Simple, fast and inexpensive large “whole water” volume sample SPE-loading using compressed air and finely ground sand

In environmental trace analysis there is often a need to enrich the compounds of interest from a large sample volume, where the use of solid phase extraction (SPE) is more or less the standard technique. The presence of the sample matrix can cause clogging of the SPE-column, especially at the end of a sample load. Swedish surface waters are often humic rich making the use of traditional sample loading by a vacuum manifold very limited. This obstacle forced the development of a different sample loading technique, based on compressed air and sand as an in-line-filter, designed to load larger sample volumes as needed in trace level analysis of hormones in surface water. The developed technique, combined with a UPLC MS/MS method, showed promising reproducibility and accuracy, and enabled increased sensitivity for the analysis of hormones in humic rich surface water.