii 
 

 

 

 

 

 

 

Table of Contents 

Abstract............................................................................................................................................... iii
 

Keywords ............................................................................................................................................ iii
 

Table of Contents ............................................................................................................................... iv
 

Introduction......................................................................................................................................... 1
 

Round Robin LXVII: Fat-Soluble Vitamins and Carotenoids in Human Serum ....................... 1
 

Round Robin 32: Vitamin C in Human Serum............................................................................... 2
 

References ............................................................................................................................................ 3
 

Appendix A. Shipping Package Inserts for RR67........................................................................ A1
 

Appendix B. Final Report for RR67 ..............................................................................................B1
 

Appendix C. “All-Lab Report” for RR67 ......................................................................................C1
 

Appendix D. Representative “Individualized Report” for RR67 ............................................... D1
 

Appendix E. Shipping Package Inserts for RR32 ......................................................................... E1
 

Appendix F. Final Report for RR32............................................................................................... F1
 

Appendix G. “All-Lab Report” for RR32..................................................................................... G1
 

Appendix H. Representative “Individualized Report” for RR32............................................... H1
 

iv 
 

 

Introduction 

Beginning in 1988, the National Institute of Standards and Technology (NIST) has coordinated the 

Micronutrients Measurement Quality Assurance Program (MMQAP) for laboratories that measure 

fat- and water-soluble vitamins and carotenoids in human serum and plasma. The MMQAP 

provides participants with measurement comparability assessment through use of interlaboratory 

studies, Standard Reference Materials (SRMs) and control materials, and methods development and 

validation. Serum-based samples with assigned values for the target analytes (retinol, alphatocopherol, gamma/beta-tocopherol, trans- and total beta-carotene, and total ascorbic acid) and 

performance-evaluation standards are distributed by NIST to laboratories for analysis. 

Participants use the methodology of their choice to determine analyte content in the control and 

study materials. Participants provide their data to NIST, where it is compiled and evaluated for 

trueness relative to the NIST value, within-laboratory precision, and concordance within the 

participant community. NIST provides the participants with a technical summary report concerning 

their performance for each exercise and suggestions for methods development and refinement. 

Participants who have concerns regarding their laboratory’s performance are encouraged to consult 

with the MMQAP coordinators. 

All MMQAP interlaboratory studies consist of individual units of batch-prepared samples that are 

distributed to each participant. For historical reasons these studies are referred to as “Round 

Robins”. The MMQAP program and the nature of its studies are described elsewhere. [1,2] 

Round Robin LXVII: Fat-Soluble Vitamins and Carotenoids in Human Serum 

Participants in the MMQAP Fat-Soluble Vitamins and Carotenoids in Human Serum Round Robin 

LXVII comparability study (hereafter referred to as RR67) received one lyophilized and four liquidfrozen human serum test samples for analysis. Unless multiple vials were previously requested, 

participants received one vial of each serum. These sera were shipped on dry ice to participants in 

December 2009. The communication materials included in the sample shipment are provided in 

Appendix A. 

Participants are requested to report values for all fat-soluble vitamin-related analytes that are of 

interest to their organizations. Not all participants report values for the target analytes, and many 

participants report values for non-target analytes. 

The final report delivered to every participant in RR67 consists of three documents: 

•	 A cover letter for the current study, a brief description of the other two documents, and a 

discussion of our analysis of the overall results that may be of broad interest. This cover 

letter is reproduced as Appendix B. 

•	 The “All-Lab Report” that lists all of the reported measurement results, a number of 

consensus statistics for analytes reported by more than one participant, and the mean median 

and pooled SD from any prior distributions of the serum. This report also provides a 

numerical “score card” for each participant’s measurement comparability for the more 

commonly reported analytes. This report is reproduced as Appendix C. 

1
 
 

 

•	 An “Individualized Report” that graphically analyzes each participant’s results for all 

analytes reported by at least five participants. This report also provides a graphical summary 

of their measurement comparability. The graphical tools used in this report are described in 

detail elsewhere [3]. An example “Individualized Report” is reproduced as Appendix D. 

Round Robin 32: Vitamin C in Human Serum 

Participants in the MMQAP Vitamin C in Human Serum Round Robin 32 comparability study 

(hereafter referred to as RR32) received four frozen serum test samples, one frozen control serum, 

and a solid ascorbic acid control material for analysis. Unless multiple vials were previously 

requested, participants received one vial of each material. These sample materials were shipped on 

dry ice to participants in December 2009. The communication materials included in the sample 

shipment are provided in Appendix E. 

The test and control serum materials were prepared by adding equal volumes of 10 % 

metaphosphoric acid (MPA) to human serum that had been spiked with ascorbic acid. While these 

samples contain some dehydroascorbic acid, its content is variable. Therefore, the participants 

report only total ascorbic acid (TAA, ascorbic acid plus dehydroascorbic acid). Participants are also 

encouraged to prepare calibration solutions from the supplied solid control to enable calibrating their 

serum measurements to the same reference standard. 

The final report delivered to every participant in RR32 consists of three documents: 

•	 A cover letter for the current study, a brief description of the other two documents, and a 

discussion of our analysis of overall results that may be of broad interest. This cover letter is 

reproduced as Appendix F. 

•	 The “All-Lab Report” that summarizes all of the reported measurement results and provides 

several consensus statistics. This report is reproduced as Appendix G. 

•	 An “Individualized Report” that graphically analyzes each participant’s results for TAA, 

including a graphical summary of their measurement comparability. The graphical tools 

used in this report are described in detail elsewhere [3]. An example “Individualized Report” 

is reproduced as Appendix H. 

2
 
 

References 

1 Duewer DL, Brown Thomas J, Kline MC, MacCrehan WA, Schaffer R, Sharpless KE, May WE, 

Crowell JA. NIST/NCI Micronutrients Measurement Quality Assurance Program: Measurement 

Repeatabilities and Reproducibilities for Fat-Soluble Vitamin-Related Compounds in Human 

Sera. Anal Chem 1997;69(7):1406-1413. 

2 Margolis SA, Duewer DL. Measurement Of Ascorbic Acid in Human Plasma and Serum: 

Stability, Intralaboratory Repeatability, and Interlaboratory Reproducibility. Clin Chem 

1996;42(8):1257-1262. 

3 Duewer DL, Kline MC, Sharpless KE, Brown Thomas J, Gary KT, Sowell AL. Micronutrients 

Measurement Quality Assurance Program: Helping Participants Use Interlaboratory Comparison 

Exercise Results to Improve Their Long-Term Measurement Performance. Anal Chem 

1999;71(9):1870-1878. 

3
 
Appendix A. Shipping Package Inserts for RR67 

The following three items were included in each package shipped to an RR67 participant: 

• Cover letter 

• Datasheet 

• Packing List and Shipment Receipt Confirmation Form 

The cover letter and datasheet were enclosed in a sealed waterproof bag along with the 

samples themselves. The packing list was placed at the top of the shipping box, between 

the cardboard covering and the foam insulation. 

A1
December 7, 2009 

Dear Colleague: 

UNITED STATES DEPARTMENT OF COMMERCE 

National Institute of Standards and Technology 

Gaithersburg, Maryland 20899-

Enclosed are samples for the first fat-soluble vitamins and carotenoids in serum study (Round Robin 

LXVII) for the 2010 NIST Micronutrients Measurement Quality Assurance Program. The set of samples 

(Sera 362 - 366) consists of one lyophilized sample and one vial each of four liquid-frozen serum samples 

for analysis along with a form for reporting your results. These samples should be stored in the dark at or 

below -20 °C upon receipt. When reporting your results, please submit one value for each analyte for a 

given serum sample. If a value obtained is below your limit of quantification, please indicate this result 

on the form by using NQ (Not Quantified). Results are due to NIST by March 8, 2010. Results received 

more than two weeks after the due date may not be included in the summary report for this round robin 

study. The feedback report concerning the study will be distributed in April 2010. 

Samples should be allowed to stand at room temperature under subdued light until thawed. We 

recommend that sample mixing be facilitated with 3 to 5 min agitation in an ultrasonic bath or at least 15 

min at room temperature with intermittent swirling. (CAUTION: Vigorous shaking will cause foaming 

and possibly interfere with accurate measurement. The rubber stopper contains phthalate esters that may 

leach into the sample upon intermittent contact of the liquid sample with the stopper. These esters absorb 

strongly in the UV region and elute near retinal in most LC systems creating analytical problems.) 

Water should not be added to the liquid-frozen samples. Add water (1 mL) only to the lyophilized 

serum #362. 

For consistency, we request that laboratories use the following absorptivities (dL/g ·cm): retinal, 1843 at 

325 nm (ethanol); retinyl palmitate, 975 at 325 nm (ethanol); cx-tocopherol, 75.8 at 292 nm (ethanol); ytocopherol, 91.4 at 298 nm (ethanol); ex-carotene, 2800 at 444 nm (hexane); ~-carotene, 2560 at 450 nm 

(ethanol), 2592 at 452 nm (hexane); and lycopene, 3450 at 472 nm (hexane). 

Please report your results for Round Robin LXVII by e-mail to david.duewer@nist.gov or fax to 301-

977-0685. If you have questions or comments regarding this study, please call me at (301) 975-3120 oremail me atjbthomas@nist.gov. · 

nalytical Chemistry Division 

Chemical Science and Technology Laboratory 

Enclosures 

NISI 

A2
 

 

 

Participant #: ________ Date: _____________ 

Round Robin LXVII: Human Sera 

NIST Micronutrients Measurement Quality Assurance Program 

Analyte 362 363 364 365 366 Units* 

total retinol 

trans-retinol 

didehydroretinol 

retinyl palmitate 

α-tocopherol 

γ/β-tocopherol 

δ-tocopherol 

total β-carotene 

trans-β-carotene 

total cis-β-carotene 

total α-carotene 

total lycopene 

trans-lycopene 

total β-cryptoxanthin 

total α-cryptoxanthin 

total lutein 

total zeaxanthin 

total lutein&zeaxanthin

 total coenzyme Q10 

ubiquinol (QH2) 

ubiquinone (Qox) 

phylloquinone (K1) 

25-hydroxyvitamin D 

Other measurands? 

* we prefer μg/mL 

Were the liquid-frozen samples (363 to 366) frozen when received? Yes | No 

Comments: 

Mail: M2QAP Please return results by 

NIST, Stop 8392 8-Mar-2010 Fax: 301-977-0685 

Gaithersburg, MD 20899-8392 Email: David.Duewer@NIST.gov 

A3
 

 

 

 

Participant #: ________ Date: _____________ 

Fat-Soluble Vitamins Round Robin LXVII
 

NIST Micronutrients Measurement Quality Assurance Program
 

Packing List and Shipment Receipt Confirmation Form 

This box contains: one vial each of the following five FSV M2QAP sera 

Serum Form Reconstitute? Vial/Cap 

#362 Lyophilized Yes 2 mL clear or amber, blue cap 

#363 Liquid frozen No 2 mL amber, green cap 

#364 Liquid frozen No 2 mL amber, metallic-blue cap 

#365 Liquid frozen No 2 mL amber, red cap 

#366 Liquid frozen No 2 mL amber, silver cap 

Please 1) Open the pack immediately 

2) Check that it contains all of the above samples 

3) Check if the vials are intact 

4) Store the sera at -20  ̊C or below until analysis 

5) Complete the following information 

6) Fax the completed form to us at 301-977-0685 

(or email requested information to david.duewer@nist.gov) 

1) Date this shipment arrived: ___________________________ 

2) Are all five sera vials intact? Yes | No 

If "No", which one(s) were damaged? 

3) Was there any dry-ice left in cooler? Yes | No 

4) Did the liquid frozen samples (#363 to #366) arrive frozen? Yes | No 

5) At what temperature are you storing the serum samples? _______  ̊C 

6) When do you anticipate analyzing these samples? ________________________ 

Your prompt return of this information is appreciated. 

The M2QAP Gang 

Mail: M2QAP 

NIST, Stop 8392 Fax: 301-977-0685 

Gaithersburg, MD 20899-8392 Email: David.Duewer@NIST.gov 

A4
 

 

 

Appendix B. Final Report for RR67 

The following two pages are the final report as provided to all participants: 

•	 Cover letter. 

•	 An information sheet that: 

o	 describes the contents of the “All-Lab” report, 

o	 describes the content of the “Individualized” report, 

o	 describes the nature of the test samples and details their previous distributions, 

if any, and 

o	 summarizes aspects of the study that we believe may be of interest to the 

participants. 

