AOAC SPIFAN Nutrients ERP (December 7, 2022)

Amino-06 (SLV) 10-2022 FOR ERP USE ONLY DO NOT DISTRIBUTE

B. Samples

During this SLV AOAC SPIFAN samples supplied by National Institute of Standards and Technology (NIST) and in-house samples were used. The reference materials NIST SRM 1869 and 1849a were used to assess the accuracy of the method based on their reference value. All samples except NIST SRM 1849a were used to assess the precision of themethod. Samples NIST RM8261, 10175 and 1869 were used for spike recovery experiments based on their matrix. Details of all the used samples can be found in table 7.

Table 7. SLV Samples

Description

Sample No Sample code

NIST RM 8260 NIST RM 8261

1 2 3 4 5 6 8 9

Infant formula, powder, hydrolyzed milk protein based

Adult nutritional, powder, high protein

NIST RGTM 10175 Infant formula, powder, partially hydrolyzed soy protein based

NIST SRM 1869

Infant/adult formula, powder, milk/whey/soy based

NIST SRM 1849b Infant/adult formula, powder, milk based NIST SRM 1849a Infant/adult formula, powder, milk based SPIFAN DOMY545 Adult nutritional, RTF, high protein

Liquid IFT

Infant formula, RTF, milk based

C. Calibration fit

The linearity of the calibration fit was assessed on three different days. A seven level calibration line was used for the experiments. Linear weighted regression lines were determined by the use of Minitab 2.0 (Minitab Ltd., Coventry, UK). Calibration model and correlation coefficient were in good agreement with used LC-MS software. The summarized results are presented in table 8. The calculated relative residuals were smaller than 7% regarding the working range of the calibration line. The experimental data and residuals plot can be found in appendix A.

Table 8. Linearity and calibration line of taurine

Amount in RTF (mg/100 g)

Concentration (mg/L)

Correlation coefficient (%)

Residuals (%)

Date

Calibration model

0,3-110 0,3-110 0,3-110

31-8-2022 0,03-11

y=0,002104x-0,00183 y=0,002451x+0,0069 y=0,002393x+0,0243

100,00

<5 <7 <5

7-9-2022

0,03-11

99,93 99,98

13-9-2022 0,03-11

D. LOD and LOQ

The limit of detection (LOD) and limit of quantitation (LOQ) of the method is determined according the AOAC SLV guidelines 4 . A method blank was spiked with a low concentration of taurine near the expected LOQ. Next to the spiked method blank a method blank was included to calculate the mean blank. A total of 24 measurements of spiked method blanks were performed over six days. The standard deviation of these analyses were calculated. The standard deviation was multiplied by three for the LOD (S LOD ) and multiplied by ten for the LOQ (S LOQ ). The LOD and LOQ were then determined by adding the S LOD and S LOQ to the blank mean. The determined LOD of the method is 0,15 mg/100g and the LOQ is 0,29 mg/100g. The