NISTIR 7880-43 

NIST Micronutrients Measurement

Quality Assurance Program

Winter 2014 

Comparability Studies

Results for Round Robin LXXV 

Fat-Soluble Vitamins and Carotenoids in Human Serum 

and Round Robin 40 Ascorbic Acid in Human Serum

David L. Duewer

Jeanice B. Thomas

http://dx.doi.org/10.6028/NIST.IR.7880-43

195214244328347402357365375389398403359363373379400405404406

[Total Retinol], μg/mL

FSV RR LXXV

RR11RR12RR13RR14RR15RR18RR20RR22RR25RR29RR36RR37RR39RR40

S32:2S33:4S35:2S38:2S40:3S34:4S36:1S36:4S38:4S40:4

[Total Ascorbic Acid], μmol/L

VC RR 40
NISTIR 7880-43

NIST Micronutrients Measurement

Quality Assurance Program

Winter 2014 

Comparability Studies

Results for Round Robin LXXV 

Fat-Soluble Vitamins and Carotenoids in Human Serum

and Round Robin 40 Ascorbic Acid in Human Serum

David L. Duewer

Jeanice B. Thomas

Chemical Sciences Division

Materials Measurement Laboratory 

http://dx.doi.org/10.6028/NIST.IR.7880-43 

June 2015 

U.S. Department of Commerce 

Penny Pritzker, Secretary

National Institute of Standards and Technology 

Willie E. May, 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 2014 MMQAP measurement comparability improvement studies: 1) Round Robin LXXV

Fat-Soluble Vitamins and Carotenoids in Human Serum and 2) Round Robin 40 Total Ascorbic Acid 

in Human Serum. The materials for both studies were shipped to participants in January 2014. To 

help reduce overhead costs and avoid raising participation fees, the materials for Round Robin 

LXXVI Fat-Soluble Vitamins and Carotenoids in Human Serum and Round Robin 41 Total 

Ascorbic Acid in Human Serum were also shipped in the same shipping container. Participants in 

Round Robins LXXV and 41 were requested to provide measurement results by April 18, 2014. 

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

Round Robin 40: Vitamin C in Human Serum ............................................................................... 2

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

Appendix A. Shipping Package Inserts for RR75 ........................................................................ A1

Appendix B. Final Report for RR75 .............................................................................................. B1 

Appendix C. All-Lab Report for RR75 .......................................................................................... C1

Appendix D. Representative Individualized Report for RR75 ................................................... D1

Appendix E. Shipping Package Inserts for RR40 ......................................................................... E1

Appendix F. Final Report for RR40 ............................................................................................... F1

Appendix G. “All-Lab Report” for RR40..................................................................................... G1

Appendix H. Representative “Individualized Report” for RR40 ............................................... 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 LXXV: Fat-Soluble Vitamins and Carotenoids in Human Serum

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

LXXV comparability study (hereafter referred to as RR75) 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 

January 2014 in the same shipping package as the Round Robin LXXVI (RR76) samples but in a 

separately labeled plastic bag. Participants were requested to provide measurement results by April 

18, 2014. 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 RR75 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 

1 
numerical “score card” for each participant’s measurement comparability for the more 

commonly reported analytes. This All-Lab Report is reproduced as Appendix C. 

• 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 the Individualized Report 

are described in detail elsewhere [3]. An example Individualized Report is reproduced as 

Appendix D. 

Round Robin 40: Vitamin C in Human Serum

Participants in the MMQAP Vitamin C in Human Serum Round Robin 40 comparability study 

(hereafter referred to as RR40) received four frozen serum test samples and two frozen control sera. 

Unless multiple vials were previously requested, participants received one vial of each material. 

These materials were shipped on dry ice to participants in January 2014 in the same shipping 

package as the Round Robin 41 (RR41) samples but in a separately labeled plastic bag. Participants 

were requested to provide measurement results by April 18, 2014. 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). 

The final report delivered to every participant in RR40 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 All-Lab 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 the Individualized 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 RR75 

The following three items were included in each package shipped to an RR75 participant:

• Cover letter

• Datasheet

• Packing List and Shipment Receipt Confirmation Form 

The RR75 samples were backed in a sealed waterproof bag and labeled: 

A cover letter describing both RR75 and RR76, datasheets for both studies, and packing 

lists for both studies were enclosed in a sealed waterproof bag placed at the top of the 

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

NIST MMQAP-FSV: RR LXXV

Micronutrients Measurement Fat-Soluble 

Vitamin

Quality Assurance Program

Winter 2014 Samples 

Results due on or before:

April 18, 2014

A1 
February 10, 2014 

Dear Colleague: 

UNITED STATES DEPARTMENT OF COMMERCE 

National Institute of Standards and Technology 

Gaithersburg, Maryland 20899-

Enclosed are samples for the fat-soluble vitamins and carotenoids in serum studies for the 2014 NIST 

Micronutrients Measurement Quality Assurance Program. Sample details are provided below. 

Comparability study/Round Robin (RR) 

RR75 

RR76 

Sample description 

Sera 402 - 406 

Sera 407 - 411 

Results due 

April 18, 2014 

September 15, 2014 

The package for each study consists of one vial of lyophilized serum and one vial each of four liquidfrozen serum samples for analysis along with a form for reporting your resu,lts .. Jhe~e .smr.iples sh~u!d. be 

stored in the dark at or below -20 °C upon receipt. When reporting your results, pleas~ sh~_mit' on.~ yal~e 

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

indicate this result on the form as "nq" (Not Quantified) or "<x" where x is your established limit of 

quantification. Results are due to NIST for each studi as indicated above. Results received more than 

two weeks after the due date may not be included in the summary report for the study. The feedback 

report concerning each study will be distributed in May and October 2014, respectively. Please contact us 

immediately if this schedule is problematic for your laboratory. 

Samples should be allowed to stand at room temperature under subdued light until thawed. Add 1.00 mL 

reagent-grade water to the lyophilized serum. We recommend that sample mixing be facilitated with 3 to 

5 min agitation in an ultrasonic bath or at least 15 min at room temperature with intermittent swirling. 

(CAUTION: Vigorous shaking wili cause foaming and possibly interfere with accurate measurement. 

The rubber stopper contains phthalate esters that may leach into the sample upon intermittent contact of 

the liquid sample with the stopper. These esters absorb strongly in the UV region and elute near retinal in 

most LC systems creating analytical problems). Water should not be added to the liquid-frozen 

samples. 

For consistency, we request that laboratodes use the following f;lbsqrptivities (dL/g ·cm}:, retinpl; 1843 at 

325 nm (ethanol); retinyl palmitate, 975 at325 nm (ethanol); a-tocopherol, 75;8 at292 nm (ethanol); ytocopherol, 91.4 at 298 nm (ethanol); a-carotene, 2800 at 444 nm (hexane); ~~carotene, 2560 at 450 nm 

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

Please rep011 your results by e-mail to david.duewer@nist.gov or fax to 301-977-0685. If you have 

questions or comments regarding the studies, please contact us at 301-975-3120 (Jeanice); 

jbthomas@nist.gov or 301-975-3935 (Dave); david.duewer@nist.gov. 

nice B. Thoma, M.B.A. 

esearch Chemist 

Chemical Sciences Division 

Material Measurement Laboratory 

Enclosures 

~\/~ David 

Research 

L. Duewer, 

Chembmetrician 

~ Chemical Sciences Division 

Material MeasurementLaboratory 

A2
Participant #: ________ Date: _____________

Mail: M2QAP

 NIST, Stop 8392

 Gaithersburg, MD 20899-8392

Please return results by

18-April-2014 Fax: 301-977-0685

Email: David.Duewer@NIST.gov

Analyte 402 403 404 405 406 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

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

Phytoene

Phytofluene

* we prefer μg/mL

Were the samples frozen when received? Yes | No

Comments:

Round Robin LXXV: Human Sera

NIST Micronutrients Measurement Quality Assurance Program

A3
Participant #: ________ Date: _____________

Mail: M2QAP

 NIST, Stop 8392

 Gaithersburg, MD 20899-8392

Fax: 301-977-0685

Email: David.Duewer@NIST.gov

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

Serum Form Reconstitute? Vial/Cap

#402 Lyophilized Yes 5 mL clear / silver

#403 Liquid frozen No 3 mL amber / red

#404 Liquid frozen No 2 mL clear / green

#405 Liquid frozen No 2 mL amber / green

#406 Liquid frozen No 3 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) Email (david.duewer@nist.gov) or fax (301-977-0685) us the

following information:

1) Date this shipment arrived: ___________________________

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

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

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

4) Did the 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

Packing List and Shipment Receipt Confirmation Form

NIST Micronutrients Measurement Quality Assurance Program

Fat-Soluble Vitamins Round Robin LXXV

A4
Appendix B. Final Report for RR75 

The following four pages are the final report for RR75 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 13, 2014 

Dear Colleague:

Enclosed is the summary report of the results for “Round Robin” LXXV (RR75) of the 2014 NIST 

Micronutrients Measurement Quality Assurance Program (MMQAP) 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. RR75 (Sera 402 - 406) consisted of one vial of 

lyophilized serum and one vial each of four liquid-frozen serum samples. Details regarding the samples 

can be found in the enclosed report.

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

Lab Report. Combined results rated 1 to 3 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.

We are pleased that MMQAP participant Professor Garry Duthie of the Rowett Institute of Nutrition and 

Health, University of Aberdeen, Scotland is providing the (free) on-line recipe book Stovies Reloaded: 

Traditional Scottish Recipes Made Healthier at http://www.abdn.ac.uk/rowett/policy-industry/stovies.php. 

Prof. Duthie states that “Stovies Reloaded” is our light-hearted take on traditional Scottish recipes and 

how they can be adapted in the light of increased nutritional knowledge. ... We hope that this book may 

play a small part in encouraging people to rediscover cooking skills, take an interest in traditional 

Scottish fare and eat a more healthy diet.” This website also provides links to a wealth of other 

information developed at the Rowett Institute relating to nutrition, food safety, and human health.

