NISTIR 7880-9

NIST Micronutrients Measurement 

Quality Assurance Program 

Winter 2008 

Comparability Studies 

Results for Round Robin LXIII 

Fat-Soluble Vitamins and Carotenoids in Human Serum 

and Round Robin 28 Ascorbic Acid in Human Serum 

David L. Duewer 

Jeanice B. Thomas 

 

 

 

NISTIR 7880-9
 

NIST Micronutrients Measurement 

Quality Assurance Program 

Winter 2008 

Comparability Studies 

Results for Round Robin LXIII 

Fat-Soluble Vitamins and Carotenoids in Human Serum 

and Round Robin 28 Ascorbic Acid in Human Serum 

David L. Duewer 

Jeanice B. Thomas 

Chemical Sciences Division 

Materials Measurement Laboratory 

April, 2013 

U.S. Department of Commerce 

Rebecca Blank, Acting Secretary 

National Institute of Standards and Technology 

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

ii
 
 

Abstract 

The National Institute of Standards and Technology coordinates the Micronutrients Measurement 

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

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

Winter 2008 MMQAP measurement comparability improvement studies: 1) Round Robin LXIII FatSoluble Vitamins and Carotenoids in Human Serum and 2) Round Robin 28 Total Ascorbic Acid in 

Human Serum. The materials for both studies were shipped to participants in November 2007; 

participants were requested to provide their measurement results by March 3, 2008. 

Keywords 

Human Serum
 

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

SRM 968d, SRM 1950
 

Total Ascorbic Acid
 

iii 
 

 

 

 

 

 

 

 

Table of Contents 

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

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

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

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

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

Round Robin 28: Vitamin C in Human Serum............................................................................... 2
 

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

Appendix A. Shipping Package Inserts for RR63........................................................................ A1
 

Appendix B. Final Report for RR63 ..............................................................................................B1
 

Appendix C. “All-Lab Report” for RR63 ......................................................................................C1
 

Appendix D. Representative “Individualized Report” for RR63 ............................................... D1
 

Appendix E. Shipping Package Inserts for RR28 ......................................................................... E1
 

Appendix F. Final Report for RR28............................................................................................... F1
 

Appendix G. “All-Lab Report” for RR28..................................................................................... G1
 

Appendix H. Representative “Individualized Report” for RR28............................................... 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 LXIII: Fat-Soluble Vitamins and Carotenoids in Human Serum 

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

LXIII comparability study (hereafter referred to as RR63) received eight liquid-frozen 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 2007. 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 RR63 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 28: Vitamin C in Human Serum 

Participants in the MMQAP Vitamin C in Human Serum Round Robin 28 comparability study 

(hereafter referred to as RR28) received four frozen serum test samples, one frozen control serum, 

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

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

dry ice to participants in November 2007. 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 RR28 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 RR63 

The following three items were included in each package shipped to an RR63 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
UNn'ED STATES DEPARTMENT OF COMMERCE 

National Institute of Standards and Technology 

Gaithersburg, Maryland 20899-

November 5, 2007 

Dear Colleague: 

Enclosed are the samples (Sera 339-346) for the first fat-soluble vitamins and carotenoids in serum round 

robin study (Round Robin LXIII) for the fiscal year 2008 NIST Micronutrients Measurement Quality 

Assurance Program. You will find one vial of each of eight liquid-frozen 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 3, 

2008. Results received more than two weeks after the due date will not be included in the summary 

report for this round robin study. 

To ensure adequate mixing of the samples, we recommend 3 to 5 min agitation in an ultrasonic bath or 

about 10 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. Water should not be added to 

the liquid-frozen samples. 

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

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

(ethanol), 2592 at 452 nm (hexane); lycopene, 3450 at 4 72 nm (hexane). 

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

Micronutrients Measurement Quality Assurance Program 

NIST 

l 00 Bureau Drive Stop 8392 

Gaithersburg, MD 20899-8392 

Fax: (301) 977-0685 

If you have questions or comments regarding this study, please call me at (301) 975-3120; e-mail me at 

jbthomas@nist.gov; or mail/fax queries to the above address. 

Q~; Qy__! 

na ical Chemistry Division 

mical Science and Technology Laboratory 

Enclosures 

NISI 

A2
 

 

Participant #: ________ 

Round Robin LXIII: Human Sera 

NIST Micronutrients Measurement Quality Assurance Program 

A3

Analyte 339 340 341 342 343 344 345 

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

 total coenzyme Q10 

phylloquinone (K1) 

25-hydroxyvitamin D 

Other measurands? 

Comments: 

Mail: M2QAP
 

NIST, Stop 8392 Please return results before 

Gaithersburg, MD 20899-8392 March 3, 2008 Ema
 

 

 

 

Participant #: ________ Date: _____________ 

Fat-Soluble Vitamins Round Robin LXIII
 

NIST Micronutrients Measurement Quality Assurance Program
 

Packing List and Shipment Receipt Confirmation Form 

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

Serum Form Reconstitute? Vial & Cap 

#339 Liquid frozen No 2 mL amber, green 

#340 Liquid frozen No 2 mL amber, silver 

#341 Liquid frozen No 10 mL amber, silver 

#342 Liquid frozen No 10 mL amber, red 

#343 Liquid frozen No 10 mL amber, green 

#344 Liquid frozen No 10 mL amber, silver 

#345 Liquid frozen No 10 mL amber, red 

#346 Liquid frozen No 10 mL amber, green 

Please 1) Open the pack immediately 

2) Check that it contains all of the above samples 

3) Check if the vials are intact 

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

5) Complete the following information 

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

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

1) Date this shipment arrived: ___________________________ 

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

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

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

4) Did the liquid frozen samples arrive frozen? Yes | No 

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

6) When do you anticipate analyzing these samples? ________________________ 

Your prompt return of this information is appreciated. 

The M2QAP Gang 

Mail: M2QAP 

NIST, Stop 8392 Fax: 301-977-0685 

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

A4
 

 

Appendix B. Final Report for RR63 

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
May 2, 2008 

Dear Colleague: 

. 

UNrrED STATES DEPARTMENT OF COMMERCE 

Nat:ionai Institute of Standards and Technology 

Gaithel'$burg, Maryland 20899-

Enclosed is the summary report of the results for round robin LXIII (RR63) of the 2008 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 comparability. 

We apologize for distributing four samples, sera #342, 343, 345, and 346 that proved to be quite 

heterogeneous in ~-carotene. We have elected to exclude all results for these sera from further analysis, 

on the basis of possible heterogeneity in other analytes and that the observed low levels of mosf analytes 

in these materials are amply represented by the other RR63 samples. Sera {342, 345} and {343, 346} 

were each duplicates of two different serum pools, the first from the beginning of their bottling runs and 

the second from the end. 

The "All Lab" and "Individualized" reports present results only for the other four RR63 samples, Sera 

339, 340, 341and343. Your overall measurement comparability is summarized in the "Score Card" 

summary, page 5 of the All Lab Report. Combined results rated 1to3 are within 1 to'3 standard 

deviations of the assigned value, respectively; those rated 4 are >3 standard deviations from the assigned 

value. Similar information is presented graphically in the "target plots" that are the last page of your · 

Individualized Report. If you have concerns regarding your laboratory's performance, please contact us 

for consultation. 

Samples for the second 2008 QA interlaboratory exercise will be shipped starting the week of May 19, 

2008. We will send you a reminder via e-mail or fax a week prior to shipment. It is critical that you 

careful~y inspect all samples upon arrival and that you promptly confirm to us that they have arrived. We 

will replace samples (lost or damaged in shipment or miss-packaged by us) only for participants who 

report the problem within one calendar week after the package arrives. 

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 

search Chemist 

Analytical Chemistry Division 

Chemical Science and Technology Laboratory 

Cc: L.C. Sander 

D.L. Duewer 

N51 

B2
 

 

 

 

 

 

The NIST M2QAP Round Robin LXI (RR63) report consists of: 

Page 

1-3 A listing of all results and statistics for all analytes. 

4 A legend for the list of results and statistics. 

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

Page “Individualized” Report 

1 

2 to 

n 

n+1 

Samples. 

Serum 

339 

340 

341 

342 

343 

344 

345 

346 

“All Lab” Report 

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

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

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

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

Eight samples were distributed in RR63. 

Description 

Fresh-frozen, native, single-donor serum prepared at 

NIST in Spring, 2006. 

Fresh-frozen, native, multi-donor plasma 

commercially prepared in Spring 2007. 

Fresh-frozen, native, multi-donor serum prepared in 

Fall, 2007. Vial from beginning of bottling run. 

Fresh-frozen, augmented in α-tocopherol and βcarotene, multi-donor serum prepared in Fall, 2007. 

