Determination of water content in municipal sludge by multiple headspace extraction gas chromatography.

This paper reports a new method for the determination of sludge water content by a multiple headspace extraction gas chromatographic (MHE-GC) method. It is based on measuring the GC signals for the water vapor in a sample vial from the first five headspace extractions, from which the water content in the sludge sample can be extrapolated according to the established calculation equation. The results show that the method has a good repeatability (the relative standard deviation is less than 1%) and accuracy. The maximum relative difference is less than 16% compared to the reference method. The present method is very simple and efficient, and suitable for rapid sample testing in related applications.