Concentration and High Pressure Liquid Chromatographic Determination of Pyrazon in Water

Abstract

Nyagah, G. (1981). Concentration and high pressure liquid chromatographic determination of pyrazon in water. Journal of Chromatographic Science, 19(10), 500-502.

A simple, fast method for extracting and concentrating pyrazon in water using C18 Sep-Pak™ cartridges (Waters Associates Inc., Milford, Massachusetts) and consequently determining the herbicide using high pressure liquid chromatography (HPLC) has been developed. The recovery of pyrazon from water was found to improve considerably when sodium chloride was dissolved in the water. A 500 ml sample of lake water with 25% dissolved NaCl was passed through a C18 Sep-Pak cartridge and the adsorbed pyrazon eluted with about 5–8 ml of dichloromethane. The dichloromethane solution was evaporated under nitrogen and the residue dissolved in methanol. Pyrazon was determined using reverted-phase HPLC with 55% sodium phosphate buffer (0.05 M, pH 5.0) and 45% methanol as the mobile phase. An ultraviolet (UV) detector at a fixed wavelength of 280 nm was used for detecting pyrazon. The detection limit reached was 2 ppb.