Solid phase microextraction-gas chromatographic-mass spectrometric determination of nitrous oxide evolution to measure denitrification in estuarine soils and sediments

A SPME-GC-MS method was developed to quantify nitrous oxide (NO) to evaluate denitrification rates. There is a need for this sensitive and definitive N2O detection method to accurately measure the soil and sediment ability to convert anthropogenic mineral nitrogen loads to N-2 through denitrification hence decreasing estuarine waterway pollution loading. This method is applied to measure denitrification, which is a major pathway for inorganic nitrogen removal, by incorporating the acetylene (C2H2) block method on anaerobic assays. Currently, denitrification is largely measured using GCs fitted with TCD or ECD detectors. With a mean R-2 value of 0.996, the calibration curve spanned over three orders of magnitude (4.1-2030 nM) with a limit of detection (LOD) of 4.1 nM N2O (18 ppb) and a limit of quantification (LOQ) of 16 nM N2O (72 ppb). This detection method was valid with less than 15% relative standard deviation (RSD) and error for middle and high quality control (QC) points and less than 20% for low QC points on three experimental days. Measuring N2O using SPME-GC-MS technology allows for confidence in identification, high sensitivity, reproducibility, and short run times. (c) 2006 Elsevier B.V. All rights reserved.