NISTIR 7880-1

NIST Micronutrients Measurement 

Quality Assurance Program 

Summer 2012 

Comparability Studies 

Results for Round Robin LXXII 

Fat-Soluble Vitamins and Carotenoids in Human Serum 

and Round Robin 37 Ascorbic Acid in Human Serum 

David L. Duewer 

Jeanice B. Thomas 

http://dx.doi.org/10.6028/NIST.IR.7880-1 
 

 

 

NISTIR 7880-1
 

NIST Micronutrients Measurement 

Quality Assurance Program 

Summer 2012 

Comparability Studies 

Results for Round Robin LXXII 

Fat-Soluble Vitamins and Carotenoids in Human Serum 

and Round Robin 37 Ascorbic Acid in Human Serum 

David L. Duewer 

Jeanice B. Thomas 

Chemical Sciences Division 

Materials Measurement Laboratory 

http://dx.doi.org/10.6028/NIST.IR.7880-1 

March, 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 2012 MMQAP measurement comparability improvement studies: 1) Round Robin LXXII 

Fat-Soluble Vitamins and Carotenoids in Human Serum and 2) Round Robin 37 Total Ascorbic Acid 

in Human Serum. The materials for both studies were shipped to participants in June 2012; 

participants were requested to provide their measurement results by September 28, 2012. 

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

Round Robin 37: Vitamin C in Human Serum............................................................................... 2
 

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

Appendix A. Shipping Package Inserts for RR72........................................................................ A1
 

Appendix B. Final Report for RR72 ..............................................................................................B1
 

Appendix C. All-Lab Report for RR72 ..........................................................................................C1
 

Appendix D. Representative Individualized Report for RR72 ................................................... D1
 

Appendix E. Shipping Package Inserts for RR37 ......................................................................... E1
 

Appendix F. Final Report for RR37............................................................................................... F1
 

Appendix G. “All-Lab Report” for RR37..................................................................................... G1
 

Appendix H. Representative “Individualized Report” for RR37............................................... 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 LXXII: Fat-Soluble Vitamins and Carotenoids in Human Serum 

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

LXXII comparability study (hereafter referred to as RR72) received one lyophilized and four liquidfrozen human serum test samples for analysis. Unless multiple vials were previously requested, 

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

June 2012. 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 RR72 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 All-Lab 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 the Individualized Report 

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

Appendix D. 

Round Robin 37: Vitamin C in Human Serum 

Participants in the MMQAP Vitamin C in Human Serum Round Robin 37 comparability study 

(hereafter referred to as RR37) 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 2012. 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 RR37 consists of three documents: 

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

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

reproduced as Appendix F. 

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

several consensus statistics. This All-Lab Report is reproduced as Appendix G. 

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

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

used in the Individualized Report are described in detail elsewhere [3]. An example 

Individualized Report is reproduced as Appendix H. 

2
 
 

References 

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

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

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

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

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

Stability, Intralaboratory Repeatability, and Interlaboratory Reproducibility. Clin Chem 

1996;42(8):1257-1262. 

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

Measurement Quality Assurance Program: Helping Participants Use Interlaboratory Comparison 

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

1999;71(9):1870-1878. 

3
 
 

Appendix A. Shipping Package Inserts for RR72 

The following three items were included in each package shipped to an RR72 participant: 

• Cover letter 

• Datasheet 

• Packing List and Shipment Receipt Confirmation Form 

The cover letter and datasheet were enclosed in a sealed waterproof bag along with the samples 

themselves. The packing list was placed at the top of the shipping box, between the cardboard 

covering and the foam insulation. 

A1
June 25, 2012 

Dear Colleague: 

UNITED STATES DEPARTMENT OF COMMERCE 

National Institute of Standards and Technology 

Gaithersburg, Maryland 20899-

Enclosed are samples for the second fat-soluble vitamins and carotenoids in semm study Round 

Robin LXXII (RR72) for the 2012 NIST Micronutrients Measurement Quality Assurance 

Program. The set of samples (Sera 387- 391) consists of one vial of lyophilized serum and one 

vial each of four 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, 2012. Results received 

more than two weeks after the due date may not be included in the summary report for RR72. 

The feedback report concerning the study will be distributed in November 2012. 

Samples should be allowed to stand at 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 run (ethanol); retinyl palmitate, 975 at 325 run (ethanol); cx.-tocopherol, 75.8 

at 292 run (ethanol); y-tocopherol, 91.4 at 298 run (ethanol); cx.-carotene, 2800 at 444 run 

(hexane); P-carotene, 2560 at 450 run (ethanol), 2592 at 452 run (hexane); and lycopene, 3450 at 

472 run (hexane). 

Please report your results for RR72 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 oremail me atjbthomas@nist.gov. 

Je nice Brown Thomas 

ogram Coordinator/Research Chemist 

Analytical Chemistry Division 

Material Measurement Laboratory 

A2

NISI 
Participant #: ________ Date: _____________ 

Round Robin LXXII: Human Sera 

NIST Micronutrients Measurement Quality Assurance Program 

Analyte 387 388 389 390 391 Units* 

total retinol 

trans-retinol 

retinyl palmitate 

-tocopherol 

-tocopherol 

-tocopherol 

total -carotene 

trans--carotene 

total cis--carotene 

total -carotene 

total lycopene 

trans-lycopene 

total -cryptoxanthin 

total -cryptoxanthin 

total lutein 

total zeaxanthin 

total lutein&zeaxanthin

 total coenzyme Q10 

ubiquinol (QH2) 

ubiquinone (Qox) 

phylloquinone (K1) 

25-hydroxyvitamin D 

Phytoene 

Phytofluene 

* we prefer g/mL

Were the samples frozen when received? Yes | No 

Comments: 

Mail: M2QAP Please return results by 

NIST, Stop 8392 28-Sep-2012 Fax: 301-977-0685 

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

A3
 

 

 

 

Participant #: ________ Date: _____________ 

Fat-Soluble Vitamins Round Robin LXXII
 

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 

#387 Lyophilized Yes 2 mL amber, red cap 

#388 Liquid frozen No 2 mL amber, green cap 

#389 Liquid frozen No 2 mL amber, red cap 

#390 Liquid frozen No 2 mL amber, gold cap 

#391 Liquid frozen No 2 mL amber, green 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 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 RR72 

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
November 30, 2012 

Dear Colleague: 

UNITED STATES DEPARTMENT OF COMMERCE 

National Institute af Standards and Technalagy 

Gaithersburg, Maryland 20899-

Enclosed is the summary report of the results for round robin LXXII (RR72) of the 2012 NIST 

Micronutrients Measurement Quality Assurance Program (M2

QAP) for the fat-soluble vitamins and 

carotenoids in human serum. Included in this report are: 1) a summary of data and measurement 

comparability scores for all laboratories, 2) a detailed graphical analysis of your results; and 3) a 

graphical summary of your measurement comparability. RR72 (Sera 387 - 391) consisted of one vial of 

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

can be found in the enclosed report. 

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

Lab Report. Combined results rated 1 to 3 are within 1 to 3 standard deviations of the assigned value, 

respectively; those rated 4 are >3 standard deviations from the assigned value. Similar information is 

presented graphically in the "target plots" that are the last page of your Individualized Report. If you 

have concerns regarding your laboratory's performance, please contact us for consultation. 

