AOAC SPIFAN Nutrients ERP (December 7, 2022)

Amino-07 (SLV) 10-2022 FOR ERP USE ONLY DO NOT DISTRIBUTE

concentration of a substance that can be reported with confidence to be distinguishable from blank results. The LoD determined as the method detection limit must be based on the analysis of samples that have been taken through the whole measurement procedure using results calculated with the same equation as for the test samples. It is this method detection limit that is most useful estimate of LoD for method validation [7]. The LoD was estimated from replicate analyses ( n = 10) of an adult nutritional formula with a low concentration of taurine (Table 7; Eqns 13–16; Appendix E).

Table 7: Limits of detection and quantitation

Value (mg hg − 1 )

Parameter

0 0 ′

0.0451 0.0143

limit of detection

0.04 0.14

limit of quantitation a

K Q = 10

a

The LoD was calculated as 0.04 mg hg − 1 RTF and the LoQ is 0.14 mg hg − 1 RTF which complies with SMPR 2014.013 limit of 0.5 mg hg − 1 RTF.

Accuracy

Bias against certified reference material Bias is a measurement of systematic error between a measured value and the true value. However, as the true value is never known, an accepted reference value is used. A certified reference material contains assigned values accompanied by an uncertainty and stated level of confidence. Two certified reference materials were evaluated (NIST 1849a, NIST 1869) although neither has a certified value, however, a reference value is given for both (Table 8; Eqns 17–20; Appendix F). Bias against a certified reference material is not a method performance requirement given in SMPR 2014.013. Differences between the measured value and certified value are determined with the mean and standard deviation of the differences, and the test-statistic calculated. The null hypothesis is that there is no difference between the measured results and the reference value. At the α = 0.05 level of confidence, the probability of the observation under the null hypothesis is assessed [4].