The presence of volatile organic compounds (VOCs) in drinking water can have a significant effect on consumer experience. The naturally occurring compounds geosmin, 2-methyl isoborneol (2-MIB) and 2,4,6-trichloroanisole (2,4,6-TCA) have particularly strong odours, and are often the source of complaints to water companies, while the emerging odorants 2-isopropyl-3-methoxypyrazine (IPMP) and 2-isobutyl- 3‑methoxypyrazine (IBMP) are also of concern. Reliable detection of these compounds is therefore important, but this is challenged by their low odour thresholds, which are typically at the low-ppt level.
In this study we demonstrate the fully automated sampling and detection of the five above-mentioned odorants at ppt levels in water using two headspace techniques based on the principle of sorptive extraction – namely, solid-phase microextraction (SPME) and high-capacity sorptive extraction using HiSorb™ probes. In both cases, samples are extracted and preconcentrated on a focusing trap using the new cryogenfree Centri® automated multi-mode platform, and analysed by GC–MS operating in SIM mode. Excellent performance is achieved using both sampling techniques, and we show how this allows analysts using Centri to make the best choice depending on the specific requirements of the application.
Experimental
Samples:
Calibration standards (Sections 1–8):
To assess the linearity of response for the calibration standards, a 100 ppm (100 μg/mL) stock solution of 2-isopropyl-3-methoxypyrazine (IPMP), 2-isobutyl-3-methoxypyrazine (IBMP), 2-methylisoborneol (2-MIB), 2,4,6-trichloroanisole (2,4,6-TCA) and geosmin was volumetrically diluted using HPLC-grade methanol to provide seven concentrations in the range 1–100 ppt. The standard was spiked into 10 mL of water in a 20 mL headspace vial containing Na2SO4 (2.5 g, 25% w/v), and crimp-capped.
>> Download the full Application Note as PDF
Newsletters
Receive the latest pathology news, personalities, education, and career development – weekly to your inbox.
