Evaporative Concentration of Substances Listed in the European Water Framework Directive (2000/60/EC and 2008/105/EC). A Performance Comparison Between an Automated System and a Manual System

Abstract

App Note 7/2012

Having to reach ever lower limits of detection is a daily challange in modern laboratories. In order to succeed in obtaining sufficiently sensitive analysis methods, sample preparation techniques such as Solid Phase Extraction (SPE) or Liquid-Liquid Extraction are often used as concentration steps. The concentration factor achieved in these cases depends on the amount of solvent used for analyte elution from the SPE cartridge or for liquid extraction. Following the extraction step, further concentration of analytes can be achieved by reducing the amount of solvent left in the extract. This is typically achieved by evaporation. Such a concentration step can contribute significantly to improved limits of detection for the overall analytical method. For the evaporative concentration step, commercially available rotary evaporators as well as custom solutions are widely used. These are mainly stand-alone systems for manual operation. The GERSTEL MultiPosition Evaporation Station (mVAP) in combination with the GERSTEL MultiPurpose Sampler (MPS) now offers fully automated concentration of sample extracts. The system enables complete automation of all sample preparation steps including introduction to an a LC or GC system. The evaporation is controlled by controlling the applied vacuum leading to reproducible results independent of the solvent used. The user can also benefit from a real increase in laboratory efficiency, since batches of samples can be processed automatically overnight. In this Application Note we demonstrate the performance of the mVAP and compare the results with those obtained using a commercially available evaporation system based on nitrogen flow.