B1
April 27, 201 O 

Dear Colleague: 

UNITED STATES DEPARTMENT OF COMMERCE 

National Institute of Standards and Technology 

G~ithersburg, Maryland 20899-

Enclosed is the summary report of the resi,ilts for round robin LXVII (RR67) of the 2010 NIST 

Micronutrients Measurement Quality Assurance Program (M2

QAP) fo~ the fat-soluble vitamins and 

carotenoids in human serum. Included in this report are: 1) a summary of data and measurement 

comparability scores for all laboratories, 2) a detailed graphical analysis of your results; and 3) a 

graphical summary of your measurement comparability. 

Your overall measurement comparability is summarized in the "Score Card" summary, page 6 of the All 

Lab Report. Combined results rated 1to3 are within 1to3 standard deviations of the assigned value, 

respectively; those rated 4 are >3 standard deviations from the assigned value. Similar information is 

presented graphically in the "target plots" that are the last page of your Individualized Report. If you 

have concerns regarding your laboratory's performance, please contact us for consultation . 

. Samples for the second 2010 QA interlaboratocy exercise will be shipped during the week of June 7, 

2010. If you have any questions regarding this report, pleas~ contact Dave Duewer at 

david.duewer@nist.gov or me atjbthomas@nist.gov, tel: 301/975-3120, or fax: 301/977-0685. 

eanice Brown Thomas 

Research Chemist 

Analytical Chemistry Division 

Chemical Science and Technology La~oratory 

Cc: L.C. Sander 

David L. Duewer, Ph.D. 

Research Chemometrician 

Analytical Chemistry Division 

Chemical Science and Technology Laboratory 

NlSI 

B2
 

 

 

 

 

 

 

 

The NIST M2QAP Round Robin LXVII (RR67) report consists of: 

Page 

1-4 A listing of all results and statistics for all analytes. 

5 A legend for the list of results and statistics. 

6 The text Comparability Summary (“Score Card”) of measurement performance. 

Page “Individualized” Report 

1 

2 to 

n 

n+1 

Samples. 

Serum 

362 

363 

364 

365 

366 

Results 

“All Lab” Report 

Your values, the number of labs reporting values, and our assigned values. 

“Four Plot” summaries of your current and past measurement performance, one page for 

each analyte you report that is also reported by at least 8 other participants. 

The graphical Comparability Summary (target plot) of measurement performance. 

Five samples were distributed in RR67. 

Description 

Lyophilized, native, single-donor, commercially 

obtained serum prepared in 2002. The same 

material was used to prepare #366. 

Fresh-frozen, native, multi-donor, prepared in 2009. 

This is Level III of candidate SRM 968e. 

Fresh-frozen, native, multi-donor, prepared in 2009. 

This is Level II of candidate SRM 968e. 

Fresh-frozen, native, multi-donor, prepared in 2009. 

This is Level I of candidate SRM 968e. 

Fresh-frozen, native, single-donor, commercially 

obtained serum prepared in 2002. The same 

material was used to prepare #362. 

Prior Distributions 

#290:RR53-2/03, #300:RR55-3/04, 

#312:RR57-3/05, #322:RR59-3/06, 

#333:RR61-3/07, #348:RR64-9/08 

#359:RR66 – 9/09 

#358:RR66 – 9/09 

#357:RR66 - 9/09 

#292:RR53-2/03, #301:RR55-3/04, 

#313:RR57-3/05, #323:RR59-3/06, 

#332:RR61-3/07, #349:RR64-9/08 

1)	 Candidate SRM 968e. Sera #363 to #365 are the components of candidate SRM 968e. All three 

materials were distributed last Fall in RR66; there have been no significant changes in the level nor 

variability of any of the reported analytes. 

These materials were prepared by blending commercially available materials without spiking. The 

materials were designed to represent relatively low, middle, and high levels of retinol, α-tocopherol 

and β-carotene. We will notify you when SRM 968e material becomes available for purchase. 

2)	 Sera 362 and 366. These materials were prepared in 2003 from the same serum pool to help evaluate 

the commutability and relative stability of lyophilized and fresh-frozen sera. There have been no 

significant changes in the relative levels of any of the reported analytes. However, there is some 

evidence for increased variability of lutein and zeaxanthin in both materials. 

B3
 

 

Appendix C. “All-Lab Report” for RR67 

The following six pages are the “All-Lab Report” as provided to all participants, with two 

exceptions: 

• the participant identifiers (Lab) have been altered. 

• the order in which the participant results are listed has been altered. 

The data summary in the “All-Lab Report” has been altered to ensure confidentiality of 

identification codes assigned to laboratories. 

Sera 363, 364, and 365 are the components of the candidate NIST SRM 968e FatSoluable Vitamins, Carotenoids, and Cholesterol in Human Serum. Summary results for 

the NIST analysis of these materials are listed in the “All-Lab Report.” These NIST 

results are not used in the assessment of the consensus results of the study. 

C1
Round Robin LXVII Laboratory Results 

Total Retinol, μg/mL trans-Retinol, μg/mL Retinyl Palmitate, μg/mL α-Tocopherol, μg/mL γ/β-Tocopherol, μg/mL 

Lab 362 363 364 365 366 

C2

FSV-BA 0.616 0.665 0.517 0.366 0.645 

FSV-BB 0.602 0.640 0.517 0.342 0.616 

FSV-BC 0.579 0.627 0.495 0.349 0.639 

FSV-BD 0.613 0.653 0.530 0.359 0.640 

FSV-BE 0.661 0.723 0.560 0.400 0.725 

FSV-BF 0.650 0.680 0.530 0.360 0.650 

FSV-BG 0.610 0.659 0.521 0.376 0.649 

FSV-BH 0.603 0.607 0.455 0.329 0.617 

FSV-BJ 0.571 0.611 0.480 0.352 0.615 

FSV-BK 0.555 0.581 0.436 0.281 0.570 

FSV-BL 0.630 0.660 0.520 0.340 0.630 

FSV-BM 0.620 0.690 0.560 0.410 0.670 

FSV-BN 0.590 0.662 0.519 0.360 0.676 

FSV-BNa 0.582 0.643 0.497 0.354 0.638 

FSV-BO 0.547 0.571 0.451 0.300 0.575 

FSV-BP 0.630 0.650 0.520 0.370 0.660 

FSV-BQ 0.864 0.917 0.711 0.500 0.918 

≥0.590 ≥0.750 ≥0.490 ≥0.390 ≥0.590 FSV-BR 

≥0.616 ≥0.687 ≥0.566 ≥0.416 ≥0.710 FSV-BS 

FSV-BT 0.627 0.601 0.482 0.325 0.550 

FSV-BU 0.731 0.653 0.461 0.334 0.579 

FSV-BV 0.646 0.612 0.523 0.381 0.676 

FSV-BW 0.615 0.653 0.501 0.345 0.632 

FSV-CC 0.825 0.692 0.519 0.385 0.709 

FSV-CD 0.520 0.510 0.400 0.390 0.400 

FSV-CE 0.668 0.654 0.517 0.368 0.707 

FSV-CF 0.591 0.722 0.496 0.364 0.616 

FSV-CG 0.534 0.612 0.512 0.356 0.584 

FSV-CI 0.645 0.712 0.547 0.391 0.677 

FSV-CW 0.686 0.587 0.482 0.364 0.631 

FSV-CZ 0.598 0.640 0.520 0.364 0.627 

FSV-DA 0.557 0.641 0.481 0.338 0.605 

FSV-DD 0.650 0.570 0.430 0.300 0.550 

FSV-DI 0.690 0.720 0.580 0.400 0.700 

FSV-DV 0.528 0.562 0.437 0.287 0.547 

FSV-EE 0.561 0.649 0.536 0.376 0.593 

≥0.527 ≥0.522 ≥0.416 ≥0.347 ≥0.504 FSV-EZ 

362 363 364 365 366 

0.590 0.750 0.490 0.390 0.590 

0.616 0.687 0.566 0.416 0.710 

0.800 0.692 0.511 0.365 0.692 

0.557 0.641 0.481 0.338 0.605 

0.527 0.522 0.416 0.347 0.504 

362 363 364 365 366 

0.107 0.163 0.071 0.022 0.115 

0.071 0.074 0.022 0.013 0.075 

0.101 0.179 0.054 0.017 0.103 

0.076 0.074 nq nq 0.075 

0.091 0.094 0.023 nd 0.100 

0.110 0.110 0.020 ≤0.01 0.110 

0.094 0.093 0.035 0.013 0.097 

0.055 0.047 0.015 0.007 0.058 

0.077 0.070 0.018 0.007 0.096 

0.080 0.070 0.015 0.010 0.085 

0.073 0.070 nq nq 0.070 

362 363 364 365 366 

9.75 18.30 9.99 6.46 10.20 

10.30 18.40 10.40 7.13 10.90 

10.50 19.30 11.40 7.90 11.50 

9.50 18.17 9.96 6.38 10.25 

9.80 17.80 9.70 6.50 10.00 

10.09 19.24 10.59 6.86 10.91 

9.49 18.03 9.88 6.31 10.01 

9.35 18.06 10.48 6.43 9.86 

9.37 18.51 9.50 5.86 9.62 

10.40 18.60 10.80 7.00 10.90 

9.70 18.80 10.70 6.90 10.20 

10.90 21.57 11.66 7.44 12.08 

10.28 20.60 10.96 6.88 11.39 

9.70 17.50 9.70 6.30 9.90 

8.56 18.51 9.60 6.48 9.86 

13.20 24.30 13.00 8.90 13.60 

11.54 22.80 9.64 6.83 11.33 

10.81 17.88 9.76 6.43 10.28 

10.70 19.76 9.71 5.62 7.80 

9.81 16.83 10.51 6.93 11.15 

9.50 18.22 9.83 6.30 9.96 

11.90 19.06 9.65 6.84 11.10 

9.67 17.32 9.79 8.23 8.24 

9.82 22.31 9.69 6.76 11.70 

11.10 17.90 10.70 6.40 9.90 

8.31 16.68 9.85 6.06 9.26 

9.94 20.03 11.18 7.46 11.26 

10.52 20.87 11.79 7.84 12.03 

9.13 15.47 6.86 4.42 7.20 

9.77 19.31 10.00 6.63 10.66 

10.80 19.60 11.20 7.10 10.90 

4.40 13.60 5.20 3.70 6.90 

10.40 18.60 9.60 6.70 10.90 

9.59 16.92 9.53 7.48 9.47 

362 363 364 365 36

1.90 2.54 1.54 1.95 1.9

1.78 2.34 1.48 1.86 1.8

1.69 2.32 1.41 1.76 1.8

1.80 2.40 1.50 1.97 1.9

1.70 2.29 1.40 1.77 1.8

1.57 2.12 1.38 1.78 1.6

1.60 2.00 1.30 1.60 1.7

1.93 2.31 1.38 1.77 1.7

2.10 2.34 1.49 1.93 2.2

1.48 1.78 1.24 1.60 1.6

1.63 2.15 1.32 1.69 1.6

1.66 2.02 1.28 1.70 1.6

1.62 2.31 1.53 1.83 1.8

1.66 2.26 1.44 1.96 1.8

2.21 3.01 1.88 2.40 2.4

1.70 2.22 1.40 1.69 1.7

1.73 2.50 1.41 1.90 1.9

1.91 2.48 1.58 2.01 1.9

1.68 2.26 1.41 2.12 1.7

N 34 34 34 34 34 5 5 5 5 5 11 11 9 7 11 34 34 34 34 34 19 19 19 19 1

Min 0.520 0.510 0.400 0.281 0.400 0.527 0.522 0.416 0.338 0.504 0.055 0.047 0.015 0.007 0.058 4.40 13.60 5.20 3.70 6.90 1.48 1.78 1.24 1.60 1.6

Median 0.614 0.650 0.517 0.360 0.632 0.590 0.687 0.490 0.365 0.605 0.080 0.074 0.022 0.013 0.096 9.82 18.51 9.92 6.73 10.27 1.70 2.31 1.41 1.83 1.8

Max 0.864 0.917 0.711 0.500 0.918 0.800 0.750 0.566 0.416 0.710 0.110 0.179 0.071 0.022 0.115 13.20 24.30 13.00 8.90 13.60 2.21 3.01 1.88 2.40 2.4

