Analysis of water in liquid and solid samples by headspace gas chromatography

Summary The water content of solid samples, which are insoluble in organic solvents, is determined by equilibrium headspace gas chromatography after suspending the samples in a water-miscible dry solvent such as ethylene glycol monomethylether. The accuracy of this suspension approach was tested with sodium tartrate-2-hydrate, a calibration standard for the Karl-Fischer titration, and good agreement was found. Partical applications are given for water analysis in an ionic detergent, in paper, and in solid food samples such as instant soup or drink powder and roasted coffee. The preferred calibration procedure was the standard addition technique, but internal or external standard calibration is also possible, particularly in the case of insoluble samples since the water only is extracted into the solvent. The resulting aqueous solution in the organic solvent represents an ideal matrix for all calibration techniques. The suspended particles from the solid sample were found not to cause additional matrix effects.Paper presented partly at the International Symposium Die Bestimmung des Wassers organized by the Fachgruppe Analytische Chemie der GDCH, Hannover, 4–6 November, 1987.Part I: Fresenius Z Anal Chem 336:291–296