NISTIR 7880-17 

NIST Micronutrients Measurement 

Quality Assurance Program 

Winter 2004 

Comparability Studies 

Results for Round Robin LV 

Fat-Soluble Vitamins and Carotenoids in Human Serum 

and Round Robin 20 Ascorbic Acid in Human Serum 

David L. Duewer 

Jeanice B. Thomas 

 

 

 

 

NISTIR 7880-17
 

NIST Micronutrients Measurement 

Quality Assurance Program 

Winter 2004 

Comparability Studies 

Results for Round Robin LV 

Fat-Soluble Vitamins and Carotenoids in Human Serum 

and Round Robin 20 Ascorbic Acid in Human Serum 

David L. Duewer 

Jeanice B. Thomas 

Chemical Sciences Division 

Materials Measurement Laboratory 

-XQH 2013 

U.S. Department of Commerce 

&DPHURQ).HUU\, 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 2004 MMQAP measurement comparability improvement studies: 1) Round Robin LV FatSoluble Vitamins and Carotenoids in Human Serum and 2) Round Robin 20 Total Ascorbic Acid in 

Human Serum. The materials for both studies were shipped to participants in November 2003; 

participants were requested to provide their measurement results by March 5, 2004. 

Keywords 

Human Serum
 

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

Total Ascorbic Acid
 

iii 
 

 

 

 

 

 

 

 

Table of Contents 

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

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

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

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

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

Round Robin 20: Vitamin C in Human Serum............................................................................... 2
 

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

Appendix A. Shipping Package Inserts for RR55........................................................................ A1
 

Appendix B. Final Report for RR55 ..............................................................................................B1
 

Appendix C. “All-Lab Report” for RR55 ......................................................................................C1
 

Appendix D. Representative “Individualized Report” for RR55 ............................................... D1
 

Appendix E. Shipping Package Inserts for RR20 ......................................................................... E1
 

Appendix F. Final Report for RR20............................................................................................... F1
 

Appendix G. “All-Lab Report” for RR20..................................................................................... G1
 

Appendix H. Representative “Individualized Report” for RR20............................................... 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 LV: Fat-Soluble Vitamins and Carotenoids in Human Serum 

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

LV comparability study (hereafter referred to as RR55) received two lyophilized and three 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 

November 2003. 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 RR55 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 20: Vitamin C in Human Serum 

Participants in the MMQAP Vitamin C in Human Serum Round Robin 20 comparability study 

(hereafter referred to as RR20) received four frozen serum test samples, two frozen control sera, 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 November 2003. 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 RR20 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 RR55 

The following three items were included in each package shipped to an RR55 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
November 17, 2003 

Dear Colleague: 

UNITED STATES DEPARTMENT OF COMMERCE 

National Institute of Standards and Technology 

Gaithersburg, Maryland 20899-0001 

Enclosed are the samples (Sera 299 - 303) for the first fat-soluble vitamins and carotenoids in setum 

round robin study (Round Robin L V) for the 2004 NIST Micronutrients Measurement Quality Assurance 

Program. You will find one vial of each of three liquid-frozen and two lyophilized serum samples for 

analysis along with a form for reporting your results. When reporting your results, please submit one 

value for each analyte for a given serum sample. If a value is obtained below your limit of quantification, 

please indicate this result on the form by using NQ (Not Quantified). Results are due to NIST by March 

5, 2004. Results received more than two weeks after the due date will not be included in the summary 

report for this round robin study. The feedback report concerning the study will be provided around midOctober. 

Lyophilized samples should be reconstituted with 1.0 ml of HPLC-grade water or equivalent. We 

recommend that dissolution be facilitated with 3 to 5 min agitation in an ultrasonic bath or at least 30 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.) 

Pipette a known volume of serum from the vial for analysis. The final volume of the reconstituted sample 

is greater than 1.0 mL. Water should not be added to the liquid-frozen samples 301, 302, and 303. 

For consistency, we request that laboratories use the following absorptivities (E 1 % cm): retinal, 1843 at 

325 nm (ethanol); retinyl palmitat~, 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); P-carotene, 2560 at 450 nm 

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

Please mail or fax your results for Round Robin LV to: 

esearch Chemist 

Analytical Chemistry· Division 

Micronutrients J\1easurement Quality Assurance Program 

NIST 

100 Bureau Drive Stop 8392 

Gaithersburg, MD 20899-8392 

Fax: (301) 977-0685 

Chemical Science and Technology Laboratory 

Enclosures 

NISI 

A2
 

 

 

Participant #: ________ Date: _____________ 

Round Robin LV 

NIST Micronutrients Measurement Quality Assurance Program 

Analyte 299 300 301 302 303 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 analytes? 

* we prefer μg/mL 

Were sera {301,302,303} frozen when received? Yes | No 

Comments: 

Mail: M2QAP 

NIST, Stop 8392 Please return results before Fax: 301-977-0685 

Gaithersburg, MD 20899-8392 5-Mar-2004 Email: David.Duewer@NIST.gov 

A3
 

 

 

 

Participant #: ________ Date: _____________ 

Fat-Soluble Vitamins Round Robin LV 

NIST Micronutrients Measurement Quality Assurance Program 

Packing List and Shipment Receipt Confirmation Form 

This box contains (we hope) one vial each of the following five FSV M2QAP sera: 

Serum Form Reconstitute? 

#299 Lyophilized Yes (1 ml H2O) 

#300 Lyophilized Yes (1 ml H2O) 

#301 Liquid frozen No 

#302 Liquid frozen No 

#303 Liquid frozen No 

Please 1) Open the pack immediately 

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

3) Check if sera {301, 302, 303} 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 five vials intact? Yes | No 

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

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

4) Did sera {301, 302, 303} 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 

A4
 

 

Appendix B. Final Report for RR55 

The following three 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
May 6, 2004 

Dear Colleague: 

UNITED STATES DEPARTMENT OF COMMERCE 

National Institute of Standards and Technology 

Gaithersburg, Maryland 20899-0001 

Enclosed is the summary report of the results forthe first round robin (RR 55) of the 2004 NIST 

Micronutrients Measurement Quality Assurance Program (M2

QAP) for 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 comparabilities relative to the NIST assigned values. For RR 

55 only, the NIST-assigned values are the interlaboratory ~omparison exercise medians. 

Data for evaluating laboratory performance in RR 55 are provided in the comparability summary (Score 

Card) on page 6 of the All Lab Report. Laboratory comparability is summarized as follows: results rated 

1 to 3 are within 1 to 3 standard deviation(s) of the assigned value, respectively; those rated 4 are >3 

standard deviations from the assigned value. 

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

unit of SRM 968c, Fat-Soluble Vitamins, Carotenoids, and Cholesterol in Human Serum. If your 

measured values do not agree with the certified values, we suggest that you contact us for consultation. 

There were more than 40 attendees at the Micronutrients Measurement Quality Assurance Workshop, 

which was held at the Experimental Biology '04 meeting on April 21. A summary of the workshop will 

be sent in a future mailing. 

Samples for the second 2004 QA interlaboratory exercises will be shipped during the week of May 17. 

If you have any questions regarding this report, please contact Dave Duewer at david.duewer@nist.gov 

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

Je ice Brown Thomas 

R search Chemist 

A 1 alytical Chemistry Division 

hemical Science and Technology Laboratory 

Enclosures 

B2
 

 

The NIST M2QAP Round Robin LIV (RR55) report consists of: 

Page 

1-4 A listing of all results and statistics for analytes reported by at least two laboratories. 

5a A list of results for the seven analytes reported by only one laboratory. 

5b A legend for the above two lists. 

6 The text version of the “Comparability Summary” (or “Score Card”). 

Page “Individualized” Report 

1 

2 to 

n 

n+1 

Samples.

Serum 

299 

300 

301 

302 

303 

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 “target” plot version of your “Comparability Summary” scores. 

 The five sera below were distributed in RR55. 

Description	 Prior Distributions 

Lyophilized blended serum with native #249 in RR44 (9/98), #256 in RR46 (6/99), 

carotenoid levels, augmented with α- and δ- #264 in RR48 (3/01), #284 in RR52 (9/02)
 

tocopherol; SRM 968c Level II. 

Lyophilized, native, single donor, #290 in RR53 (2/03)
 

commercially obtained serum prepared in
 

2002. The same material was used to prepare 

#301. 

Fresh-frozen, native, single donor, #292 in RR53 (2/03)
 

commercially obtained serum prepared in
 

2002. The same material was used to prepare 

#300. 

Fresh-frozen, native, single-donor, #288 in RR52 (9/02), #293 in RR53 (2/03)
 

commercially obtained serum prepared in
 

2002. This material has rather low levels of
 

most micronutrients. 

