Page 190 - Analytical method for food addtives

E249–50: Nitrites 127

Table 9.4 Performance characteristics for nitrite in foods 16
Sample Sausage Baby food Sausage
No. of laboratories 11 11 11 11
Units mg/kg mg/kg mg/kg mg/kg
Mean 47 160 58 161
S 6.1 6.1
r
S 4.1 9.3 5.0 12.5
R
RSD 8.7 % 5.8 % 8.6 % 7.8 %
R
Horrat value 1.0 0.8 1.0 1.0
Sample Salami Pâté Salami
No. of laboratories 11 14 13 11
Units mg/kg mg/kg mg/kg mg/kg
Mean 7 65 52 9
S 2.2 2.2
r
S 2.0 11.0 4.7 1.5
R
RSD 27.7 % 17.1 % 8.9 % 17.0 %
R
Horrat value 2.3 2.0 1.0 1.5
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.
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 R The relative standard deviation of the reproducibility (S × 100/mean)
R
Horrat The observed RSR value divided by the RSD value calculated from the Horwitz equation at
R
R
value the concentration of interest (RSD = 2 1–0.5logC )
R