Simultaneous determination of melamine and related compounds by hydrophilic interaction liquid chromatography-electrospray mass spectrometry.

A hydrophilic interaction liquid chromatography coupled to ESI-MS (HILIC/ESI-MS) method for the simultaneous determination of melamine and related compounds, i.e. ammeline, ammelide and cyanuric acid in foods was developed and validated. The separation was accomplished on a Venusil HILIC column with a mobile phase of acetonitrile + 10 mM ammonium formate buffer solution at pH 3.5 (88:12, v/v) under isocratic elution mode. For the detection of the targets, the ESI probe worked in the positive and negative switching mode. For each compound, three ions were selected as qualitative ions to obtain high specificity, and the most abundant ion of each compound was selected for quantification to obtain high sensitivity. The target compounds were quantified using SIM with 15N3-melamine and 13C3-cyanuric acid being used as an internal standards in the positive and negative modes, respectively. Compared with RP separation mode, HILIC has merits such as high separation and anti-interference efficiency. The method validation including linearity, LOD, LOQ, precision and recovery proved that the method has merits such high sensitivity, specificity and simplicity versus the other methods reported in the literature.