SD 0.053 0.056 0.032 0.028 0.057 0.049 0.069 0.031 0.038 0.129 0.016 0.029 0.010 0.006 0.021 0.71 1.18 0.60 0.53 0.96 0.12 0.14 0.12 0.18 0.1

CV 9 9 6 8 9 8 10 6 10 21 20 39 47 49 22 7 6 6 8 9 7 6 9 10 

Npast 33 33 33 33 33 8 5 5 5 8 11 12 9 11 11 35 34 34 34 35 21 21 21 21 2

Medianpast 0.610 0.654 0.497 0.351 0.642 0.611 0.549 0.471 0.330 0.644 0.092 0.090 0.021 0.008 0.097 9.93 18.48 10.30 6.75 10.46 1.74 2.08 1.34 1.72 1.8

SDpast 0.045 0.052 0.049 0.033 0.047 0.037 0.102 0.064 0.032 0.048 0.019 0.020 0.005 0.005 0.021 0.71 1.39 0.86 0.52 0.65 0.14 0.38 0.16 0.18 0.1

11 11 11 11 11 11 11 11 11
 

MeanNIST
 

NNIST 

0.657 0.490 0.346 19.52 10.25 6.96 2.30 1.49 2.03 

0.017 0.011 0.013 0.41 0.17 0.40 0.16 0.08 0.10 Srep 

0.000 0.003 0.009 0.13 0.11 0.00 0.00 0.00 0.00 Shet 

0.017 0.011 0.016 0.44 0.20 0.40 0.16 0.08 0.10
 

NAV
 

SNIST 

0.614 0.653 0.504 0.353 0.632 0.590 0.687 0.490 0.365 0.605 0.080 0.074 0.022 0.013 0.096 9.82 19.01 10.09 6.84 10.27 1.70 2.30 1.45 1.93 1.8

NAU 0.053 0.056 0.046 0.031 0.057 0.049 0.069 0.039 0.038 0.129 0.022 0.029 0.012 0.011 0.025 0.77 1.61 0.81 0.59 0.96 0.18 0.23 0.17 0.24 0.1

All Lab R eport 
 

Round Robin LXVII Laboratory Results 

Total β-Carotene, μg/mL trans-β-Carotene, μg/mL Total cis-β-Carotene, μg/mL Total α-Carotene, μg/mL Total Lycopene, μg/m

C3

Lab 362 363 364 365 366 362 363 364 365 366 362 363 364 365 366 362 363 364 365 366 362 363 364 365 

FSV-BA 0.117 0.395 0.246 0.091 0.118 0.105 0.374 0.232 0.079 0.108 0.012 0.021 0.014 0.012 0.010 0.063 0.014 0.030 0.008 0.065 0.536 0.939 0.657 0.201 

FSV-BB 0.090 0.285 0.159 0.065 0.100 0.086 0.276 0.151 0.063 0.092 0.005 0.009 0.008 0.002 0.008 0.057 0.005 0.017 0.002 0.062 0.394 0.733 0.433 0.187 

FSV-BC 

FSV-BD 

FSV-BE 0.106 0.414 0.243 0.086 0.117
 

FSV-BF
 0.103 0.370 0.213 0.087 0.093 

FSV-BG 0.143 0.460 0.262 0.101 0.148 0.079 0.021 0.033 0.009 0.082 0.521 0.954 0.585 0.216 

FSV-BH 0.108 0.410 0.245 0.080 0.116 0.108 0.396 0.235 0.080 0.116 nq 0.014 0.010 nq nq 0.072 nq nq nq 0.078 0.520 1.079 0.674 0.241 

FSV-BJ
 0.127 0.416 0.218 0.097 0.113 0.090 0.032 0.052 nq 0.094 0.539 1.133 0.660 0.202 

FSV-BK
 

FSV-BL
 

FSV-BM
 

FSV-BN
 0.006 0.021 0.016 0.010 0.009 0.128 0.449 0.269 0.110 0.139 0.122 0.428 0.253 0.101 0.130 0.090 0.022 0.040 0.017 0.096 0.508 1.005 0.632 0.265 

FSV-BNa 0.137 0.470 0.272 0.114 0.150 0.104 0.043 0.061 0.026 0.110 0.559 1.061 0.691 0.258 

FSV-BO
 0.113 0.331 0.219 0.091 0.114 0.069 0.009 0.025 0.006 0.067 0.390 0.658 0.471 0.188 

FSV-BP
 0.129 0.347 0.230 0.096 0.128 0.050 0.012 0.036 nd 0.053 0.448 0.830 0.565 0.254 

FSV-BQ
 

FSV-BR
 

FSV-BS
 ≥0.135 ≥0.439 ≥0.311 ≥0.081 ≥0.155 0.135 0.439 0.311 0.081 0.155 0.048 0.021 0.027 0.011 0.050 0.635 0.822 0.879 0.196 

FSV-BT 0.116 0.287 0.209 0.084 0.100 0.114 0.274 0.198 0.081 0.097 0.007 0.022 0.017 0.005 0.006 0.055 0.016 0.025 0.008 0.048 0.444 0.667 0.508 0.205 

FSV-BU 0.118 0.417 0.263 0.108 0.120 0.071 0.010 0.028 0.009 0.080 0.428 0.848 0.563 0.205 

FSV-BV
 0.135 0.444 0.291 0.112 0.149 0.105 0.016 0.041 0.009 0.114 0.607 1.077 0.761 0.278 

FSV-BW 0.109 0.466 0.260 0.096 0.123 0.056 nd 0.009 0.003 0.062 0.520 1.080 0.680 0.240 

FSV-CC
 

FSV-CD
 0.120 0.240 0.170 0.110 0.110 0.060 0.010 0.020 0.030 0.030 0.180 0.310 0.210 0.160 

FSV-CE
 0.080 0.422 0.161 0.073 0.100 

FSV-CF 

FSV-CG 0.095 0.358 0.232 0.081 0.108 0.090 0.341 0.218 0.076 0.103 0.005 0.017 0.014 0.005 0.005 0.078 0.021 0.041 0.010 0.088 0.446 0.914 0.630 0.220 

FSV-CI 0.126 0.448 0.251 0.086 0.132 0.080 0.045 0.045 0.015 0.087 

FSV-CW 0.116 0.307 0.215 0.097 0.118 0.064 0.019 0.032 0.009 0.069 

FSV-CZ 0.119 0.281 0.191 0.077 0.104
 

FSV-DA
 0.108 0.336 0.215 0.086 0.122 0.101 0.311 0.195 0.074 0.115 0.007 0.025 0.019 0.013 0.007 0.063 0.009 0.021 0.005 0.060 0.451 0.891 0.572 0.215 

FSV-DD 

FSV-DI 0.118 0.365 0.265 0.110 0.099 0.580 0.950 0.689 0.275 

FSV-DV
 

FSV-EE
 

FSV-EZ
 ≥0.066 ≥0.275 ≥0.186 ≥0.085 ≥0.064 0.066 0.275 0.186 0.085 0.064 

N 

Min 

Median 

Max 

SD 

Npast 

Medianpast 

SDpast 

NNIST 

MeanNIST 

Srep 

Shet 

SNIST 

23 23 23 

0.080 0.240 0.159 

0.117 0.395 0.232 

0.143 0.470 0.291 

0.014 0.079 0.034 

12 20 15 

24 24 24 

0.114 0.386 0.241 

0.017 0.070 0.036 

23 

0.065 

0.091 

0.114 

0.014 

15 

24 

0.090 

0.010 

23 

0.093 

0.117 

0.150 

0.016 

14 

24 

0.122 

0.018 

9 9 9 9 9 

0.066 0.274 0.151 0.063 0.064 

0.105 0.341 0.218 0.080 0.108 

0.135 0.439 0.311 0.101 0.155 

0.022 0.096 0.034 0.006 0.016 

21 28 16 7 15 

10 9 9 9 10 

0.111 0.344 0.213 0.083 0.117 

0.011 0.039 0.016 0.006 0.011 

6 

0.005 

0.006 

0.012 

0.001 

23 

6 

0.006 

0.003 

7 

0.009 

0.021 

0.025 

0.006 

28 

8 

0.016 

0.002 

7 

0.008 

0.014 

0.019 

0.004 

32 

8 

0.013 

0.001 

6 

0.002 

0.007 

0.013 

0.005 

73 

5 

0.005 

0.001 

6 

0.005 

0.008 

0.010 

0.002 

31 

6 

0.006 

0.002 

19 17 18 16 19 

0.048 0.005 0.009 0.002 0.030 

0.069 0.016 0.031 0.009 0.069 

0.105 0.045 0.061 0.030 0.114 

0.017 0.008 0.014 0.004 0.023 

24 53 45 43 34 

21 19 20 18 21 

0.076 0.016 0.030 0.008 0.081 

0.013 0.006 0.004 0.004 0.012 

18 18 18 18 

0.180 0.310 0.210 0.160 

0.514 0.927 0.631 0.216 

0.635 1.133 0.879 0.278 

0.098 0.177 0.088 0.037 

19 19 14 17 

20 19 19 19 

0.480 0.965 0.594 0.236 

0.062 0.219 0.079 0.025 

11 11 11 

0.431 0.246 0.114 

0.023 0.020 0.003 

0.000 0.000 0.002 

0.023 0.020 0.004 

11 11 11 

0.382 0.193 0.093 

0.019 0.018 0.005 

0.000 0.000 0.000 

0.019 0.018 0.005 

11 11 11 

0.052 0.053 0.021 

0.021 0.013 0.004 

0.000 0.000 0.001 

0.021 0.013 0.004 

11 

nq 0.034 nq 

0.003 

0.000 

0.003 

11 11 11 

0.717 0.394 0.173 

0.032 0.015 0.004 

0.000 0.000 0.001 

0.032 0.015 0.004 

0.117 0.413 0.239 0.102 0.117 

0.019 0.083 0.036 0.022 0.019 

0.105 0.361 0.206 0.086 0.108 

0.022 0.101 0.038 0.014 0.016 

0.006 0.036 0.034 0.014 0.008 

0.003 0.030 0.030 0.011 0.004 

0.069 0.016 0.033 0.009 0.069 

0.020 0.008 0.014 0.004 0.023 

0.514 0.822 0.512 0.194 

0.106 0.231 0.209 0.060 

NAV 

NAU 

All Lab R eport 

CV 
 

Round Robin LXVII Laboratory Results 

Total β-Cryptoxanthin, μg/mL Total α-Cryptoxanthin, μg/mL Total Lutein, μg/mL Total Zeaxanthin, μg/mL Total Lutein&Zeaxanthin, μg/mL 

