The Role of the Carbon Cartridge in the One-Pass System

One of the recent introductions is a system to extract a full range of acid/base neutral compounds from various types of water samples using a One-Pass system. In this case, rather than extract water at pH 2, adjust the pH of the water to 12 and re-extract, the water is passed once through a multi-media SPE disk and then a carbon cartridge before being delivered to waste. The elegance of this approach is the elimination of the basification step, which requires additional labor adjusting the pH and time passing the sample through the disk a second time after the first elution of acids and neutrals. The additional benefit of omitting the basification step eliminates the formation of insoluble metal hydroxides that can restrict the flow of sample through the disk or add significant time if a liquid-liquid extraction is used.