Samples for the first set of fat-soluble vitamins and carotenoids in serum interlaboratory exercise (RR73) 

of the 2013 M2QAP will be shipped starting January 22, 2013. Please contact us immediately if this 

schedule is problematic for your laboratory. 

If you have questions or concerns regarding this report, please contact David Duewer at 301-975-3935; email: david.duewer@nist.gov or me at 301-975-3120; e-mail: jbthomas@nist.gov; or fax: 301-977-0685. 

Sincerely, 

Je i Brown 

~04rnlP Thomas, M.B.A. 

Re arch Chemist 

Chemical Sciences Division 

Material Measurement Laboratory 

Enclosures 

Cc: L.C. Sander 

David L. Duewer, Ph.D. 

Research Chemometrician 

Chemical Sciences Division 

Material Measurement Laboratory 

B2

NISI 
 

 

 

 

 

 

 

 

The NIST MMQAP Round Robin LXXII (RR72) report consists of: 

Page 

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

5 A listing of the analytes reported by only one participant and 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 

387 

388 

389 

390 

391 

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 eight other participants. 

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

 Five samples were distributed in RR72. 

Description 

Lyophilized, native serum prepared in 1999. Serum 

#380 is the liquid-frozen partner of this sample. 

Liquid-frozen, native serum prepared in 1999. Serum 

#377 is the lyophilized partner of this sample. 

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

This is Level I of SRM 968e. 

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

2011. This material was designed to have low contents 

of α- and β-carotene and lycopene but a high content of 

β-cryptoxanthin.. 

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

Prior Distributions 

#270:RR49-3/01, #276:RR50-9/01, 

#367:RR68-9/10, #377:RR70-9/11 

#267:RR49-9/00, #274:RR50-9/01, 

#368:RR68-9/10, #380:RR70-9/11 

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

#375:RR69-3/11 

#383:RR71 

#356:RR65-3/09, #360:RR66-9/09 

1)	 SRM 968e Stability. There was no significant change in the median level or measurement variability 

of any measurand in the SRM 968e Level I material. 

2)	 Lyophilized vs Liquid-frozen Stability. After 13 years, there is no change in the median level or the 

measurement variability in any analyte in the lyophilized #387 material or the #388 liquid-frozen 

material prepared from the same serum pool. The analyte levels in the lyophilized material are 

slightly lower than in the liquid-frozen material due to reconstituting with 1.0 ml water rather than 

reconstituting to a total volume of 1.0 ml. 

B3
Appendix C. All-Lab Report for RR72 

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. 

C1
Round Robin LXXII Laboratory Results 

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

Lab 387 388 389 390 391 

C2

FSV-BA 0.664 0.711 0.374 0.487 0.774 

FSV-BB 0.651 0.664 0.360 0.465 0.806 

FSV-BC 0.621 0.672 0.401 0.484 0.752 

FSV-BD 0.668 0.687 0.366 0.461 0.746 

FSV-BE 0.550 0.580 0.310 0.400 0.630 

FSV-BF 0.600 0.760 0.400 0.480 0.790 

FSV-BG 0.658 0.700 0.360 0.467 0.768 

FSV-BJ 0.650 0.681 0.373 0.454 0.744 

FSV-BK 0.660 0.636 0.362 0.439 0.755 

FSV-BL 0.570 0.630 0.340 0.430 0.720 

FSV-BM 0.620 0.620 0.360 0.440 0.720 

FSV-BN 0.660 0.690 0.370 0.490 0.650 

FSV-BO 0.530 0.610 0.300 0.370 0.660 

FSV-BQ 0.700 0.740 0.380 0.510 0.790 

FSV-BR 0.660 0.640 0.350 0.430 na
 

FSV-BS
 ≥0.534 ≥0.542 ≥0.281 ≥0.374 ≥0.629 

FSV-BU 0.725 0.754 0.391 0.475 0.806 

FSV-BV 0.732 0.731 0.406 0.518 0.722 

FSV-BW 0.630 0.650 0.340 0.450 0.740 

FSV-CC 0.638 0.678 0.358 0.448 0.743 

FSV-CE 0.531 0.670 0.361 0.464 0.676 

FSV-CG 0.691 0.699 0.395 0.498 0.790 

FSV-CI 0.654 0.672 0.353 0.433 0.746 

FSV-CZ 0.665 0.720 0.390 0.485 0.742 

FSV-DD 0.660 0.690 0.360 0.470 0.700 

FSV-DV 0.668 0.783 0.392 0.542 0.826 

FSV-EE 

FSV-FK 0.607 0.626 0.335 0.441 0.706 

FSV-FZ 0.644 0.657 0.354 0.450 0.746 

387 388 389 390 391 

0.534 0.542 0.281 0.374 0.629 

0.632 0.676 0.358 0.444 0.737 

387 388 389 390 391 

0.022 0.020 0.016 0.016 0.044 

0.024 0.020 0.009 0.008 0.035 

0.017 0.022 0.014 0.015 0.044 

0.020 0.019 0.005 0.013 0.053 

0.020 0.022 0.012 0.013 0.048 

387 388 389 390 391 

5.89 6.19 6.66 6.72 10.35 

6.20 6.58 6.92 7.34 10.50 

5.60 6.70 7.10 6.50 10.00 

5.60 5.90 6.30 6.40 10.00 

5.70 6.70 7.00 6.90 10.80 

5.85 6.20 6.35 6.45 10.42 

5.68 6.01 6.64 6.49 10.06 

6.10 6.30 6.42 6.59 10.28 

6.00 6.50 6.90 6.90 10.20 

6.70 6.90 7.00 7.40 10.60 

5.80 6.02 6.07 6.50 9.67 

5.47 6.16 6.12 6.16 9.91 

7.00 8.00 8.00 8.00 11.00 

6.40 6.70 7.13 6.70 9.90 

6.93 7.29 7.71 8.49 12.59 

6.67 6.00 6.16 6.96 9.11 

6.20 6.60 7.20 7.25 10.53 

6.22 6.60 6.98 6.85 10.96 

7.30 5.58 5.77 7.34 11.30 

6.08 6.47 6.90 6.96 10.89 

5.61 5.81 6.29 6.66 9.92 

6.38 6.69 7.13 7.28 11.49 

5.10 6.30 5.50 7.20 8.60 

7.30 7.50 8.00 8.10 12.10 

6.73 6.87 7.57 7.86 11.53 

N 27 27 27 27 26 2 2 2 2 2 5 5 5 5 5 25 25 25 25 25 

Min 0.530 0.580 0.300 0.370 0.630 0.534 0.542 0.281 0.374 0.629 0.017 0.019 0.005 0.008 0.035 5.10 5.58 5.50 6.16 8.60 

Median 0.654 0.678 0.361 0.464 0.745 0.583 0.609 0.319 0.409 0.683 0.020 0.020 0.012 0.013 0.044 6.10 6.50 6.90 6.90 10.42 

Max 0.732 0.783 0.406 0.542 0.826 0.632 0.676 0.358 0.444 0.737 0.024 0.022 0.016 0.016 0.053 7.30 8.00 8.00 8.49 12.59 

SD 0.024 0.049 0.019 0.034 0.040 0.002 0.002 0.005 0.003 0.006 0.62 0.46 0.71 0.59 0.73 

CV 4 7 5 7 5 11 9 41 23 13 10 7 10 9 7 

Npast 35 37 32 31 30 12 12 7 0 5 10 10 8 5 9 38 39 33 29 32 

Medianpast 0.636 0.665 0.357 0.460 0.740 0.617 0.657 0.347 0.692 0.021 0.024 0.010 0.019 0.045 5.97 6.35 6.78 7.15 10.56 

