Determination of 3-Nitrophenol and 4-Nitrophenol in Surface Water by High Performance Liquid Chromatography Combined with Fluorescence Detector after Online pre-Column Reduction
A method for determination of 3-nitrophenol and 4-nitrophenol in surface water by high performance liquid chromatography combined with fluorescence detector after online pre-column reduction was proposed.500 mL of water sample was placed into a separating funnel,and 30 g of sodium chloride was added.The pH of the mixture was adjusted to less than 2 with 10%(mass fraction)hydrochloric acid solution.40 mL of a mixture of dichloromethane and ethyl acetate at a volume ratio of 1∶1 was added,the mixture was shaken for 5 min and then settled,and the organic phase was collected,which was extracted repeatly 3 times.The organic phases were combined,and dehydrated with anhydrous sodium sulfate.The extract was collected,and rotary evaporated to near dryness at 40℃under 79 kPa.The residue was re-dissolved and made its volume up to 1.0 mL with methanol.Hypersil GOLD chromatography column was connected with a zinc powder reduction column of packing particle size of 70 µm,and methanol solution containing 0.39 g·L-1 acetic acid,0.53 g·L-1 zinc acetate,and 0.083 g·L-1 copper sulfate was used as mobile phase for separation.The reduction products of 3-nitrophenol and 4-nitrophenol were determined by fluorescence detector.As shown by the results,linear relationships between the peak areas of the corresponding reduction products and mass concentrations of 3-nitrophenol and 4-nitrophenol were found within 10-100 µg·L-1,with detection limits(3S/N)of 3.0,1.5 µg·L-1,respectively.Test for recovery was made by the standard addition method,giving results in the range of 80.0%-92.6%,with RSDs(n=6)of the determined values not more than 11%.
high performance liquid chromatographyfluorescence detectoronline pre-column reductionnitrophenol
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