Analysis Of Piperidinium Ionic Liquid Cations By Ion-Pair Chromatography With Indirect Ultraviolet Detection

An investigation into analysis of piperidinium ionic liquid cations without ultraviolet absorption by ion pair chromatography was carried out.The purpose of this research is to discuss the effect of different background ultraviolet absorption reagents and ion-pair reagents,and find out the factors and rules that are influence on the separation and detection of ionic liquid cations,and develop simple,accurate and effective method to determine ionic liquid cations.This study mainly consisted of three parts:Firstly,this part focused on the influence of different background ultraviolet absorption reagents on the determination of piperidinium ionic liquid cations by ion-pair chromatography with indirect ultraviolet detection.ZORBAX Eclispe XDB-C18 column and ultraviolet detector were used in this experimentation.Background ultraviolet absorption reagents are divided into cationic?4-aminophenol hydrochloride,1-ethyl-3-methyl imidazolium tetrafluoroborate and N-ethyl pyridinium tetrafluoroborate?,anionic?potassium biphthalate,5-sulfosalicylic acid?and amphiprotic?p-aminobenzoic acid?.The three kinds of ultraviolet absorption reagents were studied in this experimentation.The results showed that piperidinium cations can be separated and detected by cationic and anionic ultraviolet absorption reagent.However,amphoteric can not do.In general,the cationic ultraviolet absorption reagent has the best effect for separation and detection of the piperidinium cations by ion-pair chromatography with indirect ultraviolet detection.Secondly,effect of ion-pair reagent on analysis of piperidinium ionic liquid cations by ion-pair chromatography with indirect ultraviolet detection was studied,and the retention and detection rules were discussed.Ion-pair reagent plays an important role on the separation and detection in ion-pair chromatography.The ion-pair reagents in the study were sodium 1-pentanesulfonate,sodium 1-heptanesulfonate,sodium1-octanesulfonate and sodium 1-decanesulfonate.The results show that with the increase of the lengths of the alkyl chain of ion-pair reagent,the retention time is longer,the detection limit increases overall trend;the higher the methanol content in the mobile phase is,the shorter the retention time is,and the smaller the detection limit is.The retention mechanism with the piperidinium cations is mainly the dynamic ion exchange mechanism in ion-pair chromatography with indirect ultraviolet detection.In a word,whether it is sodium 1-heptanesulfonate and sodium 1-octanesulfonate as ion-pair reagent is the suitable choice for separation and detection of piperidinium cations.Finally,a method was developed for the separation and determination of piperidinium ionic liquid cations in environmental water by solid phase extraction and ion-pair chromatography with indirect ultraviolet detection.Ambient water is staticed,centrifuged and filtered first.Then 10 m L water of ambient were concentrated and purified via a reversed-phase SPE.5 mL 0.8 mmol/L sodium 1-octanesulfonate was added for leaching impurities,and then,1 m L 40%acetonitrile aqueous solution was used to elute the ions that to be measured.Finally,the ion-pair chromatography analysis was conducted on the collected liquids.Chromatographic condition:the column was C₁₈reversed-phase column,mobile phase was 0.5 mmol/L 4-amiophenol hydrochloride-0.1 mmol/L sodium 1-octanesulfonate?75/25 v/v?,flow rate was 1.0 m L/min,column temperature was 30?,indirect UV detection was 210 nm.Under these conditions,the three piperidinium cations were separated within 10 min.The detection limits?S/N=3?were 0.08-0.44 mg/L.The relative standard deviations?n=5?for peak area and retention time were 0.06%and 0.72%respectively.The method has been applies to the determination of piperidinium cations in environmental water.The recoveries of piperidinium cations after spiking were 84.2%⁹5.6%.The method is accurate,reliable,rapid,and has good practicability.It can meet the detection requirements of the piperidinium ionic liquid cations in environment water samples.