Lab 362 363 364 365 366 

C4

FSV-BA 0.057 0.042 0.057 0.050 0.058 

FSV-BB 0.046 0.033 0.048 0.046 0.052 

FSV-BC 

FSV-BD 

FSV-BE 

FSV-BF 

FSV-BG 0.059 0.033 0.057 0.053 0.063 

FSV-BH 0.064 0.053 0.065 0.057 0.068 

FSV-BJ 0.043 0.031 0.040 0.037 0.047 

FSV-BK 

FSV-BL 

FSV-BM 

FSV-BN 0.055 0.031 0.056 0.055 0.060 

FSV-BNa 0.051 0.019 0.046 0.041 0.052 

FSV-BO 0.053 0.029 0.053 0.051 0.055 

FSV-BP 0.047 0.024 0.047 0.040 0.049 

FSV-BQ 

FSV-BR 

FSV-BS 0.041 0.014 0.071 0.048 0.069 

FSV-BT 0.045 0.029 0.040 0.038 0.041 

FSV-BU 0.040 0.022 0.045 0.046 0.051 

FSV-BV 0.036 0.016 0.034 0.034 0.041 

FSV-BW 0.060 0.010 0.040 0.050 0.050 

FSV-CC 

FSV-CD 0.050 0.040 0.050 0.050 0.050 

FSV-CE 

FSV-CF 

FSV-CG 0.066 0.061 0.078 0.063 0.074 

FSV-CI 

FSV-CW 0.036 0.022 0.035 0.037 0.039 

FSV-CZ 

FSV-DA 0.060 0.051 0.067 0.054 0.063 

FSV-DD 

FSV-DI 

FSV-DV 

FSV-EE 

FSV-EZ 

362 363 364 365 366 

0.025 0.019 0.023 0.017 0.024 

0.023 0.017 0.022 0.017 0.025 

0.025 0.014 0.024 0.021 0.026 

0.029 0.031 0.028 0.020 0.027 

≤0.01 ≤0.01 ≤0.01 ≤0.01 ≤0.01 

0.026 0.018 0.027 0.018 0.026 

362 363 364 365 366 

0.072 0.133 0.091 0.073 0.072 

0.054 0.093 0.072 0.059 0.060 

0.082 0.120 0.096 0.080 0.087 

0.052 0.099 0.075 0.066 0.060 

0.143 0.154 0.141 0.152 0.121 

0.061 0.126 0.101 0.082 0.077 

0.044 0.053 0.049 0.047 0.039 

0.071 0.113 0.085 0.067 0.065 

0.070 0.129 0.090 0.058 0.077 

0.078 0.130 0.100 0.085 0.090 

362 363 364 365 366 

0.045 0.058 0.046 0.047 0.040 

0.028 0.027 0.035 0.035 0.029 

0.019 0.022 0.024 0.035 0.028 

0.013 0.013 0.011 0.007 0.010 

0.027 0.032 0.029 0.037 0.036 

0.030 0.031 0.029 0.029 0.027 

0.021 0.020 0.021 0.023 0.019 

0.030 0.039 0.037 0.034 0.036 

362 363 364 365 36

0.095 0.146 0.119 0.093 0.1

0.117 0.191 0.137 0.120 0.1

0.112 0.188 0.139 0.104 0.1

0.082 0.120 0.107 0.094 0.0

0.069 0.118 0.097 0.098 0.0

0.064 0.121 0.103 0.105 0.0

0.156 0.167 0.151 0.159 0.1

0.085 0.130 0.122 0.102 0.1

0.088 0.158 0.130 0.119 0.1

0.089 0.100 0.093 0.090 0.0

0.106 0.154 0.138 0.108 0.1

0.095 0.125 0.111 0.100 0.0

0.090 0.130 0.110 0.100 0.1

0.250 0.310 0.250 0.250 0.2

0.122 0.182 0.158 0.142 0.1

0.092 0.133 0.107 0.090 0.08

0.117 0.139 0.117 0.114 0.1

0.100 0.168 0.127 0.092 0.1

N 18 18 18 18 18 5 5 5 5 5 10 10 10 10 10 8 8 8 8 8 18 18 18 18 

Min 0.036 0.010 0.034 0.034 0.039 0.023 0.014 0.022 0.017 0.024 0.044 0.053 0.049 0.047 0.039 0.013 0.013 0.011 0.007 0.010 0.064 0.100 0.093 0.090 0.0

Median 0.051 0.030 0.049 0.049 0.052 0.025 0.018 0.024 0.018 0.026 0.070 0.123 0.091 0.070 0.075 0.028 0.029 0.029 0.035 0.028 0.095 0.143 0.121 0.103 0.1

Max 0.066 0.061 0.078 0.063 0.074 0.029 0.031 0.028 0.021 0.027 0.143 0.154 0.141 0.152 0.121 0.045 0.058 0.046 0.047 0.040 0.250 0.310 0.250 0.250 0.2

SD 0.012 0.013 0.013 0.008 0.010 0.001 0.002 0.003 0.001 0.001 0.016 0.015 0.015 0.017 0.020 0.007 0.012 0.010 0.006 0.011 0.018 0.032 0.022 0.016 0.0

CV 23 45 26 17 20 4 10 13 4 5 22 12 16 24 27 24 41 35 17 39 19 23 19 15 

Npast 21 20 20 20 21 6 4 4 4 7 14 10 10 10 14 12 9 9 9 12 21 20 20 20 

Medianpast 0.052 0.029 0.049 0.047 0.055 0.024 0.015 0.021 0.016 0.026 0.079 0.115 0.088 0.072 0.081 0.030 0.034 0.032 0.037 0.031 0.109 0.142 0.130 0.110 0.1

SDpast 0.008 0.006 0.005 0.007 0.010 0.006 0.002 0.004 0.004 0.006 0.014 0.031 0.020 0.012 0.014 0.007 0.015 0.019 0.012 0.008 0.018 0.026 0.027 0.010 0.0

11 11 11 11 11 11 11 11 11 11 11 11
 

MeanNIST
 

NNIST 

0.017 0.036 0.041 0.131 0.100 0.069 0.027 0.029 0.029 0.157 0.129 0.098 

0.001 0.002 0.002 0.007 0.006 0.005 0.004 0.002 0.003 0.010 0.007 0.006 Srep 

0.001 0.002 0.002 0.000 0.002 0.000 0.000 0.000 0.001 0.000 0.001 0.000 Shet 

0.001 0.003 0.003 0.007 0.006 0.005 0.004 0.002 0.003 0.010 0.007 0.006
 

NAV
 

SNIST 

0.051 0.023 0.042 0.045 0.052 0.025 0.018 0.024 0.018 0.026 0.070 0.127 0.095 0.069 0.075 0.028 0.028 0.029 0.032 0.028 0.095 0.150 0.125 0.100 0.1

NAU 0.012 0.016 0.016 0.013 0.013 0.001 0.002 0.003 0.001 0.001 0.016 0.024 0.019 0.017 0.020 0.008 0.012 0.010 0.010 0.011 0.020 0.034 0.026 0.022 0.0

All Lab R eport 
Round Robin LXVII Laboratory Results 

25-hydroxyvitamin D, μg/mL Phylloquinone (K1), ng/mL 

Lab 362 363 364 365 366 

C5

FSV-BA 0.021 0.021 0.014 0.007 0.022 

FSV-BB 

FSV-BC 

FSV-BD 

FSV-BE 

FSV-BF 

FSV-BG 

FSV-BH 0.028 0.027 0.020 0.011 0.027 

FSV-BJ 

FSV-BK 

FSV-BL 

FSV-BM 

FSV-BN 

FSV-BNa 0.017 0.015 0.019 0.008 0.025 

FSV-BO 0.008 0.009 0.006 0.003 0.009 

FSV-BP 

FSV-BQ 

FSV-BR 

FSV-BS 

FSV-BT 

FSV-BU 

FSV-BV 

FSV-BW 

FSV-CC 

FSV-CD 

FSV-CE 

FSV-CF 

FSV-CG 

FSV-CI 

FSV-CW 

FSV-CZ 

FSV-DA 

FSV-DD 

FSV-DI 

FSV-DV 

FSV-EE 

FSV-EZ 

362 363 364 365 366 

0.455 3.050 0.572 0.464 0.519 

0.453 2.562 0.564 0.396 0.480 

N 

Min 

Median 

Max 

SD 

CV 

Npast 

Medianpast 

SDpast 

NNIST 

MeanNIST 

Srep 

Shet 

SNIST 

NAV 

NAU 

4 4 4 4 4 

0.008 0.009 0.006 0.003 0.009 

0.019 0.018 0.016 0.008 0.024 

0.028 0.027 0.020 0.011 0.027 

0.009 0.009 0.004 0.003 0.004 

45 49 25 34 16 

5 0 0 0 9 

0.018 0.020 

0.003 0.001 

0.019 0.018 0.016 0.008 0.024 

2 2 2 2 2 

0.453 2.562 0.564 0.396 0.480 

0.454 2.806 0.568 0.430 0.500 

0.455 3.050 0.572 0.464 0.519 

0 0 0 0 0 

All Lab R eport 
 

 

 

 

 

 

 

 

Round Robin LXVII Laboratory Results 

Analytes Reported By One Laboratory 

Term 

N Number of (non-NIST) quantitative values reported for this analyte

Min Minimum (non-NIST) quantitative value reported

Median Median (non-NIST) quantitative value reported

Max Maximum (non-NIST) quantitative value reported

SD Standard deviation for (non-NIST) results: 0.741*(3rd Quartile - 1st Quartile)

CV Coefficient of Variation for (non-NIST) results: 100*SD/Median

Npast Mean of N(s) from past RR(s)

Medianpast Mean of Median(s) from past RR(s)

SDpast Pooled SD from past RR(s)

NNIST Number of units evaluated at NIST

MeanNIST Mean of NIST results

Srep NIST's within-vial pooled standard deviation

Shet NIST's among-vial pooled standard deviation 

SNIST Combined standard deviation for NIST analyses: √(Srep 2

 + Shet 2)

NAV NIST Assigned Value

 = (Median + MeanNIST)/2 for analytes reported by NIST analyst(s) 

= Median for analytes reported by ≥ 5 labs but not NIST

NAU NIST Assigned Uncertainty: √(S 2

 + Sbtw 2)

 S is the maximum of (0.05*NAV, SD, SNIST, eSD) and Sbtw is the standard

 deviation between Median and MeanNIST. The expected long-term SD, eSD,

 is defined in: Duewer et al., Anal Chem 1997;69(7):1406-1413.

nd Not detected (i.e., no detectable peak for analyte)

nq Detected but not quantitatively determined 

≤x Concentration at or below the limit of quantification, x

≥x Concentration greater than or equal to x

italics Not explicitly reported but calculated by NIST from reported values 

Analyte Code 362 363 364 365 366 

Phytofluene, μg/mL FSV-DA 0.100 0.187 0.098 0.031 0.121 

Phytoene, μg/mL FSV-DA 0.159 0.143 0.109 0.017 0.197 

Retinyl Stearate, μg/mL FSV-DA 0.029 0.034 0.009 nd 0.033 

Ubiquinol, μg/mL FSV-BW 1.00 1.02 0.58 0.85 0.81 

Ubiquinone, μg/mL FSV-BW 0.30 0.53 0.33 0.26 0.51 

Legend

All Lab Report 

C6

Page 5 / 6 
 

 

 

 

 

 

 

 

 

Lab 

FSV-BA 

FSV-BB 

FSV-BC 

FSV-BD 

FSV-BE 

FSV-BF 

FSV-BG 

FSV-BH 

FSV-BJ 

FSV-BK 

FSV-BL 

FSV-BM 

FSV-BN 

FSV-BNa 

FSV-BO 

FSV-BP 

FSV-BQ 

FSV-BR 

FSV-BS 

FSV-BT 

FSV-BU 

FSV-BV 

FSV-BW 

FSV-CC 

FSV-CD 

FSV-CE 

FSV-CF 

FSV-CG 

FSV-CI 

FSV-CW 

FSV-CZ 

FSV-DA 

FSV-DD 

FSV-DI 

FSV-DV 

FSV-EE 

FSV-EZ 

NIST 

n 

% 1
 

% 2
 

% 3
 

% 4
 

Round Robin LXVII Laboratory Results 

Comparability Summary 

TR aT g/bT bC tbC aC TLy TbX TLu TZ L&Z 

1 1 1 1 1 1 1 1 1
 

1 1 1 2 2 2 1 1 1 2 1
 

1
 

1 2
 

2 1 1 1
 

1 1 1
 

1 1 1 2 1 1 1 1
 

1 1 1 1 1 1 1 2 1 1 1
 

1 1 1 1 2 1 1 1
 

2 1
 

1 1
 

1 1
 

1 2 1 2 2 1 1 1 1 1
 

1 2 2 3 1 1 1
 

2 1 1 1 1 1 1 4 2 3
 

1 1 1 1 1 1 1
 

4 4
 

2 2
 

2 2 2 1 2 2 1 1 1
 

2 1 1 1 1 1 1 1 3 1 2
 

2 2 2 1 1 1 1 1
 

1 1 2 2 2 1 2 1
 

1 1 1 1 2 1 1 1
 

3 2
 

3 2 1 2 3 3 1 4
 

1 2 2
 

1 2
 

1 2 1 1 1 1 1 2 2
 

1 2 1 1 2 1 1 1
 

1 2 3 1 1 1 1
 

1 4 1 1
 

1 1 1 1 1 1 1 1 1 1 1
 

2
 

2 2 1 1 1 1
 

2 4
 

1 1
 

2 1 1 2 2
 

1 1 1 1 1 1
 

38 35 20 26 10 19 19 18 10 8 18
 

TR aT g/bT bC tbC aC TLy TbX TLu TZ L&Z
 

63 54 85 69 60 58 89 78 80 75 78
 

29 37 10 31 40 32 5 22 0 25 11
 

5 0 5 0 0 11 5 0 10 0 6
 

3 9 0 0 0 0 0 0 10 0 6
 

Label

Lab 

TR

aT

g/bT 

bC

tbC

aC

TLy

TbX 

TLu 

TZ

L&Z

n 

% 1

% 2

% 3

% 4

 Definition 

 Participant code 

 Total Retinol 

α-Tocopherol 

γ/β-Tocopherol 

 Total β-Carotene 

 trans-β-Carotene 

 Total α-Carotene 

 Total Lycopene 

Total β-Cryptoxanthin 

 Total Lutein 

 Total Zeaxanthin 

 Total Lutein & Zeaxanthin 

 number of participants providing quantitative data 

 Percent of CS = 1 (within 1 SD of medians) 

 Percent of CS = 2 (within 2 SD of medians) 

 Percent of CS = 3 (within 3 SD of medians) 

 Percent of CS = 4 (3 or more SD from medians) 

“Comparability Score” 

The Comparability Score (CS) of summarizes your measurement 

performance for a given measurand, relative to the consensus 

medians. CS is the average distance, in standard deviation units, 

that your measurement performance characteristics are from the 

consensus performance. CS is calculated when the number of 

quantitative values you reported for a measurand, Nyou, is at least 

two and the measurand has been reported by 10 or more 

participants. 