SDpast 0.048 0.058 0.032 0.022 0.061 0.040 0.048 0.035 0.097 0.009 0.011 0.005 0.012 0.009 0.51 0.62 0.49 0.67 0.80 

NAV 0.654 0.678 0.361 0.464 0.745 0.020 0.020 0.012 0.013 0.044 6.10 6.50 6.90 6.90 10.42 

NAU 0.052 0.054 0.030 0.037 0.059 0.011 0.011 0.011 0.011 0.015 0.62 0.56 0.71 0.59 0.81 

All Lab Report 
Round Robin LXXII Laboratory Results 

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

C3

Lab 387 388 389 390 391 387 388 389 390 391 387 388 389 390 391 387 388 389 390 391 

FSV-BA 0.101 0.110 0.094 0.075 0.271 0.459 0.496 0.090 0.043 0.278 0.440 0.475 0.083 0.042 0.262 0.019 0.022 0.007 0.001 0.016 

FSV-BB 0.109 0.117 0.100 0.059 0.265 0.462 0.496 0.096 0.056 0.290 0.424 0.455 0.080 0.041 0.230 0.019 0.019 0.006 0.003 0.015 

FSV-BC 

FSV-BD 

FSV-BE 0.620 0.580 0.110 0.050 0.340 

FSV-BF 0.534 0.593 0.075 0.037 0.272 

FSV-BG 0.514 0.541 0.089 0.042 0.277 

FSV-BJ 0.457 0.495 0.094 0.054 0.254 

FSV-BK 

FSV-BL 

FSV-BM 

FSV-BN 0.514 0.536 0.086 0.047 0.259 

FSV-BO 0.473 0.546 0.114 0.066 0.311 

FSV-BQ 

FSV-BR 

FSV-BS ≥0.607 ≥0.435 ≥0.106 ≥0.029 ≥0.111 0.607 0.435 0.106 0.029 0.111 

FSV-BU 0.406 0.403 0.081 0.040 0.228 

FSV-BV 0.482 0.485 0.088 0.052 0.274 

FSV-BW 0.505 0.509 0.082 0.039 0.228 

FSV-CC 

FSV-CE 0.808 0.465 0.078 0.063 0.336 

FSV-CG 0.188 0.189 0.164 0.255 0.179 0.442 0.469 0.087 0.043 0.269 0.416 0.444 0.082 0.040 0.252 0.026 0.025 nq nq 0.017 

FSV-CI 0.564 0.559 0.099 0.050 0.321 

FSV-CZ 0.382 0.407 0.072 0.068 0.220 

FSV-DD 

FSV-DV 

FSV-EE 

FSV-FK 

FSV-FZ 

N 

Min 

Median 

Max 

SD 

CV 

Npast 

Medianpast 

SDpast 

NAV 

NAU 

3 3 3 3 3 

0.101 0.110 0.094 0.059 0.179 

0.109 0.117 0.100 0.075 0.265 

0.188 0.189 0.164 0.255 0.271 

6 6 5 4 5 

0.101 0.109 0.110 0.063 0.261 

0.040 0.101 0.025 0.043 0.026 

15 

0.382 

0.482 

0.808 

0.047 

10 

26 

0.484 

0.063 

15 

0.403 

0.496 

0.593 

0.059 

12 

27 

0.512 

0.067 

15 

0.072 

0.088 

0.114 

0.010 

11 

22 

0.091 

0.014 

15 

0.037 

0.050 

0.068 

0.010 

21 

18 

0.047 

0.009 

15 

0.220 

0.274 

0.340 

0.030 

11 

21 

0.274 

0.034 

4 4 4 4 4 

0.416 0.435 0.080 0.029 0.111 

0.432 0.450 0.083 0.041 0.241 

0.607 0.475 0.106 0.042 0.262 

0.018 0.015 0.003 0.001 0.023 

4 3 3 4 10 

10 11 8 5 8 

0.436 0.471 0.083 0.044 0.247 

0.037 0.038 0.006 0.004 0.012 

3 3 2 2 3 

0.019 0.019 0.006 0.001 0.015 

0.019 0.022 0.006 0.002 0.016 

0.026 0.025 0.007 0.003 0.017 

8 8 5 0 6 

0.025 0.024 0.005 0.014 

0.007 0.007 0.003 0.002 

0.109 0.117 0.100 0.075 0.265 0.482 0.496 0.088 0.050 0.274 

0.067 0.069 0.016 0.011 0.040 

0.432 0.450 0.083 0.041 0.241 0.019 0.022 0.016 

All Lab Report 
 

Round Robin LXXII Laboratory Results 

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

C4

Lab 387 388 389 390 391 387 388 389 390 391 387 388 389 390 391 387 388 389 

FSV-BA 0.205 0.202 0.151 0.318 0.188 0.135 0.113 0.080 0.183 0.123 0.060 0.057 0.182 0.076 0.050 0.033 0.022 0.023 

FSV-BB 0.218 0.199 0.164 0.303 0.199 0.125 0.099 0.072 0.156 0.114 0.048 0.046 0.153 0.054 0.045 0.023 0.016 0.022 

FSV-BC 

FSV-BD 

FSV-BE 

FSV-BF 

FSV-BG 0.245 0.222 0.190 0.367 0.237 0.152 0.116 0.086 0.194 0.138 0.056 0.056 0.186 0.068
 0.053 

FSV-BJ
 0.270 0.225 0.200 0.415 0.238 nq nq nq 0.107 0.046 

FSV-BK 

FSV-BL 

FSV-BM 

FSV-BN 0.267 0.230 0.195 0.385 0.254 0.052 0.052 0.164 0.055 0.049 

FSV-BO 0.175 0.174 0.140 0.283 0.171 0.051 0.049 0.164 0.060 0.048 

FSV-BQ 

FSV-BR 

FSV-BS 0.186 0.221 0.077 0.140 0.252 0.065 0.088 0.043 0.061 0.082 0.064 0.073 0.082 0.048 0.080 

FSV-BU 0.214 0.194 0.177 0.349 0.205 0.064 0.071 0.189 0.070 0.060 

FSV-BV 0.214 0.216 0.192 0.351 0.222 0.044 0.044 0.188 0.055 0.044 

FSV-BW 0.257 0.216 0.177 0.413 0.274 

FSV-CC 

FSV-CE 

FSV-CG 0.240 0.236 0.185 0.390 0.230 0.144 0.121 0.086 0.205 0.134 0.067 0.068 0.201 0.085 0.063 

FSV-CI 

FSV-CZ 

FSV-DD 

FSV-DV 

FSV-EE 

FSV-FK 

FSV-FZ 

N 11 11 11 11 11 5 5 5 5 5 9 9 9 10 10 2 2 2 

Min 0.171 0.175 0.174 0.077 0.140 0.082 0.065 0.088 0.043 0.061 0.044 0.044 0.044 0.082 0.046 0.022 0.023 0.016 

Median 0.230 0.218 0.216 0.177 0.351 0.123 0.135 0.113 0.080 0.183 0.050 0.056 0.056 0.173 0.058 0.023 0.028 0.019 

Max 0.274 0.270 0.236 0.200 0.415 0.138 0.152 0.121 0.086 0.205 0.080 0.067 0.073 0.201 0.085 0.023 0.033 0.022 

