NISTIR 7880-20 

NIST Micronutrients Measurement 

Quality Assurance Program 

Summer 2002 

Comparability Studies 

Results for Round Robin LII 

Fat-Soluble Vitamins and Carotenoids in Human Serum 

and Round Robin 17 Ascorbic Acid in Human Serum 

David L. Duewer 

Margaret C. Kline 

Sam A. Margolis (Retired) 

Katherine E. Sharpless 

Jeanice B. Thomas 

 

 

 

 

 

 

 

 

 

NISTIR 7880-20 

NIST Micronutrients Measurement 

Quality Assurance Program 

Summer 2002 

Comparability Studies 

Results for Round Robin LII 

Fat-Soluble Vitamins and Carotenoids in Human Serum 

and Round Robin 17 Ascorbic Acid in Human Serum 

David L. Duewer 

Sam A. Margolis (Retired) 

Katherine E. Sharpless 

Jeanice B. Thomas 

Chemical Sciences Division 

Material Measurement Laboratory 

Margaret C. Kline 

Biomolecular Measurement Division 

Material Measurement Laboratory 

-XQH 2013

 U.S. Department of Commerce 

Cameron F. Kerry, 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 

Summer 2002 MMQAP measurement comparability improvement studies: 1) Round Robin LII FatSoluble Vitamins and Carotenoids in Human Serum and 2) Round Robin 17 Total Ascorbic Acid in 

Human Serum. The materials for both studies were shipped to participants in June 2002; 

participants were requested to provide their measurement results by September 13, 2002. 

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 LII: Fat-Soluble Vitamins and Carotenoids in Human Serum ............................. 1
	

Round Robin 17: Vitamin C in Human Serum............................................................................... 2
	

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

Appendix A. Shipping Package Inserts for RR52........................................................................ A1
	

Appendix B. Final Report for RR52 .............................................................................................. B1 

Appendix C. “All-Lab Report” for RR52 ...................................................................................... C1
	

Appendix D. Representative “Individualized Report” for RR52 ............................................... D1
	

Appendix E. Shipping Package Inserts for RR17 ......................................................................... E1
	

Appendix F. Final Report for RR17............................................................................................... F1
	

Appendix G. “All-Lab Report” for RR17..................................................................................... G1
	

Appendix H. Representative “Individualized Report” for RR17............................................... H1 

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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 LII: Fat-Soluble Vitamins and Carotenoids in Human Serum 

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

LII comparability study (hereafter referred to as RR52) 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 

June 2002. 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 RR52 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 17: Vitamin C in Human Serum 

Participants in the MMQAP Vitamin C in Human Serum Round Robin 17 comparability study 

(hereafter referred to as RR17) received three frozen serum test samples 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 June 

2002. The communication materials included in the sample shipment are provided in Appendix E. 

The test 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 RR17 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. 

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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 RR52 

The following three items were included in each package shipped to an RR52 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
June 10, 2002 

Dear Colleague: 

UNITED STATES DEPARTMENT OF COMMERCE 

National Institute of Standards and Technology 

Gaithersburg, Maryland 20899-0001 

Enclosed is the set of samples for the second quality assurance round robin exercise (Round Robin Lii) 

for the fat-soluble vitamins and carotenoids in serum. You will find one v'ial of each of four liquid-frozen 

and one lyophilized serum samples for analysis along with a form for reportil\g your results. When 

reporting your results, please submit one value for each analyte for a given serum sample. If an obtained 

value is below your limit of quantification, please indicate this result on the form by using NQ (Not 

Quantified). Results are due to NIST by September 13, 2002. 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 mid-September. 

Lyophilized samples should be reconstituted with 1.0 mL ofHPLC-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 retinol 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 sample 289. 

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

32"5 nm (ethanol); retinyl palmitate, 975 at 325 nm (ethanol); ix-tocopherol, 75.8 at 292 nm (ethanol); ytocopherol, 91.4 at 298 nm (ethanol); ix-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 Lil to: 

Micronutrients Measurement Quality Assurance Program 

NIST 

100 Bureau Drive Stop 8392 

Gaithersburg, MD 20899-8392 

Fax: (301) 977-0685 

As you are aware, the intent-to-participate forms for the 2003 QA Program were mailed in May. Please 

return all forms by September 1, 2002. Laboratories will be invoiced for the 2003 program at the end of 

September 2002. Samples for the first fat-soluble vitamins/carotenoids and vitamin C in serum round 

robins will be shipped during the· first week of November 2002. Please call me at (301) 975-3120; e-mail 

me at jbthomas@nist.gov; or mail/fax queries to the above address if you have any questions or 

comments. 

· ce Brown Tho 

Re arch Chemist 

Analytical Chemistry Division 

Chemical Science and Technology Laboratory 

Enclosures N•SI 

A2
 

 

 

Participant #: ________ Date: _____________ 

Round Robin LII 

NIST Micronutrients Measurement Quality Assurance Program 

Analyte 284 285 286 287 288 Units* 

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 

trans-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 {284,285,286,287} frozen when received? Yes | No 

Comments: 

Mail: M2QAP 

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

Gaithersburg, MD 20899-8392 16-Sep-2002 Email: David.Duewer@NIST.gov 

A3
 

 

 

 

Participant #: ________ Date: _____________ 

Fat-Soluble Vitamins Round Robin LII 

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? 

#284 Lyophilized Yes (1 ml H2O) 

#285 Liquid frozen No 

#286 Liquid frozen No 

#287 Liquid frozen No 

#288 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 {285,286,287,288} arrived frozen 

4) Store the samples upright 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 {285,286,287,288} 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 

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Appendix B. Final Report for RR52 

The following four 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
October 15, 2002 

Dear Colleague: 

UNITED STATES DEPARTMENT OF COMMERCE 

National Institute of Standards and Technology 

Gaithersburg, Maryland 20899-0001 

Enclosed is the summary repo'rt of the results for Round Robin Lil (RR 52) for fat-soluble vitamins and 

carotenoids. Included in this report are: a summary of data for all laboratories; the measurement 

comparability summary for evaluating laboratory performance; a summary of individual laboratory 

performance and inter laboratory accuracy and precision; and a summary of the NIST assigned value 

(NAY) vs. your laboratory value for the analytes that you measured. ·As in previous reports, the NISTassigned values are equally weighted means of the medians from this interlaboratory comparison 

exercise and the means from the analyses performed by NIST. 

Data for evaluating laboratory· performance in RR 52 are provided in the comparability summary (Score· 

Card) on page 5 of the "All Lab Report." Laboratory comparability is summarized as follows: results 

rated l to 3 are within I 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. 

Confirmation notices acknowledging the receipt of.your intent-to-participate form for the 2003 QA 

Program have been mailed. All participating laboratories have been invoiced and should have received 

billing information as well. If you plan to participate in the 2003 program and have not received a 

confirm~tion from us, please contact me immediately. 

Samples for the first round robin exercise (RR53) will be distributed during the week of November 4, 

2002. We will send you a reminder via e-mail or fax a week prior to shipment. Please notify us, 

preferably before the first week of November, if you have special shipping instructions. 

If you have af!Y questions 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@tiist.gov; fax: 301/977-0685. 

I\ 

!' l J 

Sincerely, . i ....Y,) 

~ !/ cJ-----1 Lm11 ~ I I 

ice Brown Thomas 

esearch Chemist 

Analytical Chemistry Division 

Chemical Science and Technology Laboratory 

cc: L.C. Sander 

S.A. Wise 

Enclosures 

NlSI 

B2
 

 

 

 

 

 

 

 

 

 

 

The NIST M2QAP Round Robin LI (RR52) report consists of: 

Page
	

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

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

n each analyte you report that is also reported by at least 10 other participants. 

n+1 The “target” plot version of your “Comparability Summary” scores. 

Page “All Lab” Report 

1-3 

4a 

4b 

5 

Samples. 

Serum 

284 

285 

286 

287 

288 

“Individualized” Report
	

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

A list of results for the four analytes reported by only one laboratory. 

A legend for the above two lists.
	

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

The five sera below were distributed in RR52.
	

Description
	

Lyophilized blended serum with native 

carotenoid levels, augmented with α- and δtocopherol; SRM 968c Level II. 

The same fresh-frozen blended serum as #288, 

augmented with ≈0.3 μg/mL trans-retinol 

The same fresh-frozen blended serum as #288, 

augmented with ≈0.3 μg/mL 13-cis-retinol 

Fresh-frozen single-donor hemolyzed serum 

with endogenous augmented carotenoid levels. 

Provided to the M2QAP by the CDC. 

Fresh-frozen blended serum, stored for five 

years at –80 °C. 

Prior Distributions
	

#249 in RR44 (9/98), #256 in RR46 (6/99), 

#264 in RR48 (3/01). 

