Solid phase extraction (SPE) is a widely used, proven method for sample preparation and sample clean-up in the field of forensic analysis. A number of SPE products are available that offer various sample preparation functions and cover a wide range of procedures. Most SPE products require relatively large volumes of solvent leading to increased time for sample processing, increased cost per sample and higher limits of detection.
Disposable Pipette Extraction (DPX) was developed as an alternative to traditional SPE, combining effi cient and rapid extraction with signifi cantly reduced solvent consumption. DPX is a novel dispersive solid-phase extraction device that uses sorbent loosely contained in a pipette tip to efficiently mix with sample solutions. The main advantages of DPX technology are the extractions are very rapid, recoveries are high, negligible solvent waste is generated, and the extractions can be fully automated and coupled to chromatographic injections.
This study focuses on the automated extraction of small sample volumes coupled to LC/MS/MS in order to provide high throughput analysis of an extended list of benzodiazepines. Using a GERSTEL MPS 2 autosampler, DPX extractions of a variety of biological matrices were performed, using a mixed-mode cation exchange (DPX-CX) sorbent. The resulting eluents from the automated DPX extractions were then introduced into an Agilent 6410 LC/MS/MS instrument.
Coupling DPX to LC/MS/MS provides rapid, just-in-time sample preparation for high throughput analysis. Data show the use of an Agilent 6410 LC/MS/MS instrument to be a highly sensitive procedure for the analysis of benzodiazepines with limits of quantitation of 0.5 ng/mL, and good linearity. The DPX extraction removes potential matrix interferences and ion suppression, and high sensitivity is therefore achieved.
