Direct Coupling of Bio-SPME to Liquid Electron Ionization-MS/MS via a Modified Microfluidic Open Interface.

Priscilla Rocío-Bautista,Veronica Termopoli,Emir Nazdrajić,Achille Cappiello,Pierangela Palma,Giorgio Famiglini,Janusz Pawliszyn

doi:10.1021/jasms.0c00303

Abstract

We present a modified microfluidic open interface (MOI) for the direct coupling of Bio-SPME to a liquid electron ionization-tandem mass spectrometry (LEI-MS/MS) system as a sensitive technique that can directly analyze biological samples without the need for sample cleanup or chromatographic separations as well as without measurable matrix effects (ME). We selected fentanyl as test compound. The method uses a C18 Bio-SPME fiber by direct immersion (DI) in urine and plasma and the subsequent quick desorption (1 min) in a flow-isolated volume (2.5 μL) filled with an internal standard–acetonitrile solution. The sample is then transferred to an EI source of a triple-quadrupole mass spectrometer via a LEI interface at a nanoscale flow rate. The desorption and analysis procedure requires less than 10 min. Up to 150 samples can be analyzed without observing a performance decline, with fentanyl quantitation at microgram-per-liter levels. The method workflow is extremely dependable, relatively fast, sustainable, and leads to reproducible results that enable the high-throughput screening of various biological samples.

Highlights

Fentanyl and its derivatives have been quantified in biological fluids with gas chromatography− mass spectrometry (GC-MS) or LC-MS.[1−8] In LC-MS/MS, internal standards are used to assess matrix effects (ME) coming from the ionization step
Fentanyl was injected in the flow injection analysis (FIA) mode at the concentration of 100 mg·L−1 in MeOH using a 10 nL loop (1 ng absolute amount)
The following parameters were considered: (1) the flow isolated volume inside the microfluidic open interface (MOI), which must be the smallest possible, and (2) the choice of capillaries based on the internal diameter and length, which must not create excessive pressure on the system and must ensure the least-possible volume for a rapid transfer of the analytes to the MS

Summary

Introduction

Fentanyl and its derivatives have been quantified in biological fluids with GC-MS or LC-MS.[1−8] In LC-MS/MS, internal standards are used to assess matrix effects (ME) coming from the ionization step. The performance of DI-SPME-MOI-LEI-MS/MS was evaluated in water and urine.

Results

Conclusion