VASE-TD-GCMS: A Solvent Free Analytical Technique for Quantitative Analysis of Pollutants in Water

Daniel B. Cardin, Entech Instruments, Inc. ,CA, USA
Sage J. B. Dunham, PhD, Entech Instruments, Inc., CA, USA
Victoria L. Noad, Entech Instruments, Inc., CA, USA

A diverse range of chemical pollutants such as pesticides, industrial waste, consumer products, and disinfectant by-products are continually introduced into the natural environment resulting in widespread water pollution. Accurate analytical water testing is essential for ensuring that undesirable compounds remain at safe exposure levels. Routine testing is currently performed using a combination of several sample introduction techniques, including purge-and-trap for volatile analytes, and liquid-liquid extraction and SPE for less volatile compounds. Vacuum assisted sorbent extraction (VASE) is a new solvent free headspace sampling technique capable of extraction and pre-concentration of volatile to semi-volatile organic compounds from both aqueous and solid samples for offline chemical analysis. For VASE, an extraction cartridge with a sorbent bed (called a Sorbent Pen) is inserted into a sealed vial containing a sample. The contents of the vial are placed under vacuum to increase analyte volatility and diffusion rates to expedite transfer from the sample matrix onto the sorbent. Once the compounds are concentrated onto the sorbent, the sorbent cartridge is placed into a unique injection port where the sample is preheated and thermally desorbed onto a dual column flow path for GC separation and MS detection, providing quantitative chemical determination for an array of volatile to semi-volatile organic compounds from a single experiment. Calibration curves for a variety of water contaminants including pesticides, polyaromatic hydrocarbons, polyfluoroalkyl substances, disinfectant by-products, and volatile fatty acids are shown. Quantitative data from ground water samples is also presented, demonstrating the potential use of this solvent free headspace extraction technique paired with GCMS for determination of concentrations for a wide range of chemical pollutants found in water.