CS = MIN(4, INT(1 + C2 + AP 2 )) 

N yo u You − Median C = Concordanc e = i i ∑ Ny ou
 NAU i i
 

N yo u  You i − Median i 

2
 

AP = Apparent Precision = ∑  (Ny ou − 1)   NAU i  i  

NAU = NIST Assigned Uncertainty, our estimate of the overall 

measurement standard deviation for each sample. The 

estimate includes serum heterogeneity, analytical 

repeatability, and among-participant reproducibility variance 

components. 

For further details, please see: Duewer DL, Kline MC, Sharpless 

KE, Brown Thomas J, Gary KT. Micronutrients Measurement 

Quality Assurance Program: Helping participants use 

interlaboratory comparison exercise results to improve their longterm measurement performance. Anal Chem 1999;71(9):1870-8. 

All Lab Report 

C7

Page 6 / 6
 
 

Appendix D. Representative “Individualized Report” for RR67 

Each participant in RR67 received an “Individualized Report” reflecting their reported 

results. Each report included a detailed analysis for analytes that were assayed by at least 

five participants. The following analytes met this criterion in RR67: 

• Total Retinol 

• trans-Retinol 

• Retinyl Palmitate 

• α-Tocopherol 

• γ/β-Tocopherol 

• δ-Tocopherol 

• Total β-Carotene 

• trans-β-Carotene 

• Total cis-β-Carotene 

• Total α-Carotene 

• Total Lycopene 

• trans-Lycopene 

• Total β-Cryptoxanthin 

• Total Lutein 

• Total Zeaxanthin 

• Total Lutein & Zeaxanthin 

• Coenzyme Q10 

The following fourteen pages are the “Individualized Report” for the analytes evaluated 

by participant FSV-BA. 

D1
 

 Set 1 of 39 

Individualized Round Robin LXVII Report: FSV-BA 

Summary 

Serum 362 Serum 363 Serum 364 Serum 365 

D2

Analyte You NAV n You NAV n You NAV n You NAV n Yo

Total Retinol 0.616 0.614 34 0.665 0.653 34 0.517 0.504 34 0.366 0.353 34 0.6

Retinyl Palmitate 0.11 0.08 11 0.2 0.1 11 0.1 0.0 9 0.02 0.01 7 0.

α-Tocopherol 9.750 9.815 34 18.300 19.014 34 9.990 10.087 34 6.460 6.843 34 10.2

γ/β-Tocopherol 1.900 1.696 19 2.540 2.302 19 1.540 1.448 19 1.950 1.931 19 1.9

δ-Tocopherol 0.057 0.078 6 0.221 0.221 7 0.046 0.106 7 0.098 0.120 7 0.0

Total β-Carotene 0.117 0.117 23 0.395 0.413 23 0.246 0.239 23 0.091 0.102 23 0.1

trans-β-Carotene 0.105 0.105 9 0.374 0.361 9 0.232 0.206 9 0.079 0.086 9 0.1

Total cis-β-Carotene 0.012 0.006 6 0.021 0.036 7 0.014 0.034 7 0.012 0.014 6 0.0

Total α-Carotene 0.063 0.069 19 0.014 0.016 17 0.030 0.033 18 0.008 0.009 16 0.0

Total Lycopene 0.536 0.514 18 0.939 0.822 18 0.657 0.512 18 0.201 0.194 18 0.4

trans-Lycopene 0.266 0.258 9 0.415 0.513 9 0.298 0.316 9 0.110 0.134 9 0.2

Total β-Cryptoxanthin 0.057 0.051 18 0.042 0.023 18 0.057 0.042 18 0.050 0.045 18 0.0

Total α-Cryptoxanthin 0.025 0.025 5 0.019 0.018 5 0.023 0.024 5 0.017 0.018 5 0.0

Total Lutein&Zeaxanthin 0.095 0.095 18 0.146 0.150 18 0.119 0.125 18 0.093 0.100 18 0.1

25-hydroxyvitamin D 0.021 0.019 4 0.021 0.018 4 0.014 0.016 4 0.007 0.008 4 0.0

You : Your reported values for the listed analytes (micrograms/milliliter) 

NAV : NIST Assigned Values, here equal to this RR's median 

n : Number of non-NIST laboratories reporting quantitative values for this analyte in this serum 

Please check our records against your records. Send corrections and/or updates to... 

Micronutrients Measurement Quality Assurance Program 

National Institute of Standards and Technology Te

100 Bureau Drive Stop 8392 Fax

Gaithersburg, MD 20899-8392 USA Email: david.d

Individualized Report 
D3

 Set 1 of 40 

Individualized RR LXVII Report: FSV-BA

Total Retinol, μg/mL 

Apparent Precision, SD [Analyte], μg/mL

290300312322333348362292301313323332349366357365358364359363 

Your [Analyte], μg/mL 

Apparent Precision, SD 

Concordance, SD 

Median [Analyte], μg/mL 

Long-term Precision, SD 

3rd Quartile (75%) You, this RR You, ≥x, this RR NIST, this RR 

Median (50%) You, past RRs You, ≥x, past RRs Others, this RR 

1st Quartile (25%) Expectation 

For details of the construction and interpretation of these plots, see: 

Duewer, Kline, Sharpless, Brown Thomas, Gary, Sowell. Anal Chem 1999;71(9):1870-8. 

Serum History Comments 

#362 53#290, 55#300, 57#312, 59#322, 61#333, 64#348 Lyophilized, native, single-donor 

#363 66#359 Fresh-frozen, native, single-donor 

#364 66#358 Fresh-frozen, native, multi-donor 

#365 66#357 Fresh-frozen, native, multi-donor 

#366 53#292, 55#301, 57#313, 59#323, 61#332, 64#349 Fresh-frozen, native, single-donor 

Individualized Report Page 2 / 14 
D4

 Set 1 of 40 

Individualized RR LXVII Report: FSV-BA

Retinyl Palmitate, μg/mL 

Apparent Precision, SD [Analyte], μg/mL

290300312322333348362292301313323332349366357365358364359363 

Your [Analyte], μg/mL 

Apparent Precision, SD 

Concordance, SD 

Median [Analyte], μg/mL 

Long-term Precision, SD 

3rd Quartile (75%) You, this RR You, ≥x, this RR NIST, this RR 

Median (50%) You, past RRs You, ≥x, past RRs Others, this RR 

1st Quartile (25%) Expectation 

For details of the construction and interpretation of these plots, see: 

Duewer, Kline, Sharpless, Brown Thomas, Gary, Sowell. Anal Chem 1999;71(9):1870-8. 

Serum History Comments 

#362 53#290, 55#300, 57#312, 59#322, 61#333, 64#348 Lyophilized, native, single-donor 

#363 66#359 Fresh-frozen, native, single-donor 

#364 66#358 Fresh-frozen, native, multi-donor 

#365 66#357 Fresh-frozen, native, multi-donor 

#366 53#292, 55#301, 57#313, 59#323, 61#332, 64#349 Fresh-frozen, native, single-donor 

Individualized Report Page 3 / 14 
D5

 Set 1 of 40 

Individualized RR LXVII Report: FSV-BA

α-Tocopherol, μg/mL 

Apparent Precision, SD [Analyte], μg/mL

290300312322333348362292301313323332349366357365358364359363 

Your [Analyte], μg/mL 

Apparent Precision, SD 

Concordance, SD 

Median [Analyte], μg/mL 

Long-term Precision, SD 

3rd Quartile (75%) You, this RR You, ≥x, this RR NIST, this RR 

Median (50%) You, past RRs You, ≥x, past RRs Others, this RR 

1st Quartile (25%) Expectation 

For details of the construction and interpretation of these plots, see: 

Duewer, Kline, Sharpless, Brown Thomas, Gary, Sowell. Anal Chem 1999;71(9):1870-8. 

Serum History Comments 

#362 53#290, 55#300, 57#312, 59#322, 61#333, 64#348 Lyophilized, native, single-donor 

#363 66#359 Fresh-frozen, native, single-donor 

#364 66#358 Fresh-frozen, native, multi-donor 

#365 66#357 Fresh-frozen, native, multi-donor 

#366 53#292, 55#301, 57#313, 59#323, 61#332, 64#349 Fresh-frozen, native, single-donor 

Individualized Report Page 4 / 14 
D6

 Set 1 of 40 

Individualized RR LXVII Report: FSV-BA

γ/β-Tocopherol, μg/mL 

Apparent Precision, SD [Analyte], μg/mL

290300312322333348362292301313323332349366357365358364359363 

Your [Analyte], μg/mL 

Apparent Precision, SD 

Concordance, SD 

Median [Analyte], μg/mL 

Long-term Precision, SD 

3rd Quartile (75%) You, this RR You, ≥x, this RR NIST, this RR 

Median (50%) You, past RRs You, ≥x, past RRs Others, this RR 

1st Quartile (25%) Expectation 

For details of the construction and interpretation of these plots, see: 

Duewer, Kline, Sharpless, Brown Thomas, Gary, Sowell. Anal Chem 1999;71(9):1870-8. 

Serum History Comments 

#362 53#290, 55#300, 57#312, 59#322, 61#333, 64#348 Lyophilized, native, single-donor 

#363 66#359 Fresh-frozen, native, single-donor 

#364 66#358 Fresh-frozen, native, multi-donor 

#365 66#357 Fresh-frozen, native, multi-donor 

#366 53#292, 55#301, 57#313, 59#323, 61#332, 64#349 Fresh-frozen, native, single-donor 

Individualized Report Page 5 / 14 
D7

 Set 1 of 40 

Individualized RR LXVII Report: FSV-BA

Total β-Carotene, μg/mL 

Apparent Precision, SD [Analyte], μg/mL

290300312322333348362292301313323332349366357365358364359363 

Your [Analyte], μg/mL 

Apparent Precision, SD 

Concordance, SD 

Median [Analyte], μg/mL 

Long-term Precision, SD 

3rd Quartile (75%) You, this RR You, ≥x, this RR NIST, this RR 

Median (50%) You, past RRs You, ≥x, past RRs Others, this RR 

1st Quartile (25%) Expectation 

For details of the construction and interpretation of these plots, see: 

Duewer, Kline, Sharpless, Brown Thomas, Gary, Sowell. Anal Chem 1999;71(9):1870-8. 

Serum History Comments 

#362 53#290, 55#300, 57#312, 59#322, 61#333, 64#348 Lyophilized, native, single-donor 

#363 66#359 Fresh-frozen, native, single-donor 

#364 66#358 Fresh-frozen, native, multi-donor 

#365 66#357 Fresh-frozen, native, multi-donor 

#366 53#292, 55#301, 57#313, 59#323, 61#332, 64#349 Fresh-frozen, native, single-donor 

Individualized Report Page 6 / 14 
D8

 Set 1 of 40 

Individualized RR LXVII Report: FSV-BA

trans-β-Carotene, μg/mL 

Apparent Precision, SD [Analyte], μg/mL

290300312322333348362292301313323332349366357365358364359363 

Your [Analyte], μg/mL 

Apparent Precision, SD 

Concordance, SD 

Median [Analyte], μg/mL 

Long-term Precision, SD 

3rd Quartile (75%) You, this RR You, ≥x, this RR NIST, this RR 

Median (50%) You, past RRs You, ≥x, past RRs Others, this RR 

1st Quartile (25%) Expectation 

For details of the construction and interpretation of these plots, see: 

Duewer, Kline, Sharpless, Brown Thomas, Gary, Sowell. Anal Chem 1999;71(9):1870-8. 

