NISTIR 7880-6

NIST Micronutrients Measurement 

Quality Assurance Program 

Summer 2009 

Comparability Studies 

Results for Round Robin LXVI 

Fat-Soluble Vitamins and Carotenoids in Human Serum 

and Round Robin 31 Ascorbic Acid in Human Serum 

David L. Duewer 

Jeanice B. Thomas 

 

 

 

NISTIR 7880-6
 

NIST Micronutrients Measurement 

Quality Assurance Program 

Summer 2009 

Comparability Studies 

Results for Round Robin LXVI 

Fat-Soluble Vitamins and Carotenoids in Human Serum 

and Round Robin 31 Ascorbic Acid in Human Serum 

David L. Duewer 

Jeanice B. Thomas 

Chemical Sciences Division 

Materials Measurement Laboratory 

April, 2013 

U.S. Department of Commerce 

Rebecca Blank, Acting Secretary 

National Institute of Standards and Technology 

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

ii
 
 

Abstract 

The National Institute of Standards and Technology coordinates the Micronutrients Measurement 

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

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

Summer 2009 MMQAP measurement comparability improvement studies: 1) Round Robin LXVI 

Fat-Soluble Vitamins and Carotenoids in Human Serum and 2) Round Robin 31 Total Ascorbic Acid 

in Human Serum. The materials for both studies were shipped to participants in June 2009; 

participants were requested to provide their measurement results by September 28, 2009. 

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

Round Robin 31: Vitamin C in Human Serum............................................................................... 2
 

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

Appendix A. Shipping Package Inserts for RR66........................................................................ A1
 

Appendix B. Final Report for RR66 ..............................................................................................B1
 

Appendix C. “All-Lab Report” for RR66 ......................................................................................C1
 

Appendix D. Representative “Individualized Report” for RR66 ............................................... D1
 

Appendix E. Shipping Package Inserts for RR31 ......................................................................... E1
 

Appendix F. Final Report for RR31............................................................................................... F1
 

Appendix G. “All-Lab Report” for RR31..................................................................................... G1
 

Appendix H. Representative “Individualized Report” for RR31............................................... 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 LXVI: Fat-Soluble Vitamins and Carotenoids in Human Serum 

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

LXVI comparability study (hereafter referred to as RR66) received five liquid-frozen human serum 

test samples for analysis. Unless multiple vials were previously requested, participants received one 

vial of each serum. These sera were shipped on dry ice to participants in June 2009. 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 RR66 consists of three documents: 

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

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

letter is reproduced as Appendix B. 

•	 The “All-Lab Report” that lists all of the reported measurement results, a number of 

consensus statistics for analytes reported by more than one participant, and the mean median 

and pooled SD from any prior distributions of the serum. This report also provides a 

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

commonly reported analytes. This report is reproduced as Appendix C. 

1
 
 

 

 

 

 

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

analytes reported by at least five participants. This report also provides a graphical summary 

of their measurement comparability. The graphical tools used in this report are described in 

detail elsewhere [3]. An example “Individualized Report” is reproduced as Appendix D. 

Round Robin 31: Vitamin C in Human Serum 

Participants in the MMQAP Vitamin C in Human Serum Round Robin 31 comparability study 

(hereafter referred to as RR31) received four frozen serum test samples, one frozen control serum, 

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

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

dry ice to participants in June 2009. 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 RR31 consists of three documents: 

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

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

reproduced as Appendix F. 

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

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

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

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

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

is reproduced as Appendix H. 

2
 
 

References 

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

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

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

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

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

Stability, Intralaboratory Repeatability, and Interlaboratory Reproducibility. Clin Chem 

1996;42(8):1257-1262. 

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

Measurement Quality Assurance Program: Helping Participants Use Interlaboratory Comparison 

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

1999;71(9):1870-1878. 

3
 
Appendix A. Shipping Package Inserts for RR66 

The following three items were included in each package shipped to an RR66 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
•• I 

UNmD STATES DEPARTMENT OF COMMERl;E. National Institute of Standards and Technology 

Gaithersburg, Maryland 20899- '· 

June 1, 2009 

Dear Colleague: 

Enclosed are samples for the second fat-soluble ·vitamins and carotenoids in serum study (Round Robin 

LXVI) for the 2009 NIST Micronutrients Measurement Quality Assurance Program. The set of samples 

(Sera 357 - 361) consists of one vial of each of five liquid-frozen serum samples for analysis along with a 

form for reporting your results. These samples should be stored in the dark at or below -20 °C upon 

receipt. When reporting your results, please submit one value for each analyte for a given serum sample. 

If a value obtained is below your limit of quantification, please indicate this result on the form by using 

NQ (Not Quantified). Results are due to NIST by September 28, 2009. Results received more than two 

weeks after the due date may not be included in the summary report for this round robin study. The 

feedback report concerning the study will be distributed in October 2009. 

Samples should be allowed to stand a.t room temperature under subdued light until thawed. 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 will cause foaming 

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

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

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

Water should not be added to the liquid-frozen samples. 

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

325 nm (ethanol); retinyl palmitate, 975 at 325 nm (ethanol); a.-tocopherol, 75.8 at 292 nm (ethanol); ytocopherol, 91.4 at 298 nm (ethanol); a-carotene, 2800 at 444 nm (hexane); J3-carotene, 2560 at 450 nm 

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

' 

Please report your results for Round Robin LXVI by e-mail to david.duewer@nist.gov or fax to 301-977-

0685. If you have questions or comments regarding this study, please call me at (301) 975-3120 or e-mail 

me atjbthomas@nist.gov. 

ical Chemistry Division 

ical Science and Technology L.aboratory 

Enclosures 

NISI 

A2
 

 

 

Participant #: ________ Date: _____________ 

Round Robin LXVI: Human Sera 

NIST Micronutrients Measurement Quality Assurance Program 

Analyte 357 358 359 360 361 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 (357 to 361) frozen when received? Yes | No 

Comments: 

Mail: M2QAP Please return results by 

NIST, Stop 8392 28-Sep-2009 Fax: 301-977-0685 

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

A3
 

 

 

 

Participant #: ________ Date: _____________ 

Fat-Soluble Vitamins Round Robin LXVI
 

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? Vial/Cap 

#357 Liquid frozen No 2 mL amber, red cap 

#358 Liquid frozen No 2 mL amber, blue cap 

#359 Liquid frozen No 2 mL amber, green cap 

#360 Liquid frozen No 2 mL amber, green cap 

#361 Liquid frozen No 10 mL amber, silver cap 

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 arrive frozen? Yes | No 

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

6) When do you anticipate analyzing these samples? ________________________ 

Your prompt return of this information is appreciated. 

The M2QAP Gang 

Mail: M2QAP 

NIST, Stop 8392 Fax: 301-977-0685 

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

A4
 

 

 

Appendix B. Final Report for RR66 

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 30, 2009 

Dear Colleague: 

UNnaJ STATES DEPARTMENT OF COMMERCE 

Nnianal lnsdtute of Standards and Technology 

Gaithersburg, Maryland 20899-

Enclosed is the summary report of the results for round robin LXVI (RR66) of the 2009 NIST 

Micronutrients Measurement Quality Assurance Program (M2

QAP) for the fat-soluble vitamins and 

carotenoids in human serum. Included in this report are: I) 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. 

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 I to 3 standard deviations of the assigned value, 

respectively; those rated 4 are >3 standard deviations from the ~signed 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 in the process of finalizing the value-assignment for SRM 968e, Fat-Soluble Vitamins, 

Carotenoids, and Cholesterol in Human Serum. This SRM will consist of three different levels for the 

core analytes (retinal, ci-tocopherol, and P-carotene). We will notify you when the SRM becomes 

available for purchase (estimated Spring 2010). 

Samples for the first 2010 QA interlaboratory exercise will be shipped during the week of December 7, 

2009. 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. 

Sincerely, 

/ 

Jeanice B. Thomas, M.B.A 

Research Chemist 

Analytical Chemistry Division 

Chemical Science and Technology Laboratory 

Cc: L.C. Sander 

David L. Duewer, Ph.D 

Research Chemometrician 

Analytical Chemistry Division 

Chemical Science and Technology Laboratory 

NISI 

B2
 

 

 

 

 

 

 

 

 

 

 

The NIST M2QAP Round Robin LXVI (RR66) report consists of: 

Page 

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 

2 to 

n 

n+1 

Samples. 

Serum 

357 

358 

359 

360 

361 

Results 

“All Lab” Report 

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

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

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

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

Five samples were distributed in RR66. 

