Feasibility study on ultrasound-assisted emulsification microextraction-near infrared spectroscopy technique for the determination of traces of nonylphenol in water samples

An ultrasound-assisted emulsification microextraction-near infrared spectroscopy (USAEME-NIR) technique was applied for quantitative analysis of traces of nonylphenol in water samples. Development of the USAEME procedure included optimisation of some important parameters such as extracting temperature, time for ultrasonic-assisted emulsification and the ionic strength. Under optimised conditions, 200 mu L carbon tetrachloride was injected into a 20 mL water sample and ultrasonically emulsified for 15min. The organic phase was taken for NIR analysis after centrifuging. Using a least squares-support vector machine regression (LS-SVMR) model, the linearity and accuracy were satisfactory in the range of 600-6000 mu g Promising results, with r(2)=0.99, RMSEP=44.8 mu g L-1 and RPD=8.9, were achieved when the model was used to analyse for nonylphenol in water samples from local factories and sewage treatment works. The results showed that rapid determination of trace contaminants in water samples by NIR is feasible using the USAEME-NIR technique.