Initial distribution.
	

Initial distribution.
	

Initial distribution.
	

Initial distribution.
	

Observations 

1)		 Several participants noted that serum #287 was somewhat hemolyzed. With the exception of one 

participant who noted that the hemolysis interfered with their carotenoid measurements, the 

hemolysis had little or no apparent influence on measurements. 

2)		 Sera Stability. There has been no significant change in the median level or in the variability of any 

measurand in serum #284, SRM 968c Level II. 

3)		 Total versus trans-retinol. Sera #285, #286, and #288 were intentionally designed to help sort out 

the “Total/trans”-retinol issues we commented on in the RR51 report. The three sera were prepared 

from the same base material, a serum pool low in retinol and most other measurands. The three sera 

were produced at the same time using as close to the same preparation, handling, and storage 

B3
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

protocols as we could manage. The only intentional difference in the three materials was retinol: 

#285 was augmented from with 0.3 μg/mL trans-retinol and #286 was augmented with the same 

concentration of 13-cis-retinol. The chemical identity and purity of both materials was checked 

chromatographically. The trans-retinol spiking solution was prepared gravimetrically; the 13-cisretinol was prepared spectrophotometrically to match the trans-retinol concentration using the 

extinction coefficients given in Table II of Hubbard R, Brown PK, Bownds D, Methods of 

Enzymology 1971;18c:615-653 (after adjusting to the correct molecular weight, the coefficients in 

ethanol are, respectively, 1843 dL/g·cm and 1688 dL/g·cm) . The base serum and spiking level were 

chosen to provide a not-unreasonably-high “total” level in the two spiked samples while providing 

similar 13-cis- and trans-retinol levels in serum #286. 

Results 

a)		 After discussion of their original reported values, several participants re-evaluated their 

“retinol” identification and/or measurement protocol and decided that they were reporting the 

wrong component. 

b)		 The “trans-retinol” for the three sera is about what we expect, although there are only seven 

complete sets (including two NIST sets) so the “robust” medians are not very robust: 0.33 

μg/mL in the base serum pool #288, 0.38 μg/mL in the 13-cis-augmented #286, and 0.61 

μg/mL in the trans-augmented #285. 

c)		 The “total retinol” for the three sera is (mostly) also about what we expect: 0.33 μg/mL in the 

base serum pool #288, 0.58 μg/mL in the 13-cis-augmented #286, and 0.64 μg/mL in the transaugmented #285. However, five of the 38 values for the 13-cis-augmented #286 are halfway 

between (about 0.45 μg/mL) what we expect for total and trans-retinol. Given the normal 

among-participant variation in the reported values, the most quantitative way of evaluating 

these data is by examining the 

differences between the two 

Relative Frequency

trans­

(Sera #285-#288) 

13-cis­

(Sera #286-#288) 

? 

0.05 0.15 0.25 0.35 0.45
 

augmented sera (#285 and #286) 

and the base serum (#288). The 

graph to the left displays the 

distributions of these differences 

as smoothed histograms. Note the 

small “bump” on the left tail of the 

#286 - #288 distribution: these five 

values might arise from some 

systematic integration decision 

regarding a partially resolved 

doublet, but we do not yet 

understand what is going on. We 

would appreciate suggestions! 

Augmented - Base Sera	 d) Excluding the five sets of values 

where the total retinol for #286 is Total Retinol, μg/mL suspect, the median difference in 

total retinol for #285 - #288 is 

0.300 μg/mL and for #286 - #288 is 0.275 μg/mL. Given the 1688/1843 = 0.92 ratio between 

the extinction coefficients, this is exactly the expected result. This implies that few if any of 

the participants took into account the reduced extinction coefficient for 13-cis-retinol when 

calculating the total. 

B4
 

 

 

 

 

 

 

 

 

 

4)		 Repeatability. With the exception of total and trans-retinol measurands, Sera #285, #286, and #288 

were intended to be identical. From the summary statistics, all other measurands reported by at least 

ten participants do appear to be the same in all three sera. If you reported results that differ 

significantly (chemically, not statistically) among these three sera, you should re-examine your 

overall measurement process. 

Request 

We need to better understand the chromatography that produced the “halfway between” total retinols 

for serum #286. If your total retinol for #286 is less than 0.20 μg/mL larger then for #288, please 

carefully re-reevaluate the relevant sections of your chromatograms. We would appreciate hearing 

about your analysis and would particularly like to see the chromatogram with annotated integration 

parameters. 

Please note! 

1)		 We prepared a fair large batch of the 13-cis-augmented sera. It will be distributed again, though 

(probably) not in conjunction with both the trans-augmented and base sera. If you need to analyze a 

13-cis-augmented serum again to confirm that you’re indeed measuring what you think you’re 

measuring, let us know before the Nov 4th shipment of RR LIII and we will include it in your 

shipment. 

2)		 It is critical that you carefully inspect all samples on arrival and that you promptly confirm to us that 

they have arrived. We will now replace samples that have been lost or damaged in shipment or mispackaged by us provided that participants report the problem within one calendar week after the 

package’s arrival. 

B5
 

 

 

 

Appendix C. “All-Lab Report” for RR52 

The following five 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 analysts. The NIST results are not used in the assessment of the 

consensus summary results of the study. 

C1
 

 

