This is the Final Summary Overview of the methodology and findings of a study that assessed the efficiency and effectiveness of three alternative sample-preparation techniques that are designed to require fewer steps than traditionally used multi-step solid phase extraction (SPE A) and liquid-liquid extraction (LLE).
The study compared supported liquid extraction (SLE), dispersive solid-phase extraction (dSPE), and modified solid phase extraction (SPE B). The assessment of these three sample preparation methods compared their ability to achieve greater productivity in less or equivalent time compared to traditional techniques, as well as the ease of their introduction into existing laboratory workflows. Solvent usage and cost analyses were also performed. The project extracted 26 drugs and metabolites in blood and urine in small volumes, using SPE, dSPE, LLE, and SLE). Interlaboratory comparison was used to determine whether changes in the work environment affected the reliability of the methods or resulted in a bias. Methods for each drug class, matrix, and sample preparation technique were developed with guidance from product vendors to ensure optimal extraction. After completion, each method was validated at both laboratories to assess the efficacy and reliability of the developed methods. Overall, dSPE was completed in the least amount of time, and LLE took the longest time. SPE A, SPE B, and SLE required similar lengths of time. Since most forensic laboratories are familiar with multi-step SPE, SLE and modified SPE can be easily implemented; dSPE required the longest training time. Information is also provided on extraction solvent/reagent use and disposal and extraction cost. 19 tables, 2 figures, and 5 dissemination listings l