Oral fluid for is usually collected with the Quantisal® device or similar. These collection devices contain various components such as buffer salts and surfactants which present particular challenges in sample preparation for LC-MS/MS.
This white paper from Biotage labs examines recovery and matrix effects for 85 common DOAs, when collected using the Quantisal device. Utilizing water, synthetic oral fluid and patient samples as matrixes, the impact of various wash solvents on analyte recovery and matrix effects from the Quantisal buffer, in polymeric mixed-mode cation exchange SPE is investigated.
The frequency distribution analysis using water surrogate for oral fluid narrowed the organic solvent wash landscape using varying degrees of solvent polarity. This allowed for the examination of the direct relationship between the Quantisal buffer, all analytes, and the mixed-mode EVOULTE® Express CX sorbent. Although most analytes were well suited for this sorbent, approximately 45% showed variability. Among the thirteen different combinations of solvents, the entirety of the 85 analytes panel routinely responded to four wash systems (55%), two polar protic (50% MeOH and 50% IPA), two polar aprotic (50% acetone and 50% MeCN) and neat methanol. The four aqueous based solvent wash systems were examined for their ability to provide detergent free extracts, yeilding sound recoveries (85–115%).
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