AOAC SPIFAN Nutrients ERP (December 7, 2022)

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

Linearity was evaluated by testing nine calibration standards through the analytical procedure on three different days (Table 3; Eqns 1–5; Appendix C). The concentration range selected was spanned an order of magnitude lower and higher than that of calibration range defined in the method. Regression and residual plots of the ratios of the peak areas of analyte taurine with internal standard against the ratios of the concentrations of analyte taurine with internal standard were prepared.

Table 3: Linearity—Taurine standard concentrations

Sample RTF (mg hg − 1 ) b

13 C 2 15 N Taurine ( μ g mL − 1 )

Taurine ( μ g mL − 1 )

Ratio a

Ranges

0.06

6 6 6 6 6 6 6 6 6

0.01 0.05

0.27 1.35

0.3 0.6

0.1 0.5

2.7

Range of concentration of calibration in linearity study

3 6

13.5

Range of concentration

Range of concentration of calibration in method

1 5

27

of typical samples

30 60

135 270

10 50

300 600

1350

100 2700 a Concentration ratio taurine/ 13 C 2 15 N taurine in linearity standards b Equivalent ready-to-feed sample concentration of taurine in linearity standard

Linearity of calibration was demonstrated by the calculation of correlation coefficients and visual evaluation of regression and residuals plots (Figures 1–4).

Figure 1: Regression plots of standards on three different days