A 'Dilute and Shoot' Liquid Chromatography-Mass Spectrometry Method for Multiclass Drug Analysis in Pre-Cut Dried Blood Spots

Parallel Reaction Monitoring Mode for Atenolol Quantification in Dried Plasma Spots by Liquid Chromatography Coupled with High-Resolution Mass Spectrometry

In this study, we reported a rapid, sensitive, robust, and validated method for atenolol quantification in dried plasma spots (DPS) by liquid chromatography with high-resolution mass spectrometry (LC-HRMS) using parallel reaction monitoring mode (PRM). Aliquots of 25 µL human plasma were placed onto Whatman 903 Cards and air-dried. Disks (3.2 mm internal diameter) were punched, and a 100 µL working internal standard solution was added to each sample and then incubated on a shaker for 15 min at 40 °C, followed by rapid centrifugation (10,000× g, 10 s). The supernatant was transferred into 300 µL vials for subsequent LC–HRMS analysis. After chromatographic separation, atenolol and the internal standard were quantified in positive-ion parallel reaction monitoring mode by detection of all target product ions at 10 ppm tolerances. The total time of the analysis was 5 min. The calibration curve was linear in the range of 5–1000 ng/mL with interday and intraday precision levels and biases of <14.4%, and recovery was 62.9–81.0%. The atenolol in DPS was stable for ≥30 days at 25 and 4 °C. This fully validated method is selective and suitable for atenolol quantitation in DPS using LC–HRMS.

Direct multiclass desorption electrospray ionization-tandem mass spectrometry method for the analysis of sleep inducers and ototoxic drugs in dried blood spots

RATIONALE

An unconventional and innovative approach for the quantitative determination of 11 ototoxic and narcoleptic drugs in whole blood is described. The multiclass method allows the inclusion of the most widespread drugs on the market (antihistamines, antidepressants, antihypertensives, anxiolytics, opioids, Z-drugs) responsible for 10% of occupational accidents.

METHODS

The developed procedure involved the use of the desorption electrospray ionization (DESI) interface for the direct analysis of dried blood spots (DBS). All the issues strictly connected to the chemical-physical characteristics of DBS and DESI (sample inhomogeneity, DBS support, DESI geometry and solvent) were carefully evaluated and innovative strategies were applied. Haematocrit was managed using a small and measured volume of blood (2 μL) with analysis of the entire DBS.

RESULTS

The proposed method was fully validated in terms of limits of detection, limits of quantitation (LOQs; between 60 pg/mm² and 1.6 ng/mm² ), linearity (one order of magnitude starting from LOQs) and inter- and intra-day precision (on three levels, with relative standard deviation values not exceeding 17%). Accuracy was calculated by comparison with an ultrahigh-performance liquid chromatography-tandem mass spectrometry method (suitable also as a confirmatory method).

CONCLUSIONS

Results showed a surprising sensitivity, demonstrating that this procedure could be suitable for applications in various fields, e.g. forensic analysis. Moreover, as a collateral benefit, it was discovered that the method is able to analyse very light traces left on plastic and glass surfaces by detached dried blood.

Thermal desorption bridged the gap between dielectric barrier discharge ionization and dried plasma spot samples for sensitive and rapid detection of fentanyl analogs in mass spectrometry

Guided by finite element simulations and 3D-printing, we constructed a semi-covered flat-TD surface for sufficient thermal desorption and ionization of fentanyl analogs from dried plasma/blood spot samples.