Fresh-frozen single-donor hemolyzed serum #287 in RR52 (9/02)
 

with endogenous augmented carotenoid levels. 

A gift to the M2QAP from the CDC.
 

1)	 Sera Stability. There was no significant change in the median level nor increase in the variability of 

any measurand in any of the sera. For most measurands in most of the sera, there may be a small 

decrease in the variability... Since the sera are unlikely to improve with age, we may hope that this 

indicates a general improvement in measurement concordance among the participants. 

B3
2)	 Matrix (Lyophilized Vs Fresh-Frozen) Differences. Sera 300 and 301 were prepared from the same 

serum pool. Since we suggest that you reconstitute our lyophilized samples with 1.0 mL water rather 

than to a total volume of 1.0 mL, the measurand levels in Serum 300 should be ≈ 95% of those in 

Serum 301. The observed average ratio ±SD over all measurands with 10 or more quantitative 

measurements is 0.952 ±0.008. If any of your Sera300/301 ratios are much different than 0.95, you 

may want to take a hard look at your measurement system for those measurands. If your ratios are 

consistently much different from 0.95, you should review how you reconstitute lyophilized materials. 

3)	 Hemolysis. Serum 303 is somewhat hemolyzed. There was little or no increase in among-participant 

measurement variability for this serum; however, two participants reported chromatographic 

anomalies for α-tocopherol. If your results for this material are not consistent with those of the other 

four sera in RR55, you should evaluate the influence of sample hemolysis on your measurement 

system. 

B4
 

 

Appendix C. “All-Lab Report” for RR55 

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. The only attributed results are those 

reported by NIST. The NIST results are not used in the assessment of the consensus 

summary results of the study. 

C1
 

 

Round Robin LV Laboratory Results 

All values in μg/mL 

Total Retinol trans-Retinol Retinyl Palmitate α-Tocopherol γ/β-Tocophero

Lab 299 300 301 302 303 

C2

FSV-BA 0.505 0.626 0.662 0.343 0.645 

FSV-BB 0.474 0.607 0.610 0.323 0.617 

FSV-BD 0.473 0.567 0.601 0.288 0.588 

FSV-BE ≥0.48 ≥0.59 ≥0.63 ≥0.34 ≥0.62

FSV-BF 0.425 0.575 0.610 0.292 0.591 

FSV-BG 0.493 0.610 0.643 0.326 0.626 

FSV-BH 0.464 0.548 0.569 0.287 0.513 

FSV-BI 0.491 0.618 0.670 0.349 0.645 

FSV-BJ 0.482 0.583 0.581 0.315 0.608 

FSV-BK 0.517 - 0.656 0.358 0.690 

FSV-BL 0.490 0.690 0.720 0.370 0.690 

FSV-BM 0.477 0.607 0.646 0.352 0.621 

FSV-BN 0.461 0.589 0.650 0.323 0.600 

FSV-BO ≥0.453 ≥0.573 ≥0.647 ≥0.315 ≥0.590

FSV-BP 0.481 0.595 0.642 0.349 0.629 

FSV-BQ 0.548 0.763 0.726 0.373 0.689 

FSV-BR ≥0.478 ≥0.617 ≥0.625 ≥0.354 ≥0.590

FSV-BS 0.341 0.443 0.518 0.285 0.422 

FSV-BU 0.446 0.599 0.629 !0.382 0.601 

FSV-BV 0.473 0.569 0.616 0.323 0.585 

FSV-BW 0.440 0.580 0.630 0.330 0.600 

FSV-BX 0.485 0.597 0.646 0.329 0.600 

FSV-CB 0.467 0.521 0.556 0.268 0.513 

FSV-CC 0.460 0.590 0.620 0.320 0.580 

FSV-CD 0.484 0.606 0.654 0.341 0.624 

FSV-CE 0.470 0.670 0.600 0.270 0.490 

FSV-CF 0.520 0.631 0.660 0.390 0.626 

FSV-CG 0.529 0.634 0.638 0.329 0.618 

FSV-CI 0.467 0.613 0.632 0.365 0.625 

FSV-CS 0.487 0.656 0.665 0.353 0.675 

FSV-CT 

FSV-CW ≥0.413 ≥0.495 ≥0.517 ≥0.362 ≥0.489

FSV-CZ 0.530 0.560 0.630 0.310 0.560 

FSV-DA 0.473 0.608 0.643 0.333 0.590 

FSV-DF 0.497 0.566 0.628 0.318 0.591 

FSV-DI 0.481 0.606 0.636 0.329 0.628 

FSV-DW 0.540 0.540 0.650 0.340 0.610 

FSV-ET 0.470 0.600 0.630 0.310 0.600 

299 300 301 302 303 

0.480 0.590 0.630 0.340 0.620 

0.453 0.573 0.647 0.315 0.590 

0.478 0.617 0.625 0.354 0.590 

0.460 0.590 0.620 0.320 0.580 

0.413 0.495 0.517 0.362 0.489 

299 300 301 302 303 

0.097 0.117 0.127 0.023 0.039 

0.081 0.073 0.080 0.012 0.063 

0.085 0.092 0.202 0.034 0.049 

0.082 0.099 0.113 nd nd 

0.078 0.079 0.083 nq nq 

0.065 0.076 0.084 0.010 0.017 

0.087 0.105 0.113 0.016 0.023 

0.104 0.131 0.124 0.020 0.043 

0.066 0.069 0.075 0.013 0.024 

<0.010 0.020 0.027 0.034 0.026 

0.092 0.102 0.112 0.015 0.022 

0.078 0.088 0.098 0.015 0.022 

299 300 301 302 303 

16.44 9.70 10.34 2.90 13.4 

18.44 10.47 10.84 2.87 14.8 

16.50 8.60 9.30 2.40 12.6 

16.30 9.60 10.20 3.00 13.0 

15.99 9.99 10.84 2.97 14.3 

16.98 9.90 10.53 2.92 13.4 

16.93 10.08 10.30 2.75 11.9 

18.46 10.78 11.30 3.08 14.2 

16.47 9.51 9.46 2.82 13.6 

18.40 - 10.10 2.10 15.0 

15.50 10.34 10.34 3.01 -

17.00 10.60 11.30 3.10 13.1 

14.96 9.00 9.91 2.54 11.3 

15.68 8.96 9.56 2.64 11.9 

15.77 10.46 10.19 2.84 12.6 

15.80 10.30 9.80 2.60 12.0 

16.93 9.78 9.73 3.20 14.0 

16.69 10.06 10.69 !3.058 12.6 

15.93 9.18 9.94 2.96 12.3 

15.84 9.50 10.33 2.74 12.7 

16.66 9.62 10.50 2.84 !6.19 

16.85 9.78 10.68 3.03 11.8 

15.42 9.27 9.76 2.83 11.6 

16.86 9.25 10.11 2.47 12.8 

19.87 8.47 10.45 2.88 16.9 

17.30 10.30 10.90 3.10 13.7 

14.91 9.08 9.84 2.59 10.6 

15.73 9.19 9.55 2.55 11.5 

16.92 10.24 10.48 2.74 13.6 

15.30 8.60 8.70 2.60 10.8 

18.40 9.50 10.50 2.80 10.8 

17.12 10.28 10.82 2.93 11.5 

17.40 10.20 10.80 2.90 13.6 

15.50 8.50 11.66 3.40 14.0 

15.80 9.40 9.70 2.60 12.5 

299 300 301 302 

1.64 1.82 1.93 0.78

1.56 1.67 1.72 0.72

1.50 1.70 1.80 0.70

1.64 1.80 1.96 0.68

1.59 1.70 1.79 0.72

1.76 1.87 1.98 0.79

1.54 1.61 1.57 0.68

1.46 1.67 1.85 0.71

1.38 1.47 1.70 0.65

1.57 1.80 1.97 !0.78

1.56 1.69 1.84 0.74

1.38 1.61 1.74 0.67

1.52 1.70 1.77 0.71

1.56 1.58 1.77 0.66

1.60 1.76 1.89 0.73

1.45 1.60 1.66 0.62

1.55 1.70 1.76 0.74

1.60 1.70 1.70 0.80

1.66 1.89 1.97 0.73

1.57 1.73 1.82 0.71

1.60 1.80 1.90 0.70

N 33 32 33 32 33 5 5 5 5 5 11 12 12 10 10 35 34 35 34 33 21 21 21 2

Min 0.341 0.443 0.518 0.268 0.422 0.413 0.495 0.517 0.315 0.489 0.065 0.020 0.027 0.010 0.017 14.91 8.47 8.70 2.10 10.6 1.38 1.47 1.57 0.62

