NISTIR 7880-12 

NIST Micronutrients Measurement 

Quality Assurance Program 

Summer 2006 

Comparability Studies 

Results for Round Robin LX 

Fat-Soluble Vitamins and Carotenoids in Human Serum 

and Round Robin 25 Ascorbic Acid in Human Serum 

David L. Duewer 

Jeanice B. Thomas 

 

 

 

 

 

 

NISTIR 7880-12 

NIST Micronutrients Measurement 

Quality Assurance Program 

Summer 2006 

Comparability Studies 

Results for Round Robin LX 

Fat-Soluble Vitamins and Carotenoids in Human Serum 

and Round Robin 25 Ascorbic Acid in Human Serum 

David L. Duewer 

Jeanice B. Thomas 

Chemical Sciences Division 

Materials Measurement Laboratory 

June 2013 

 U.S. Department of Commerce 

Cameron F. Kerry, Acting Secretary 

 National Institute of Standards and Technology 

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

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Abstract 

The National Institute of Standards and Technology coordinates the Micronutrients Measurement 

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

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

Summer 2006 MMQAP measurement comparability improvement studies: 1) Round Robin LX FatSoluble Vitamins and Carotenoids in Human Serum and 2) Round Robin 25 Total Ascorbic Acid in 

Human Serum. The materials for both studies were shipped to participants in May 2006; 

participants were requested to provide their measurement results by September 4, 2006. 

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

Round Robin 25: Vitamin C in Human Serum............................................................................... 2
	

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

Appendix A. Shipping Package Inserts for RR60........................................................................ A1
	

Appendix B. Final Report for RR60 .............................................................................................. B1 

Appendix C. “All-Lab Report” for RR60 ...................................................................................... C1
	

Appendix D. Representative “Individualized Report” for RR60 ............................................... D1
	

Appendix E. Shipping Package Inserts for RR25 ......................................................................... E1
	

Appendix F. Final Report for RR25............................................................................................... F1
	

Appendix G. “All-Lab Report” for RR25..................................................................................... G1
	

Appendix H. Representative “Individualized Report” for RR25............................................... H1
	

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Introduction 

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

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

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

provides participants with measurement comparability assessment through use of interlaboratory 

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

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

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

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

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

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

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

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

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

with the MMQAP coordinators. 

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

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

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

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

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

LX comparability study (hereafter referred to as RR60) received two lyophilized and three liquidfrozen human serum test samples for analysis. Unless multiple vials were previously requested, 

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

May 2006. 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 RR60 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. 

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•	 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 25: Vitamin C in Human Serum 

Participants in the MMQAP Vitamin C in Human Serum Round Robin 25 comparability study 

(hereafter referred to as RR25) received four frozen serum test samples, two frozen control sera, and 

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

participants received one vial of each material. These sample materials were shipped on dry ice to 

participants in May 2006. 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 RR25 consists of three documents: 

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

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

reproduced as Appendix F. 

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

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

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

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

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

is reproduced as Appendix H. 

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References 

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

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

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

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

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

Stability, Intralaboratory Repeatability, and Interlaboratory Reproducibility. Clin Chem 

1996;42(8):1257-1262. 

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

Measurement Quality Assurance Program: Helping Participants Use Interlaboratory Comparison 

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

1999;71(9):1870-1878. 

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Appendix A. Shipping Package Inserts for RR60 

The following three items were included in each package shipped to an RR60 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
May 1, 2006 

Dear Colleague: 

UNITED STATES DEPARTMENT OF COMMERCE 

National lnatitut:e of Standards and Technology 

Gaithersburg, Maryland 20899-

Enclosed are the samples (Sera 324-328) for the second fat-soluble vitamins and carotenoids in serum 

round robin study (Round Robin LX) for the fiscal year (FY) 06 NIST Micronutrients Measurement 

Quality Assurance Program. You will find one vial of each of three liquid-frozen and two lyophilized 

serum samples for analysis along with a form for reporting your results. When reporting your results, 

please submit one value for each analyte for a given serum sample. If a value is obtained below your 

limit of quantification, please indicate this result on the form by using NQ (Not Quantified). Results are 

due to NIST by September 4, 2006. Results received more than two weeks after the due date will not be 

included in the summary report for this round robin study. The feedback report concerning the study will 

be provided in April. 

Lyophilized samples should be reconstituted with 1.0 mL ofHPLC-grade water or equivalent. We 

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

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

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

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

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

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

is greater than 1.0 mL. Water should not be added to the liquid-frozen samples (Sera 324-326). 

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

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

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

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

Micronutrients Measurement Quality Assurance Program 

NIST 

100 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. ov; or ail/fax queries to the above address. 

e nice Brown omas 

esearch Chemist 

Analytical Chemistry Division 

Chemical Science and Technology Laboratory 

Enclosures 

A2

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Participant #: ________ Date: _____________ 

Round Robin LX: Human Sera 

NIST Micronutrients Measurement Quality Assurance Program 

Analyte 324 325 326 327 328 Units* 

total retinol 

trans-retinol 

didehydroretinol 

retinyl palmitate 

α-tocopherol 

γ/β-tocopherol 

δ-tocopherol 

total β-carotene 

trans-β-carotene 

total cis-β-carotene 

total α-carotene 

total lycopene 

trans-lycopene 

total β-cryptoxanthin 

total α-cryptoxanthin 

total lutein 

total zeaxanthin 

total lutein&zeaxanthin

 total coenzyme Q10 

ubiquinol (QH2) 

ubiquinone (Qox) 

phylloquinone (K1) 

25-hydroxyvitamin D 

Other measurands? 

* we prefer μg/mL 

Were the liquid frozen samples #324, 325, and 326 frozen when received? Yes | No 

Comments: 

Mail: M2QAP 

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

Gaithersburg, MD 20899-8392 4-Sep-2006 Email: David.Duewer@NIST.gov 

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Participant #: ________ Date: _____________ 

Fat-Soluble Vitamins Round Robin LX 

NIST Micronutrients Measurement Quality Assurance Program 

Packing List and Shipment Receipt Confirmation Form 

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

Serum Form Reconstitute? 

#324 Liquid frozen No 

#325 Liquid frozen No 

#326 

#327 

#328 

Liquid frozen 

Lyophilized 

Lyophilized 

No 

Yes (1 ml H2O) 

Yes (1 ml H2O) 

Please 1) Open the pack immediately 

2) Check that it contains all of the above samples 

3) Check if the vials are intact 

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

5) Complete the following information 

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

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

1) Date this shipment arrived: ___________________________ 

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

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

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

4) Did the liquid frozen samples #324, 325, and 326 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 

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Appendix B. Final Report for RR60 

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

•	 Cover letter. 

•	 An information sheet that: 

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

o	 describes the content of the “Individualized” report, 

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

if any, and 

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

participants. 

B1
October 12, 2006 

Dear Colleague: 

UNmD STATES DEPARTMENT OF COMMERCE 

National Institute Df Standard• and Technalagy 

Gaithersburg, Maryland 20899-

Enclosed is the summary report of the results for round robin LX (RR60) of the 2006 NIST 

Micronutrients Measurement Quality Assurance Program (M2

QAP) for the fat-soh. ~le 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. 

Data for evaluating laboratory performance in RR60 are provided in text "Score Card" summary, page 6 

of the All Lab Report. Laboratory comparability is summarized as follows: 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 in the graphical "target plot" summary, last 

page of your Individualized Report. · 

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

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

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

'. 

Samples for the first 2007 QA interlaboratory exercise will be shipped during the week ~f November 

13, 2006. We will send you a reminder via e-mail or fax a week prior to shipment. It is critical that you 

carefully 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. 

Please save the date! We will host the next Micronutrients Measurement Quality Assurance Workshop 

in conjunction with the Experimental Biology meeting on May 2, 2007 at the Convention Center in 

Washington, DC. We will provide you with more details as our plans our finalized. 

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. 

A1tl.e 

nice Brown Thomas 

Research Chemist 

Analytical Chemistry Division 

Chemical Science and Technology Laboratory 

Cc: L.C. Sander 

D.L. Duewer 

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The NIST M2QAP Round Robin LX (RR60) report consists of: 

Page “All Lab” Report 

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

5 A legend for the list of results and statistics. 

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

Page “Individualized” Report 

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

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

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

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

Samples. The five sera below were distributed in RR60. 

Serum
	

324 

325 

326 

327 

328 

Description
	

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

Spring, 2006. 

Fresh-frozen, a 5:7 blend of the Sera 324 and 326 

(i.e., Serum 325 = (5 × Serum324 + 7 × Serum 

326)/12, prepared in Spring, 2006. 