Description 

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

This is Level I of candidate SRM 968e. 

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

This is Level II of candidate SRM 968e. 

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

This is Level III of candidate SRM 968e. 

Fresh-frozen, native, multi-donor, prepared in 2008 

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

Fall, 2007 (SRM 968d) 

Prior Distributions 

#356:RR65-3/09 

#341 & #344:RR63-3/08, 

#351:RR64-9/08 

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

measurand in either of the two previously distributed materials. However, measurement variability 

for some analytes appears to have increased in the SRM 968d material. We will closely monitor the 

stability of this material; we hope to replace it with in the very near future. 

2)	 Candidate SRM 968e. Sera #357 to #359 are the components of candidate SRM 968e. All three of 

these materials were prepared by blending commercially available materials without spiking. The 

materials were designed to represent relatively low, middling, and relatively high levels of retinol, αTocopherol and β-carotene. We anticipate this material being available for purchase early-2010. 

3)	 Environmental Stability. The initial set of samples for Lab 110 arrived thawed. After a replacement 

set was successfully delivered, both sets (listed as 110 and 110.1) were analyzed under reproducibility 

conditions. The is appreciable difference in the reported values for any analyte in any of the 

materials. 

B3
 

 

 

Appendix C. “All-Lab Report” for RR66 

The following six pages are the “All-Lab Report” as provided to all participants, with two 

exceptions: 

• the participant identifiers (Lab) have been altered. 

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

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

identification codes assigned to laboratories. The only attributed results are those 

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

summary results of the study. 

C1
 Round Robin LXVI Laboratory Results 

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

Lab 357 358 359 360 361 

C2

110.2??? 0.328 0.433 0.522 0.608 0.275 

110.3??? 0.293 0.463 0.522 0.623 0.281 

≥0.274 ≥0.380 ≥0.480 ≥0.571 ≥0.289 119.1??? 

FSV-BA 0.366 0.523 0.675 0.770 0.357 

FSV-BB 0.357 0.522 0.655 0.733 0.361 

FSV-BC 0.373 0.530 0.670 0.772 0.356 

FSV-BD 0.387 0.531 0.732 0.851 0.375 

FSV-BE 0.343 0.504 0.675 0.713 0.287 

FSV-BF 0.390 0.560 0.710 0.840 0.370 

FSV-BG 0.350 0.497 0.645 0.748 0.336 

FSV-BH 0.347 0.511 0.619 0.720 0.315 

FSV-BJ 0.331 0.473 0.626 0.718 0.321 

FSV-BK 0.364 0.494 0.659 0.722 0.450 

FSV-BL 0.320 0.430 0.540 0.600 0.290 

FSV-BM 0.370 0.480 0.690 0.730 0.370 

FSV-BN 0.316 0.428 0.550 0.638 0.291 

FSV-BNa 0.309 0.453 0.552 0.630 0.284 

FSV-BO 0.381 0.549 0.668 0.925 0.371 

FSV-BP 0.351 0.497 0.654 0.752 0.314 

FSV-BQ 0.440 0.660 0.840 0.960 0.430 

FSV-BR 0.360 0.530 0.720 0.720 0.340 

≥0.655 ≥0.554 ≥0.455 ≥0.421 ≥1.075 FSV-BS 

≥0.330 ≥0.428 ≥0.549 ≥0.704 ≥0.375 FSV-BT 

FSV-BU 0.377 0.547 0.677 0.706 0.291 

FSV-BV 0.400 0.559 0.627 0.719 0.330 

FSV-BW 0.350 0.495 0.655 0.732 0.327 

FSV-CC 0.393 0.520 0.688 0.758 0.303 

FSV-CD 0.320 0.450 0.580 0.670 0.300 

FSV-CE 0.353 0.451 0.554 0.601 0.310 

FSV-CF 0.361 0.506 0.664 0.645 0.332 

FSV-CG 0.308 0.459 0.497 0.688 0.337 

FSV-CI 0.344 0.507 0.643 0.715 0.340 

FSV-CW 0.493 0.624 0.784 0.993 0.700 

FSV-CZ 0.311 0.436 0.554 0.605 0.296 

FSV-DD 0.330 0.480 0.650 0.690 0.310 

≥0.330 ≥0.471 ≥0.603 ≥0.675 ≥0.256 FSV-DV 

FSV-EE 0.339 0.479 0.601 0.678 0.312 

357 358 359 360 361 

0.274 0.380 0.480 0.571 0.289 

0.655 0.554 0.455 0.421 1.075 

0.330 0.428 0.549 0.704 0.375 

0.352 0.487 0.638 0.693 0.243 

0.330 0.471 0.603 0.675 0.256 

357 358 359 360 361 

0.002 0.020 0.089 0.042 0.002 

0.006 0.021 0.093 0.043 0.000 

0.019 0.063 0.155 0.044 0.029 

0.007 0.021 0.070 0.036 0.007 

0.016 0.049 0.219 0.045 0.024 

nq nq 0.092 nq nq 

0.003 0.014 0.074 0.032 0.003 

0.005 0.017 0.081 0.033 nd 

0.008 0.026 0.101 0.053 0.005 

0.011 <0.01 0.057 0.051 <0.01 

0.008 nd 0.091 0.043 0.013 

0.008 0.019 0.061 0.046 0.029 

357 358 359 360 361 

7.09 10.03 17.00 9.68 4.91 

6.28 10.66 17.54 10.00 5.07 

6.80 10.51 18.74 11.11 6.14 

6.62 9.99 18.18 10.16 5.88 

6.49 9.94 17.88 10.14 5.81 

7.10 10.70 20.50 11.90 6.50 

5.66 9.22 18.15 9.34 2.41 

7.10 10.50 18.80 10.90 5.00 

6.43 9.95 18.40 10.41 5.86 

6.98 10.64 18.71 10.45 5.67 

6.08 9.99 18.34 10.24 5.50 

6.86 10.46 19.26 10.83 6.37 

7.32 11.20 19.38 11.20 6.46 

7.10 10.20 19.70 10.90 6.20 

6.10 8.80 15.53 9.27 4.51 

5.96 9.23 15.44 9.01 4.48 

6.60 10.20 18.10 10.70 5.70 

6.52 9.71 17.53 8.70 5.24 

8.40 12.20 22.20 13.50 7.70 

6.70 11.00 19.40 10.75 4.05 

6.48 10.02 17.76 10.10 5.38 

6.40 9.54 18.56 8.99 4.46 

7.730 10.990 16.820 10.760 5.870 

6.14 9.59 18.00 10.06 4.91 

7.73 11.54 20.42 11.73 nq 

7.54 11.48 20.58 11.57 6.74 

8.52 12.96 23.96 12.94 7.12 

7.60 11.20 19.50 10.40 6.80 

5.47 8.76 13.35 8.88 4.47 

6.84 10.87 19.42 10.74 5.52 

8.15 12.01 21.03 12.09 6.11 

6.50 9.89 18.03 10.42 4.98 

6.10 9.20 15.60 8.90 3.00 

6.90 10.40 19.60 12.90 7.00 

35

1.1

1.1

1.8

2.0

1.8

1.7

1.8

2.2

1.7

1.3

1.3

1.6

1.7

1.6

1.8

1.6

1.6

1.5

1.7

2.0

1.7

N 33 33 33 33 33 5 5 5 5 5 11 9 12 11 9 34 34 34 34 33 2

Min 0.293 0.428 0.497 0.600 0.275 0.274 0.380 0.455 0.421 0.243 0.002 0.014 0.057 0.032 0.000 5.47 8.76 13.35 8.70 2.41 1.1

Median 0.351 0.497 0.654 0.719 0.327 0.330 0.471 0.549 0.675 0.289 0.008 0.021 0.090 0.043 0.007 6.75 10.30 18.48 10.44 5.67 1.7

Max 0.493 0.660 0.840 0.993 0.700 0.655 0.554 0.638 0.704 1.075 0.019 0.063 0.219 0.053 0.029 8.52 12.96 23.96 13.50 7.70 2.2

SD 0.033 0.049 0.052 0.061 0.044 0.032 0.064 0.102 0.043 0.069 0.005 0.005 0.020 0.004 0.009 0.52 0.86 1.39 0.85 1.04 0.18