SD 0.036 0.040 0.021 0.022 0.058 0.016 0.014 0.011 0.009 0.033 0.006 0.012 0.015 0.023 0.015 

CV 15 18 10 12 16 13 10 10 11 18 12 21 26 13 26 

Npast 21 22 17 13 16 10 10 8 6 8 21 22 17 14 17 5 5 4 

Medianpast 0.224 0.233 0.226 0.171 0.376 0.124 0.138 0.116 0.083 0.180 0.047 0.050 0.050 0.163 0.059 0.023 0.027 0.018 

SDpast 0.032 0.037 0.032 0.036 0.046 0.023 0.018 0.018 0.019 0.021 0.011 0.010 0.011 0.048 0.009 0.006 0.005 0.003 

NAV 

NAU 

0.230 0.218 0.216 0.177 0.351 0.123 0.135 0.113 0.080 0.183 0.050 0.056 0.056 0.173 0.058 

0.055 0.053 0.052 0.045 0.078 0.021 0.024 0.020 0.014 0.033 0.012 0.013 0.015 0.036 0.015 

All Lab Report 
 

Round Robin LXXII Laboratory Results 

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

C5

Lab 387 388 389 390 391 387 388 389 390 391 387 388 389 390 391 387 388 389 390 391 3

FSV-BA 0.121 0.121 0.097 0.113 0.100 

FSV-BB 0.120 0.098 0.107 0.106 0.115 0.055 0.050 0.066 0.053 0.054 0.170 0.175 0.147 0.173 0.160 

FSV-BC 

FSV-BD 

FSV-BE 0.91 0.900 1.16 0.86 0.930 2.

FSV-BF 

FSV-BG 0.123 0.131 0.104 0.110 0.100
 

FSV-BJ
 0.086 0.080 0.089 0.081 0.078 0.86 0.910 1.04 0.95 0.760 

FSV-BK 

FSV-BL 

FSV-BM 

FSV-BN 0.130 0.128 0.159 0.185 0.091 

FSV-BO 0.100 0.095 0.105 0.084 0.093 0.029 0.015 0.015 0.019 0.027 0.47 0.768 0.94 0.58 0.553 

FSV-BQ 

FSV-BR 

FSV-BS 

0.120 0.129 0.110 0.120 0.103 

0.110 0.153 0.058 0.051 0.126 0.060 0.053 0.057 0.053 0.065 0.191 0.170 0.206 0.115 0.104 

FSV-BU 0.132 0.146 0.139 0.113 0.099 0.67 0.840 0.92 0.91 0.720 

FSV-BV 0.124 0.127 0.109 0.146 0.076 

FSV-BW 0.97 0.910 1.37 0.81 0.780 

FSV-CC 

FSV-CE 

FSV-CG 0.146 0.156 0.149 0.172 0.136
 

FSV-CI
 0.066 0.066 0.073 0.054 0.069 0.032 0.026 0.031 0.018 0.026 0.83 0.840 1.09 0.81 0.800 

1.

FSV-CZ 

0.095 0.098 0.092 0.104 0.072 

1.28 0.881 1.14 1.08 1.207 

FSV-DD 

FSV-DV 

FSV-EE 0.68 1.436 0.88 0.67 0.823 

FSV-FK 

FSV-FZ 

N 5 5 5 5 5 4 4 4 4 4 10 10 10 10 10 8 8 8 8 8 

Min 0.069 0.066 0.066 0.058 0.051 0.026 0.029 0.015 0.015 0.018 0.095 0.098 0.092 0.104 0.072 0.553 0.47 0.768 0.88 0.58 1.

Median 0.093 0.100 0.095 0.089 0.081 0.041 0.044 0.038 0.044 0.036 0.127 0.130 0.125 0.118 0.100 0.790 0.85 0.891 1.07 0.84 2.

Max 0.126 0.120 0.153 0.107 0.106 0.065 0.060 0.053 0.066 0.053 0.191 0.175 0.206 0.185 0.160 1.207 1.28 1.436 1.37 1.08 2.

SD 0.033 0.021 0.022 0.024 0.038 0.021 0.020 0.020 0.026 0.025 0.010 0.018 0.035 0.016 0.010 0.076 0.22 0.052 0.16 0.14 

CV 36 21 23 27 46 51 45 53 59 71 8 14 28 13 10 10 26 6 15 17 

Npast 11 12 9 4 9 10 11 8 0 8 20 21 18 14 17 8 10 8 9 6 

Medianpast 0.086 0.088 0.072 0.097 0.060 0.034 0.036 0.034 0.029 0.122 0.127 0.107 0.131 0.097 0.814 0.80 0.857 1.08 0.92 

SDpast 0.020 0.016 0.015 0.028 0.010 0.012 0.013 0.009 0.015 0.022 0.024 0.013 0.041 0.020 0.156 0.16 0.073 0.06 0.15 

NAV 

NAU 

0.093 0.100 0.095 0.089 0.081 0.041 0.044 0.038 0.044 0.036 0.127 0.130 0.125 0.118 0.100 0.790 0.85 0.891 1.07 0.84 

0.033 0.021 0.022 0.024 0.038 0.026 0.027 0.035 0.024 0.021 0.079 0.22 0.089 0.16 0.14 

All Lab Report 
 

 

 

 

 

 

Round Robin LXXII Laboratory Results 

Analytes Reported By One Laboratory 

Analyte Lab 387 388 389 390 391 

25-hydroxyvitamin D FSV-BN 0.0021 0.0040 0.0054 0.0063 0.0047 

Phytoene FSV-BS nd nd nd 0.089 0.081 

Phytofluene FSV-BS 0.123 0.119 0.132 0.110 0.116 

Term 

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

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) 

NAV NIST Assigned Value

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

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

NAU NIST Assigned Uncertainty: √(S 2

 + Sbtw 2)

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

 deviation between Median and NIST. 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 

Legend 

All Lab Report 

C6

Page 5 / 6 
 

 

 

 

 

 

Lab 

FSV-BA 

FSV-BB 

FSV-BC 

FSV-BD 

FSV-BE 

FSV-BF 

FSV-BG 

FSV-BJ 

FSV-BK 

FSV-BL 

FSV-BM 

FSV-BN 

FSV-BO 

FSV-BQ 

FSV-BR 

FSV-BS 

FSV-BU 

FSV-BV 

FSV-BW 

FSV-CC 

FSV-CE 

FSV-CG 

FSV-CI 

FSV-CZ 

FSV-DD 

FSV-DV 

FSV-FK 

FSV-FZ 

n 

Round Robin LXXII Laboratory Results 

Comparability Summary 

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

1 1 1 1 1 1 1 1 

1 1 1 1 1 1 1 1 2 

1 

1 1 

2 1 1 2 

2 1 2 

1 1 1 1 1 1 1 1 

1 1 1 1 1 2 1 

1 1 

2 1 

1 1 

1 1 1 2 1 1 2 

3 1 1 2 1 1 1 1 1 

1 2 

1 1 

3 3 4 2 2 2 2 

2 3 1 2 1 1 1 1 

2 2 1 1 1 1 1 1 

1 1 4 1 1 1 

1 1 

2 2 3 

1 1 2 1 1 1 2 2 

1 1 1 1 2 2 2 

1 1 1 2 

1 

2 2 

1 2 

1 2 3 

28 25 13 16 11 11 10 5 10 

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) summarizes your measurement 

performance for a given analyte relative to the consensus 

medians in this study. CS is the average distance (in units of 

standard deviation) of your measurement performance 

characteristics from the consensus performance. CS is 

calculated when the number of quantitative values you reported, 

Nyou, is at least two and at least six participants reported 

quantitative values for the analyte. 

