Validation of a gas chromatography–mass spectrometry isotope dilution method for the determination of 2-butoxyethanol and other common glycol ethers in consumer products

A gas chromatography–mass spectrometry isotope dilution (GC–MS ID) method was developed and tested for the determination of 14 common glycol ethers in consumer products. Stable isotope labelled standards, 2-methoxyethanol-D7 and 2-butoxyethanol-13C2 (CDN isotopes) were employed to enhance the accuracy and precision of the glycol ethers determination. A 1000-fold sample dilution with methanol was applied to avoid column overload and contamination. At this dilution matrix effects were in most cases negligible and did not interfere with the analysis. The instrument detection limit (IDL) for analysed compounds varied from 0.01 to 1 μg/mL; while the estimated limit of quantification (LoQ) varied between different glycol ethers from 0.02 to 3.4 μg/mL. Calibration was tested in the range of 0.1–200 μg/mL and showed that the linear fit is upheld from 0.1 to 10 μg/mL, and extends beyond this range for some of the analytes. Recoveries of glycol ethers from products with different matrices were similar. The recoveries varied from 87% to 116% between the analysed compounds, while measurements precision varied between 2% and 14%. The method is applicable to products with glycol ether concentrations above 0.002–0.2% (w/w). The concentration range can be extended below the specified limits by decreasing the dilution factor; however, with lower dilution the sample matrix effect is expected to be stronger. Products with very high concentrations of glycol ether (>20%) may need to be further diluted prior to injection to avoid column overload. The method can be used for testing liquid and aerosol products designed for household use, such as cleaners, paints, solvents and paint stripers, for compliance and enforcement of regulations which limit glycol ethers content.