Vial from beginning of bottling run. 

Fresh-frozen; augmented in retinol, α-tocopherol, 

γ-tocopherol, and β-carotene; multi-donor serum 

prepared in Fall, 2007. Vial from beginning of 

bottling run. 

Duplicate of #341; vial from end of bottling run. 

Duplicate of #342; vial from end of bottling run. 

Duplicate of #343; vial from end of bottling run. 

Prior Distributions 

#326:RR60-9/06, #331:RR61-3/07, 

#338:RR62-9/07 

Heterogeneous in (at least) 

β-carotene. Results not used. 

Heterogeneous in (at least) 

β-carotene. Results not used. 

Results not used. 

Results not used. 

Results 

1)	 Sample Heterogeneity: Figure 1 plots the ratio of the observed standard deviation (SD, estimated 

from the median absolute deviation from the median) to the SD expected from past results. The 

variability of β-carotene in sera {342,345} and {344,346} is many times that expected. While the 

variability of α-tocopherol is greater than expected for all of the RR63 samples, it is perhaps 

significantly higher for the augmented {342,345} and {344,346} than it is for the three native 

materials. There is no clear heterogeneity signal for the other analytes, but several (retinol, 

B3
 

 

γ/β-tocopherol, β-cryptoxanthin, and lutein&zeaxanthin) are equivocal. While the commercial 

preparer had achieved apparently homogenous β-carotene augmentation in several trial samples, it is 

clear that they were unable to scale up their process. The β-carotene in sera {342,345} and 

{344,346} appears to be largely in the form of globules of various size. These globules quite 

plausibly may have differentially absorbed some of other spiked compounds and/or the target 

analytes native to the materials. Given the generally low native levels of the target analytes in sera 

{342,345} and {344,346}, we chose to disregard all results for these samples. 

9 

SD Ratio, Observed / Expected

8 

7 

6 

5 

4 

3 

2 

1 

0 

Serum 339
 

Plasma 340
 

Sera{ 341,344} 

Sera {342,345} 

Sera {344,346} 

Total Retinol

trans-Retinol

Retinyl Palmitate

a-Tocopherol

g/b-Tocopherol

Total b-Carotene

trans-b-Carotene

Total a-Carotene

Total Lycopene

trans-Lycopene

Total b-Cryptoxanthin

Total Lutein

Total Zeaxanthin

Total Lutein&Zeaxanthin

Coenzyme Q10 

Figure 1: Heterogeneity Analysis, Observed SD / Expected SD, 

for Analytes Having Seven or More Reported Results 

2)	 Sera Stability. There was no significant change in the median level of any measurand in the freshfrozen serum #339. There was no significant change in the measurement variability of any 

measurand in this material, with the possible exception of α-tocopherol. Since the α-tocopherol 

variability in plasma 340 and sera {341, 344} was also above historical expectations, this more likely 

reflects changes in the measurement processes used rather than the sample materials. We intend to 

explore in greater detail the results from the recent past to see if this increased variability is a “once 

off” or an evolving trend. 

B4
3)	 Plasma vs. serum. Plasma #340 is Candidate SRM 1950, Metabolites in Human Plasma. There were 

no analysis problems reported for this material. Your results will contribute to establishing reference 

and information values for the “Fat Soluble” measurands in this material. We hope to make this 

material available as an SRM soon. 

4)	 Sera {341,344}: The sera {341, 344} material was intended to be the “Low Level” component of 

SRM 968d Fat-Soluble Vitamins and Carotenoids in Human Serum. Unfortunately, the intended 

“Middle” and “High” level components proved to be quite unacceptable. While resource constraints 

have delayed developing replacement materials for this quite high-priority SRM, we intend to make 

the {341,344} “Low” material available in some form. From our evaluation of the entire bottling run 

and from your evaluations of samples from the first and last of the run, the serum pool for Sera 341 

and 344 appears to be adequately homogenous in all measurands. One laboratory, however, 

indicated that the level of α-tocopherol for these sera was near their limit of quantification. We will 

continue to look into this issue. 