The results for fat-soluble vitamins and carotenoids in serum RRLXXVI and vitamin C in serum RR41 

are due on or before September 15, 2014. We will send you a reminder in August. If you have questions 

or concerns regarding this report, please contact David Duewer at 301-975-3935; e-mail: 

david.duewer@nist.gov or me at 301-975-3120; e-mail: jbthomas@nist.gov; or fax: 301-977-0685. 

Sincerely,

Jeanice Brown Thomas, M.B.A. David L. Duewer, Ph.D. 

Research Chemist Research Chemometrician 

Chemical Sciences Division Chemical Sciences Division

Material Measurement Laboratory Material Measurement Laboratory 

Enclosures 

Cc: L.C. Sander 

UNITED STATES DEPARTMENT OF COMMERCE

National Institute of Standards and Technology

Gaithersburg, Maryland 20899-8390

B2
The NIST MMQAP Round Robin LXXV (RR75) report consists of: 

Page All-Lab Report

1-4 A listing of all results and statistics for analytes reported by more than one participant.

5 The legend for the list of results and statistics.

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

Page Individualized Report

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

2 to 

n

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

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

n+1 The graphical Comparability Summary (target plot) of measurement performance.

Samples. Five samples were distributed to each participant in RR75. 

Serum Description Prior Distributions

402 Lyophilized, augmented, multi-donor, prepared in 1994. 

This material is a 1:1 blend of stripped serum and a 

serum pool augmented with retinol, retinyl palmitate, 

and α-tocopherol. 

#195:RR31-6/94, #214:RR35-9/95;

#244:RR43-6/98, #328:RR60-9/06;

#347:RR64-9/08 

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

This is Level I of SRM 968e.

#357:RR66-9/09, #365:RR67-3/10, 

#376:RR69-3/11, #389:RR72-9/12 

404 Fresh-frozen, augmented, single donor, prepared in 

2013. This material was prepared from the same 

(reasonably) normal serum as #406 but was augmented 

with trans-retinol, retinyl palmitate, and β-tocopherol, 

First MMQAP distribution

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

This is Level III of SRM 968e. 

#359:RR66-9/09, #363:RR67-3/10,

#373:RR69-3/11, #379:RR70-9/11 

406 Fresh-frozen, augmented, single donor, prepared in 

2013. This material was prepared from the same 

(reasonably) normal serum as #404 but was augmented 

with cis-retinol and γ-tocopherol. 

First MMQAP distribution

Results

1) Stability: There have been no significant changes in either the level nor the variability in any of the

analytes in the 20-year old lyophilized Serum 402 nor in the five-year old fresh-frozen SRM 968e 

materials, Sera 403 and 405. 

2) γ/β-Tocopherol: A year or two ago, we were asked why we designate as “γ/β-tocopherol” what most

literature reports as “γ-tocopherol.” While in our experience reliably separating γ from β requires

specialized methods, it had been some years since we last investigated tocopherol separations and

agreed that it was quite possible that some of you may have developed methods that resolved these

two isomers. The Sera {404,406} pair was produced in part to test this. The native γ/β concentration

Summary Report B3 1 / 3 
in the serum used to prepare the pair was about 1.1 μg/mL. Serum 404 was spiked with β-tocopherol 

and Serum 406 was spiked with γ-tocopherol, both to have high-normal levels of about 4 μg/mL.

Figure 1 compares the reported values for γ/β-tocopherol in Serum 404 to those in Serum 406, with 

each solid circle representing the values reported by one participant. The solid red box represents the 

native γ/β content of the original serum; the red line represents the expected ratio of the two spikes. 

Scatter along the red line represents calibration issues that affect both samples proportionally. Scatter 

perpendicular to the red line combines measurement imprecision with potential bias due to the nature 

of the spikes. The relative absence of perpendicular scatter strongly suggests that all participants 

measure the same “γ/β-tocopherol” measurand regardless of whether “γ/β” is mostly γ or mostly β. 

Further, there were no reported comments on the chromatographic shape of the γ/β-tocopherol peak in 

either serum. We conclude that all participants are indeed measuring “γ/β-tocopherol.” 

Figure 1: Comparison of Reported Values of γ/β-Tocopherol in Sera 404 and 406 

3) cis-/trans-Retinol: The Sera {404,406} pair was also designed to evaluate measurement systems that

report “total retinol” or “trans-retinol.” The total retinol concentration in the serum used to prepare

the pair was about 0.42 μg/mL. Serum 404 was spiked with all-trans-retinol to have a very high level

of about 1.1 μg/mL and Serum 406 was spiked with a smaller quantity of 13-cis-retinol to have a

fairly normal total retinol level of about 0.6 μg/mL.

Figure 2 compares the reported values for total retinol in Serum 406 to those in Serum 404. As

above, the solid red box represents the native total content of the original serum, the red line

represents the expected ratio of the two spikes, scatter along the red line represents calibration issues

that affect both samples proportionally, and scatter perpendicular to the red line combines

measurement imprecision with potential bias due to the nature of the spikes. In contrast to

“γ/β-tocopherol”, several participants reported total retinol values for Serum 406 that apparently

exclude the contribution from the 13-cis spike.

1

2

3

4

5

1 2 3 4 5 6

Serum 404: γ/β-tocopherol, μg/mL

Serum 406: γ/β-tocopherol, μg/mL

Spiked with γ-Tocopherol

Spiked with β-Tocopherol

Summary Report B4 2 / 3 
Figure 2: Comparison of Reported values of Total Retinol in Sera 404 and 406 

Indeed, the open circles in Figure 2 represent results reported by participants who resolved the two 

isomers. Figure 3 presents the relevant sections of their chromatograms for Sera 404 and 406. The 

peak for 13-cis-retinol elutes somewhat earlier than does all-trans-retinol in both methods. 

Partially resolved Completely resolved

Figure 3: Chromatograms of Retinol in Sera 404 and Serum 406 

Given the evidence of a somewhat variable definition of “total retinol” among the participants, we 

strongly encourage all of you to examine the retinol sections of your chromatograms for Sera 404 and 

406. If you are resolving the 13-cis but not including it in the total integration, you may want to 

either report trans-retinol or modify your method. If you are not resolving the 13-cis peak but report 

trans-retinol, you may want to report total retinol or modify your method. 

0.4

0.5

0.6

0.7

0.4 0.6 0.8 1.0 1.2 1.4

Serum 406: Total Retinol, μg/mL

Serum 404: Total Retinol, μg/mL

Spiked with all-trans-Retinol

Spiked with 13-cis-Retinol

Serum 404

Serum 406 Serum 406

Serum 404

Summary Report B5 3 / 3 
Appendix C. “All-Lab Report” for RR75 

The following six pages are the “All-Lab Report” for RR75 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. 

C1 
Round Robin LXXV Laboratory Results

All Lab Report 

Lab 402 403 404 405 406 402 403 404 405 406 402 403 404 405 406 402 403 404 405 40

FSV-BB 0.394 0.370 1.16 0.657 0.637 0.080 0.007 0.43 0.087 0.026 7.24 7.03 8.99 18.2 8.9

FSV-BC 0.354 0.318 1.08 0.630 0.451

FSV-BD 0.421 0.414 1.52 0.762 0.675 8.20 7.20 8.90 20.6 8.7

FSV-BE 0.303 0.285 0.93 0.520 0.466 6.44 5.93 7.68 17.6 7.7

FSV-BF 0.390 0.360 1.17 0.680 0.640 6.50 6.30 7.50 17.4 7.5

FSV-BFa 0.420 0.400 1.32 0.730 0.660 7.40 7.30 9.10 20.5 9.2

FSV-BG 0.420 0.357 1.20 0.651 0.631 0.088 0.016 0.59 0.107 0.022 6.66 6.35 8.57 19.4 8.5

FSV-BH 0.282 0.321 1.05 0.589 0.477 6.31 5.81 7.75 17.0 7.6

FSV-BJ 0.376 0.325 1.28 0.662 0.633 7.51 6.51 8.29 19.6 8.4

FSV-BK 0.369 0.343 1.07 0.619 0.595 6.65 6.47 8.03 18.7 8.1

FSV-BL 0.400 0.370 1.15 0.660 0.600 6.50 6.50 7.80 16.8 7.8

FSV-BM 0.340 0.260 1.02 0.580 0.610 7.30 5.10 8.40 17.2 8.3

FSV-BN 0.426 0.365 1.25 0.687 0.639 6.55 5.79 7.11 17.0 6.9

FSV-BO 0.360 0.370 1.15 0.680 0.630 7.19 6.76 8.10 19.2 8.4

FSV-BR ≥0.300 ≥0.370 ≥1.120 ≥0.650 ≥0.640 0.300 0.370 1.120 0.650 0.640 7.60 6.50 7.90 18.8 7.3

FSV-BS 0.422 0.346 1.18 0.661 0.661

FSV-BT 0.428 0.361 0.97 0.608 0.567 6.90 6.80 7.81 18.8 8.1

FSV-BU 0.207 0.340 1.15 0.650 0.520 6.99 6.66 8.41 19.2 8.7

FSV-BV 0.298 0.360 1.13 0.581 0.543 6.95 6.86 8.35 16.9 8.7

FSV-BW 0.510 0.590 1.35 0.820 0.700 0.228 0.011 1.00 0.197 0.048 6.20 6.25 7.30 17.6 7.1

FSV-CD 0.350 0.316 1.00 0.660 0.552 nq nq 0.51 nq nq 6.82 6.45 7.91 18.3 8.1

FSV-CE 0.357 0.329 1.04 0.637 0.538 5.53 7.95 8.43 21.7 8.9

FSV-CG 0.431 0.399 1.13 0.670 0.627 7.08 6.83 8.27 18.8 8.3

FSV-CI 0.418 0.402 1.30 0.726 0.696 0.119 0.017 0.54 0.110 0.027 8.00 7.28 8.90 20.2 9.0

FSV-CO 6.16 6.25 7.68 18.5 8.0

FSV-CZ 0.395 0.431 1.32 0.696 0.708 6.92 7.04 8.89 17.3 8.8

FSV-DD 0.320 0.300 0.91 0.530 0.510

FSV-DV 0.360 0.358 1.14 0.673 0.601 7.60 7.20 8.60 18.0 9.4

FSV-EE

FSV-EZ 0.391 0.346 1.16 0.672 0.549 0.104 <0.02 0.55 0.073 <0.02 6.74 6.53 8.22 19.3 7.9

FSV-FK 0.401 0.335 1.06 0.611 0.626 7.30 6.30 8.20 17.6 8.0

FSV-FZ ≥0.386 ≥0.346 ≥1.129 ≥0.637 ≥0.451 0.386 0.346 1.129 0.637 0.451 0.063 0.012 0.25 0.081 0.017 7.48 6.63 8.58 18.9 8.1

