Capillary electrochromatography-applicability to the analysis of pesticides and compounds of environmental concern and the theory of electroosmosis

Abstract

SummaryThe applicability of capillary electrochromatography to the automated analysis of pesticides and phthalate esters that are of environmental concern was assessed. Reversed phase packing materials were compared. Column to column and run to run reproducibility was established. Peak height with an internal standard gave the best reproducibility. Faster analysis than alternative HPLC methods was demonstrated for a mixture of the insecticide pirimicarb and related pyrimidines. The relationship between the concentration of an analyte in a sample and at the detector was determined by the use of radio-labelled 14C-pirimicarb. The volume fraction of the liquid zone was 0.64. The possibility of electroosmosis through the pores is discussed with reference to the Rice-Whitehead model for electroosmotic flow in a capillary. A new parameter, the effective pore size is used in equations for electroosmosis through porous packings.

Capillary electrochromatography for pesticide analysis: Effects of environmental matrices

“…Such methods have wide scope for development but have yet to become widely adopted. Therefore, at present, in many cases the precision achieved in CEC is at best on the borderline of acceptability for quality control purposes in the manufacture of pharmaceuticals and agrochemicals [12]. Until these practical difficulties are overcome, the most useful applications of CEC are perhaps for qualitative analyses which have a requirement for high resolution, such as identification of impurities or for the analysis of drug and pesticide metabolites.…”

“…Pesticide metabolism studies entail the analysis of xenobiotics in extracts of complex matrices which may give rise to the possibility of fouling the stationary phase [12]. Procedures generally follow guidelines laid down by regulatory authorities such as the Environmental Protection Agency in the USA [13].…”

The analysis of pharmaceutical bases on a silica stationary phase by capillary electrochromatography using aqueous mobile phases

“…These standard stationary phases possess a high population of acidic silanol groups which generate a substantial electro-osmotic flow (EOF) in CEC [2][3][4][5][6]. These standard stationary phases possess a high population of acidic silanol groups which generate a substantial electro-osmotic flow (EOF) in CEC [2][3][4][5][6].…”

“…To date, a range of impressive results have been published for a variety of applications but these have been confined to the analysis of neutral and acidic compounds [2][3][4][5][6]. However, acidic silanol groups which are involved in the generation of the EOF can cause problems in the analysis of bases by CEC.…”

Capillary electrochromatographic analysis of barbiturates in serum

“…Besides, the anionic acids are hardly retained on the stationary phase for RP separation. To overcome these problems, the separation of acidic compounds has been carried out in the ion-suppressed mode at low pH with standard stationary phase (e.g., C 18 ) or mixed-mode phases including ion exchangers (e.g., SCX/C 18 , SAX/C 18 ) [21][22][23][24]. In this study, we employed the ion-suppressed mode and the effects of buffer pH, buffer concentration, and mobile phase composition on the separation of barbiturates were investigated.…”