B5
 

Appendix C. “All-Lab Report” for RR63 

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 LXIII Laboratory Results 

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

Lab 339 340 341 344 

C2

FSV-BA 0.330 0.430 0.349 0.363 

FSV-BB 0.295 0.413 0.345 0.338 

FSV-BC 0.331 0.459 0.361 0.361 

FSV-BD 0.300 0.405 0.339 0.308 

FSV-BE 0.305 0.423 0.339 0.336 

FSV-BF 0.280 0.430 0.350 0.330 

FSV-BG 0.298 0.409 0.348 0.348 

FSV-BH 0.334 0.378 0.309 0.275 

FSV-BI 0.288 0.401 0.336 0.327 

FSV-BJ 0.280 0.402 0.326 0.336 

FSV-BK 0.372 0.509 0.408 0.412 

FSV-BL 0.230 0.320 0.260 0.260 

FSV-BM 0.326 0.392 0.331 0.359 

FSV-BN 0.289 0.388 0.308 0.313 

FSV-BO 0.306 0.441 0.433 0.398 

FSV-BP 0.333 0.431 0.357 0.337 

FSV-BQ 0.344 0.465 0.379 0.394 

FSV-BR ≥0.300 ≥0.440 ≥0.310 ≥0.280

≥0.285 ≥0.368 ≥0.309 ≥0.313 FSV-BS 

≥0.272 ≥0.437 ≥0.384 ≥0.314 FSV-BT 

FSV-BU 0.301 0.428 0.317 0.354 

FSV-BV 0.291 0.422 0.339 0.345 

FSV-BW 0.310 0.430 0.350 0.360 

FSV-CC 0.325 0.420 0.353 0.334 

FSV-CD 0.320 0.430 0.350 0.360 

FSV-CE 0.314 0.434 0.354 0.359 

FSV-CF 0.380 0.489 0.393 0.399 

FSV-CG 0.307 0.413 0.339 0.322 

FSV-CI ≥0.303 ≥0.455 ≥0.363 ≥0.381

FSV-CW 0.258 0.485 0.353 0.385 

FSV-CZ 0.430 0.566 0.459 0.449 

FSV-DD 0.270 0.380 0.310 0.300 

FSV-DI 0.256 0.374 0.297 0.301 

FSV-DQ 

FSV-DV ≥0.282 ≥0.371 ≥0.288 ≥0.287

FSV-EE 0.279 0.370 0.305 0.271 

FSV-EZ ≥0.230 ≥0.404 ≥0.537 ≥0.420

339 340 341 344 

0.300 0.440 0.310 0.280 

0.285 0.368 0.309 0.313 

0.272 0.437 0.384 0.314 

0.312 0.405 0.351 0.322 

0.303 0.455 0.363 0.381 

0.282 0.371 0.288 0.287 

0.230 0.404 0.537 0.420 

339 340 341 344 

0.058 0.022 0.030 0.029 

0.010 0.013 0.007 0.007 

0.009 0.012 0.009 0.008 

0.019 0.026 0.014 0.016 

0.009 0.013 0.006 0.004 

0.026 0.018 0.017 0.016 

0.010 0.016 0.007 nq 

0.032 0.010 0.010 0.024 

339 340 341 344 

8.25 8.01 5.87 6.02 

8.34 8.14 5.96 5.78 

8.90 8.80 7.40 6.10 

7.68 7.61 5.08 5.01 

8.80 9.20 4.80 2.80 

8.34 7.89 5.96 5.95 

7.87 7.65 5.53 5.25 

8.13 8.00 5.86 5.91 

8.81 8.65 6.25 6.36 

8.91 8.59 5.90 6.14 

7.30 7.30 5.20 5.20 

8.10 8.40 6.10 6.30 

8.33 7.47 4.80 5.33 

9.20 8.50 6.70 6.20 

7.45 6.74 4.56 5.14 

7.74 7.14 5.65 5.24 

8.30 7.40 nq nq 

7.73 7.60 5.32 12.17 

7.30 6.54 4.75 4.95 

8.50 8.82 5.30 5.51 

8.80 8.55 6.15 6.44 

8.46 8.29 5.75 5.90 

10.05 9.47 6.62 6.16 

9.45 9.13 6.27 6.37 

7.57 7.51 4.83 5.05 

9.10 9.00 6.60 6.40 

7.70 7.65 1.13 nd 

7.56 7.60 5.09 5.76 

10.75 10.48 6.35 5.82 

5.28 6.21 2.73 2.93 

8.85 8.94 6.55 6.48 

7.63 7.15 4.35 4.99 

8.60 7.80 4.70 4.80 

8.50 8.50 5.70 5.70 

8.23 7.52 5.41 5.99 

339 340 341 344 

3.65 1.77 1.48 1.55 

3.33 1.66 1.38 1.35 

3.83 1.88 1.54 1.49 

3.70 2.00 1.50 1.30 

3.76 1.73 1.54 1.48 

3.29 1.58 1.31 1.26 

3.66 1.83 1.48 1.58 

3.64 1.78 1.41 1.45 

3.67 1.81 1.53 1.57 

3.70 1.90 1.50 1.60 

2.29 1.41 1.15 1.96 

3.02 1.31 1.10 1.13 

3.58 1.67 1.30 1.29 

3.61 1.79 1.46 1.50 

3.59 1.67 1.55 1.52 

3.71 1.77 1.43 1.44 

3.70 1.86 1.43 1.35 

3.20 1.89 1.25 1.38 

5.14 2.46 1.96 1.89 

2.58 1.00 0.77 0.81 

3.25 1.70 1.40 1.36 

3.98 1.83 1.32 1.49 

3.69 1.73 1.43 1.59 

339 34

0.089 0.0

0.093 0.0

nd n

0.130 0.1

0.068 0.0

N 29 29 29 29 7 7 7 7 8 8 8 7 35 35 34 33 23 23 23 23 4 

Min 0.230 0.320 0.260 0.260 0.230 0.368 0.288 0.280 0.009 0.010 0.006 0.004 5.28 6.21 1.13 2.80 2.29 1.00 0.77 0.81 0.07 0

Median 0.306 0.423 0.348 0.345 0.285 0.405 0.351 0.314 0.014 0.015 0.010 0.016 8.33 8.00 5.68 5.82 3.65 1.77 1.43 1.48 0.09 0

Max 0.430 0.566 0.459 0.449 0.312 0.455 0.537 0.420 0.058 0.026 0.030 0.029 10.75 10.48 7.40 12.17 5.14 2.46 1.96 1.96 0.13 0

SD 0.031 0.024 0.017 0.025 0.018 0.038 0.047 0.038 0.013 0.005 0.006 0.009 0.81 0.82 0.92 0.71 0.29 0.13 0.14 0.16 0.01 0

CV 10 6 5 7 6 9 14 12 92 32 60 58 10 10 16 12 8 7 10 11 15 

Npast 32 0 0 0 5 0 0 0 8 0 0 0 34 0 0 0 22 0 0 0 5 

Medianpast 0.307 0.305 0.021 8.486 3.673 0.086 

SDpast 0.025 0.030 0.019 0.514 0.322 0.076 

NIST 0.295 0.407 0.331 0.331 8.62 7.95 6.33 6.33 3.71 1.82 1.47 1.47
 

NNIST 3 10 14 14 3 10 14 14 3 10 14 14
 

Srep 0.008 0.011 0.011 0.011 0.105 0.208 0.245 0.245 0.052 0.045 0.044 0.044
 

Shet 0.011 0.005 0.007 0.007 0.088 0.263 0.225 0.225 0.019 0.024 0.046 0.046
 

SNIST 0.013 0.012 0.013 0.013 0.136 0.335 0.332 0.332 0.055 0.051 0.064 0.064
 

NAV 0.301 0.415 0.342 0.342 0.285 0.405 0.351 0.351 0.014 0.015 0.010 0.010 8.475 7.977 5.941 5.941 3.682 1.796 1.461 1.461 0.091 0.0

NAU 0.032 0.036 0.030 0.030 0.024 0.038 0.047 0.047 0.013 0.011 0.011 0.011 0.835 0.820 0.923 0.923 0.339 0.192 0.164 0.164 

All Lab Report 
 

Round Robin LXIII Laboratory Results 

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

Lab 339 340 341 344 

C3

FSV-BA 0.148 0.077 0.080 0.085 

FSV-BB 0.133 0.080 0.083 0.081 

FSV-BC 

FSV-BD 

FSV-BE 0.159 0.076 0.072 0.065 

FSV-BF 

FSV-BG 0.153 0.086 0.087 0.088 

FSV-BH 0.114 0.063 0.059 0.055 

FSV-BI 0.123 0.068 0.075 0.075 

FSV-BJ 0.150 0.082 0.085 0.084 

FSV-BK 

FSV-BL 

FSV-BM 

FSV-BN 0.147 0.070 0.071 0.076 

FSV-BO ≥0.166 ≥0.083 ≥0.088 ≥0.105

FSV-BP 0.150 0.060 0.060 0.070 

FSV-BQ 

FSV-BR 

FSV-BS ≥0.117 ≥0.069 ≥0.077 ≥0.073

FSV-BT 0.124 0.080 0.104 0.077 

FSV-BU 0.141 0.068 0.079 0.079 

FSV-BV 0.148 0.075 0.078 0.078 

FSV-BW 0.167 0.077 0.064 0.064 

FSV-CC 

FSV-CD 0.220 0.190 0.190 0.170 

FSV-CE 0.116 0.056 0.064 0.059 

FSV-CF 

FSV-CG 0.135 0.075 0.074 0.071 

FSV-CI 0.136 0.060 0.067 0.083 

FSV-CW 0.112 0.059 0.040 0.056 

FSV-CZ 0.157 0.116 0.104 0.108 

FSV-DD 

FSV-DI 0.133 0.050 0.067 0.067 

FSV-DQ 0.165 0.072 0.060 0.071 

FSV-DV 

FSV-EE 

FSV-EZ ≥0.116 ≥0.061 ≥0.066 ≥0.076

339 340 341 344 

0.141 0.074 0.076 0.080 

0.126 0.074 0.077 0.075 

0.114 0.063 0.059 0.055 

0.139 0.065 0.063 0.067 

0.166 0.083 0.088 0.105 

0.117 0.069 0.077 0.073 

0.114 0.073 0.091 0.068 

0.126 0.068 0.074 0.070 

0.116 0.061 0.066 0.076 

339 340 341 344 

0.006 0.004 0.004 0.005 

0.007 0.006 0.005 0.006 

nq nq nq nq 

0.005 0.003 0.004 0.005 

0.010 0.007 0.013 0.009 

0.009 0.007 nd nd 

339 340 341 344 

0.013 0.025 0.009 0.007 

0.010 0.022 0.007 0.008 

0.015 0.027 0.012 0.013 

0.010 0.022 0.009 0.007 

0.014 0.030 nq 0.011 

0.011 0.023 0.009 0.010 

0.022 0.027 nd 0.013 

nd 0.024 nd nd 

0.018 0.026 0.018 0.014 

0.012 0.022 0.009 0.006 

0.016 0.027 0.009 0.010 

nq nq nq nq 

0.030 0.070 0.030 0.030 

0.017 0.031 0.009 0.009 

0.035 0.031 0.028 0.033 

0.008 0.031 0.005 0.008 

0.038 0.034 0.010 0.008 

339 340 341 344 

0.581 0.313 0.290 0.314 

0.548 0.334 0.287 0.280 

0.578 0.344 0.293 0.289 

0.482 0.289 0.226 0.216 

0.416 0.250 0.235 0.226 

0.576 0.320 0.274 0.294 

0.542 0.293 0.186 0.205 

0.789 0.464 0.426 0.424 

0.264 0.336 0.306 0.238 

0.409 0.247 0.236 0.205 

0.457 0.308 0.330 0.254 

0.552 0.278 0.271 0.269 

0.611 0.332 0.288 0.279 

0.730 0.370 0.200 0.240 

0.580 0.440 0.430 0.390 

0.556 0.325 0.263 0.198 

0.687 0.340 0.338 0.330 

0.497 0.285 0.229 0.274 

339 34

0.323 0.1

0.261 0.1

0.315 0.1

0.293 0.1

0.224 0.1

0.309 0.1

0.240 0.1

N 21 21 21 21 9 9 9 9 5 5 4 4 15 16 13 15 18 18 18 18 7 

Min 0.112 0.050 0.040 0.055 0.114 0.061 0.059 0.055 0.005 0.003 0.004 0.005 0.008 0.022 0.005 0.006 0.264 0.247 0.186 0.198 0.224 0.1

Median 0.147 0.075 0.074 0.076 0.126 0.069 0.076 0.073 0.007 0.006 0.005 0.006 0.015 0.027 0.009 0.010 0.554 0.323 0.281 0.272 0.293 0.1

Max 0.220 0.190 0.190 0.170 0.166 0.083 0.091 0.105 0.010 0.007 0.013 0.009 0.038 0.070 0.030 0.033 0.789 0.464 0.430 0.424 0.323 0.1

SD 0.015 0.013 0.014 0.012 0.017 0.007 0.008 0.006 0.002 0.002 0.002 0.001 0.006 0.005 0.002 0.004 0.070 0.036 0.050 0.047 0.046 0.0