Median 0.481 0.600 0.636 0.329 0.608 0.460 0.590 0.625 0.340 0.590 0.082 0.090 0.105 0.016 0.025 16.50 9.66 10.33 2.84 12.7 1.56 1.70 1.80 0.71

Max 0.548 0.763 0.726 0.390 0.690 0.480 0.617 0.647 0.362 0.620 0.104 0.131 0.202 0.034 0.063 19.87 10.78 11.66 3.40 16.9 1.76 1.89 1.98 0.80

SD 0.024 0.030 0.032 0.026 0.030 0.023 0.030 0.031 0.025 0.030 0.009 0.020 0.025 0.007 0.015 0.89 0.76 0.64 0.27 1.3 0.08 0.10 0.12 0.03

CV 5 5 5 8 5 5 5 5 7 5 10 22 24 43 59 5 8 6 9 10 5 6 7 

Npast 44 33 33 36 38 8 9 9 7 5 15 13 13 10 9 47 38 38 39 39 26 22 22 2

Medianpast 0.482 0.602 0.639 0.326 0.606 0.486 0.620 0.670 0.332 0.616 0.080 0.100 0.100 0.017 0.028 16.64 10.03 10.62 2.93 13.2 1.58 1.80 1.90 0.73

SDpast 0.039 0.038 0.055 0.029 0.068 0.043 0.035 0.034 0.017 0.031 0.019 0.020 0.022 0.006 0.008 1.36 0.73 0.77 0.31 1.1 0.13 0.12 0.17 0.08

NIST 0.492 0.629 0.680 0.350 0.624 0.485 0.627 0.680 0.350 0.615 16.99 10.09 10.59 2.85 12.6 1.55 1.73 1.78 0.70

NAV 0.481 0.600 0.632 0.329 0.608 0.469 0.590 0.628 0.341 0.590 0.084 0.092 0.112 0.016 0.026 16.58 9.70 10.33 2.84 12.7 1.57 1.70 1.79 0.71

NAU 0.039 0.048 0.050 0.028 0.048 0.038 0.047 0.050 0.028 0.047 0.023 0.025 0.029 0.011 0.015 1.29 0.76 0.80 0.40 1.3 0.17 0.18 0.19 0.09

All Lab Report 
 

 

Round Robin LV Laboratory Results 

All values in μg/mL 

Total β-Carotene trans-β-Carotene Total cis-β-Carotene Total α-Carotene 

C3

Lab 299 300 301 302 303 299 300 301 302 303 299 300 301 302 303 299 300 301 302 303 299 

FSV-BA 0.435 0.121 0.129 0.051 1.537 0.408 0.115 0.124 0.051 1.474 0.028 0.006 0.005 0.002 0.062 0.088 0.069 0.073 0.005 0.031 

FSV-BB 0.432 0.098 0.109 0.048 1.462 0.400 0.098 0.109 0.048 1.392 0.031 0.004 0.005 0.002 0.070 0.091 0.058 0.067 0.004 0.037 0.408 

FSV-BD 

FSV-BE 0.440 0.130 0.120 0.050 1.530
 

FSV-BF
 0.421 0.122 0.140 0.062 1.811 0.111 0.093 0.105 0.020 0.033 0.403 

FSV-BG 0.481 0.151 0.162 0.065 1.598 0.102 0.076 0.086 0.011 0.036 0.446 

FSV-BH 0.413 0.105 0.110 0.044 1.223 0.389 0.105 0.110 0.044 1.167 0.024 nq nq nq 0.057 0.080 0.063 0.066 nq nq 0.415 

FSV-BI 0.460 0.127 0.135 0.056 1.490 0.092 0.071 0.078 nd 0.031 0.360 

FSV-BJ 0.483 0.113 0.118 0.054 1.613 0.116 0.083 0.081 nq 0.028 0.504 

FSV-BK 

FSV-BL 

FSV-BM 

FSV-BN 0.415 0.104 0.113 0.042 1.397 0.377 0.104 0.113 0.042 1.316 0.038 nq nd nd 0.082 0.091 0.072 0.079 nq 0.023 0.369 

FSV-BO 0.440 0.098 0.103 0.044 1.574 0.088 0.068 0.068 nq 0.027 0.394 

FSV-BP 0.416 0.140 0.131 0.050 1.465 0.077 0.063 0.062 0.006 0.029 0.431 

FSV-BQ 

FSV-BR 

FSV-BS ≥0.352 ≥0.138 ≥0.122 ≥0.046 ≥1.371 0.352 0.138 0.122 0.046 1.371 0.081 0.091 0.079 0.001 0.030 0.412 

FSV-BU 0.416 0.135 0.134 !0.073 1.559 0.089 0.070 0.072 !0.0112 0.029 0.395 

FSV-BV 0.400 0.108 0.114 0.049 1.361 0.067 0.054 0.058 0.005 0.022 0.420 

FSV-BW 0.430 0.102 0.111 0.040 1.580 0.105 0.094 0.103 nq nq 0.440 

FSV-BX ≥0.405 ≥0.112 ≥0.122 ≥0.051 ≥1.242 0.405 0.112 0.122 0.051 1.242 0.107 0.079 0.081 0.006 0.028 

FSV-CB 0.464 0.118 0.133 0.056 1.592 0.074 0.054 0.061 0.004 0.018 0.336 

FSV-CC 

FSV-CD 0.428 0.103 0.105 0.044 1.353 0.125 0.096 0.096 nd 0.037 0.454 

FSV-CE 0.800 0.080 0.150 0.070 3.250 

FSV-CF 

FSV-CG 0.374 0.104 0.113 0.044 1.240 0.343 0.098 0.107 0.041 1.164 0.031 0.005 0.006 0.003 0.077 0.109 0.084 0.091 0.005 0.036 0.408 

FSV-CI ≥0.440 ≥0.097 ≥0.095 ≥0.036 ≥1.240 0.440 0.097 0.095 0.036 1.240 0.089 0.061 0.059 <0.016 0.022 

FSV-CS 0.446 0.126 0.127 0.054 1.409 0.405 0.116 0.119 0.049 1.300 0.043 0.009 0.009 0.005 0.108 0.100 0.079 0.080 0.005 0.030 0.504 

FSV-CT 0.331 0.079 0.089 0.035 1.425 0.371 

FSV-CW ≥0.340 ≥0.099 ≥0.101 ≥0.056 ≥1.091 0.340 0.099 0.101 0.056 1.091 0.086 0.067 0.068 <0.007 0.029
 

FSV-CZ
 0.490 0.160 0.180 0.004 1.150 

FSV-DA 0.425 0.121 0.129 0.057 1.343 0.383 0.115 0.121 0.052 1.270 0.042 0.007 0.007 0.005 0.075 0.097 0.077 0.082 0.006 0.028 0.425 

FSV-DF 

FSV-DI 0.456 0.108 0.120 0.046 1.489 0.413 

FSV-DW 0.320 0.050 0.130 0.090 1.100 0.300 

FSV-ET 0.410 0.110 0.110 0.050 1.440 

N 25 25 25 24 25 11 11 11 11 11 7 5 5 5 7 22 22 22 12 20 21 

Min 0.320 0.050 0.089 0.004 1.100 0.340 0.097 0.095 0.036 1.091 0.024 0.004 0.005 0.002 0.057 0.067 0.054 0.058 0.001 0.018 0.300 

Median 0.430 0.110 0.120 0.050 1.465 0.389 0.105 0.113 0.048 1.270 0.031 0.006 0.006 0.003 0.075 0.091 0.072 0.078 0.005 0.029 0.412 

Max 0.800 0.160 0.180 0.090 3.250 0.440 0.138 0.124 0.056 1.474 0.043 0.009 0.009 0.005 0.108 0.125 0.096 0.105 0.020 0.037 0.504 

SD 0.030 0.017 0.016 0.009 0.158 0.030 0.012 0.010 0.006 0.104 0.008 0.001 0.002 0.002 0.010 0.013 0.013 0.011 0.001 0.003 0.027 

CV 7 16 13 17 11 8 11 9 12 8 25 19 29 69 13 15 19 14 17 10 7 

Npast 32 27 27 28 27 15 14 14 13 13 10 8 8 7 9 27 23 23 17 22 26 

Medianpast 0.422 0.113 0.119 0.050 1.405 0.385 0.110 0.118 0.048 1.330 0.030 0.007 0.008 0.003 0.073 0.097 0.070 0.074 0.005 0.030 0.410 

SDpast 0.050 0.010 0.019 0.008 0.163 0.034 0.008 0.013 0.006 0.134 0.009 0.003 0.002 0.002 0.010 0.019 0.011 0.014 0.004 0.008 0.072 

