This technique requires multiple extractions at 2 different sample pHs and consumes large amounts of organic solvents. EPA method 625.1, an updated version of method 625 has been recently published (by Lemuel Walker, Office of Science and Technology, US EPA) allowing for the use of solid phase extraction (SPE) as an alternative sample preparation technique, if the quality control (QC) acceptance criteria are met.  UCT has been working with the Independent Laboratory Institute (ILI) and others to validate the performance of SPE as compared to LLE.  UCT’s product performed extremely well with clean extracts, low method detection limits and excellent analyte recoveries.  You can download a copy of our application note here:

 https://www.unitedchem.com/sites/default/files/docs/spapplications/5103-01-01_uct_epa_method_625.pdf