Round Robin LII Laboratory Results 

All Results in μg/mL 

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

Lab 284 285 286 287 288 

C2

FSV-BA 0.490 0.640 0.538 0.609 0.323 

FSV-BB 0.483 0.607 0.598 0.598 0.315 

FSV-BE 0.560 0.720 0.630 0.680 0.380 

FSV-BF 0.500 0.600 0.470 0.600 0.320 

FSV-BG 0.464 0.597 0.578 0.603 0.303 

FSV-BH 0.442 0.575 0.418 0.558 0.306 

FSV-BI 0.510 0.682 0.647 0.677 0.351 

FSV-BJ 0.472 0.604 0.587 0.591 0.313 

FSV-BK 0.488 0.546 0.554 0.552 0.315 

FSV-BL 0.400 0.570 0.600 0.570 0.290 

FSV-BM 0.481 0.659 0.626 0.660 0.331 

FSV-BN 0.457 0.540 0.544 0.525 0.299 

FSV-BO 0.450 0.636 0.579 0.573 0.329 

FSV-BP 0.496 0.656 0.582 0.637 0.348 

FSV-BQ 0.580 0.690 0.580 0.660 0.380 

FSV-BR >0.530 >0.620 >0.640 >0.340 

FSV-BS >0.356 >0.418 >0.435 >0.208 

FSV-BT 0.437 0.718 0.802 0.676 0.463 

FSV-BU 

FSV-BV 0.546 0.715 0.498 0.696 0.370 

FSV-BW 0.432 0.634 0.616 0.618 0.323 

FSV-BX 0.484 0.637 0.635 0.616 0.333 

FSV-CB 0.493 0.542 0.497 0.523 0.302 

FSV-CC 0.570 0.580 0.560 0.590 0.300 

FSV-CD 0.458 0.583 0.580 0.579 0.317 

FSV-CE 0.472 0.578 0.566 0.577 0.308 

FSV-CF 0.523 0.690 0.502 0.668 0.377 

FSV-CG 0.595 0.678 0.649 0.680 0.361 

FSV-CI 0.410 0.550 0.420 0.530 0.330 

FSV-CL 0.431 0.593 0.564 0.679 0.308 

FSV-CP 

FSV-CR 0.490 0.710 0.650 0.730 0.350 

FSV-CW >0.461 >0.597 0.579 >0.529 >0.326 

FSV-CZ 0.450 0.590 0.600 0.580 0.310 

FSV-DD 0.519 - 0.565 0.594 0.353 

FSV-DF 0.471 0.608 0.582 0.618 0.351 

FSV-DI 0.519 0.789 0.699 0.712 0.384 

FSV-DQ 

FSV-DR 0.480 0.640 0.680 0.640 0.320 

FSV-DW 0.520 0.640 0.590 0.620 0.340 

FSV-EQ 0.445 - 0.546 0.676 0.302 

FSV-ET 0.460 0.550 0.540 0.560 0.270 

FSV-FB 0.460 0.660 0.690 0.570 0.320 

284 285 286 287 288 

0.53 0.62 - 0.64 0.34 

0.356 0.418 0.382 0.435 0.208 

0.484 0.637 0.307 0.616 0.333 

0.530 0.580 0.410 0.590 0.300 

0.461 0.597 0.415 0.529 0.326 

0.471 0.608 0.367 0.618 0.351 

284 285 286 287 288 

0.069 0.017 0.017 0.028 0.016 

0.078 0.014 0.012 0.053 0.011 

0.081 0.028 0.028 0.054 0.024 

0.094 nq nq nq nq 

0.076 nq nq nq nq 

0.072 0.007 0.015 nq 0.007 

0.093 0.008 0.009 0.029 0.007 

0.094 0.020 0.018 0.031 0.019 

0.083 0.013 0.013 0.023 0.015 

0.060 nq nq 0.020 nq 

0.057 0.011 0.009 0.018 0.012 

0.066 0.010 0.014 0.017 0.021 

284 285 286 287 288 

16.97 2.90 2.95 13.41 2.90 

18.01 2.97 2.97 14.16 3.03 

16.00 3.00 2.80 12.30 2.90 

16.90 3.00 2.90 13.30 3.20 

16.70 2.90 2.84 13.50 2.80 

16.66 2.94 2.95 13.44 2.91 

16.66 2.96 2.94 13.62 2.92 

16.86 2.84 2.84 13.83 2.81 

16.30 2.50 2.50 10.80 2.70 

13.78 3.01 3.01 12.49 3.01 

16.00 3.00 3.10 13.10 3.10 

17.38 2.71 2.76 12.33 2.71 

19.10 2.60 3.40 15.10 3.20 

11.47 3.53 3.50 10.61 3.78 

19.50 3.30 3.10 14.30 3.40 

17.47 3.84 3.78 16.50 4.06 

16.41 3.20 3.12 14.78 2.98 

15.80 2.70 2.63 11.92 2.61 

15.83 3.02 2.99 13.35 2.99 

16.62 3.00 3.01 8.68 2.95 

15.48 2.69 2.62 11.65 2.69 

18.73 3.03 3.03 13.91 2.99 

15.64 2.76 2.72 12.29 3.06 

16.26 2.66 3.22 12.29 2.59 

16.90 3.00 2.90 12.90 3.00 

14.48 2.59 2.61 10.13 2.58 

14.90 2.70 2.60 11.40 2.70 

20.45 4.35 4.25 21.23 4.12 

15.07 2.78 2.45 13.22 3.42 

17.10 2.60 2.50 13.40 2.60 

16.28 2.80 2.77 12.81 2.77 

16.20 2.54 2.62 9.30 2.46 

18.19 3.45 3.38 13.98 3.41 

18.14 2.70 2.84 15.80 3.10 

17.76 3.19 3.09 13.24 2.97 

18.30 3.13 2.97 13.50 3.26 

17.20 - 2.80 13.70 2.70 

16.30 2.70 2.70 12.50 2.60 

15.46 4.77 3.49 13.07 3.67 

284 285 286 287 288 

1.63 0.78 0.76 2.24 0.77 

1.52 0.67 0.67 1.98 0.66 

1.60 0.70 0.70 2.10 0.70 

1.70 0.60 0.70 2.30 0.70 

1.56 0.77 0.79 2.21 0.75 

1.34 0.68 0.74 1.79 0.67 

1.65 0.84 0.84 2.30 0.85 

1.56 0.71 0.71 2.25 0.71 

1.50 0.60 0.63 1.80 0.71 

1.51 0.59 0.58 1.86 0.54 

1.65 0.77 0.75 2.19 0.76 

1.65 0.82 0.84 2.45 0.83 

1.52 0.67 0.73 1.73 0.72 

1.60 0.80 0.80 2.10 0.81 

1.72 0.85 0.83 2.47 0.82 

1.50 0.70 0.70 2.20 0.70 

1.91 0.97 0.96 2.83 0.91 

1.65 0.86 0.77 2.57 1.28 

1.61 0.76 0.76 2.20 0.76 

1.67 0.86 0.84 2.37 0.85 

1.67 0.69 0.74 2.66 0.76 

1.40 0.60 0.60 2.10 0.60 

284 285 286 287 

0.527 0.025 0.047 0.119 

0.899 0.116 0.077 0.165 

0.817 0.110 0.094 0.262 

0.680 0.040 0.030 0.120 

0.957 0.067 0.065 0.199 

N 37 35 38 37 37 6 6 5 6 6 12 9 9 9 9 39 38 39 39 39 22 22 22 22 22 5 5 5 5 

Min 0.400 0.540 0.418 0.523 0.270 0.356 0.418 0.307 0.435 0.208 0.057 0.007 0.009 0.017 0.007 11.47 2.50 2.45 8.68 2.46 1.34 0.59 0.58 1.73 0.54 0.527 0.025 0.030 0.119 

Median 0.481 0.634 0.580 0.609 0.323 0.478 0.603 0.382 0.603 0.330 0.077 0.013 0.014 0.028 0.015 16.66 2.95 2.94 13.24 2.97 1.61 0.73 0.75 2.21 0.76 0.817 0.067 0.065 0.165 

Max 0.595 0.789 0.802 0.730 0.463 0.530 0.637 0.415 0.640 0.351 0.094 0.028 0.028 0.054 0.024 20.45 4.77 4.25 21.23 4.12 1.91 0.97 0.96 2.83 1.28 0.957 0.116 0.094 0.262 

SD 0.039 0.065 0.056 0.068 0.032 0.041 0.030 0.032 0.054 0.024 0.013 0.005 0.004 0.008 0.006 1.12 0.24 0.26 1.09 0.33 0.10 0.11 0.07 0.19 0.09 0.163 0.052 0.022 0.059 

CV 8 10 10 11 10 9 5 8 9 7 17 41 27 29 39 7 8 9 8 11 6 15 9 8 12 20 77 35 35 

Npast 46 0 0 0 0 9 0 0 0 0 15 0 0 0 0 49 0 0 0 0 27 0 0 0 0 9 0 0 0 

Medianpast 0.483 0.487 0.082 16.628 1.577 0.738 

SDpast 0.038 0.042 0.020 1.429 0.141 0.350 

NISTa 0.486 0.668 0.691 0.610 0.364 0.486 0.668 0.417 0.610 0.364 17.08 2.98 3.46 12.63 3.11 1.58 1.07 0.97 2.50 0.89 

NISTb 0.497 0.649 0.647 0.637 0.348 0.484 0.644 0.367 0.620 0.348 16.90 2.77 2.80 12.67 2.80 1.52 0.73 0.70 1.96 0.71 0.562 0.056 0.057 0.114 

NNIST 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 2 2 2 2 

Mean 0.492 0.658 0.669 0.624 0.356 0.485 0.656 0.392 0.615 0.356 16.99 2.88 3.13 12.65 2.95 1.55 0.89 0.83 2.23 0.80 0.562 0.056 0.057 0.114 

Srep 0.006 0.026 0.010 0.020 0.009 0.006 0.027 0.008 0.020 0.009 0.52 0.22 0.44 0.19 0.12 0.07 0.05 0.12 0.11 0.05 0.021 0.007 0.008 0.013 

Shet 0.003 0.007 0.003 0.004 0.001 0.003 0.009 0.004 0.007 0.001 0.48 0.14 0.15 0.31 0.09 0.10 0.09 0.06 0.25 0.10 0.043 0.029 0.030 0.013 

Sanl 0.007 0.013 0.031 0.019 0.011 0.002 0.017 0.035 0.007 0.011 0.12 0.15 0.47 0.03 0.22 0.05 0.23 0.19 0.38 0.13 

SNIST 0.010 0.030 0.033 0.028 0.014 0.007 0.033 0.036 0.022 0.014 0.72 0.30 0.66 0.36 0.26 0.13 0.25 0.24 0.47 0.17 0.048 0.030 0.031 0.018 

NAV 0.487 0.647 0.624 0.618 0.340 0.482 0.629 0.387 0.609 0.343 0.076 0.014 0.014 0.029 0.014 16.82 2.97 2.97 12.96 2.97 1.58 0.79 0.79 2.22 0.79 0.690 0.059 0.059 0.140 

NAU 0.043 0.069 0.086 0.070 0.040 0.041 0.061 0.037 0.055 0.033 0.021 0.006 0.006 0.013 0.006 1.31 0.51 0.51 1.19 0.51 0.18 0.24 0.24 0.47 0.24 0.243 0.039 0.039 0.069 

All Lab Report 
 

 

Round Robin LII Laboratory Results 

All Results in μg/mL 

trans-β-Carotene Total cis-β-Carotene Total α-Carotene trans-α-Carotene Total Lycopene trans-Ly