FSV-GD 0.341 0.344 1.03 0.613 0.613 6.79 6.61 8.11 18.6 8.1

N 29 29 29 29 29 2 2 2 2 2 6 5 7 6 5 29 29 29 29 2

Min 0.207 0.260 0.91 0.520 0.451 0.300 0.346 1.120 0.637 0.451 0.063 0.007 0.25 0.073 0.017 5.53 5.10 7.11 16.8 6.9

Median 0.390 0.357 1.15 0.660 0.613 0.343 0.358 1.125 0.644 0.546 0.096 0.012 0.54 0.097 0.026 6.92 6.53 8.22 18.6 8.1

Max 0.510 0.590 1.52 0.820 0.708 0.386 0.370 1.129 0.650 0.640 0.228 0.017 1.00 0.197 0.048 8.20 7.95 9.10 21.7 9.4

eSD 0.048 0.033 0.14 0.045 0.070 0.029 0.006 0.08 0.021 0.006 0.56 0.41 0.53 1.5 0.6

eCV 12 9 13 7 11 30 46 15 22 23 8 6 6 8 

Npast 39 30 0 31 0 8 8 0 8 0 10 7 0 9 0 40 30 0 31 

Medianpast 0.378 0.356 0.650 0.429 0.347 0.618 0.115 0.011 0.094 7.04 6.79 18.7 

SDpast 0.040 0.028 0.053 0.055 0.035 0.087 0.031 0.004 0.025 0.71 0.54 1.4 

NAV 0.390 0.357 1.15 0.660 0.613 0.096 0.012 0.54 0.097 0.026 6.92 6.53 8.22 18.6 8.1

NAU 0.048 0.033 0.14 0.052 0.070 0.029 0.011 0.12 0.026 0.012 0.58 0.56 0.66 1.5 0.6

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

C2
Round Robin LXXV Laboratory Results

All Lab Report 

Lab

FSV-BB

FSV-BC

FSV-BD

FSV-BE

FSV-BF

FSV-BFa

FSV-BG

FSV-BH

FSV-BJ

FSV-BK

FSV-BL

FSV-BM

FSV-BN

FSV-BO

FSV-BR

FSV-BS

FSV-BT

FSV-BU

FSV-BV

FSV-BW

FSV-CD

FSV-CE

FSV-CG

FSV-CI

FSV-CO

FSV-CZ

FSV-DD

FSV-DV

FSV-EE

FSV-EZ

FSV-FK

FSV-FZ

FSV-GD

N

Min

Median

Max

eSD

eCV

Npast

Medianpast

SDpast

NAV

NAU

402 403 404 405 406 402 403 404 405 406 402 403 404 405 406 402 403 404 405 40

0.078 0.094 0.129 0.202 0.136 0.314 0.082 0.415 0.371 0.399 0.286 0.079 0.378 0.338 0.367 0.028 0.003 0.037 0.033 0.0

0.276 0.080 0.348 0.395 0.345

0.481 0.083 0.318 0.399 0.382

0.276 0.086 0.366 0.405 0.344 

0.230 0.066 0.317 0.376 0.304 

0.390 0.086 0.464 0.574 0.522 

0.326 0.089 0.379 0.406 0.371 

0.339 0.082 0.363 0.336 0.374 

0.308 0.103 0.396 0.478 0.350

0.078 0.108 0.121 0.187 0.126 0.354 0.106 0.381 0.431 0.412 0.322 0.097 0.355 0.413 0.386 0.032 0.009 0.026 0.018 0.0

0.352 0.103 0.393 0.393 0.400 

0.351 0.101 0.449 0.428 0.443 

0.440 0.108 0.532 0.590 0.518 

0.315 0.094 0.395 0.420 0.420 

0.229 0.201 0.748 0.928 0.838

0.284 0.418 0.444 0.588 0.445 0.298 0.085 0.362 0.391 0.370 0.274 0.080 0.340 0.371 0.348 0.023 0.005 0.022 0.020 0.0

0.260 0.075 0.348 0.404 0.357 

0.235 0.095 0.380 0.398 0.374 

0.235 0.104 0.272 0.305 0.288

≥0.398 ≥0.070 ≥0.396 ≥0.300 ≥0.375 0.398 0.070 0.396 0.300 0.375

≥0.411 ≥0.090 ≥0.415 ≥0.393 ≥0.404 0.411 0.090 0.415 0.393 0.404

0.337 0.095 0.416 0.401 0.404

0.307 0.111 0.369 0.410 0.369 0.270 0.094 0.326 0.362 0.326 0.037 0.017 0.043 0.048 0.0

3 3 3 3 3 21 21 21 21 21 6 6 6 6 6 4 4 4 4 

0.078 0.094 0.121 0.187 0.126 0.229 0.066 0.272 0.305 0.288 0.270 0.070 0.326 0.300 0.326 0.023 0.003 0.022 0.018 0.0

0.078 0.108 0.129 0.202 0.136 0.314 0.094 0.380 0.404 0.374 0.304 0.085 0.367 0.367 0.371 0.030 0.007 0.031 0.027 0.0

0.284 0.418 0.444 0.588 0.445 0.481 0.201 0.748 0.928 0.838 0.411 0.097 0.415 0.413 0.404 0.037 0.017 0.043 0.048 0.0

0.057 0.015 0.047 0.024 0.043 0.048 0.011 0.042 0.041 0.028 0.007 0.005 0.011 0.011 0.0

18 16 12 6 11 16 13 11 11 8 22 68 35 43 

13 7 0 6 0 29 20 0 21 0 9 6 0 7 0 7 6 0 7 

0.074 0.110 0.210 0.340 0.090 0.396 0.316 0.084 0.351 0.028 0.005 0.018 

0.008 0.025 0.030 0.042 0.013 0.064 0.030 0.006 0.058 0.010 0.003 0.005 

0.078 0.108 0.129 0.202 0.136 0.314 0.094 0.380 0.404 0.374 0.304 0.085 0.367 0.367 0.371 0.030 0.007 0.031 0.027 0.0

0.057 0.016 0.054 0.057 0.053 0.048 0.012 0.042 0.041 0.039 

Total β-Carotene, μg/mL trans-β-Carotene, μg/mL Total cis-β-Carotene, μg/mL δ-Tocopherol, μg/mL

C

3
Round Robin LXXV Laboratory Results

All Lab Report 

Lab

FSV-BB

FSV-BC

FSV-BD

FSV-BE

FSV-BF

FSV-BFa

FSV-BG

FSV-BH

FSV-BJ

FSV-BK

FSV-BL

FSV-BM

FSV-BN

FSV-BO

FSV-BR

FSV-BS

FSV-BT

FSV-BU

FSV-BV

FSV-BW

FSV-CD

FSV-CE

FSV-CG

FSV-CI

FSV-CO

FSV-CZ

FSV-DD

FSV-DV

FSV-EE

FSV-EZ

FSV-FK

FSV-FZ

FSV-GD

N

Min

Median

Max

eSD

eCV

Npast

Medianpast

SDpast

NAV

NAU

402 403 404 405 406 402 403 404 405 406 402 403 404 405 406 402 403 404 405 406 

0.063 0.210 0.262 0.81 0.256 0.026 0.099 0.118 0.322 0.114 0.010 0.046 0.063 0.036 0.060 0.004 0.016 0.026 0.014 0.027 0

0.062 0.224 0.283 1.02 0.257 0.028 0.117 0.141 0.463 0.131 0.012 0.050 0.068 0.038 0.065

0.057 0.211 0.269 1.05 0.259 nd 0.053 0.066 0.027 0.065 0

0.075 0.226 0.289 1.31 0.303 nq nq 0.057 nq 0.061 

0.054 0.201 0.269 1.01 0.249 0.014 0.075 0.095 0.045 0.092

0.065 0.187 0.227 0.68 0.234 0.005 0.055 0.069 0.028 0.072 0

0.126 0.227 0.302 1.23 0.228 0.081 0.140 0.175 0.681 0.142 0.021 0.046 0.055 0.030 0.055 0

0.058 0.147 0.167 0.58 0.169 0.041 0.129 0.143 0.506 0.147 0.010 0.039 0.048 0.039 0.049 0.004 0.013 0.018 0.021 0.018 0

0.051 0.203 0.263 0.99 0.303 0.010 0.046 0.057 0.031 0.063

0.064 0.236 0.294 0.94 0.289 0.006 0.049 0.064 0.026 0.064

0.060 0.241 0.243 1.17 0.275

0.063 0.222 0.312 1.06 0.321 nq 0.053 0.065 nq 0.063 nq nq 0.028 nq 0.030

0.067 0.224 0.274 0.98 0.281 0.029 0.120 0.141 0.440 0.144 0.014 0.068 0.085 0.060 0.087

0

0.047 0.209 0.245 0.87 0.239 0.009 0.047 0.061 0.028 0.061

0.059 0.166 0.229 0.504 0.221 0

0.068 0.202 0.275 0.85 0.251

15 15 15 15 15 6 6 6 6 6 10 12 13 11 13 2 2 3 2 3 

0.047 0.147 0.167 0.58 0.169 0.026 0.099 0.118 0.322 0.114 0.005 0.039 0.048 0.026 0.049 0.004 0.013 0.018 0.014 0.018 0

0.063 0.211 0.269 0.99 0.257 0.035 0.125 0.142 0.483 0.143 0.010 0.050 0.064 0.031 0.063 0.004 0.014 0.026 0.018 0.027 0

0.126 0.241 0.312 1.31 0.321 0.081 0.166 0.229 0.681 0.221 0.021 0.075 0.095 0.060 0.092 0.004 0.016 0.028 0.021 0.030 0

0.007 0.019 0.030 0.18 0.034 0.012 0.017 0.019 0.049 0.012 0.004 0.005 0.007 0.007 0.003 0