NIST 

NAV 

NAU 

0.454 0.112 0.116 0.050 1.488 0.426 0.112 0.115 0.050 1.509 0.043 nd 0.002 nd 0.083 0.085 0.083 0.081 0.004 0.035 0.472 

0.431 0.112 0.124 0.050 1.477 

0.061 0.019 0.020 0.011 0.189 

0.395 0.108 0.115 0.049 1.256 

0.042 0.014 0.014 0.009 0.129 

0.031 0.006 0.006 0.003 0.072 

0.011 0.003 0.003 0.003 0.032 

0.091 0.071 0.078 0.005 0.029 

0.026 0.021 0.023 0.003 0.010 

0.413 

0.088 

All Lab Report 
 

 

Round Robin LV Laboratory Results 

All values in μg/mL 

trans-Lycopene Total β-Cryptoxanthin Total α-Cryptoxanthin Total Lutein Total Zeaxanthin 

Lab 299 300 301 302 303 

C4

FSV-BA 0.217 0.269 0.293 0.101 0.220 

FSV-BB 0.177 0.209 0.226 0.083 0.176 

FSV-BD 

FSV-BE 

FSV-BF 

FSV-BG 0.219 0.288 0.352 0.110 0.229 

FSV-BH 

FSV-BI 

FSV-BJ 

FSV-BK 

FSV-BL 

FSV-BM 

FSV-BN 0.192 0.240 0.279 0.090 0.182 

FSV-BO 

FSV-BP 

FSV-BQ 

FSV-BR 

FSV-BS 

FSV-BU 

FSV-BV 

FSV-BW 

FSV-BX 0.179 0.227 0.242 0.083 0.141 

FSV-CB 

FSV-CC 

FSV-CD 

FSV-CE 

FSV-CF 

FSV-CG 0.217 0.266 0.293 0.096 0.197 

FSV-CI 

FSV-CS 

FSV-CT 

FSV-CW 0.167 0.208 0.218 0.096 0.151 

FSV-CZ 

FSV-DA 0.221 0.287 0.306 0.109 0.203 

FSV-DF 

FSV-DI 

FSV-DW 

FSV-ET 

299 300 301 302 303 

0.040 0.063 0.068 0.023 0.125 

0.031 0.048 0.051 0.018 0.104 

0.022 0.041 0.049 0.015 0.106 

0.035 0.054 0.065 0.019 0.127 

0.043 0.068 0.069 0.020 0.131 

0.031 0.060 0.064 0.019 0.129 

0.030 0.057 0.059 0.021 0.127 

0.024 0.050 0.056 0.012 0.112 

0.028 0.051 0.049 0.015 0.097 

0.031 0.052 0.052 0.019 0.103 

0.030 0.064 0.058 0.011 0.093 

0.040 0.060 0.063 !0.034 0.106 

0.021 0.040 0.044 0.013 0.086 

0.025 0.052 0.048 0.050 0.100 

0.027 0.047 0.051 0.017 0.090 

0.022 0.042 0.046 0.015 0.098 

0.032 0.058 0.065 0.021 0.100 

0.034 0.051 0.051 0.017 0.093 

0.024 0.037 0.041 0.014 0.108 

0.036 0.052 0.052 0.026 0.091 

0.041 0.061 0.064 0.022 0.109 

299 300 301 302 303 

0.013 0.020 0.022 0.010 0.029 

0.008 0.019 0.021 0.004 0.027 

0.017 0.028 0.030 0.012 0.032 

299 300 301 302 303 

0.092 0.083 0.087 0.047 0.108 

0.098 0.102 0.113 0.056 0.141 

0.070 0.058 0.065 0.039 0.066 

0.088 0.090 0.094 0.046 0.120 

0.088 0.088 0.087 0.047 0.141 

0.065 0.059 0.065 0.034 0.080 

0.089 0.080 0.076 0.046 0.108 

0.085 0.078 0.087 0.044 0.112 

- - - - 0.067 

0.069 0.055 0.054 <0.033 0.055 

0.090 0.084 0.086 0.047 0.086 

0.133 0.117 0.112 0.063 0.167 

0.064 0.062 0.063 0.032 0.076 

0.072 0.064 0.066 0.036 0.079 

0.093 0.096 0.101 0.055 0.155 

0.100 0.080 0.090 0.070 0.110 

299 300 301 302 3

0.028 0.044 0.041 0.020 0.

0.024 0.020 0.034 0.024 0.

0.024 0.029 0.032 0.019 0.

0.032 0.040 0.043 0.023 0.

nd 0.035 0.038 0.022 0.

0.031 0.036 0.037 0.023 0.

0.019 0.032 0.029 0.019 0.

- - - - 0.

0.021 0.024 0.024 0.013 0.

0.019 0.030 0.030 0.017 0.

0.056 0.051 0.047 0.020 0.

0.024 0.024 0.024 0.014 0.

0.036 0.041 0.046 0.023 0.

N 8 8 8 8 8 21 21 21 20 21 3 3 3 3 3 15 15 15 14 16 11 12 12 12 

Min 0.167 0.208 0.218 0.083 0.141 0.021 0.037 0.041 0.011 0.086 0.008 0.019 0.021 0.004 0.027 0.064 0.055 0.054 0.032 0.055 0.019 0.020 0.024 0.013 0.

Median 0.204 0.253 0.286 0.096 0.190 0.031 0.052 0.052 0.019 0.104 0.013 0.020 0.022 0.010 0.029 0.088 0.080 0.087 0.047 0.108 0.024 0.033 0.036 0.020 0.

Max 0.221 0.288 0.352 0.110 0.229 0.043 0.068 0.069 0.050 0.131 0.017 0.028 0.030 0.012 0.032 0.133 0.117 0.113 0.070 0.167 0.056 0.051 0.047 0.024 0.

SD 0.029 0.038 0.044 0.011 0.028 0.007 0.009 0.011 0.004 0.011 0.016 0.019 0.020 0.009 0.035 0.007 0.009 0.009 0.003 0.

CV 14 15 15 11 15 24 17 21 24 10 18 24 23 20 32 28 28 25 17 

Npast 12 11 11 11 11 27 23 23 23 23 6 4 0 7 5 16 15 15 17 17 14 13 13 14 

Medianpast 0.209 0.243 0.251 0.091 0.192 0.032 0.050 0.055 0.019 0.105 0.017 0.021 0.010 0.032 0.084 0.076 0.078 0.044 0.136 0.024 0.030 0.030 0.019 0.

SDpast 0.038 0.047 0.061 0.015 0.042 0.008 0.006 0.009 0.003 0.022 0.006 0.002 0.017 0.014 0.015 0.012 0.014 0.053 0.007 0.006 0.008 0.003 0.

NIST 0.035 0.066 0.069 0.020 0.116 0.024 0.032 0.034 0.015 0.056 0.083 0.091 0.096 0.048 0.120 0.037 0.044 0.041 0.023 0.

NAV 0.217 0.266 0.293 0.096 0.197 0.031 0.052 0.052 0.019 0.104 0.088 0.082 0.087 0.047 0.108 0.024 0.032 0.034 0.020 0.

NAU 0.039 0.048 0.053 0.017 0.036 0.008 0.013 0.013 0.005 0.023 0.017 0.016 0.018 0.010 0.039 0.007 0.011 0.010 0.006 0.

All Lab Report 
 

 

Round Robin LV Laboratory Results
 

All values in μg/mL
 

Total Cryptoxanthin Coenzyme Q10 Phylloquinone (K1) x1000 

Lab 299 300 301 302 303 

C5

FSV-BA
 

FSV-BB
 0.044 0.068 0.073 0.028 0.133 

FSV-BD 

FSV-BE 

FSV-BF 

FSV-BG 

FSV-BH 

FSV-BI 

FSV-BJ 

FSV-BK 

FSV-BL 

FSV-BM 

FSV-BN 

FSV-BO 

FSV-BP 

FSV-BQ 

FSV-BR 

FSV-BS 

FSV-BU 

FSV-BV 

FSV-BW 

FSV-BX 

FSV-CB 

FSV-CC 

FSV-CD 

FSV-CE 

FSV-CF 

FSV-CG 0.0509 0.0758 0.0818 0.0268 0.14 

FSV-CI 

FSV-CS 

FSV-CT 

FSV-CW 

FSV-CZ 

FSV-DA 0.058 0.088 0.094 0.033 0.141 

FSV-DF 

FSV-DI 

FSV-DW 

FSV-ET 

299 300 301 302 303 

0.911 0.697 0.727 0.426 1.076 

0.950 0.710 0.790 0.500 1.190 

0.900 0.600 0.600 0.500 1.100 

1.270 0.790 0.890 0.570 1.020 

1.020 0.694 0.790 0.480 1.110 

299 300 301 302 303 

0.97 0.34 0.29 0.20 0.78 

0.70 0.22 0.21 0.11 0.54 

N 3 3 3 3 3 5 5 5 5 5 2 2 2 2 2 

Min 0.04 0.07 0.07 0.03 0.13 0.900 0.600 0.600 0.426 1.020 0.70 0.22 0.21 0.11 0.54 