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

Spring, 2006. 

Lyophilized, native, single-donor serum prepared in 

1993. 

Lyophilized, augmented, multi-donor serum 

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. 

Prior Distributions
	

Serum 184:RR28-6/93 

Serum 319:RR59-3/06 

Serum 195:RR31-6/94 

Serum 214:RR35-9/95 

Serum 244:RR43-6/98 

Results 

1)		 Sera Stability. There was no significant change in the median level or variability of any measurand 

in the two lyophilized sera. Both of these materials have been in storage for more than 12 years. 

2)		 Measurand Additivity. Serum 325 was prepared as a mixture of two native, single-donor sera. With 

the exception of α- and β-carotene, the median values in Serum 325 are as expected from the Sera 

324 and 326 medians and their 5:7 blending ratio. For these two measurands, the medians for Serum 

325 are larger than expected. Serum 324 had natively high levels of these two measurands 

(particularly that of α-carotene) while the levels in Serum 326 were fairly low. We will continue to 

investigate whether these departures from expected additive behavior are related to measurand 

lipophilicity. Unfortunately, the retinyl palmitate levels in the Serum 326 material were below many 

participants’ quantification limits; there are insufficient numbers of quantitative values for this 

measurand in both Sera 325 and326 for meaningful statistical assessment. 

B3
 

 

 

 

Appendix C. “All-Lab Report” for RR60 

The following seven 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. 

C1
Round Robin LX Laboratory Results 

All Results in μg/mL 

Total Retinol trans-Retinol Retinyl Palmitate α-Tocopherol 

Lab 324 325 326 327 328 

C2

FSV-BA 0.427 0.341 0.274 0.337 0.357 

FSV-BB 0.474 0.376 0.308 0.378 0.402 

FSV-BC 0.458 0.373 0.296 0.358 0.384 

FSV-BD 0.445 0.379 0.313 0.366 0.360 

FSV-BE 0.502 0.410 0.346 0.399 0.418 

FSV-BF 0.460 0.360 0.280 0.360 0.290 

FSV-BG 0.504 0.390 0.307 0.366 0.416 

FSV-BH 0.378 0.314 0.233 0.289 0.346 

FSV-BI 0.417 0.345 0.283 0.344 0.361 

FSV-BJ 0.447 0.353 0.276 0.347 0.385 

FSV-BK 0.540 0.410 0.330 0.410 0.420 

FSV-BL 0.460 0.370 0.320 0.340 0.230 

FSV-BM 0.468 0.379 0.330 0.369 0.380 

FSV-BN 0.430 0.377 0.322 0.388 0.423 

FSV-BO 0.400 0.350 0.300 0.320 0.290 

FSV-BP 0.462 0.388 0.323 0.390 0.419 

FSV-BQ 0.601 0.496 0.446 0.457 0.475 

FSV-BR ≥0.503 ≥0.393 ≥0.310 ≥0.409 ≥0.429

FSV-BS ≥0.530 ≥0.424 ≥0.355 ≥0.422 ≥0.461

FSV-BT 0.472 0.384 0.391 0.320 0.357 

FSV-BU 0.468 0.368 0.303 0.367 0.315 

FSV-BV 0.410 0.340 0.315 0.383 0.237 

FSV-BW 0.410 0.310 0.260 0.310 0.330 

FSV-CC 0.470 0.390 0.310 0.370 0.410 

FSV-CD ≥0.400 ≥0.350 ≥0.260 ≥0.320 ≥0.300

FSV-CE 0.431 0.371 0.310 0.357 0.386 

FSV-CF 0.494 0.388 0.314 0.396 0.453 

FSV-CG 0.463 0.363 0.304 0.368 0.400 

FSV-CI 0.413 0.339 0.275 0.309 0.273 

FSV-CP 

FSV-CS 0.460 0.370 0.382 0.396 0.285 

FSV-CT 

FSV-CW 0.353 0.331 0.273 0.381 0.453 

FSV-CZ 0.478 0.380 0.307 0.374 0.395 

FSV-DB 0.498 0.372 0.335 0.375 0.412 

FSV-DF 0.500 0.391 0.326 0.397 0.417 

FSV-DI 0.429 0.360 0.296 0.357 0.380 

FSV-DQ 

FSV-DV ≥0.544 ≥0.422 ≥0.359 ≥0.429 ≥0.466

324 325 326 327 328 

0.503 0.393 0.310 0.409 0.429 

0.530 0.424 0.355 0.422 0.461 

0.460 0.370 0.310 

0.400 0.350 0.260 

0.544 0.422 0.359 0.429 0.466 

0.370 0.380 

0.320 0.300 

324 325 326 327 328 

0.057 0.055 0.063 0.127 0.081 

0.055 0.027 0.059 0.128 0.085 

0.060 0.058 0.053 0.098 0.053 

0.082 nd nd 0.160 0.126 

0.050 0.026 nq 0.139 0.129 

0.049 0.032 0.021 0.103 0.126 

0.080 0.050 0.020 0.130 0.170 

4.220 7.900 11.110 1.170 0.490 

0.047 0.019 nd 0.148 0.103 

0.033 0.023 0.016 0.092 0.109 

0.048 0.024 0.010 0.194 0.129 

324 325 326 327 328 

9.40 8.70 7.62 4.27 5.8

10.19 9.40 8.58 4.50 6.0

9.30 9.30 8.00 4.30 7.1

9.94 8.90 8.36 4.36 6.5

10.50 9.40 8.70 4.70 6.1

10.79 9.59 8.50 4.16 6.7

9.31 8.20 7.97 4.21 6.6

10.55 9.51 8.77 4.68 7.2

10.03 9.13 7.96 4.19 7.4

11.34 10.03 8.96 4.96 6.7

9.50 10.80 11.20 6.00 6.5

10.20 9.20 8.80 4.50 6.5

8.93 8.37 7.97 4.19 6.3

7.43 4.04 1.08 3.68 5.5

8.67 8.17 7.53 4.10 8.6

8.61 7.82 7.74 3.91 6.5

9.67 8.81 8.30 4.03 6.5

11.03 9.04 8.06 4.43 6.7

11.12 9.72 8.23 4.94 7.2

9.86 8.59 7.78 4.30 6.7

9.18 8.85 8.35 4.33 6.7

9.59 8.36 7.84 4.01 6.1

9.65 8.76 8.33 4.06 6.4

8.32 8.34 7.68 3.74 5.4

11.13 9.44 8.47 4.54 6.6

11.80 10.60 9.60 5.20 8.6

9.39 8.51 7.65 3.99 6.2

9.59 8.51 8.18 4.42 7.0

11.22 10.46 8.95 5.02 7.2

10.24 11.52 8.79 7.89 5.8

10.50 9.51 9.31 4.27 7.0

10.10 9.10 8.40 4.50 7.5

11.35 9.51 8.93 4.74 7.2

9.48 8.68 8.24 4.12 6.3

9.85 8.50 5.29 4.24 6.1

10.40 9.10 8.60 4.40 6.6

N 32 32 32 32 32 5 5 5 5 5 11 10 8 11 11 36 36 36 36 3

Min 0.353 0.310 0.233 0.289 0.230 0.400 0.350 0.260 0.320 0.300 0.033 0.019 0.010 0.092 0.053 7.43 4.04 1.08 3.68 5.4

Median 0.460 0.372 0.309 0.367 0.385 0.503 0.393 0.310 0.409 0.429 0.055 0.030 0.037 0.130 0.126 9.90 9.07 8.32 4.32 6.6

Max 0.601 0.496 0.446 0.457 0.475 0.544 0.424 0.359 0.429 0.466 4.220 7.900 11.110 1.170 0.490 11.80 11.52 11.20 7.89 8.6

eSD 0.035 0.024 0.023 0.028 0.055 0.016 0.022 0.030 0.029 0.026 0.83 0.74 0.58 0.32 0.5

eCV 8 7 7 8 14 0 0 0 0 0 29 74 82 22 21 8 8 7 7 

Npast 0 0 0 39 44 0 0 0 0 0 0 0 0 9 10 0 0 0 40 4

Medianpast 0.365 0.380 0.124 0.111 4.333 7.18

SDpast 0.029 0.037 0.029 0.025 0.277 0.74

NAV 0.460 0.372 0.309 0.367 0.385 0.503 0.393 0.310 0.409 0.429 0.055 0.030 0.037 0.130 0.126 9.900 9.071 8.315 4.315 6.61

NAU 0.037 0.030 0.026 0.030 0.055 0.040 0.032 0.026 0.033 0.035 0.017 0.022 0.030 0.032 0.032 0.829 0.742 0.666 0.449 0.56