Lab 284 285 286 287 288 

C3

FSV-BA 0.356 0.044 0.042 1.221 0.043 

FSV-BB 0.395 0.047 0.046 1.310 0.044 

FSV-BE 

FSV-BF 

FSV-BG 

FSV-BH 0.417 0.056 0.054 1.445 0.055 

FSV-BI 

FSV-BJ 

FSV-BK 

FSV-BL 

FSV-BM 

FSV-BN 0.402 0.036 0.038 1.325 0.037 

FSV-BO 

FSV-BP 

FSV-BQ 

FSV-BR 

FSV-BS 1.060 0.024 0.007 3.180 0.026 

FSV-BT 0.384 0.062 0.064 1.424 0.060 

FSV-BU 

FSV-BV 

FSV-BW 

FSV-BX 0.389 0.050 0.050 1.330 0.050 

FSV-CB 

FSV-CC 

FSV-CD 

FSV-CE 

FSV-CF 

FSV-CG 0.430 0.047 0.046 1.562 0.046 

FSV-CI 

FSV-CL 

FSV-CP 

FSV-CR 

FSV-CW 0.371 0.048 0.048 1.231 0.048 

FSV-CZ 

FSV-DD 

FSV-DF 

FSV-DI 0.419 0.055 0.053 1.440 0.054 

FSV-DQ 

FSV-DR 

FSV-DW 0.419 0.054 0.048 0.964 0.049 

FSV-EQ 0.344 0.048 0.048 1.341 0.052 

FSV-ET 

FSV-FB 0.320 0.038 0.038 1.260 0.042 

284 285 286 287 288 

0.025 0.002 0.002 0.055 0.002 

0.027 0.002 0.002 0.064 0.003 

0.032 nq nq 0.077 nq 

0.028 nq nq 0.070 nq 

0.034 0.005 0.006 0.089 0.005 

0.026 0.002 0.002 0.073 0.002 

0.029 0.005 0.004 0.064 0.004 

0.062 0.006 0.005 0.074 0.004 

0.008 nq nq nq nq 

0.080 nq nq 0.190 nq 

284 285 286 287 288 

0.085 0.005 0.004 0.029 0.005 

0.093 0.003 0.004 0.031 0.003 

0.105 0.008 0.007 0.034 0.009 

0.098 0.012 0.012 0.042 0.014 

0.100 nq nq 0.033 nq 

0.099 0.004 0.004 0.034 0.004 

0.124 nq nq 0.032 nq 

0.097 nq nq 0.023 nq 

0.130 nq nq 0.044 nq 

0.101 nq nq 0.038 0.013 

0.084 0.009 0.011 0.036 0.009 

0.098 0.003 0.003 0.027 0.004 

0.075 0.005 0.003 0.021 0.004 

0.110 nq nq 0.021 nq 

0.105 0.010 0.009 0.037 0.010 

0.074 0.003 0.002 0.018 0.002 

0.099 0.006 0.005 0.027 0.005 

0.103 0.004 0.003 0.034 0.004 

0.109 0.009 <0.009 - 0.010 

0.075 0.006 0.005 0.025 0.005 

>0.091 >0.005 >0.006 >0.029 >0.007 

0.124 0.003 0.003 0.023 0.003 

0.077 0.002 0.003 0.020 0.002 

0.080 nq nq 0.030 0.005 

284 285 286 287 288 

0.091 0.005 0.006 0.029 0.007 

284 285 286 287 288 

0.425 0.196 0.196 0.422 0.187 

0.429 0.189 0.211 0.449 0.179 

0.463 0.183 0.181 0.365 0.177 

0.474 0.213 0.221 0.484 0.214 

0.350 0.159 0.161 0.378 0.161 

0.498 0.214 0.217 0.489 0.214 

0.420 0.153 0.163 0.394 0.181 

0.555 0.293 0.221 0.580 0.288 

0.504 0.229 0.300 0.390 0.250 

1.040 0.391 0.361 0.841 0.395 

0.397 0.220 0.226 0.434 0.211 

0.386 0.162 0.162 0.395 0.159 

0.461 0.194 0.197 0.437 0.190 

0.373 0.178 0.186 0.408 0.175 

0.299 0.150 0.142 0.338 0.148 

0.487 0.188 0.187 0.474 0.178 

0.427 0.182 0.182 0.461 0.179 

0.377 0.191 0.181 0.460 0.179 

0.423 0.201 0.197 0.412 0.203 

0.346 0.205 0.343 0.368 0.245 

0.338 0.155 0.157 0.351 0.155 

284 285 28

0.244 0.109 0.1

0.204 0.092 0.0

0.254 0.102 0.0

0.226 0.078 0.0

0.405 0.222 0.2

0.167 0.094 0.0

0.180 0.084 0.0

0.226 0.097 0.0

0.178 0.089 0.0

0.300 0.133 0.1

0.223 0.109 0.0

N 13 13 13 13 13 10 6 6 9 6 23 16 15 22 18 1 1 1 1 1 21 21 21 21 21 11 11 

Min 0.320 0.024 0.007 0.964 0.026 0.008 0.002 0.002 0.055 0.002 0.074 0.002 0.002 0.018 0.002 0.299 0.150 0.142 0.338 0.148 0.167 0.078 0.0

Median 0.395 0.048 0.048 1.330 0.048 0.029 0.003 0.003 0.073 0.003 0.099 0.005 0.004 0.030 0.005 0.091 0.005 0.006 0.029 0.007 0.425 0.191 0.196 0.422 0.181 0.226 0.097 0.0

Max 1.060 0.062 0.064 3.180 0.060 0.080 0.006 0.006 0.190 0.005 0.130 0.012 0.012 0.044 0.014 1.040 0.391 0.361 0.841 0.395 0.405 0.222 0.2

SD 0.036 0.008 0.006 0.134 0.007 0.005 0.002 0.002 0.010 0.001 0.015 0.004 0.002 0.008 0.004 0.072 0.026 0.029 0.053 0.027 0.042 0.014 0.0

CV 9 16 13 10 14 18 54 62 13 35 16 73 58 26 78 17 14 15 12 15 19 14 

Npast 15 0 0 0 0 10 0 0 0 0 28 0 0 0 0 0 0 0 0 0 27 0 0 0 0 13 0 

Medianpast 0.382 0.031 0.096 0.406 0.204 

SDpast 0.034 0.010 0.020 0.072 0.036 

NISTa 

NISTb 0.426 0.050 0.054 1.509 0.054 0.043 0.000 0.000 0.083 0.000 0.085 0.004 0.005 0.035 0.008 0.086 0.004 0.005 0.029 0.007 0.472 0.217 0.207 0.465 0.222 

NNIST 2 2 2 2 2 2 1 2 2 2 2 1 2 2 2 2 2 2 2 2 

Mean 0.426 0.050 0.054 1.509 0.054 0.085 0.004 0.005 0.035 0.008 0.086 0.004 0.005 0.029 0.007 0.472 0.217 0.207 0.465 0.222 

Srep 0.007 0.003 0.003 0.020 0.003 0.001 0.000 0.002 0.004 0.002 0.000 0.001 0.002 0.002 0.017 0.013 0.016 0.010 

Shet 0.003 0.001 0.001 0.065 0.002 0.001 0.000 0.007 0.002 0.000 0.000 0.005 0.003 0.000 0.023 0.007 0.021 0.033 

Sanl 

SNIST 0.007 0.003 0.003 0.068 0.004 0.002 0.002 0.008 0.002 0.002 0.005 0.002 0.028 0.015 0.026 0.034 

NAV 0.410 0.050 0.050 1.419 0.050 0.029 0.092 0.005 0.005 0.033 0.005 0.448 0.203 0.203 0.441 0.203 0.226 0.096 0.0

NAU 0.047 0.010 0.010 0.186 0.010 0.010 0.030 0.004 0.004 0.011 0.004 0.097 0.051 0.051 0.096 0.051 0.042 0.017 0.0

All Lab Report 
 

 

Round Robin LII Laboratory Results 

All Results in μg/mL 

Total α-Cryptoxanthin Total Lutein trans-Lutein Total Zeaxanthin Total Lutein & Zeaxanthin C