12 9 11 18 13 34 13 13 10 8 44 11 12 24 5 

22 15 0 16 0 8 7 0 7 0 17 14 0 16 0 7 6 0 5 0 

0.071 0.220 0.93 0.037 0.115 0.408 0.011 0.051 0.032 0.006 0.018 0.023 0

0.019 0.027 0.17 0.008 0.018 0.095 0.005 0.011 0.014 0.002 0.003 0.008 0

0.063 0.211 0.269 0.99 0.257 0.035 0.125 0.142 0.483 0.143 0.010 0.050 0.064 0.031 0.063 0.026 0.027 0

0.019 0.051 0.062 0.18 0.060 0.012 0.022 0.025 0.092 0.025 0.004 0.012 0.015 0.008 0.015 0

Total β-Cryptoxanthin, μg/mL Total α-Cryptoxanthin, μg/mL Total Lycopene, μg/mL trans-Lycopene, μg/mL

C

4
Round Robin LXXV Laboratory Results

All Lab Report 

Lab

FSV-BB

FSV-BC

FSV-BD

FSV-BE

FSV-BF

FSV-BFa

FSV-BG

FSV-BH

FSV-BJ

FSV-BK

FSV-BL

FSV-BM

FSV-BN

FSV-BO

FSV-BR

FSV-BS

FSV-BT

FSV-BU

FSV-BV

FSV-BW

FSV-CD

FSV-CE

FSV-CG

FSV-CI

FSV-CO

FSV-CZ

FSV-DD

FSV-DV

FSV-EE

FSV-EZ

FSV-FK

FSV-FZ

FSV-GD

N

Min

Median

Max

eSD

eCV

Npast

Medianpast

SDpast

NAV

NAU

402 403 404 405 406 402 403 404 405 406 402 403 404 405 406 402 403 404 

0.010 0.038 0.037 0.053 0.048 0.043 0.128 0.117 0.228 0.120

0.360 1.02 1.04 1.97 1.060 1.509 0.955 1.86

0.038 0.111 0.110 0.172 0.111

0.007 0.048 0.038 0.029 0.036 0.024 0.115 0.097 0.131 0.093

0.388 1.09 0.66 1.40 0.809

0.013 0.091 0.091 0.113 0.075

0.009 0.019 0.012 0.020 0.011 0.033 0.125 0.102 0.151 0.104 0.320 0.84 0.90 1.54 0.840

0.006 0.032 0.029 0.022 0.029 0.037 0.130 0.113 0.145 0.110

0.009 0.034 0.028 0.027 0.032 0.040 0.119 0.091 0.141 0.102 0.252 0.69 0.73 1.53 0.585

0.025 0.105 0.102 0.157 0.090

0.030 0.108 0.100 0.121 0.097

0.250 0.71 0.74 1.15 0.705

nq 0.125 0.108 0.160 0.116

0.035 0.110 0.100 0.144 0.100

0.006 0.022 0.019 0.014 0.025 0.024 0.084 0.080 0.116 0.085 0.270 0.85 0.88 1.03 0.850 0.399 0.232 0.34

0.044 0.112 0.110 0.143 0.112

0.640 0.74 1.26 1.94 1.007

0.298 0.93 0.97 1.44 0.874

0.323 0.68 0.78 1.18 0.749

0.400 0.260 0.41

0.300 0.83 0.76 1.27 0.800

6 6 6 6 6 12 13 13 13 13 10 10 10 10 10 3 3 

0.006 0.019 0.012 0.014 0.011 0.013 0.084 0.080 0.113 0.075 0.250 0.68 0.66 1.03 0.585 0.399 0.232 0.34

0.008 0.033 0.029 0.024 0.030 0.034 0.112 0.102 0.144 0.102 0.310 0.84 0.83 1.42 0.825 0.400 0.260 0.41

0.010 0.048 0.038 0.053 0.048 0.044 0.130 0.117 0.228 0.120 0.640 1.09 1.26 1.97 1.060 1.509 0.955 1.86

0.002 0.012 0.013 0.007 0.008 0.011 0.011 0.012 0.019 0.013 0.067 0.16 0.14 0.29 0.093

28 37 47 27 27 32 9 12 13 13 22 20 17 20 11

9 6 0 7 0 19 15 0 16 0 7 8 0 9 0 0 0 

0.010 0.034 0.027 0.038 0.111 0.148 0.323 0.86 1.36

0.004 0.012 0.013 0.008 0.020 0.036 0.027 0.10 0.29

0.008 0.033 0.029 0.024 0.030 0.034 0.112 0.102 0.144 0.102 0.310 0.84 0.83 1.42 0.825 0.400 0.260 0.41

0.003 0.012 0.013 0.007 0.009 0.011 0.023 0.021 0.030 0.021 0.067 0.16 0.14 0.29 0.093

Phylloquinone Total Zeaxanthin, μg/mL Total Lutein&Zeaxanthin, μg/mL Coenzyme Q10, μg/mL

C

5
Round Robin LXXV Laboratory Results

All Lab Report Page 5 / 6

Analytes Reported By One Laboratory

Values in μg/mL

Analyte Code 402 403 404 405 406

25-hydroxyvitamin D FSV-BH 0.014 0.007 0.021 0.022 0.020

Phytoene FSV-BS nd nd nd nd nd

Phytofluene FSV-BS 0.024 0.058 0.056 0.265 0.058

Term 

N

Min

Median

Max

eSD

eCV

Npast

Medianpast

SDpast

NAV

NAU

nd

nq

≥x

italics Not explicitly reported but calculated by NIST from reported values

 NIST Assigned Uncertainty: maximum of (0.05*NAV, eSD, SDpast, eSDcalc)

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

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

 Detected but not quantitatively determined

 Concentration greater than or equal to x

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

 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)

 NIST Assigned Value: Median for analytes reported by ≥ 5 labs

Table 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

C6
Round Robin LXXV Laboratory Results

All Lab Report Page 6 / 6

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

FSV-BB 1 1 1 1 1 1 1 1 2 1 Lab Participant code

FSV-BC 2 1 TR Total Retinol

FSV-BD 2 2 aT α-Tocopherol

FSV-BE 3 1 2 1 g/bT γ/β-Tocopherol

FSV-BF 1 1 2 bC Total β-Carotene

FSV-BFa 2 2 tbC trans-β-Carotene

FSV-BG 1 1 1 1 1 1 1 3 2 aC Total α-Carotene

FSV-BH 2 2 1 2 2 1 1 1 TLy Total Lycopene

FSV-BJ 1 1 1 3 1 1 2 1 1 TbX Total β-Cryptoxanthin

FSV-BK 1 1 TLu Total Lutein

FSV-BL 1 1 TZ Total Zeaxanthin

FSV-BM 2 2 L&Z Total Lutein & Zeaxanthin

FSV-BN 1 2 1 3 1 2 2

FSV-BO 1 1 2 1 1 1 1 1 1 1 n number of participants providing quantitative data

FSV-BR 1 1 2 1 % 1 Percent of CS = 1 (within 1 SD of medians)

FSV-BS 1 1 2 2 1 1 1 % 2 Percent of CS = 2 (within 2 SD of medians)

FSV-BT 1 1 2 1 1 1 2 1 1 % 3 Percent of CS = 3 (within 3 SD of medians)

FSV-BU 2 1 1 1 1 1 1 1 % 4 Percent of CS = 4 (3 or more SD from medians)

FSV-BV 2 1 1 1 1 1 1

FSV-BW 4 2 4 3 4 1 1

FSV-CD 1 1 2 1 1 1 1

FSV-CE 1 3 4 1

FSV-CG 1 1 1 1 1 1 1 3

FSV-CI 2 2 1 1 3 1 1 1

FSV-CO 1 1 1 1 1 1

FSV-CZ 2 1 1 2

FSV-DD 2

FSV-DV 1 2

FSV-EZ 1 1 1 2 2 1

FSV-FK 1 1 1 2

FSV-FZ 2 1 1 1

FSV-GD 1 1 1 1 1 1 1

n 31 29 18 23 6 13 15 13 8 6 13

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

% 1 58 69 72 70 67 69 87 77 75 67 85

% 2 35 28 22 17 33 8 13 15 25 17 15

% 3 3 3 0 9 0 15 0 8 0 17 0

% 4 3 0 6 4 0 8 0 0 0 0 0

Comparability Summary

“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:

CS = 



 



 



 



 ++ 22 MINIMUM 4,INTEGER C1 AP

C = Concordance = 

you

N

1i i

i i

N

NAU

You Median you

∑=

−

AP = Apparent Precision = 1N

NAU

You Median

you

N

1i

2

i

i i

you

−















 − ∑=

NAU = NIST Assigned Uncertainty

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.

C7
Appendix D. Representative Individualized Report for RR75 

Each participant in RR75 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:

• Total Retinol

• Retinyl Palmitate

• α-Tocopherol 

• γ/β-Tocopherol 

• Total β-Carotene

• Total α-Carotene

• Total Lycopene

• trans-Lycopene

• Total β-Cryptoxanthin 

• Total Lutein

• Total Zeaxanthin

• Total Lutein & Zeaxanthin

• Coenzyme Q10 

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

by participant FSV-BB. 

