This work demonstrates the use of disposable pipette extraction (DPX) as a fast and automated sample preparation technique for the determination of barbiturates and 11-nor-9-carboxy- 9-THC (COOH-THC) in urine. Using a GERSTEL MultiPurpose Sampler (MPS) with DPX option coupled to an Agilent 6460 LC-MS/MS instrument, 8 barbiturates and COOH-THC were extracted and their concentrations determined. The resulting average cycle time of 7 min/sample, including just-in-time sample preparation, enabled high throughput screening.

Validation results show that the automated DPX-LC/MS/MS screening method provides adequate sensitivity for all analytes and corresponding internal standards that were monitored. Lower limits of quantitation (LLOQ) were found to be 100 ng/mL for the barbiturates and 10 ng/mL for COOH-THC and % CVs were below 10 % in most cases.

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Disposable Pipette Extraction (DPX)

Disposable Pipette Extraction (DPX)

Extraction in Seconds

DPX is a fast and efficient SPE technique used for a wide rnge of applications such as drugs of abuse, therapeutic drug monitoring, comprehensive screening, pharmacology studies (NNK), as well as pesticides in fruit and vegetables. DPX is based on unique and patented SPE devices: Pipette tips that incorporate loosely contained sorbent material, which is mixed with the sample solution. Turbulent air bubble mixing creates a suspension of sorbent in the sample ensuring optimal contact and highly efficient extraction. The extraction is performed much faster than with traditional SPE techniques.

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