CV 10 17 19 16 14 10 11 8 32 37 42 19 40 20 25 37 13 11 18 17 16 

Npast 21 0 0 0 10 0 0 0 6 0 0 0 19 0 0 0 19 0 0 0 7 

Medianpast 0.145 0.131 0.009 0.016 0.582 0.288 

SDpast 0.018 0.015 0.004 0.006 0.068 0.044 

NIST 0.147 0.078 0.077 0.077 0.028
 

NNIST 3 10 14 14 10
 

Srep 0.001 0.002 0.002 0.002 0.002
 

Shet 0.001 0.002 0.003 0.003 0.002
 

SNIST 0.002 0.003 0.003 0.003 0.003
 

NAV 0.147 0.077 0.075 0.075 0.126 0.069 0.076 0.076 0.007 0.006 0.005 0.005 0.015 0.027 0.009 0.009 0.554 0.323 0.281 0.281 0.293 0.1

NAU 0.023 0.014 0.014 0.014 0.017 0.010 0.011 0.011 0.003 0.003 0.006 0.009 0.004 0.004 0.112 0.072 0.065 0.065 0.053 0.0

All Lab Report 
Round Robin LXIII Laboratory Results 

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

Lab 339 340 341 344 

C4

FSV-BA 0.105 0.034 0.038 0.043 

FSV-BB 0.098 0.036 0.040 0.039 

FSV-BC 

FSV-BD 

FSV-BE 

FSV-BF 

FSV-BG 0.116 0.038 0.045 0.045 

FSV-BH 0.110 0.036 0.039 0.038 

FSV-BI 0.097 0.032 0.039 0.039 

FSV-BJ 0.108 0.036 0.038 0.042 

FSV-BK 

FSV-BL 

FSV-BM 

FSV-BN 0.102 0.027 0.025 0.026 

FSV-BO 0.107 0.034 0.037 0.037 

FSV-BP 0.109 0.069 0.037 0.040 

FSV-BQ 

FSV-BR 

FSV-BS 

FSV-BT 0.086 0.034 0.038 0.034 

FSV-BU 0.113 0.030 0.041 0.041 

FSV-BV 0.109 0.035 0.040 0.040 

FSV-BW 0.140 0.049 0.048 0.040 

FSV-CC 

FSV-CD 0.670 0.280 0.290 0.310 

FSV-CE 

FSV-CF 

FSV-CG 0.134 0.048 0.053 0.049 

FSV-CI 

FSV-CW 0.108 0.040 0.042 0.045 

FSV-CZ 

FSV-DD 

FSV-DI 

FSV-DQ 0.104 0.039 0.031 0.037 

FSV-DV 

FSV-EE 

FSV-EZ 

339 340 341 344 

0.036 0.014 0.015 0.018 

0.031 0.014 0.015 0.015 

0.028 0.007 0.005 0.006 

0.029 0.015 0.016 0.014 

0.120 0.060 0.070 0.070 

339 340 341 344 

0.162 0.072 0.063 0.061 

0.151 0.086 0.077 0.078 

0.118 0.056 0.043 0.045 

0.125 0.052 0.042 0.044 

0.135 0.062 0.054 0.056 

0.185 0.079 0.062 0.063 

0.176 0.078 0.081 0.079 

0.171 0.058 0.053 0.065 

0.174 0.092 0.086 0.094 

0.144 0.059 0.052 0.054 

0.183 0.068 0.069 0.059 

339 340 341 344 

0.079 0.032 0.032 0.031 

0.035 0.017 0.017 0.016 

0.080 0.023 0.024 0.024 

0.075 0.027 0.028 0.028 

0.075 0.021 0.016 0.013 

0.053 0.022 0.028 0.021 

0.047 0.017 0.024 0.029 

0.037 0.014 0.019 0.022 

0.065 0.021 0.025 0.024 

339 340 341 344 

0.237 0.089 0.073 0.078 

0.241 0.105 0.095 0.092 

0.169 0.095 0.086 0.086 

0.198 0.079 0.067 0.069 

0.200 0.079 0.070 0.072 

0.276 0.102 0.079 0.076 

0.2292 0.0995 0.1092 0.0995 

0.215 0.150 0.132 0.131 

0.270 0.069 0.040 0.046 

0.295 0.156 0.152 0.134 

0.245 0.084 0.089 0.088 

0.240 0.098 0.088 0.088 

0.250 0.107 0.088 0.090 

0.610 0.170 0.160 0.180 

0.276 0.111 0.097 0.094 

0.218 0.075 0.077 0.094 

0.210 0.106 0.105 0.116 

0.248 0.089 0.094 0.083 

339 340 

1.351 0.78

1.190 0.66

1.200 0.80

0.880 0.51

1.449 1.09

1.160 0.68

1.278 0.79

1.060 0.57

N 17 17 17 17 5 5 5 5 11 11 11 11 9 9 9 9 18 18 18 18 8 

Min 0.086 0.027 0.025 0.026 0.028 0.007 0.005 0.006 0.118 0.052 0.042 0.044 0.035 0.014 0.016 0.013 0.169 0.069 0.040 0.046 0.880 0.51

Median 0.108 0.036 0.039 0.040 0.031 0.014 0.015 0.015 0.162 0.068 0.062 0.061 0.065 0.021 0.024 0.024 0.241 0.099 0.089 0.089 1.195 0.73

Max 0.670 0.280 0.290 0.310 0.120 0.060 0.070 0.070 0.185 0.092 0.086 0.094 0.080 0.032 0.032 0.031 0.610 0.170 0.160 0.180 1.449 1.09

SD 0.007 0.004 0.003 0.004 0.005 0.001 0.001 0.003 0.026 0.015 0.015 0.012 0.021 0.004 0.007 0.005 0.037 0.016 0.019 0.014 0.120 0.11

CV 6 12 8 9 17 5 5 20 16 22 25 20 32 21 28 22 15 16 21 16 10 1

Npast 19 0 0 0 4 0 0 0 13 0 0 0 11 0 0 0 19 0 0 0 6 

Medianpast 0.107 0.039 0.147 0.062 0.213 1.133 

SDpast 0.023 0.009 0.034 0.016 0.050 0.107 

NIST 0.232 0.102 0.079 0.079 0.083 0.039 0.025 0.025 0.165 0.083 0.054 0.054 0.067 0.019 0.025 0.025 

NNIST 3 10 14 14 3 10 14 14 3 10 14 14 3 10 14 14 

Srep 0.004 0.003 0.003 0.003 0.006 0.004 0.004 0.004 0.002 0.002 0.004 0.004 0.007 0.005 0.005 0.005 

Shet 0.004 0.003 0.002 0.002 0.004 0.004 0.004 0.004 0.004 0.001 0.002 0.002 0.008 0.005 0.004 0.004 

SNIST 0.006 0.004 0.004 0.004 0.007 0.006 0.005 0.005 0.005 0.002 0.004 0.004 0.010 0.006 0.007 0.007 

NAV 0.096 0.038 0.035 0.035 0.031 0.014 0.015 0.015 0.163 0.076 0.059 0.059 0.066 0.020 0.024 0.024 0.236 0.101 0.086 0.086 1.195 0.73

NAU 0.030 0.009 0.014 0.014 0.005 0.001 0.003 0.003 0.029 0.018 0.015 0.015 0.021 0.006 0.007 0.007 0.051 0.021 0.020 0.020 0.120 0.11

All Lab Report 
 

Round Robin LXIII Laboratory Results 

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

C5

Lab 339 340 341 344 339 340 341 344 339 340 341 344 339 340 341 344 

FSV-BA 0.011 0.024 0.014 0.013 

FSV-BB 

FSV-BC 

FSV-BD 

FSV-BE 0.629 0.557 0.284 0.244 

FSV-BF 

FSV-BG 

FSV-BH 0.023 0.007 0.013 0.015 

FSV-BI 

FSV-BJ 

FSV-BK 

FSV-BL 

FSV-BM 

FSV-BN 

FSV-BO 

FSV-BP 

FSV-BQ 

FSV-BR 

FSV-BS 

FSV-BT 

FSV-BU 

FSV-BV 

FSV-BW 0.890 0.270 nd nq 0.310 0.390 0.390 0.330 

FSV-CC 

FSV-CD 

FSV-CE 

FSV-CF 

FSV-CG 

FSV-CI 0.620 0.520 0.220 0.200 

FSV-CW 

FSV-CZ 

FSV-DD 

FSV-DI 1.350 0.767 0.210 0.130 0.180 0.210 0.618 0.700 0.280 0.230 0.130 0.190 

FSV-DQ 

FSV-DV 

FSV-EE 

FSV-EZ 

N 2 2 1 1 2 2 2 2 3 3 3 3 2 2 2 2 

Min 0.890 0.270 0.180 0.210 0.390 0.330 0.280 0.230 0.130 0.190 0.011 0.007 0.013 0.013 

