Miniature way to detect PCBs

Swedish chemists develop mini syringe to pick up pollution.

Despite a global ban, poly-chlorinated biphenyls (PCBs) are still causing problems in aquatic ecosystems. There are strict regulations regarding PCB concentrations in both the US and the EU but measuring ultra-trace PCB concentrations can be a tricky business. Now a team of Swedish chemists from Lund University and Uppsala-based life science company Biotage has developed a miniature device to measure PCB levels.

The main problem with analysing PCB levels in water samples is that the compounds have an annoying tendency to stick to the glass surfaces of lab equipment to give inaccurate PCB readings. According to the researchers, the most frequently used sample pre-treatment methods for PCB determination in water (liquid-liquid extraction and solid-phase extraction) ’suffer from many drawbacks’. Even solventless extraction techniques such as solid-phase microextraction have some shortcomings which are linked to absorption problems, they say. The team claims to have overcome such drawbacks by miniaturising the sample-handling step.

Biotage has made a prototype ’extracting syringe’ (ESy) which uses microporous membrane liquid-liquid extraction. Water samples (1 × 10 ^—3 l) are pumped on one side of a porous hydrophobic membrane separating the sample from an organic solvent phase and analytes are extracted at the aqueous-organic interface. The ESy is mounted directly above a gas chromatography (GC) injector so that the organic extract can be transferred directly to the GC. Computer software controls the ESy and triggers the GC system. The team is currently developing a prototype for an automatic card exchanger.

Emma Davies