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aclavik
et al
.:
J
ournal of
AOAC I
nternational
V
ol
.
99, N
o
.
1, 2016
search of these
m/z
values in AIF records can be used to detect
nontargeted, novel PDE5 inhibitor adulterants based on their
structural similarity to known PDE5 inhibitors.
Recovery and Repeatability
Results of recovery experiments conducted in triplicate at
50 mg/kg in a capsule sample in M5 are presented in Table 4.
The test level of 50 mg/kg was selected for this evaluation
to demonstrate the method performance at the target LOQ
of AOAC SMPR 2014.011 for the determination of PDE5
inhibitors (6). The mean recoveries ranged from 69 to 90%.
Only one target compound (thiohomosildenafil) was slightly
below the recovery range of 70–120% provided in AOAC
SMPR 2014.011. This method showed excellent repeatability
with RSD
r
values of 0.4–1.8%, well below the repeatability
criteria of ≤20% in AOAC SMPR 2014.011.
POI
Detection and identification results are summarized in
Table 5. In total, 1575 data points were evaluated to demonstrate
POI and also probability of detection (POD) for detection/
screening of PDE5 inhibitors. Correct detection/identification
results compliant with identification requirements provided
in the European Commission Decision 2002/657/EC (9) were
obtained for all evaluated analytes at all concentration levels
and in all matrixes. The method validation results fulfilled the
Figure 1. Impact of the mobile phase composition on peak shape and chromatographic resolution between isobaric analytes. (A) Mobile
phase A/B: 0.1% FA in H
2
O/0.1% FA in MeOH. (B) Mobile phase A/B: 5 mM ammonium formate in H
2
O/5 mM ammonium formate in ACN. (C)
Mobile phase A/B: 10 mM ammonium formate and 0.1% FA in H
2
O/10 mM ammonium formate and 0.1% FA in ACN:MeOH (1:1, v/v).
Candidates for 2016 Method of the Year
169