Hydrodistillation-liquid-phase microextraction for infrared analysis of food

A combination of hydrodistillation (HD) and liquid-phase microextraction (LPME) has been successfully developed to improve sensitivity and selectivity in attenuated total reflection (ATR) infrared determination of semivolatile organic compounds from high water content plant and food matrices contributing to solve extraction efficiency drawbacks. The HD sampling facilitates the extraction of the semivolatile analytes from the sample matrix compared to headspace sampling, while the liquid-phase microextraction using a water immiscible solvent allows analyte preconcentration prior to ATR analysis. Experimental conditions regarding temperature and time of extraction, water effect and number of consecutive extractions have been deeply studied. The qualitative and quantitative capability of the developed methodology has been evaluated through the identification of the main semivolatile substances in plant and food matrices like spices and citrus peels and the effect of different drying treatments on the volatile composition of rosemary samples was studied through the quantification of camphor and eucalyptol.