Direct multi-elemental analysis of wines by means of microwave-sustained inductively coupled atmospheric-pressure plasma optical emission spectroscopy (MICAP-OES)

• MICAP-OES is a suitable technique for the direct elemental analysis of wines. • MICAP robustness is closer to that shown by ICPs. • Both atomic and ionic emissions are usually enhanced by wine concomitants. • Wine analysis is successfully performed using matrix-matched calibration standards. Elemental analysis of wine samples by means microwave-induced plasma optical emission spectrometry (MIP-OES) is challenging due to both spectral and non-spectral interferences caused by the matrix of such samples. Recently, the microwave-sustained inductively coupled atmospheric-pressure plasma (MICAP) have proposed as a robust plasma source for elemental analysis of complex samples. The aim of this study was to investigate, for the first time, MICAP-OES capabilities for the elemental analysis of wine. Unlike previous MIP cavity designs, wine samples can be directly analysed by means the MICAP due to the high plasma tolerance to organics and salts. Though ethanol and non-volatile organic compounds present in wine gave rise to significant carbon-based spectral interferences, the most sensitive wavelengths of analytes present in wine were not interfered apart from Pb. As regards non-spectral interferences, atomic emission was enhanced up to 50 % by wine matrix major concomitants (i.e., ethanol and potassium) whereas ionic emission enhancement was just limited to 10 %. Interestingly, no matrix effects on the optimum nebulizer gas flow rate were noticed. Therefore, it was feasible to simultaneous determine major, minor and trace elements using a single set of experimental conditions. Detection limits were mostly within the low µg L −1 and they allow the determination of the elements regulated by the international code of oenological practices with the exception of Cd and Pb. The proposed method was successfully validated by analysing a TITRIVIN BTA wine reference material and several wine samples of different composition using matrix matched standards without internal standardization.