We define CS as follows: 

MINIMUM 4,INTEGER 1 

you Youi Median i 

NAU i 

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

∑ 

= 





 N 

i 1 

% 2 25 24 8 31 18 9 30 40 50 

CS = 2 2 + C + AP 



 



 % 1 68 72 77 56 73 91 70 60 50 

% 3 7 4 8 13 0 0 0 0 0 

% 4 0 0 8 0 9 0 0 0 0 C = Concordance = 

Nyou 



 





N 

Youi 

NAU 

− 

AP = Apparent Precision = 

i 

1 

Median 

i 

− 



 



 

NAU = NIST Assigned Uncertainty 

you 

For further details, please see 

1i 

you

∑ 

= 

N 2

Duewer DL, Kline MC, Sharpless KE, Brown Thomas J, Gary 

KT. Micronutrients Measurement Quality Assurance 

Program: Helping participants use interlaboratory comparison 

exercise results to improve their long-term measurement 

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

All Lab Report 

C7

Page 6 / 6 
 

Appendix D. Representative Individualized Report for RR72 

Each participant in RR72 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 RR72: 

• Total Retinol 

• Retinyl Palmitate 

• α-Tocopherol 

• γ/β-Tocopherol 

• Total β-Carotene 

• Total α-Carotene 

• Total Lycopene 

• trans-Lycopene 

• Total β-Cryptoxanthin 

• Total Lutein 

• Total Lutein & Zeaxanthin 

• Coenzyme Q10 

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

participant FSV-BA. 

D1
 

 Set 1 of 33 

Individualized Round Robin LXXII Report: FSV-BA 

Summary 

Serum 387 Serum 388 Serum 389 Serum 390 S

D2

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

Total Retinol 0.664 0.654 27 0.711 0.678 27 0.374 0.361 27 0.487 0.464 27 0.77

Retinyl Palmitate 0.02 0.02 5 0.0 0.0 5 0.0 0.0 5 0.02 0.01 5 0.04 

α-Tocopherol 5.89 6.10 25 6.19 6.50 25 6.66 6.90 25 6.72 6.90 25 10.35 

γ/β-Tocopherol 2.300 2.235 13 2.438 2.290 13 1.901 1.794 13 1.831 1.750 13 2.56

δ-Tocopherol 0.101 0.109 3 0.110 0.117 3 0.094 0.100 3 0.075 0.075 3 0.27

Total β-Carotene 0.459 0.482 15 0.496 0.496 15 0.090 0.088 15 0.043 0.050 15 0.27

trans-β-Carotene 0.440 0.432 4 0.475 0.450 4 0.083 0.083 4 0.042 0.041 4 0.26

Total cis-β-Carotene 0.019 0.019 3 0.022 0.022 3 0.007 2 0.001 2 0.01

Total α-Carotene 0.016 0.022 11 0.020 0.020 11 0.006 0.007 11 0.010 0.014 11 0.04

Total Lycopene 0.188 0.230 11 0.205 0.218 11 0.202 0.216 11 0.151 0.177 11 0.31

trans-Lycopene 0.123 0.123 5 0.135 0.135 5 0.113 0.113 5 0.080 0.080 5 0.18

Total β-Cryptoxanthin 0.050 0.050 9 0.060 0.056 9 0.057 0.056 9 0.182 0.173 10 0.07

Total α-Cryptoxanthin 0.023 2 0.033 2 0.022 2 0.027 2 0.02

Total Lutein&Zeaxanthin 0.121 0.127 10 0.121 0.130 10 0.097 0.125 10 0.113 0.118 10 0.10

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

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

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

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

Micronutrients Measurement Quality Assurance Program 

National Institute of Standards and Technology Tel: (3

100 Bureau Drive Stop 8392 Fax: (3

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

Individualized Report 
 

 Set 1 of 33 

Individualized RR LXXII Report: FSV-BA

Total Retinol, μg/mL Your [Analyte], μg/mL 

Median [Analyte], μg/mL 

270276367377387267274368380388357365375389383390356360391 

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%) 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. 

erum Comments History 

387 Lyophilized, same native pool as #388 49#270, 50#276, 68#367, 70#377 

388 Fresh-frozen, same native pool as #387 49#267, 50#274, 68#368, 70#380 

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

390 Fresh-frozen, native, single-donor 71#383 

391 Fresh-frozen, native, multi-donor 65#356, 66#360 

Individualized Report ILR_RR72_FSV-BA.xlsx, Page 2 / 12 

D3
 

 Set 1 of 33 

Individualized RR LXXII Report: FSV-BA

Retinyl Palmitate, μg/mL Your [Analyte], μg/mL 

Median [Analyte], μg/mL 

270276367377387267274368380388357365375389383390356360391 

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%) 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. 

erum Comments History 

387 Lyophilized, same native pool as #388 49#270, 50#276, 68#367, 70#377 

388 Fresh-frozen, same native pool as #387 49#267, 50#274, 68#368, 70#380 

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

390 Fresh-frozen, native, single-donor 71#383 

391 Fresh-frozen, native, multi-donor 65#356, 66#360 

Individualized Report ILR_RR72_FSV-BA.xlsx, Page 3 / 12 

D4
 

 Set 1 of 33 

Individualized RR LXXII Report: FSV-BA

α-Tocopherol, μg/mL Your [Analyte], μg/mL 

Median [Analyte], μg/mL 

270276367377387267274368380388357365375389383390356360391 

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%) 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. 

erum Comments History 

387 Lyophilized, same native pool as #388 49#270, 50#276, 68#367, 70#377 

388 Fresh-frozen, same native pool as #387 49#267, 50#274, 68#368, 70#380 

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

390 Fresh-frozen, native, single-donor 71#383 

391 Fresh-frozen, native, multi-donor 65#356, 66#360 

Individualized Report ILR_RR72_FSV-BA.xlsx, Page 4 / 12 

D5
 

 Set 1 of 33 

Individualized RR LXXII Report: FSV-BA

γ/β-Tocopherol, μg/mL Your [Analyte], μg/mL 

Median [Analyte], μg/mL 

270276367377387267274368380388357365375389383390356360391 

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%) 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. 

erum Comments History 

387 Lyophilized, same native pool as #388 49#270, 50#276, 68#367, 70#377 

388 Fresh-frozen, same native pool as #387 49#267, 50#274, 68#368, 70#380 

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

390 Fresh-frozen, native, single-donor 71#383 

391 Fresh-frozen, native, multi-donor 65#356, 66#360 

Individualized Report ILR_RR72_FSV-BA.xlsx, Page 5 / 12 

D6
 

 Set 1 of 33 

Individualized RR LXXII Report: FSV-BA

Total β-Carotene, μg/mL Your [Analyte], μg/mL 

Median [Analyte], μg/mL 

270276367377387267274368380388357365375389383390356360391 

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%) 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. 

