Gas chromatography/Fourier transform infrared spectroscopy for determining traces of methane from biodegradation of methylmercury

A sensitive and specific technique, gas chromatography/Fourier transform infrared spectroscopy (GC/FTIR), has been used to detect traces of methane from the biodegradation of methylmercury due to the detoxification process of Pseudomonas putida strain FB1, which was isolated from cinnabar mines in southern Tuscany (Italy). The cured strain FB4 was used together with uninoculated samples as controls for the experiment. The calibration curve of methane was linear up to 1.3 ..mu..g/mL when 0.3 mL of headspace was injected into the GC/FTIR. The detection limit of methane determination in the closed system was 10 ng/mL. The biodegradation of methylmercury was measured during the 130-min experiment by means of elemental mercury analysis, which was determined specifically in the headspace by atomic absorption spectroscopy (AAS), by methylmercury analysis, and by consideration also of the growth rate of the bacterial strains.