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摘要
The col-linear double pulse laser induced breakdown spectroscopy(Laser induced breakdown spectroscopy, LIBS) technology was used to detect fenthion in solution. The fenthion solution was enriched with graphite. The LIBS spectra of samples were obtained by double channel high-precision spectrometer. The carbon spectral line(C Ⅰ 247.856 nm) was used as internal standard to adjust spectral line of 210-260 nm. Then, the competitive adaptive reweighted sampling(Competitive adaptive reweighted sampling, CARS) was used to screen important variable wavelengths which related to fenthion. Finally, the least squares support vector machine(Least squares support vector machine, LSSVM) was used to establish the calibration model of fenthion, and the model was compared with the standard calibration model which established by the basic calibration method and the internal standard method. The results show that the col-linear double pulse LIBS technique can be used to detect the content of fenthion in solution. Optimum calibration model's fitting degree R2 of basic calibration method is 0.935 04. The prediction relative error(Prediction relative error, PRE) of prediction samples is 41.50%. While fitting degree R2 of internal standarad method is 0.993 61, and PRE of prediction samples is 14.91%. What's more, fitting degree R2 of internal standard and CARS-LSSVM method is 0.998 6, and PRE of prediction samples is 8.06%. Comparing the three types of calibration models, it can be found that the internal standard and CARS-LSSVM calibration model has the best performance. The calibration model which established by internal standard method is second. And the calibration model which established by the basic calibration method is the worst. It can be seen that the CARS method can effectively screen the important variables which related to fenthion. Internal standard method combined with CARS and LSSVM methods can improve calibration model's performance and improve the accuracy of predicting.
