Water Technology - Jan 2012

FEATURE Marc Hamel is a director at Horizon Technology Inc Marc has over 20 years of laboratory processes and fluid handling experience He has previously been involved in new product development for automated liquid handling systems used in drug discovery pharmaceutical compound screening and bio fuels analysis Marc can be reached via phone at 603 893 3663 or email mhamel@ horizontechinc com www watertechonline com 19 The automated SPE approach lets the analyst extract up to eight samples at a time while using much less solvent This approach cuts the total cost of processing each sample reduces the time required and minimizes human contact while reducing greatly total solvent emissions to the environment WT these disks where contaminants are captured The disks are then saturated with solvent to elute out the analytes of interest This is a simplified version of the SPE processes that can be fully automated It involves prepping and cleaning the system and extracting the contaminants from the water in a five step process using various solvents such as hexane acetone and others The solvents are then recovered in separate closed collection containers as well as the processed water sample The advantages of the automated SPE method include a much faster process time set up to extraction taking about 26 minutes And it requires just one technician to process multiple samples simultaneously Typical LLE takes several hours and multiple technicians while CLLE uses one technician more complex glassware and up to 24 48 hours to process a single water sample All three methods require solvent recovery technology but the less solvent used for extraction lessens the amount that has to be recovered As mentioned earlier LLE and CLLE methods use anywhere from 180 500 ml of solvent while the SPE method uses a fraction of this amount In addition all waste solvent must be properly disposed of Using a cost of 165 per drum and averaging two drums a month can add savings of 3150 a year on disposal costs The automated SPE reduced solvent method creates a safer working environment for analysts by reducing the chances of solvent exposure Also the automated SPE technology is a closed system which further enhances safety There are many other pluses Cost safety and simplicity are the main ones Another safety example LLE samples are placed in water baths on hot plates and have to be watched closely as the solvent is boiled off At the end of the process almost all of the 180 mls of solvent are released into the atmosphere A technician has to be present to prevent samples from boiling dry Contrast that with an automated SPE and concentration process featuring endpoint detection and shutoff which automatically prevents the samples from accidentally boiling dry Circle 224