Development of a static headspace gas chromatographic procedure for the routine analysis of volatile fatty acids in wastewaters

• Published in: Journal of Chromatography A 2002-02, Vol.945 (1), p.195-209
• Main Authors: Cruwys, J.A, Dinsdale, R.M, Hawkes, F.R, Hawkes, D.L
• Format: Article
• Language: English
• Subjects: Analytical chemistry; Applied sciences; Calibration; Chemistry; Chromatographic methods and physical methods associated with chromatography; Chromatography, Gas - methods; Exact sciences and technology; Fatty Acids - analysis; Gas chromatographic methods; Industrial Waste; Other wastewaters; Pollution; Temperature; Volatile fatty acids; Volatile organic compounds; Wastewaters; Water Pollutants, Chemical - analysis; Water treatment and pollution
• ISSN: 0021-9673
• DOI: 10.1016/S0021-9673(01)01514-X

An optimised procedure has been developed for the routine analysis of volatile fatty acids in wastewater matrices, using static headspace gas chromatography with flame ionisation detection. Factors such as sample volume, sample pre-treatment and the time and temperature of sample equilibration have been included in an optimisation model designed to provide maximum detector response for acetic, propionic, iso- and n-butyric and iso- and n-valeric acids in the concentration range 0–1000 mg/l. Optimal headspace conditions were observed when equilibrating at 85 °C for 30 min, using a 2.0 ml sample volume with the addition of 1.0 ml of NaHSO 4 (62%, w/v) into standard 22.3 ml vials. 2-Ethylbutyric acid was used as an internal standard. The suitability of ordinary least squares regression and weighted least squares regression models for the purposes of calibration and quantification were investigated. A weighted least squares linear regression model applied to the heteroscedastic data provided lower detection limits, e.g. 3.7 and 3.3 mg/l for acetic and propionic acids.