Lab 284 285 286 287 288 

C4

FSV-BA
 

FSV-BB
 0.014 0.010 0.010 0.030 0.009 

FSV-BE 

FSV-BF 

FSV-BG 

FSV-BH 

FSV-BI 

FSV-BJ 

FSV-BK 

FSV-BL 

FSV-BM 

FSV-BN 0.005 0.001 nq 0.032 nq 

FSV-BO 

FSV-BP 

FSV-BQ 

FSV-BR 

FSV-BS 

FSV-BT 0.032 0.021 0.022 0.055 0.019 

FSV-BU 

FSV-BV 

FSV-BW 

FSV-BX 

FSV-CB 

FSV-CC 

FSV-CD 

FSV-CE 

FSV-CF 

FSV-CG 

FSV-CI 

FSV-CL 0.014 0.013 0.009 0.053 0.010 

FSV-CP 

FSV-CR 

FSV-CW 0.017 0.011 0.011 0.030 0.010 

FSV-CZ 

FSV-DD 

FSV-DF 

FSV-DI 

FSV-DQ 

FSV-DR 

FSV-DW 

FSV-EQ 

FSV-ET 

FSV-FB 

284 285 286 287 288 

0.088 0.044 0.044 0.102 0.042 

0.086 0.048 0.051 0.150 0.047 

0.068 0.036 0.032 0.087 0.036 

0.093 0.048 0.046 0.131 0.046 

0.087 0.044 0.045 0.136 0.047 

0.121 0.059 0.073 0.190 0.069 

0.108 0.076 0.067 0.181 0.074 

0.228 0.091 0.111 0.752 0.095 

0.085 0.061 0.073 0.173 0.066 

0.079 0.044 0.043 0.111 0.046 

- 0.037 0.038 0.077 0.024 

0.102 0.060 0.061 0.166 0.060 

0.070 0.038 0.037 - 0.036 

0.098 0.060 0.061 0.204 0.058 

>0.077 >0.038 >0.038 >0.085 >0.038 

0.093 0.062 0.060 0.169 0.061 

0.100 0.046 0.041 0.130 0.048 

0.085 0.046 0.042 0.101 0.045 

0.049 0.029 0.027 0.069 0.024 

284 285 286 287 288 

0.077 0.038 0.038 0.085 0.038 

284 285 286 287 288 

0.046 0.025 0.026 0.072 0.023 

0.021 0.012 0.022 0.051 0.013 

0.022 0.016 0.016 0.075 0.015 

0.025 0.021 0.020 0.068 0.019 

0.071 0.020 0.034 0.109 0.028 

0.014 0.017 0.015 0.068 nq 

0.032 0.024 0.027 0.058 0.026 

0.018 0.018 0.016 0.060 0.019 

- 0.015 0.016 0.049 0.021 

0.027 0.019 0.019 0.048 0.021 

0.031 0.019 0.019 - 0.019 

0.022 0.021 0.020 0.062 0.019 

0.024 0.019 0.023 0.084 0.021 

0.061 0.037 0.033 0.100 0.037 

0.013 0.015 0.016 0.055 0.014 

284 285 286 287 288 

0.100 0.067 0.055 0.134 0.058 

0.134 0.069 0.069 0.173 0.065 

0.104 0.052 0.058 0.180 0.059 

0.097 0.054 0.063 0.175 0.052 

0.090 0.052 0.048 0.162 0.051 

0.118 0.069 0.066 0.199 0.065 

0.192 0.080 0.107 0.299 0.097 

0.122 0.092 0.083 0.249 >0.074 

0.113 0.088 0.078 0.143 0.070 

0.117 0.085 0.100 0.230 0.092 

0.128 0.074 0.074 0.231 0.075 

0.097 0.058 0.057 0.152 0.058 

0.103 0.061 0.059 0.171 0.064 

0.103 0.051 0.054 0.126 0.045 

0.101 0.051 0.050 0.135 0.053 

0.129 0.079 0.079 0.214 0.081 

0.101 0.057 0.056 - 0.055 

>0.099 >0.059 >0.058 >0.147 >0.057 

0.124 0.065 0.064 0.214 0.069 

0.146 0.083 0.075 0.201 0.082 

0.247 0.138 0.137 0.419 0.112 

0.062 0.044 0.043 0.124 0.038 

284 28

1.200 0.7

0.780 0.5

1.010 0.4

N 5 5 4 5 4 17 18 18 17 18 1 1 1 1 1 14 15 15 14 14 21 21 21 20 20 3 

Min 0.005 0.001 0.009 0.030 0.009 0.049 0.029 0.027 0.069 0.024 0.013 0.012 0.015 0.048 0.013 0.062 0.044 0.043 0.124 0.038 0.780 0.4

Median 0.014 0.011 0.010 0.032 0.010 0.088 0.047 0.046 0.136 0.047 0.077 0.038 0.038 0.085 0.038 0.025 0.019 0.020 0.065 0.020 0.113 0.067 0.064 0.178 0.064 1.010 0.5

Max 0.032 0.021 0.022 0.055 0.019 0.228 0.091 0.111 0.752 0.095 0.071 0.037 0.034 0.109 0.037 0.247 0.138 0.137 0.419 0.112 1.200 0.7

SD 0.002 0.002 0.017 0.012 0.012 0.015 0.053 0.014 0.008 0.004 0.006 0.014 0.003 0.021 0.019 0.016 0.051 0.016 

CV 17 22 53 13 26 32 39 29 32 19 31 21 14 18 29 26 29 25 

Npast 6 0 0 0 0 15 0 0 0 0 0 0 0 0 0 14 0 0 0 0 27 0 0 0 0 0 

Medianpast 0.018 0.083 0.023 0.109 

SDpast 0.007 0.015 0.007 0.025 

NISTa 0.088 0.077 nq 0.145 0.069 nq nq nq 0.055 nq >0.088 >0.077 nq 0.200 >0.069 

NISTb 0.024 0.013 0.014 0.056 0.013 0.078 0.043 0.040 0.095 0.039 0.078 0.043 0.040 0.095 0.039 0.037 0.023 0.021 0.063 0.020 0.115 0.066 0.061 0.158 0.054
 

NNIST 1 1 1 1 1 4 4 2 4 4 2 2 2 2 2 2 2 2 4 2 2 2 2 4 2
 

Mean 0.024 0.013 0.014 0.056 0.013 0.083 0.060 0.040 0.120 0.043 0.078 0.043 0.040 0.095 0.039 0.037 0.023 0.021 0.059 0.009 0.115 0.066 0.061 0.179 0.027
 

Srep 0.002 0.000 0.000 0.000 0.002 0.004 0.004 0.003 0.013 0.004 0.002 0.005 0.003 0.008 0.005 0.002 0.005 0.000 0.006 0.004 0.005 0.009 0.003 0.018 0.009
 

Shet 0.002 0.004 0.006 0.011 0.018 0.002 0.005 0.006 0.013 0.006 0.000 0.004 0.007 0.009 0.013 0.002 0.009 0.013 0.018 0.038
 

Sanl 0.007 0.024 0.035 0.037 0.003 0.007 0.007 0.015 0.007 0.006 0.030
 

SNIST 0.008 0.025 0.007 0.039 0.041 0.002 0.006 0.007 0.012 0.014 0.005 0.013 0.013 0.039 0.039
 

NAV 0.019 0.012 0.044 0.085 0.047 0.047 0.128 0.047 0.031 0.019 0.019 0.062 0.019 0.115 0.059 0.059 0.179 0.059
 

NAU
 0.017 0.030 0.030 0.054 0.030 0.012 0.011 0.011 0.018 0.011 0.024 0.031 0.031 0.048 0.031 

All Lab Report 
 

 

 

 

 

Round Robin LII Laboratory Results
 

All Results in μg/mL
 

Analytes Reported By One Laboratory 

Term 

N 

Min 

Medianpart 

Max 

SD 

CV 

Npast 

Medianpast 

SDpast 

NNIST 

MeanNIST 

Srep 

Shet 

Sanl 

SNIST 

NAV 

NAU 

-

nd 

nq 

>x 

<x 

italics

Analyte Code 284 285 286 287 288 

trans-β-Cryptoxanthin NISTb 0.028 0.014 0.014 0.098 0.05 

trans-Zeaxanthin NISTb 0.037 0.023 0.021 0.063 0.02 

Total Carotenoids FSV-BT 1.116 0.433 0.474 2.477 0.439 

Phytofluene FSV-CL 0.03 0.02 0.02 nq 0.020 

Phytoene FSV-CL 0.07 0.05 0.05 0.06 0.013 

Legend 

Definition

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

 Minimum (non-NIST) quantitative value reported

 Median (non-NIST) quantitative value reported 

 Maximum (non-NIST) quantitative value reported

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

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

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

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

 Pooled SD from past RR(s)
 

 Number of vials analyzed in duplicate by NIST analyst(s)

 Mean of the NIST-analyzed vial means

 W ithin-vial pooled standard deviation

 Among-vial pooled standard deviation

 Between NIST analyst standard deviation 

2

)

0.5 Total standard deviation for NIST analyses: (Srep 2

 + Shet 2 + Sanl 

 NIST Assigned Value

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

 = Medianpart for analytes reported by ≥ 10 labs but not NIST

2

)

0.5 NIST Assigned Uncertainty: (S2

 + Sbtw 

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

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

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

 Not analyzed

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

 Detected but not quantitatively determined

 Concentration greater than x

 Concentration below the limit of quantification, x

 Not explictly reported but calculated by NIST from reported values

All Lab Report Page 4 / 5 

C5
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Round Robin LII Laboratory Results
 

Comparability Summary
 

Lab 

FSV-BA 

FSV-BB 

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-BT 

FSV-BU 

FSV-BV 

FSV-BW 

FSV-BX 

FSV-CB 

FSV-CC 

FSV-CD 

FSV-CE 

FSV-CF 

FSV-CG 

FSV-CI 

FSV-CL 

FSV-CP 

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

1 1 1 1 1 1 1 1 1 1 1 

1 1 1 1 1 1 1 1 1 1 1 1 

2 1 1 1 1 

1 1 1 1 1 1 1 

1 1 1 1 2 1 1 1 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 1 1 1 1 1 1 1 