Median 1.120 0.519 0.210 0.130 0.245 0.300 0.504 0.515 0.620 0.520 0.220 0.200 0.017 0.015 0.013 0.014 

Max 1.350 0.767 0.310 0.390 0.618 0.700 0.629 0.557 0.284 0.244 0.023 0.024 0.014 0.015 

SD 

CV 

Npast 0 0 0 0 0 0 0 0 0 0 0 0 9 0 0 0 

Medianpast 0.008 

SDpast 0.001 

NIST
 

NNIST
 

Srep
 

Shet
 

SNIST
 

NAV 0.620 0.520 0.220 0.220
 

NAU
 

All Lab Report 
 

Round Robin LXIII Laboratory Results
 

Term 

N

Min

Median

Max

SD

CV

Npast

Medianpast

SDpast

NIST 

NNIST 

Srep 

Shet 

SNIST 

NAV

NAU

-

nd

nq

≤x

italics

Legend 

 Number of quantitative values reported for this analyte 

 Minimum quantitative value reported 

 Median quantitative value reported 

 Maximum quantitative value reported 

 Standard deviation for results: (Median Absolute Difference from the median)/0.674 

 Coefficient of Variation for 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) 

Average of NIST measurements 

Number of sample units analyzed by NIST 

NIST repeatability standard deviation 

Material homogeniety 

SQRT(SUMSQ(Srep,Shet)) 

 NIST Assigned Value: Median 

 NIST Assigned Uncertainty: Max(0.05*NAV, SNIST, SD, eSD). 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 at or below the limit of quantification, x 

 Not explictly reported but calculated by NIST from reported values 

All Lab Report Page 5 / 6 

C6
 

 

 

 

 

 

 

 

Round Robin LXIII Laboratory Results
 

Comparability Summary
 

Lab 

FSV-BA 

FSV-BB 

FSV-BC 

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-BT 

FSV-BU 

FSV-BV 

FSV-BW 

FSV-CC 

FSV-CD 

FSV-CE 

FSV-CF 

FSV-CG 

FSV-CI 

FSV-CW 

FSV-CZ 

FSV-DD 

FSV-DI 

FSV-DQ 

FSV-DV 

FSV-EE 

FSV-EZ 

NIST 

n 

% 1
 

% 2
 

% 3
 

% 4
 

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

1 1 1 1 1 1 1 1 1
 

1 1 1 1 1 1 1 1 1 2 1
 

1
 

1 2
 

1 1 1 1
 

1 3 1
 

1 1 1 1 1 1 1 1 2 1
 

2 1 2 2 2 1 1 2 1 1
 

1 1 1 1 1 1 1 2 1 1
 

1 1 1 1 1 1 1 1
 

3 1
 

3 1
 

1 1
 

2 1 1 1 1 1 1 1 1 2 1
 

2 1 1 2 3 1 3 1 1 1 1
 

1 2 1 2 2 3
 

2 1
 

2 1
 

2 4 4 1 1 2 2
 

2 2 3 2 1 2 1 1 3
 

1 1 1 1 1 1 1 1
 

1 1 1 1 1 1 1 1
 

1 1 1 1 2 1 1
 

1 2
 

1 2 1 4 4 2 4 4
 

1 1 2
 

2 1
 

1 1 1 1 1 1 1 1 1
 

1 1 2 1 4 1 1 1
 

2 3 4 2 1 1 2 1 1
 

4 4 4 3
 

2
 

2 1 1 2 1 1
 

2 1 1 3 1 1 1 1 1
 

2 1
 

2 1
 

4 1 1 1
 

1 1 1 1 1 1 1 1
 

36 36 24 24 9 15 18 18 12 10 19
 

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

56 69 75 67 78 73 72 89 75 70 79
 

33 17 8 25 11 7 22 6 25 30 5
 

6 6 4 4 11 7 6 0 0 0 11
 

6 8 13 4 0 13 0 6 0 0 5
 

Label

Lab 

TR 

aT 

g/bT

bC 

tbC 

aC 

TLy 

TbX 

TLu 

TZ 

L&Z

n 

% 1 

% 2 

% 3 

% 4 

 Definition 

 Participant code 

 Total Retinol 

α-Tocopherol 

 γ/β-Tocopherol 

 Total β-Carotene 

 trans-β-Carotene 

 Total α-Carotene 

 Total Lycopene 

Total β-Cryptoxanthin 

 Total Lutein 

 Total Zeaxanthin 

 Total Lutein & Zeaxanthin 

 number of participants providing quantitative data 

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

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

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

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

“Comparability Score” 

The Comparability Score (CS) of summarizes your measurement 

performance for a given measurand, relative to the consensus 

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

that your measurement performance characteristics are from the 

consensus performance. CS is calculated when the number of 

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

two and the measurand has been reported by 10 or more 

participants. 

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

∑

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

i NAU i
 

N yo u  You i − Median i 

2
 

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

NAU = NIST Assigned Uncertainty, our estimate of the overall

measurement standard deviation for each sample. The 

estimate includes serum heterogeneity, analytical 

repeatability, and among-participant reproducibility variance 

components. 

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

KE, Brown Thomas J, Gary KT. Micronutrients Measurement 

Quality Assurance Program: Helping participants use 

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

All Lab Report Page 6 / 6
 

C7
 

Appendix D. Representative “Individualized Report” for RR63 

Each participant in RR63 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 RR63: 

• Total Retinol 

• trans-Retinol 

• Retinyl Palmitate 

• α-Tocopherol 

• γ/β-Tocopherol 

• Total β-Carotene 

• trans-β-Carotene 

• Total α-Carotene 

• Total Lycopene 

• trans-Lycopene 

• Total β-Cryptoxanthin 

• Total α-Cryptoxanthin 

• Total Lutein 

• Total Zeaxanthin 

• Total Lutein&Zeaxanthin 

• Coenzyme Q10 

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

by participant FSV-BA. 

D1
 

 Set 1 of 38 

Individualized Round Robin LXIII Report: FSV-BA 

Summary 

Serum 339 Serum 340 Serum 341 Serum 344 

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

Total Retinol 0.330 0.301 31 0.430 0.415 31 0.349 0.342 31 0.363 0.342 31 

Retinyl Palmitate 0.06 0.01 9 0.0 0.0 9 0.0 0.0 9 0.03 0.01 8 

α-Tocopherol 8.25 8.47 36 8.01 7.98 36 5.87 5.94 34 6.02 5.94 34 

γ/β-Tocopherol 3.651 3.682 24 1.774 1.796 24 1.479 1.461 24 1.552 1.461 24 

δ-Tocopherol 0.089 0.091 5 0.085 0.080 5 0.081 0.084 6 0.086 0.084 6 

Total β-Carotene 0.148 0.147 22 0.077 0.077 22 0.080 0.075 22 0.085 0.075 22 

trans-β-Carotene 0.141 0.126 9 0.074 0.069 9 0.076 0.076 9 0.080 0.076 9 

Total cis-β-Carotene 0.006 0.007 5 0.004 0.006 5 0.004 0.005 4 0.005 0.005 4 

Total α-Carotene 0.013 0.015 16 0.025 0.027 17 0.009 0.009 14 0.007 0.009 16 

Total Lycopene 0.581 0.554 18 0.313 0.323 18 0.290 0.281 18 0.314 0.281 18 

trans-Lycopene 0.323 0.293 8 0.165 0.149 8 0.138 0.115 8 0.148 0.115 8 

Total β-Cryptoxanthin 0.105 0.096 18 0.034 0.038 18 0.038 0.035 18 0.043 0.035 18 

Total α-Cryptoxanthin 0.036 0.031 5 0.014 0.014 5 0.015 0.015 5 0.018 0.015 5 

Total Lutein&Zeaxanthin 0.237 0.236 19 0.089 0.101 19 0.073 0.086 19 0.078 0.086 19 

25-hydroxyvitamin D 0.011 2 0.024 2 0.014 2 0.013 2 

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 Tel: (301) 975-3935 

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

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

Individualized Report Page 1 / 13 

D2
 

NIST, this RR

 

 Set 1 of 38 

Individualized RR LXIII Report: FSV-BA

Total Retinol, μg/mL 

Apparent Precision, SD [Analyte], μg/mL

326331338339340341344

Your [Analyte], μg/mL 

Median [Analyte], μg/mL 

Apparent Precision, SD 

Long-term Precision, SD 

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

1st Quartile (25%) Expectation 

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

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

Serum History Comments 

#339 Fresh frozen: 60:#326, 61:#331, 62:#338 Native, single-source 

#340 Fresh frozen: New Native, multiple-source 

#341 Fresh frozen: New, from beginning of production Native, single-source 

#344 Same as #341, but from end of production run Native, single-source 

Concordance, SD 

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

Individualized Report Page 2 / 13 

D3
NIST, this RR

 

