Analysis of methyl tert.-butyl ether and its degradation products by direct aqueous injection onto gas chromatography with mass spectrometry or flame ionization detection systems

Abstract

A method was developed to analyze methyl tert.-butyl ether (MTBE) and its degradation products by gas chromatography with mass spectrometry (GC–MS) or flame ionization detection (FID) with direct aqueous injection. The column had dimensions of 30 m×0.25 mm with film thickness 0.25 μm and a stationary phase of FFAP (nitroterephthalic acid-modified polyethylene glycol). The optimized GC conditions for non-acid components were as follows: carrier gas flow-rate,1 mL/min; oven temperature, 35°C for 5.5 min, ramped to 90°C at 25°C/min, then ramped to 200°C at 40°C/min and held at 200°C for 8 min. The conditions for the acid components were: carrier gas flow-rate, 1 mL/min; oven temperature, 110°C for 2 min, ramped to 150°C at 10°C/min, then ramped to 200°C at 40°C/min. The injection port contained a silanized-glass reverse-cup liner filled with Carbofrit. The minimum concentrations for the linear range for the selective ion monitoring mode were 30 to 100 μg/L, depending on the analytes. The minimum detection limit was 1 mg/L for MTBE and tert.-butanol when using FID. More components could be analyzed with the FFAP-type column than with the cyanopropylphenyl–dimethyl polysiloxane-type column.