1 2 

2 2 1 

1 1 

1 1 1 1 1 1 1 1 2 

1 2 3 2 2 3 1 

1 3 3 2 2 3 1 1 1 

2 2 1 

2 2 3 3 

3 1 1 1 2 2 1 1 2 1 1 1 

1 1 1 2 1 1 1 

2 1 1 1 1 1 2 

1 1 1 1 1 1 

1 2 1 1 2 1 1 1 1 1 

2 1 1 1 1 1 

2 1 

1 1 1 1 1 1 1 1 

1 1 1 1 

2 1 1 

2 2 1 1 1 1 1 1 1 

2 2 1 1 2 

1 4 2 1 1 1 1 

1 2 

Label 

Lab 

TR 

aT

g/bT 

bC 

tbC 

aC 

TLy 

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 

trans-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-CR 2 1 1 1 1 

N 2 

FSV-DW 

FSV-EQ 

FSV-ET 

FSV-FB 

NISTa 

NISTb 

n 

% 1 

% 2 

% 3 

% 4 

FSV-DI 2 1 1 1 3 4 

FSV-DQ 2 1 2 1 2 1 

FSV-DR 1 1 2 1 

1 1 2 2 1 2 1 

1 1 1 1 1 1 2 1 2 

1 1 1 1 

1 2 1 2 1 1 

1 1 1 2 1 

1 1 1 1 1 1 1 1 1 1 1 

39 41 24 30 13 24 21 10 24 19 16 22 

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

67 68 92 77 77 75 86 90 71 89 88 86 

31 27 8 13 23 25 14 0 21 11 0 5 

3 2 0 7 0 0 0 10 8 0 13 5 

0 2 0 3 0 0 0 0 0 0 0 5 

CS = 2 C + AP2 + 



 





 FSV-CW 1 1 1 1 1 1 1 1 1 1 N 

FSV-CZ 1 2 4 

FSV-DD 1 i 1 

FSV-DF 1 1 3 1 Nyou 

C = Concordance = 

i 1 

you 



 



 ∑ 

= 

N 

Youi 

NAU 

− 

AP = Apparent Precision = 

i 

 



 

1 

Median 

i 

− 

NAU = NIST Assigned Uncertainty 

you 

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 long-term measurement 

performance. Anal Chem 1999;71(9):1870-8. 

All Lab Report Page 5 / 5 

C6
 

 

 

 

 

Appendix D. Representative “Individualized Report” for RR52 

Each participant in RR52 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 RR52: 

• 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 α-Cryptoxanthin 

• Total Lutein 

• Total Zeaxanthin 

• Total Lutein & Zeaxanthin 

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

participant FSV-BA. 

D1
 

 Set 1 of 45

Individualized Round Robin LII Report: FSV-BA 

Summary 

Serum 284 Serum 285 Serum 286 Serum 287 

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

Total Retinol 0.490 0.487 38 0.640 0.647 36 0.538 0.624 39 0.609 0.618 38 

Retinyl Palmitate 0.07 0.08 12 0.0 0.0 9 0.0 0.0 9 0.03 0.03 9 

α-Tocopherol 16.97 16.82 39 2.90 2.97 38 2.95 2.97 39 13.41 12.96 39 

γ/β-Tocopherol 1.634 1.581 22 0.776 0.788 22 0.755 0.788 22 2.240 2.222 22 

Total β-Carotene 0.381 0.437 29 0.046 0.054 28 0.044 0.054 28 1.276 1.458 27 

trans-β-Carotene 0.356 0.410 13 0.044 0.050 12 0.042 0.050 12 1.221 1.419 13 

Total cis-β-Carotene 0.025 0.029 10 0.002 6 0.002 6 0.055 9 

Total α-Carotene 0.085 0.092 23 0.005 0.005 16 0.004 0.005 15 0.029 0.033 22 

trans-Lycopene 0.244 0.226 11 0.109 0.096 11 0.107 0.096 11 0.235 0.192 11 

Total β-Cryptoxanthin 0.038 0.033 23 0.023 0.016 23 0.021 0.016 23 0.116 0.113 23 

Total Lutein&Zeaxanthin 0.100 0.115 21 0.067 0.059 21 0.055 0.059 21 0.134 0.179 20 

D2

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

NAV : NIST Assigned Value, equal to (NIST's average-of-averages + this RR's median) / 2
 

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 45

Individualized RR LII Report: FSV-BA 

Total Retinol 

Apparent Precision, SD 

[Analyte], μg/mL 

249256264284287288285286 

Your [Analyte], μg/mL

Apparent Precision, SD 

Median [Analyte], μg/mL 

Concordance, SD Long-term Precision, SD 

3rd Quartile (75%) 

You, this RR You, >x, this RR NIST, this RR Median (50%) 

You, >x, past RRs 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.
 

Serum History Comments 

#284 #249 RR44, #256 RR46, #264 RR48 SRM 968c Level II 

#285 New, fresh-frozen Same pool as #288 & ~0.3 μg/mL trans-retinol 

#286 New, fresh-frozen Same pool as #288 & ~0.3 μg/mL 13-cis-retinol 

#287 New, fresh-frozen Native serum, high in many measurands 

#288 New, fresh-frozen Native serum, low in most measurands 

 Individualized Report Page 2 / 10 

D3
 

 

 

 Set 1 of 45

Individualized RR LII Report: FSV-BA 

α-Tocopherol 

Apparent Precision, SD 

[Analyte], μg/mL 

249256264284287288285286 

Your [Analyte], μg/mL

Apparent Precision, SD 

Median [Analyte], μg/mL 

Concordance, SD 

3rd Quartile (75%) 

You, this RR You, >x, this RR 

Long-term Precision, SD 

Median (50%) NIST, this RR 

1st Quartile (25%) 

You, >x, past RRs You, past RRs Others, this RR 

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 

#284 #249 RR44, #256 RR46, #264 RR48 SRM 968c Level II 

#285 New, fresh-frozen Same pool as #288 & ~0.3 μg/mL trans-retinol 

#286 New, fresh-frozen Same pool as #288 & ~0.3 μg/mL 13-cis-retinol 

#287 New, fresh-frozen Native serum, high in many measurands 

#288 New, fresh-frozen Native serum, low in most measurands 

 Individualized Report Page 2 / 10 

D4
 

 

 

 Set 1 of 45

Individualized RR LII Report: FSV-BA 

γ/β-Tocopherol 

Apparent Precision, SD 

[Analyte], μg/mL 

249256264284287288285286

Your [Analyte], μg/mL

Apparent Precision, SD 

Median [Analyte], μg/mL 

Concordance, SD 

3rd Quartile (75%) 

You, this RR You, >x, this RR 

Long-term Precision, SD 

Median (50%) NIST, this RR 

1st Quartile (25%) 

You, >x, past RRs You, past RRs Others, this RR 

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 

#284 #249 RR44, #256 RR46, #264 RR48 SRM 968c Level II 

#285 New, fresh-frozen Same pool as #288 & ~0.3 μg/mL trans-retinol 

#286 New, fresh-frozen Same pool as #288 & ~0.3 μg/mL 13-cis-retinol 

#287 New, fresh-frozen Native serum, high in many measurands 

#288 New, fresh-frozen Native serum, low in most measurands 

 Individualized Report Page 2 / 10 

D5
 

 

 

 Set 1 of 45

Individualized RR LII Report: FSV-BA 

Total β-Carotene 

Apparent Precision, SD 

[Analyte], μg/mL 

249256264284287288285286 

Your [Analyte], μg/mL

Median [Analyte], μg/mL 

Apparent Precision, SD 

Concordance, SD Long-term Precision, SD 

3rd Quartile (75%) 

You, this RR You, >x, this RR 

Median (50%) NIST, this RR 

1st Quartile (25%) 

You, >x, past RRs You, past RRs Others, this RR 

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 

#284 #249 RR44, #256 RR46, #264 RR48 SRM 968c Level II 

#285 New, fresh-frozen Same pool as #288 & ~0.3 μg/mL trans-retinol 

#286 New, fresh-frozen Same pool as #288 & ~0.3 μg/mL 13-cis-retinol 

#287 New, fresh-frozen Native serum, high in many measurands 

#288 New, fresh-frozen Native serum, low in most measurands 

 Individualized Report Page 2 / 10 

D6
 

 

 

 Set 1 of 45

Individualized RR LII Report: FSV-BA 

trans-β-Carotene 

Apparent Precision, SD 

[Analyte], μg/mL 

249256264284287288285286 

Your [Analyte], μg/mL

Median [Analyte], μg/mL 

Apparent Precision, SD 

Concordance, SD Long-term Precision, SD 

3rd Quartile (75%) 

