AOACSPDSMethods-2017Awardsv2

61

1456 K oshy et al .: J ournal of AOAC I nternational V ol . 99, N o . 6, 2016

Table 9. Precision of peak areas and retention times for sample WS/06Lot10

Peak area

Retention time

Weight of sample extracted, mg

Compound

Mean, XXX

RSD r

, %

Mean, min

RSD r

, %

N

W-IV

2096

2

1327044

0.70

15.43

0.33

1503

2

949877

0.01

15.39

0.02

754

2

478702

0.20

15.45

0.72

W-V

2096

2

1096086

0.77

19.60

0.25

1503

2

788419

0.88

19.54

0.02

754

2

398268

1.22

19.61

0.55

WF-A

2096

2

3021467

0.71

20.28

0.21

1503

2

2163270

0.69

20.23

0.01

754

2

1091661

0.04

20.29

0.48

12-D

2096

2

1512283

0.05

21.31

0.15

1503

2

1081855

0.84

21.26

0.00

754

2

543382

0.45

21.32

0.39

W-A

2096

2

1110624

1.20

22.17

0.14

1503

2

790581

1.17

22.13

0.01

754

2

387811

2.12

22.18

0.34

W-B

2096

2

337372

0.54

25.49

0.06

1503

2

240698

0.88

25.45

0.00

754

2

121812

1.27

25.49

0.23

recommended that the following system suitability checks be performed with each run: ( 1 ) the repeatability (RSD) of peak areas from triplicate injections of mixed standard preparation at 50 μg/mL; ( 2 ) the relative retention times of standards; ( 3 ) the resolution between withanoside V and withaferin A peaks; ( 4 ) the tailing factor for each analyte; and ( 5 ) the r 2 from the plot of peak area versus concentration for each standard

analyte (must be ≥0.998). Note that the QC-check sample is not commercially available, however if desired, laboratories can develop their own QC-check sample following the procedure described above. If the system suitability requirements are not met, the composition of the mobile phase can be adjusted or a new LC column used to meet system suitability before analyzing samples.

Table 10. Repeatability precision of withanolide content in samples with replicate injections of the sample solution Sample Weight extracted, mg N Parameter W-IV W-V WF-A 12-D W-A W-B Sum WS/06Lot08 1552 3 Mean, % w/w 0.92 0.65 0.66 0.28 0.23 0.07 2.80 RSD r , % 0.82 1.63 0.92 0.93 0.92 0.87 1.04 WS/06Lot10 1536 3 Mean, % w/w 0.91 0.62 0.62 0.27 0.21 0.06 2.68 RSD r , % 0.17 0.97 0.09 0.22 0.28 0.93 0.32 WS/05Lot20 5048 3 Mean, % w/w 0.07 0.04 0.08 0.02 0.02 0.01 0.24 RSD r , % 4.48 4.55 5.01 6.84 4.76 10.83 4.62 WS/05Lot21 1527 3 Mean, % w/w 0.48 0.31 0.41 0.12 0.10 0.03 1.45 RSD r , % 0.21 0.75 0.14 0.46 0.00 0.00 0.22 RD/1170 1503 3 Mean, % w/w 0.85 0.59 0.70 0.33 0.23 0.08 2.78 RSD r , % 1.36 1.65 1.00 1.22 1.51 0.76 1.30 RD/1045 1653 3 Mean, % w/w 0.61 0.36 0.40 0.25 0.13 0.04 1.79 RSDr, % 0.67 0.73 1.08 0.93 0.88 1.36 0.79 RD/1162 4336 3 Mean, % w/w 0.15 0.09 0.10 0.02 0.02 0.00 0.39 RSD r , % 1.01 0.64 1.00 2.79 2.34 0.00 0.92 ERH-46 4229 3 Mean, % w/w 0.18 0.15 0.15 0.04 0.04 0.01 0.57 RSD r , % 1.13 1.03 0.79 1.40 1.40 0.00 1.07