With the aim of improving the throughput of environmental sample analysis, Canadian researchers have recently reported the development of a simple on-line extraction method for the detection of small molecules in drinking, surface, and wastewater samples.

Traditional off-line extraction methods for analysis of pharmaceuticals, pesticides and metabolites in environmental samples often involve tedious sample preparation, resulting in low productivity and sample throughput.  Now, Sébastien Sauvé and his colleagues – with the Department of Chemistry at the Université de Montreal – have developed a new approach using on-line solid-phase extraction in combination with liquid chromatography electrospray tandem mass spectrometry with positive electrospray ionization (LC-ESI(PI)-MS/MS). 

As reported in an advance online publication of the Journal of Environmental Monitoring, the Montreal approach requires the injection of only 1 milliliter of filtered water sample and involves a total analysis time of only 20 minutes (including the time needed to flush the SPE cartridge and recondition the LC column).  The limits of detection for this method ranged from 2 to 24 nanograms per liter for the compounds analysed, which included caffeine, carbamazepine and atrazine.  Recoveries were achieved in the range of 87 to 110% in both surface and wastewater samples.  Although some compounds exhibited matrix effects using this approach, these did not exceed 25%.

Importantly, Sauvé and colleagues were able to analyse over 200 samples without affecting the overall performance of the pre-concentration column.  It is worth mentioning that the group detected the above-mentioned compounds of interest in all water and wastewater samples that were analysed.  This on-line extraction approach should prove useful for laboratories seeking to improve the throughput of their environmental sample analysis.