Determination of Phenol in Hypersaline Groundwater by Continuous Flow Analysis Method

BACKGROUNDDetermination of phenol by the continuous flow analysis method is seriously compromised if the contents of chlorides or nitrates are greater than 0.4g/L in groundwater. Large amounts of HCl and NO₂ during in situ distillation increase the acidity of product after condensation and cause the failure of buffer solution. In addition, distiller pipes can be easily blocked when the salt content is greater than 0.15% in groundwater. Current methods cannot be widely used because of these limitations.

OBJECTIVESTo establish an easy and convenient way to detect phenol, especially in groundwater samples with high salt content.

METHODSUsing 3% KH₂PO₄ and 3% citric acid solution as distillation solvents eliminated the interferences caused by chlorides (≤ 20g/L) and nitrates (≤ 1g/L). 50% glycerol used as the solvent of distillation reagent alleviated the pipeline blockage in the distiller. This method can be applied to determine groundwater samples with a salinity content of less than 40g/L.

RESULTSThe calibration curve showed good linearity with the correlation coefficient higher than 0.9999 in the range of 0.002-0.100mg/L. The recoveries obtained by adding phenol standards to samples ranged from 95.2% to 104.6%. The relative standard deviation (n=6) was less than 5%. The method detection limit was 0.001mg/L.

CONCLUSIONSThe method is suitable for the determination of phenol in high salt groundwater samples.