Browsing by Author "Tan, Guan Huat"

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Chemometric approach to the optimization of HS-SPME/GC–MS for the determination of multiclass pesticide residues in fruits and vegetables
    (Elsevier, 2015-01-09) Abdulra’uf, Lukman Bola; Tan, Guan Huat
    An HS-SPME method was developed using multivariate experimental designs, which was conducted in two stages. The significance of each factor was estimated using the Plackett–Burman (P–B) design, for the identification of significant factors, followed by the optimization of the significant factors using central composite design (CCD). The multivariate experiment involved the use of Minitab statistical software for the generation of a 27–4 P–B design and CCD matrices. The method performance evaluated with internal standard calibration method produced good analytical figures of merit with linearity ranging from 1 to 500 lg/kg with correlation coefficient greater than 0.99, LOD and LOQ were found between 0.35 and 8.33 lg/kg and 1.15 and 27.76 lg/kg respectively. The average recovery was between 73% and 118% with relative standard deviation (RSD = 1.5–14%) for all the investigated pesticides. The multivariate method helps to reduce optimization time and improve analytical throughput
  • Thumbnail Image
    Item
    Multivariate study of parameters in the determination of pesticide residues in apple by headspace solid phase microextraction coupled to gas chromatography–mass spectrometry using experimental factorial design
    (Elsevier, 2013-07-12) Abdulra’uf, Lukman Bola; Tan, Guan Huat
    Solid-phase microextraction (SPME) is a solvent-less sample preparation method which combines sample preparation, isolation, concentration and enrichment into one step. In this study, multivariate strategy was used to determine the significance of the factors affecting the solid phase microextraction of pesticide residues (fenobucarb, diazinon, chlorothalonil and chlorpyrifos) using a randomised factorial design. The interactions and effects of temperature, time and salt addition on the efficiency of the extraction of the pesticide residues were evaluated using 23 factorial designs. The analytes were extracted with 100 lm PDMS fibres according to the factorial design matrix and desorbed into a gas chromatography–mass spectrometry detector. The developed method was applied for the analysis of apple samples and the limits of detection were between 0.01 and 0.2 lg kg1, which were lower than the MRLs for apples. The relative standard deviations (RSD) were between 0.1% and 13.37% with average recovery of 80–105%. The linearity ranges from 0.5–50 lg kg1 with correlation coefficient greater than 0.99