Median 0.05 0.08 0.08 0.03 0.14 0.950 0.697 0.790 0.500 1.100 0.84 0.28 0.25 0.16 0.66 

Max 0.06 0.09 0.09 0.03 0.14 1.270 0.790 0.890 0.570 1.190 0.97 0.34 0.29 0.20 0.78 

SD 0.081 0.035 0.047 0.025 0.055 

CV 9 5 6 5 5 

Npast 0 0 0 0 0 0 4 4 7 0 0 0 0 0 0 

Medianpast 0.780 0.830 0.455 

SDpast 

NIST
 

NAV
 0.051 0.076 0.082 0.028 0.139 0.950 0.697 0.790 0.500 1.100
 

NAU
 0.081 0.035 0.047 0.025 0.055 

All Lab Report 
 

 

 

 

 

 

Round Robin LV Laboratory Results
 

All values in μg/mL
 

Analytes Reported By One Laboratory 

Analyte Code 299 300 301 302 303 

Retinyl stearate FSV-DA 0.031 0.035 0.045 0.005 0.008 

trans-Lutein FSV-BB 0.068 

Ubiquinol FSV-BW 0.720 0.490 0.580 0.420 0.860 

Ubiquinone FSV-BW 0.230 0.220 0.210 0.080 0.330 

25-hydroxyvitamin D FSV-CF <0.007 <0.007 0.0070 0.0090 0.0210 

Phytofluene FSV-DA 0.070 0.107 0.120 0.035 0.029 

Phytoene FSV-DA 0.060 0.125 0.134 0.027 0.031 

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 Adjusted median absolute deviation from the median of the non-NIST results

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) 

NIST Mean of NIST results

NAV NIST Assigned Value

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

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

NAU NIST Assigned Uncertainty: √(S2

 + Sbtw 2)

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

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

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

- Not analyzed

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

Legend 

Definition

All Lab Report 

C6

Page 5 / 6 
 

 

 

 

 

 

 

Lab 

FSV-BA 

FSV-BB 

FSV-BD 

FSV-BE 

FSV-BF 

FSV-BG 

FSV-BH 

FSV-BI 

FSV-BJ 

FSV-BK 

FSV-BL 

FSV-BM 

FSV-BN 

FSV-BO 

FSV-BP 

FSV-BQ 

FSV-BR 

FSV-BS 

FSV-BU 

FSV-BV 

FSV-BW 

FSV-BX 

FSV-CB 

FSV-CC 

FSV-CD 

FSV-CE 

FSV-CF 

FSV-CG 

FSV-CI 

FSV-CS 

Round Robin LV Laboratory Results 

Comparability Summary 

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

1 1 1 1 1 1 2 1 1 1
 

1 2 1 1 1 1 1 1 2 1 1
 

1 2
 

1 1 1 1 1
 

1 1 1 2 3 1 1
 

1 1 1 2 1 1 1 1
 

2 1 1 1 1 1 2 1 1 1
 

1 2 1 1 1 1 1 2 1 1
 

1 1 1 1 1 1 1 1 1 1
 

2 2
 

2 1 1
 

1 1
 

1 1 1 1 1 1 1 1 2
 

1 1 2 1 1 1 1 1
 

1 1 1 1 1 1 2 2 2
 

3 1 1
 

1 1 2 3 3
 

4 2 2 1 2 1 1 1 1
 

1 1 1 1 1 1 1
 

1 1 1 1 1 1 1
 

1 1 1 1 1 2 3 2
 

1 1 1 1 1 1 1
 

2 1 1 1 1 1 1
 

1 1 1
 

1 1 1 1 2 1 1 1 2 1
 

2 3 4 1
 

2 1
 

1 2 1 1 1 1 1 1
 

1 1 1 2 2 2
 

1 1 1 1 1 1 1 1 1 1 1
 

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) summarizes your measurement 

performance for a given analyte relative to the consensus 

medians in this study. CS is the average distance (in units of 

standard deviation) of your measurement performance 

characteristics from the consensus performance. CS is 

calculated when the number of quantitative values you reported, 

Nyou, is at least two and at least six participants reported 

quantitative values for the analyte. 

We define CS as follows: 

MINIMUM 4,INTEGER 1
 

you Youi Median i
 

NAU i
 





 FSV-CT 2 1 1 2 1 2
 

C = Concordance = 

CS = + 2
 2 C + AP 



 FSV-CW 3 2 1 2 2 1 1
 

∑ 

= 

N
 

i 1
 

FSV-CZ 1 2 4
 

FSV-DA 1 1 1 1 1 1 1 1 2
 N FSV-DF 1 1
 you 

N 2 FSV-DI 1 1 1 1 1 2 1 2
 you

∑ 

= 

















i
 

i 1
 

NISTa
 1 1 1 1 2 1 1 1 1 2 1
 NAU = NIST Assigned Uncertainty
 

n 38 36 22 30 12 23 22 22 16 13 23
 For further details, please see
 

Duewer DL, Kline MC, Sharpless KE, Brown Thomas J, Gary
 

TR aT g/bT bC tbC aC TLy TbX TLu TZ L&Z KT. Micronutrients Measurement Quality Assurance 

% 1
 Program: Helping participants use interlaboratory comparison 

exercise results to improve their long-term measurement 

74 75 95 70 67 87 86 86 56 69 74
 

% 2
 18 22 5 20 33 9 9 9 44 23 22
 performance. Anal Chem 1999;71(9):1870-8.
 % 3
 5 3 0 3 0 4 5 5 0 8 4
 

% 4
 3 0 0 7 0 0 0 0 0 0 0 

Youi
 

N
 

−Median
 

NAU i
 

1
 

FSV-DW 2 2 3 3
 AP = Apparent Precision = FSV-ET 1 1 1 1 you −

All Lab Report 

C7

Page 6 / 6
 
 

Appendix D. Representative “Individualized Report” for RR55 

Each participant in RR55 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 RR55: 

• 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 12 pages are the “Individualized Report” for the analytes evaluated by 

participant FSV-BA. 

D1
 

 Set 1 of 42 

Individualized Round Robin LV Report: FSV-BA 

Summary 

Serum 299 Serum 300 Serum 301 Serum 302 

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

Total Retinol 0.505 0.481 33 0.626 0.600 32 0.662 0.632 33 0.343 0.329 32 

Retinyl Palmitate 0.10 0.08 11 0.1 0.1 12 0.1 0.1 12 0.02 0.02 10 

α-Tocopherol 16.44 16.58 35 9.70 9.70 34 10.34 10.33 35 2.90 2.84 34 

γ/β-Tocopherol 1.639 1.565 21 1.818 1.700 21 1.925 1.794 21 0.784 0.716 20 

Total β-Carotene 0.435 0.431 25 0.121 0.112 25 0.129 0.124 25 0.051 0.050 24 

trans-β-Carotene 0.408 0.395 11 0.115 0.108 11 0.124 0.115 11 0.051 0.049 11 

Total cis-β-Carotene 0.028 0.031 7 0.006 0.006 5 0.005 0.006 5 0.002 0.003 5 

Total α-Carotene 0.088 0.091 22 0.069 0.071 22 0.073 0.078 22 0.005 0.005 12 

trans-Lycopene 0.217 0.217 8 0.269 0.266 8 0.293 0.293 8 0.101 0.096 8 

Total β-Cryptoxanthin 0.040 0.031 21 0.063 0.052 21 0.068 0.052 21 0.023 0.019 20 

Total Lutein&Zeaxanthin 0.109 0.107 21 0.103 0.110 22 0.111 0.116 22 0.063 0.063 20 

D2

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 

100 Bureau Drive Stop 8392 

Gaithersburg, MD 20899-8392 USA Email

Individualized Report 
 

 Set 1 of 42

Individualized RR LV Report: FSV-BA 

Total Retinol 

Apparent Precision, SD 

[Analyte], μg/mL 

249256264284299290300292301288293302287303

Your [Analyte], μg/mL

Median [Analyte], μg/mL 

Long-term Precision, SD 

Apparent Precision, SD 

Concordance, 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%) 

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 

#299 Lyophilized: #249(44), #256(46), #264(48), #284(52) Augmented, multi-source (SRM 968c Level II) 

