Comparison of Whole Blood & Precipitated Blood for the Quantitation of Drugs of Abuse Using PaperSpray

Significance of the Topic

PaperSpray-MS offers a rapid direct approach to quantify drugs of abuse in dried blood spots. This technique reduces sample preparation time increases throughput and supports clinical forensic and industrial applications requiring fast reliable detection of multiple analytes. The comparison between whole blood and protein-precipitated blood provides insights into matrix effects and sensitivity improvements.

Study Objectives and Overview

This study evaluates the quantitation performance of 21 drugs of abuse across three sample matrices neat solvent (methanol) untreated whole blood and blood precipitated with zinc sulfate in methanol. Key goals include assessing the impact of protein precipitation on ion suppression signal intensity and lower limit of quantitation (LLOQ) particularly for protein-binding compounds such as benzodiazepines.

Materials and Methods

• Analytes 21 drugs including benzodiazepines opiates cocaine stimulants and sedatives each with corresponding internal standards
• Sample Preparation Spiked whole blood at concentrations ranging from 5 to 400 ng/mL protein precipitation achieved by adding a 2 1 methanol to 0 2 M ZnSO4 solution 1 3 ratio followed by centrifugation and supernatant collection
• Spotting Aliquots of neat whole and precipitated blood samples were deposited on paper spray plates dried and analyzed in five replicates per calibration level

Instrumentation

• Thermo Scientific VeriSpray PaperSpray ion source coupled to a TSQ Altis mass spectrometer
• Rewetting and spray solvents 95 5 0 01 methanol water acetic acid
• Mass spectrometry parameters optimized spray voltage ion transfer tube temperature 400 °C CID gas pressure and precise MS MS transitions recorded in method files
• Data analysis performed with TraceFinder 5 1 generating 1-minute chronogram integrations and calibration curves

Results and Discussion

• Neat Methanol Uniform LLOQ of 5 ng/mL achieved for all compounds
• Whole Blood Matrix suppression reduced signal intensity and sensitivity LLOQs increased for most analytes due to protein binding and ionization effects
• Precipitated Blood Protein precipitation restored signal for three benzodiazepines alprazolam clonazepam temazepam lowering LLOQs up to 16-fold minimal changes observed for the other 18 drugs
• Calibration Curves Improved linearity and signal-to-noise ratios for challenging analytes in precipitated samples validating the precipitation strategy

Benefits and Practical Applications

• High-throughput screening of multiple drugs of abuse with analysis times under two minutes per sample
• Elimination or simplification of sample cleanup for most compounds reducing labor and consumables
• Enhanced detection of protein-bound analytes via simple zinc sulfate precipitation protocol
• Applicability to clinical toxicology workplace testing forensic investigations and quality control in pharmaceutical research

Future Trends and Potential Applications

• Integration with automated plate loaders and robotic sample handling to further increase throughput and reproducibility
• Expansion to additional analyte classes including novel psychoactive substances and therapeutic drugs
• Development of compact or portable PaperSpray-MS platforms for point-of-care or on-site drug screening
• Utilization of machine learning algorithms for dynamic method optimization and improved quantitation accuracy

Conclusion

The comparative analysis demonstrates that PaperSpray-MS is a sensitive fast and robust method for quantifying a broad range of drugs of abuse in blood. While most analytes are reliably measured without cleanup zinc sulfate protein precipitation significantly improves sensitivity for strongly protein-bound compounds. This workflow supports diverse analytical scenarios demanding rapid accurate results.

References

1. Espy R D et al Paper spray and extraction spray mass spectrometry for the direct and simultaneous quantification of eight drugs of abuse in whole blood Anal Chem 2014 86(15) 7712-7718
2. Chin P K L et al Adult age and ex vivo protein binding of lorazepam oxazepam and temazepam in healthy subjects Br J Clin Pharmacol 2011 72(6) 985-989
3. Pacifici G M et al Plasma protein binding of clonazepam in hepatic and renal insufficiency and after hemodialysis Ther Drug Monit 1987 9(4) 369-373