Capillary electrochromatography–mass spectrometry determination of melamine and related triazine by-products using poly(divinyl benzene-alkene-vinylbenzyl trimethylammonium chloride) monolithic stationary phases

In this study, a capillary electrochromatography (CEC) method coupled either with UV or mass spectrometric detection was developed for the detection of trace-amounts of melamine and its related by-products (ammeline, ammelide, and cyanuric acid). A series of poly(divinyl benzene-alkene-vinylbenzyl trimethylammonium chloride) monolithic columns, which were prepared by a simple in situ polymerization with divinyl benzene (DVB), vinylbenzyl trimethylammonium chloride (VBTA) and different types of alkene monomers such as 1-octene, 1-dodecene or 1-octadecene were used as separation columns, with the poly(DVB-1-dodecene-VBTA) monolith as the optimal chromatographic material because it provided a better separation. The detection limits of four melamine derivatives were in the ranged of 0.6–2.18 mg L−1 by the optimal CEC–UV mode, and were reduced from 2.2 to 19.4 μg L−1 by the optimal CEC–MS mode. Finally, the proposed CEC methods successfully determined melamine contaminations (0.1 mg L−1 per analyte) in several dairy products as test samples with analyte recovery range of 69–85% (intra-day) and 68–75% (inter-day), and with peak area reproducibility range of 4.3–8.6% and 8.7–15.6% for intra-day and inter-day, respectively. This is the first report for CEC separation coupled with MS detection applied in trace melamine residue analyses with a faster separation and comparable or even better detection ability than previous GC–MS, CE–MS, as well as LC–MS methods.

Figure optionsDownload as PowerPoint slideHighlights
► Detection of trace-amounts of melamine and its related by-products by CEC–UV or CEC–MS.
► Stationary phases used were a series of poly(divinyl benzene-alkene-vinylbenzyl trimethylammonium chloride) monoliths.
► Optimization of mobile phase compositions and MS parameters for melamine separation and detection.
► The optimized CEC method determined melamine contaminations in dairy products.