All Lab Report 
Round Robin LX Laboratory Results 

All Results in μg/mL 

δ-Tocopherol Total β-Carotene trans-β-Carotene Total cis-β-Carotene 

Lab 324 325 326 327 328 

C3

FSV-BA 0.127 0.096 0.076 0.044 0.077 

FSV-BB 0.115 0.092 0.074 0.035 0.071 

FSV-BC 

FSV-BD 

FSV-BE 

FSV-BF 

FSV-BG 

FSV-BH 0.141 0.096 0.076 0.081 0.070 

FSV-BI 

FSV-BJ 

FSV-BK 

FSV-BL 

FSV-BM 

FSV-BN nd nd nd nd nd 

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 0.135 nd nd nd nd 

FSV-CI 

FSV-CP 

FSV-CS 

FSV-CT 

FSV-CW 0.158 0.112 0.097 0.050 0.081 

FSV-CZ 

FSV-DB 0.230 0.170 nq nq 0.140 

FSV-DF 

FSV-DI 0.110 0.090 0.076 0.046 0.064 

FSV-DQ 

FSV-DV 

324 325 326 327 328 

0.501 0.307 0.160 0.320 0.327 

0.427 0.236 0.112 0.304 0.280 

0.494 0.228 0.131 0.284 0.319 

0.483 0.288 0.136 0.334 0.469 

0.512 0.312 0.148 0.352 0.331 

0.533 0.296 0.144 0.328 0.336 

0.497 0.296 0.140 0.298 0.334 

0.506 0.296 0.135 0.312 0.397 

0.402 0.249 0.131 0.270 0.294 

0.536 0.161 0.597 !0.115 0.121 

0.545 0.532 0.093 

0.501 0.270 0.162 

0.506 0.296 0.149 

0.481 0.287 0.157 

0.477 0.290 0.148 

0.590 0.350 0.190 

nq 0.610 0.340 

0.548 0.307 0.160 

0.484 0.277 0.135 

≥0.497 ≥0.246 ≥0.123 ≥0.296

0.484 0.289 0.146 

0.524 0.279 0.131 0.347 0.374 

0.560 0.332 0.172 0.369 0.401 

≥0.424 ≥0.282 ≥0.122 ≥0.361 ≥0.411

0.532 0.327 0.152 0.281 0.312 

0.538 0.293 0.136 0.307 0.345 

0.488 0.307 0.189 0.306 0.329 

0.381 0.310 0.131 0.297 0.294 

0.155 0.609 

0.343 0.315 

0.337 0.388 

0.306 0.304 

0.321 0.355 

0.420 0.420 

0.690 0.430 

0.307 0.289 

0.297 0.319 

≥0.303

0.288 0.311 

324 325 326 327 328 

0.463 0.282 0.143 0.293 0.301 

0.403 0.225 0.106 0.284 0.258 

0.506 0.282 0.144 0.308 0.312 

0.370 0.231 0.123 0.248 0.261 

0.478 0.281 0.141 0.316 0.360 

0.456 0.261 0.128 0.279 0.293 

0.497 0.246 0.123 0.296 0.303 

0.424 0.282 0.122 0.361 0.411 

324 325 326 327 328 

0.038 0.026 0.017 0.027 0.026 

0.025 0.011 0.005 0.020 0.022 

0.027 0.014 nq 0.020 0.024 

0.038 0.025 0.015 0.028 0.039 

0.031 0.017 0.009 0.021 0.029 

0.028 0.016 0.007 0.018 0.025 

N 7 6 5 5 6 25 26 26 25 26 8 8 8 8 8 6 6 5 6 6 

Min 0.110 0.090 0.074 0.035 0.064 0.381 0.161 0.093 0.155 0.121 0.370 0.225 0.106 0.248 0.258 0.025 0.011 0.005 0.018 0.022 

Median 0.135 0.096 0.076 0.046 0.074 0.501 0.296 0.147 0.307 0.330 0.460 0.271 0.126 0.295 0.302 0.030 0.017 0.009 0.021 0.026 

Max 0.230 0.170 0.097 0.081 0.140 0.590 0.610 0.597 0.690 0.609 0.506 0.282 0.144 0.361 0.411 0.038 0.026 0.017 0.028 0.039 

eSD 0.021 0.011 0.004 0.004 0.007 0.036 0.021 0.019 0.030 0.054 0.048 0.029 0.014 0.020 0.029 0.007 0.006 0.006 0.004 0.003 

eCV 16 12 5 10 10 7 7 13 10 17 10 11 11 7 10 23 38 66 20 12 

Npast 0 0 0 6 0 0 0 0 29 32 0 0 0 7 10 0 0 0 5 8 

Medianpast 0.049 0.338 0.345 0.306 0.326 0.021 0.027 

SDpast 0.009 0.047 0.038 0.028 0.028 0.008 0.013 

NAV 0.135 0.096 0.076 0.046 0.074 0.501 0.296 0.147 0.307 0.330 0.460 0.271 0.126 0.295 0.302 0.030 0.017 0.009 0.021 0.026 

NAU 0.028 0.023 0.021 0.017 0.020 0.070 0.043 0.023 0.045 0.054 0.048 0.029 0.015 0.032 0.032 0.011 0.006 0.006 0.007 0.009 

All Lab Report 
Round Robin LX Laboratory Results 

All Results in μg/mL 

Total Lycopene trans-Lycopene Total β-Cryptoxanthin Total α-Cryptoxanthin 

Lab 324 325 326 327 328 

C4

FSV-BA 0.340 0.477 0.562 0.186 0.077 

FSV-BB 0.308 0.405 0.456 0.191 0.091 

FSV-BC 

FSV-BD 

FSV-BE 

FSV-BF 0.366 0.544 0.659 0.185 0.086 

FSV-BG 0.362 0.519 0.602 0.206 0.081 

FSV-BH 0.399 0.533 0.659 0.224 0.081 

FSV-BI 0.286 0.401 0.569 0.157 0.058 

FSV-BJ 0.400 0.544 0.589 0.210 0.106 

FSV-BK 

FSV-BL 

FSV-BM 

FSV-BN 0.288 0.402 0.516 0.169 0.073 

FSV-BO 0.346 0.529 0.693 !0.0123 0.102 

FSV-BP 0.215 0.408 0.585 0.154 0.137 

FSV-BQ 

FSV-BR 

FSV-BS 0.375 0.454 0.659 0.200 0.072 

FSV-BT 0.431 0.578 0.685 0.237 0.125 

FSV-BU 0.351 0.480 0.585 0.187 0.083 

FSV-BV 0.358 0.500 0.580 0.190 0.075 

FSV-BW 0.340 0.490 0.610 0.190 0.070 

FSV-CC 

FSV-CD nq 0.080 nq 0.030 0.010 

FSV-CE 

FSV-CF 

FSV-CG 0.366 0.483 0.579 0.192 0.074 

FSV-CI 

FSV-CP 0.211 0.309 0.377 0.117 0.040 

FSV-CS 0.340 0.449 0.505 0.183 0.088 

FSV-CT 0.324 0.485 0.602 0.213 0.085 

FSV-CW 

FSV-CZ 

FSV-DB 0.361 0.494 0.585 0.199 0.079 

FSV-DF 

FSV-DI 0.377 0.504 0.590 0.202 0.061 

FSV-DQ 0.349 0.628 0.697 0.136 0.002 

FSV-DV 

324 325 326 327 328 

0.168 0.254 0.306 0.105 0.034 

0.139 0.191 0.226 0.089 0.024 

0.185 0.282 0.335 0.116 0.034 

0.138 0.211 0.271 0.090 0.034 

0.188 0.258 0.307 0.108 

0.171 0.249 0.310 0.105 

0.087 0.173 0.213 0.070 0.007 

0.047 

0.033 

324 325 326 327 328 

0.080 0.123 0.142 0.073 0.012 

0.059 0.085 0.103 0.056 0.010 

0.057 0.095 0.120 0.055 0.008 

0.050 0.074 0.092 0.051 0.009 

0.074 0.102 0.126 0.061 nq 

0.056 0.092 0.112 0.056 0.010 

0.048 0.075 0.087 0.045 nq 

0.054 0.086 0.114 0.058 0.013 

0.047 0.074 0.103 !0.2165 0.010 

0.057 0.088 0.106 0.054 0.030 

0.060 0.093 0.137 0.053 0.003 

0.062 0.088 0.116 0.061 0.013 

0.053 0.074 0.088 0.051 0.028 

0.040 0.063 0.080 0.038 0.005 

0.080 0.125 0.177 0.077 0.006 

nq 0.210 0.340 0.120 nq 

0.080 0.113 0.141 0.070 0.013 

0.071 0.116 0.146 0.075 0.011 

0.074 0.089 0.090 0.054 0.008 

0.051 0.079 0.098 0.050 0.011 

0.048 0.076 0.090 0.053 0.017 

0.072 0.093 0.114 0.063 nq 

0.045 0.079 0.101 0.056 nd 

324 325 326 327 328 

0.033 0.050 0.058 0.038 0.006 

0.023 0.030 0.036 0.028 0.003 

0.017 0.029 0.040 0.025 0.006 

0.022 0.031 0.040 0.022 0.008 

0

0

0

0

0

0

0

0

0

0

0

0

0

N 22 23 22 22 23 7 7 7 7 7 22 23 23 22 18 4 4 4 4 4 

Min 0.211 0.080 0.377 0.030 0.002 0.087 0.173 0.213 0.070 0.007 0.040 0.063 0.080 0.038 0.003 0.017 0.029 0.036 0.022 0.003 0