CV 9 10 8 8 14 10 14 19 6 24 58 26 23 10 125 8 8 8 8 18 1

Npast 0 0 0 28 30 0 0 0 5 9 0 0 0 9 7 0 0 0 31 32 

Medianpast 0.760 0.344 0.708 0.332 0.045 0.010 10.552 5.759 

SDpast 0.066 0.025 0.130 0.043 0.012 0.006 0.812 0.764 

NIST 0.346 0.490 0.672 0.702 0.313 7.01 10.25 19.56 10.98 5.94 2.0

NAV 0.349 0.495 0.662 0.710 0.321 0.330 0.471 0.549 0.675 0.289 0.008 0.021 0.090 0.043 0.007 6.904 10.326 19.057 10.716 5.811 1.86

NAU 0.034 0.045 0.056 0.067 0.046 0.032 0.064 0.102 0.053 0.069 0.010 0.011 0.024 0.015 0.010 0.608 0.815 1.612 0.895 1.115 0.27

All Lab Report 
 Round Robin LXVI Laboratory Results 

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

C3

Lab 357 358 359 360 361 357 358 359 360 361 357 358 359 360 361 357 358 359 360 361 357 

110.2??? 0.094 0.265 0.369 0.299 0.071 0.00

110.3??? 0.092 0.277 0.373 0.301 0.065 0.00

119.1??? nd 0.001 0.003 0.002 0.001 0.090 0.255 0.389 0.303 0.083 0.090 0.254 0.386 0.301 0.082 0.00

FSV-BA 0.097 0.067 0.202 0.267 0.073 0.090 0.244 0.415 0.295 0.092 0.085 0.231 0.399 0.280 0.085 0.005 0.013 0.016 0.015 0.007 0.00

FSV-BB 0.084 0.076 0.205 0.255 0.085 0.086 0.225 0.346 0.265 0.079 0.082 0.213 0.330 0.249 0.074 0.004 0.012 0.016 0.016 0.004 0.00

FSV-BC 

FSV-BD 

FSV-BE 0.078 0.234 0.441 0.273 0.065
 

FSV-BF
 0.069 0.208 0.350 0.252 0.053
 

FSV-BG
 0.094 0.264 0.462 0.311 0.082 0.00

FSV-BH nq 

FSV-BJ 

0.079 0.236 0.387 0.241 0.059 0.079 0.224 0.371 0.241 0.059 nq 0.012 0.016 nq nq 

0.088 0.269 0.502 0.310 0.092 nq 

FSV-BK 

FSV-BL 

FSV-BM 

FSV-BN 0.005 0.010 0.020 0.015 0.008 0.088 0.213 0.364 0.258 0.074 0.083 0.203 0.344 0.244 0.065 0.01

FSV-BNa 0.007 0.016 0.018 0.015 0.007 0.092 0.235 0.366 0.257 0.070 0.085 0.219 0.348 0.242 0.063 0.01

FSV-BO 0.089 0.219 0.307 0.271 0.084 0.00

FSV-BP 0.063 0.261 0.407 0.287 0.056 nd 

FSV-BQ 

FSV-BR 

FSV-BS ≥0.029 ≥0.145 ≥0.330 ≥0.234 ≥0.012 0.029 0.145 0.330 0.234 0.012 0.00

FSV-BT 0.066 0.046 0.102 0.106 0.033 0.091 0.214 0.299 0.257 0.079 0.089 0.206 0.291 0.252 0.077 0.004 0.013 0.015 0.012 0.004 0.00

FSV-BU 0.102 0.289 0.472 0.310 0.100 0.00

FSV-BV 0.111 0.292 0.444 0.352 0.090 0.01

FSV-BW 0.099 0.266 0.493 0.314 0.064 0.00

FSV-CC 

FSV-CD 0.182 0.245 0.321 0.250 0.167 0.02

FSV-CE 0.168 0.344 0.585 0.486 0.153 

FSV-CF 

FSV-CG nq nq 0.179 0.238 0.127 0.071 0.205 0.283 0.226 0.066 0.067 0.192 0.269 0.212 0.061 nq 0.013 0.014 0.014 nq 0.00

FSV-CI 0.075 0.206 0.402 0.229 0.055 0.01

FSV-CW 0.172 0.100 0.262 0.312 0.096 0.100 0.239 0.386 0.303 0.051 0.00

FSV-CZ 0.089 0.199 0.277 0.229 0.077
 

FSV-DD
 

FSV-DV
 

FSV-EE
 

N 4 4 5 5 5 24 24 24 24 24 9 9 9 9 9 5 8 8 7 6 1

Min 0.066 0.046 0.102 0.106 0.033 0.063 0.199 0.277 0.226 0.051 0.029 0.145 0.269 0.212 0.012 0.004 0.001 0.003 0.002 0.001 0.00

Median 0.091 0.072 0.202 0.255 0.085 0.090 0.241 0.386 0.280 0.075 0.083 0.213 0.344 0.244 0.065 0.005 0.013 0.016 0.015 0.006 0.00

Max 0.172 0.100 0.262 0.312 0.127 0.182 0.344 0.585 0.486 0.167 0.090 0.254 0.399 0.301 0.085 0.007 0.016 0.020 0.016 0.008 0.02

SD 0.023 0.022 0.034 0.025 0.018 0.010 0.036 0.070 0.038 0.016 0.006 0.016 0.039 0.012 0.013 0.001 0.001 0.002 0.001 0.003 0.00

CV 25 31 17 10 21 11 15 18 14 21 7 8 11 5 19 26 6 12 6 46 5

Npast 0 0 0 4 5 0 0 0 20 22 0 0 0 7 9 0 0 0 5 5 

Medianpast 0.267 0.084 0.268 0.076 0.248 0.075 0.013 0.005 

SDpast 0.027 0.023 0.020 0.013 0.010 0.008 0.003 0.002 

NIST 

NAV 

NAU 

nq nq nq 0.271 nq 0.115 0.248 0.440 0.266 0.074 0.094 0.196 0.380 nq nq 0.021 0.052 0.060 nd nd nq 

