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2 International Letters of Chemistry, Physics and Astronomy

2 2014

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Validation of UV Spectrophotometric and HPLC Methods for Quantitative determination of chlorpyrifos

Zalat O. A., Elsayed M. A., Fayed M. S., Abd El Megid M. K.

International Letters of Chemistry, Physics and Astronomy

2014

Vol. 2

58-63

A specific and sensitive HPLC and UV spectrophotometric methodwere developed for determination and analysis of chlorpyrifos. Chromatographic separation was achieved on a 150 mm x 10 mm I.D. reversed phase column Zorbax SB C-18. usingdeionizedwater: acetonitrile in the ratio of 10:90 v/v respectively as mobile phase. The effluent was monitored at 290 and 230 nm. Two sharp peaks were obtained for the solvent and chlorpyrifos at 2.7 and 3.45 min respectively. UV spectrophotometric method was performed at 290 nm using Isopropanol as the solvent. Linear range was 0.025-3500 ppm (r2 = 0.9986 ±0.0009) for HPLC method and 2.229 to 200 ppm (r2 = 0.9988) for UV spectrophotometric method. Validation guidelines and statistical analysis showed that both the methods were precise, accurate, sensitive, and can be used for the routine quality control of chlorpyrifos in waste discharges.

Sources of uncertainty for the Determination of Chlorpyrifos by Gas Chromatography Equipped with Flame Photometric Detector

Zalat O. A., Elsayed M. A., Fayed M. S., Abd El Megid M. K.

International Letters of Chemistry, Physics and Astronomy

2014

Vol. 6

8--55

Analysts are increasingly being required to evaluate the uncertainty associated with methods. Estimating the uncertainty of an analytical result is an essential part of quantitative analysis. This paper discusses the sources of uncertainty of chlorpyrifos determination by gas chromatography equipped with flame photometric detector (GC-FPD). The analysis was performed on HP-5 MS, 30 m x 0.32 mm capillary column with a 0.25 μm stationary film thickness using ultra pure nitrogen (99.9999 %) as a carrier gas at 25 psi constant pressure. The method has been optimized. Factors affecting quantization of chlorpyrifos such as injector temperature, carrier gas inlet pressure, air to hydrogen ratios and initial temperature program have been studied to get the best sensitivity, minimum delectability. The liner range of the detector was from 0.15 ng/ml to 1200 ppm, the minimum detection limit was 0.15 ng/ml and the relative standard deviation was 0.839.