Page 121 - Analytical method for food addtives

E210–13: Benzoic acid 71

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Table 7.4 Performance characteristics for benzoic acid in orange juice (Journal of
AOAC International (1995) 78 80)
Sample (spike level) 0.5 1 3 4 10

No. of laboratories 9 9 9 9 9
Units µg/mL µg/mL µg/mL µg/mL µg/mL
Mean 0.57 1.01 3.01 3.78 9.61
Mean recovery % 114.0 101.0 100.3 94.5 96.1
S 0.113 0.084 0.159 0.184 0.461
r
RSD 19.91 % 8.27 % 5.28 % 4.87 % 4.79 %
r
r 0.316 0.235 0.445 0.515 0.714
S 0.159 0.161 0.276 0.255 0.665
R
RSD 27.90 % 15.97 % 9.16 % 6.74 % 6.92 %
R
Ho 1.60 1.00 0.68 0.52 0.61
R
R 0.445 0.451 0.773 0.714 1.862
Key
Mean The observed mean. The mean obtained from the collaborative trial data.
r Repeatability (within laboratory variation). The value below which the absolute difference
between two single test results obtained with the same method on identical test material under the
same conditions may be expected to lie with 95 % probability.
S r The standard deviation of the repeatability.
RSD The relative standard deviation of the repeatability (S × 100/mean).
r
r
R Reproducibility (between-lab variation). The value below which the absolute difference between
two single test results obtained with the same method on the identical test material under different
conditions may be expected to lie with 95 % probability.
S R The standard deviation of the reproducibility.
RSD The relative standard deviation of the reproducibility (S × 100/mean).
R
R
Ho The HORRAT value for the reproducibility is the observed RSD value divided by the RSD
R R R
value calculated from the Horwitz equation.