Serum History Comments 

#362 53#290, 55#300, 57#312, 59#322, 61#333, 64#348 Lyophilized, native, single-donor 

#363 66#359 Fresh-frozen, native, single-donor 

#364 66#358 Fresh-frozen, native, multi-donor 

#365 66#357 Fresh-frozen, native, multi-donor 

#366 53#292, 55#301, 57#313, 59#323, 61#332, 64#349 Fresh-frozen, native, single-donor 

Individualized Report Page 7 / 14 
D9

 Set 1 of 40 

Individualized RR LXVII Report: FSV-BA

Total cis-β-Carotene, μg/mL 

Apparent Precision, SD [Analyte], μg/mL

290300312322333348362292301313323332349366357365358364359363 

Your [Analyte], μg/mL 

Apparent Precision, SD 

Concordance, SD 

Median [Analyte], μg/mL 

Long-term Precision, SD 

3rd Quartile (75%) You, this RR You, ≥x, this RR NIST, this RR 

Median (50%) You, past RRs You, ≥x, past RRs Others, this RR 

1st Quartile (25%) Expectation 

For details of the construction and interpretation of these plots, see: 

Duewer, Kline, Sharpless, Brown Thomas, Gary, Sowell. Anal Chem 1999;71(9):1870-8. 

Serum History Comments 

#362 53#290, 55#300, 57#312, 59#322, 61#333, 64#348 Lyophilized, native, single-donor 

#363 66#359 Fresh-frozen, native, single-donor 

#364 66#358 Fresh-frozen, native, multi-donor 

#365 66#357 Fresh-frozen, native, multi-donor 

#366 53#292, 55#301, 57#313, 59#323, 61#332, 64#349 Fresh-frozen, native, single-donor 

Individualized Report Page 8 / 14 
D10

 Set 1 of 40 

Individualized RR LXVII Report: FSV-BA

Total α-Carotene, μg/mL 

Apparent Precision, SD [Analyte], μg/mL

290300312322333348362292301313323332349366357365358364359363 

Your [Analyte], μg/mL 

Apparent Precision, SD 

Concordance, SD 

Median [Analyte], μg/mL 

Long-term Precision, SD 

3rd Quartile (75%) You, this RR You, ≥x, this RR NIST, this RR 

Median (50%) You, past RRs You, ≥x, past RRs Others, this RR 

1st Quartile (25%) Expectation 

For details of the construction and interpretation of these plots, see: 

Duewer, Kline, Sharpless, Brown Thomas, Gary, Sowell. Anal Chem 1999;71(9):1870-8. 

Serum History Comments 

#362 53#290, 55#300, 57#312, 59#322, 61#333, 64#348 Lyophilized, native, single-donor 

#363 66#359 Fresh-frozen, native, single-donor 

#364 66#358 Fresh-frozen, native, multi-donor 

#365 66#357 Fresh-frozen, native, multi-donor 

#366 53#292, 55#301, 57#313, 59#323, 61#332, 64#349 Fresh-frozen, native, single-donor 

Individualized Report Page 9 / 14 
D11

 Set 1 of 40 

Individualized RR LXVII Report: FSV-BA

Total Lycopene, μg/mL 

Apparent Precision, SD [Analyte], μg/mL

290300312322333348362292301313323332349366357365358364359363 

Your [Analyte], μg/mL 

Apparent Precision, SD 

Concordance, SD 

Median [Analyte], μg/mL 

Long-term Precision, SD 

3rd Quartile (75%) You, this RR You, ≥x, this RR NIST, this RR 

Median (50%) You, past RRs You, ≥x, past RRs Others, this RR 

1st Quartile (25%) Expectation 

For details of the construction and interpretation of these plots, see: 

Duewer, Kline, Sharpless, Brown Thomas, Gary, Sowell. Anal Chem 1999;71(9):1870-8. 

Serum History Comments 

#362 53#290, 55#300, 57#312, 59#322, 61#333, 64#348 Lyophilized, native, single-donor 

#363 66#359 Fresh-frozen, native, single-donor 

#364 66#358 Fresh-frozen, native, multi-donor 

#365 66#357 Fresh-frozen, native, multi-donor 

#366 53#292, 55#301, 57#313, 59#323, 61#332, 64#349 Fresh-frozen, native, single-donor 

Individualized Report Page 10 / 14 
D12

 Set 1 of 40 

Individualized RR LXVII Report: FSV-BA

trans-Lycopene, μg/mL 

Apparent Precision, SD [Analyte], μg/mL

290300312322333348362292301313323332349366357365358364359363 

Your [Analyte], μg/mL 

Apparent Precision, SD 

Concordance, SD 

Median [Analyte], μg/mL 

Long-term Precision, SD 

3rd Quartile (75%) You, this RR You, ≥x, this RR NIST, this RR 

Median (50%) You, past RRs You, ≥x, past RRs Others, this RR 

1st Quartile (25%) Expectation 

For details of the construction and interpretation of these plots, see: 

Duewer, Kline, Sharpless, Brown Thomas, Gary, Sowell. Anal Chem 1999;71(9):1870-8. 

Serum History Comments 

#362 53#290, 55#300, 57#312, 59#322, 61#333, 64#348 Lyophilized, native, single-donor 

#363 66#359 Fresh-frozen, native, single-donor 

#364 66#358 Fresh-frozen, native, multi-donor 

#365 66#357 Fresh-frozen, native, multi-donor 

#366 53#292, 55#301, 57#313, 59#323, 61#332, 64#349 Fresh-frozen, native, single-donor 

Individualized Report Page 11 / 14 
D13

 Set 1 of 40 

Individualized RR LXVII Report: FSV-BA

Total β-Cryptoxanthin, μg/mL 

Apparent Precision, SD [Analyte], μg/mL

290300312322333348362292301313323332349366357365358364359363 

Your [Analyte], μg/mL 

Apparent Precision, SD 

Concordance, SD 

Median [Analyte], μg/mL 

Long-term Precision, SD 

3rd Quartile (75%) You, this RR You, ≥x, this RR NIST, this RR 

Median (50%) You, past RRs You, ≥x, past RRs Others, this RR 

1st Quartile (25%) Expectation 

For details of the construction and interpretation of these plots, see: 

Duewer, Kline, Sharpless, Brown Thomas, Gary, Sowell. Anal Chem 1999;71(9):1870-8. 

Serum History Comments 

#362 53#290, 55#300, 57#312, 59#322, 61#333, 64#348 Lyophilized, native, single-donor 

#363 66#359 Fresh-frozen, native, single-donor 

#364 66#358 Fresh-frozen, native, multi-donor 

#365 66#357 Fresh-frozen, native, multi-donor 

#366 53#292, 55#301, 57#313, 59#323, 61#332, 64#349 Fresh-frozen, native, single-donor 

Individualized Report Page 12 / 14 
D14

 Set 1 of 40 

Individualized RR LXVII Report: FSV-BA

Total Lutein&Zeaxanthin, μg/mL 

Apparent Precision, SD [Analyte], μg/mL

290300312322333348362292301313323332349366357365358364359363 

Your [Analyte], μg/mL 

Apparent Precision, SD 

Concordance, SD 

Median [Analyte], μg/mL 

Long-term Precision, SD 

3rd Quartile (75%) You, this RR You, ≥x, this RR NIST, this RR 

Median (50%) You, past RRs You, ≥x, past RRs Others, this RR 

1st Quartile (25%) Expectation 

For details of the construction and interpretation of these plots, see: 

Duewer, Kline, Sharpless, Brown Thomas, Gary, Sowell. Anal Chem 1999;71(9):1870-8. 

Serum History Comments 

#362 53#290, 55#300, 57#312, 59#322, 61#333, 64#348 Lyophilized, native, single-donor 

#363 66#359 Fresh-frozen, native, single-donor 

#364 66#358 Fresh-frozen, native, multi-donor 

#365 66#357 Fresh-frozen, native, multi-donor 

#366 53#292, 55#301, 57#313, 59#323, 61#332, 64#349 Fresh-frozen, native, single-donor 

Individualized Report Page 13 / 14 
D15

 Set 1 of 39 

Individualized Round Robin LXVII Report: FSV-BA 

Graphical Comparability Summary
 

Total Retinol α-Tocopherol Total α-Carotene T

trans-Retinol γ/β-Tocopherol Total Lycopene Tot

Retinyl Palmitate Total β-Carotene trans-Lycopene Total L

trans-β-Carotene Total β-Cryptoxanthin Co

Individualized Report 
 

 

Appendix E. Shipping Package Inserts for RR32 

The following five items were included in each package shipped to an RR32 participant: 

•	 Cover letter 

•	 Protocol for Preparation and Analysis of the Ascorbic Acid Solid Control
 

Material
 

•	 Preparation and Validation of Ascorbic Acid Solid Control Material Datasheet 

•	 Analysis of Control Materials and Test Samples Datasheet 

•	 Packing List and Shipment Receipt Confirmation Form 

The cover letter, preparation protocol, and the two datasheets were enclosed in a sealed 

waterproof bag along with the samples themselves. The packing list was placed at the 

top of the shipping box, between the cardboard covering and the foam insulation. 

E1
December 11, 2009 

Dear Colleague: 

UN~D STA°!ES DEPARTMENT OF COMMERCE 

National Institute of Standards and Technalagy 

Gaithersburg, Maryland 20899-

The samples within this package constitute Vitamin C Round Robin 32 (RR32) of the 2010 Micronutrients 

Measurement Quality Assurance Program. RR32 consists of four vials of frozen serum test samples (#321, #3 22, 

#323, and #324), one vial of frozen control serum (CS #2), and one vial of ascorbic acid solid control material 

(Control). Please follow the attached protocols when you prepare and analyze these samples. If you cannot 

prepare the solid control solutions gravimetrically, please prepare equivalent solutions volumetrically and report 

the exact volumes used. (Routine 0.5 g gravimetric measurements are generally I 0-fold more accurate than routine 

0.5 mL volumetric measurements). 

Please use the control serum to validate the performance of your measurement system before you analyze the test 

samples. The target value and ::::95% confidence interval for target value and ::::95% confidence interval for CS #2 

is 28.l ±1.0 μmol/L of sample. 

The report for RR3 l was e-mailed in November. If you find yo':ll' results for RR31 unsatisfactory, we recommend 

that you obtain Standard Reference Material (SRM) 970 Ascorbic Acid in Serum to validate your methodology and 

value assign in-h9use control materials. This SRM may be purchased from the Standard Materials Reference 

Program at NIST (Tel: 301-975-6776, Fax: 301-948-3730, or e-mail: srminfo@nist.gov). 

Please be aware that sample contact with any oxidant-contaminated surface (vials, glassware, etc.) may degrade 

your measurement system's performance (SA Margolis and E Park, "Stability of Ascorbic Acid in Solutions in 

Autosampler Vials", Clinical Chemistry 2001, 47(8),_ 1463-1464). You should suspect such degradation if you 

observe unusually large variation in replicate analyses. 

If you have any questio.ns or concerns about the Vitamin C Micronutrients Measurement Quality Assurance 

· Program please contact Jeanice Brown Thomas at phone: 301-975-3120, fax: 301-977-0685, or 

e-mail: j bthomas@nist.gov. 

We ask that you return your results for these RR32 samples by March 15, 2010. We would appreciate receiving 

your results as soon as bee e available. Please use the attached form. Your results will be kept confidential. 

Enclosures: Protocols, Preparation and Analysis of Control Materials and"A~alysis ofT~st Samples 

RR32 Report Form for Ascorbic Acid Solid Control Material Preparation 

RR32 Report Form for Control Material and Test Sample Analyses 

E2
 

 

 

 

 

Micronutrient Measurement Quality Assurance Program for
 

Vitamin C
 

Please Read Through Completely BEFORE Analyzing Samples 

Protocol for Preparation and Analysis of the Ascorbic Acid Solid Control Material 

The ascorbic acid solid control material (in the amber vial) should be prepared and used in the 

following manner: 

1)	 Prepare at least 500 mL of 5% mass fraction metaphosphoric acid (MPA) in distilled water. This 

solution will be referred to as the “Diluent” below. 

2)	 Weigh 0.20 to 0.22 g of the ascorbic acid solid control material to 0.0001 g (if possible), dissolve 

it in the Diluent in a 100 mL volumetric flask, and dilute with the Diluent to the 100 mL mark. 

Weigh the amount of Diluent added to 0.1 g. Record the weights. The resulting material will be 

referred to as the “Stock Solution” below. 

