Direct Analysis of Beer by ICP-AES: A Very Simple Method for the Determination of Cu, Mn and Fe

Abstract.

A very simple method for determination of trace amount of Cu, Mn and Fe in beer by inductively coupled plasma spectrometry (ICP-AES) was developed. The beer was directly introduced into the plasma, without dilution or adding of reagents, via a conventional V-groove nebulizer. The only sample preparation used was degassing of the beer to remove CO₂. By optimizing the ICP-AES parameters (RF power and Nebulizer gas flow rate) and by the appropriate choice of wavelengths for measurements, sufficient accuracy for the determination of the trace metals was obtained. Various types of beers were analysed by the direct ICP-AES method and for comparison, also with two other methods: by GFAAS and ICP-AES after decomposition. No significant difference was found for Cu and Mn (ANOVA, 95% confidence level) using the three methods. This was normally also the case for Fe; only in one case did the result of Fe by the direct method deviate from the other methods (10% lower results). The limit of detection for the direct method was estimated to 1.1, 0.3, and 1.1 ng mL⁻¹ for Cu, Mn, and Fe, respectively.