Analytical Sciences

Improving the Sensitivity of NIR Spectroscopy with an Enrichment Technique: Determining a Trace Analyte of Ethyl Carbamate

Xuemei WEI, Zixia HUANG, Wei ZHANG, and Yiping DU

Center of Analysis and Test, East China University of Science and Technology, Shanghai 200237, China

An exploration was made to develop a determination method of a low-concentration analyte by NIR spectroscopy. An absorber, silica gel was employed to extract and enrich a low-concentration analyte of ethyl carbamate. The solid absorber with the enriched analyte was measured by NIR spectroscopy in the range of 800 - 2500 nm. Afterwards, PLS regression was performed between the NIR spectra and the concentrations of the analyte for quantitative analysis of the low-concentration analyte. The spectra of 20 solid samples of analyte-absorbed silica gel showed a good correlation with the concentrations of ethyl carbamate in the samples. A leave-one-out cross validation was applied to evaluate the prediction ability of PLS models built with the full spectra, spectra in the region of 1920 - 1970 nm and the region of 2250 - 2430 nm, respectively. The values of the root-mean-square error of the cross validation (RMSECV) were about 0.1 mg L^-1 (0.1 ppm).

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