0.091 0.072 0.202 0.263 0.085 

0.036 0.044 0.022 

0.103 0.243 0.413 0.269 0.075 

0.024 0.039 0.090 0.045 0.018 

0.088 0.204 0.362 0.244 0.065 

0.014 0.027 0.047 0.027 0.013 

0.013 0.032 0.038 0.015 0.006 

0.012 0.033 0.034 0.005 0.003 

0.00

0.00

All Lab Report 
 Round Robin LXVI Laboratory Results 

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

Lab 357 358 359 360 361 

C4

110.2??? 0.219 0.573 0.815 0.312 0.192 

110.3??? 0.204 0.594 0.833 0.338 0.163 

119.1??? 0.243 0.691 1.004 0.437 0.304 

FSV-BA 0.233 0.631 0.966 0.405 0.329 

FSV-BB 0.248 0.640 0.936 0.398 0.308 

FSV-BC 

FSV-BD 

FSV-BE 

FSV-BF 

FSV-BG 0.242 0.665 1.038 0.418 0.285 

FSV-BH 0.236 0.642 0.965 0.375 0.254 

FSV-BJ 0.234 0.594 1.215 0.387 0.270 

FSV-BK 

FSV-BL 

FSV-BM 

FSV-BN 0.255 0.536 0.808 0.355 0.205 

FSV-BNa 0.210 0.558 0.818 0.328 0.166 

FSV-BO 0.195 0.471 0.632 0.314 0.253 

FSV-BP 0.268 0.933 1.522 0.546 0.182 

FSV-BQ 

FSV-BR 

FSV-BS 0.169 0.490 1.055 0.366 0.127 

FSV-BT 0.241 0.575 0.775 0.379 0.305 

FSV-BU 0.250 0.598 1.073 0.380 0.308 

FSV-BV 0.308 0.803 1.113 0.515 0.342 

FSV-BW 0.241 0.682 1.140 0.432 0.208 

FSV-CC 

FSV-CD 0.148 0.219 0.303 0.178 0.148 

FSV-CE 

FSV-CF 

FSV-CG 0.192 0.541 0.696 0.326 0.245 

FSV-CI 

FSV-CW 

FSV-CZ 

FSV-DD 

FSV-DV 

FSV-EE 

357 358 359 360 361 

0.101 0.283 0.424 0.177 0.120 

0.127 0.339 0.457 0.225 0.156 

0.101 0.255 0.337 0.162 0.110 

0.141 0.383 0.533 0.248 0.151 

0.113 0.281 0.374 0.175 0.101 

0.115 0.294 0.383 0.173 0.085 

0.121 0.279 0.304 0.189 0.120 

0.104 0.296 0.337 0.180 0.116 

0.127 0.287 0.361 0.190 0.089 

357 358 359 360 361 

0.058 0.080 0.026 0.058 0.033 

0.048 0.053 0.027 0.058 0.031 

0.032 0.033 0.023 0.038 0.028 

0.043 0.051 0.031 0.058 0.041 

0.047 0.050 0.034 0.056 0.040 

0.050 0.051 0.032 0.060 0.041 

0.059 0.071 0.047 0.074 0.045 

0.036 0.045 0.034 0.056 0.034 

0.047 0.046 0.024 0.055 0.033 

0.047 0.048 0.025 0.054 0.030 

0.091 0.050 0.028 0.062 0.042 

0.044 0.064 0.043 0.068 0.036 

0.015 0.018 0.012 0.032 0.029 

0.042 0.041 0.028 0.051 0.032 

0.047 0.050 0.029 0.049 0.035 

0.049 0.048 0.023 0.061 0.037 

0.041 0.036 0.017 0.075 0.029 

0.041 0.047 0.030 0.045 0.035 

0.056 0.068 0.048 0.072 0.052 

0.052 0.049 0.031 0.060 0.048 

357 358 359 360 361 

0.015 0.017 0.013 0.017 0.016 

0.017 0.020 0.014 0.017 0.015 

0.020 0.027 0.031 0.023 0.016 

0.012 0.022 0.016 <0.01 <0.01 

357 35

0.060 0.05

0.073 0.10

0.071 0.08

0.064 0.08

0.073 0.07

0.062 0.07

0.122 0.12

0.064 0.05

0.078 0.09

0.108 0.1

N 19 19 19 19 19 9 9 9 9 9 20 20 20 20 20 4 4 4 3 3 10 

Min 0.148 0.219 0.303 0.178 0.127 0.101 0.255 0.304 0.162 0.085 0.015 0.018 0.012 0.032 0.028 0.012 0.017 0.013 0.017 0.015 0.060 0.05

Median 0.236 0.594 0.965 0.379 0.253 0.115 0.287 0.374 0.180 0.116 0.047 0.049 0.029 0.058 0.035 0.016 0.021 0.015 0.017 0.016 0.072 0.08

Max 0.308 0.933 1.522 0.546 0.342 0.141 0.383 0.533 0.248 0.156 0.091 0.080 0.048 0.075 0.052 0.020 0.027 0.031 0.023 0.016 0.122 0.12

SD 0.025 0.079 0.219 0.061 0.081 0.017 0.012 0.055 0.013 0.022 0.007 0.005 0.006 0.006 0.008 0.004 0.004 0.002 0.012 0.02

CV 11 13 23 16 32 15 4 15 7 19 16 10 21 11 22 23 18 15 16 2

Npast 0 0 0 15 17 0 0 0 7 8 0 0 0 16 18 0 0 0 5 7 0 

Medianpast 0.372 0.272 0.176 0.116 0.059 0.039 0.020 0.015 

SDpast 0.033 0.052 0.027 0.018 0.010 0.006 0.009 0.002 

NIST 0.175 0.389 0.733 nq 0.262 0.157 0.319 0.603 0.187 nd 0.042 0.038 0.017 0.056 0.026 0.067 0.10

NAV 0.205 0.492 0.842 0.377 0.258 0.136 0.303 0.488 0.184 0.116 0.044 0.043 0.023 0.057 0.030 0.016 0.021 0.015 0.017 0.016 0.070 0.09

NAU 0.070 0.187 0.251 0.082 0.079 0.036 0.057 0.176 0.032 0.022 0.012 0.014 0.011 0.014 0.011 0.015 0.02

All Lab Report 
 Round Robin LXVI Laboratory Results 

Total Zeaxanthin, μg/mL Total Lutein&Zeaxanthin, μg/mL Coenzyme Q10, μg/mL Phylloquinone (K1), ng/mL 25-hy

C5

Lab 357 358 359 360 361 357 358 359 360 361 357 358 359 360 361 357 358 359 360 361 357 3

110.2??? 0.154 0.148 0.159 0.113 0.083 

110.3??? 0.127 0.156 0.164 0.114 0.076 

119.1??? 0.032 0.034 0.031 0.023 0.035 0.119 0.112 0.124 0.104 0.085
 

FSV-BA
 0.105 0.129 0.157 0.102 0.086 00.007 

FSV-BB 0.046 0.059 0.039 0.031 0.037 0.110 0.148 0.199 0.108 0.091
 

FSV-BC
 

FSV-BD
 

FSV-BE
 0.945 1.440 0.806 0.656 0.862 0.538 2.971 1.174 0.267
 0.454 

FSV-BF
 

FSV-BG
 0.105 0.131 0.174 0.097 0.079
 

FSV-BH
 0.028 0.026 0.025 0.020 0.039 0.110 0.117 0.141 0.080 0.044 nq 0

FSV-BJ 

FSV-BK 

FSV-BL 

FSV-BM
 

FSV-BN
 0.045 0.044 0.039 0.031 0.052 0.112 0.109 0.132 0.086 0.065 

FSV-BNa 0.045 0.042 0.040 0.029 0.041 0.093 0.111 0.128 0.087 0.058
 

FSV-BO
 0.009 0.013 0.007 0.004 0.006 0.128 0.136 0.156 0.113 0.098
 

FSV-BP
 0.068 0.139 0.105 0.081 0.060
 

FSV-BQ
 

FSV-BR
 

FSV-BS
 0.133 0.162 0.216 0.164 0.147
 

FSV-BT
 0.027 0.030 0.025 0.022 0.029 0.104 0.097 0.133 0.095 0.089 1.023 1.199 1.124 0.654
 0.979 

FSV-BU
 0.116 0.134 0.128 0.095 0.074
 

FSV-BV
 0.104 0.107 0.118 0.088 0.069 

FSV-BW 0.105 0.122 0.142 0.094 0.076
 

FSV-CC
 

FSV-CD
 0.185 0.211 0.236 0.157 0.122
 

FSV-CE
 

FSV-CF
 

FSV-CG
 0.108 0.122 0.120 0.098 0.095
 

FSV-CI
 0.103 0.114 0.139 0.085 0.067 0.022 0.022 0.020 0.019 0.025 0.440 2.669 1.117 0.163 0.360 

FSV-CW 0.053 0.048 0.052 0.058 0.075 0.183 0.167 0.187 0.138 0.153 1.141 1.605 0.957 0.663
 0.953 

FSV-CZ
 0.990 1.554 0.943 0.701
 0.871 

FSV-DD
 

FSV-DV
 

FSV-EE
 0.663 1.336 0.872 0.682 0.887 

N 9 9 9 9 9 20 20 20 20 20 5 5 5 5 5 2 2 2 2 2 1 

Min 0.006 0.009 0.013 0.007 0.004 0.068 0.097 0.105 0.080 0.044 0.862 0.663 1.199 0.806 0.654 0.360 0.440 2.669 1.117 0.163 0

Median 0.037 0.032 0.034 0.031 0.023 0.110 0.130 0.142 0.098 0.081 0.887 0.990 1.440 0.943 0.663 0.407 0.489 2.820 1.146 0.215 0.007 0

Max 0.075 0.053 0.059 0.052 0.058 0.185 0.211 0.236 0.164 0.153 0.979 1.141 1.605 1.124 0.701 0.454 0.538 2.971 1.174 0.267 0

SD 0.012 0.019 0.015 0.012 0.009 0.010 0.027 0.026 0.016 0.019 0.037 0.067 0.169 0.106 0.013 

CV 32 59 45 38 38 9 21 18 16 24 4 7 12 11 2 

Npast 0 0 0 7 10 0 0 0 16 19 0 0 0 7 9 0 0 0 0 0 0 

Medianpast 0.030 0.024 0.097 0.086 0.900 0.618 

SDpast 0.015 0.009 0.024 0.018 0.184 0.147 

NIST 

NAV 

NAU 

0.027 0.030 0.025 0.028 0.023 0.095 0.132 0.157 0.084 0.070 

0.032 0.031 0.030 0.030 0.023 0.102 0.130 0.149 0.091 0.077 0.887 0.990 1.440 0.943 0.663 

0.014 0.019 0.017 0.012 0.009 0.025 0.027 0.031 0.023 0.020 0.089 0.099 0.169 0.106 0.066 

All Lab Report 
 

 

 

 

 

Round Robin LXVI Laboratory Results
 

Term Legend 

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

Min Minimum (non-NIST) quantitative value reported 

Median Median (non-NIST) quantitative value reported 

Max Maximum (non-NIST) quantitative value reported 

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

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

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

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

SDpast Pooled SD from past RR(s) 

MeanNIST Mean of NIST results 

Srep NIST's within-vial pooled standard deviation 

Shet NIST's among-vial pooled standard deviation 

SNIST Combined standard deviation for NIST analyses: √(Srep 2

 + Shet 2) 

NAV NIST Assigned Value

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

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

NAU NIST Assigned Uncertainty: √(S2

 + Sbtw 2)

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

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

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

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

nq Detected but not quantitatively determined 

≥x Concentration greater than or equal to x 

italics Not explicitly reported but calculated by NIST from reported values 

All Lab Report 

C6

Page 5 / 6 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Lab 

110.2??? 

