| An investigation into analysis of alkyl sulfonates without ultraviolet absorption by high performance liquid chromatography was carried out. The purpose of this research is to develop simple, rapid and reliable methods to determine alkyl sulfonates by high performance liquid chromatography. This study mainly contains three parts:Firstly, a novel analytical method was developed for the determination of pentanesulfonate and heptanesulfonate without ultraviolet absorption using imidazolium ionic liquid as the background ultraviolet absorption reagents by reversed-phase high performance liquid chromatography-indirect ultraviolet detection. Chromatographic separation was performed on a reversed-phase C18 column using imidazolium ionic liquid –methanol as mobile phase. The effects of the background ultraviolet absorption reagents, detection wavelength, column temperature, organic solvents and flow rate on the determination of alkyl sulfonates were discussed. The retention rules of the alkyl sulfonates under different chromatographic conditions were formulated and the chromatographic conditions were optimized. The optimized chromatographic conditions for the determination of pentanesulfonate and heptanesulfonate were as follows: 0.7 mmol/L 1-emyl-3-methyl-imidazolium tetrafluoroborate aqueous solution(pH 3.0, adjusted with 2 mmol/L monosodium phosphate-phosphoric acid)- methanol(55:45, v/v) as mobile phase, flow rate 1.0 mL/min, detection wavelength 210 nm, column temperature 30℃. Under these conditions, two alkyl sulfonates could be successfully separated in 10 min. The detection limits(S/N = 3) of two alkyl sulfonates were 0.24 mg/L and 0.75 mg/L. The relative standard deviations(n = 5) were 0.52% and 1.23%. The method has been successfully applied to the determination of environmental water samples. Recovery of two alkyl sulfonates after spiking was 98.3% – 99.1%. Relative standard deviations of two alkyl sulfonates was less than 1.4%。The method was simple, accurate and reliable.Secondly, a method was developed for the determination of long chian alkyl sulfonates(decane-1-sulfonate, dodecyl-1-sulfonate) without ultraviolet absorption by high performance liquid chromatography- indirect ultraviolet detection using a packed C18 column with imidazolium ionic liquids as the background ultraviolet absorption reagents. The effects of the background ultraviolet absorption reagents, detection wavelength, column temperature, organic solvents and flow rate on the determination of alkyl sulfonates were investigated. The optimized chromatographic conditions for the determination of decane-1-sulfonate and dodecyl-1-sulfonate were as follows: 0.7 mmol/L 1-butyl-3-methyl-imidazolium tetrafluoroborate aqueous solution– acetonitrile(55:45, v/v) as mobile phase, flow rate 1.0 mL/min, detection wavelength 210 nm and column temperature 35℃. Under these conditions, two alkyl sulfonates could be successfully separated in 5 min. The detection limits(S/N = 3) of two alkyl sulfonates were 0.21 mg/L and 0.60 mg/L. The relative standard deviations(n = 5) were 0.52% and 1.23%. The calibration curve showed good linearity over the tested range from 1 to 100 mg/L and from 2 to 100 mg/L for the two alkyl sulfonates. The method was applied in the determination of the 84-disinfectant, with spiked recoveries of 90.85 % – 96.16% and relative standard deviations less than 2.6%. The method was simple, accurate and reliable.Finally, a comparison was performed for the determination of decane-1-sulfonate, dodecyl-1-sulfonate and pentanesulfonate, heptanesulfonate using different types of ultraviolet absorption reagents(anionic UV absorption reagents: 5-sulfosalicylic acid, p-toluenesulfonic acid, potassium hydrogen phthalate; cationic UV absorption reagents: N-pyridin-hexyl bromide, imidazolium ionic liquid) by high performance liquid chromatography-indirect ultraviolet detection. Chromatographic separation was performed on a reversed-phase C18 column. The retention and detection response values were compared as well as to explore the mechanism of the peak by using 0.7 mmol/L background ultraviolet absorption reagents – acetonitrile(55:45, v/v) and 0.7 mmol/L background ultraviolet absorption reagents –methanol(60:40, v/v) as mobile phase. By comparing the result, we obtained that under anionic background UV absorption reagents conditions, alkyl sulfonate eluted negative peaks; under cationic background UV absorption reagents conditions, alkyl sulfonate are eluted positive peak. Using the cationic ultraviolet absorption reagent is better than using anionic background UV absorption reagents. |
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