erum Comments History 

387 Lyophilized, same native pool as #388 49#270, 50#276, 68#367, 70#377 

388 Fresh-frozen, same native pool as #387 49#267, 50#274, 68#368, 70#380 

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

390 Fresh-frozen, native, single-donor 71#383 

391 Fresh-frozen, native, multi-donor 65#356, 66#360 

Individualized Report ILR_RR72_FSV-BA.xlsx, Page 6 / 12 

D7
 

 Set 1 of 33 

Individualized RR LXXII Report: FSV-BA

Total α-Carotene, μg/mL Your [Analyte], μg/mL 

Median [Analyte], μg/mL 

270276367377387267274368380388357365375389383390356360391 

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%) 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. 

erum Comments History 

387 Lyophilized, same native pool as #388 49#270, 50#276, 68#367, 70#377 

388 Fresh-frozen, same native pool as #387 49#267, 50#274, 68#368, 70#380 

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

390 Fresh-frozen, native, single-donor 71#383 

391 Fresh-frozen, native, multi-donor 65#356, 66#360 

Individualized Report ILR_RR72_FSV-BA.xlsx, Page 7 / 12 

D8
 

 Set 1 of 33 

Individualized RR LXXII Report: FSV-BA

Total Lycopene, μg/mL Your [Analyte], μg/mL 

Median [Analyte], μg/mL 

270276367377387267274368380388357365375389383390356360391 

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%) 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. 

erum Comments History 

387 Lyophilized, same native pool as #388 49#270, 50#276, 68#367, 70#377 

388 Fresh-frozen, same native pool as #387 49#267, 50#274, 68#368, 70#380 

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

390 Fresh-frozen, native, single-donor 71#383 

391 Fresh-frozen, native, multi-donor 65#356, 66#360 

Individualized Report ILR_RR72_FSV-BA.xlsx, Page 8 / 12 

D9
 

 Set 1 of 33 

Individualized RR LXXII Report: FSV-BA

trans-Lycopene, μg/mL Your [Analyte], μg/mL 

Median [Analyte], μg/mL 

270276367377387267274368380388357365375389383390356360391 

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%) 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. 

erum Comments History 

387 Lyophilized, same native pool as #388 49#270, 50#276, 68#367, 70#377 

388 Fresh-frozen, same native pool as #387 49#267, 50#274, 68#368, 70#380 

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

390 Fresh-frozen, native, single-donor 71#383 

391 Fresh-frozen, native, multi-donor 65#356, 66#360 

Individualized Report ILR_RR72_FSV-BA.xlsx, Page 9 / 12 

D10
 

 Set 1 of 33 

Individualized RR LXXII Report: FSV-BA

Total β-Cryptoxanthin, μg/mL Your [Analyte], μg/mL 

Median [Analyte], μg/mL 

270276367377387267274368380388357365375389383390356360391 

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%) 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. 

erum Comments History 

387 Lyophilized, same native pool as #388 49#270, 50#276, 68#367, 70#377 

388 Fresh-frozen, same native pool as #387 49#267, 50#274, 68#368, 70#380 

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

390 Fresh-frozen, native, single-donor 71#383 

391 Fresh-frozen, native, multi-donor 65#356, 66#360 

Individualized Report ILR_RR72_FSV-BA.xlsx, Page 10 / 12 

D11
 

 Set 1 of 33 

Individualized RR LXXII Report: FSV-BA

Total Lutein&Zeaxanthin, μg/mL Your [Analyte], μg/mL 

Median [Analyte], μg/mL 

270276367377387267274368380388357365375389383390356360391 

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%) 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. 

erum Comments History 

387 Lyophilized, same native pool as #388 49#270, 50#276, 68#367, 70#377 

388 Fresh-frozen, same native pool as #387 49#267, 50#274, 68#368, 70#380 

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

390 Fresh-frozen, native, single-donor 71#383 

391 Fresh-frozen, native, multi-donor 65#356, 66#360 

Individualized Report ILR_RR72_FSV-BA.xlsx, Page 11 / 12 

D12
 Set 1 of 33 

Individualized Round Robin LXXII Report: FSV-BA 

Graphical Comparability Summary
 

Total Retinol α-Tocopherol Total β-Carotene T

D13

Retinyl palmitate γ/β-Tocopherol Total Lutein tr

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

Individualized Report 
 

 

Appendix E. Shipping Package Inserts for RR37 

The following five items were included in each package shipped to an RR37 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 25, 2012 

Dear Colleague: 

UNITED STATES DEPARTMENT OF COMMERCE 

National_ Institute of Standards and Technology 

Gaithersburg, Maryland 20899-

The samples within this package constitute Vitamin C Round Robin 37 (RR37) of the 2012 

Micronutrients Measurement Quality Assurance Program. RR3 7 consists of four vials of frozen 

serum test samples (#371, #372 #373, and #374), one vial each of two frozen control serum samples 

(CS #3 and CS #4), and one vial of ascorbic acid solid control material (Control). Please follow the 

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

control solutions gravimetrically, please prepare equivalent solutions 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.) 

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

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

target for CS #4 is (46.1±4.6;41.5 to 50.7) μmol/L. We expect your results for both of these 

controls to be within this ± 10% target range. If either of your result is significantly outside this 

range, your analysis system may not be suited to the analysis of MP A-preserved samples. In this 

case, please do not proceed to the analysis of the test samples but contact us at 301-975-3120 or 

jbthomas@nist.gov. 

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

may degrade your measurement system's performance (SA Margolis and E Park, "Stability of 

Ascorbic Acid in Solutions in Autosampler Vials", Clinical Chemistry 2001, 47(8), 1463-1464). 

You should suspect such degradation if you observe unusually large variation in replicate analyses. 

Please report your results (using the attached form) for RR37 by e-mail to david.duewer@nist.gov or 

fax to 301-977-0685 by September 28, 2012. If you have questions or comments regarding this 

study, please call me at (301) 975-3120 or e-mail me at jbthomas@nist.gov. 

ce Brown Thom 

am Coordinator/Research Chemist 

ytical Chemistry Division 

Chemical Science and Technology Laboratory 

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

RR37 Report Form for Ascorbic Acid Solid Control Material Preparation 

RR37 Report Form for Control Material and Test Sample Analyses 

E2

NISI 
 

 

 

 

 

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 ) + (gDiluent 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! 

Once you have confirmed that your system is properly calibrated, analyze the serum controls CS #3 

and CS #4 (see protocol below). The target range for CS #3 is (15.5 ±1.6; 13.9 to 17.1) μmol/L and 

the target range for CS #4 is (46.1 ±4.6; 41.5 to 50.7) μmol/L. 

If either of your measured values is not within its target range, 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 37 

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, 2012 

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 37 

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 # 3 Target: (15.5 ±1.6) μmol/L 

μmol/L of Sample CS # 4 Target: (46.1 ±4.6) μmol/L 

Serum Test Sample #371 μmol/L of Sample 

Serum Test Sample #372 μmol/L of Sample 

Serum Test Sample #373 μmol/L of Sample 

Serum Test Sample #374 μmol/L of Sample 

Were samples frozen upon receipt? Yes | No 

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

If “Other”, please describe: 

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

If “Other”, please describe: 

COMMENTS: 

Please return by September 28, 2012 

MMQAP Fax: 301-977-0685 

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

Gaithersburg, MD 20899-8392 

E6
 

 

SRM970 Lv1

Sam - 30's

SRM970 Lv2

Sam - 50's

Red

Orange

 

 

Participant #: ________ Date: _____________ 

Vitamin C Round Robin 37
 

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:
 

Label Form
 

VitC #371 Liquid frozen (1:1 serum:10% MPA) 

VitC #372 Liquid frozen (1:1 serum:10% MPA) 

VitC #373 Liquid frozen (1:1 serum:10% MPA) 

VitC #374 Liquid frozen (1:1 serum:10% MPA) 

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

CS #4 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 6392 Fax: 301-977-0685 

Gaithersburg, MD 20899-6392 Email: David.Duewer@NIST.gov 

E7
Appendix F. Final Report for RR37

The following five 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
December 7, 2012 

Dear Colleague: 

UNITED STATES DEPARTMENT OF COMMERCE 

National Institute of Standards and Technology 

Gaithersburg, Maryland 20899-

Enclosed is the summary report of the results for Round Robin 37 (RR37) forthe 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 "adjusted 

median absolute deviation from the median" (MADe) is used to estimate the expected standard deviation, 

and we estimate the coefficient of variation (CV) as IOOxMADe/median. 

