Validation of a gas chromatography/thermal conductivity detection method for the determination of the water content of oxygenated solvents

A gas chromatographic (GC) method for the determination of the water content of acetone solutions containing methyl isobutyl ketone (MIBK) and other by-products of MIBK synthesis was developed and validated. Linearity is demonstrated (R2 = 0.9999) over a broad range of water concentrations in acetone ranging from 0.04 to 15.2% (w/w). The quantitation limit (QL) of this technique was found to be 0.346% (w/w) and the detection limit (DL) was estimated to be 13 ppm. Validation of this analytical methodʹs accuracy against a coulometric Karl Fischer titration (KFT) method showed excellent agreement between these two techniques. The GC/TCD method is accurate to within a relative error of 3.49% with respect to the KFT method for water concentration above the QL. However, the analysis of six samples below the QL showed an average relative error of 10.96%. Consequently, the KFT method is recommended for the moisture analysis of samples for water concentrations below 0.35% (w/w). Excellent precision is realized for water concentration above the QL (RSD ≪ 0.8%). Good precision (RSD = 1.1%) was obtained for the sample with the lowest water concentration investigated (0.04%, w/w). Repeatability, robustness and excellent specificity of this technique are demonstrated.