 Set 1 of 38 

Individualized RR LXIII Report: FSV-BA

Retinyl Palmitate, μg/mL 

[Analyte], μg/mL

Your [Analyte], μg/mL 

Median [Analyte], μg/mL 

Apparent Precision, SD 

326331338339340341344 

Apparent Precision, SD 

Long-term Precision, SD 

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

1st Quartile (25%) Expectation 

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

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

Serum History Comments 

#339 Fresh frozen: 60:#326, 61:#331, 62:#338 Native, single-source 

#340 Fresh frozen: New Native, multiple-source 

#341 Fresh frozen: New, from beginning of production Native, single-source 

#344 Same as #341, but from end of production run Native, single-source 

Concordance, SD 

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

Individualized Report Page 3 / 13 

D4
NIST, this RR

 

 Set 1 of 38 

Individualized RR LXIII Report: FSV-BA

α-Tocopherol, μg/mL 

[Analyte], μg/mL

Your [Analyte], μg/mL 

Median [Analyte], μg/mL 

Apparent Precision, SD 

326331338339340341344 

Apparent Precision, SD 

Long-term Precision, SD 

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

1st Quartile (25%) Expectation 

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

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

Serum History Comments 

#339 Fresh frozen: 60:#326, 61:#331, 62:#338 Native, single-source 

#340 Fresh frozen: New Native, multiple-source 

#341 Fresh frozen: New, from beginning of production Native, single-source 

#344 Same as #341, but from end of production run Native, single-source 

Concordance, SD 

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

Individualized Report Page 4 / 13 

D5
NIST, this RR

 

 Set 1 of 38 

Individualized RR LXIII Report: FSV-BA

γ/β-Tocopherol, μg/mL 

[Analyte], μg/mL

Your [Analyte], μg/mL 

Median [Analyte], μg/mL 

Apparent Precision, SD 

326331338339340341344 

Apparent Precision, SD 

Long-term Precision, SD 

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

1st Quartile (25%) Expectation 

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

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

Serum History Comments 

#339 Fresh frozen: 60:#326, 61:#331, 62:#338 Native, single-source 

#340 Fresh frozen: New Native, multiple-source 

#341 Fresh frozen: New, from beginning of production Native, single-source 

#344 Same as #341, but from end of production run Native, single-source 

Concordance, SD 

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

Individualized Report Page 5 / 13 

D6
NIST, this RR

 

 Set 1 of 38 

Individualized RR LXIII Report: FSV-BA

Total β-Carotene, μg/mL 

[Analyte], μg/mL

Your [Analyte], μg/mL 

Median [Analyte], μg/mL 

Apparent Precision, SD 

326331338339340341344 

Apparent Precision, SD 

Long-term Precision, SD 

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

1st Quartile (25%) Expectation 

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

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

Serum History Comments 

#339 Fresh frozen: 60:#326, 61:#331, 62:#338 Native, single-source 

#340 Fresh frozen: New Native, multiple-source 

#341 Fresh frozen: New, from beginning of production Native, single-source 

#344 Same as #341, but from end of production run Native, single-source 

Concordance, SD 

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

Individualized Report Page 6 / 13 

D7
NIST, this RR

 

 Set 1 of 38 

Individualized RR LXIII Report: FSV-BA

trans-β-Carotene, μg/mL 

[Analyte], μg/mL

Your [Analyte], μg/mL 

Median [Analyte], μg/mL 

Apparent Precision, SD 

326331338339340341344 

Apparent Precision, SD 

Long-term Precision, SD 

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

1st Quartile (25%) Expectation 

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

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

Serum History Comments 

#339 Fresh frozen: 60:#326, 61:#331, 62:#338 Native, single-source 

#340 Fresh frozen: New Native, multiple-source 

#341 Fresh frozen: New, from beginning of production Native, single-source 

#344 Same as #341, but from end of production run Native, single-source 

Concordance, SD 

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

Individualized Report Page 7 / 13 

D8
NIST, this RR

 

 Set 1 of 38 

Individualized RR LXIII Report: FSV-BA

Total α-Carotene, μg/mL 

[Analyte], μg/mL

Your [Analyte], μg/mL 

Median [Analyte], μg/mL 

Apparent Precision, SD 

326331338339340341344 

Apparent Precision, SD 

Long-term Precision, SD 

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

1st Quartile (25%) Expectation 

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

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

Serum History Comments 

#339 Fresh frozen: 60:#326, 61:#331, 62:#338 Native, single-source 

#340 Fresh frozen: New Native, multiple-source 

#341 Fresh frozen: New, from beginning of production Native, single-source 

#344 Same as #341, but from end of production run Native, single-source 

Concordance, SD 

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

Individualized Report Page 8 / 13 

D9
NIST, this RR

 

 Set 1 of 38 

Individualized RR LXIII Report: FSV-BA

Total Lycopene, μg/mL 

[Analyte], μg/mL

Your [Analyte], μg/mL 

Median [Analyte], μg/mL 

326331338339340341344 

Apparent Precision, SD 

Apparent Precision, SD 

Long-term Precision, SD 

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

1st Quartile (25%) Expectation 

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

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

Serum History Comments 

#339 Fresh frozen: 60:#326, 61:#331, 62:#338 Native, single-source 

#340 Fresh frozen: New Native, multiple-source 

#341 Fresh frozen: New, from beginning of production Native, single-source 

#344 Same as #341, but from end of production run Native, single-source 

Concordance, SD 

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

Individualized Report Page 9 / 13 

D10
NIST, this RR

 

 Set 1 of 38 

Individualized RR LXIII Report: FSV-BA

trans-Lycopene, μg/mL 

[Analyte], μg/mL

Your [Analyte], μg/mL 

Median [Analyte], μg/mL 

Apparent Precision, SD 

326331338339340341344 

Apparent Precision, SD 

Long-term Precision, SD 

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

1st Quartile (25%) Expectation 

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

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

Serum History Comments 

#339 Fresh frozen: 60:#326, 61:#331, 62:#338 Native, single-source 

#340 Fresh frozen: New Native, multiple-source 

#341 Fresh frozen: New, from beginning of production Native, single-source 

#344 Same as #341, but from end of production run Native, single-source 

Concordance, SD 

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

Individualized Report Page 10 / 13 

D11
NIST, this RR

 

 Set 1 of 38 

Individualized RR LXIII Report: FSV-BA

Total β-Cryptoxanthin, μg/mL 

[Analyte], μg/mL

Your [Analyte], μg/mL 

Median [Analyte], μg/mL 

Apparent Precision, SD 

326331338339340341344 

Apparent Precision, SD 

Long-term Precision, SD 

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

1st Quartile (25%) Expectation 

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

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

Serum History Comments 

#339 Fresh frozen: 60:#326, 61:#331, 62:#338 Native, single-source 

#340 Fresh frozen: New Native, multiple-source 

#341 Fresh frozen: New, from beginning of production Native, single-source 

#344 Same as #341, but from end of production run Native, single-source 

Concordance, SD 

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

Individualized Report Page 11 / 13 

D12
NIST, this RR

 

 Set 1 of 38 

Individualized RR LXIII Report: FSV-BA

Total Lutein&Zeaxanthin, μg/mL 

[Analyte], μg/mL

Your [Analyte], μg/mL 

Median [Analyte], μg/mL 

Apparent Precision, SD 

326331338339340341344 

Apparent Precision, SD 

Long-term Precision, SD 

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

1st Quartile (25%) Expectation 

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

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

Serum History Comments 

#339 Fresh frozen: 60:#326, 61:#331, 62:#338 Native, single-source 

#340 Fresh frozen: New Native, multiple-source 

#341 Fresh frozen: New, from beginning of production Native, single-source 

#344 Same as #341, but from end of production run Native, single-source 

Concordance, SD 

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

Individualized Report Page 12 / 13 

D13
 Set 1 of 38 

Individualized Round Robin LXIII Report: FSV-BA
 

Graphical Comparability Summary
 

Total Retinol α-Tocopherol Total β-Carotene 

D14

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 RR28 

The following five items were included in each package shipped to an RR28 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
November 5, 2007 

Dear Colleague: 

UNn'ED STATES DEPARTMENT OF COMMERCE 

National Institute of Standards and Technology 

Gaithersburg, Maryland 20899-

The samples within this package constitute Vitamin C Round Robin 28 (RR28) of the 2008 Micronutrients 

Measurement Quality Assurance Program. · 

' 

RR28 consists of four vials of frozen serum test samples (#26, #112, #116, and #119), one vial of frozen 

control serum (CS # 1) and one vial of ascorbic acid solid control material (Control) Please follow the 

attached protocols when you prepare and analyze these samples. If you cannot prepare the solid control 

solutions gravimetrically, please prepare equivalent solutions volumetrjcally 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.) · 

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

test samples. The target value and >=::95% confidence interval for target value and ::::95% confidence interval for 

CS #1 is 8.4 ±0.7 μmol/L of sample. 