Median 0.350 0.485 0.587 0.190 0.079 0.168 0.249 0.306 0.105 0.034 0.057 0.088 0.112 0.056 0.011 0.023 0.031 0.040 0.027 0.006 0

Max 0.431 0.628 0.697 0.237 0.137 0.188 0.282 0.335 0.116 0.047 0.080 0.210 0.340 0.120 0.030 0.033 0.050 0.058 0.038 0.008 0

eSD 0.028 0.071 0.056 0.021 0.012 0.029 0.041 0.045 0.013 0.004 0.016 0.015 0.027 0.007 0.004 0.004 0.004 0.004 0.005 0.001 0

eCV 8 15 9 11 15 17 16 15 12 12 28 18 24 13 34 16 15 10 18 15 

Npast 0 0 0 19 24 0 0 0 7 8 0 0 0 16 17 0 0 0 4 7 

Medianpast 0.185 0.068 0.094 0.041 0.060 0.012 0.025 0.007 

SDpast 0.035 0.023 0.013 0.009 0.009 0.005 0.006 0.002 

NAV 0.350 0.485 0.587 0.190 0.079 0.168 0.249 0.306 0.105 0.034 0.057 0.088 0.112 0.056 0.011 0.023 0.031 0.040 0.027 0.006 0

NAU 0.077 0.101 0.118 0.047 0.023 0.030 0.045 0.056 0.018 0.008 0.016 0.020 0.027 0.013 0.004 0

All Lab Report 
Round Robin LX Laboratory Results 

All Results in μg/mL 

Total Zeaxanthin Total Lutein&Zeaxanthin Coenzyme Q10 Ubiquinol 

Lab 324 325 326 327 328 

C5

FSV-BA 

FSV-BB 0.025 0.057 0.075 0.025 0.015 

FSV-BC 

FSV-BD 

FSV-BE 

FSV-BF 

FSV-BG 0.044 0.033 0.027 0.024 0.009 

FSV-BH 0.012 0.050 0.077 0.024 0.007 

FSV-BI 

FSV-BJ 

FSV-BK 

FSV-BL 

FSV-BM 

FSV-BN 0.007 0.054 0.085 0.019 0.004 

FSV-BO 0.011 0.034 0.054 !0.017 nd 

FSV-BP 

FSV-BQ 

FSV-BR 

FSV-BS 

FSV-BT 0.036 0.045 0.067 0.020 0.011 

FSV-BU 

FSV-BV 

FSV-BW 

FSV-CC 

FSV-CD 

FSV-CE 

FSV-CF 

FSV-CG 

FSV-CI 0.018 0.041 0.057 0.019 <0.006 

FSV-CP 

FSV-CS 0.014 0.042 0.055 0.027 0.006 

FSV-CT 0.009 0.029 0.047 0.016 0.007 

FSV-CW 0.022 0.037 0.049 0.021 0.016 

FSV-CZ 

FSV-DB 

FSV-DF 

FSV-DI 

FSV-DQ 0.029 0.058 0.080 0.022 0.009 

FSV-DV 

324 325 326 327 328 

0.137 0.173 0.194 0.092 0.034 

0.152 0.193 0.229 0.121 0.052 

0.153 0.182 0.197 0.098 0.034 

0.198 0.152 0.106 0.087 0.034 

0.117 0.158 0.188 0.092 0.025 

0.180 0.221 0.249 0.112 0.037 

0.113 0.171 0.212 0.090 0.034 

0.138 0.169 0.206 !0.0951 0.027 

0.061 0.093 0.107 0.032 0.040 

0.018 0.134 0.171 

0.143 0.189 0.275 

0.146 0.188 0.210 

0.165 0.206 0.250 

0.170 0.220 0.290 

0.192 0.242 0.283 

0.133 0.164 0.189 

0.237 0.298 0.333 

0.130 0.174 0.192 0.111 0.038 

0.176 0.237 0.271 0.182 0.045 

0.133 0.170 0.187 0.112 0.054 

0.149 0.188 0.233 0.092 0.031 

0.210 0.244 0.305 0.146 0.025 

0.069 0.025 

0.092 0.037 

0.090 0.039 

0.109 0.035 

0.132 0.038 

0.120 0.043 

0.096 >0.023 

0.149 0.050 

324 325 326 327 328 

0.788 1.115 1.292 0.750 0.340 

0.590 0.850 1.190 0.890 0.350 

0.779 0.913 1.007 0.653 0.403 

0.770 1.020 1.170 0.740 0.360 

0.684 0.986 1.210 0.702 0.299 

324 325 326 327 328 

0.140 0.150 0.830 0.780 0.2

0.051 0.522 1.042 0.658 0.1

N 11 11 11 10 9 22 22 22 21 21 5 5 5 5 5 2 2 2 2 

Min 0.007 0.029 0.027 0.016 0.004 0.018 0.093 0.106 0.032 0.025 0.590 0.850 1.007 0.653 0.299 0.051 0.150 0.830 0.658 0.1

Median 0.018 0.042 0.057 0.022 0.009 0.148 0.185 0.211 0.098 0.037 0.770 0.986 1.190 0.740 0.350 0.096 0.336 0.936 0.719 0.1

Max 0.044 0.058 0.085 0.027 0.016 0.237 0.298 0.333 0.182 0.054 0.788 1.115 1.292 0.890 0.403 0.140 0.522 1.042 0.780 0.2

eSD 0.012 0.012 0.018 0.004 0.003 0.031 0.035 0.056 0.021 0.004 0.070 0.079 0.060 0.037 0.018 

eCV 65 29 32 16 33 21 19 27 22 12 9 8 5 5 5 

Npast 0 0 0 15 8 0 0 0 15 18 0 0 0 5 0 0 0 0 0 

Medianpast 0.023 0.011 0.110 0.040 0.694 

SDpast 0.005 0.006 0.016 0.009 0.084 

NAV 0.018 0.042 0.057 0.022 0.009 0.148 0.185 0.211 0.098 0.037 0.770 0.986 1.190 0.740 0.350 

NAU 0.012 0.012 0.018 0.006 0.004 0.031 0.039 0.056 0.021 0.008 0.077 0.099 0.119 0.074 0.035 

All Lab Report 
Round Robin LX Laboratory Results 

All Results in μg/mL 

Phylloquinone (K1) x1000 25-hydroxyvitamin D 

Lab 324 325 326 327 328 

C6

FSV-BA 

FSV-BB 

FSV-BC 

FSV-BD 

FSV-BE 2.608 1.466 0.593 0.212 0.656 

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 1.890 1.110 0.520 0.230 0.510 

FSV-CP 

FSV-CS 

FSV-CT 

FSV-CW 

FSV-CZ 

FSV-DB 

FSV-DF 

FSV-DI 1.280 0.800 0.170 <0.05 0.410 

FSV-DQ 

FSV-DV 

324 325 326 327 328 

0.0125 0.0093 0.0067 0.0048 0.0120 

0.0180 0.0120 0.0080 0.0050 0.0120 

0.0154 0.0095 0.0077 0.0025 0.0221 

N 3 3 3 2 3 3 3 3 3 3 

Min 1.28 0.80 0.17 0.21 0.41 0.0125 0.0093 0.0067 0.0025 0.0120 

Median 1.89 1.11 0.52 0.22 0.51 0.0154 0.0095 0.0077 0.0048 0.0120 

Max 2.61 1.47 0.59 0.23 0.66 0.0180 0.0120 0.0080 0.0050 0.0221 

eSD 

eCV 

Npast 0 0 0 0 0 0 0 0 4 0 

Medianpast 0.0042 

SDpast 0.0004 

NAV 1.890 1.110 0.520 0.510 0.0154 0.0095 0.0077 0.0048 0.0120 

NAU 

All Lab Report 
 

 

 

 

Term 

N

Min

Medianpart

Max

eSD

eCV

Npast

Medianpast

SDpast

NAV

NAU

nd

nq

≥x

!

italics

Round Robin LX Laboratory Results 

Legend 

Definition 

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

 Minimum (non-NIST) quantitative value reported 

 Median (non-NIST) quantitative value reported 

 Maximum (non-NIST) quantitative value reported 

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

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

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

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

 Pooled SD from past RR(s) 

 NIST Assigned Value

 NAV is the Medianpart for analytes reported by ≥ 5 labs. 

