Research Article
Simultaneous Determination of 15 Sulfonate Ester Impurities in Phentolamine Mesylate, Amlodipine Besylate, and Tosufloxacin Tosylate by LC-APCI-MS/MS
Table 2
Stability of sample solutions after 24 h in different matrices and precisions of the 15 sulfonate esters at two concentration levels (n = 6).
| | | Sample solution stability | Precision | | A24 h/A0 h in different matrices | Precision at different levels (RSD, %) | | Methanol with 0.25% HAc | Phentolamine mesylate tablet | Amlodipine besylate tablet | Tosufloxacin tosylate tablet | LOQ | 50 ng/mL |
| | Methyl methanesulfonate | 1.07 | 1.06 | 1.14 | 1.15 | 6.2 | 5.6 | | Ethyl methanesulfonate | 1.03 | 1.13 | 1.03 | 1.01 | 4.8 | 3.7 | | Propyl methanesulfonate | 1.07 | 1.04 | 1.08 | 0.99 | 4.0 | 4.0 | | Isopropyl methanesulfonate | 1.17 | 1.15 | 0.99 | 1.14 | 4.1 | 5.4 | | Butyl methanesulfonate | 1.20 | 1.05 | 1.05 | 1.01 | 5.7 | 4.0 | | Methyl benzenesulfonate | 1.09 | 1.08 | 1.11 | 1.05 | 5.6 | 2.3 | | Ethyl benzenesulfonate | 1.12 | 1.09 | 1.19 | 1.04 | 6.5 | 3.8 | | Propyl benzenesulfonate | 1.04 | 0.92 | 0.95 | 0.94 | 6.6 | 4.5 | | Isopropyl benzenesulfonate | 1.09 | 1.03 | 1.09 | 0.97 | 4.9 | 3.5 | | Butyl benzenesulfonate | 1.14 | 1.07 | 1.03 | 0.98 | 6.0 | 3.9 | | Methyl p-toluenesulfonate | 1.07 | 1.10 | 1.00 | 1.01 | 5.3 | 1.2 | | Ethyl p-toluenesulfonate | 1.15 | 1.04 | 1.03 | 1.04 | 6.0 | 4.0 | | Propyl p-toluenesulfonate | 1.04 | 1.00 | 1.12 | 1.01 | 6.9 | 4.3 | | Isopropyl p-toluenesulfonate | 1.12 | 0.98 | 1.06 | 1.05 | 4.4 | 1.3 | | Butyl p-toluenesulfonate | 1.15 | 1.14 | 1.03 | 0.94 | 5.8 | 3.9 |
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