#300 Lyophilized: #290(RR53) Native, single-source 

#301 Fresh-frozen: #292(RR53) Same material as #300 

#302 Fresh-frozen: #293(RR53) Native, single-source 

#303 Fresh-frozen: #287(RR52) Native, single-source, hemolyzed 

 Individualized Report Page 2 / 12 

D3
 

 Set 1 of 42

Individualized RR LV Report: FSV-BA 

Retinyl Palmitate 

Apparent Precision, SD 

[Analyte], μg/mL 

249256264284299290300292301288293302287303 

Your [Analyte], μg/mL

Median [Analyte], μg/mL 

Long-term Precision, SD 

Apparent Precision, SD 

Concordance, 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%) 

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 

#299 Lyophilized: #249(44), #256(46), #264(48), #284(52) Augmented, multi-source (SRM 968c Level II) 

#300 Lyophilized: #290(RR53) Native, single-source 

#301 Fresh-frozen: #292(RR53) Same material as #300 

#302 Fresh-frozen: #293(RR53) Native, single-source 

#303 Fresh-frozen: #287(RR52) Native, single-source, hemolyzed 

 Individualized Report Page 3 / 12 

D4
 

 Set 1 of 42

Individualized RR LV Report: FSV-BA 

α-Tocopherol 

Apparent Precision, SD 

[Analyte], μg/mL 

249256264284299290300292301288293302287303 

Your [Analyte], μg/mL

Median [Analyte], μg/mL 

Long-term Precision, SD 

Apparent Precision, SD 

Concordance, 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%) 

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 

#299 Lyophilized: #249(44), #256(46), #264(48), #284(52) Augmented, multi-source (SRM 968c Level II) 

#300 Lyophilized: #290(RR53) Native, single-source 

#301 Fresh-frozen: #292(RR53) Same material as #300 

#302 Fresh-frozen: #293(RR53) Native, single-source 

#303 Fresh-frozen: #287(RR52) Native, single-source, hemolyzed 

 Individualized Report Page 4 / 12 

D5
 

 Set 1 of 42

Individualized RR LV Report: FSV-BA 

γ/β-Tocopherol 

Apparent Precision, SD 

[Analyte], μg/mL 

249256264284299290300292301288293302287303

Your [Analyte], μg/mL

Median [Analyte], μg/mL 

Long-term Precision, SD 

Apparent Precision, SD 

Concordance, 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%) 

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 

#299 Lyophilized: #249(44), #256(46), #264(48), #284(52) Augmented, multi-source (SRM 968c Level II) 

#300 Lyophilized: #290(RR53) Native, single-source 

#301 Fresh-frozen: #292(RR53) Same material as #300 

#302 Fresh-frozen: #293(RR53) Native, single-source 

#303 Fresh-frozen: #287(RR52) Native, single-source, hemolyzed 

 Individualized Report Page 5 / 12 

D6
 

 Set 1 of 42

Individualized RR LV Report: FSV-BA 

Total β-Carotene 

Apparent Precision, SD 

[Analyte], μg/mL 

249256264284299290300292301288293302287303 

Your [Analyte], μg/mL

Median [Analyte], μg/mL 

Long-term Precision, SD 

Apparent Precision, SD 

Concordance, 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%) 

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 

#299 Lyophilized: #249(44), #256(46), #264(48), #284(52) Augmented, multi-source (SRM 968c Level II) 

#300 Lyophilized: #290(RR53) Native, single-source 

#301 Fresh-frozen: #292(RR53) Same material as #300 

#302 Fresh-frozen: #293(RR53) Native, single-source 

#303 Fresh-frozen: #287(RR52) Native, single-source, hemolyzed 

 Individualized Report Page 6 / 12 

D7
 

 Set 1 of 42

Individualized RR LV Report: FSV-BA 

trans-β-Carotene 

Apparent Precision, SD 

[Analyte], μg/mL 

249256264284299290300292301288293302287303 

Your [Analyte], μg/mL

Median [Analyte], μg/mL 

Long-term Precision, SD 

Apparent Precision, SD 

Concordance, 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%) 

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 

#299 Lyophilized: #249(44), #256(46), #264(48), #284(52) Augmented, multi-source (SRM 968c Level II) 

#300 Lyophilized: #290(RR53) Native, single-source 

#301 Fresh-frozen: #292(RR53) Same material as #300 

#302 Fresh-frozen: #293(RR53) Native, single-source 

#303 Fresh-frozen: #287(RR52) Native, single-source, hemolyzed 

 Individualized Report Page 7 / 12 

D8
 

 Set 1 of 42

Individualized RR LV Report: FSV-BA 

Total α-Carotene 

Apparent Precision, SD 

[Analyte], μg/mL 

249256264284299290300292301288293302287303 

Your [Analyte], μg/mL

Median [Analyte], μg/mL 

Long-term Precision, SD 

Apparent Precision, SD 

Concordance, 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%) 

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 

#299 Lyophilized: #249(44), #256(46), #264(48), #284(52) Augmented, multi-source (SRM 968c Level II) 

#300 Lyophilized: #290(RR53) Native, single-source 

#301 Fresh-frozen: #292(RR53) Same material as #300 

#302 Fresh-frozen: #293(RR53) Native, single-source 

#303 Fresh-frozen: #287(RR52) Native, single-source, hemolyzed 

 Individualized Report Page 8 / 12 

D9
 

 Set 1 of 42

Individualized RR LV Report: FSV-BA 

trans-Lycopene 

Apparent Precision, SD 

[Analyte], μg/mL 

249256264284299290300292301288293302287303

Your [Analyte], μg/mL

Median [Analyte], μg/mL 

Long-term Precision, SD 

Apparent Precision, SD 

Concordance, 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%) 

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 

#299 Lyophilized: #249(44), #256(46), #264(48), #284(52) Augmented, multi-source (SRM 968c Level II) 

#300 Lyophilized: #290(RR53) Native, single-source 

#301 Fresh-frozen: #292(RR53) Same material as #300 

#302 Fresh-frozen: #293(RR53) Native, single-source 

#303 Fresh-frozen: #287(RR52) Native, single-source, hemolyzed 

 Individualized Report Page 9 / 12 

D10
 

 Set 1 of 42

Individualized RR LV Report: FSV-BA 

Total β-Cryptoxanthin 

Apparent Precision, SD 

[Analyte], μg/mL 

249256264284299290300292301288293302287303

Your [Analyte], μg/mL

Median [Analyte], μg/mL 

Long-term Precision, SD 

Apparent Precision, SD 

Concordance, 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%) 

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 

#299 Lyophilized: #249(44), #256(46), #264(48), #284(52) Augmented, multi-source (SRM 968c Level II) 

#300 Lyophilized: #290(RR53) Native, single-source 

#301 Fresh-frozen: #292(RR53) Same material as #300 

#302 Fresh-frozen: #293(RR53) Native, single-source 

#303 Fresh-frozen: #287(RR52) Native, single-source, hemolyzed 

 Individualized Report Page 10 / 12 

D11
 

 Set 1 of 42

Individualized RR LV Report: FSV-BA 

Total Lutein&Zeaxanthin 

Apparent Precision, SD 

[Analyte], μg/mL 

249256264284299290300292301288293302287303

Your [Analyte], μg/mL

Median [Analyte], μg/mL 

Long-term Precision, SD 

Apparent Precision, SD 

Concordance, 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%) 

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 

#299 Lyophilized: #249(44), #256(46), #264(48), #284(52) Augmented, multi-source (SRM 968c Level II) 

#300 Lyophilized: #290(RR53) Native, single-source 

#301 Fresh-frozen: #292(RR53) Same material as #300 

#302 Fresh-frozen: #293(RR53) Native, single-source 

#303 Fresh-frozen: #287(RR52) Native, single-source, hemolyzed 

 Individualized Report Page 11 / 12 

D12
Set 1 of 42 

Individualized Round Robin LV Report: FSV-BA
 

Graphical Comparability Summary
 

Total Retinol α-Tocopherol Total β-Carotene 

D13

Retinyl Palmitate γ/β-Tocopherol trans-β-Carotene To

Total Lycopene δ-Tocopherol Total cis-β-Carotene Total L

trans-Lycopene Total β-Cryptoxanthin Total α-Carotene C

Individualized Report 
 

 

Appendix E. Shipping Package Inserts for RR20 

The following five items were included in each package shipped to an RR20 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
Nov 17, 2003 

Dear Colleague: 

UNITED STATES DEPARTMENT OF COMMERCE 

National Institute of Standards and Technology 

Gaithersburg, Maryland 20899-0001 

The samples within this package constitute Vitamin C Round Robin 20 (RR20) of the 2004 Micronutrients 

Measurement Quality Assurance Program. 

