Attenuated total internal reflectance Fourier transform infrared (ATR-FTIR) spectroscopy was used for the investigation of sorption of aqueous solutions of analytes into polymer coatings. A series of simple model polymers: poly(dimethylsiloxane) (PDMS), poly(epichlorhydrin) (PECH), and poly(isobutylene) (PIB) films and analytes: aqueous solutions of ethylbenzene, xylenes, toluene, and nitrobenzene were used to evaluate the use of ATR-FTIR spectroscopy as a screening tool for sensor development. The ratios of integrated infrared absorption bands provided a simple and efficient method for predicting trends in partition coefficients. Responses of polymer-coated guided shear horizontal surface acoustic wave (SH-SAW) sensor platforms to the series of analytes, using polymer coatings with similar viscoelastic properties, were consistent with ATR-FTIR predictions. Guided SH-SAW sensor responses were linear in all cases with respect to analyte concentration in the tested range. Comparison of ATR-FTIR data with guided SH-SAW sensor data identifies cases where mass loading is not the dominant contribution to the response of the acoustic wave sensor. ATR-FTIR spectra of nitrobenzene, coupled with computational chemistry, provided additional insight into analyte/polymer interactions.

The photodegradation of the imidazolinone herbicides imazamox, imazapic, imazaquin, and imazamethabenz-methyl has been investigated in phosphate-buffered solutions and buffered solutions containing natural organic matter (NOM). The hydrolysis of imazamethabenz-methyl, the only imidazolinone herbicide susceptible to hydrolysis, was also examined. The rate of hydrolysis of imazamethabenz-methyl increased with increasing pH, with the para isomer degrading more rapidly than the meta isomer. All photodegradation rate constants increased with pH and plateaued after pH 5.2. All imidzaolinones degraded more quickly under 253.7 nm lamps as compared to degradation under 310 nm lamps. Imazamox and imazapic degraded more rapidly than imazaquin at all pH values and had higher quantum yields. In addition, imazamox and imazapic quantum yields increased as a function of pH, whereas imazaquin quantum yields showed no trend as a function of pH. Photodegradation reaction rate constants decreased as the concentration of NOM was increased in the solutions due to the effect of light screening. Formulas for the proposed photoproducts for imazamox, imazapic, and imazaquin in pH 7 phosphate buffers were identified, and structures for the photoproducts are proposed.

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