Method For Determination Of Esters Research Articles

Extensive Validation of Gas Chromatographic Method for Determination of Esters in Wines Using Monolithic Materials as Preconcentration Step

A comprehensive validation of a quantitative method is a critical issue for food analysis, which requires reliable estimation of uncertainties influencing measurements. Esters as important contributors to fruity aroma generally affect quality of wine and its organoleptic features. In this study, a full validation of the method developed for quantification of esters with uncommon silica monolithic discs and gas chromatographic analysis is presented. Two types of sorbent modification and a few desorption solvents were tested for ester removal from wine samples. Uncertainty contributions from mass balance tolerance, purity of chemicals, volume measurements, calibration curve deviation and extraction procedure were included in the calculation of the combined uncertainty. The expanded uncertainty of ester determination ranged from 15 to 37% and was mainly affected by uncertainty of calibration curve. The proposed method provided a limit of detection and a limit of quantification of 0.005–0.168 μg/L and 0.018–0.560 μg/L, respectively. Additional measurements revealed a recovery range of 70–111%, average reproducibility of instrument response less than 4%, and repeatability of the method below 16% for most of esters.

Colorimetric Method for Ester Content of Alcoholic Beverages

Abstract A colorimetric method for determination of esters in alcoholic products was studied for the effect of procedural variables. It is based on the quantitative reaction of esters with hydroxylamine in alkaline solution to form a hydroxamic acid which, upon acidification, forms a colored complex in the presence of Fe(III) ions. Mathematical data are presented to demonstrate that the colorimetric method is superior to the AOAC saponification method, 9.051-9.052, for comparing samples which contain widely differing ester compositions. The colorimetric method is rapid and requires a small sample.