The feasibility of determining low levels of organic solvents in water by near-infrared (near-IR) spectroscopy is investigated. Mixture samples of tributyl phosphate (TBP) and methyl iso-butyl ketone (MIBK) are determined in aqueous solutions over the concentration range of 1-160 ppm. Through the use of C-H combination bands in the region of 5000-4000 cm-1, sufficient selectivity is obtained to determine each compound in the presence of the other. Separate multivariate calibration models are computed for each compound by use of a combination of bandpass Fourier digital filtering and partial least-squares (PLS) regression with both analysis of absorbance and single-beam spectra. A genetic algorithm is used to implement a joint optimization of the parameters governing the filtering and PLS calculations. Through the use of this procedure, a calibration model based on absorbance spectra is computed for MIBK with a standard error of prediction (SEP) of 3.82 ppm over the 1-160 ppm range. This five-term model utilizes the spectral range of 4495-4335 cm-1. A similar nine-term model based on absorbance spectra is computed for TBP over the 4620-4320 cm-1 range. For the range of 1-100 ppm, an SEP of 4.84 ppm is achieved. The results obtained from the analysis of single-beam spectra are comparable with those obtained in the analysis of absorbance data. Calibration models computed with samples prepared in natural water are also found to have a similar level of performance. These results establish the feasibility of using near-IR spectroscopy to screen water samples for solvent contamination.
Qing Ding, Brian L. Boyd, and Gary W. Small, "Determination of Organic Contaminants in Aqueous Samples by Near-Infrared Spectroscopy," Appl. Spectrosc. 54, 1047-1054 (2000)
References are not available for this paper.
OSA is able to provide readers links to articles that cite this paper by participating in CrossRef's Cited-By Linking service. CrossRef includes content from more than 3000 publishers and societies. In addition to listing OSA journal articles that cite this paper, citing articles from other participating publishers will also be listed.