3)	 Prepare three dilute solutions of the Stock Solution as follows: 

Dilute Solution 1: Weigh 0.500 mL of the Stock Solution to 0.0001 g into a 100 mL volumetric 

flask; dilute with Diluent to the 100 mL mark. Record the weight. 

Dilute Solution 2: Weigh 0.250 mL of the Stock Solution to 0.0001 g into a 100 mL volumetric 

flask; dilute with Diluent to the 100 mL mark. Record the weight. 

Dilute Solution 3: Weigh 0.125 mL of the Stock Solution to 0.0001 g into a 100 mL volumetric 

flask; dilute with Diluent to the 100 mL mark. Record the weight. 

4)	 Calculate and record the total ascorbic acid concentrations, [TAA], in these Dilute Solutions. 

If you follow the above gravimetric preparation directions, the [TAA] in μmol/L is calculated: 

(g Stock Solution in Dilute Solution 	 ) (⋅ g AA in Stock Solution )⋅(56785 mol/g μ ⋅ L) [TAA] DS = (g AA in Stock Solution ) + (g Diluent in Stock Solution)

For example, if you prepared the Stock Solution with 0.2000 g of solid ascorbic acid and 103.0 g 

of Diluent, then 0.5 mL of the Stock Solution should weigh (0.2+103)/200 = 0.52 g and 

[TAA]DS1 = (0.52 g)(0.2 g)∙(56785 μmol/g·L)/(0.2 + 103 g) = 57.2 μmol/L. Likewise, 0.25 mL 

of the Stock Solution should weigh 0.26 g and [TAA]DS2 = 29.4 μmol/L and 0.125 mL should 

weigh 0.13 g and [TAA]DS3 = 14.2 μmol/L. 

5)	 Measure the ultraviolet absorbance spectrum of Dilute Solution 1 against the Diluent as the blank 

using paired 1 cm path length cuvettes. Record the absorbance at 242, 243, 244, and 245 nm. 

Record the maximum absorbance (Amax) within this region. Record the wavelength (λmax) at 

which this maximum occurs. 

The extinction coefficient (E1%) of ascorbic acid at λmax (using a cell with a 1 cm path length) of 

Dilute Solution #1 can be calculated: 

E3
 

 

 

 

1% dL (A max )⋅	 ((g AA in Stock Solution ) + (gDiluent in Stock Solution )) E ( ) = g ⋅ cm (g Stock Solution in Dilute Solution 1)⋅(g AA in Stock Solution)

If your spectrophotometer is properly calibrated, λmax should be between 243 and 244 nm and 

E1% should be 550 ± 30 dL/g·cm. If they are not, you should recalibrate the wavelength and/or 

absorbance axes of your spectrophotometer and repeat the measurements. 

6)	 Measure and record the concentration of total ascorbic acid in all three dilute solutions and in the 

5% MPA Diluent in duplicate using exactly the same method that you will use for the serum 

control materials and test samples, including any enzymatic treatment. We recommend that you 

analyze these solutions in the following order: Diluent, Dilute Solution 1, Dilute Solution 2, 

Dilute Solution 3, Dilute Solution 3, Dilute Solution 2, Dilute Solution 1, Diluent. 

a)	 Compare the values of the duplicate measurements. Are you satisfied that your measurement 

precision is adequate? 

b)	 Compare the measured with the calculated [TAA] values. This is most conveniently done by 

plotting the measured values on the y-axis of a scatterplot against the calculated values on the 

x-axis. The line through the four {calculated, measured} data pairs should go through the 

origin with a slope of 1.0. Are you satisfied with the agreement between the measured and 

calculated values? 

Do not analyze the serum control materials or test samples until you are satisfied that your 

system is performing properly! 

7)	 Once you have confirmed that your system is properly calibrated, analyze the serum control 

CS #2 (see protocol below). The target values for this materials is 28.1 ±1.0 μmol/L of sample. 

If your measured values are not close to this value, please review your sample preparation 

procedure and whether you followed exactly the same measurement protocol the solutions 

prepared from the solid control material as you used for these serum controls. If the protocols 

differ, please repeat from Step 6 using the proper protocol. If the proper protocol was used, your 

measurement system may not be suitable for MPA-preserved samples; please contact us at 301­

975-3120 or jbthomas@NIST.gov. 

Do not analyze the test samples until you are satisfied that your system is performing properly 

and is suitable for the analysis of MPA-preserved serum! 

Protocol for Analysis of the Serum Control Materials and Test Samples 

The serum control material and test samples are in sealed ampoules. They were prepared by adding 

equal volumes of 10% MPA to spiked human serum. We have checked the samples for stability and 

homogeneity. Only the total ascorbic acid is stable. While these samples contain some 

dehydroascorbic acid, its content is variable. Therefore, only total ascorbic acid should be reported. 

The serum control material and test samples should be defrosted by warming at 20 °C for not more 

than 10 min otherwise some irreversible degradation may occur. 

Each serum test sample contains between 0.0 and 80.0 μmol of total ascorbic acid/L of solution. The 

total ascorbic acid in each ampoule should be measured in duplicate. Please report your results in 

μmol/(L of the sample solution) rather than μmol/(L of serum NIST used to prepare the sample). 

E4
 

 

Participant #: Date: 

Vitamin C Round Robin 32 

NIST Micronutrient Measurement Quality Assurance Program 

Preparation and Validation of Ascorbic Acid Solid Control Material 

STOCK SOLUTION 

Mass of ascorbic acid in the Stock Solution ..................................................__________ g 

Mass of 5% MPA Diluent added to the 100 mL volumetric flask .................__________ g 

DILUTE SOLUTION 1 

Mass of added stock solution (0.5 mL) ..........................................................__________ g 

Mass of 5% MPA Diluent added to the 100 mL volumetric flask .................__________ g 

Absorbance of Dilute Solution 1 at 242 nm...................................................__________ AU
 

Absorbance of Dilute Solution 1 at 243 nm...................................................__________ AU
 

Absorbance of Dilute Solution 1 at 244 nm...................................................__________ AU
 

Absorbance of Dilute Solution 1 at 245 nm...................................................__________ AU
 

Absorbance of Dilute Solution absorbance maximum ..................................__________ AU
 

Wavelength of maximum absorbance............................................................__________ nm
 

Calculated E1% ...............................................................................................__________ dL/g·cm
 

Calculated [TAA]DS1......................................................................................__________ μmol/L
	

DILUTE SOLUTION 2 

Mass of added stock solution (0.25 mL) ........................................................__________ g 

Mass of 5% MPA Diluent added to the 100 mL volumetric flask.................__________ g 

Calculated [TAA]DS2......................................................................................__________ μmol/L
	

DILUTE SOLUTION 3 

Mass of added stock solution (0.125 mL) ......................................................__________ g 

Mass of 5% MPA Diluent added to the 100 mL volumetric flask .................__________ g 

Calculated [TAA]DS3......................................................................................__________ μmol/L
	

Please return by March 15, 2010 

MMQAP Fax: 301-977-0685 

100 Bureau Drive, Stop 8392 Email: david.duewer@nist.gov 

Gaithersburg, MD 20899-8392 

E5
 

 

 

 

 

 

 

 

 

 

 

Participant #: Date: 

Vitamin C Round Robin 32 

NIST Micronutrient Measurement Quality Assurance Program
 

Analysis of Control Materials and Test Samples
 

Sample Replicate 1 Replicate 2 Units
 

Dilute Solution 1 μmol/L of Dilute Solution 

Dilute Solution 2 μmol/L of Dilute Solution 

Dilute Solution 3 μmol/L of Dilute Solution 

5% MPA Diluent μmol/L of Diluent 

μmol/L of Sample CS #1 Target: 8.4 ±1.8 μmol/L 

Serum Test Sample #321 μmol/L of Sample 

Serum Test Sample #322 μmol/L of Sample 

Serum Test Sample #323 μmol/L of Sample 

Serum Test Sample #324 μmol/L of Sample 

Were samples frozen upon receipt? Yes | No 

Analysis method: HPLC-EC | HPLC-Fluor DAB | HPLC-OPD | HPLC-UV | AO-OPD | Other 

If “Other”, please describe: 

COMMENTS: 

Please return by March 15, 2010 

MMQAP Fax: 301-977-0685 

100 Bureau Drive, Stop 8392 Email: david.duewer@nist.gov 

Gaithersburg, MD 20899-8392 

E6
 

 

 

 

Participant #: ________ Date: _____________ 

Vitamin C Round Robin 32
 

NIST Micronutrients Measurement Quality Assurance Program
 

Packing List and Shipment Receipt Confirmation Form
 

This box contains one vial each of the following six VitC M2QAP samples:
 

Label Form
 

VitC #321 Liquid frozen (1:1 serum:10% MPA) 

VitC #322 Liquid frozen (1:1 serum:10% MPA) 

VitC #323 Liquid frozen (1:1 serum:10% MPA) 

VitC #324 Liquid frozen (1:1 serum:10% MPA) 

CS #2 Liquid frozen (1:1 serum:10% MPA) 

Control Solid AA 

Please 1) Open the pack immediately 

2) Check that it contains one vial each of the above samples 

3) Check if the samples arrived frozen 

4) Store the samples at -20  ̊C or below until analysis 

5) Complete the following information 

6) Fax the completed form to us at 301-977-0685 

(or email requested information to david.duewer@nist.gov) 

1) Date this shipment arrived: ___________________________ 

2) Are all of the vials intact? Yes | No 

If "No", which one(s) were damaged? 

3) Was there any dry-ice left in cooler? Yes | No 

4) Did the samples arrive frozen? Yes | No 

5) At what temperature are you storing the samples? _______  ̊C 

6) When do you anticipate analyzing these samples? ________________________ 

Your prompt return of this information is appreciated. 

The M2QAP Gang 

Mail: M2QAP 

NIST, Stop 8392 Fax: 301-977-0685 

Gaithersburg, MD 20899-8392 Email: David.Duewer@NIST.gov 

E7
 

 

Appendix F. Final Report for RR32 

The following two pages are the final report as provided to all participants: 

•	 Cover letter. 

•	 An information sheet that: 

o	 describes the contents of the “All-Lab” report, 

o	 describes the content of the “Individualized” report, 

o	 describes the nature of the test samples and details their previous distributions, 

if any, and 

o	 summarizes aspects of the study that we believe may be of interest to the 

participants. 

F1
April 27, 2010 

Dear Colleague: 

UNn'ED STATES DEPARTMENT OF COMMERCE 

National Institute of Standards and Technolagy 

Gaithersburg, Maryland 20899-

Enclosed is the summary report for Round Robin 32 (RR32) for the measurement of total 

ascorbic acid (T AA, ascorbic acid plus dehydroascorbic acid) in human serum. Included in this 

report are a summary of data for all laboratories and an individualized summary of your 

laboratory's measurement performance. The robust median is used to estimate the consensus 

value for all samples, the "median absolute deviation from the median" (MADe) is used to 

estimate the expected standard deviation, and the coefficient of variation (CV) is defined as 

1 OOxMADe/median. 

RR32 consisted of four test samples (#321, #322, #323, and #324), one serum control material 

(CS#2), and one solid control material for preparation ofTAA control solutions. Details 

regarding the samples can be found in the enclosed report. 

If you have concerns regarding your laboratory's performance, we suggest that you obtain and 

analyze a unit of Standard Reference Material (SRM) 970, Vitamin C in Frozen Human Serum. 

SRM 970 can be purchased from the NIST SRM Program at phone: 301-975-6776; fax: 

301-948-3 730. If your measured values do not agree with the certified values, we suggest that 

you contact us for consultation. 

Samples for the second vitamin C round robin (RR33) of the 2010 Micronutrients Measurement 

Quality Assurance Program (M2

QAP) will be shipped during the week of June 7, 2010. 

If you have questions or concerns regarding this report, please contact David Duewer at 

301-975-3935; e-mail: david.duewer@nist.gov or me at 301-975-3120; e-mail: 

jbthomas@nist.gov; or fax: 301-977-0685. 

Sincerely, 

eanice Brown Thomas 

Research Chemist 

Analytical Chemistry Division 

Chemical Science and Technology Laboratory 

Laboratory 

Enclosures 

Cc: L. C. Sander 

David L. Duewer 

Research Chemometrician 

Analytical Chemistry Division 

Chemical Science and Technology 

NISI 

F2
 

The NIST M2QAP Vitamin C Round Robin 32 (RR32) report consists of 

Page “Individualized” Report 

1 Summarizes your reported values for the nominal 55 mmol/L solution you prepared from the 

ascorbic acid solid control sample, the serum control sample, and the four serum test 

samples. 