D1 
 Set 7 of 33

Individualized Report 

Individualized Round Robin LXXV Report: FSV-BB

Summary

Serum 402 Serum 403 Serum 404 Serum 405 

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

Total Retinol 0.394 0.390 29 0.370 0.357 29 1.160 1.147 29 0.657 0.660 29 

Retinyl Palmitate 0.08 0.10 6 0.0 0.0 5 0.4 0.5 7 0.09 0.10 6 

α-Tocopherol 7.24 6.92 29 7.03 6.53 29 8.99 8.22 29 18.22 18.64 29 

γ/β-Tocopherol 1.369 1.359 18 1.865 1.803 18 3.829 3.829 18 2.273 2.293 18 

δ-Tocopherol 0.078 0.078 3 0.094 0.108 3 0.129 0.129 3 0.202 0.202 3 

Total β-Carotene 0.314 0.314 21 0.082 0.094 21 0.415 0.380 21 0.371 0.404 21 

trans-β-Carotene 0.286 0.304 6 0.079 0.085 6 0.378 0.367 6 0.338 0.367 6 

Total cis-β-Carotene 0.028 0.030 4 0.003 0.007 4 0.037 0.031 4 0.033 0.027 4 

Total α-Carotene 0.014 0.017 12 0.006 0.008 12 0.043 0.043 14 0.008 0.015 12 

Total Lycopene 0.063 0.063 15 0.210 0.211 15 0.262 0.269 15 0.807 0.990 15 

trans-Lycopene 0.026 0.035 6 0.099 0.125 6 0.118 0.142 6 0.322 0.483 6 

Total β-Cryptoxanthin 0.010 0.010 10 0.046 0.050 12 0.063 0.064 13 0.036 0.031 11 

Total α-Cryptoxanthin 0.004 2 0.016 2 0.026 0.026 3 0.014 2 

Total Lutein 0.033 0.024 7 0.090 0.088 8 0.080 0.072 8 0.175 0.123 8 

Total Zeaxanthin 0.010 0.008 6 0.038 0.033 6 0.037 0.029 6 0.053 0.024 6 

Total Lutein&Zeaxanthin 0.043 0.034 12 0.128 0.112 13 0.117 0.102 13 0.228 0.144 13 

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

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

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

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

Micronutrients Measurement Quality Assurance Program

National Institute of Standards and Technology 

100 Bureau Drive Stop 8392 

Gaithersburg, MD 20899-8392 USA Email: 

D

2
 Set 7 of 33

Individualized Report Page 2 / 14

Individualized RR LXXV Report: FSV-BB

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 Comments History

#402 Lyophilized, augmented, multi-donor 31#195, 35#214, 43#244, 60#328, 64#347

#403 Fresh-frozen, native, multi-donor: SRM 968e I 66#357, 67#365, 69#375, 72#389, 74#398

#404 Fresh-frozen, augmented {tR,RP,βT}, single-donor Initial distribution

#405 Fresh-frozen, native, multi-donor: SRM 968e III 66#359, 67#363, 69#373, 70#379, 74#400

#406 Fresh-frozen, augmented {cR,γT}, single-donor Initial distribution

Total Retinol, μg/mL

195214244328347402357365375389398403359363373379400405404406

[Analyte], μg/mL Apparent Precision, SD

Concordance, SD

Your [Analyte], μg/mL

Median [Analyte], μg/mL

Long-term Precision, SD

Apparent Precision, SD

You, this RR

You, past RRs Others, this RR

1st Quartile (25%)

Median (50%)

3rd Quartile (75%)

Expectation

You, ≥x, this RR

You, ≥x, past RRs

D3
 Set 7 of 33

Individualized Report Page 3 / 14

Individualized RR LXXV Report: FSV-BB

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 Comments History

#402 Lyophilized, augmented, multi-donor 31#195, 35#214, 43#244, 60#328, 64#347

#403 Fresh-frozen, native, multi-donor: SRM 968e I 66#357, 67#365, 69#375, 72#389, 74#398

#404 Fresh-frozen, augmented {tR,RP,βT}, single-donor Initial distribution

#405 Fresh-frozen, native, multi-donor: SRM 968e III 66#359, 67#363, 69#373, 70#379, 74#400

#406 Fresh-frozen, augmented {cR,γT}, single-donor Initial distribution

Retinyl Palmitate, μg/mL

195214244328347402357365375389398403359363373379400405404406

[Analyte], μg/mL Apparent Precision, SD

Concordance, SD

Your [Analyte], μg/mL

Median [Analyte], μg/mL

Long-term Precision, SD

Apparent Precision, SD

You, this RR

You, past RRs Others, this RR

1st Quartile (25%)

Median (50%)

3rd Quartile (75%)

Expectation

You, ≥x, this RR

You, ≥x, past RRs

D4
 Set 7 of 33

Individualized Report Page 4 / 14

Individualized RR LXXV Report: FSV-BB

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 Comments History

#402 Lyophilized, augmented, multi-donor 31#195, 35#214, 43#244, 60#328, 64#347

#403 Fresh-frozen, native, multi-donor: SRM 968e I 66#357, 67#365, 69#375, 72#389, 74#398

#404 Fresh-frozen, augmented {tR,RP,βT}, single-donor Initial distribution

#405 Fresh-frozen, native, multi-donor: SRM 968e III 66#359, 67#363, 69#373, 70#379, 74#400

#406 Fresh-frozen, augmented {cR,γT}, single-donor Initial distribution

α-Tocopherol, μg/mL

195214244328347402357365375389398403359363373379400405404406

[Analyte], μg/mL Apparent Precision, SD

Concordance, SD

Your [Analyte], μg/mL

Median [Analyte], μg/mL

Long-term Precision, SD

Apparent Precision, SD

You, this RR

You, past RRs Others, this RR

1st Quartile (25%)

Median (50%)

3rd Quartile (75%)

Expectation

You, ≥x, this RR

You, ≥x, past RRs

D5
 Set 7 of 33

Individualized Report Page 5 / 14

Individualized RR LXXV Report: FSV-BB

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 Comments History

#402 Lyophilized, augmented, multi-donor 31#195, 35#214, 43#244, 60#328, 64#347

#403 Fresh-frozen, native, multi-donor: SRM 968e I 66#357, 67#365, 69#375, 72#389, 74#398

#404 Fresh-frozen, augmented {tR,RP,βT}, single-donor Initial distribution

#405 Fresh-frozen, native, multi-donor: SRM 968e III 66#359, 67#363, 69#373, 70#379, 74#400

#406 Fresh-frozen, augmented {cR,γT}, single-donor Initial distribution

γ/β-Tocopherol, μg/mL

195214244328347402357365375389398403359363373379400405404406

[Analyte], μg/mL Apparent Precision, SD

Concordance, SD

Your [Analyte], μg/mL

Median [Analyte], μg/mL

Long-term Precision, SD

Apparent Precision, SD

You, this RR

You, past RRs Others, this RR

1st Quartile (25%)

Median (50%)

3rd Quartile (75%)

Expectation

You, ≥x, this RR

You, ≥x, past RRs

D6
 Set 7 of 33

Individualized Report Page 6 / 14

Individualized RR LXXV Report: FSV-BB

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 Comments History

#402 Lyophilized, augmented, multi-donor 31#195, 35#214, 43#244, 60#328, 64#347

#403 Fresh-frozen, native, multi-donor: SRM 968e I 66#357, 67#365, 69#375, 72#389, 74#398

#404 Fresh-frozen, augmented {tR,RP,βT}, single-donor Initial distribution

#405 Fresh-frozen, native, multi-donor: SRM 968e III 66#359, 67#363, 69#373, 70#379, 74#400

#406 Fresh-frozen, augmented {cR,γT}, single-donor Initial distribution

Total β-Carotene, μg/mL

195214244328347402357365375389398403359363373379400405404406

[Analyte], μg/mL Apparent Precision, SD

Concordance, SD

Your [Analyte], μg/mL

Median [Analyte], μg/mL

Long-term Precision, SD

Apparent Precision, SD

You, this RR

You, past RRs Others, this RR

1st Quartile (25%)

Median (50%)

3rd Quartile (75%)

Expectation

You, ≥x, this RR

You, ≥x, past RRs

D7
 Set 7 of 33

Individualized Report Page 7 / 14

Individualized RR LXXV Report: FSV-BB

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 Comments History

#402 Lyophilized, augmented, multi-donor 31#195, 35#214, 43#244, 60#328, 64#347

#403 Fresh-frozen, native, multi-donor: SRM 968e I 66#357, 67#365, 69#375, 72#389, 74#398

#404 Fresh-frozen, augmented {tR,RP,βT}, single-donor Initial distribution

#405 Fresh-frozen, native, multi-donor: SRM 968e III 66#359, 67#363, 69#373, 70#379, 74#400

#406 Fresh-frozen, augmented {cR,γT}, single-donor Initial distribution

Total α-Carotene, μg/mL

195214244328347402357365375389398403359363373379400405404406

[Analyte], μg/mL Apparent Precision, SD

Concordance, SD

Your [Analyte], μg/mL

Median [Analyte], μg/mL

Long-term Precision, SD

Apparent Precision, SD

You, this RR

You, past RRs Others, this RR

1st Quartile (25%)

Median (50%)

3rd Quartile (75%)

Expectation

You, ≥x, this RR

You, ≥x, past RRs

D8
 Set 7 of 33

Individualized Report Page 8 / 14

Individualized RR LXXV Report: FSV-BB

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 Comments History

#402 Lyophilized, augmented, multi-donor 31#195, 35#214, 43#244, 60#328, 64#347

#403 Fresh-frozen, native, multi-donor: SRM 968e I 66#357, 67#365, 69#375, 72#389, 74#398

#404 Fresh-frozen, augmented {tR,RP,βT}, single-donor Initial distribution

#405 Fresh-frozen, native, multi-donor: SRM 968e III 66#359, 67#363, 69#373, 70#379, 74#400

#406 Fresh-frozen, augmented {cR,γT}, single-donor Initial distribution

Total Lycopene, μg/mL

195214244328347402357365375389398403359363373379400405404406

[Analyte], μg/mL Apparent Precision, SD

Concordance, SD

Your [Analyte], μg/mL

Median [Analyte], μg/mL

Long-term Precision, SD

Apparent Precision, SD

You, this RR

You, past RRs Others, this RR

1st Quartile (25%)

Median (50%)

3rd Quartile (75%)

Expectation

You, ≥x, this RR

You, ≥x, past RRs

D9
 Set 7 of 33

Individualized Report Page 9 / 14

Individualized RR LXXV Report: FSV-BB

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 Comments History

#402 Lyophilized, augmented, multi-donor 31#195, 35#214, 43#244, 60#328, 64#347

#403 Fresh-frozen, native, multi-donor: SRM 968e I 66#357, 67#365, 69#375, 72#389, 74#398

#404 Fresh-frozen, augmented {tR,RP,βT}, single-donor Initial distribution

#405 Fresh-frozen, native, multi-donor: SRM 968e III 66#359, 67#363, 69#373, 70#379, 74#400

