Analysis of melamine resins by capillary zone electrophoresis with electrospray ionization‐mass spectrometric detection

Abstract

A method for the determination of the major components of (methoxymethyl)melamine resins, with quantitative analysis of unreacted melamine by capillary zone electrophoresis (CZE) using electrospray ionization‐mass spectrometry (ESI‐MS) is presented. Using a low background electrolyte (BGE) pH, components are separated according to their charge/ionic radius ratio with a distinctly different separation selectivity compared to the HPLC methods commonly employed in melamine‐resin analysis. The use of a time‐of‐flight mass spectrometer (TOF‐MS) was concluded to be necessary, as the complex samples studied required maximum sensitivity and resolution, which is clearly superior for TOF‐MS detectors over their quadrupole counterparts. A standard curve of free melamine was determined with an R² = 0.999 over a concentration range of an order of magnitude. This method offers the unique separation selectivity of CZE as well as a quicker analysis time, especially for dimers compared to the HPLC methods used to date.