110.3??? 

119.1??? 

FSV-BA 

FSV-BB 

FSV-BC 

FSV-BD 

FSV-BE 

FSV-BF 

FSV-BG 

FSV-BH 

FSV-BJ 

FSV-BK 

FSV-BL 

FSV-BM 

FSV-BN 

FSV-BNa 

FSV-BO 

FSV-BP 

FSV-BQ 

FSV-BR 

FSV-BS 

FSV-BT 

FSV-BU 

FSV-BV 

FSV-BW 

FSV-CC 

FSV-CD 

FSV-CE 

FSV-CF 

FSV-CG 

FSV-CI 

FSV-CW 

FSV-CZ 

FSV-DD 

FSV-DV 

FSV-EE 

NIST 

n 

% 1
 

% 2
 

% 3
 

% 4
 

Round Robin LXVI Laboratory Results 

Comparability Summary 

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

2 1 3 1 2 1 2 1
 

2 1 3 1 2 1 1 1
 

3 1 3 1 2 1 1 2 2 1 1
 

1 1 2 1 2 1 1 1 1
 

1 1 1 1 1 1 1 1 1 1 1
 

1
 

2 2
 

1 2 1 1
 

2 1 1
 

1 1 1 1 1 1 1 1
 

1 1 3 1 1 1 2 1 1 1
 

1 1 1 1 1 1 1 1
 

2 1
 

2 1
 

1 1
 

2 2 2 1 1 1 1 1 1 1 1
 

2 2 2 1 1 1 1 1 1 1 1
 

2 1 1 1 1 1 2 4 2 1
 

1 2 1 1 2 1 2
 

4 3
 

1 1
 

4 3 3 1 1 2 3
 

2 1 1 1 1 1 1 1 1 1 1
 

1 2 1 2 2 1 1 1
 

2 2 1 2 1 2 1 1
 

1 1 1 1 2 1 1 1
 

1 2
 

1 2 1 4 3 3 1 3
 

2 3 4
 

1 1
 

2 3 1 1 2 1 1 2 1
 

1 1 1 1 2 1 1 1
 

4 2 2 1 1 1 3 3 3
 

2 1 1 1
 

1
 

1 2
 

1 2
 

1 1 1 1 1 1 1 1 1 1 1
 

38 35 22 26 10 21 20 21 11 10 21
 

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

53 57 64 81 60 71 85 71 73 80 81
 

37 34 18 8 30 24 10 29 9 10 5
 

3 9 18 4 10 5 5 0 9 10 14
 

8 0 0 8 0 0 0 0 9 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
 NAU i 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 

C7

Page 6 / 6
 
 

Appendix D. Representative “Individualized Report” for RR66 

Each participant in RR66 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 RR66: 

• Total Retinol 

• trans-Retinol 

• Retinyl Palmitate 

• α-Tocopherol 

• γ/β-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 fourteen pages are the “Individualized Report” for the analytes evaluated 

by participant FSV-BA. 

D1
 

 Set 1 of 41 

Individualized Round Robin LXVI Report: FSV-BA 

Summary 

Serum 357 Serum 358 Serum 359 Serum 360 

D2

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

Total Retinol 0.366 0.349 33 0.523 0.495 33 0.675 0.662 33 0.770 0.710 33 0

Retinyl Palmitate 0.02 0.01 11 0.1 0.0 9 0.2 0.1 12 0.04 0.04 11 0

α-Tocopherol 6.62 6.90 34 9.99 10.33 34 18.18 19.06 34 10.16 10.72 34 5

γ/β-Tocopherol 2.041 1.865 21 1.581 1.419 21 2.540 2.204 21 2.687 2.307 21 1

δ-Tocopherol 0.097 0.091 4 0.067 0.072 4 0.202 0.202 5 0.267 0.263 5 0

Total β-Carotene 0.090 0.103 24 0.244 0.243 24 0.415 0.413 24 0.295 0.269 24 0

trans-β-Carotene 0.085 0.088 9 0.231 0.204 9 0.399 0.362 9 0.280 0.244 9 0

Total cis-β-Carotene 0.005 0.013 5 0.013 0.032 8 0.016 0.038 8 0.015 0.015 7 0

Total α-Carotene 0.009 0.008 18 0.033 0.032 20 0.014 0.015 19 0.054 0.044 21 0

Total Lycopene 0.233 0.205 19 0.631 0.492 19 0.966 0.842 19 0.405 0.377 19 0

trans-Lycopene 0.127 0.136 9 0.339 0.303 9 0.457 0.488 9 0.225 0.184 9 0

Total β-Cryptoxanthin 0.043 0.044 20 0.051 0.043 20 0.031 0.023 20 0.058 0.057 20 0

Total α-Cryptoxanthin 0.015 0.016 4 0.017 0.021 4 0.013 0.015 4 0.017 0.017 3 0

Total Lutein&Zeaxanthin 0.105 0.102 20 0.129 0.130 20 0.157 0.149 20 0.102 0.091 20 0