#406 Fresh-frozen, augmented {cR,γT}, single-donor Initial distribution

trans-Lycopene, μg/mL

195214244328347402357365375389398403359363373379400405404406

[Analyte], μg/mL Apparent Precision, SD

Concordance, SD

Your [Analyte], μg/mL

Median [Analyte], μg/mL

Long-term Precision, SD

Apparent Precision, SD

You, this RR

You, past RRs Others, this RR

1st Quartile (25%)

Median (50%)

3rd Quartile (75%)

Expectation

You, ≥x, this RR

You, ≥x, past RRs

D10
 Set 7 of 33

Individualized Report Page 10 / 14

Individualized RR LXXV Report: FSV-BB

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 Comments History

#402 Lyophilized, augmented, multi-donor 31#195, 35#214, 43#244, 60#328, 64#347

#403 Fresh-frozen, native, multi-donor: SRM 968e I 66#357, 67#365, 69#375, 72#389, 74#398

#404 Fresh-frozen, augmented {tR,RP,βT}, single-donor Initial distribution

#405 Fresh-frozen, native, multi-donor: SRM 968e III 66#359, 67#363, 69#373, 70#379, 74#400

#406 Fresh-frozen, augmented {cR,γT}, single-donor Initial distribution

Total β-Cryptoxanthin, μg/mL

195214244328347402357365375389398403359363373379400405404406

[Analyte], μg/mL Apparent Precision, SD

Concordance, SD

Your [Analyte], μg/mL

Median [Analyte], μg/mL

Long-term Precision, SD

Apparent Precision, SD

You, this RR

You, past RRs Others, this RR

1st Quartile (25%)

Median (50%)

3rd Quartile (75%)

Expectation

You, ≥x, this RR

You, ≥x, past RRs

D11 
 Set 7 of 33

Individualized Report Page 11 / 14

Individualized RR LXXV Report: FSV-BB

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 Comments History

#402 Lyophilized, augmented, multi-donor 31#195, 35#214, 43#244, 60#328, 64#347

#403 Fresh-frozen, native, multi-donor: SRM 968e I 66#357, 67#365, 69#375, 72#389, 74#398

#404 Fresh-frozen, augmented {tR,RP,βT}, single-donor Initial distribution

#405 Fresh-frozen, native, multi-donor: SRM 968e III 66#359, 67#363, 69#373, 70#379, 74#400

#406 Fresh-frozen, augmented {cR,γT}, single-donor Initial distribution

Total Lutein, μg/mL

195214244328347402357365375389398403359363373379400405404406

[Analyte], μg/mL Apparent Precision, SD

Concordance, SD

Your [Analyte], μg/mL

Median [Analyte], μg/mL

Long-term Precision, SD

Apparent Precision, SD

You, this RR

You, past RRs Others, this RR

1st Quartile (25%)

Median (50%)

3rd Quartile (75%)

Expectation

You, ≥x, this RR

You, ≥x, past RRs

D12
 Set 7 of 33

Individualized Report Page 12 / 14

Individualized RR LXXV Report: FSV-BB

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 Comments History

#402 Lyophilized, augmented, multi-donor 31#195, 35#214, 43#244, 60#328, 64#347

#403 Fresh-frozen, native, multi-donor: SRM 968e I 66#357, 67#365, 69#375, 72#389, 74#398

#404 Fresh-frozen, augmented {tR,RP,βT}, single-donor Initial distribution

#405 Fresh-frozen, native, multi-donor: SRM 968e III 66#359, 67#363, 69#373, 70#379, 74#400

#406 Fresh-frozen, augmented {cR,γT}, single-donor Initial distribution

Total Zeaxanthin, μg/mL

195214244328347402357365375389398403359363373379400405404406

[Analyte], μg/mL Apparent Precision, SD

Concordance, SD

Your [Analyte], μg/mL

Median [Analyte], μg/mL

Long-term Precision, SD

Apparent Precision, SD

You, this RR

You, past RRs Others, this RR

1st Quartile (25%)

Median (50%)

3rd Quartile (75%)

Expectation

You, ≥x, this RR

You, ≥x, past RRs

D13
 Set 7 of 33

Individualized Report Page 13 / 14

Individualized RR LXXV Report: FSV-BB

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 Comments History

#402 Lyophilized, augmented, multi-donor 31#195, 35#214, 43#244, 60#328, 64#347

#403 Fresh-frozen, native, multi-donor: SRM 968e I 66#357, 67#365, 69#375, 72#389, 74#398

#404 Fresh-frozen, augmented {tR,RP,βT}, single-donor Initial distribution

#405 Fresh-frozen, native, multi-donor: SRM 968e III 66#359, 67#363, 69#373, 70#379, 74#400

#406 Fresh-frozen, augmented {cR,γT}, single-donor Initial distribution

Total Lutein&Zeaxanthin, μg/mL

195214244328347402357365375389398403359363373379400405404406

[Analyte], μg/mL Apparent Precision, SD

Concordance, SD

Your [Analyte], μg/mL

Median [Analyte], μg/mL

Long-term Precision, SD

Apparent Precision, SD

You, this RR

You, past RRs Others, this RR

1st Quartile (25%)

Median (50%)

3rd Quartile (75%)

Expectation

You, ≥x, this RR

You, ≥x, past RRs

D14
 Set 7 of 34

8/6/2014 

Total Retinol α-Tocopherol Total β-Carotene To

Retinyl palmitate γ/β-Tocopherol Total Lutein tra

Total α-Carotene Total β-Cryptoxanthin Total Lutein&Zeaxanthin Co

Individualized Round Robin LXXV Report: FSV-BB 

Graphical Comparability Summary

D1

5
Appendix E. Shipping Package Inserts for RR40 

The following three items were included in each package shipped to an RR40 participant:

• Cover letter

• Analysis of Control Materials and Test Samples Datasheet

• Packing List and Shipment Receipt Confirmation Form

The RR41 samples were packed in a sealed waterproof bag and labeled: 

Cover letters describing the RR40 and RR41 studies, datasheets for both studies, and 

packing lists for both studies were enclosed in a sealed waterproof bag placed at the top 

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

NIST MMQAP-VC: RR 40

Micronutrients Measurement Vitamin C

Quality Assurance Program

Winter 2014 Controls & Samples 

Results due on or before:

April 18, 2014

E1 
February 10, 2014 

Dear Colleague: 

UNITED STATES DEPARTMENT OF COMMERCE 

National Institute of Standards and Technology 

Gaithersburg, Maryland 20888-

The samples within this package constitute Vitamin C Round Robin 40 (RR40) of the 2014 

Micronutrients Measurement Quality Assurance Program. RR40 consists of one vial each of 

four frozen serum test samples (#401, #402 #403, and #404) and one vial each of two frozen 

control sera (CS#3 and CS#4). These materials are in sealed ampoules. They were prepared by \ 

adding equal volumes of 10% MP A to spiked human serum. We have checked the samples for 

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

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

analyzed and reported. 

Please use the control sera to validate the performance of your measurement system before you 

analyze the test samples. The target value for CS#3 is (15.5 ± 1.6; 13.9 to 17.1) μmol/L and the 

target for CS#4 is ( 46.1 ± 4.6; 41.5 to 50, 7) μmol/L. We expect your results for both of these 

controls to be within this ± 10% target range. If your results are significantly outside this range, 

your analysis system may not be suited to the analysis ofMPA-preserved samples. In this case, 

please do not proceed to the analysis of the test samples but contact us at jbthomas@nist.gov or 

301-975-3120. 

The test samples and control sera should be defrosted by warming at 20 °C for not more than 10 

min otherwise some irreversible degradation may occur. Please be aware that sample contact 

with any oxidant-contaminated surface (vials, glassware, etc.) may degrade your measurement 

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

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

degradation if you observe unusually large variation in replicate analyses. 

Please measure the total ascorbic acid in each ampoule in duplicate, reporting in units of μmol/(L 

sample solution) rather than μmol/(L serum used to prepare the sample). Please email 

(david.duewer@nist.gov) or fax (301-977-0685) your results to us as soon as possible but no 

later than April 18, 2014. 

Please report your results by e-mail to david.duewer@nist.gov or fax to 301-977-0685. If you 

have questions or comments regarding the studies, please contact us at 301-975-3120 (Jeanice); 

jbthomas@nist. ov or 301-975-3935 (Dave); david.duewer@nist.gov. 

esearch Chemist 

Chemical Sciences Division 

Material Measurement Laboratory 

David L. Duewer, Ph.D. 

Research Chemometrician 

Chemical Sciences Division 

Material Measurement Laboratory 

Enclosure: RR40 Report Form for Control and Test Sample Analyses 

NISI E2
Participant #: Date: 

Vitamin C Round Robin 40 

NIST Micronutrient Measurement Quality Assurance Program

Analysis of Control Materials and Test Samples

Sample Replicate 1 Replicate 2 Units

Control serum CS#3 μmol/L of Sample

Target: (15.5 ±1.6) μmol/L

Control serum CS#4 μmol/L of Sample

Target: (46.1 ±4.6) μmol/L

Test sample #401 μmol/L of Sample

Test sample #402 μmol/L of Sample

Test sample #403 μmol/L of Sample

Test sample #404 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:

Nature of samples you typically analyze: native | MPA-preserved | DTT-preserved | Other

If “Other”, please describe:

COMMENTS:

Please return by April 18, 2014

MMQAP Fax: 301-977-0685 

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

Gaithersburg, MD 20899-8392 

E3
Participant #: ________ Date: _____________

Mail: M2QAP

 NIST, Stop 6392

 Gaithersburg, MD 20899-6392

Fax: 301-977-0685

Email: David.Duewer@NIST.gov

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

Label Form

VitC #401 Liquid frozen (1:1 serum:10% MPA) SRM970 Lv1

VitC #402 Liquid frozen (1:1 serum:10% MPA) Sam - 30's

VitC #403 Liquid frozen (1:1 serum:10% MPA) SRM970 Lv2

VitC #404 Liquid frozen (1:1 serum:10% MPA) Sam - 50's

CS#3 Liquid frozen (1:1 serum:10% MPA) Red

CS#4 Liquid frozen (1:1 serum:10% MPA) Orange

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) Email (david.duewer@nist.gov) or fax (301-977-0685) us the

following information:

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

Your prompt return of this information is appreciated.

