PFAS analysis in nondrinking water matrices presents unique challenges to sample preparation. Trace-level analysis of PFAS in surface water and wastewater requires both low background contamination and the ability to handle challenging matrices. Resprep PFAS cartridges allow fast, reliable SPE sample preparation of non-potable waters, such as those covered in EPA Method 1633 for PFAS analysis. The inclusion of both WAX and carbon layers in a single cartridge allows for simultaneous extraction and cleanup. In addition, an optional filter aid prevents the cartridges from clogging when preparing samples that contain high amounts of suspended solids.<\/p>\n\n\n\n
While methods for PFAS analysis in drinking water have been widely used for some time, the absence of methods for non-potable waters using solid-phase extraction (SPE) has led many labs to modify drinking water methods when analyzing surface water and wastewater. To address this, EPA Method 1633 [1], which was finalized in January of 2024, provides a sample preparation approach that includes an SPE extraction using a weak anion exchange (WAX) cartridge manually packed with glass wool and a dispersive carbon cleanup. The manual packing of glass wool and separate carbon cleanup step add extra time, complexity, and risk of introducing contaminants to the sample preparation process, and manually packed wool can increase variation among technicians. Labs interested in streamlining their sample preparation workflows can utilize Resprep PFAS cartridges, which are dual-bed SPE cartridges that contain both WAX and carbon sorbent beds that allow the SPE extraction and carbon cleanup to be accomplished in a single cartridge. An optional filter aid eliminates the need for manual addition of glass wool to handle samples containing solids, and it provides much better performance in preventing clogs.<\/p>\n\n\n\n
Samples for precision, accuracy, and method detection limit (MDL) studies were prepared in polypropylene bottles using 500 mL deionized water spiked with 25 \u00b5L of extracted internal standards (EIS, Wellington Laboratories p\/n MPFAC-HIF-ES) as per EPA Method 1633, Section 11.2.4. Four samples for precision and recovery analysis were spiked with 200 \u00b5L of native PFAS standards (Wellington Laboratories p\/n EPA-1633STK), giving pre-extraction concentrations of 100-2500 ng\/L. Seven MDL samples were spiked with 20 \u00b5L of a 20:1 dilution of the native standard, giving pre-extraction concentrations of 0.5-12.5 ng\/L. Seven blank replicates were prepared for the MDL study as well. The MDL samples were prepared and analyzed over three days.<\/p>\n\n\n\n
Resprep PFAS SPE cartridges (6 mL), which contained 150 mg of 30 \u00b5m WAX and 50 mg of CarboPrep Plus carbon (cat.# 28930), were placed on a Thermo AutoTrace PFAS system. After preparation of the samples and setup of the SPE system, the samples were extracted following the instructions in EPA Method 1633, Section 11.4, which is summarized in Figure 1. After extraction, the extracts were spiked with 25 \u00b5L of non-extracted internal standards (NIS, Wellington Laboratories p\/n MPFAC-HIF-IS).<\/p>\n\n\n