 NIST Assigned Uncertainty

 NAU is the maximum of (0.05*NAV, SD, eSD) where eSD is the expected

 long-term SD and 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 

 Non-quantitative value: heterogeneous serum, damaged sample, malfunction, etc. 

 Not explictly reported but calculated by NIST from reported values 

All Lab Report Page 6 / 7 

C7
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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-CP 

FSV-CS 

FSV-CT 

FSV-CW 

FSV-CZ 

FSV-DB 

FSV-DF 

FSV-DI 

FSV-DQ 

FSV-DV 

n 

% 1 

% 2 

% 3 

% 4 

Round Robin LX Laboratory Results 

Comparability Summary 

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

2 1 1 1 1 2 1 2 1 

1 1 1 2 2 1 1 1 1 2 2 

1 

1 1 

2 1 1 1 

1 1 1 2 1 1 1 1 

1 1 1 1 1 1 1 2 2 2 

3 1 1 1 1 1 1 1 2 1 1 

1 1 2 1 1 1 1 1 

1 1 1 1 1 1 1 1 

2 2 

2 3 

1 1 

1 1 2 1 2 1 1 1 1 2 1 

2 4 4 4 1 1 1 1 1 1 

1 3 4 3 2 3 3 

4 2 

1 1 

2 1 1 1 1 1 2 3 

2 2 1 1 2 1 2 1 1 1 1 

1 1 1 1 1 1 3 1 

2 1 1 1 1 1 2 1 

2 1 4 2 3 1 2 2 

1 1 

2 2 2 4 2 4 4 4 

1 1 1 

1 3 

1 1 1 1 1 1 1 2 2 

2 1 1 1 1 1 1 1 1 

2 2 1 1 2 2 3 

2 4 4 1 1 1 1 1 1 1 

2 1 1 3 1 3 

2 1 2 2 2 1 2 1 2 2 

1 1 1 

1 2 1 1 1 1 1 

1 

1 1 1 1 1 1 

3 1 1 1 2 1 3 1 2 

2 1 

36 36 24 28 8 22 23 23 14 11 22 

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

56 67 67 71 50 82 78 57 64 64 55 

39 17 21 18 50 9 17 30 14 36 27 

3 11 0 0 0 9 0 9 14 0 18 

3 6 13 11 0 0 4 4 7 0 0 

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 7 / 7 

C8
 

 

 

 

 

Appendix D. Representative “Individualized Report” for RR60 

Each participant in RR60 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 RR60: 

• Total Retinol 

• trans-Retinol 

• Retinyl Palmitate 

• α-Tocopherol 

• γ/β-Tocopherol 

• δ-Tocopherol 

• Total β-Carotene 

• trans-β-Carotene 

• Total cis-β-Carotene 

• Total α-Carotene 

• Total Lycopene 

• trans-Lycopene 

• Total β-Cryptoxanthin 

• Total Lutein 

• Total Zeaxanthin 

• Total Lutein & Zeaxanthin 

• Coenzyme Q10 

The following 14 pages are the “Individualized Report” for the analytes evaluated by 

participant FSV-BA. 

D1
 

Set 1 of 39 

Individualized Round Robin LX Report: FSV-BA 

Summary 

Serum 324 Serum 325 Serum 326 Serum 327 

D2

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

Total Retinol 0.427 0.460 32 0.341 0.372 32 0.274 0.309 32 0.337 0.367 32 

Retinyl Palmitate 0.06 0.06 11 0.1 0.0 10 0.1 0.0 8 0.13 0.13 11 

α-Tocopherol 9.40 9.90 36 8.70 9.07 36 7.62 8.32 36 4.27 4.32 36 

γ/β-Tocopherol 2.493 2.585 24 3.093 3.164 24 3.401 3.624 24 1.570 1.662 24 

δ-Tocopherol 0.127 0.135 7 0.096 0.096 6 0.076 0.076 5 0.044 0.046 5 

Total β-Carotene 0.501 0.501 25 0.307 0.296 26 0.160 0.147 26 0.320 0.307 25 

trans-β-Carotene 0.463 0.460 8 0.282 0.271 8 0.143 0.126 8 0.293 0.295 8 

Total cis-β-Carotene 0.038 0.030 6 0.026 0.017 6 0.017 0.009 5 0.027 0.021 6 

Total α-Carotene 0.277 0.277 21 0.132 0.129 22 0.024 0.017 19 0.028 0.017 18 

Total Lycopene 0.340 0.350 22 0.477 0.485 23 0.562 0.587 22 0.186 0.190 22 

trans-Lycopene 0.168 0.168 7 0.254 0.249 7 0.306 0.306 7 0.105 0.105 7 

Total β-Cryptoxanthin 0.080 0.057 22 0.123 0.088 23 0.142 0.112 23 0.073 0.056 22 

Total α-Cryptoxanthin 0.033 0.023 4 0.050 0.031 4 0.058 0.040 4 0.038 0.027 4 

Total Lutein&Zeaxanthin 0.137 0.148 22 0.173 0.185 22 0.194 0.211 22 0.092 0.098 21 

25-hydroxyvitamin D 0.013 0.015 3 0.009 0.010 3 0.007 0.008 3 0.005 0.005 3 

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

Individualized Report 
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.

NIST, this RR

 

Set 1 of 39 

Individualized RR LX Report: FSV-BA 

Total Retinol 

Apparent Precision, SD [Analyte], μg/mL

324325326184319327195214244328

Your [Analyte], μg/mL

Apparent Precision, SD 

Median [Analyte], μg/mL 

Long-term Precision, SD Concordance, SD 

3rd Quartile (75%) 

You, this RR You, ≥x, this RR

Median (50%) 

You, past RRs You, ≥x, past RRs Others, this RR 1st Quartile (25%) 

Serum History Comments 

#324 Fresh frozen Native, single-source 

#325 Fresh frozen 25:35 blend of #324 and #326 

#326 Fresh frozen Native, single-source 

#327 Lyophilized - 28:184, 59:319 Native, single-source 

#328 Lyophilized - 31:195, 35:214, 43:244 Manipulated, multi-source 

Individualized Report Page 2 / 14 

D3
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.

NIST, this RR

 

Set 1 of 39 

Individualized RR LX Report: FSV-BA 

Retinyl Palmitate 

[Analyte], μg/mL

Your [Analyte], μg/mL

Median [Analyte], μg/mL 

Apparent Precision, SD 

324325326184319327195214244328 

Apparent Precision, SD 

Long-term Precision, SD Concordance, SD 

3rd Quartile (75%) 

You, this RR You, ≥x, this RR

Median (50%) 

You, past RRs You, ≥x, past RRs Others, this RR 1st Quartile (25%) 

Serum History Comments 

#324 Fresh frozen Native, single-source 

#325 Fresh frozen 25:35 blend of #324 and #326 

#326 Fresh frozen Native, single-source 

#327 Lyophilized - 28:184, 59:319 Native, single-source 

#328 Lyophilized - 31:195, 35:214, 43:244 Manipulated, multi-source 

Individualized Report Page 3 / 14 

D4
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.

NIST, this RR

 

Set 1 of 39 

Individualized RR LX Report: FSV-BA 

α-Tocopherol 

[Analyte], μg/mL

Your [Analyte], μg/mL

Median [Analyte], μg/mL 

Apparent Precision, SD 

324325326184319327195214244328 

Apparent Precision, SD 

Long-term Precision, SD Concordance, SD 

3rd Quartile (75%) 

You, this RR You, ≥x, this RR

Median (50%) 

You, past RRs You, ≥x, past RRs Others, this RR 1st Quartile (25%) 

Serum History Comments 

#324 Fresh frozen Native, single-source 

#325 Fresh frozen 25:35 blend of #324 and #326 

#326 Fresh frozen Native, single-source 

#327 Lyophilized - 28:184, 59:319 Native, single-source 

#328 Lyophilized - 31:195, 35:214, 43:244 Manipulated, multi-source 

Individualized Report Page 4 / 14 

D5
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.

