Rapid Detection of Pesticide Residues in Chinese Herbal Medicines by Fourier Transform Infrared Spectroscopy Coupled with Partial Least Squares Regression

Abstract

This paper reports a simple, rapid, and effective method for simultaneous detection of cartap (Ca), thiocyclam (Th), and tebufenozide (Te) in Chinese herbal medicines including Radix Angelicae Dahuricae and Liquorices using Fourier transform infrared spectroscopy (FT-IR) coupled with partial least squares regression (PLSR). The proposed method can handle the intrinsic interferences of herbal samples; satisfactory average recoveries attained from near-infrared (NIR) and mid-infrared (MIR) PLSR models were <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M1"><mml:mn fontstyle="italic">99.0</mml:mn><mml:mo>±</mml:mo><mml:mn fontstyle="italic">10.8</mml:mn></mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M2"><mml:mn fontstyle="italic">100.2</mml:mn><mml:mo>±</mml:mo><mml:mn fontstyle="italic">1.0</mml:mn></mml:math>% for Ca, <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M3"><mml:mn fontstyle="italic">100.2</mml:mn><mml:mo>±</mml:mo><mml:mn fontstyle="italic">6.9</mml:mn></mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M4"><mml:mn fontstyle="italic">99.7</mml:mn><mml:mo>±</mml:mo><mml:mn fontstyle="italic">2.5</mml:mn></mml:math>% for Th, and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M5"><mml:mn fontstyle="italic">99.1</mml:mn><mml:mo>±</mml:mo><mml:mn fontstyle="italic">6.3</mml:mn></mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M6"><mml:mn fontstyle="italic">99.6</mml:mn><mml:mo>±</mml:mo><mml:mn fontstyle="italic">1.0</mml:mn></mml:math>% for Te, respectively. Furthermore, some statistical parameters and figures of merit are fully investigated to evaluate the performance of the two models. It was found that both models could give accurate results and only the performance of MIR-PLSR was slightly better than that of NIR-PLSR in the cases suffering from herbal matrix interferences. In conclusion, FT-IR spectroscopy in combination with PLSR has been demonstrated for its application in rapid screening and quantitative analysis of multipesticide residues in Chinese herbal medicines without physical or chemical separation pretreatment step and any spectral processing, which also implies other potential applications such as food and drug safety, herbal plants quality, and environmental evaluation, due to its advantages of nontoxic and nondestructive analysis.