AOAC SPIFAN Nutrients ERP (December 7, 2022)

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

The calculated p -values for both NIST 1949a and NIST 1869 indicate that no bias between the reference values and the measured values by the candidate method could be found.

Table 8: Results for bias experiment against NIST certified reference materials Parameter NIST 1849a NIST 1869 reference value 36.6 mg hg − 1 37.2 mg hg − 1 uncertainty 1.8 mg hg − 1 3.2 mg hg − 1 coverage factor ( ) 2 2 degrees of freedom ( CRV ) a 60 60 mean ( ) 36.7 mg hg − 1 35.4 mg hg − 1 standard deviation ( ) 1.47 mg hg − 1 2.59 mg hg − 1 number of replicates ( ) 24 24 95 % confidence interval 36.0–37.3 mg hg − 1 34.3–36.5 mg hg − 1 t stat 0.067 1.025 degrees of freedom ( ) 72.36 72.24 p -value 0.95 0.31 a Calculated for k , using a 2-sided t -distribution at α = 0.05. An empirical model for doing this calculation was obtained by fitting 1/DF vs log t 0.05 to a 4th order polynomial for integral values of DF from 2–100 DF. The maximum relative error over the fitted range was 0.06 %. Bias against reference method The candidate HILIC-MS/MS was evaluated for bias against AOAC 997.05, an HPLC-UV method for taurine [8], by testing a set of different products and comparing the results by using a paired t -test (Table 9; Eqns 21–24; Appendix G). Bias against a reference method is not a method performance requirement given in SMPR 2014.013.

Table 9: Results for bias experiment against AOAC 997.05

Reference Method 37.0mg hg − 1 2.66 mg hg − 1

HILIC-MS/MS Method 37.6 mg hg − 1 3.11 mg hg − 1

Parameter mean ( ) standard deviation ( ) number of replicates ( ) mean difference ( ) standard deviation difference ( ) t stat degrees of freedom ( = − 2 ) p -value

16

− 0.9 mg hg − 1

1.8 mg hg − 1

− 1.36

14

0.10