New HS-SPME-GC-BID method for the determination of volatile constituents in distilled beverages

Abstract

To maintain quality control in the production of distilled beverages, it is necessary to perform several types of chromatographic analysis, where gas chromatography (GC) coupled with mass spectrometry (GC/MS) and flame ionization detector (GC-FID) have been used as traditional analysis techniques for volatile organic compounds. More recently the dielectric barrier discharge ionization detector (BID) has been coupled to GC (GC-BID) which is more sensitive than the FID and the thermal conductivity detector (TCD) for analyzing various volatile compounds. This study aims to develop a new method for determining higher alcohols, n-butanol, and ethyl acetate in cachaça and whisky samples using headspace solid-phase microextraction (HS-SPME) followed by GC-BID. The HS-SPME method was optimization with multivariate analysis. The analytical results were provided by the weighted linear Square (WLS) method for linearity correction, internal standard addition (ISA) as a calibration method for matrix effect correction, reproducibility, recovery and accuracy. The best conditions for extraction of the compounds by HS-SPME were obtained for 50 °C, 20 min and without addition of NaCl. The WLS regression allowed to obtaining satisfactory correlation coefficients (0.9632 to 0.9992). The matrix effect (ME) was verified for n-propanol, isobutanol and isoamyl in both matrices. The recovery values of the cachaça matrix ranged from 81.24 to 106.94 %, except for isoamyl alcohol, and ranged from 82.06 to 106.25 % for the whisky matrix, except for n-butane. The precision ranged from 0.66 to 7.38 % and 0.62 to 6.77 % for the cachaça and whisky samples, respectively. Limit of detection (LOD) values ranged from 0.26 to 0.51 mg L-1, while limit of quantification (LOQ) values ranged from 0.78 to 1.55 mg L-1. The validation process and statistical methods were successfully applied to quality assurance of the analysis of cachaça and whiskey samples, where n-propanol, ethyl acetate, isobutanol and isoamyl were detected for all samples within the maximum content for higher alcohols and ethyl acetate, except n-butanol. The method can be satisfactorily applied to quantify higher alcohols and esters in samples of alcoholic beverages.