2 Graphical summary of your RR32 sample measurements. 

Page “All Lab” Report 

1 A tabulation of results and summary statistics for Total Ascorbic Acid [TAA] in the RR32 

samples and control/calibration solutions. 

Serum-based Samples. One serum control and four unknowns were distributed in RR32. 

CS#2 SRM 970 level 2, ampuled in mid-1998. 

S32:1 Serum 321, ampuled in late 2001, previously distributed as: S17:1 (RR17, Fall 02), S19:2 

(RR19, Fall 03), S21:2 (RR21, Fall 04), S22:1 (RR22, Spring 05), S24:1 (RR24, Spring 06), 

S28:1 (RR28, Spring 07), S30:1 (RR30, Spring 08). 

S32:2 Serum 322, ampuled in Fall 2009, initial distribution 

S32:3 Serum 323, ampuled in Fall 2009, initial distribution 

S32:4 Serum 324, ampuled in Fall 2009, initial distribution 

Results. 

1)	 All participants who prepared the four 5% MPA control/calibration solutions (the three “Dilute 

Solutions” and the “Diluent”) did so correctly. The criteria used to evaluate this success are: the 

density of the 5% MPA (≈1.03 gm/mL), the observed wavelength maximum of “Dilute Solution 

#1”(≈244 nm), the observed absorbance at that maximum (≈0.58 OD), the calculated E1% #1”(≈560 

dL/g·cm). 

2)	 The Measured = a+b*Gravimetric calibration parameters for the control/calibration solutions 

(columns 10 to 13 of the All Lab Report) indicate that the measurement systems for all participants 

are linear (R2

 close to 1 and RMS close to 0.0) and reasonably well calibrated (intercepts range from 

-0.5 to 1.7 and slopes range from 0.92 to 1.07). 

3)	 The Measured = p+q*Median regression parameters for samples S32:1 to S32:4 confirm the linearity 

of most measurement systems (R2 close to 1 and RMS close to 0.0). 

4)	 There is no evidence of sample degradation in the CS#2 (ampuled in 1998) or S32:1 (ampuled in 

2001) materials. 

5)	 This was the first distribution of the S32:2, S32.3, and S32:4 materials. There were no reported 

issues in their analysis. The observed 8 % and 5 % relative standard deviations for the S32:2 and 

S32:3 are at or lower than the 8 % expected from past studies; the 11% is higher than expected but 

well “within the noise” given the number of participants. 

F3
Appendix G. “All-Lab Report” for RR32 

The following single page is the “All-Lab Report” as provided to all participants, with 

two exceptions: 

• the participant identifiers (Lab) have been altered. 

• the order in which the participant results are listed has been altered. 

The data summary in the “All-Lab Report” has been altered to ensure confidentiality of 

identification codes assigned to laboratories. 

G1
 

 

 

Micronutrients Measurement Quality Assurance Program for Total Ascorbic Aci

"Round Robin" 32 - March 2010 

Control / Calibration Samples MPA Dilute Solution 1 

Measured = a + b*Grav Density Spectrophotometry Measured, μmo

Grav, μmol/L Measured, μmol/L 

E1% Lab Date Dil:1 Dil:2 Dil:3 Dil:1 Dil:2 Dil:3 MPA Inter Slope R2 RMS g/mL CS#2 S32:1 S32:2 S3

λmax Amax 

VC-MA 24/02/10 59.0 29.8 14.8 60.9 31.5 15.8 0.0 0.34 1.03 1.000 0.5 1.034 242. 0.5660 545.1 28.8 9.2 26.1 

VC-MB 13/01/10 56.7 28.0 14.2 57.6 32.0 15.0 0.0 0.94 1.02 0.995 2.1 1.031 244. 0.5560 556.4 28.4 9.3 22.5 

VC-MC 25/03/10 58.3 29.3 14.5 57.5 28.0 14.2 0.0 -0.21 0.98 1.000 0.5 1.023 243. 0.5643 549.5 28.9 9.6 25.3 

VC-ME 02/03/10 57.2 28.5 14.5 57.4 28.8 14.4 0.0 -0.01 1.00 1.000 0.1 1.032 244. 0.5552 551.3 26.0 8.3 19.0 2

VC-MG 25/02/10 58.7 29.6 14.7 62.5 30.7 14.9 0.0 -0.45 1.07 1.000 0.5 1.028 243.7 0.5890 570.0 28.3 8.7 23.5 

VC-MH 07/02/10 62.1 31.6 14.8 61.8 31.0 14.8 0.0 -0.07 0.99 1.000 0.3 1.031 244.1 0.6121 559.9 28.1 9.7 24.0 

VC-MI 25/02/10 55.3 27.7 13.9 56.6 27.5 14.5 0.0 -0.05 1.02 1.000 0.6 1.030 28.5 8.9 24.1 

VC-MJ 10/03/10 61.5 30.7 15.4 63.4 32.6 17.0 1.7 1.67 1.00 1.000 0.2 1.019 254a 0.373a 344.5a 31.3 14.4 29.9 

VC-MN 05/03/10 58.5 28.4 14.0 54.2 27.0 12.8 0.0 0.06 0.93 1.000 0.5 1.029 243.6 0.6181 599.6 28.2 11.8 24.6 

VC-MP 20/01/10 28.2 9.0 24.3 

VC-MU 18/02/10 25.6 b 19.0 2

VC-NE 10/02/10 57.6 29.0 14.2 58.3 28.8 14.2 0.0 -0.16 1.01 1.000 0.3 1.034 244. 0.5840 575.2 28.8 9.6 25.4 

VC-NF 08/03/10 56.6 28.5 14.0 58.8 30.4 14.5 0.2 0.23 1.04 1.000 0.5 1.030 243. 0.5610 562.4 27.7 9.8 23.3 

G2

N 11 11 11 11 11 11 11 

58.3 29.2 14.5 59.0 29.8 14.7 0.2 

2.0 1.2 0.5 2.8 1.9 1.0 0.5 

N 11 9 9 9 13 12 13 

Average Average 1.029 243.5 0.5784 563.3 28.2 9.9 23.9 

SD SD 0.004 0.7 0.0238 16.7 1.4 1.7 2.8 

Min 55.3 27.66 13.9 

57.0 28.46 14.1 

58.3 29.04 14.5 

58.8 29.68 14.8 

62.1 31.60 15.4 

1.7 0.9 0.5 

3 3 3 

54.2 26.97 12.8 0.0 

57.4 28.38 14.3 0.0 

58.3 30.41 14.5 0.0 

61.3 31.26 14.9 0.0 

63.4 32.62 17.0 1.7 

2.5 2.4 0.5 0.0 

4 8 4 

Min 1.019 242.0 0.5552 545.1 25.6 8.3 19.0 

%25 %25 1.028 243.0 0.5610 551.3 28.1 9.0 23.3 

Median Median 1.030 243.7 0.5660 559.9 28.3 9.4 24.1 

%75 %75 1.032 244.0 0.5890 570.0 28.8 9.7 25.3 

Max Max 1.034 244.1 0.6181 599.6 31.3 14.4 29.9 

MADe eSD 0.003 0.4 0.0160 15.0 0.8 0.6 1.8 

CV CV 0.29 0.18 2.8 2.7 3 6 8 

a ) 5% Trichloroacetic acid solution 

b ) Mislabeled sample 

All Lab Report 
Appendix H. Representative “Individualized Report” for RR32 

Each participant in RR32 received an “Individualized Report” reflecting their reported 

results. The following two pages are the “Individualized Report” for participant 

“VC-MA”. 

H1
 

 Set 1 of 15 

Vitamin C "Round Robin" 32 Report: Participant VC-MA
 

MPA Dilute Solution 1 Control/Calibration Solutions 

Density Spectrophotometry Ymeas = Inter + Slope* Xgrav 

Date RR Method 

10/05/07 27 HPLC-EC 

03/04/08 28 HPLC-EC 

08/11/08 29 HPLC-EC 

03/03/09 30 HPLC-EC 

09/10/09 31 HPLC-EC 

02/24/10 32 HPLC-EC 

g/mL 

1.032 

1.035 

1.037 

1.037 

1.036 

1.035 

λmax Amax E1% Inter Slope R2 SEE 

242.0 0.561 557.2 -0.1 0.99 1.000 0.14 

243.0 0.572 562.2 0.7 1.03 0.999 0.99 

243.0 0.567 553.2 0.3 1.03 1.000 0.64 

242.0 0.569 555.6 0.2 1.03 1.000 0.40 

244.0 0.566 546.1 -0.1 1.02 1.000 0.20 

242.0 0.566 545.1 0.3 1.03 1.000 0.46 

Mean 1.035 242.7 0.57 553.2 Pooled SEE 0.55 

SD 0.002 0.8 0.00 6.6 

CV 0.16 0.34 0.6 1.2 

[TAA] mmol/Lsample 

Date RR Sample Rep1 Rep2 Fadj Mean SDdup N Mean SDrepeat SDreprod 

02/23/04 20 CS#2 25.8 26.2 

09/13/04 21 CS#2 26.2 27.2 

03/08/05 22 CS#2 29.0 29.0 

10/17/05 23 CS#2 29.4 30.5 

03/09/06 24 CS#2 29.2 29.1 

08/28/06 25 CS#2 27.2 28.1 

10/05/07 27 CS#2 28.1 27.4 

08/11/08 29 CS#2 27.2 27.2 

09/10/09 31 CS#2 31.8 32.2 

02/24/10 32 CS#2 28.6 29.0 

1.0 26.0 0.3 10 28.4 0.5 1.7 

1.0 26.7 0.7 

1.0 29.0 0.0 

1.0 30.0 0.8 

1.0 29.2 0.1 

1.0 27.6 0.6 

1.0 27.7 0.5 

1.0 27.2 0.0 

1.0 32.0 0.3 

1.0 28.8 0.3 

12/12/02 17 S17:1 9.9 9.1 

11/13/03 19 S19:2 9.2 9.1 

09/13/04 21 S21:2 8.8 8.7 

03/08/05 22 S22:1 9.6 9.6 

03/09/06 24 S24:1 9.8 9.6 

03/04/08 28 S28:1 10.4 10.3 

03/03/09 30 S30:1 9.5 9.4 

02/24/10 32 S32:1 9.5 8.9 

02/24/10 32 S32:2 26.2 26.0 

02/24/10 32 S32:3 33.4 32.8 

02/24/10 32 S32:4 49.0 48.6 

Please check our records against your records.

Micronutrients Measurement Quality Assurance Program 

National Institute of Standards and Technology 

100 Bureau Drive Stop 8392 

Gaithersburg, MD 20899-8392 USA 

1.0 9.5 0.6 8 9.5 0.3 0.5 

1.0 9.2 0.1 

1.0 8.7 0.1 

1.0 9.6 0.0 

1.0 9.7 0.2 

1.0 10.4 0.1 

1.0 9.4 0.1 

1.0 9.2 0.5 

1.0 26.1 0.1 

1.0 33.1 0.5 

1.0 48.8 0.3 

 Send corrections and/or updates to... 

Fax: (301) 977-0685 

Email: david.duewer@nist.gov 

Individualized Report Page 1/2 

H2
 

NIST, RR 22

H3

 Set 1 of 15 

Vitamin C "Round Robin" 32 Report: Participant VC-MA 

Total Ascorbic Acid, μmol/mL 

[Total Ascorbic Acid], μmol/L 

0 

S17:1S19:2 S21:2S22:1 S24:1 Apparent Precision, SD S28:1S30:1S32:2S32:3S32:4

Your [Total Ascorbic Acid], μmol/L 

Median [Total Ascorbic Acid], μmol/L 

Concordance, SD 

3rd Quartile (75%) You, this RR Median (50%) You, past RRs Others, this RR 1st Quartile (25%) 

For details of the construction and interpretation of these plots, see: 

Duewer, Kline, Sharpless, Brown Thomas, Gary, Sowell. Anal Chem 1999;71(9):1870-8. 

Sample Comments 

S32:1 VitC #321 previously distributed in RRs 17, 19, 21, 22, 24, 28, 30 

S32:2 VitC #322, first distribution 

S32:3 VitC #323, first distribution 

S32:4 VitC #324, first distribution 

Individualized Report page 2/2