Abstract
The determination of drugs of abuse in dried blood spots (DBS) has become increasingly popular due to several advantages associated with sample collection and storage compared to other biological matrices. The extraction of dried blood spots typically involves manual intervention. First, a small disc is punched out of the center of a dried blood spot card. Following solvent extraction of the sample, it is also common to include further cleanup using liquid-liquid extraction (LLE) to improve detection limits or exchange solvents for compatibility with subsequent chromatographic separations. Modern analytical labs are looking to automation to help reduce solvent usage and increase sample throughput while ensuring the high quality of the resulting data.
Liquid-liquid extraction of biological samples enables the concentration of analytes of interest as well as their separation from interfering matrix components, resulting in better chromatography and lower detection limits. The automated extraction and determination of drug compounds using the GERSTEL MPS robotic sampler have been previously developed and discussed (1,2,3). As a result of this study, we were able to show that automated liquid-liquid extraction performed by the MPS sampler could successfully be used for drugs of abuse in dried blood spot samples. Compounds isolated from the DBS samples using the automated extraction were then automatically introduced to an Agilent Technologies 1260 HPLC coupled with an Agilent Ultivo Triple Quadrupole Mass Spectrometer with a Jet stream electrospray source, allowing their respective limits of quantitation to be met. Analysis of extracted calibration curves were found to be linear, and the calculation of relative standard errors resulted in %RSE values less than 12.1% for all drug compounds monitored. Accuracy data averaged 99.7% (89.0% – 112%), and precision data averaged 5.83% RSD (2.20% – 14.4%) for all drug compounds extracted from DBS samples.
Keywords:
Sample Preparation, LC-MS/MS, Lab Automation, Drugs of Abuse
