1. Adequate flow rate If your method does not have a predefined flow rate, start with 5mL/min for pre-conditioning. Sample loading can be set to 10-15mL/min on 6mL reversed-phase SPE cartridges and 5-8mL/min on 6mL anion-exchange SPE cartridges. Final elution can be set to 3-5mL/min. These flow rates can be set directly on our SPE systems. 2. Proper SPE cartridge drying Check that nitrogen supply is turned on and effectively drying the SPE cartridges. Start with 20psi and 2.0L/min and follow similar drying duration as your manual extraction. Increasing the drying time, pressure and flow rate may improve recoveries for some analytes, whereas certain shorter chain and volatile compounds can be lost from excessive drying. 3. Adding soak time Soak time can be added to steps such as pre-conditioning and elution to allow for better solvent interaction with sorbent material and analytes. 4. Controlled evaporation temperature Fraction evaporation can lead to analyte losses if the evaporator temperature is set too high. Follow method recommendations if available. 50 degrees celsius has been found to work well when extracting PFAS.
5. Elution optimization Some compounds might be retained in the SPE cartridges. Besides adding soak time, try reducing the flow rate or increase the amount of solvent used during elution. The SPE-03 system allows the collection of a 2nd fraction to determine the benefits of an additional elution. 6. Sample preparation Ensure that correct solvents, preservatives and pH adjustment are added to your samples. Sometimes contamination or expiration of the standards and preservatives can lead to sudden changes in recovery. 7. Sample container rinsing Some compounds such as long-chain PFAS, PAH and PCBs tend to adhere to sample containers. Depending on the configuration, our SPE systems can perform automatic bottle rinsing and shaking to recover these compounds.
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