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Open AccessArticle

A Dual Ligand Sol–Gel Organic-Silica Hybrid Monolithic Capillary for In-Tube SPME-MS/MS to Determine Amino Acids in Plasma Samples

Departamento de Química, Faculdade de Filosofia Ciência e Letras de Ribeirão Preto, Universidade de São Paulo, P.O. Box 14040-901 Ribeirão Preto, SP, Brazil
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Author to whom correspondence should be addressed.
Academic Editors: Constantinos K. Zacharis and Paraskevas D. Tzanavaras
Molecules 2019, 24(9), 1658; https://doi.org/10.3390/molecules24091658
Received: 21 March 2019 / Revised: 17 April 2019 / Accepted: 24 April 2019 / Published: 27 April 2019
(This article belongs to the Special Issue Solid-Phase Microextraction)
This work describes the direct coupling of the in-tube solid-phase microextraction (in-tube SPME) technique to a tandem mass spectrometry system (MS/MS) to determine amino acids (AA) and neurotransmitters (NT) (alanine, serine, isoleucine, leucine, aspartic acid, glutamic acid, lysine, methionine, tyrosine, and tryptophan) in plasma samples from schizophrenic patients. An innovative organic-silica hybrid monolithic capillary with bifunctional groups (amino and cyano) was developed and evaluated as an extraction device for in-tube SPME. The morphological and structural aspects of the monolithic phase were evaluated by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), nitrogen sorption experiments, X-ray diffraction (XRD) analyses, and adsorption experiments. In-tube SPME-MS/MS conditions were established to remove matrix, enrich analytes (monolithic capillary) and improve the sensitivity of the MS/MS system. The proposed method was linear from 45 to 360 ng mL−1 for alanine, from 15 to 300 ng mL−1 for leucine and isoleucine, from 12 to 102 ng mL−1 for methionine, from 10 to 102 ng mL−1 for tyrosine, from 9 to 96 ng mL−1 for tryptophan, from 12 to 210 ng mL−1 for serine, from 12 to 90 ng mL−1 for glutamic acid, from 12 to 102 ng mL−1 for lysine, and from 6 to 36 ng mL−1 for aspartic acid. The precision of intra-assays and inter-assays presented CV values ranged from 1.6% to 14.0%. The accuracy of intra-assays and inter-assays presented RSE values from −11.0% to 13.8%, with the exception of the lower limit of quantification (LLOQ) values. The in-tube SPME-MS/MS method was successfully applied to determine the target AA and NT in plasma samples from schizophrenic patients. View Full-Text
Keywords: in-tube SPME-MS/MS; dual ligand organic-silica hybrid monolith capillary; amino acids; plasma samples in-tube SPME-MS/MS; dual ligand organic-silica hybrid monolith capillary; amino acids; plasma samples
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MDPI and ACS Style

Miranda, L.F.C.; Gonçalves, R.R.; C. Queiroz, M.E. A Dual Ligand Sol–Gel Organic-Silica Hybrid Monolithic Capillary for In-Tube SPME-MS/MS to Determine Amino Acids in Plasma Samples. Molecules 2019, 24, 1658.

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