The M2QAP Gang

Packing List and Shipment Receipt Confirmation Form

NIST Micronutrients Measurement Quality Assurance Program

Vitamin C Round Robin 40

E4
Appendix F. Final Report for RR40 

The following six pages are the final report for RR40 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 13, 2014 

Dear Colleague:

Enclosed is the summary report of the results for Round Robin 40 (RR40) for the measurement of total ascorbic 

acid (TAA, 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 robust median absolute deviation from 

the median is used as an estimate of the consensus interlaboratory standard deviation (eSD). We estimate the 

coefficient of interlaboratory variation (eCV) as 100×eSD/median. 

RR40 consisted of four test samples (#401, #402 #403, and #404) and one vial each of two frozen control serum 

control samples (CS #3 and CS #4). 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 www.nist.gov/srm; 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.

We are pleased to announce that MMQAP participant Professor Garry Duthie of the Rowett Institute of Nutrition 

and Health, University of Aberdeen, Scotland is providing the (free) on-line recipe book Stovies Reloaded: 

Traditional Scottish Recipes Made Healthier at http://www.abdn.ac.uk/rowett/policy-industry/stovies.php. Prof. 

Duthie states that “Stovies Reloaded” is our light-hearted take on traditional Scottish recipes and how they can 

be adapted in the light of increased nutritional knowledge. ... We hope that this book may play a small part in 

encouraging people to rediscover cooking skills, take an interest in traditional Scottish fare and eat a more 

healthy diet.” This website also provides links to a wealth of other information developed at the Rowett Institute 

relating to nutrition, food safety, and human health.

The results for vitamin C in serum RR41 and fat-soluble vitamins and carotenoids in serum RR41 are due on or 

before September 15, 2014. We will send you a reminder in August. If you have questions or concerns 

regarding this report, please contact David Duewer at 301-975-3935; e-mail: david.duewer@nist.gov or me at 

301-975-3120; e-mail: jbthomas@nist.gov; or fax: 301-977-0685. 

Sincerely,

Jeanice Brown Thomas, M.B.A. David L. Duewer, Ph.D. 

Research Chemist Research Chemometrician

Chemical Sciences Division Chemical Sciences Division

Material Measurement Laboratory Material Measurement Laboratory

Enclosures 

cc: L. C. Sander 

UNITED STATES DEPARTMENT OF COMMERCE

National Institute of Standards and Technology

Gaithersburg, Maryland 20899-8390

F2
The NIST MMQAP Vitamin C Round Robin 40 (RR40) report consists of: 

Page “Individualized” Report

1 Summary of your reported values for the two serum control and four serum test samples.

2 Graphical summary of measurements made on the RR40 test samples. 

3 Your RR40 measurements as a function of their expected values. 

Page “All-Lab” Report

1 A tabulation of results and summary statistics for total ascorbic acid [TAA] in the RR40 

control and test samples. Results and summary statistics are also presented for the test

samples calibrated to the results for the control samples. The consensus [TAA] content and 

inter-participant standard deviations are estimated using robust estimators. 

Serum-Based Samples. Two serum controls and four test samples were distributed in RR40. 

CS#3 a (15.4 ±0.4) μmol/L material ampouled in 2009 

CS#4 a (46.2 ±1.2) μmol/L material ampouled in 2009

S40:1 SRM 970 level 2, ampouled in mid-1998, previously distributed as a test sample in RRs 11 to 

15, 18, 20 22, 25, 29, 36, 37, and 39 

S40:2 For most participants, this was a blank material of nearly zero [TAA] content, ampouled in 

2001, and previously distributed in RRs 16, 19, 21, 23, 26, 29, and 38. Unfortunately, due to 

a labelling error four participants received augmented materials. The results for these misslabeled samples agree well with the historical values for materials that were stored in the 

same container as the blank (these values are displayed on page 3 of the affected participants’ 

Individualized Reports.) However, since our primary purpose in distributing blank samples is 

to assess current detection/quantification limits, the results for all of the miss-labeled samples 

are recorded in the All-Lab Report as “ne” (short for NIST error.)

S40:3 Ampouled in late 2009, previously distributed in RRs 32, 33, 35, and 38 

S40:4 Ampouled in late 2009, previously distributed in RRs 34, 36, and 38 

Results. 

1) The reported [TAA] contents of the two control sera, CS#3 and CS#4, are unchanged from the values

estimated for these materials when they were distributed as test samples.

2) All participants who received the intended blank material, S40:2, reported either suitably small values

or quantification limits. We interpret [TAA] = 0 as “not detected” (and vice versa).

3) There is no evidence for any significant change in the [TAA] level or interlaboratory variability for

samples S40:1, S40:3, and S40:4.

4) The primary focus of these VitC QAP studies has been and remains improving interlaboratory

comparability of [TAA] measurements. In addition to providing you with objective assessment of

your results against the community’s consensus and helping to certify SRM 970, we have used these

studies to explore other ways to further improve comparability. Chief among these has been the use

of various control materials to linearly recalibrate your measurement systems:

[TAA]ControlReported = a + b × [TAA]ControlReference

Summary Report F3 1 / 4 
where the [TAA]ControlReported are the reported values for two or more control materials, 

[TAA]ControlReference are established reference values for these materials, and a and b are the intercept 

and slope of the linear calibration function. The (re)calibrated values for test samples are then given 

by:

[TAA]TestCalibrated = ([TAA]TestReported – a) / b .

Beginning in 1996, we distributed a solid ascorbic acid control material and asked you to 

gravimetrically prepare solutions of known [TAA] in 5% MPA. In addition to enabling you to 

independently verify the performance of your measurement systems before measuring the test 

samples, the information you provided for these solutions enabled us to determine if the use of a 

common simple-matrix calibrant could improve comparability. 

Figure 1 plots a robust estimate of interlaboratory standard deviation, eSD, as a function of the 

consensus median [TAA] value for the 45 samples distributed as test samples from RR26 (2007) 

through RR36 (2012). The red circles represent the {eSD, Median} values for the results as reported. 

The green triangles represent the {eSD, Median} values for those results after recalibration to the 

gravimetrically prepared control solutions. The solid lines represent “best fits” to the non-linear 

function: 

eSD = �αα2 + (ββ × Median)2

where α is the expected constant variability and β is the expected proportional variability. This or 

similar functional relationships are routinely observed in interlaboratory studies whenever the analyte 

content in some samples approaches the quantification limits of a sizable minority of the 

measurement systems.

Figure 1: Estimated Standard Deviation as a Function of Median Value 

Before and After Recalibration to Gravimetrically Prepared [TAA] in 5 % MPA Solutions 

There is no evidence that recalibration to the 5 % MPA solutions improves comparability. (This is the 

primary reason why we stopped distributing the solid AA control with RR36.) 

0

1

2

3

4

5

6

0 20 40 60

Estimated SD (eSD), 

μmol/L

Median, μmol/L

As Reported

As Calibrated

Summary Report F4 2 / 4 
Beginning in RR20 (2004), we periodically distributed the two SRM 970 materials in the same RR, either 

explicitly as controls and/or as test samples. This allowed recalibrating results for the test samples with 

two models: 1) proportional, using regression to estimate a slope, b, when a is zero and 2) linear, solving 

for the a and b of the line between the two points. Figure 2 displays the summary statistics for the 38 

available test samples using both models. The panel to the left displays proportionally recalibrated results 

as solid green triangles; the panel to the right displays the linearly recalibrated values as open green 

triangles.

Figure 2: Estimated Standard Deviation as a Function of Median Value 

before and after Recalibration with SRM 970 Levels I and II

Panel A: Proportional Model (a = 0). Panel B: Linear Model

Proportional recalibration to the SRM 970 materials marginally improves comparability for the very high 

[TAA] content samples, from a limiting relative standard deviation, %RSD = 100 × eSD / Median, of 

about 7.6 % to about 5.7 %. However, it does little for the low [TAA] content materials. Linear 

recalibration is somewhat superior, reducing the % RSD to about 5.4 % and reducing the contentindependent standard deviation from about 1.2 μmol/L to about 0.8 μmol/L. 

While perhaps academically interesting, the improved comparability with either model hardly seems 

worth the effort.

However, the 8.5 μmol/L long-term consensus [TAA] content of SRM 970 Level I is not much greater 

than the quantification limit reported by several participants and the 27.4 μmol/L of SRM 970 Level II is 

less than 50% of the maximum [TAA] content of the samples thus far distributed. To investigate whether 

increasing the [TAA] contents of the control samples used in the recalibration from the relatively low 

values of the SRM 970 materials, beginning with RR34 (2011) we periodically distributed (either 

explicitly as controls and/or as test samples) two new materials, now designated as CS#3 with [TAA] = 

15.2 μmol/L and as CS#4 with [TAA] = 45.9 μmol/L. Figure 3 displays the summary statistics for the 20 

samples that can be recalibrated with these materials, using both the proportional and linear models.

0

1

2

3

4

5

6

0 20 40 60

Estimated SD (eSD), 

μmol/L

Median, μmol/L

As Reported

As Calibrated

0

1

2

3

4

5

6

0 20 40 60

Median, μmol/L

As Reported

As Calibrated

A B

Summary Report F5 3 / 4 
Figure 3: Estimated Standard Deviation as a Function of Median Value 

before and after Recalibration with CS#3 and CS#4 

Panel A: Proportional Model (a = 0). Panel B: Linear Model

The data are as yet too limited for drawing strong conclusions, but the linear recalibration model 

considerably improves comparability for the mid to high [TAA] content samples, essentially reducing the 

expected variability to an almost constant 1 μmol/L independent of [TAA] content.

Our current hypothesis is that interlaboratory comparability is limited by small differences in how 

measurement processes respond to components of the sample matrix other than TAA itself. At least for 

the samples distributed in the VitC QAP, these biases are greatly reduced by using matrix-matched 

calibrants having appropriately designed [TAA] content. Whether this would hold true for real samples is 

an intriguing, but yet unanswerable question. 

0

1

2

3

4

5

6

0 20 40 60

Estimated SD (eSD), 

μmol/L

Median, μmol/L

As Reported

eSD = 0.073 × Median

As Calibrated

0

1

2

3

4

5

6

0 20 40 60

Median, μmol/L

As Reported

eSD = 0.073 × Median

As Calibrated

A B

Summary Report F6 4 / 4 
Appendix G. “All-Lab Report” for RR40 

The following two pages are the “All-Lab Report” for RR40 as provided to all 

participants, with the following exceptions: 

• the participant identifiers (Lab) have been altered.