Th~ report for RR27 will be mailed shortly. If you find your results for RR27 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. This SRM may be purchased from the Standard 

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

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

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

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

observe unusually large variation in replicate analyses. 

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

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

e-mail: jbthomas@nist.gov. 

We ask that you return your results for these RR28 samples before March 3, 2008. We would appreciate 

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

kept confidential. 

e 

alytical Chemistry Division 

Chemical Science and Technology Laboratory 

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

RR28 Report Form for Ascorbic Acid Solid Control Material Preparation 

RR28 Re.port Form for Control Material and Test Sample Analyses 

NlSI 

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 

CS #1 (see protocol below). The target values for this materials is 8.4 ±0.7 μmol/L of sample. 

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

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

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

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

measurement system may not be suitable for MPA-preserved samples. Please contact us: 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 material and test samples are in sealed ampoules. They were prepared by adding 

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

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

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

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

than 10 min otherwise some irreversible degradation may occur. 

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

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

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

E4
 

Participant #: Date: 

Vitamin C Round Robin 28 

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 3, 2008 

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 28 

NIST Micronutrient Measurement Quality Assurance Program
 

Analysis of Control Materials and Test Samples
 

Sample Replicate 1 Replicate 2 Units
 

Dilute Solution 1 μmol/L of Dilute Solution 

Dilute Solution 2 μmol/L of Dilute Solution 

Dilute Solution 3 μmol/L of Dilute Solution 

5% MPA Diluent μmol/L of Diluent 

μmol/L of Sample CS #1 

Target: 8.4 ±0.7 μmol/L 

Serum Test Sample #26 μmol/L of Sample 

Serum Test Sample #112 μmol/L of Sample 

Serum Test Sample #116 μmol/L of Sample 

Serum Test Sample #119 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 3, 2008
	

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 28
 

NIST Micronutrients Measurement Quality Assurance Program
 

Packing List and Shipment Receipt Confirmation Form
 

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

Label Form
 

VitC #26 Liquid frozen (1:1 serum:10% MPA) 

VitC #112 Liquid frozen (1:1 serum:10% MPA) 

VitC #116 Liquid frozen (1:1 serum:10% MPA) 

VitC #119 Liquid frozen (1:1 serum:10% MPA) 

CS #1 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 RR28 

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 2, 2008 

Dear Colleague: 

UNITED STATES DEPARTMENT OF COMMERCE 

National Institute of Standards and Technology 

Gaithersburg, Maryland 20899-

Enclosed is the summary report of the results for Round Robin 28 (RR 28) for the measurement 

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

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

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

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

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

1 OOxMADe/median. 

RR 28 consisted of four test samples (#26, #112, #116, and #119), one serum control material 

(CS # 1 ), and one solid control material for preparation of TAA control solutions. Details 

regarding the samples can be found in the enclosed repo1i. 

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

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 (RR 29) of the 2007 M2

QAP will be shipped 

during the week of May 19, 2008. 

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

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

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

in erely, \, 

. ea ce Brown Thomas 

search Chemist 

Analytical Chemistry Division 

Chemical Science and Technology Laboratory 

Enclosures 

Cc: L. C. Sander 

D.L. Duewer 

F2

NlSI 
The NIST M2

QAP Vitamin C Round Robin 28 (RR28) report consists of 

Page “Individualized” Report 

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

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

samples. 

2 Graphical summary of your RR28 sample measurements. 

Page “All Lab” Report 

1 A tabulation of results and summary statistics for Total Ascorbic Acid [TAA] in the RR28 

samples and control/calibration solutions. 

Serum-based Samples. One serum control and four unknowns were distributed in RR28. 

CS#1 SRM 970 level 1, ampouled in mid-1998. 

S28:1 VitC #26, ampouled in late 2001, previously distributed as sample S17:1 (RR17, Fall 02), 

S19:2 (RR19, Fall 03), S21:2 (RR21, Fall 04), S22:1 (RR24, Spring 05), and S24:1 (RR24, 

Spring 06). 

S28:2 VitC #112, ampouled in 1993, previously distributed as sample 179B=S04:2 (RR4, 1993) 

and S26:3 (RR26, Spring 07). 

S28:3 VitC #116, ampouled in 1995, previously distributed sample 682a=S08:3 (RR8, 1996), 

682a=S10:2 (RR10, 1997), and S25:4 (RR25, Fall 06). 

S28:4 VitC #119, ampouled in 1995, previously distributed sample 688b=S07:2 (RR7, Spring 

1995), 688b=S08:2 (RR8, 1997), and S24:4 (RR24, Spring 06). 

Results. 

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

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

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

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

dL/g·cm). 

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

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

are linear (R2

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

-1.1 to 2.1 and slopes range from 0.90 to 1.09). 

3)	 The Measured = p+q*Median regression parameters for samples S28:1 to S28:4 (columns 23 to 26 of 

the All Lab Report) mostly confirm the linearity of the measurement systems (R2

 close to 1 and RMS 

close to 0.0). There seems to be no strong relationship between the intercepts and slopes for the 

calibration solutions and for the regression-on-median for the unknown samples (see Figure 1). This 

implies that the performance of some measurement systems for [TAA] in 5% MPA:serum is different 

than it is in just 5% MPA – and that there may well be several causes for these differences. 

4)	 The median and the MADe for Vit C #112 (S28:2), #116 (S28:3) and 119 (S28:4), all ampouled 

more than 10 years ago, are effectively unchanged from their initial values. The median [TAA] value 

for VitC #26 (S28:1) is somewhat lower than all previous estimates for this material; it is possible 

that the [TAA] level in the relatively new material has declined. Since sample #26 has a very low 

F3
 

-1 

0 

1 

2 

Regression-on-Median Intercept, μmol/L 

[TAA] level, it is plausible that it could be less stable than materials with higher [TAA]. It is also 

plausible that measurements of low [TAA] levels are more susceptible to measurement system 

limitations (see above) than are the higher levels. 

Comparison of the sample #26 measurements with those of the relatively low-[TAA] level control 

material CS#1 (see Figure 2) suggests measurement sensitivity is at least a contributing factor: 

participants with the lowest values for sample #26 also reported low values for the control. Since the 

measurement variability of sample #26 measurements does not appear to have increased with time, if 

the material has degraded then it degraded to about the same extent in all ampoules of the material. 

We will continue distribute this material in future studies. 

Figure 1: Comparison of Intercepts and Slopes
 

Between Gravimetric Calibration (Measured = a+b*Participant Gravimetric)and
 

Regression-on-Median (Measured = p+q*Interlaboratory Median) Models
 Regression-on-Median Slope 

1.10 

1.05 

1.00 

0.95 

0.90 

-2 0.85 

-2	 -1 0 1 2 0.85 0.90 0.95 1.00 1.05 1.10 

Gravimetric Calibration Intercept, μmol/L Gravimetric Calibration Slope 

Figure 2: Comparison of Measured [TAA] in CS #1 and Vit C #26 = S28:1 

13 

[TAA] in S28:1, μmol/L 

11 

9 

7 

5 

3 

3 5 7 9 11 13 

[TAA] in CS#1, μmol/L 

F4
Appendix G. “All-Lab Report” for RR28 

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

two exceptions: 

• the participant identifiers (Lab) have been altered. 

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

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

identification codes assigned to laboratories. 