You, this RR You, >x, this RR 

Median (50%) NIST, this RR 

1st Quartile (25%) 

You, >x, past RRs You, past RRs Others, this RR 

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 

#284 #249 RR44, #256 RR46, #264 RR48 SRM 968c Level II 

#285 New, fresh-frozen Same pool as #288 & ~0.3 μg/mL trans-retinol 

#286 New, fresh-frozen Same pool as #288 & ~0.3 μg/mL 13-cis-retinol 

#287 New, fresh-frozen Native serum, high in many measurands 

#288 New, fresh-frozen Native serum, low in most measurands 

 Individualized Report Page 2 / 10 

D7
 

 

 

 Set 1 of 45

Individualized RR LII Report: FSV-BA 

Total α-Carotene 

Apparent Precision, SD 

[Analyte], μg/mL 

249256264284287288285286 

Your [Analyte], μg/mL

Median [Analyte], μg/mL 

Apparent Precision, SD 

Concordance, SD Long-term Precision, SD 

3rd Quartile (75%) 

You, this RR You, >x, this RR 

Median (50%) NIST, this RR 

1st Quartile (25%) 

You, >x, past RRs You, past RRs Others, this RR 

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 

#284 #249 RR44, #256 RR46, #264 RR48 SRM 968c Level II 

#285 New, fresh-frozen Same pool as #288 & ~0.3 μg/mL trans-retinol 

#286 New, fresh-frozen Same pool as #288 & ~0.3 μg/mL 13-cis-retinol 

#287 New, fresh-frozen Native serum, high in many measurands 

#288 New, fresh-frozen Native serum, low in most measurands 

 Individualized Report Page 2 / 10 

D8
 

 

 

 Set 1 of 45

Individualized RR LII Report: FSV-BA 

trans-Lycopene 

Apparent Precision, SD 

[Analyte], μg/mL 

249256264284287288285286

Your [Analyte], μg/mL

Apparent Precision, SD 

Median [Analyte], μg/mL 

Concordance, SD 

3rd Quartile (75%) 

You, this RR You, >x, this RR 

Long-term Precision, SD 

Median (50%) NIST, this RR 

1st Quartile (25%) 

You, >x, past RRs You, past RRs Others, this RR 

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 

#284 #249 RR44, #256 RR46, #264 RR48 SRM 968c Level II 

#285 New, fresh-frozen Same pool as #288 & ~0.3 μg/mL trans-retinol 

#286 New, fresh-frozen Same pool as #288 & ~0.3 μg/mL 13-cis-retinol 

#287 New, fresh-frozen Native serum, high in many measurands 

#288 New, fresh-frozen Native serum, low in most measurands 

 Individualized Report Page 2 / 10 

D9
 

 

 

 Set 1 of 45

Individualized RR LII Report: FSV-BA 

Total β-Cryptoxanthin 

Apparent Precision, SD 

[Analyte], μg/mL 

249256264284287288285286

Your [Analyte], μg/mL

Median [Analyte], μg/mL 

Apparent Precision, SD 

Concordance, SD Long-term Precision, SD 

3rd Quartile (75%) 

You, this RR You, >x, this RR 

Median (50%) NIST, this RR 

1st Quartile (25%) 

You, >x, past RRs You, past RRs Others, this RR 

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 

#284 #249 RR44, #256 RR46, #264 RR48 SRM 968c Level II 

#285 New, fresh-frozen Same pool as #288 & ~0.3 μg/mL trans-retinol 

#286 New, fresh-frozen Same pool as #288 & ~0.3 μg/mL 13-cis-retinol 

#287 New, fresh-frozen Native serum, high in many measurands 

#288 New, fresh-frozen Native serum, low in most measurands 

 Individualized Report Page 2 / 10 

D10
Set 1 of 45 

Individualized Round Robin LII Report: FSV-BA
 

Graphical Comparability Summary
 

Total Retinol α-Tocopherol Total β-Carotene 

D11

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 Co

Individualized Report 
 

 

 

Appendix E. Shipping Package Inserts for RR17 

The following five items were included in each package shipped to an RR17 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
Dear Colleague: 

UNITED STATES DEPARTMENT OF COMMERCE 

National Institute of Standards and Technology 

Gaithersburg, Maryland 20899-0001 

June 14, 2002 

Enclosed are samples for the second Vitamin C Round Robin 17 (RRl 7) of the 2002 Micronutrients 

Measurement Quality Assurance Program. This study is provided to you at no additional cost 

through financial support from the Centers for Disease Control and Prevention. 

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. 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). 

RRl 7 consists of three vials of frozen serum (test samples) and one vial of solid ascorbic acid 

(control sample). Please follow the attached protocol when you prepare and analyze these samples. 

If you cannot prepare the control sample solutions gravimetrically, please prepare equivalent 

solutions volumetrically and report the exact volumes used. 

Please be reminded that sample contact with any oxidant-contaminated surface (sample 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, particularly of your calibration solutions and/or control samples. 

We ask that you return your results for these RRl 7 samples using the attached form before 

September 30, 2002. Your results will be kept confidential. 

If you have any questions or concerns please contact Jeanice Brown Thomas at tel: 301-975-3120, 

fax: 301-977-0685, or e-mail: jbthomas@nist.gov. 

e · ce Brown omas 

R search Chemist 

Enclosures 

Sam Margolis, Ph.D. 

Research Chemist 

E2
 

 

 

 

 

 

 

 

NIST/CDC Micronutrient Measurement Quality Assurance Program 

Please Read Through Completely BEFORE Analyzing Samples 

Protocol for Preparation and Analysis of the Control Sample 

The control sample consists of a sample of solid ascorbic acid in an amber vial. It 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 0.18 to 0.22 g of the solid ascorbic acid sample 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 of the sample 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
 

 

 

 

 

 

 

 

 

 

dL (A )⋅((g AA in Stock Solution )	 + (g Diluent in Stock Solution )) 1% max 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 you will use for the test samples, 

including any enzymatic treatment. Compare the replicate values. Are you satisfied that your 

measurement precision is adequate? Do not evaluate the test samples until you are satisfied that 

your system is performing properly! 

7.		 Compare the measured with the calculated [TAA] DS 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 evaluate the test samples until you are satisfied that your system is performing 

properly! 

Protocol for Analysis of the Test Samples 

The test samples are in sealed ampoules. They were prepared by adding equal volumes of 10% 

metaphosphoric acid 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 test samples should be defrosted by warming at 20 °C for not more than 10 min otherwise some 

irreversible degradation may occur. 

Each 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 17 

NIST/CDC Micronutrient Measurement Quality Assurance Program 

Preparation and Validation of Control Samples 

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 September 30, 2002 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 17 

NIST/CDC Micronutrient Measurement Quality Assurance Program 

Analysis of Control 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 

Test Sample #21 μmol/L of Sample 

Test Sample #34 μmol/L of Sample 

Test Sample #53 μmol/L of Sample 

Were samples frozen upon receipt? Yes | No 

Was SRM 970 used to validate your method or value-assign your in-house controls? Yes | No 

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

If “Other”, please describe: 

COMMENTS: 

Please return by September 30, 2002 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 17
 

NIST/CDC Micronutrients Measurement Quality Assurance Program
 

Packing List and Shipment Receipt Confirmation Form
 

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

Sample Form 

VitC #21 Liquid frozen (1:1 serum:10% MPA) 

VitC #34 Liquid frozen (1:1 serum:10% MPA) 

VitC #53 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 samples VitC:1, VitC:11, and VitC:51 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 four vials intact? Yes | No 

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

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

4) Did samples VitC #21, VitC #34, and VitC #53 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 RR17 

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
November 20, 2002 

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 for Round Robin 17 (RRl 7) 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 eSD/median. 

RRl 7 consists of three unknowns (test samples) and one solid reference ascorbic acid for 

preparation of 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-

3730. If your measured values do not agree with the certified values, we suggest that you contact us 

for consultation. 

Samples for the 2003 QA vitamin C round robin study (RR 18) were shipped on November 18. If 

you have not received these samples, please contact us immediately. The results for RR 18 are due 

by March 3, 2003. 

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. 

~Utcerely, . · ~ 6~ 

ice Brown Thomas 

earch Chemist 

Analytical Chemistry Division 

Chemical Science and Technology Laboratory 

Enclosures 

NlSI 

F2
 

 

 

 

 

 

 

 

 

 

 

 

 

 

The NIST/CDC M2QAP Vitamin C Round Robin 17 (RR17) report consists of 

Page “Individualized” Report 

1 Tabular summary of your reported values for the nominal 55 mmol/L solution you prepared 

from the solid ascorbic acid control sample and for three recently prepared test samples. 

