O.A. Zalat, Mohamed A. Elsayed, M.S. Fayed, M.K. Abd El Megid Megid, Sources of Uncertainty for the Determination of Chlorpyrifos by Gas Chromatography Equipped with Flame Photometric Detector, ILCPA Volume 25, International Letters of Chemistry, Physics and Astronomy (Volume 25)
    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.
    Chlorpyrifos, Injection, Minimum Detectability, Sensitivity