Page 150 - Analytical method for food addtives

E220–8: Sulphites 95

Table 8.6 Performance characteristics for total sulphite in starch, lemon juice, wine
cooler, dehydrated seafood and instant mashed potatoes 10,11
Interlaboratory test carried out by US Army Natick research 11
Sample Starch Diluted lemon juice

Spike 0 10 30 0 10 30
No. of laboratories 16 16 16 12 16 14
Units µg/g µg/g µg/g µg/g µg/g µg/g
Mean value a 0 7.7 27.3 21.2 11.2 30.3
S 0 0.7 2.4 2.1 1.9 5.2
r
RSD r 0 9.5 % 8.8 % 9.8 % 17.0 % 17.2 %
S R 0 1.3 3.9 2.1 2.7 5.2
RSD 0 16.3 % 14.1 % 9.8 % 24.1 % 17.2 %
R
Sample Wine cooler Dehydrated seafood
Spike 0 10 30 0 40 80
No. of laboratories 16 18 16 18 18 18
Units µg/g µg/g µg/g µg/g µg/g µg/g
Mean value a 21.8 11.8 32.9 35.4 28.8 63.2
S r 1.0 2.4 1.8 4.7 5.3 3.8
RSD 4.4 % 20.4 % 5.4 % 13.2 % 18.5 % 6.0 %
r
S R 3.7 4.6 4.3 9.1 11.2 18.9
RSD 17.1 % 39.3 % 13.0 % 25.8 % 38.9 % 29.9 %
R
Sample Instant mashed potato
Spike 0 80 400
No of laboratories 18 14 18
Units µg/g µg/g µg/g
Mean value a 384 92.8 422
S r 19.5 10.2 109.8
RSD r 5.1 % 11.0 % 26.0 %
S 32.5 16.3 109.8
R
RSD 8.5 % 17.5 % 26.0 %
R
a Mean initial sulphite level of unspiked samples. Mean recovery of added sulphite for spiked samples
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