AOAC SPIFAN Stakeholder Panel Meeting Book (March 12, 2020)

LOD/LOQ: results (µg/g) for sample blank run as a sample Note: linearity and LOQ proved the need to use low-ppt blank nitric acid vs. low-ppb. Method should clarify!

Conclusion: with high purity acid, LOQs met SMPR criterion

Na

Mg

P

K

Ca

Mn

Fe

Cu

Zn

Cr

Se

Mo

DAY 1

-0.002142 -0.000191 -0.001660 -0.000586 -0.001709 0.000008 0.000302 0.000008 0.004890 -0.000000691 -0.000009228 0.000003360

DAY 2

-0.000162 0.001556 -0.000133 0.006475 0.001214 -0.000027 -0.000012 0.000024 0.000369 -0.000017715 -0.000008157 0.000007865

DAY 3

-0.000661 0.000759 -0.001299 0.006220 0.012982 0.000031 0.000309 0.000052 -0.001187 0.000002580 0.000004832 0.000003079

DAY 4

-0.002044 0.000257 -0.000492 -0.002640 0.008721 0.000036 0.000621 0.000044 -0.000753 0.000003739 0.000016000 0.000001000

DAY 5

-0.000794 0.000690 0.001867 0.005627 0.008484 0.000030 0.000431 0.000059 0.000207 0.000015421 0.000011292 0.000010979

MEAN -0.00116060 0.00061420 -0.00034340 0.00301920 0.00593840 0.00001560 0.00033020 0.00003740 0.00070520 0.00000067 0.00000295 0.00000526

SD 0.0008838 0.0006499 0.0013783 0.0043015 0.0060133 0.0000261 0.0002308 0.0000210 0.0024280 0.0000119 0.0000113 0.0000041

LOQ mg/100g

0.038

0.036

0.067

0.23

0.33

0.0014

0.013

0.0012

0.12

0.00060

0.00058

0.00023

SMPR mg/100g

10

3.0

15

10

20

0.001

0.010

0.001

0.10

0.002

0.001

0.002

Six-Day Precision Data - Procedure

On each of six independent days with two different analysts, duplicate samples were prepared and analysed for the concentration of the 12 elements in all matrices including SRM. Averaged the results of the duplicates and reported one daily mean for each of the 10 samples. From the 6-daily means, reported the overall mean and % RSD (the intermediate precision). Two malt-based sample matrices, i.e., Boost and Horlicks powders, required double digestion and higher sample weight (~ 3 g direct weight) due to low iron recoveries. The sample preparation procedure for these matrices is different from the other matrices and is a deviation from the normal reconstitution procedure. The method may require amendment w.r.t. to the sample preparation procedure for these two matrices. Ten data points were collected for the SRM 1849a to complete this SLV study.