[Determination of seven nitrobenzene compounds in water samples by single-drop microextraction with capillary gas...

A method suitable for the extraction of nitrobenzene, nitrotoluenes and nitrochlorobenzenes from water samples using single-drop microextraction with capillary gas chromatography is presented. Parameters, such as organic solvents, drop volume of organics, agitation, immerge depth of needle point, aqueous sample volume, exposure time and temperature were controlled and optimized. The developed protocol was found to yield a linear calibration curve in a concentration range from 0.8 to 32 microg/L for nitrobenzene and nitrotoluenes and a range from 0.04 to 3.2 microg/L for nitrochlorobenzenes (r2 > 0.999). The limits of detection were found to be in the range between 0.01 and 0.3 microg/L. The relative standard deviations (RSDs) and relative recoveries (n = 5) from tap water fortified samples were 3.1% -7.9%, and 101% - 105%, and from waste water fortified samples were 3.3% - 7.9%, and 92.5% - 97.0%, respectively. The single-drop microextraction is proved to be a environmental friendly, sensitive, fast and simple tool for the preconcentration of trace nitrobenzene, nitrotoluenes and nitrochlorobenzenes from water samples.