Practical Considerations Using Quantisal® Oral Fluid Collection Devices and SPE Method Development by Polymeric Mixed-Mode Cation Exchange

Significance of the Topic

Saliva offers a noninvasive and hard-to-adulterate matrix for drugs of abuse screening. Rapid oral fluid collection using devices like Quantisal simplifies sampling for forensic, clinical and roadside testing while preserving labile compounds prior to analysis.

Objectives and Study Overview

This study evaluated recovery and matrix effects for 85 drugs of abuse and related compounds using the Quantisal collection device combined with mixed-mode cation exchange SPE. Various surrogate matrices (water, synthetic oral fluid) and patient samples were compared. Thirteen wash solvent mixtures were assessed to optimize analyte yields and minimize matrix interferences.

Methodology and Instrumentation

• Sample collection: Quantisal Oral Fluid Collection Device with buffer salts and surfactants.
• Surrogate matrices: HPLC grade water and UTAK synthetic oral fluid mixed 1:3 with Quantisal buffer.
• SPE: EVOLUTE EXPRESS CX 60 mg/3 mL tabless cartridges on PRESSURE+ 48 manifold.
• Wash solvents: 13 organic systems including methanol, acetonitrile, isopropanol, acetone, THF, MTBE, DMSO and DMF in aqueous mixtures.
• Elution: DCM/MeOH/NH4OH (78:20:2) followed by nitrogen evaporation and reconstitution in 10% MeOH 0.1% formic acid or with ethylene glycol additive.
• Chromatography: Agilent 1260 Infinity HPLC with 50x3.0 mm, 2.7 μm biphenyl column, 5 min gradient from 10% to 90% 0.1% FA in MeOH.
• Detection: Sciex 4000QTRAP MS in sMRM mode with ESI positive/negative ionization.

Main Results and Discussion

Water surrogate experiments revealed that four aqueous-based wash systems (50% MeOH, MeCN, IPA and acetone) best balanced analyte recovery and detergent removal. Post-column infusion confirmed absence of polyglycol byproducts under these conditions. Synthetic and patient oral fluid extractions showed 50% methanol washes consistently delivered superior recoveries (85–115%) across most drug classes, though matrix effects remained variable. Sensitive analytes with specific pKa and log P values (e.g., certain benzodiazepines and cannabinoids) required tailored wash polarity to preserve ion exchange interactions while limiting analyte loss. Mixed-mode SPE provided robust enrichment, but wash solvent selection must account for sorbent interactions and analyte properties.

Benefits and Practical Applications of the Method

• Streamlined workflow for comprehensive drug panels in oral fluid testing.
• Reduced sample adulteration risk and simplified collection.
• Efficient detergent removal without extensive cleanup.
• Flexibility to tailor wash solvents for diverse analyte chemistries.
• Compatibility with high-throughput LC-MS/MS screening in forensic and clinical laboratories.

Future Trends and Applications

Advances may include novel SPE sorbents for enhanced selectivity, automated sample processing, real-time on-site screening coupling microextraction to portable MS, and expanded biomarker panels for therapeutic drug monitoring and disease diagnostics. Integration of deuterated internal standards and optimized wash strategies can further mitigate matrix effects.

Conclusion

This white paper demonstrates that Quantisal oral fluid collection combined with EVOLUTE EXPRESS CX SPE and appropriate wash solvent selection affords reliable recovery and minimized matrix interferences for a broad range of drugs. Consideration of analyte-specific properties and method optimization ensures robust LC-MS/MS analysis in forensic and clinical settings.

References

1. Aps JK and Martens LC. The physiology of saliva and transfer of drugs into saliva. Forensic Sci Int. 2005;150(2-3):119-131.
2. Kaufman E and Lamster IB. The diagnostic applications of saliva—a review. Crit Rev Oral Biol Med. 2002;13(2):197-212.
3. Nauntofte B. Regulation of electrolyte and fluid secretion in salivary acinar cells. Am J Physiol. 1992;263(6 Pt 1):G823-37.
4. Zhang L et al. Discovery and preclinical validation of salivary biomarkers for breast cancer detection. PLoS One. 2010;5(12):e15573.
5. Lee YH et al. Salivary transcriptomic biomarkers for ovarian cancer detection. J Mol Med. 2012;90(4):427-434.
6. Ballehaninna UK and Chamberlain RS. Biomarkers for pancreatic cancer. Tumour Biol. 2013;34(6):3279-3292.
7. Bosker WM and Huestis MA. Oral fluid testing for drugs of abuse. Clin Chem. 2009;55(11):1910-1931.
8. Coulter C et al. Antidepressant drugs in oral fluid using LC-MS/MS. J Anal Toxicol. 2010;34(2):64-72.
9. Desrosiers NA et al. Quantification of six cannabinoids in oral fluid by LC-MS/MS. Drug Test Anal. 2015;7(8):684-694.
10. Patteet L et al. Determination of antipsychotics in Quantisal-collected oral fluid by UHPLC-MS/MS. Ther Drug Monit. 2016;38(1):87-97.
11. Dams R et al. Matrix effect in LC-MS/MS analysis of illicit drugs. J Am Soc Mass Spectrom. 2003;14(11):1290-1294.
12. Gosetti F et al. Signal suppression in HPLC-MS/MS. J Chromatogr A. 2010;1217(25):3929-3937.
13. King R et al. Mechanistic investigation of ionization suppression in ESI. J Am Soc Mass Spectrom. 2000;11(11):942-950.
14. De Nicolo A et al. Matrix effect management in LC-MS using internal standard normalization. Bioanalysis. 2017;9(14):1093-1105.