NIST, this RR

 

Set 1 of 39 

Individualized RR LX Report: FSV-BA 

γ/β-Tocopherol 

[Analyte], μg/mL

Your [Analyte], μg/mL

Median [Analyte], μg/mL 

Apparent Precision, SD 

324325326184319327195214244328 

Apparent Precision, SD 

Long-term Precision, SD Concordance, SD 

3rd Quartile (75%) 

You, this RR You, ≥x, this RR

Median (50%) 

You, past RRs You, ≥x, past RRs Others, this RR 1st Quartile (25%) 

Serum History Comments 

#324 Fresh frozen Native, single-source 

#325 Fresh frozen 25:35 blend of #324 and #326 

#326 Fresh frozen Native, single-source 

#327 Lyophilized - 28:184, 59:319 Native, single-source 

#328 Lyophilized - 31:195, 35:214, 43:244 Manipulated, multi-source 

Individualized Report Page 5 / 14 

D6
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.

NIST, this RR

 

Set 1 of 39 

Individualized RR LX Report: FSV-BA 

δ-Tocopherol 

[Analyte], μg/mL

Your [Analyte], μg/mL

Median [Analyte], μg/mL 

324325326184319327195214244328 

Apparent Precision, SD 

Concordance, SD 

Apparent Precision, SD 

Long-term Precision, SD 

3rd Quartile (75%) 

You, this RR You, ≥x, this RR

Median (50%) 

You, past RRs You, ≥x, past RRs Others, this RR 1st Quartile (25%) 

Serum History Comments 

#324 Fresh frozen Native, single-source 

#325 Fresh frozen 25:35 blend of #324 and #326 

#326 Fresh frozen Native, single-source 

#327 Lyophilized - 28:184, 59:319 Native, single-source 

#328 Lyophilized - 31:195, 35:214, 43:244 Manipulated, multi-source 

Individualized Report Page 6 / 14 

D7
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.

NIST, this RR

 

Set 1 of 39 

Individualized RR LX Report: FSV-BA 

Total β-Carotene 

[Analyte], μg/mL

Your [Analyte], μg/mL

Median [Analyte], μg/mL 

Apparent Precision, SD 

324325326184319327195214244328 

Apparent Precision, SD 

Long-term Precision, SD Concordance, SD 

3rd Quartile (75%) 

You, this RR You, ≥x, this RR

Median (50%) 

You, past RRs You, ≥x, past RRs Others, this RR 1st Quartile (25%) 

Serum History Comments 

#324 Fresh frozen Native, single-source 

#325 Fresh frozen 25:35 blend of #324 and #326 

#326 Fresh frozen Native, single-source 

#327 Lyophilized - 28:184, 59:319 Native, single-source 

#328 Lyophilized - 31:195, 35:214, 43:244 Manipulated, multi-source 

Individualized Report Page 7 / 14 

D8
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.

NIST, this RR

 

Set 1 of 39 

Individualized RR LX Report: FSV-BA 

trans-β-Carotene 

[Analyte], μg/mL

Your [Analyte], μg/mL

Median [Analyte], μg/mL 

Apparent Precision, SD 

324325326184319327195214244328 

Apparent Precision, SD 

Long-term Precision, SD Concordance, SD 

3rd Quartile (75%) 

You, this RR You, ≥x, this RR

Median (50%) 

You, past RRs You, ≥x, past RRs Others, this RR 1st Quartile (25%) 

Serum History Comments 

#324 Fresh frozen Native, single-source 

#325 Fresh frozen 25:35 blend of #324 and #326 

#326 Fresh frozen Native, single-source 

#327 Lyophilized - 28:184, 59:319 Native, single-source 

#328 Lyophilized - 31:195, 35:214, 43:244 Manipulated, multi-source 

Individualized Report Page 8 / 14 

D9
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.

NIST, this RR

 

Set 1 of 39 

Individualized RR LX Report: FSV-BA 

Total α-Carotene 

[Analyte], μg/mL

Your [Analyte], μg/mL

Median [Analyte], μg/mL 

Apparent Precision, SD 

324325326184319327195214244328 

Apparent Precision, SD 

Long-term Precision, SD Concordance, SD 

3rd Quartile (75%) 

You, this RR You, ≥x, this RR

Median (50%) 

You, past RRs You, ≥x, past RRs Others, this RR 1st Quartile (25%) 

Serum History Comments 

#324 Fresh frozen Native, single-source 

#325 Fresh frozen 25:35 blend of #324 and #326 

#326 Fresh frozen Native, single-source 

#327 Lyophilized - 28:184, 59:319 Native, single-source 

#328 Lyophilized - 31:195, 35:214, 43:244 Manipulated, multi-source 

Individualized Report Page 9 / 14 

D10
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.

NIST, this RR

 

Set 1 of 39 

Individualized RR LX Report: FSV-BA 

Total Lycopene 

[Analyte], μg/mL

Your [Analyte], μg/mL

Median [Analyte], μg/mL 

324325326184319327195214244328 

Apparent Precision, SD 

Concordance, SD 

Apparent Precision, SD 

Long-term Precision, SD 

3rd Quartile (75%) 

You, this RR You, ≥x, this RR

Median (50%) 

You, past RRs You, ≥x, past RRs Others, this RR 1st Quartile (25%) 

Serum History Comments 

#324 Fresh frozen Native, single-source 

#325 Fresh frozen 25:35 blend of #324 and #326 

#326 Fresh frozen Native, single-source 

#327 Lyophilized - 28:184, 59:319 Native, single-source 

#328 Lyophilized - 31:195, 35:214, 43:244 Manipulated, multi-source 

Individualized Report Page 10 / 14 

D11
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.

NIST, this RR

 

Set 1 of 39 

Individualized RR LX Report: FSV-BA 

trans-Lycopene 

[Analyte], μg/mL

Your [Analyte], μg/mL

Median [Analyte], μg/mL 

Apparent Precision, SD 

324325326184319327195214244328 

Apparent Precision, SD 

Long-term Precision, SD Concordance, SD 

3rd Quartile (75%) 

You, this RR You, ≥x, this RR

Median (50%) 

You, past RRs You, ≥x, past RRs Others, this RR 1st Quartile (25%) 

Serum History Comments 

#324 Fresh frozen Native, single-source 

#325 Fresh frozen 25:35 blend of #324 and #326 

#326 Fresh frozen Native, single-source 

#327 Lyophilized - 28:184, 59:319 Native, single-source 

#328 Lyophilized - 31:195, 35:214, 43:244 Manipulated, multi-source 

Individualized Report Page 11 / 14 

D12
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.

NIST, this RR

 

Set 1 of 39 

Individualized RR LX Report: FSV-BA 

Total β-Cryptoxanthin 

[Analyte], μg/mL

Your [Analyte], μg/mL

Median [Analyte], μg/mL 

Apparent Precision, SD 

324325326184319327195214244328 

Apparent Precision, SD 

Long-term Precision, SD Concordance, SD 

3rd Quartile (75%) 

You, this RR You, ≥x, this RR

Median (50%) 

You, past RRs You, ≥x, past RRs Others, this RR 1st Quartile (25%) 

Serum History Comments 

#324 Fresh frozen Native, single-source 

#325 Fresh frozen 25:35 blend of #324 and #326 

#326 Fresh frozen Native, single-source 

#327 Lyophilized - 28:184, 59:319 Native, single-source 

#328 Lyophilized - 31:195, 35:214, 43:244 Manipulated, multi-source 

Individualized Report Page 12 / 14 

D13
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.

NIST, this RR

 

Set 1 of 39 

Individualized RR LX Report: FSV-BA 

Total Lutein&Zeaxanthin 

[Analyte], μg/mL

Your [Analyte], μg/mL

Median [Analyte], μg/mL 

Apparent Precision, SD 

324325326184319327195214244328 

Apparent Precision, SD 

Long-term Precision, SD Concordance, SD 

3rd Quartile (75%) 

You, this RR You, ≥x, this RR

Median (50%) 

You, past RRs You, ≥x, past RRs Others, this RR 1st Quartile (25%) 

Serum History Comments 

#324 Fresh frozen Native, single-source 

#325 Fresh frozen 25:35 blend of #324 and #326 

#326 Fresh frozen Native, single-source 

#327 Lyophilized - 28:184, 59:319 Native, single-source 

#328 Lyophilized - 31:195, 35:214, 43:244 Manipulated, multi-source 

Individualized Report Page 13 / 14 

D14
Set 1 of 39 

Individualized Round Robin LX Report: FSV-BA 

Graphical Comparability Summary 

Total Retinol α-Tocopherol Total β-Carotene Tot

D15

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

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

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

Individualized Report 
 

 

 

Appendix E. Shipping Package Inserts for RR25 

The following five items were included in each package shipped to an RR25 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
May 1, 2006 

Dear Colleague: 

UNITED STATES DEPARTMENT OF COMMERCE 

National lnetitute af Standards and Technology 

Gaithersburg, Maryland 20899-

The samples within this package constitute the second Vitamin C Round Robin (RR25) of the fiscal year (FY) 

06 Micronutrients Measurement Quality Assurance Program. 

RR25 consists of four vials of frozen serum test samples (#72, #89, #111, and #116), one vial of ascorbic acid 

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

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

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

volumes used. (Routine 0.5 g gravimetric measurements are generally 10-fold more accurate than routine 0.5 

mL volumetric measurements.) 

