Simultaneous Determination of 15 Sulfonate Ester Impurities in Phentolamine Mesylate, Amlodipine Besylate, and Tosufloxacin Tosylate by LC-APCI-MS/MS

Table 4

Recoveries and RSDs of the 15 sulfonate esters in the three tablets (%, n = 6).

	Phentolamine mesylate tablet				Amlodipine besylate tablet				Tosufloxacin tosylate tablet
	LOQ	RSD	C^a	RSD	LOQ	RSD	C^a	RSD	LOQ	RSD	C^a	RSD
Methyl methanesulfonate	104.9	7.8	97.3	4.5	98.0	12.3	102.3	5.2	100.6	12.6	101.6	6.0
Ethyl methanesulfonate	93.9	10.8	99.8	5.2	102.8	13.8	101.3	6.2	101.1	4.5	104.2	4.5
Propyl methanesulfonate	101.9	12.1	99.2	3.6	101.5	11.9	102.9	6.8	100.5	7.6	94.0	7.1
Isopropyl methanesulfonate	109.0	10.5	99.5	5.3	102.4	10.8	100.4	4.6	98.0	10.8	103.5	3.8
Butyl methanesulfonate	103.4	13.9	104.2	3.9	99.8	7.0	102.0	5.8	101.0	13.5	99.9	3.9
Methyl benzenesulfonate	99.8	8.9	99.9	2.1	101.7	11.8	103.5	3.0	100.9	5.0	99.8	3.3
Ethyl benzenesulfonate	101.5	9.7	96.3	5.0	99.3	12.4	101.4	5.9	98.8	13.6	99.4	3.0
Propyl benzenesulfonate	98.8	9.5	103.2	3.1	98.9	13.3	95.1	5.8	96.9	13.1	105.1	2.8
Isopropyl benzenesulfonate	99.8	6.6	99.3	3.6	100.2	11.6	105.1	6.1	99.9	5.9	104.6	2.9
Butyl benzenesulfonate	96.9	8.2	101.4	2.1	97.1	8.6	92.7	4.9	95.8	5.2	95.3	4.2
Methyl p-toluenesulfonate	103.3	9.2	99.0	1.4	98.2	6.3	100.4	4.7	100.9	3.7	102.8	3.5
Ethyl p-toluenesulfonate	105.4	15.0	103.1	2.4	100.6	4.4	100.1	4.4	106.2	13.9	102.8	3.1
Propyl p-toluenesulfonate	100.3	3.1	101.1	6.6	99.8	9.6	92.0	3.8	100.4	17.9	94.6	2.4
Isopropyl p-toluenesulfonate	96.6	8.4	99.1	2.3	91.6	9.5	90.4	6.6	96.9	14.1	97.1	1.9
Butyl p-toluenesulfonate	102.0	5.6	99.8	2.0	99.9	11.3	97.5	1.4	100.5	12.2	105.2	1.9

^aC: 50 ng/mL methanesulfonate esters and 10 ng/mL benzenesulfonate and p-toluenesulfonate esters.