Page 147 - Analytical method for food addtives

92 Analytical methods for food additives

Table 8.3 Performance characteristics for sulphites in hominy, fruit juice and seafood 2
Identified in interlaboratory test conducted for FDA 4
Sample Hominy Fruit juice Seafood
Analyte Sulphite Sulphite Sulphite
No. of laboratories 18 21 20
Units mg/kg mg/L mg/kg
Mean value 9.17 8.05 10.41
S r 1.33 1.36 1.47
RSD 14.49 % 16.9 % 14.13 %
r
r 3.72 3.81 4.12
S R 1.42 1.62 2.77
RSD 15.5 % 20.14 % 26.62 %
R
R 3.98 4.54 7.76
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 The standard deviation of the repeatability.
r
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 The standard deviation of the reproducibility.
R
RSD The relative standard deviation of the reproducibility (S × 100/mean).
R R

Table 8.4 Performance characteristics for sulphites in wine, dried apples, lemon juice,
potato flakes, sultanas and beer 6
Interlaboratory test conducted by the Max von Pettenkofer Institute of the Federal Health
Office, Food Chemistry Department, Berlin, BRD
Sample Sultanas Beer

Analyte Sulphite Sulphite
No. of laboratories 13 14
Units mg/kg mg/L
Mean value 260 4.9
S 16 0.3
r
RSD r 6 % 5.8 %
r 45 0.8
S 46 0.6
R
RSD R 18 % 11.6 %
R 129 1.6