Use of second-order calibration for residue screening of some triazines in the presence of coeluting interferences by gas chromatography-selected ion mass spectrometry

The quantities of residues of some triazines such as prometon, propazine, atrazine and simazine in complex matrices of apple samples were determined, using gas chromatography-selected ion mass (GC-SIM) spectrometry. Generalized rank annihilation method (GRAM) as a second-order calibration technique was used for screening, resolving and finally determining the amounts of the residues. Before the GRAM analysis, different steps of data preprocessing such as background correction, de-skewing and standardization for rank alignment was used for every target analyte. The de-skewing and rank alignment algorithms were used for bilinearity and trilinearity corrections, respectively. The two data matrices needed for the GRAM analysis were obtained from the sample solution, which contained different spiked levels of target analytes, and standard addition solution GC-SIM data. By using the GRAM method we were able to obtain the mass chromatograms and the true ion abundance ratio of each target analyte and precisely quantify the residue amounts of triazines in the different sample solutions by using only one standard data matrix. Unambiguous detection of a target analyte by this method was compared with the traditional approach of measuring peak height that fails to accurately detect the target because of severe coeluting interferences. Finally the method was successfully used for the simultaneous determination of two-target analytes of simazine and atrazine in a sample solution with severely convoluted mass chromatographic profiles.