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

QAP for Vitamin C. Please use these 

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

target value and :::::95% confidence interval for Control #1is8.41 ±0.61 μmol/L sample; the target value and 

:::::95% confidence interval for Control #2 is 28.05 ±0.49 μmol/L sample. 

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

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

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

observe unusually large variation in replicate analyses. 

The report for RR24 was mailed during the last week of April. If you find your results for RR24 

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). 

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 the RR25 samples by September 4, 2006. We would appreciate 

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

kept confidential. 

ice Brown Thomas 

search Chemist 

Analytical Chemistry Division 

Chemical Science and Technology Laboratory 

Enclosures: Protocols, Preparation and Analysis of Control Materials and Analysis of Test ~amples 

RR25 Report Form for Ascorbic Acid Solid Control Material Preparation 

RR25 Report Form for Control Material and Test Sample Analyses 

N•Si 

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

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

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

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

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

measurement system may not be suitable for MPA-preserved samples. Please contact us: 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 25 

NIST Micronutrient Measurement Quality Assurance Program 

Preparation and Validation of Ascorbic Acid Solid Control Material 

STOCK SOLUTION 

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

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

DILUTE SOLUTION 1 

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

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

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

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

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

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

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

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

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

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

DILUTE SOLUTION 2 

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

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

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

DILUTE SOLUTION 3 

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

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

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

Please return by Sept 4, 2006 

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 25 

NIST Micronutrient Measurement Quality Assurance Program 

Analysis of Control Materials and Test Samples 

Sample Replicate 1 Replicate 2 Units 

Dilute Solution 1 μmol/L of Dilute Solution 

Dilute Solution 2 μmol/L of Dilute Solution 

Dilute Solution 3 μmol/L of Dilute Solution 

5% MPA Diluent μmol/L of Diluent 

μmol/L of Sample Serum Control #1 Target: 8.5 ±0.5 μmol/L 

μmol/L of Sample Serum Control #2 Target: 28.1 ±1.0 μmol/L 

Serum Test Sample #72 μmol/L of Sample 

Serum Test Sample #89 μmol/L of Sample 

Serum Test Sample #111 μmol/L of Sample 

Serum Test Sample #116 μmol/L of Sample 

Were samples frozen upon receipt? Yes | No 

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

If “Other”, please describe:
	

COMMENTS: 

Please return by Sept 4, 2006 

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 25 

NIST Micronutrients Measurement Quality Assurance Program 

Packing List and Shipment Receipt Confirmation Form 

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

Sample Form 

VitC #72 Liquid frozen (1:1 serum:10% MPA) 

VitC #89 Liquid frozen (1:1 serum:10% MPA) 

VitC #111 Liquid frozen (1:1 serum:10% MPA) 

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

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

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

Control Solid AA 

Please 1) Open the pack immediately 

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

3) Check if the samples arrived frozen 

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

5) Complete the following information 

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

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

1) Date this shipment arrived: ___________________________ 

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

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

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

4) Did the samples arrive frozen? Yes | No 

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

6) When do you anticipate analyzing these samples? ________________________ 

Your prompt return of this information is appreciated. 

The M2QAP Gang 

Mail: M2QAP 

NIST, Stop 8392 Fax: 301-977-0685 

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

E7
 

 

 

 

Appendix F. Final Report for RR25 

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
October 12, 2006 

Dear Colleague: 

UNITED STATES DEPARTMENT OF COMMERCE 

Natianal lnatitute af Standards and Technology 

Gaithersburg, Maryland 20899-

Enclosed is the summary report of the results for Round Robin 25 (RR 25) 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 25 consisted of four test samples (Sera 72, 89, 111, and 116), two serum control materials, 

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

samples can be found in the enclosed report. 

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

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

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

301-948-3730. If your measured values do not agree with the certified values, we suggest that 

you contact us for consultation. 

Samples for the first vitamin C round robin (RR 26) of the 2007 M2

QAP will be shipped during 

the week of November 13, 2006. 

Please save the date! We will host the next Micronutrients Measurement Quality Assurance Workshop 

in conjunction with the Experimental Biology meeting on May 2, 2007 at the Convention Center in 

Washington, DC. We will provide you with more details as our plans our finalized. 

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

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

jbthomas@nist.gov; or f: : 301-9 7. 0685. 

b~ Jean e rown Thomas 

Research Chemist 

Analytical Chemistry Division 

Chemical Science and Technology Laboratory 

Enclosures 

Cc: L. C. Sander 

D.L. Duewer 

F2

N•Si 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

The NIST M2QAP Vitamin C Round Robin 25 (RR25) report consists of 

Page “Individualized” Report 

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

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

samples. 

2 Graphical summary of your RR25 sample measurements. 

Page “All Lab” Report 

1 A tabulation of results and summary statistics for Total Ascorbic Acid [TAA] in the RR25 

samples and control/calibration solutions. 

Serum-based Samples. Two serum controls and four unknowns were distributed in RR25. 

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

Control 2 (CS #2) SRM 970 level 2, ampouled in mid-1998. 

Serum 72, SRM 970 level 1, ampouled in mid-1998. An augmented serum. 

Serum 89, SRM 970 level 2, ampouled in mid-1998. An augmented serum. 

Serum 111, ampouled in 1989. It was used in some early experiments but has not previously been 

used in the M2

QAP program. 

Serum 116, ampouled in 1995, previously distributed as sample 682a in RR8 (1996) and RR10 

(1997). 

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”(≈254 nm), the observed absorbance at that maximum (≈0.55 OD), the calculated E1% #1”(≈550 

dL/g·cm). 

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

close to 0.0, slopes close to 1.0, R2

 close to 1, and root mean square error close to 0.0), the 

measurement systems for all participants are linear and reasonably well calibrated. However, several 

participants continue to have measurement systems that perform somewhat differently for the control 

solutions and the test samples. 

3)		 While it appears that Serum 111 has not been previously distributed as a M2

QAP sample, the median 

value from RR25 agrees very well with the value assigned to the material by Dr. Margolis in 1989. 

There has been no significant change in the median value or the variability for Serum 116, ampouled 

in 1995. 

4)		 Sera 72 and 89 are the same materials as CS #1 and CS #2, Levels 1 and 2 of SRM 970. The 

following Figure displays the reported {known Control Material, unknown Sample} pairs for the two 

levels. There is no significant difference in the results. 

F3
 

Reported Results for SRM 970 Levels 1 and 2 

Distributed as Known Control Materials and as Unknown Samples. 

All results are in mmol/L
	

0 

10 

20 

30

Distributed as Unknowns 

0 10 20 30 

Distributed as Control Materials 

F4
 

 

 

Appendix G. “All-Lab Report” for RR25 

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" 25 - September 2006 

Control / Calibration Samples MPA Dilute Solution 1 Samples 

G2

Density 

Lab Date Dil:1 Dil:2 Dil:3 Dil:1 Dil:2 Dil:3 MPA Inter Slope R2 RMS g/mL λmax Amax E1% CS#1 CS#2 S25:1 S25:2 S25:3 S25:4 CS#1 

VC-MA 28/08/06 56.5 28.1 14.0 53.9 28.1 14.7 0.0 0.80 0.95 0.999 0.9 1.035 242. 0.5550 557.4 8.4 27.6 8.6 27.5 12.4 42.1 8.

VC-MB 24/05/06 56.9 28.4 14.4 60.1 29.4 15.0 0.0 -0.21 1.06 1.000 0.3 1.031 243. 0.5580 556.5 8.5 29.9 8.8 29.4 10.8 45.7 8.3 

VC-MC 12/05/06 56.6 28.4 14.0 55.4 28.2 14.3 0.0 0.36 0.98 1.000 0.4 1.031 243. 0.5677 569.2 8.8 28.0 8.5 28.2 11.0 38.7 8.

