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200 Analytical methods for food additives

Table 18.3 Performance characteristics for total phosphorus in collaborative trial
samples 2
Sample Potato flour Sausage Cold ham

Analyte Total phosphorus Total phosphorus Total phosphorus
No. of laboratories 10 12 11
Units g/100 g g/100 g g/100 g
Mean value 0.0761 0.166 0.233
S 0.0016 0.0079 0.0091
r
RSD 2.0 % 4.8 % 3.9 %
r
r 0.0044 0.022 0.026
S 0.0035 0.0115 0.018
R
RSD 4.7 % 6.9 % 7.7 %
R
R 0.0099 0.032 0.050
Ho 0.79 1.3 1.6
R
Sample Infant formula Cheese Skimmed milk
Analyte Total phosphorus Total phosphorus Total phosphorus
No. of laboratories 11 10 12
Units g/100 g g/100 g g/100 g
Mean value 0.285 0.641 0.960
S 0.015 0.0096 0.010
r
RSD 5.4 % 1.5 % 1.1 %
r
r 0.043 0.027 0.029
S 0.017 0.027 0.034
R
RSD 6.1 % 4.1 % 3.6 %
R
R 0.049 0.074 0.095
Ho 1.3 0.97 0.88
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 r The standard deviation of the repeatability.
RSD r The relative standard deviation of the repeatability (S × 100/mean).
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 R The relative standard deviation of the reproducibility (S × 100/mean).
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.