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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
Compound
Weight of sample
extracted, mg
N
Peak area
Retention time
Mean, XXX
RSD
r
, %
Mean, min
RSD
r
, %
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
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
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.
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