VC-ME 05/09/06 57.6 29.3 14.2 55.8 31.1 14.3 0.0 0.77 0.97 0.997 1.6 1.028 244. 0.5251 517.6 6.5 27.3 7.5 26.5 11.6 42.0 5.

VC-MG 25/08/06 59.0 29.6 15.2 60.1 28.4 13.6 0.0 -1.10 1.03 0.998 1.3 1.030 243.2 0.5990 576.1 8.7 30.1 9.4 31.1 12.9 49.9 9.5 

VC-MH 01/09/06 62.3 31.1 15.3 62.2 30.9 15.2 0.0 -0.04 1.00 1.000 0.1 1.033 243.7 0.6210 565.6 8.3 25.4 8.2 25.8 12.0 40.7 8.4 

VC-MI 05/09/06 56.3 27.8 13.6 57.8 26.0 12.6 0.0 -1.07 1.03 0.998 1.5 1.030 8.5 28.5 8.7 27.3 10.8 41.8 9.

VC-MJ 10/08/06 60.0 31.1 13.8 56.4 29.7 14.5 0.4 0.96 0.93 1.000 0.6 1.022a 255a 0.355a 336.1a 10.5 29.5 10.2 29.0 14.6 b 10.3 

VC-MK 19/07/06 57.4 28.4 14.1 56.7 28.1 14.3 0.9 0.72 0.97 1.000 0.2 1.031 244. 0.5690 563.2 10.7 30.7 9.8 29.8 18.4 44.5 10.2 

VC-ML 02/08/06 56.3 28.4 14.2 55.7 25.6 12.6 0.0 -1.10 0.99 0.997 1.5 1.031 242. 0.5543 559.0 6.7 29.7 8.0 29.3 9.8 49.3 7.

VC-MP 18/08/06 8.7 27.6 9.2 27.6 13.4 42.4 

10 10 10 10 10 10 10 9 8 8 8 11 11 11 11 11 10 1

57.9 29.1 14.3 57.4 28.6 14.1 0.1 1.031 243.1 0.5686 558.1 8.6 28.6 8.8 28.3 12.5 43.7 8.

2.0 1.2 0.5 2.6 1.8 0.9 0.3 0.002 0.8 0.0294 17.6 1.3 1.6 0.8 1.6 2.4 3.6 1.

56.3 27.76 13.6 53.9 25.61 12.6 0.0 1.028 242.0 0.5251 517.6 6.5 25.4 7.5 25.8 9.8 38.7 5.

56.6 28.37 14.0 55.7 28.12 13.8 0.0 1.030 242.8 0.5548 557.2 8.4 27.6 8.3 27.4 10.9 41.8 8.

57.1 28.39 14.1 56.5 28.27 14.3 0.0 1.031 243.1 0.5629 561.1 8.5 28.5 8.7 28.2 12.0 42.3 8.5 

58.7 29.51 14.4 59.5 29.66 14.6 0.0 1.031 243.8 0.5765 566.5 8.8 29.8 9.3 29.4 13.2 45.4 9.

62.3 31.14 15.3 62.2 31.09 15.2 0.9 1.035 244.0 0.6210 576.1 10.7 30.7 10.2 31.1 18.4 49.9 10.

1.1 0.7 0.3 1.8 1.9 0.7 0.0 0.001 1.1 0.0122 6.7 0.3 1.7 0.9 1.6 1.7 2.8 1.

2 2 2 3 7 5 0.12 0.46 2.2 1.2 4 6 10 6 14 7 13 

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

N N 

Average Average 

SD SD 

Min Min 

%25 %25 

Median Median 

%75 %75 

Max Max 

MADe eSD 

CV CV 

a) 5% Trichloroacetic acid solution 

b) Miss-labeled sample 

All Lab Report 
Appendix H. Representative “Individualized Report” for RR25 

Each participant in RR25 received an “Individualized Report” reflecting their reported 

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

“VC-MA”. 

H1
 

Set 1 of 11 

Vitamin C "Round Robin" 25 Report: Participant VC-MA 

Date RR Method 

02/23/04 20 HPLC-EC 

09/13/04 21 HPLC-EC 

03/08/05 22 HPLC-EC 

10/17/05 23 HPLC-EC 

03/09/06 24 HPLC-EC 

08/28/06 25 HPLC-EC 

Mean 

SD 

CV 

Date RR Sample 

02/23/04 20 CS#1 

09/13/04 21 CS#1 

03/08/05 22 CS#1 

10/17/05 23 CS#1 

03/09/06 24 CS#1 

08/28/06 25 CS#1 

02/23/04 20 CS#2 

09/13/04 21 CS#2 

03/08/05 22 CS#2 

10/17/05 23 CS#2 

03/09/06 24 CS#2 

08/28/06 25 CS#2 

11/18/02 16 S16:1 

11/13/03 19 S19:4 

02/23/04 20 S20:3 

10/17/05 23 S23:4 

08/28/06 25 S25:1 

03/20/03 18 S18:3 

02/23/04 20 S20:4 

03/08/05 22 S22:4 

08/28/06 25 S25:2 

MPA Dilute Solution 1 

Density Spectrophotometry 

g/mL 

1.031 

1.030 

1.034 

1.030 

1.031 

1.039 

1.032 243.3 0.56 566.3 

0.004 0.8 0.01 10.6 

0.35 0.34 1.0 1.9 

[TAA] mmol/Lsample 

Rep1 Rep2 Fadj Mean SDdup

7.8 8.0 1.0 7.9 0.1 

8.1 7.9 1.0 8.0 0.1 

8.5 8.7 1.0 8.6 0.1 

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 

25.8 26.2 1.0 26.0 0.3 

26.2 27.2 1.0 26.7 0.7 

29.0 29.0 1.0 29.0 0.0 

29.4 30.5 1.0 30.0 0.8 

29.2 29.1 1.0 29.2 0.1 

27.2 28.1 1.0 27.6 0.6 

8.8 8.8 1.0 8.8 0.0 

7.8 8.6 1.0 8.2 0.5 

8.3 8.1 1.0 8.2 0.1 

8.6 8.8 1.0 8.7 0.1 

8.7 8.5 1.0 8.6 0.2 

28.8 29.2 1.0 29.0 0.3 

25.9 25.2 1.0 25.5 0.5 

29.4 29.4 1.0 29.4 0.0 

27.6 27.4 1.0 27.5 0.1 

Control/Calibration Solutions 

Ymeas = Inter + Slope* Xgrav 

λmax Amax E1% Inter Slope R2 SEE 

243.0 0.552 560.7 -0.4 1.05 1.000 0.65 

244.0 0.555 562.2 -0.1 0.99 1.000 0.10 

243.0 0.559 562.9 0.2 1.06 1.000 0.24 

244.0 0.562 567.9 -0.6 1.09 0.998 1.47 

244.0 0.568 586.7 0.2 1.13 1.000 0.41 

242.0 0.555 557.4 0.8 0.95 0.999 0.92 

0.63 

0.50 

N Mean SDrepeat SDreprod 

6 8.6 0.1 0.6 

6 28.1 0.5 1.6 

5 8.5 0.3 0.3 

4 27.9 0.3 1.8 

08/28/06 25 S25:3 12.3 12.4 1.0 12.4 0.1 

ND 08 2 61.6 0.4 27.6 

08/20/97 10 S10:2 163.0 161.3 0.5 81.1 0.6 

08/28/06 25 S25:4 42.0 42.2 1.0 42.1 0.2 

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

Micronutrients Measurement Quality Assurance Program 

National Institute of Standards and Technology 

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

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

Individualized Report Page 1/2 

H2
 

 

 NIST, RR 22

Set 1 of 11 

Vitamin C "Round Robin" 25 Report: Participant VC-MA 

Total Ascorbic Acid 

[Total Ascorbic Acid], μmol/L 

Your [Total Ascorbic Acid], μmol/L

S16:1S19:4S20:3S23:4S25:1

Apparent Precision, SD 

S18:3S20:4S22:4S25:2S25:3S08:3S10:2S25:4 

Median [Total Ascorbic Acid], μmol/L 

Concordance, SD 

3rd Quartile (75%) You, RR 25 Median (50%) You, RR 20-24 Others, RR 25 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 

S25:1 VitC #72, previously distributed in RRs 16, 19, 20, and 23 

S25:2 VitC #89, previously distributed in RRs 18, 20, and 22 

S25:3 VitC #111 

S25:4 VitC #116, previously distributed in RRs 8 and 10 

Individualized Report Page 2 / 2 

H3