2 Graphical summary of your RR 17 sample measurements. 

3 Graphical summary of your RR 17 control solution measurements. 

Page “All Lab” Report 

1 Tabular summary of results and statistics for Total Ascorbic Acid [TAA] in the RR17 

samples and control/calibration solutions. 

Test Samples. Three unknowns were distributed in RR17. 

Three unknowns (Sera 21. 34, and 53) were distributed in RR17. Each serum sample was prepared 

from a serum pool augmented with solid, high-purity ascorbic acid. 

Qualitative Observations. 

1)		 All participants successfully prepared the four control/calibration solutions (the three dilute solutions 

and the 5% metaphosphoric acid (MPA) diluent). 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 A.U.), the calculated E1% #1”(≈590 

dL/g·cm), and the extent of correlation between the expected and observed [TAA] for the four 

solutions (R2

 of 0.99 or better). 

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 all participants appear to be well 

calibrated. The overall among-participant agreement (concordance) was only slightly improved by 

correcting the reported test sample results with the observed calibration parameters. 

Quantitative Results 

As shown in Figure 1, the interlaboratory estimated standard deviations (eSD) of both the test and 

control/calibration measurements appear to be linear functions of the median [TAA]. (These robust 

estimates of the location and dispersion of the measurement distributions are less sensitive to atypical 

values then are the mean and standard deviations. (See Robust Statistics - How Not to Reject Outliers 1. 

Basic Concepts, ANALYST 1989;114(12):1693-1697.) While the eSD is linearly related to the median, 

the estimated coefficient of variance (eCV, 100×eSD/median) is not constant (see inset) for either the 

test or control samples. This suggests that the observed interlaboratory measurement dispersions have 

both measurand-dependent and measurand-independent sources. The observed eSD for the test sample 

measurements are much larger than those for the control/calibration solutions. These observations will 

be addressed in future “Round Robin” studies. 

F3
Figure 1. 

5
 

4
 

eSD, mmol/L 

3
 

2
 

1
 

0 

0 10 20 30 40 50 

Median, mmol/L 

RR16 Control 

RR17 Control 

RR16 Sample 

RR17 Sample 

0 

5 

10 

15 

20 

0 10 20 30 40 50 

Median, mmol/L 

eCV, % 

F4
 

 

 

 

 

 

Appendix G. “All-Lab Report” for RR17 

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 Ac

"Round Robin" 17 - September 2002 

Control / Calibration Samples MPA Dilute Solution 1 

G2

Measu

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

E1% Lab Date Dil:1 Dil:2 Dil:3 Dil:1 Dil:2 Dil:3 MPA Inter Slope R2 SEE g/mL S17:1 S

λmax Amax 

VC-MA 12/12/02 56.9 28.5 14.2 60.1 30.2 14.2 0.0 -0.32 1.06 1.000 0.5 1.030 242. 0.5521 551.0 9.5 

VC-MB 01/07/02 56.9 29.7 14.8 54.5 30.0 19.5 0.0 2.41 0.93 0.989 2.9 1.031 244. 0.5457 544.0 15.0 

VC-MC 01/07/02 51.5 24.7 12.9 50.7 24.9 12.4 0.0 0.02 0.99 1.000 0.4 1.031 243. 0.4847 534.7 8.4 

VC-ME 30/09/02 55.1 27.8 13.5 56.0 28.8 14.3 0.7 0.75 1.00 1.000 0.1 1.030 244. 0.5651 582.6 8.9 

VC-MG 11/10/02 57.2 28.4 13.9 58.6 29.4 15.2 0.0 0.43 1.02 1.000 0.5 1.030 243.6 0.544 539.5 11.7 

VC-MH 11/10/02 58.8 29.4 14.6 57.8 28.8 14.4 0.0 -0.01 0.98 1.000 0.1 1.030 243.1 0.5987 578.2 9.3 

VC-MI 05/09/02 60.3 30.9 15.0 62.1 32.8 16.4 0.0 0.58 1.03 1.000 0.7 1.028 13.5 

VC-MO 27/09/02 57.8 27.5 13.5 56.8 27.9 13.8 1.3 1.12 0.96 1.000 0.3 1.029 243. 0.5549 545.5 10.0 

VC-MQ 31/10/02 54.1 27.1 13.7 58.2 29.3 14.6 0.0 -0.06 1.08 1.000 0.1 1.029 244. 0.547 574.4 9.4 

VC-MR 03/07/02 56.0 29.3 14.5 56.0 28.0 14.0 0.0 -0.44 1.00 0.999 0.8 1.030 244. 0.533 540.8 9.0 

VC-MT 05/09/02 56.0 27.6 14.3 58.2 24.8 12.3 0.0 -1.79 1.05 0.994 2.3 1.028 243.5 0.5655 572.9 15.6 

VC-MY 08/08/02 57.4 29.8 14.4 64.8 31.5 15.6 0.0 -0.64 1.13 0.999 1.2 1.031 244. 0.555 548.6 7.1 

VC-NH 23/09/02 55.7 27.8 13.8 56.7 28.0 13.8 0.0 -0.18 1.02 1.000 0.2 1.031 242.5 0.5624 573.0 8.4 

NIST 15/10/02 56.1 27.6 13.8 56.6 28.8 14.5 0.0 0.41 1.01 1.000 0.5 1.029 243. 0.5428 549.1 9.2 

N 13 13 13 13 N 13 12 12 12 13 

Average 57.7 28.8 14.6 0.2 Average 1.030 243.4 0.5507 557.1 10.4 

SD 3.5 2.3 1.8 0.4 SD 0.001 0.7 0.0264 17.5 2.7 

Min 50.7 24.80 12.3 0.0 Min 1.028 242.0 0.4847 534.7 7.1 

%25 56.0 27.95 13.8 0.0 %25 1.029 243.0 0.5453 543.2 8.9 

Median 57.8 28.80 14.3 0.0 Median 1.030 243.6 0.5535 549.8 9.4 

%75 58.6 30.00 15.2 0.0 %75 1.031 244.0 0.5631 573.3 11.7 

Max 64.8 32.85 19.5 1.3 Max 1.031 244.0 0.5987 582.6 15.6 

eSD 2.6 1.35 0.7 0.0 eSD 0.001 0.7 0.0136 18.8 1.4 

CV 4 5 5 CV 0.09 0.27 2 3 15 

All Lab Report 
Appendix H. Representative “Individualized Report” for RR17 

Each participant in RR17 received an “Individualized Report” reflecting their reported 

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

“VC-MA”. 

H1
 

Set 1 of 14 

Vitamin C 'Round Robin' 17 Report: Participant VC-MA
 

MPA Dilute Solution 1 Control/Calibration Solutions 

Density Spectrophotometry Ymeas = Inter + Slope* Xgrav 

R2 Date RR Method g/mL 

1.030 

1.031 

1.028 

1.027 

1.032 

1.026 

λmax Amax E1% 

243.0 0.072 

244.0 0.523 572.5 

243.0 0.541 547.7 

243.0 0.547 556.5 

242.0 0.575 576.5 

242.0 0.552 551.0 

Inter Slope SEE 

04/02/99 12 HPLC-EC 

09/17/01 13 HPLC-EC 

09/27/01 14 HPLC-EC -0.9 1.03 0.999 1.09 

09/18/01 15 HPLC-EC 0.0 1.04 1.000 0.05 

11/18/02 16 HPLC-EC -0.4 1.07 0.999 0.90 

12/12/02 17 HPLC-EC -0.3 1.06 1.000 0.49 

Mean 1.029 242.8 0.47 560.8 

SD 0.002 0.8 0.19 12.9 

CV 0.23 0.31 41.6 2.3 

[TAA] mmol/Lsample
 

RR Sample
 

17 S17:1
 

Rep1 Rep2 Fadj Mean SDdup 

9.9 9.1 1.0 9.5 0.6 

17 S17:2 23.3 23.4 1.0 23.4 0.1 

16 S16:3
 

17 S17:3
 

N Mean SDrepeat SDreprod 

49.9 44.9 1.0 47.4 3.5 2 48.4 2.5 2.3 

49.7 49.1 1.0 49.4 0.4 

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 

H2
 

 

 

Set 1 of 14 

Vitamin C 'Round Robin' 17 Report: Participant VC-MA 

Total Ascorbic Acid 

S17:1S17:2S16:3S17:3 

[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 17 NIST, RR 17 Median (50%) You, RR 12-16 Others, RR 12-16 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 

S17:1 Serum 21, augmented to 9.1 μmol/L sample 

S17:2 Serum 34, augmented to 23.8 μmol/L sample 

S17:3 Serum 53, augmented to 47.9 μmol/L sample. Distributed as S16:3 in RR 16. 

Individualized Report Page 2 / 2 

H3