Coupling Laser Diode Thermal Desorption with Acoustic Sample Deposition to Improve Throughput of Mass Spectrometry–Based Screening

Abstract

The move toward label-free screening in drug discovery has increased the demand for mass spectrometry (MS)-based analysis. Here we investigated the approach of coupling acoustic sample deposition (ASD) with laser diode thermal desorption (LDTD)-tandem mass spectrometry (MS/MS). We assessed its use in a cytochrome P450 (CYP) inhibition assay, where a decrease in metabolite formation signifies CYP inhibition. Metabolite levels for 3 CYP isoforms were measured as CYP3A4-1′-OH-midazolam, CYP2D6-dextrorphan, and CYP2C9-4′-OH-diclofenac. After incubation, samples (100 nL) were acoustically deposited onto a stainless steel 384-LazWell plate, then desorbed by an infrared laser directly from the plate surface into the gas phase, ionized by atmospheric pressure chemical ionization (APCI), and analyzed by MS/MS. Using this method, we achieved a sample analysis speed of 2.14 s/well, with bioanalytical performance comparable to the current online solid-phase extraction (SPE)-based MS method. An even faster readout speed was achieved when postreaction sample multiplexing was applied, where three reaction samples, one for each CYP, were transferred into the same well of the LazWell plate. In summary, LDTD coupled with acoustic sample deposition and multiplexing significantly decreased analysis time to 0.7 s/sample, making this MS-based approach feasible to support high-throughput screening (HTS) assays.

Laser Desorption/Ablation Postionization Mass Spectrometry: Recent Progress in Bioanalytical Applications

“…Compared with LC‐MS/MS, LDTD‐APCI permitted a more than 20‐fold reduction in assay analysis time while the data accuracy remained comparable. The analysis time has been further accelerated by coupling acoustic sample deposition with LDTD (Haarhoff et al, 2016). This methodology enabled screening of CYP metabolites and reaction mixtures for CYP acoustically deposited onto stainless steel well plates in an analysis time of 2.14 to 0.8 s/sample while providing no inferior analytical performance to the established online solid‐phase extraction based method.…”

Current status and future prospects for enabling chemistry technology in the drug discovery process

“…It has sampling speeds of one sample every six seconds. Indirect thermal desorption of sample occurs using a precisely controlled laser diode and ions are then transported to a mass analyzer 113 . Acoustic mass spectrometry is a new technology which was recently highlighted at the 2016 Society for Laboratory Automation and Screening meeting.…”

Development of a High-Throughput Affinity Mass Spectrometry (AMS) Platform Using Laser Diode Thermal Desorption Ionization Coupled to Mass Spectrometry (LDTD-MS)

“…The LDTD method combined with typical liquid handling robotics is compatible with low sample volumes, requires minimal sample preparation, requires no SPE or similar separation step, uses no high-maintenance fluidics, and consumes only minor amounts of solvent, making it an ideal platform for an AMS approach. 24–26 In this study, we also evaluated positive-ion-mode time of flight (TOF) and Sequential Window Acquisition of All Theoretical Mass Spectra (SWATH-MS), a data-independent acquisition method, for compound identification. In LDTD-TOF and LDTD-SWATH acquisition methods, the instrument acquires TOF MS for a select mass range followed by sequential MS/MS scans of predivided mass range over a fixed accumulation and cycle time.…”