RR37 consisted of four test samples (#371, #372,, #373, and #374), one vial each of two frozen control 

serum control samples (CS #3 and CS #4 ), and one vial of solid control material (Control) 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 performance, we suggest that you obtain and analyze a 

unit of Standard Reference Material (SRM) 970 Vitamin C in Frozen Human Serum. SRM 970 can be 

purchased from the NIST SRM Program at www.nist.gov/srm; phone: 301-975-6776; fax: 301-948-3730. 

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

consultation. 

Samples for the first vitamin C round robin (RR38) of the 2013 MMQAP will be shipped starting 

January 22, 2013. Please contact us immediately if this schedule is problematic for your laboratory. 

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

david.duewer@nist.gov or me atjbthomas@nist.gov, 301-975-3120, or fax: 301-977-0685. 

Sincerely, 

~IllUlnTI ~ t_;/b f/J 

· e Brown Thomas, M.B.A . 

Research Chemist 

Analytical Chemistry Division 

Material Measurement Laboratory 

Enclosures 

cc: L. C. Sander 

David L. Duewer, Ph.D. 

Research Chemometrician 

Analytical Chemistry Division 

Material Measurement Laboratory 

F2

NISI 
 

 

 

 

 

 

 

 

 

The NIST MMQAP Vitamin C Round Robin 37 (RR37) report consists of: 

Page “Individualized” Report 

1 Summary of 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 RR37 sample measurements. 

Page “All-Lab” Report 

1 A tabulation of results and summary statistics for total ascorbic acid [TAA] in the RR37 

samples and control/calibration solutions. 

Serum-Based Samples. Two serum controls and four test samples were distributed in RR37. 

CS#3	 a (13.9 to 17.1) μmol/L material ampouled in late 2009 

CS#4	 a (41.5 to 50.7) μmol/L material ampouled in late 2009 

S37:1	 SRM 970 level 1, ampouled in mid-1998, previously distributed as an “Unknown” in RRs 11 

to 16, 19, 20 23, 25, 29, 31, and 34 

S37:2	 Ampouled in late 2001, previously distributed in RRs 17, 18, 20, 22, 23, 27, and 31 

S37:3	 SRM 970 level 2, ampouled in mid-1998, previously distributed as an “Unknown” in RRs 11 

to 15, 18, 20 22, 25, 29, and 36 

S37:4	 Ampouled in late 2001, previously distributed in RRs 16, 17, 20, 21, 23, 27, and 30 

Results. 

1)	 All participants who prepared the four 5% metaphosphoric acid (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 solution (≈1.03 gm/mL), the observed wavelength maximum 

of “Dilute Solution #1” (≈244 nm), the observed absorbance at that maximum (≈0.58), and the 

calculated E1%#1” (≈560 dL/g·cm). 

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

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

are linear (R2

 close to 1 and the root-mean-square (RMS) residual close to 0.0) and well calibrated 

(intercepts close to 0 and slopes close to 1). 

3)	 The Measured = p+q*Median regression parameters for samples S37:1 to S37:4 (columns 23 to 26 of 

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

0.0). However, the intercepts and slopes continue to indicate that there are systematic differences in 

the response of the various measurement procedures to the TAA in the 5% aqueous metaphosphoric 

acid (MPA) of the test samples. 

4)	 The variability of the measured values after calibration to the control solutions (the final 6 columns of 

the All-Lab Report) continues to be as great or greater than that of the measured values themselves. 

The primary source of the systematic differences in response of the measurement procedures appears 

to be the presence of serum components in the sample matrix, not the MPA preservative. On this 

basis, we intend to drop the standard solution arm of the MMQAP Vitamin C Round Robin studies 

beginning with RR38. 

F3
Appendix G. “All-Lab Report” for RR37 

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" 37 - Fall 2012 

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#3 CS#4 S37:1 S37:2 S37:3 S37:4 Inter Slope R2 R

VC-MA 25/09/12 57.8 28.3 14.8 60.0 29.9 15.0 0.0 -0.03 1.04 1.000 0.4 1.036 243. 0.5510 541.6 16.5 49.2 8.0 20.5 27.8 44.0 -0.48 1.00 0.999 

VC-MB 06/08/12 60.7 30.3 14.9 60.1 31.2 14.5 0.0 0.11 0.99 0.999 0.8 1.030 243.5 0.5990 560.3 12.6 46.5 8.8 21.7 26.8 44.7 0.20 0.99 0.999 

VC-MC 20/08/12 60.6 30.6 15.2 61.7 31.3 15.8 0.0 0.15 1.02 1.000 0.2 1.024 244. 0.5952 558.0 16.0 48.4 8.6 22.6 28.2 48.9 -1.36 1.11 0.997 

VC-MG 15/08/12 61.2 31.8 16.8 63.7 32.1 16.8 0.0 -0.43 1.04 1.000 0.6 1.026 243.6 0.6140 569.4 15.1 47.5 8.2 22.2 28.1 48.2 -1.50 1.10 0.998 

VC-MH 12/09/12 60.1 30.2 14.9 59.7 29.4 14.7 0.0 -0.19 0.99 1.000 0.4 1.031 243.3 0.5933 560.8 14.6 45.7 7.4 19.7 25.4 44.7 -2.13 1.03 0.996 

VC-MI 27/09/12 55.3 27.7 13.8 53.9 23.4 13.5 0.0 -0.69 0.97 0.994 2.2 1.031 15.2 43.6 9.1 20.2 27.8 44.9 -0.07 1.00 0.997 

VC-MJ 29/08/12 55.1 28.1 15.1 55.5 26.8 13.4 0.7 -0.61 1.00 0.997 1.5 1.015 255a 0.340a 349.9a 22.2 53.0 10.9 25.9 31.7 50.1 2.09 1.08 0.999 

VC-MN 12/09/12 57.8 29.2 13.9 59.7 30.2 13.5 0.0 -0.35 1.04 1.000 0.5 1.032 243.9 0.5694 559.7 15.1 43.2 8.5 21.5 26.6 43.3 0.44 0.96 0.999 

VC-NM 10/08/12 56.1 29.4 13.8 58.2 30.2 14.3 0.0 -0.07 1.04 1.000 0.2 1.028 242. 0.5450 551.4 13.5 41.8 7.3 17.7 24.8 41.8 -1.75 0.96 0.996 

9 9 9 9 9 9 9 9 7 7 7 9 9 9 9 9 9 

58.3 29.5 14.8 59.2 29.4 14.6 0.1 1.028 243.3 0.5810 557.3 15.7 46.5 8.5 21.3 27.5 45.6 