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

• the Legend page has been added.

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 Ascorb

"Round Robin" 40 - Winter 2014

All Lab Report 

Lab Date CS#3 CS#4 S40:1 S40:2 S40:3 S40:4 b a S40:1' S40:2' S40:3

VC-MB 24/02/14 13.9 47.7 26.8 ne 23.2 59.9 1.10 -2.8 26.9 - 23.6 

VC-MC 18/04/14 15.5 45.0 27.6 ne 23.3 56.2 0.96 0.9 27.8 - 23.3 

VC-MG 07/03/14 15.4 48.5 28.5 1.2 23.7 58.9 1.08 -1.0 27.3 2.0 22.9 

VC-MH 03/03/14 14.5 43.2 23.8 ne 21.7 51.4 0.94 0.2 25.1 - 22.9 

VC-MI 18/04/14 15.6 45.4 28.1 <1.4 24.6 56.4 0.97 0.8 28.1 <0.6 24.4 

VC-MJ 27/03/14 22.0 52.8 33.0 2.3 31.9 69.3 1.01 6.7 26.2 -4.4 25.1 

VC-MN 01/04/14 15.1 44.6 27.5 0.0 22.5 54.8 0.96 0.5 28.1 -0.5 22.9 

VC-NF 10/04/14 16.0 44.7 28.4 0.0 23.5 54.6 0.94 1.7 28.4 -1.8 23.3 

VC-NM 17/04/14 14.1 43.8 24.2 <5.7 20.3 52.1 0.97 -0.7 25.7 <6.6 21.6 

VC-NX 15/04/14 14.5 47.1 27.6 ne 22.1 58.5 1.06 -1.7 27.5 - 22.4 

10 10 10 4 10 10 10 4 10 

15.6 46.3 27.5 0.9 23.7 57.2 27.1 -1.2 23.2 

2.3 2.9 2.5 1.1 3.1 5.1 1.1 2.7 1.0 

13.9 43.2 23.8 0.0 20.3 51.4 25.1 -4.4 21.6 

14.5 44.6 27.0 22.2 54.6 26.4 22.9 

15.3 45.2 27.6 0.6 23.2 56.3 27.4 -1.1 23.1 

15.6 47.6 28.3 23.7 58.8 28.0 23.5 

22.0 52.8 33.0 2.3 31.9 69.3 28.4 2.0 25.1 

1.1 2.5 1.1 1.4 3.6 1.0 0.6 

7 5 4 6 6 4 2 

Samples Calibrated Results: [TAA]' = (TAA-

Total Ascorbic Acid ([TAA]), μmol/L Parameters [TAA]', μmol/L

N

%75

Max

eSD

eCV

Average

SD

Min

%25

Median

G

2
Micronutrients Measurement Quality Assurance Program for Total Ascorb

"Round Robin" 40 - Winter 2014

All Lab Report 

Term Definition

Lab Participant code

Date Date results received at NIST

b Slope and Intercept of the line connecting the expected values

a for control samples CS#3 and CS#4 with the results reported

 by each participant

N Number of quantitative values reported for this analyte

Average Mean of the reported quantitative values

SD Standard deviation of the reported quantitative values

Min Minimum quantitative value reported

%25 First quartile of the reported quantitative values

Median Median (second quartile) of the reported quantitative values

%75 Third quartile of the reported quantitative values

Max Maximum quantitative value reported

eSD Robust standard deviation, estimated using the adjusted

 median absolute deviation from the median (MADe)

eCV Robust Coefficient of Variation, estimated as 100*eSD/Median

<x Concentration less than x

ne NIST error (participant was shipped the wrong sample)

Legend

G

3
Appendix H. Representative “Individualized Report” for RR40 

Each participant in RR40 received an “Individualized Report” reflecting their reported 

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

“VC-MB”.

H1
 Set 2 of 10

Individualized Report Page 1/3

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

07/23/10 33 S33:3 13.4 13.4 1.0 13.4 0.0 7 14.1 1.3 1.1

01/14/11 34 S34:2 13.9 13.9 1.0 13.9 0.0

06/13/11 35 S35:1 15.0 15.5 1.0 15.2 0.4

08/06/12 37 CS#3 10.3 15.0 1.0 12.6 3.3

02/27/13 38 CS#3 13.9 13.9 1.0 13.9 0.0

08/01/13 39 CS#3 15.5 15.5 1.0 15.5 0.0

02/24/14 40 CS#3 13.9 13.9 1.0 13.9 0.0

01/13/10 32 S32:4 45.4 45.9 1.0 45.7 0.4 7 46.6 0.9 1.1

01/14/11 34 S34:3 45.4 45.9 1.0 45.7 0.4

06/13/11 35 S35:4 47.5 47.5 1.0 47.5 0.0

08/06/12 37 CS#4 44.9 48.0 1.0 46.5 2.2

02/27/13 38 CS#4 45.9 44.9 1.0 45.4 0.7

08/01/13 39 CS#4 48.0 47.5 1.0 47.7 0.4

02/24/14 40 CS#4 47.5 48.0 1.0 47.7 0.4

09/25/98 11 S11:2 63.0 62.0 0.5 31.3 0.4 14 28.4 1.3 2.2

02/26/99 12 S12:2 55.0 55.0 0.5 27.5 0.0

03/03/00 13 S13:2 63.0 64.0 0.5 31.8 0.4

03/26/01 14 S14:4 60.9 59.9 0.5 30.2 0.4

09/05/01 15 S15:2 63.0 64.0 0.5 31.8 0.4

12/19/02 18 S18:3 55.8 54.7 0.5 27.6 0.4

03/01/04 20 S20:4 21.7 27.9 1.0 24.8 4.4

03/02/05 22 S22:4 28.4 28.4 1.0 28.4 0.0

05/24/06 25 S25:2 29.4 29.4 1.0 29.4 0.0

06/20/08 29 S29:3 26.8 26.8 1.0 26.8 0.0

03/07/12 36 S36:3 25.8 26.8 1.0 26.3 0.7

08/06/12 37 S37:3 25.8 27.9 1.0 26.8 1.5

08/01/13 39 S39:2 28.4 28.4 1.0 28.4 0.0

02/24/14 40 S40:1 26.8 26.8 1.0 26.8 0.0

02/08/02 16 S16:2 3.1 2.0 0.5 1.3 0.4 5 0.9 0.4 1.4

05/01/03 19 S19:1 5.2 7.2 0.5 3.1 0.7

07/14/04 21 S21:1 <5.2 <5.2 1.0

05/25/05 23 S23:1 0.0 0.0 1.0 0.0 0.0

11/26/06 26 S26:1 0.0 0.0 1.0 0.0 0.0

06/20/08 29 S29:1 0.0 0.0 1.0 0.0 0.0

02/27/13 38 S38:1 <5.2 <5.2 1.0

02/24/14 40 S40:2 ne ne 1.0

01/13/10 32 S32:2 22.2 22.7 1.0 22.5 0.4 5 22.8 0.5 0.8

07/23/10 33 S33:4 23.2 22.7 1.0 23.0 0.4

06/13/11 35 S35:2 23.7 23.7 1.0 23.7 0.0

02/27/13 38 S38:2 21.2 22.2 1.0 21.7 0.7

02/24/14 40 S40:3 23.7 22.7 1.0 23.2 0.7

01/14/11 34 S34:4 56.8 57.3 1.0 57.0 0.4 5 57.5 0.6 1.5

03/07/12 36 S36:1 57.8 56.8 1.0 57.3 0.7

03/07/12 36 S36:4 56.8 55.2 1.0 56.0 1.1

02/27/13 38 S38:4 57.3 56.8 1.0 57.0 0.4

02/24/14 40 S40:4 59.9 59.9 1.0 59.9 0.0

Vitamin C "Round Robin" 40 Report: Participant VC-MB

[TAA] mmol/Lsample

ne = NIST error

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

Micronutrients Measurement Quality Assurance Program Fax: (301) 977-0685

National Institute of Standards and Technology Email: david.duewer@nist.gov

H2
 Set 2 of 10

5/9/2014 ILR_RR40_VC-MB, Page 2 / 3

Vitamin C "Round Robin" 40 Report: Participant VC-MB 

Total Ascorbic Acid, μmol/mL

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

CS#3

CS#4

S39:1

S39:2

S39:3 Distributed in RRs 32,33,35,38

S39:4 Distributed in RRs 34,36(dups),38

Comments

Distributed as an unknown in RRs 33,34,35; as a control in RRs 37,38,39

Distributed as an unknown in RRs 32,34,35; as a control in RRs 37,38,39

SRM970 Lv II; distributed as an unknown in RRs 11,12,13,14,15,18,20,22,25,29,36,37,39

Zero-level control serum, distributed in RRs 16,19,21,23,26,29,38

RR11RR12RR13RR14RR15RR18RR20RR22RR25RR29RR36RR37RR39RR40

S32:2S33:4S35:2S38:2S40:3S34:4S36:1S36:4S38:4S40:4

[Total Ascorbic Acid], μmol/L

Your [Total Ascorbic Acid], μmol/L

Median [Total Ascorbic Acid], μmol/L

You, this RR

You, past RRs

NIST, RR 22

Others, this RR 1st Quartile (25%)

Median (50%)

3rd Quartile (75%) Apparent Precision, SD

Concordance, SD

H3
 Set 2 of 10

5/9/2014 ILR_RR40_VC-MB, Page 3 / 3

Params Values Units

Intercept -1.5 ± 1.1 μmol/L

Slope 1.059 ± 0.031 (Ratio)

N 6

R2 0.9966

RMSE 1.2 μmol/L

Data error-bars are 2×SD

The "Expected" values are the most recent

historical data available for these materials.

NIST Vitamin C Round Robin 40

Laboratory VC-MB

S2a

S1

S3

S4

0

20

40

60

80

0 20 40 60 80

Your Reported [AA]sample, mmol/L

Expected [Total AA]sample, mmol/L

Controls

Unknowns

Least-squares Fit

Y = X

H4