RR20 consists of four vials of frozen serum test samples (#35, #52, #68j and #69), one vial of ascorbic acid 

solid control material (Control), and two vials of frozen serum control materials (Control #1 and Control #2). 

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 10-fold more accurate than routine 0.5 

mL volumetric measurements.) 

The two serum control materials are a new component of the M2

QAP for Vitamin C. Please use these 

materials to validate the performance of your measurement system before you analyze the test samples. The 

target value for Control #1 is 8.5 ±0.5 μmol/L sample; the target value for Control #2 is 28.1 ±1.0 μmol/L 

sample. 

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. 

The report for RR19 will be mailed during the week of Nov 17, 2003. If you find your results for RR19 

unsatisfactory, we.recommend that you obtain Standard Reference Material (SRM) 970 Ascorbic Acid in 

Serum to validate your methodology and value assign in-house control materials. Thi_s SRM may be 

purchased from the Standard Materials Reference Program at NIST (Tel: 301-975-6776, Fax: 301-948-37?0, 

or e-mail: srminfo@nist.gov). 

We are pl~ased to announce that due to the generous funding support from the Centers for Disease Control in 

Atlanta, a second Vitamin C Round Robin (RR21) will be distributed, at no cost to you, during the week of 

May 3, 2004. As before, we will send you a reminder via e-mail or fax about a week prior to shipment. 

If you have any questions or concerns about the Vitamin C M icronutrients Measurement Quality Assurance 

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

e-mai I: jbthomas@nist.gov. 

We ask that you return your results for these RR20 samples before March 5, 2004. We would appreciate 

receiving your results as soon as they become available. Please use the attached form. Your results will be 

kept confidential. 

e nice Brown Thomas 

search Chemist 

Analytical Chemistry Division 

Chemical Science and Technology Laboratory 

Enclosures: Protocols, Preparation and Analysis of Control Materials and Analysis of Test Samples 

RR20 Report Form for Ascorbic Acid Solid Control Material Preparation N IS I 

RR20 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 = 28.4 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 ) + (g Diluent 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 calibrate 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 

materials (see protocol below). The target values for these materials are: 

Control #1: 8.5 ±0.5 μmol/L of sample 

Control #2: 28.1 ±1.0 μmol/L of sample. 

If your measured values are not close to these target values, 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: 301-975-3120 or Jeanice.BrownThomas@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 materials 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 materials 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 20 

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 before March 5, 2004 to: 

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 20 

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 Serum Control #1 

Target: 8.5 ±0.5 μmol/L 

μmol/L of Sample Serum Control #2 

Target: 28.1 ±1.0 μmol/L 

Serum Test Sample #35 μmol/L of Sample 

Serum Test Sample #52 μmol/L of Sample 

Serum Test Sample #68 μmol/L of Sample 

Serum Test Sample #69 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 before March 5, 2004 to: 

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 20
 

NIST Micronutrients Measurement Quality Assurance Program
 

Packing List and Shipment Receipt Confirmation Form
 

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

Sample Form 

VitC #35 Liquid frozen (1:1 serum:10% MPA) 

VitC #52 Liquid frozen (1:1 serum:10% MPA) 

VitC #68 Liquid frozen (1:1 serum:10% MPA) 

VitC #69 Liquid frozen (1:1 serum:10% MPA) 

Control #1 Liquid frozen (1:1 serum:10% MPA) 

Control #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 RR20 

The following three 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
May 5, 2004 

Dear Colleague: 

UNITED STATES DEPARTMENT OF COMMERCE 

National Institute of S~ndarda and Technology 

Gaithersburg, Maryland 20899-0001 

Enclosed is the summary report of the results for Round Robin 20 (RR20) 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 a summary of individual laboratory 

performance and interlaboratory accuracy and repeatability. As in previous reports, the estimated 

standard deviations (eSD) for the measurements are defined as 0.74x interquartile range and the 

estimate coefficients of variation ( eCV) are defined as 1 OOx esp/median. 

RR 20 consisted of four test samples (#35, #52, #68, and #69), two serum control materials, and 

one solid control material for preparation of T AA control solutions. Details regarding the 

samples can be found in the enclosed report. 

If you have concerns regarding your laboratory's perfonnance, 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-

948-3730. 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 study (RR 21) for the 2004 Vitamin C in Serum QA 

Program will be shipped (during the week of May 17). If you have questions or concerns regarding 

this report, please contact me at 301-975-3120; e-mail: jbthomas@nist.gov; or fax: 301-977-

0685. 

sm ~ · ce Brown Thomas 

earch Chemist 

Analytical Chemistry Division 

Chemical Science and Technology Laboratory 

Enclosures 

F2
 

The NIST M2QAP Vitamin C Round Robin 20 (RR20) 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 two serum control samples, and the four serum test 

samples. 

2 Graphical summary of your RR 20 sample measurements. 

Page “All Lab” Report 

1 A tabulation of results and summary statistics for Total Ascorbic Acid [TAA] in the RR20 

samples and control/calibration solutions. 

Serum-based Samples. Two serum controls and four unknowns were distributed in RR20. 

CS1 SRM 970 level 1, ampouled in mid-1998. 

CS2 SRM 970 level 2, ampouled in mid-1998. 

S20:1 Serum 35, ampouled in late 2001, previously distributed as sample S12:2 (RR17, Sep-02) 

and S18:1 (RR18, Mar-03). An augmented serum. 

S20:2 Serum 52, ampouled in late 2001, previously distributed as sample 16:3 (RR13, Mar-02) and 

S17:3 (RR17, Sep-02). An augmented serum. 

S20:3 Serum 69, SRM 970 level 1, ampouled in mid-1998. This material was distributed with 

identification in RR11 (Oct-98) and RR12 (Mar-99) and as samples S13-1 (RR13, Mar-00), 

S14-3 (RR14, Mar-01), S15:1 (RR15, Sep-01), and 16:1 (RR16, Mar-02). An augmented 

serum. 

S20:4 Serum 69, SRM 970 level 2, ampouled in mid-1998. This material was distributed with 

identification in RR11 (Oct-98) and RR12 (Mar-99) and as samples S13-2 (RR13, Mar-00), 

S14-4 (RR14, Mar-01), S15:2 (RR15, Sep-01), and 18:3 (RR18, Mar-03). An augmented 

serum. 

Results. 

1)	 All participants who prepared the four control/calibration solutions (the three “Dilute Solutions” and 

the 5% MPA “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 (≈0.55 OD), the calculated E1% #1”(≈550 dL/g·cm). 

2)	 Judging from the calibration parameters calculated for the control/calibration solutions (intercepts 

close to 0.0 and slopes close to 1.0), the measurement systems for most participants are well 

calibrated. 

3)	 Everyone reported consistent results for the SRM 970 levels used as controls (CS1 and CS2) and as 

test samples (S20:3 and S20:4). This implies that all measurements systems are in statistical control. 

However, not all participants appear to have believed the results for the controls. Several 

participants reported values for the controls (and consequently for the corresponding test samples) 

that were well outside the target range. If the measured values for the control samples are not close 

to the targets, even if your measured and calculated values for the calibration solutions agree, there is 

problem with your measurement system. 

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4)	 Over the past five years, we have been monitoring the stability of [TAA] in both levels of SRM 970 

through interlaboratory studies and NIST analyses. Based on the interlaboratory data and data from 

NIST, the assigned concentration levels of [TAA] have decreased (by about 10 – 20 %) in both levels 

of the SRM since certification in 1998, but have stabilized over time. We will be recertifying the 

material in the next few months and will issue a revised Certificate of Analysis for the SRM. 

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Appendix G. “All-Lab Report” for RR20 

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. The only attributed results are those 

reported by NIST. The NIST results are not used in the assessment of the consensus 

summary results of the study. 

