Coated Blade Spray-Tandem MS for Rapid Screening & Quantitation of Drugs in Oral Fluids
Coated Blade Spray is a sample preparation device that can be directly interfaced to mass spectrometry instrumentation for rapid screening and quantitation.
CBS is a coated stainless-steel sheet with the shape of a small sword. It has an ultrathin SPME coating that permits rapid enrichment of small molecules present in a given sample. As a result, the coating provides sample cleanup and prevents the extraction of salts and macromolecules that could cause instrument contamination.
In this poster video, we demonstrate how CBS coupled to tandem mass spectrometry enables rapid screening and quantitation of multiple controlled substances and pain management drugs in samples of oral fluids.
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Hello, my name is German Gomez and I work at Restek in the research and development team. Today I’m going to present my poster “Coated Blade Spray-Tandem Mass Spectrometry for Rapid Screening and Quantitation of Target Drugs in Oral Fluids Samples.”
So, what is “coated blade spray”? Coated blade spray is a sample preparation device that can be directly interfaced to mass spectrometry instrumentation for rapid screening and quantitation. CBS is a coated, stainless-steel sheet with the shape of a small sword. It has an ultrathin SPME coating that permits rapid enrichment of small molecules present in a given sample. As a result, the coating provides sample cleanup and prevents the extraction of salts and macromolecules that could cause instrument contamination.
CBS devices have a pointed tip that allows them to be used as a substrate spray technology. Coated blade spray can generate instrumental signal on a mass spectrometer by supplying a small amount of organic solvent to the coated area of the device and then after a few seconds applying a strong electrical field to the non-coated area of the device, which in turn generates ions from the tip of the CBS via electrospray ionization. In this work, we demonstrate how CBS coupled to tandem mass spectrometry enables rapid screening and quantitation of multiple controlled substances and pain management drugs in samples of oral fluids.
CBS devices coated with HLB particles were used in this work and the coated blade spray analytical protocol comprised three steps: First, analyte enrichment, by extracting from a vial containing the sample of interest; second, coating cleaning, which involved immersing the CBS device in a vial with water for fast removal of any loosely attached matrix components; and third, instrumental analysis, which is performed by applying 10 µL of a methanol/water solution onto the coated area of the blade. After 10 seconds 4 kV were applied to the non-coated area of the blade for 5 seconds, inducing electrospray ionization. Calibration plots were constructed using matrix-matched calibration with an internal standard. Although the internal standard should be preferably the deuterated analogue of the analyte of interest, plenty of studies with CBS devices have shown that for multi-analyte quantitation a handful of standards are more than sufficient to correct for signal drifts or errors during the extraction process. The calibration plots correlated the ratio of the area of analyte and area of internal standard against the concentration of analyte in the sample.
Unlike liquid or gas chromatography, there is no separation of the target analytes from potential interferences in direct-to-MS technologies like coated blade spray. For this reason, analyte collection times via CBS are optimized based on signal-to-noise ratios rather than mere instrumental signal. In this study, we evaluated the effect of the analyte collection time, as well as the potential use of matrix modifiers, so to obtain a higher instrumental response. CBS, as an SPME-based technology, extracts analytes via free concentration. As recently reported by Rickert et al., Khaled et al., and Kasperkiewicz et al., matrix modifiers can be used to enhance the performance of the CBS devices by decreasing the binding of the analytes to the protein and, consequently, increasing the amount of free analyte that can be collected by the coating. As can be seen in Figure 1, the presence of acetonitrile primarily helped with the extraction of the most hydrophobic molecules, which typically have larger binding constants, such as the cannabinoid JWH-015. On the other hand, ACN can drastically reduce the response for more polar compounds such as levamisole. Overall, the use of unmodified oral fluids provided satisfactory quantitation results for all compounds of interest. As portrayed in Figure 2, best signal-to-noise ratios were attained in less than 5 minutes of analyte collection for most target analytes. Consequently, quantitation experiments were performed using this collection time by extracting from 200 µL of oral fluids sample. As can be seen in Figure 3, excellent linearity was obtained for all the analytes of interest.
In conclusion, in this work, we present the first application of coated blade spray tandem mass spectrometry towards the determination of several substances in oral fluids. The optimized CBS-MS/MS method demonstrated outstanding precision with RSD below 10 %, limits of quantitation equal to or below 5 ng/mL, and excellent linearity with correlation coefficients larger than 0.99 for most of the target molecules such as cocaine, fentanyl, EDDP, and fluoxetine. Our results corroborated that best extraction times must be selected on the basis of signal-to-noise ratios, rather than mere instrumental signal as when compare to SPME coupled to LC-MS/MS.
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