25-hydroxyvitamin D 0.007 1 0.013 2 0.020 2 0.015 2 0

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 Te

100 Bureau Drive Stop 8392 Fax

Gaithersburg, MD 20899-8392 USA Email: david.d

Individualized Report 
D3

 Set 1 of 41 

Individualized RR LXVI Report: FSV-BA

Total Retinol, μg/mL 

Apparent Precision, SD [Analyte], μg/mL

357358359356360341344351361 

Your [Analyte], μg/mL 

Apparent Precision, SD 

Concordance, SD 

Median [Analyte], μg/mL 

Long-term Precision, SD 

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

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

1st Quartile (25%) Expectation 

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

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

Serum History Comments 

#357 New Fresh-frozen, native, multi-donor 

#358 New Fresh-frozen, native, multi-donor 

#359 New Fresh-frozen, native, multi-donor 

#360 65:#356 Fresh-frozen, native, multi-donor 

#351 63:#341, 63:#344, 64:#351 Fresh-frozen, native, multi-donor 

Individualized Report Page 2 / 14 
D4

 Set 1 of 41 

Individualized RR LXVI Report: FSV-BA

Retinyl Palmitate, μg/mL 

Apparent Precision, SD [Analyte], μg/mL

357358359356360341344351361 

Your [Analyte], μg/mL 

Apparent Precision, SD 

Concordance, SD 

Median [Analyte], μg/mL 

Long-term Precision, SD 

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

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

1st Quartile (25%) Expectation 

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

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

Serum History Comments 

#357 New Fresh-frozen, native, multi-donor 

#358 New Fresh-frozen, native, multi-donor 

#359 New Fresh-frozen, native, multi-donor 

#360 65:#356 Fresh-frozen, native, multi-donor 

#351 63:#341, 63:#344, 64:#351 Fresh-frozen, native, multi-donor 

Individualized Report Page 3 / 14 
D5

 Set 1 of 41 

Individualized RR LXVI Report: FSV-BA

α-Tocopherol, μg/mL 

Apparent Precision, SD [Analyte], μg/mL

357358359356360341344351361 

Your [Analyte], μg/mL 

Apparent Precision, SD 

Concordance, SD 

Median [Analyte], μg/mL 

Long-term Precision, SD 

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

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

1st Quartile (25%) Expectation 

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

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

Serum History Comments 

#357 New Fresh-frozen, native, multi-donor 

#358 New Fresh-frozen, native, multi-donor 

#359 New Fresh-frozen, native, multi-donor 

#360 65:#356 Fresh-frozen, native, multi-donor 

#351 63:#341, 63:#344, 64:#351 Fresh-frozen, native, multi-donor 

Individualized Report Page 4 / 14 
D6

 Set 1 of 41 

Individualized RR LXVI Report: FSV-BA

γ/β-Tocopherol, μg/mL 

Apparent Precision, SD [Analyte], μg/mL

357358359356360341344351361 

Your [Analyte], μg/mL 

Apparent Precision, SD 

Concordance, SD 

Median [Analyte], μg/mL 

Long-term Precision, SD 

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

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

1st Quartile (25%) Expectation 

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

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

Serum History Comments 

#357 New Fresh-frozen, native, multi-donor 

#358 New Fresh-frozen, native, multi-donor 

#359 New Fresh-frozen, native, multi-donor 

#360 65:#356 Fresh-frozen, native, multi-donor 

#351 63:#341, 63:#344, 64:#351 Fresh-frozen, native, multi-donor 

Individualized Report Page 5 / 14 
D7

 Set 1 of 41 

Individualized RR LXVI Report: FSV-BA

Total β-Carotene, μg/mL 

Apparent Precision, SD [Analyte], μg/mL

357358359356360341344351361 

Your [Analyte], μg/mL 

Apparent Precision, SD 

Concordance, SD 

Median [Analyte], μg/mL 

Long-term Precision, SD 

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

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

1st Quartile (25%) Expectation 

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

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

Serum History Comments 

#357 New Fresh-frozen, native, multi-donor 

#358 New Fresh-frozen, native, multi-donor 

#359 New Fresh-frozen, native, multi-donor 

#360 65:#356 Fresh-frozen, native, multi-donor 

#351 63:#341, 63:#344, 64:#351 Fresh-frozen, native, multi-donor 

Individualized Report Page 6 / 14 
D8

 Set 1 of 41 

Individualized RR LXVI Report: FSV-BA

trans-β-Carotene, μg/mL 

Apparent Precision, SD [Analyte], μg/mL

357358359356360341344351361 

Your [Analyte], μg/mL 

Apparent Precision, SD 

Concordance, SD 

Median [Analyte], μg/mL 

Long-term Precision, SD 

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

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

1st Quartile (25%) Expectation 

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

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

Serum History Comments 

#357 New Fresh-frozen, native, multi-donor 

#358 New Fresh-frozen, native, multi-donor 

#359 New Fresh-frozen, native, multi-donor 

#360 65:#356 Fresh-frozen, native, multi-donor 

#351 63:#341, 63:#344, 64:#351 Fresh-frozen, native, multi-donor 

Individualized Report Page 7 / 14 
D9

 Set 1 of 41 

Individualized RR LXVI Report: FSV-BA

Total cis-β-Carotene, μg/mL 

Apparent Precision, SD [Analyte], μg/mL

357358359356360341344351361 

Your [Analyte], μg/mL 

Apparent Precision, SD 

Concordance, SD 

Median [Analyte], μg/mL 

Long-term Precision, SD 

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

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

1st Quartile (25%) Expectation 

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

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

Serum History Comments 

#357 New Fresh-frozen, native, multi-donor 

#358 New Fresh-frozen, native, multi-donor 

#359 New Fresh-frozen, native, multi-donor 

#360 65:#356 Fresh-frozen, native, multi-donor 

#351 63:#341, 63:#344, 64:#351 Fresh-frozen, native, multi-donor 

Individualized Report Page 8 / 14 
D10

 Set 1 of 41 

Individualized RR LXVI Report: FSV-BA

Total α-Carotene, μg/mL 

Apparent Precision, SD [Analyte], μg/mL

357358359356360341344351361 

Your [Analyte], μg/mL 

Apparent Precision, SD 

Concordance, SD 

Median [Analyte], μg/mL 

Long-term Precision, SD 

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

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

1st Quartile (25%) Expectation 

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

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

Serum History Comments 

#357 New Fresh-frozen, native, multi-donor 

#358 New Fresh-frozen, native, multi-donor 

#359 New Fresh-frozen, native, multi-donor 

#360 65:#356 Fresh-frozen, native, multi-donor 

#351 63:#341, 63:#344, 64:#351 Fresh-frozen, native, multi-donor 

Individualized Report Page 9 / 14 
D11

 Set 1 of 41 

Individualized RR LXVI Report: FSV-BA

Total Lycopene, μg/mL 

Apparent Precision, SD [Analyte], μg/mL

357358359356360341344351361 

Your [Analyte], μg/mL 

Apparent Precision, SD 

Concordance, SD 

Median [Analyte], μg/mL 

Long-term Precision, SD 

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

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

1st Quartile (25%) Expectation 

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

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

Serum History Comments 

#357 New Fresh-frozen, native, multi-donor 

#358 New Fresh-frozen, native, multi-donor 

#359 New Fresh-frozen, native, multi-donor 

#360 65:#356 Fresh-frozen, native, multi-donor 

#351 63:#341, 63:#344, 64:#351 Fresh-frozen, native, multi-donor 

Individualized Report Page 10 / 14 
D12

 Set 1 of 41 

Individualized RR LXVI Report: FSV-BA

trans-Lycopene, μg/mL 

Apparent Precision, SD [Analyte], μg/mL

357358359356360341344351361 

Your [Analyte], μg/mL 

Apparent Precision, SD 

Concordance, SD 

Median [Analyte], μg/mL 

Long-term Precision, SD 

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

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

1st Quartile (25%) Expectation 

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

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

Serum History Comments 

#357 New Fresh-frozen, native, multi-donor 

#358 New Fresh-frozen, native, multi-donor 

#359 New Fresh-frozen, native, multi-donor 

#360 65:#356 Fresh-frozen, native, multi-donor 

#351 63:#341, 63:#344, 64:#351 Fresh-frozen, native, multi-donor 

Individualized Report Page 11 / 14 
D13

 Set 1 of 41 

Individualized RR LXVI Report: FSV-BA

Total β-Cryptoxanthin, μg/mL 

Apparent Precision, SD [Analyte], μg/mL

357358359356360341344351361 

Your [Analyte], μg/mL 

Apparent Precision, SD 

Concordance, SD 

Median [Analyte], μg/mL 

Long-term Precision, SD 

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

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

1st Quartile (25%) Expectation 

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

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

Serum History Comments 

#357 New Fresh-frozen, native, multi-donor 

#358 New Fresh-frozen, native, multi-donor 

#359 New Fresh-frozen, native, multi-donor 

#360 65:#356 Fresh-frozen, native, multi-donor 

#351 63:#341, 63:#344, 64:#351 Fresh-frozen, native, multi-donor 

Individualized Report Page 12 / 14 
D14

 Set 1 of 41 

Individualized RR LXVI Report: FSV-BA

Total Lutein&Zeaxanthin, μg/mL 

Apparent Precision, SD [Analyte], μg/mL

357358359356360341344351361 

Your [Analyte], μg/mL 

Apparent Precision, SD 

Concordance, SD 

Median [Analyte], μg/mL 

Long-term Precision, SD 

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

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

1st Quartile (25%) Expectation 

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

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

Serum History Comments 

#357 New Fresh-frozen, native, multi-donor 

#358 New Fresh-frozen, native, multi-donor 

#359 New Fresh-frozen, native, multi-donor 

#360 65:#356 Fresh-frozen, native, multi-donor 

#351 63:#341, 63:#344, 64:#351 Fresh-frozen, native, multi-donor 

Individualized Report Page 13 / 14 
D15

 Set 1 of 39 

Individualized Round Robin LXVI Report: FSV-BA 

Graphical Comparability Summary
 

Total Retinol α-Tocopherol Total α-Carotene T

trans-Retinol γ/β-Tocopherol Total Lycopene Tot

Retinyl Palmitate Total β-Carotene trans-Lycopene Total L

trans-β-Carotene Total β-Cryptoxanthin Co

Individualized Report 
 

 

Appendix E. Shipping Package Inserts for RR31 

The following five items were included in each package shipped to an RR31 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
June 1, 2009 

Dear Colleague: 

UNITED STATES DEPARTMENT OF·COMMERCE 

Nation.-1 Institute of Standards and Technology 

Gaithersburg, Maryland 20899-

The samples withi,n this package constitute Vitamin C Round Robin 31 (RR31) of the 2009 Micronutrients 

Measurement Quality Assurance Program. RR.31 consists of four vials c:iffrozen serum test samples (#37, #47, 

#74,.and #114), one vial of frozen control serμm (CS #2), and 01;1e vial of ascorbic acid solid control material 

(Control). Please follow the attach~d protocols when you prepare and analyze these samples. lfyc;m cannot 

prepare the solid control solutions gravimetrically, please prepare equivalent ~olutions volumetrically an4 report 

the exact volumes used. (Routine 0.5 g gravimetric measurements are ge~erally 10-fold more accurate than routine 

0.5 mL volumetric measurements.) 

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

samples. The target value and ::::95% confidence interval for target value and ::::95% confidence interval for CS #2 

is 28.1 ±1.0 μmol/L of sample. 

