Determination of hydrogen cyanide in residential ambient air using SPME coupled with GC-MS

Hydrogen cyanide (HCN) is commonly released into the atmosphere from vehicle emissions, biomass burning and industrial processes such as gold mining, pesticide production, and chemical manufacturing. The aim of this study was to quantify the ambient HCN concentration in a residential area close to a gold mine using solid-phase micro extraction (SPME) coupled with gas chromatography-mass spectrometry (GC-MS) and calculate it's potential health risks. Air samples were collected at a distance of 0.1, 1.0 and 2.0 km away from the gold mine. All cyanide compounds were extracted using 75 μm carbowax/polydimethylsiloxane-coated SPME fibre and analysed using GC-MS. Calibration curve was constructed using standard concentrations ranged between 5 and 500 μg L−1. This method showed good linearity (r2 = 0.999) and accuracy (recoveries = 84-119%), reproducibility (relative standard deviation < 11.5%) and the LOD was 0.16 ppbv. HCN was detected in 68% of samples ranging between 0.16 and 8.56 ppbv. HCN concentration was significantly higher (p < 0.05) for samples taken at 0.1 km away from the gold mine compared to concentrations at 1.0 and 2.0 km. The non-carcinogenic risk of HCN from air inhalation was negligible as the calculated hazard quotient was less than 1. The method used in this study was sensitive enough to detect ambient HCN concentrations at levels which were below the reference concentration for long term inhalation exposure by the U.S. Environmental Protection Agency (0.72 ppbv) and it used simpler and less time consuming method compared to the conventional sample preparation method, enabling rapid community exposure assessment.