Page 122 - Analytical method for food addtives

72 Analytical methods for food additives

Table 7.5 Performance characteristics for benzoic acid in orange squash, cola drinks,
beetroot and pie filling 11
Sample Orange squash Cola drink

No. of laboratories 8 7 7
Units mg/kg mg/kg mg/kg
Mean 455.4 471.4 752.9 1234.4
Mean recovery % 100 99 95 89
S 7.06 7.63 6.71
r
RSD 2% 1 % 1%
r
r 20 21 19
S 18.79 30.73 89.48
R
RSD 4% 4 % 7%
R
R 53 86 251
Ho 0.6 0.7 1.3
R
Sample Beetroot Pie filling
No. of laboratories 9 9
Units mg/kg mg/kg
Mean 1977.6 1752.0 1565.3 1773.2
Mean recovery % 94 93 95 97
S 118.47 42.80
r
RSD r 6 % 3 %
r 331 120
S 225.25 196.5
R
RSD R 12 % 12 %
R 631 550
Ho 2.3 2.3
R
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
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.