The report for RR30 was e-mailed May 15, 2009. If you find your results for RR30 unsatisfactory, we recommend 

that you obtain Standard Reference Mat~rial (SRM) 970 Ascorbic Acid in Serum to validate yo.ur 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: 301-948-3 730, or e-mail: srminfo@nist.gov). 

Please be. aware that sample contact with ~y 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. 

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

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

e-mail: jbthomas@nist.gov. 

We ask that you return your results for these RR31 samples by September 28, 2009. We would appreciate 

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

confidential. · 

es rch Chemist 

Analytical Chemistry Division 

Chemical Science and Technology Laboratory 

Enclosures: Protocols, Preparation and Analysis of Control Materials !l.Ild Analysis of Test Samples 

RR31 Report Form for Ascorbic Acid Solid Control Material Preparation 

RR31 Report Form for Control Material and Test Sample Analyses 

NISI· 

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 = 29.4 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 recalibrate the wavelength and/or 

absorbance axes of your spectrophotometer and repeat the measurements. 

6)	 Measure and record the concentration of total ascorbic acid in all three dilute solutions and in the 

5% MPA Diluent in duplicate using exactly the same method that you will use for the serum 

control materials and test samples, including any enzymatic treatment. We recommend that you 

analyze these solutions in the following order: Diluent, Dilute Solution 1, Dilute Solution 2, 

Dilute Solution 3, Dilute Solution 3, Dilute Solution 2, Dilute Solution 1, Diluent. 

a)	 Compare the values of the duplicate measurements. Are you satisfied that your measurement 

precision is adequate? 

b)	 Compare the measured with the calculated [TAA] values. This is most conveniently done by 

plotting the measured values on the y-axis of a scatterplot against the calculated values on the 

x-axis. The line through the four {calculated, measured} data pairs should go through the 

origin with a slope of 1.0. Are you satisfied with the agreement between the measured and 

calculated values? 

Do not analyze the serum control materials or test samples until you are satisfied that your 

system is performing properly! 

7)	 Once you have confirmed that your system is properly calibrated, analyze the serum control 

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

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

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

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

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

measurement system may not be suitable for MPA-preserved samples; please contact us at 301­

975-3120 or jbthomas@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 31 

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 September 28, 2009 

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 31 

NIST Micronutrient Measurement Quality Assurance Program
 

Analysis of Control Materials and Test Samples
 

Sample Replicate 1 Replicate 2 Units
 

Dilute Solution 1 μmol/L of Dilute Solution 

Dilute Solution 2 μmol/L of Dilute Solution 

Dilute Solution 3 μmol/L of Dilute Solution 

5% MPA Diluent μmol/L of Diluent 

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

Serum Test Sample #37 μmol/L of Sample 

Serum Test Sample #47 μmol/L of Sample 

Serum Test Sample #74 μmol/L of Sample 

Serum Test Sample #114 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 September 28, 2009 

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 31
 

NIST Micronutrients Measurement Quality Assurance Program
 

Packing List and Shipment Receipt Confirmation Form
 

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

Label Form
 

VitC #37 Liquid frozen (1:1 serum:10% MPA) 

VitC #47 Liquid frozen (1:1 serum:10% MPA) 

VitC #74 Liquid frozen (1:1 serum:10% MPA) 

VitC #114 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 RR31 

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 30, 2009 

Dear Colleague: 

UNITED STATES DEPARTMENT OF COMMERCE 

Natiional lnadtut:a of kandarde and Technology 

Gaithersburg, Maryland 2089~ 

Enclosed is the summary report of the results for Round Robin 31 (RR3 l) 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 "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. 

RR31 consisted of four !est samples (#37, #47, #74, and #114), one serum control material 

(CS#2), and one solid control material for preparation of TAA control solutions. Details 

regarding the samples can be found in the enclosed report. 

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

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

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

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

you contact us for consultation. · 

Samples for the first vitamin Cround robin (RR32) of the 2010 NIST_Micronutrients Measurement 

Quality Assurance Program will be shipped during the week of December 7, 2009. 

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. 

I 

e i~e B. Thomas, M.B.A. 

Research Chemist 

Analytical Chemistry Division 

David L. Duewer, Ph.D 

Research Chemometrician 

Analytical Chemistry Division 

Chemical Science and Technology Laboratory Chemical Science and Technology Laboratory 

Enclosures 

Cc: L. C. Sander 

NISI 

F2
 

 

The NIST M2QAP Vitamin C Round Robin 31 (RR31) report consists of 

Page “Individualized” Report 

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

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

samples. 

2 Graphical summary of your RR31 sample measurements. 

Page “All Lab” Report 

1 A tabulation of results and summary statistics for Total Ascorbic Acid [TAA] in the RR31 

samples and control/calibration solutions. 

Serum-based Samples. One serum control and four unknowns were distributed in RR31. 

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

S31:1 Serum 37, ampouled in late 2001, previously distributed as sample S17:2 (RR17, Fall 02), 

S18:1 (RR18, Spring 03), S20:1 (RR20, Spring 04), S22:2 (RR22, Spring 05), S23:2 (RR23, 

Fall 05), S27:1 (RR27, Fall 07). 

S31:2 Serum 47, ampouled in late 2001, previously distributed as sample S18:2 (RR18, Spring 03), 

S19:3 (RR19, Fall 03), S21:3 (RR21, Fall 04), S22:3 (RR22, Spring 05) and S24:2 (RR24, 

Spring 06)., S26:2 (RR26, Spring 07) 

S31:3 SRM 970 level 1, ampouled in mid-1998 

S31:4 Serum 114, ampouled in 1995, previously distributed as sample 188a in (RR9, Summer 96) 

and 27:3 (RR27, Fall 07) 

Results. 

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

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

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

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

dL/g·cm). On the evidence of MPA density, one participant prepared the solutions in 2.5% MPA; 

this may have contributed to systematically low results for the unknowns. On the evidence of the 

maximum absorbance and calculated E1% #1, one participant had spectrophotometer issues; this had 

no impact on the [TAA] measurements. 

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

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

are linear (R2

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

-1.0 to 0.9 and slopes range from 0.96 to 1.14). 

3)	 The Measured = p+q*Median regression parameters for samples S31:1 to S31:4 (columns 23 to 26 of 

the All Lab Report) confirm the linearity of most measurement systems (R2 close to 1 and RMS close 

to 0.0). 

4)	 There is no evidence of sample degradation in any of the materials. 

5)	 The Figure below displays the interlaboratory MADe (a robust estimate of the standard deviation) as 

a function of the interlaboratory median for both the “Unkowns” and the “Controls”. The interlab 

F3
 

reproducibility precision, SDunk, for the unknowns is reasonably well described by the function 

SDunk = 1.32 + (0.080 × [TAA ])

2 . 

That is, SDunk is 1) at least 1.3 μmol/L regardless of the [TAA] and 2) at high [TAA] levels the 

relative SDunk, RSDunk, is about 8%. The SDunk is displayed as a thick black line, RSDunk is displayed 

as a blue line. Interlaboratory SD, μmol/L 

6
 

5
 

4
 

3
 

2
 

1
 

0 

Unknowns 

Controls 

15
 

10
 

5
 

0 

Relative Interlaboratory SD, % 

0 10 20 30 40 50 60 70
 

Interlaboratory Median, μmol/L
 

While there are too few data for confident assessment, the reproducibility precision for the two 

materials that have been provided as Controls, SDCS, is consistently smaller than for the Unknowns. 

It appears, therefore, that there is “room for improvement” in the interlaboratory comparability of 

[TAA] measurements. 

