[Rapid determination of N-methyl, propyl-morpholinium cation by ion-pair chromatography on monolithic column with...

A fast analytical method was developed for the determination of N-methyl, propylmorpholinium cation (MPMo) without UV absorption group by ion-pair chromatography-indirect UV detection. Chromatographic separation was performed on a reversed-phase silica-based monolithic column using background UV absorption reagent aqueous solution-ion-pair reagent aqueous solution-organic solvent as the mobile phase. The effects of the background UV absorption reagent, detection wavelength, ion-pair reagent, organic solvent, column temperature and flow rate on the determination of MPMo were investigated. It was found that the morpholinium cation could be determined well with (0.5 mmol/L 4-aminophenol hydrochloride-0.1 mmol/L 1-heptanesulfonic sodium) aqueous solution-methanol (9:1, v/v) as mobile phase at the UV detection wavelength of 230 nm, the column temperature of 30 degrees C and the flow rate of 1.0 mL/min. Under these conditions, the retention time of MPMo was 2.966 min. The limit of detection for MPMo was 0.07 mg/L (S/N = 3). The relative standard deviations (n = 5) for the peak area and retention time were 2. 1% and 0.02%, respectively. The method was successfully applied to the determination of morpholinium ionic liquid synthesized by a chemistry laboratory. Recovery of MPMo after spiking was 98.8%. The results showed that this method is simple and rapid.