Quantification of five effective components in pesticides by visible near-infrared spectroscopy

Importance of the topic

Pesticides are widely used in agriculture and public health to control pests and vectors of disease but require precise quantification of active ingredients to ensure safety compliance and limit human exposure risks. Conventional HPLC methods are accurate but involve toxic solvents lengthy analysis times and skilled operators. Visible near infrared spectroscopy offers a fast non destructive and solvent free alternative capable of rapid quality control with minimal sample preparation.

Objectives and study overview

This study evaluates visible near infrared spectroscopy for the quantification of five pesticide effective components namely Abamectin emulsifiable concentrate EC Emamectin EC Cyhalothrin EC Cypermethrin and Glyphosate. For each analyte between 18 and 35 samples were prepared covering typical concentration ranges from about 1.5 to 40.5 wt percent to establish calibration models and assess predictive performance.

Methodology and Instrumentation

Sample spectra were collected in transmission mode on a NIRS RapidLiquid Analyzer over the full 400 to 2500 nm range using disposable glass vials of 4 mm diameter. The Vision Air 2.0 software was used for data acquisition data management and model development. Partial least squares regression with internal leave one out cross validation was applied after selecting wavelength regions specific to each compound.

Main results and discussion

Abamectin calibration employed the 1360 to 1850 and 2050 to 2500 nm regions with a two factor PLS model achieving R2 of 0.9946 and standard errors of calibration and cross validation of 0.05 and 0.06 wt percent. Emamectin used 1300 to 1790 nm with a one factor model R2 of 0.9911 and errors of 0.61 and 0.62 wt percent. Cyhalothrin exploited 400 to 1080 and 1300 to 2200 nm in a two factor model R2 0.9952 and errors of 0.05 wt percent. Cypermethrin and Glyphosate models covered 1300 to 2200 and 1300 to 2170 nm respectively with one to two factor calibrations yielding R2 above 0.995 and errors below 0.03 to 0.16 wt percent. External validation against HPLC confirmed prediction residuals generally within plus minus 0.1 to 0.7 percent and relative standard deviations under five percent.

Practical benefits and applications

Visible near infrared spectroscopy enables rapid non destructive analysis without organic solvents reducing analysis time cost and the need for highly trained staff It can be implemented in routine quality control workflows for pesticide manufacturing and regulatory compliance checks.

Future trends and potential applications

The approach is expected to expand to additional agrochemicals and formulations Portable and miniaturized NIR instruments combined with advanced multivariate calibration transfer and machine learning techniques will allow real time field testing and inline process monitoring to further enhance production efficiency and safety assurance.

Conclusion

Visible near infrared spectroscopy provides a reliable high throughput alternative to HPLC offering comparable accuracy while significantly reducing analysis time solvents and operational costs making it a valuable tool for modern pesticide quality control.

Reference

• World Health Organization Pesticides Health Topics
• World Health Organization Pesticide Residues in Food Fact Sheet
• Wikipedia contributors Pesticide article