2.4 1.3 0.9 3.0 2.7 1.2 0.2 0.006 0.7 0.0261 8.7 2.7 3.5 1.1 2.3 2.0 2.8 

55.1 27.67 13.8 53.9 23.40 13.4 0.0 1.015 242.0 0.5450 541.6 12.6 41.8 7.3 17.7 24.8 41.8 

56.1 28.33 13.9 58.2 29.35 13.5 0.0 1.026 243.2 0.5602 554.7 14.6 43.6 8.0 20.2 26.6 44.0 

57.8 29.39 14.9 59.7 30.18 14.5 0.0 1.030 243.5 0.5933 559.7 15.1 46.5 8.5 21.5 27.8 44.7 

60.6 30.31 15.1 60.1 31.23 15.0 0.0 1.031 243.8 0.5971 560.5 16.0 48.4 8.8 22.2 28.1 48.2 

61.2 31.83 16.8 63.7 32.15 16.8 0.7 1.036 244.0 0.6140 569.4 22.2 53.0 10.9 25.9 31.7 50.1 

3.7 1.6 0.4 2.2 1.6 1.4 0.0 0.0 0.6 0.0307 2.6 1.3 4.1 0.7 1.7 1.5 2.0 

6 5 3 4 5 10 0.33 0.26 5.2 0.5 9 9 8 8 5 5 

MADe eSD 

CV CV 

Median Median 

%75 %75 

Max Max 

Min Min 

%25 %25 

N N 

Average Average 

SD SD 

Grav, μmol/L Measured, μmol/L Measured = a + b*Grav Spectrophotometry Measured, μmol/L Measured = p+q*Med

a ) 5% Trichloroacetic acid solution 

RRvc37_ALR.xls 
Appendix H. Representative “Individualized Report” for RR37 

Each participant in RR37 received an “Individualized Report” reflecting their reported 

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

“VC-MA”. 

H1
 Set 1 of 9 

Vitamin C "Round Robin" 37 Report: Participant VC-MA
 

MPA Dilute Solution 1 Control/Calibration Solutions 

Density Spectrophotometry Ymeas = Inter + Slope* Xgrav 

Date RR Method 

02/24/10 32 HPLC-EC 

09/27/10 33 HPLC-EC 

02/28/11 34 HPLC-EC 

08/24/11 35 HPLC-EC 

02/02/12 36 HPLC-EC 

09/25/12 37 HPLC-EC 

g/mL 

1.035 

1.037 

1.039 

1.039 

1.035 

1.035 

λmax Amax E1% 

242.0 0.566 545.1 

244.0 0.560 540.5 

244.0 0.575 555.2 

242.0 0.568 547.7 

244.0 0.561 550.5 

243.0 0.551 541.6 

Inter Slope R2 SEE 

0.3 1.03 1.000 0.46 

0.4 1.08 1.000 0.43 

0.6 1.14 1.000 0.78 

0.0 1.03 1.000 0.24 

-0.4 1.05 1.000 0.55 

0.0 1.04 1.000 0.41 

Mean 1.037 243.2 0.56 546.8 Pooled SEE 0.50 

SD 0.002 1.0 0.01 5.6 

[TAA] mmol/Lsample 

12 26.7 0.5 1.8 

8 23.0 0.5 1.4 

48.3 1.3 2.2 

Date RR Sample Rep1 Rep2 Fadj Mean SDdup 

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 

8.5 8.3 1.0 8.4 0.1 

8.0 8.1 1.0 8.0 0.0 

N Mean SDrepeat SDreprod 

09/23/98 11 S11:1 14 8.2 0.3 0.5 

04/02/99 12 S12:1 

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 

02/28/11 34 S34:1 

09/25/12 37 S37:1 

09/23/98 11 S11:2 

04/02/99 12 S12:2 

09/17/01 13 S13:2 

09/27/01 14 S14:4 

09/18/01 15 S15:2 

03/20/03 18 S18:3 

02/23/04 20 S20:4 

03/08/05 22 S22:4 

08/28/06 25 S25:2 

08/11/08 29 S29:3 

02/02/12 36 S36:3 

09/25/12 37 S37:3 

12/12/02 17 S17:2 

03/20/03 18 S18:1 

02/23/04 20 S20:1 

03/08/05 22 S22:2 

10/17/05 23 S23:2 

10/05/07 27 S27:1 

09/10/09 31 S31:1 

09/25/12 37 S37:2 

11/18/02 16 S16:3 

12/12/02 17 

02/23/04 20 

09/13/04 21 

10/17/05 23 

10/05/07 27 

03/03/09 30 

09/25/12 37 

50.7 47.7 0.5 24.6 1.1 

49.5 45.9 0.5 23.9 1.3 

27.6 27.7 1.0 27.7 0.1 

25.7 26.4 1.0 26.0 0.5 

25.4 25.6 1.0 25.5 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 

25.6 25.7 1.0 25.6 0.1 

28.3 28.5 1.0 28.4 0.1 

27.9 27.8 1.0 27.8 0.1 

23.3 23.4 1.0 23.4 0.1 

22.7 23.7 1.0 23.2 0.7 

25.1 24.1 1.0 24.6 0.7 

22.7 22.7 1.0 22.7 0.0 

25.5 24.4 1.0 24.9 0.8 

22.9 22.4 1.0 22.6 0.4 

21.5 22.6 1.0 22.1 0.7 

20.4 20.7 1.0 20.5 0.2 

49.9 44.9 1.0 47.4 3.5 

49.7 49.1 1.0 49.4 0.4 

50.6 50.0 1.0 50.3 0.4 

47.1 47.0 1.0 47.0 0.0 

49.8 48.8 1.0 49.3 0.7 

48.6 47.6 1.0 48.1 0.8 

51.2 50.4 1.0 50.8 0.6 

43.9 44.1 1.0 44.0 0.1 

8 

S17:3 

S20:2 

S21:4 

S23:3 

S27:2 

S30:2 

S37:4 

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

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

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

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Individualized Report [ILR_RR37_VC-MA.XLS]Summary Page 1/2 
 

 

NIST, RR 22

Vitamin C "Round Robin" 37 Report: Participant VC-MA 

 Set 1 of 9 

Total Ascorbic Acid, μmol/mL 

[Total Ascorbic Acid], μmol/L

RR11RR12RR13RR14RR15RR16RR18RR19RR20RR22RR23RR25RR29RR31RR34RR36RR37

S17:2S18:1S20:1S22:2S23:2S27:1S31:1S37:2S16:3S17:3S20:2S21:4S23:3S27:2S30:2S37:4 

Your [Total Ascorbic Acid], μmol/L 

Median [Total Ascorbic Acid], μmol/L 

Apparent Precision, SD 

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 

S37:1 SRM970 Lv I - distributed in RRs 11, 12, 13, 14, 15, 16, 19, 20, 23, 25, 29, 31, and 34 

S37:2 Distributed in RRs 17, 18, 20, 22, 23, 27, and 31 

S37:3 SRM970 Lv II - distributed in RRs 11, 12, 13, 14, 15, 18, 20, 22, 25, 29, and 36 

S37:4 Distributed in RRs 16, 17, 20, 21, 23, 27, and 30 

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Individualized Report [ILR_RR37_VC-MA.XLS]Pics Page 1/2