G1
Micronutrients Measurement Quality Assurance Program for Total Ascorbic Acid
 

"Round Robin" 28 - March 2008
 

Control / Calibration Samples MPA Dilute Solution 1 

Measured, μmol/L Measured = a + b*Grav 

Density Spectrophotometry Grav, μmol/L Measured, μmol/L 

Lab Date Dil:1 Dil:2 Dil:3 Dil:1 Dil:2 Dil:3 MPA Inter Slope R2 RMS g/mL CS#1 S28:1 S28:2 S28:3 

λmax Amax E1% 

VC-MA 04/03/08 57.8 28.9 14.4 59.6 31.5 15.8 0.0 0.69 1.03 0.999 1.0 1.035 243. 0.5720 562.2 9.0 10.4 75.0 45.0 

VC-MB 15/11/07 57.2 28.4 14.1 56.8 27.4 13.7 0.0 -0.31 0.99 1.000 0.5 1.030 243. 0.5710 567.1 5.9 7.7 65.0 42.1 

VC-MC 05/12/07 54.9 27.5 14.3 55.3 26.3 14.2 0.0 -0.37 1.01 0.999 0.8 1.031 243. 0.5220 539.4 9.3 9.3 70.9 44.1 

VC-ME 29/02/08 57.5 28.8 14.4 57.0 29.2 15.0 0.0 0.44 0.99 1.000 0.5 1.030 244. 0.5234 516.7 8.7 9.1 68.6 42.8 

VC-MG 05/02/08 61.6 31.5 17.3 63.1 31.5 19.4 0.0 0.48 1.02 0.999 1.2 1.028 243.4 0.6200 571.9 9.7 9.1 70.2 47.2 

VC-MH 13/02/08 61.1 30.6 15.1 60.8 30.8 15.0 0.0 0.04 1.00 1.000 0.2 1.031 243.6 0.5985 555.9 8.4 9.1 65.0 41.6 

VC-MI 07/02/08 56.4 25.2 14.1 61.1 25.7 13.3 0.0 -1.14 1.09 0.999 1.2 1.029 8.1 7.7 64.6 43.6 

VC-MJ 03/03/08 58.1 28.5 14.8 60.5 28.3 14.8 0.3 -0.34 1.04 0.999 0.9 1.027 10.4 13.6 74.9 42.0 

254 a 0.367 a 358.6 a 

VC-MK 03/01/08 57.6 29.0 14.2 53.5 27.9 16.2 1.2 2.12 0.90 0.998 1.1 1.033 244. 0.5722 564.5 7.8 11.9 80.2 41.0 

VC-MN 04/03/08 60.8 31.0 15.7 61.2 30.6 18.7 0.0 1.05 0.99 0.997 1.8 1.026 243.4 0.6369 595.1 8.1 8.8 69.4 40.1 

VC-MP 06/03/08 nd 6.0 69.3 42.6 

VC-MU 07/02/08 6.2 3.7 62.2 37.8 

VC-NF 27/02/08 59.6 29.4 15.1 59.3 30.0 15.1 0.0 0.18 1.00 1.000 0.5 1.034 243. 0.5860 558.5 7.9 7.9 59.1 38.7 

G2

N 11 11 11 11 11 11 11 

58.4 29.0 14.9 58.9 29.0 15.5 0.1 

2.1 1.7 0.9 2.9 2.0 1.9 0.4 

N 11 9 9 9 12 13 13 13 

Average Average 1.030 243.4 0.5780 559.0 8.3 8.8 68.8 42.2 

SD SD 0.003 0.4 0.0387 21.7 1.3 2.5 5.8 2.5 

Min 54.9 25.16 14.1 

57.3 28.46 14.3 

57.8 28.89 14.4 

60.2 29.98 15.1 

61.6 31.47 17.3 

2.1 0.7 0.5 

4 2 4 

53.5 25.70 13.3 0.0 

56.9 27.63 14.5 0.0 

59.6 29.24 15.0 0.0 

60.9 30.69 16.0 0.0 

63.1 31.50 19.4 1.2 

2.4 2.2 1.2 0.0 

4 8 8 

Min 1.026 243.0 0.5220 516.7 5.9 3.7 59.1 37.8 

%25 %25 1.029 243.0 0.5710 555.9 7.8 7.7 65.0 41.0 

Median Median 1.030 243.4 0.5722 562.2 8.2 9.1 69.3 42.1 

%75 %75 1.032 243.6 0.5985 567.1 9.1 9.3 70.9 43.6 

Max Max 1.035 244.0 0.6369 595.1 10.4 13.6 80.2 47.2 

MADe eSD 0.0 0.6 0.0390 9.3 1.0 1.9 6.4 2.2 

CV CV 0.27 0.24 6.8 1.7 12 21 9 5 

a) 5% Trichloroacetic acid solution 

All Lab Report 
Appendix H. Representative “Individualized Report” for RR28 

Each participant in RR28 received an “Individualized Report” reflecting their reported 

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

“VC-MA”. 

H1
 

Set 1 of 13 

Vitamin C "Round Robin" 28 Report: Participant VC-MA
 

MPA Dilute Solution 1 Control/Calibration Solutions 

Density Spectrophotometry Ymeas = Inter + Slope* Xgrav 

Date RR Method 

10/17/05 23 HPLC-EC 

03/09/06 24 HPLC-EC 

08/28/06 25 HPLC-EC 

03/20/07 26 HPLC-EC 

10/05/07 27 HPLC-EC 

03/04/08 28 HPLC-EC 

g/mL 

1.030 

1.031 

1.039 

1.033 

1.032 

1.035 

λmax Amax E1% 

244.0 0.562 567.9 

244.0 0.568 586.7 

242.0 0.555 557.4 

244.0 0.573 554.3 

242.0 0.561 557.2 

243.0 0.572 562.2 

Inter Slope R2 SEE 

-0.6 1.09 0.998 1.47 

0.2 1.13 1.000 0.41 

0.8 0.95 0.999 0.92 

0.3 1.00 1.000 0.31 

-0.1 0.99 1.000 0.14 

0.7 1.03 0.999 0.99 

Mean 1.034 243.2 0.57 564.3 0.71 

SD 0.003 1.0 0.01 12.0 0.50 

CV 0.32 0.40 1.3 2.1 

[TAA] mmol/Lsample 

6 9.5 0.2 0.6 

3 73.1 0.5 7.8 

3 42.5 0.5 2.3 

Date RR Sample 

10/17/05 23 CS#1 

03/09/06 24 CS#1 

08/28/06 25 CS#1 

03/20/07 26 CS#1 

03/04/08 28 CS#1 

12/12/02 17 S17:1 

11/13/03 19 S19:2 

09/13/04 21 S21:2 

03/08/05 22 S22:1 

03/09/06 24 S24:1 

03/04/08 28 S28:1 

09/16/93 04 S04:2 

03/20/07 26 S26:3 

03/04/08 28 S28:2 

ND 08 

08/20/97 10 S10:2 

08/28/06 25 S25:4 

03/04/08 28 S28:3 

05/23/95 07 S07:2 

Rep1 Rep2 Fadj Mean SDdup 

9.3 9.5 1.0 9.4 0.1 

9.3 9.2 1.0 9.3 0.0 

8.3 8.6 1.0 8.4 0.2 

8.6 8.3 1.0 8.5 0.2 

9.1 9.0 1.0 9.0 0.1 

N Mean SDrepeat SDreprod 

5 8.9 0.1 0.5 

9.9 9.1 1.0 9.5 0.6 

9.2 9.1 1.0 9.2 0.1 

8.8 8.7 1.0 8.7 0.1 

9.6 9.6 1.0 9.6 0.0 

9.8 9.6 1.0 9.7 0.2 

10.4 10.3 1.0 10.4 0.1 

2.3 2.3 28.4 64.4 0.0 

79.7 79.8 1.0 79.8 0.1 

75.6 74.3 1.0 75.0 0.9 

81.5 80.6 0.5 40.5 0.3 

42.0 42.2 1.0 42.1 0.2 

45.6 44.4 1.0 45.0 0.9 

3 27.8 0.5 2.3 

ND 08 

03/09/06 24 S24:4 

03/04/08 28 S28:4 

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 

51.05 49.75 0.5 25.2 0.5 

29.0 29.5 1.0 29.2 0.4 

29.5 28.7 1.0 29.1 0.5 

Individualized Report Page 1 / 2 

H2
 

 

 

NIST, RR 22

Set 1 of 13 

Vitamin C "Round Robin" 28 Report: Participant VC-MA 

Total Ascorbic Acid 

[Total Ascorbic Acid], μmol/L 

Your [Total Ascorbic Acid], μmol/L

S17:1S19:2S21:2S22:1S24:1S28:1

Apparent Precision, SD S04:2

S26:3S28:2S08:3S10:2S25:4S28:3S07:2S08:1S24:4S28:4 

Median [Total Ascorbic Acid], μmol/L 

Concordance, SD 

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

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

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

Sample Comments 

S28:1 VitC #26, previously distributed in RRs 17 (Sep-02), 19 (Sep-03), 21 (Sep-04), 22 (Mar-05), 24 (Mar-06) 

S28:2 VitC #112, previously distributed in RRs 4 (Sep-93), 26 (Mar-07) 

S28:3 VitC #116, previously distributed in RRs 8 (Sep-95), 10 (Jan-97), 25 (Sep-06) 

S28:4 VitC #119, previously distributed in RRs 7 (Jun-95), 8 (Sep-95), 24 (Mar-06) 

Individualized Report Page 2 / 2 

H3