G1
Micronutrients Measurement Quality Assurance Program for Total Ascorbic Acid 

"Round Robin" 20 - March 2004 

Control / Calibration Samples MPA Dilute Solution 1 

G2

Density 

Lab Date Dil:1 Dil:2 Dil:3 Dil:1 Dil:2 Dil:3 MPA Inter Slope R2 SEE g/mL λmax Amax E1% CS#1 CS#2 S20:1 S20:2 

VC-MA 23/02/04 55.9 28.3 14.0 59.0 28.7 14.3 0.0 -0.39 1.05 1.000 0.6 1.030 243. 0.5524 560.7 7.9 26.0 24.6 50

VC-MB 01/03/04 51.6 28.6 14.3 46.2 24.0 13.7 3.6 2.39 0.82 0.993 1.9 1.033 244. 0.4769 524.4 10.3 29.7 23.8 49

VC-MC 19/02/04 57.2 28.6 14.3 59.1 30.1 16.9 0.0 0.96 1.02 0.998 1.2 1.031 243. 0.5829 578.8 6.9 28.3 20.7 43

VC-ME 04/03/04 58.4 28.8 14.2 52.9 26.0 12.5 0.4 0.12 0.90 1.000 0.4 1.027 244. 0.5906 574.0 5.5 20.7 16.9 34

VC-MG 02/03/04 59.7 30.6 16.2 61.0 30.4 14.5 0.0 -0.96 1.03 0.999 1.1 1.029 243.7 0.5640 536.1 20.7 44.2 34.6 65

VC-MH 12/12/03 59.7 29.8 14.5 59.9 29.9 14.6 0.0 0.02 1.00 1.000 0.0 1.031 243.7 0.5931 564.0 8.2 28.6 22.5 54

VC-MI 01/03/04 58.6 29.5 13.8 59.5 29.3 13.3 0.0 -0.43 1.02 1.000 0.5 1.032 7.9 31.1 24.3 52

VC-MK 03/03/04 61.8 30.3 15.3 60.5 29.6 15.7 0.3 0.44 0.97 1.000 0.4 1.033 244. 0.6023 553.1 17.8 36.7 26.0 53

VC-MR 25/11/03 58.4 29.2 14.4 57.0 28.8 14.1 0.0 0.09 0.98 1.000 0.2 1.029 244. 0.5860 569.3 7.9 27.5 22.3 47

VC-MT 08/03/04 24.1 12.3 5.7 25.3 12.6 5.2 0.0 -0.38 1.06 0.999 0.4 1.033 243. 0.2330 548.0 6.4 25.1 19.7 44

VC-MY 15/03/04 5.1 19.8 13.1 27

NIST 24/10/03 59.1 29.2 14.0 58.7 32.1 13.6 0.0 0.47 1.00 0.996 2.0 1.024 243. 0.5723 549.7 8.9 28.8 22.5 44

10 10 10 10 10 10 10 10 9 9 9 11 11 11 1

54.6 27.6 13.7 54.0 26.9 13.5 0.4 1.031 243.6 0.5312 556.5 9.5 28.9 22.6 47

11.0 5.4 2.9 11.1 5.4 3.2 1.1 0.002 0.5 0.1181 17.9 5.1 6.9 5.5 10

24.1 12.31 5.7 25.3 12.60 5.2 0.0 1.027 243.0 0.2330 524.4 5.1 19.8 13.1 27

56.2 28.57 14.0 53.9 26.71 13.4 0.0 1.029 243.0 0.5524 548.0 6.6 25.6 20.2 43

58.4 28.98 14.3 59.1 29.04 14.2 0.0 1.031 243.7 0.5829 560.7 7.9 28.3 22.5 49

59.4 29.73 14.5 59.8 29.84 14.6 0.2 1.032 244.0 0.5906 569.3 9.2 30.4 24.4 52

61.8 30.61 16.2 61.0 30.41 16.9 3.6 1.033 244.0 0.6023 578.8 20.7 44.2 34.6 65

1.9 0.9 0.4 2.5 1.5 1.1 0.0 0.003 0.4 0.0280 18.8 2.3 4.1 3.0 6

3 3 3 4 5 7 0.26 0.18 5 3 29 15 14 1

Gravimetric, μmol/L Measured, μmol/L Calibration Parameters Spectrophotometry Measured, μm

N N 

Average Average 

SD SD 

Min Min 

%25 %25 

MADe eSD 

CV CV 

Median Median 

%75 %75 

Max Max 

All Lab Report 
Appendix H. Representative “Individualized Report” for RR20 

Each participant in RR20 received an “Individualized Report” reflecting their reported 

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

“VC-MA”. 

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Set 1 of 12 

Vitamin C "Round Robin" 20 Report: Participant VC-MA
 

Date RR Method 

09/18/01 15 HPLC-EC 

11/18/02 16 HPLC-EC 

12/12/02 17 HPLC-EC 

03/20/03 18 HPLC-EC 

11/13/03 19 HPLC-EC 

02/23/04 20 HPLC-EC 

Date RR Sample 

12/12/02 17 S17:2 

03/20/03 18 S18:1 

02/23/04 20 S20:1 

11/18/02 16 S16:3 

12/12/02 17 S17:3 

02/23/04 20 S20:2 

09/23/98 11 S11:1 

04/02/99 12 S12:1 

09/17/01 13 S13:1 

09/27/01 14 S14:3 

09/18/01 15 S15:1 

11/18/02 16 S16:1 

11/13/03 19 S19:4 

02/23/04 20 S20:3 

09/23/98 11 S11:2 

04/02/99 12 S12:2 

09/17/01 13 S13:2 

09/27/01 14 S14:4 

09/18/01 15 S15:2 

03/20/03 18 S18:3 

02/23/04 20 S20:4 

49.2 

47.7 

27.6 

25.7 

25.4 

28.8 

25.9 

51.4 

47.0 

27.7 

26.4 

25.6 

29.2 

25.2 

0.5 

0.5 

1.0 

1.0 

1.0 

1.0 

1.0 

25.2 

23.7 

27.7 

26.0 

25.5 

29.0 

25.5 

0.8 

0.2 

0.1 

0.5 

0.2 

0.3 

0.5 

MPA Dilute Solution 1 Control/Calibration Solutions 

Density Spectrophotometry Ymeas = Inter + Slope* Xgrav 

3 49.0 2.1 1.9 

8 8.2 0.2 0.6 

7 26.1 0.4 1.7 

g/mL 

1.027 

1.032 

1.026 

1.026 

1.026 

1.031 

λmax 

243.0 

242.0 

242.0 

244.0 

243.0 

243.0 

Amax 

0.547 

0.575 

0.552 

0.509 

0.584 

0.552 

E1% 

556.5 

576.5 

551.0 

563.1 

561.9 

560.7 

Inter Slope R2 SEE 

0.0 1.04 1.000 0.05 

-0.4 1.07 0.999 0.90 

-0.3 1.06 1.000 0.49 

-0.1 1.02 1.000 0.18 

1.1 1.03 0.998 1.24 

-0.4 1.05 1.000 0.65 

Mean 1.028 242.8 0.55 561.6 

SD 0.003 0.8 0.03 8.5 

CV 0.25 0.31 4.7 1.5 

[TAA] mmol/Lsample 

Rep1 

23.3 

22.7 

25.1 

Rep2 

23.4 

23.7 

24.1 

Fadj 

1.0 

1.0 

1.0 

Mean 

23.4 

23.2 

24.6 

SDdup 

0.1 

0.7 

0.7 

N Mean SDrepeat SDreprod 

3 23.7 0.6 0.8 

49.9 

49.7 

50.6 

14.7 

15.2 

8.4 

8.0 

8.9 

8.8 

7.8 

8.3 

44.9 

49.1 

50.0 

14.3 

15.6 

8.5 

7.7 

8.7 

8.8 

8.6 

8.1 

1.0 

1.0 

1.0 

0.5 

0.5 

1.0 

1.0 

1.0 

1.0 

1.0 

1.0 

47.4 

49.4 

50.3 

7.2 

7.7 

8.5 

7.8 

8.8 

8.8 

8.2 

8.2 

3.5 

0.4 

0.4 

0.2 

0.1 

0.1 

0.2 

0.1 

0.0 

0.5 

0.1 

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

Micronutrients Measurement Quality Assurance Program 

National Institute of Standards and Technology 

100 Bureau Drive Stop 8392 Fax: (301) 977-0685 

Gaithersburg, MD 20899-8392 USA Email: david.duewer@nist.gov 

Individualized Report Page 1/2 

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Set 1 of 12 

Vitamin C "Round Robin" 20 Report: Participant VC-MA 

Total Ascorbic Acid 

S17:2S18:1S20:1S16:3S17:3S20:2

RR11RR12RR13RR14RR15RR16RR18RR19RR20 

[Total Ascorbic Acid], μmol/L 

Your [Total Ascorbic Acid], μmol/L

Median [Total Ascorbic Acid], μmol/L 

Apparent Precision, SD 

Concordance, SD 

3rd Quartile (75%) You, RR 20 NIST, RR 20 Median (50%) You, RR 15-19 Others, RR 20 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 

S20:1 Serum 35, previously distributed in RRs 17 and 18 

S20:2 Serum 52, previously distributed in RRs 16 and 17 

S20:3 SRM 970 Level 1, previously distributed in RRs 11, 12, 13, 14, 15, 16, and 19 

S20:4 SRM 970 Level 2, previously distributed in RRs 11, 12, 13, 14, 15, and 18 

Individualized Report Page 2/2 

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