Page 120 - Analytical method for food addtives

70 Analytical methods for food additives

Table 7.3 Performance characteristics for benzoic acid in almond paste, fish
1
homogenate and apple juice (JAOAC (1983) 66, 775, NMLK collaborative study)
Samples Almond paste Fish homogenate Apple juice

No. of laboratories 8 8 8 8 6 8
Units mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg
Mean value 982 1987 501 2044 41 1001
S 36 62 14 40 2.6 9.4
r
RSD 3.7 % 3.2 % 2.8 % 2.0 % 6.1 % 2.7 %
r
S 33 83 27 76 5.8 32
R
RSD 4.7 % 5.3 % 6.1 % 4.3 % 14.7 % 3.5 %
R
Ho 0.83 1.04 0.97 0.85 1.62 0.61
R
Av recovery 100.4 % 98.8 % 100.1 % 98.3 % 105.9 % 94.4 %
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.