Determination of heterocyclic aromatic amines by capillary electrophoresis coupled to mass spectrometry using in‐line preconcentration

Abstract

This paper shows the potentiality of capillary electrophoresis (CE) coupled to mass spectrometry (MS) for the analysis of heterocyclic aromatic amines obtaining good results in terms of sensitivity and precision. These compounds have a special interest since they can be carcinogenic for humans. The optimization of a CE-MS method was performed and the best conditions were obtained using a 16 mM formic acid/ammonium formate solution at pH 4.5 with 60% methanol as running electrolyte. For CE-MS coupling, a sheath liquid methanol/20 mM formic acid (75/25) solution at a flow rate of 3 microL/min and hydrodynamic injection of methanol mixtures for 10 s were used. Detection limits ranging from 18 ng/g to 360 ng/g and precisions up to 1.4% and 12% for migration time and concentration, respectively, were obtained. In order to improve sensitivity, field-amplified sample injection was applied as an in-line preconcentration method. Methanol/5 mM formic acid (50/50) as a sample solvent, 3 s hydrodynamic injection (0.5 psi) of a methanol plug, and 25 s of electrokinetic injection (10 kV) of the sample were found to be the optimum conditions. Detection limits up to 25 times lower and similar precisions than those reported for hydrodynamic injection were obtained.

Recent advances in the application of capillary electrophoresis with mass spectrometric detection

“…HAAs, compounds showing strong mutagenic potencies in bacterial tests and laboratory animals, can be formed during the cooking process of protein rich foods. Sentellas et al [152] presented a CE-MS method for the separation and detection of 16 HAAs. Two herbicides and their major metabolites were determined in wheat using CE-MS with a sheathless-ESI interface and polyacrylamide coated separation capillaries by Goodwin et al [153].…”

Quantitation in capillary electrophoresis-mass spectrometry

“…The closer the concentration comes to the LOQ, the lower is the resulting precision, due to rising variances in the integration [72][73][74]. In other words, when molecules with a low ion yield are being quantified, the precision is lower, compared to an analyte with higher ionization efficiency at the same concentration, due to the difference in S/N [4,75].…”

Recent advances in capillary electrophoresis and capillary electrochromatography of pollutants

“…A significant number of CE-ESI-MS applications have been described for determining pesticides and herbicides [45][46][47][48][49][50][51], pharmaceuticals [52,53], heterocyclic amines [54][55][56][57], explosives [58], amines [59], carboxylic acids [60], or substituted methoxy phenols and aromatic acids [61]. However, the application of CE-ESI-MS to various environmental problems is limited by the use of nonvolatile buffer components and organic additives, such as surfactants and chiral compounds, for achieving a wide variety of separations.…”

“…This online sample preconcentration, generally referred to as stacking, is based either on the manipulation of differences in the electrophoretic mobility of analytes at the boundary of the sample and BGE zones with differing resistivities, or on the partitioning of analytes into a stationary or pseudostationary phase. Among these techniques, field-amplified stacking injection (FASI) [54,55,59,80,82,83,89], large-volume sample stacking (LVSS) [76,[90][91][92][93][94], pH-mediated sample stacking [73,[95][96][97], on-column transient ITP (tITP) [98][99][100][101][102][103][104][105][106], sweeping [89,90,95,[107][108][109][110][111], and online chromatographic preconcentration [52,55,56,106,112,113], have been the most attractive. For example, tITP has been reported to be a valiable online preconcentration method for the focusing of trace ionic species injected from highly saline matrices [104,114].…”

“…The use of CE with MS detection for determination of heterocyclic amines was reported by several groups [54][55][56][57]. For example, Sentellas et al [54] developed a method for the determination of 16 heterocyclic amines.…”