Development and validation of an LC-MS/MS method for determination of phencyclidine in human serum and its application to human drug abuse cases

Abstract

A new analytical method was developed and validated for the rapid determination of phencyclidine (PCP) in human blood and serum. Rapid chromatographic separation decreased the analysis time relative to standard gas chromatography (GC)-based methodologies. The method involved the use of solid-phase extraction for sample preparation and cleanup followed by liquid chromatography tandem spectrometric (LC-MS/MS) analysis and an electrospray-ionization (ESI) interface. PCP was quantified using multiple-reaction-monitoring with deuterium labeled PCP (PCP-d5) as an internal standard. The method was validated for accuracy, precision, linearity, and recovery. The method was accurate with error <14% and precision with coefficient of variation (CV) <5.0%. The assay was linear over the entire range of calibration standards (r2 > 0.997). The recovery of PCP after solid-phase extraction was greater than 90% with the lower limit of detection (LLOD) for PCP in 500 µl of human serum after solid-phase extraction at 0.06 ng ml−1. This method was used to determine the levels of PCP in postmortem human blood samples. The LLOD in blood was 1 ng ml−1. Blood PCP concentrations were also determined separately using GC and flame ionization detection (FID). Blood calibration standards and serum calibration standards yielded similar concentrations when used to quantitate authentic human blood samples that tested positive for PCP under the GC-FID method. Extraction of PCP from serum required fewer steps and therefore could be used as a calibration matrix in place of blood. The LC-MS/MS methodology shown here was higher throughput compared with GC-based methods because of very short chromatographic run times. This was accomplished without sacrificing analytical sensitivity.

Rapid screening and identification of non-target flavonoid components in invasive weeds by LC/MS-IT-TOF

“…contains multiple types of avonoid components, the manual identication of its components was not an easy task, which needed multiple testing technologies including HSCCC, HPLC, ESI-MS, 1 H NMR, and 13 C NMR analysis; the manual process was time-consuming and largely dependent on experienced knowledge. Moreover, manual analysis would ignore the lower content of avonoid components, making the detected result incomprehensive.…”

“…It has been well acknowledged that hybrid mass spectrometers have been widely utilized to identify the compounds in complex matrixes in many areas without isolated individual compounds. [11][12][13][14] Among these, hybrid ion trap/time-of-ight mass spectrometry coupled with high performance liquid chromatography (LC/MS-IT-TOF) is especially expected to be the most powerful tool for structurally characterizing unknown compounds, in view of its complementary capacity for providing both the MS n ability of an IT and the high resolution and mass accuracy capabilities of a TOF. [15][16][17] However, using LC/MS-IT-TOF to identify non-target components in complicated matrixes would generate a large quantity of fragmentation information and result in a new challenge of information processing.…”

“…The prominent advantage of this strategy is the complete non-target or semi-target identication. Using this approach, we have successfully characterized the avonoid components including the avonoids using manual analysis by HSCCC, HPLC, ESI-MS, 1 H NMR and 13 C NMR analysis 2,5,21 in the invasive weed Flaveria bidentis (L.) Kuntze (F. bidentis). The present approach is reliable and applicable to the identication of non-target avonoids in invasive weeds.…”

LC‐MS in analytical toxicology: some practical considerations

“…Chilling the precipitation reagent prior to use may increase recovery of analytes and improve reproducibility (Choo et al ., 2007). For whole blood and other ‘dirty’ sample matrices, a PPT step is often employed—sometimes with ultrasonication—before the supernatant is subjected to SPE (Kristoffersen et al ., 2007; Marin et al ., 2008; Mercerolle et al ., 2008; Chimalakonda et al ., 2010; Wu et al ., 2010).…”

“…However, the variability appeared to be related to the matrix rather than to the method of extraction. Differences have also been seen in the recovery of PCP from serum and from whole blood (Chimalakonda et al ., 2010) after extraction using mixed‐mode SPE, and attempts to improve the LOD by reducing the volume of solvent used in the final reconstitution step failed, possibly due to incomplete dissolution of the analyte, and/or concentration of ion‐suppressing matrix components.…”