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. Author manuscript; available in PMC: 2017 Apr 27.
Published in final edited form as: J Agric Food Chem. 2016 Apr 15;64(16):3167–3175. doi: 10.1021/acs.jafc.5b05016

Table 2a.

Vitamin D3 and 25(OH)D3 in Food Samples Analyzed by Five Participating Laboratoriesa,b
mean vitamin D3 (μg/100 g)
mean 25(OH) D3 (μg/100 g)
chicken liver dried bovine liver (NIST 1577c) whole egg powder (NIST 1845a) ground beef meat homogenate (NIST 1546a) dietary supplement (fill only) chicken liver dried bovine liver (NIST 1577c) whole egg powder (NIST 1845a) ground beef meat homogenate (NIST 1546a) dietary supplement (fill only)
Trial 1
Laboratory A 1.35 <0.05c 4.42 0.28 0.24 61 200 0.48 1.42 1.29 0.28 0.09 2.79
Laboratory B 1.63 0.016 5.10 0.27 0.257 59 357 0.57 1.62 1.37 0.33 0.12 1.75
Laboratory C 1.65 0.05 5.03 0.31 0.23 51 256 0.50 1.81 1.12 0.29 0.09 1.78d
Laboratory D 1.46 0.06 4.20 0.31 e 0.46 1.39 1.66 0.27 0.11
Trial 2
Laboratory A 1.22 <0.05c 4.23 0.25 0.17 60 200 0.52 1.46 1.15 0.29 0.08 2.24
Laboratory B 1.48 0.014 4.09 0.28 0.23 64 280 0.50 1.26 1.04 0.25 0.09 0.58
Laboratory C 1.72 0.05 4.71 0.28 0.24 46 653 0.45 1.83 1.14 0.46 0.08 1.66e
Laboratory D 1.42 0.05 3.90 0.29 0.25 0.52 1.39 1.46 0.31 0.13
Laboratory E 1.29 0.07 0.30 0.26 0.46 1.34 0.33 0.08
combined
mean 1.47 0.043 4.49 0.284 0.233 56 390 0.495 1.51 1.25 0.315 0.093 1.82
SD 0.20 0.025 0.45 0.023 0.034 7160 0.041 0.21 0.20 0.074 0.019 0.82
reproducibility% RSD 13.3 58.0 10.0 8.0 14.8 12.7 8.3 14.1 16.0 23.5 20.7 45.1
Horwitz ratio 0.4 1.1 0.4 0.2 0.4 2.1 0.2 0.5 0.5 0.6 0.5 1.6
repeatability % RSD 6.9 38.7 2.8 6.2 9.7 2.9 3.4 3.6 5.4 15.6 10.6 14.8
a

Shaded cells indicate no data reported.

b

Values for foods in this table are means from triplicate analyses within each trial reported by Laboratories A, B, C and E and duplicate analyses from Laboratory D.

c

Laboratory A reported a vitamin D3 level of <0.05 for dried bovine liver (NIST 1577c) in Trial 1 and Trial 2, which is lower than the laboratory’s limit of quantification. Therefore, these values were omitted from mean and SD calculations.

d

Laboratory C conducted both of its trials on the same day, not two months apart as the other laboratories did.

e

Laboratory D indicated uncertainty about the quality of its data on meat homogenate (NIST 1546a). Therefore, this value was considered an outlier and excluded from the results reported here.

Abbreviations: NIST, National Institute of Standards and Technology (Gaithersburg, MD); SD, standard deviation; RSD, relative standard deviation