F4
Appendix G. “All-Lab Report” for RR31 

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 Aci

"Round Robin" 31 - Fall 2009 

Control / Calibration Samples MPA Dilute Solution 1 

Measured = a + b*Grav Density Spectrophotometry Measured, μmo

Grav, μmol/L Measured, μmol/L 

E1% Lab Date Dil:1 Dil:2 Dil:3 Dil:1 Dil:2 Dil:3 MPA Inter Slope R2 RMS g/mL CS#2 S31:1 S31:2 S3

λmax Amax 

VC-MA 10/09/09 58.8 29.6 14.8 60.2 30.0 14.9 0.0 -0.14 1.02 1.000 0.2 1.036 244. 0.5660 546.1 32.0 22.1 33.8 

VC-MB 05/08/09 58.2 28.5 14.6 60.7 30.2 15.5 0.0 0.23 1.04 1.000 0.3 1.030 243. 0.5800 565.7 28.4 23.2 35.4 

VC-MC 02/10/09 59.1 29.6 15.0 56.9 28.6 14.2 0.0 -0.06 0.96 1.000 0.1 1.016 243. 0.5663 544.0 27.5 16.7 28.5 

VC-ME 23/07/09 56.7 28.4 14.2 57.8 28.6 14.7 0.0 0.03 1.02 1.000 0.3 1.031 243. 0.5714 572.0 31.8 25.7 38.8 

VC-MG 28/08/09 62.8 31.5 16.4 64.1 31.8 16.1 0.0 -0.32 1.02 1.000 0.4 1.028 243.6 0.6100 551.3 28.0 22.1 33.7 

VC-MH 13/10/09 61.2 30.5 14.9 61.0 30.5 15.1 0.0 0.08 1.00 1.000 0.1 1.027 244.1 0.6038 560.3 28.2 21.4 32.7 

VC-MI 23/09/09 55.4 28.3 13.9 56.7 27.5 14.8 0.0 -0.06 1.02 0.999 1.0 1.030 28.4 21.5 35.3 

VC-MJ 25/09/09 59.2 30.5 15.2 67.2 33.4 15.3 0.0 -1.01 1.14 0.999 1.1 1.023 254a 0.368a 352.7a 30.1 26.0 37.8 

VC-MK 16/09/09 57.9 29.3 14.5 57.7 29.3 15.0 1.0 0.85 0.98 1.000 0.2 1.029 245. 0.1761 172.6 30.0 24.5 36.0 

VC-MN 24/09/09 63.0 31.6 15.8 62.5 30.8 14.3 0.0 -0.64 1.00 0.999 0.7 1.029 243.7 0.6178 556.7 28.7 22.1 32.7 

VC-MP 04/08/09 21.2 32.5 

VC-MU 11/09/09 25.9 18.2 31.3 

VC-NE 02/11/09 60.3 29.6 14.2 60.3 30.1 14.3 0.0 0.14 1.00 1.000 0.3 1.032 243.5 0.5950 560.1 27.9 21.5 32.1 

G2

N 10 10 10 10 10 10 10 

59.2 29.8 14.9 60.5 30.1 15.0 0.1 

2.5 1.2 0.7 3.4 1.7 0.6 0.3 

N 10 8 8 8 11 12 12 

Average Average 1.028 243.7 0.5364 508.6 29.0 22.1 34.0 

SD SD 0.005 0.7 0.1470 136.1 1.8 2.7 2.8 

Min 55.4 28.29 13.9 

58.0 28.69 14.5 

59.0 29.64 14.9 

60.7 30.53 15.1 

63.0 31.58 16.4 

2.4 1.5 0.5 

4 5 3 

56.7 27.50 14.2 0.0 

57.7 28.77 14.7 0.0 

60.4 30.09 15.0 0.0 

62.1 30.69 15.3 0.0 

67.2 33.36 16.1 1.0 

4.0 1.7 0.5 0.0 

7 6 3 

Min 1.016 243.0 0.1761 172.6 25.9 16.7 28.5 

%25 %25 1.027 243.0 0.5662 545.6 28.1 21.4 32.6 

Median Median 1.029 243.7 0.5757 554.0 28.4 22.1 33.7 

%75 %75 1.030 244.0 0.6054 561.7 30.0 23.6 35.5 

Max Max 1.036 245.0 0.6178 572.0 32.0 26.0 38.8 

MADe eSD 0.0 0.8 0.0280 13.2 1.4 1.5 2.3 

CV CV 0.22 0.33 4.9 2.4 5 7 7 

a ) 5% Trichloroacetic acid solution 

b ) Mislabeled sample 

All Lab Report 
Appendix H. Representative “Individualized Report” for RR31 

Each participant in RR31 received an “Individualized Report” reflecting their reported 

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

“VC-MA”. 

H1
 Set 1 of 16 

Vitamin C "Round Robin" 31 Report: Participant VC-MA
 

MPA Dilute Solution 1 Control/Calibration Solutions 

Density Spectrophotometry Ymeas = Inter + Slope* Xgrav 

Date RR Method 

03/20/07 26 HPLC-EC 

10/05/07 27 HPLC-EC 

03/04/08 28 HPLC-EC 

08/11/08 29 HPLC-EC 

03/03/09 30 HPLC-EC 

09/10/09 31 HPLC-EC 

g/mL 

1.033 

1.032 

1.035 

1.037 

1.037 

1.036 

λmax Amax E1% 

244.0 0.573 554.3 

242.0 0.561 557.2 

243.0 0.572 562.2 

243.0 0.567 553.2 

242.0 0.569 555.6 

244.0 0.566 546.1 

Inter Slope R2 SEE 

0.3 1.00 1.000 0.31 

-0.1 0.99 1.000 0.14 

0.7 1.03 0.999 0.99 

0.3 1.03 1.000 0.64 

0.2 1.03 1.000 0.40 

-0.1 1.02 1.000 0.20 

Mean 1.035 243.0 0.57 554.8 Pooled SEE 0.53 

SD 0.002 0.9 0.00 5.3 

CV 0.18 0.37 0.8 0.9 

[TAA] mmol/Lsample 

7 34.9 0.3 1.1 

12 8.2 0.3 0.5 

Date RR Sample 

10/17/05 23 CS#2 

03/09/06 24 CS#2 

08/28/06 25 CS#2 

10/05/07 27 CS#2 

08/11/08 29 CS#2 

09/10/09 31 CS#2 

03/20/03 18 S18:2 

11/13/03 19 S19:3 

09/13/04 21 S21:3 

03/08/05 22 S22:3 

03/09/06 24 S24:2 

03/20/07 26 S26:2 

09/10/09 31 S31:2 

09/23/98 11 S11:1:A 

04/02/99 12 S12:1:A 

09/17/01 13 S13:1 

09/27/01 14 S14:3 

09/18/01 15 S15:1 

11/18/02 16 S16:1 

11/13/03 19 S19:4 

02/23/04 20 S20:3 

10/17/05 23 S23:4 

08/28/06 25 S25:1 

08/11/08 29 S29:2 

09/10/09 31 S31:3 

06/19/96 09 S09:2 

Rep1 Rep2 Fadj Mean SDdup 

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 

28.1 27.4 1.0 27.7 0.5 

27.2 27.2 1.0 27.2 0.0 

31.8 32.2 1.0 32.0 0.3 

N Mean SDrepeat SDreprod 

6 28.9 0.5 1.8 

35.1 36.0 1.0 35.6 0.6 

35.9 35.8 1.0 35.9 0.1 

33.2 32.9 1.0 33.0 0.2 

35.7 35.6 1.0 35.6 0.1 

35.8 35.5 1.0 35.6 0.2 

35.0 35.4 1.0 35.2 0.3 

33.9 33.7 1.0 33.8 0.2 

15.5 13.9 0.5 7.4 0.6 

14.5 15.8 0.5 7.6 0.5 

8.4 8.5 1.0 8.5 0.1 

8.0 7.7 1.0 7.8 0.2 

8.9 8.7 1.0 8.8 0.1 

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 

8.3 8.4 1.0 8.3 0.1 

7.3 8.1 1.0 7.7 0.5 

51.7 51.1 0.5 25.7 0.2 

28.5 28.6 1.0 28.5 0.1 

29.0 29.9 1.0 29.4 0.7 

3 27.9 0.4 2.0 

10/05/07 27 S27:3 

09/10/09 31 S31:4 

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

Micronutrients Measurement Quality Assurance Program 

National Institute of Standards and Technology 

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

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

Individualized Report Page 1 / 2 

H2
 

NIST, RR 22

H3

 Set 1 of 16 

Vitamin C "Round Robin" 31 Report: Participant VC-MA 

Total Ascorbic Acid, μmol/mL 

[Total Ascorbic Acid], μmol/L 

S17:2S18:1 S20:1S22:2 S23:2 S27:1 S31:1 S18:2 S19:3 S21:3 S22:3 Apparent Precision, SD S24:2 S26:2S31:2S11:1S12:1S13:1S14:3S15:1S16:1S19:4 S20:3S23:4 S25:1 S29:2 S31:3 S09:2 S27:3 S31:4 

Your [Total Ascorbic Acid], μmol/L 

Median [Total Ascorbic Acid], μmol/L 

Concordance, SD 

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

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

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

Sample Comments 

S31:1 VitC #37 previously distributed in RRs 17, 18, 20, 22, 23, 27 

S31:2 VitC #47, previously distributed in RRs 18, 19, 21, 22, 24, 26 

S31:3 VitC #74, previously distributed in RRs 11, 12, 13, 14, 15, 16, 19, 20, 23, 25, 29 

S31:4 VitC #114, previously distributed in RRs 9, 27 

Individualized Report 2 / 2