Determination of methanol in pulp washing filtrates by desiccated full evaporation headspace gas chromatography

This paper reports on a desiccated full evaporation headspace gas chromatographic (FE HS-GC) technique for determination of the methanol content in dilute mill effluents. Anhydrous K2CO3 was selected as the preferred salt for eliminating the water in the sample in the headspace sample vial. The results showed that the addition of 12 g K2CO3 made it possible to introduce a larger sample size (up to 1 mL) into the FE HS-GC measurement, thereby increasing the sensitivity of the technique. At the given equilibration temperature (105 °C), a near-complete mass transfer of methanol from the liquid phase to vapor phase (headspace) was achieved within 10 min. Replicate samples showed that the relative standard deviation of the method was less than 1.5%. Further, the limit of quantification (LOQ) was 0.12 μg and the recovery ranged from 95 to 104%. The present method greatly improves the methanol detection sensitivity in the FE HS-GC method and has the added advantage of being simple, rapid and accurate.