Reverse micellar microextraction for rapid analysis of thiol‐containing peptides and amino acids by atmospheric‐pressure matrix‐assisted laser desorption/ionization ion trap and matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry

Abstract

Simple, rapid and inexpensive one-step reverse micellar microextraction (RMME) procedures were combined with matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS) for the determination of thiol-containing peptides and amino acids. In this investigation, a thiol-containing peptide (HW6) was chosen as model compound to understand the mechanism of RMME. The electrostatic interactions between the thiol-containing peptide and reverse micelles were proposed to be reason for the transfer of analytes from the aqueous phase to the organic phase. Reverse micelles were formed by the cationic surfactant, methyltrioctylammonium chloride (MTOAC). The best extraction efficiency of HW6 was obtained under the following conditions: pH 11.0, ionic strength 5.0 mM of KCl and micelle concentration 7.0 mM of MTOAC. The limits of detection (LODs) obtained for HW6 in water, urine and plasma samples were 0.15, 0.19 and 0.28 microM, respectively, with relative standard deviation (RSD) values in the range +/-8.8-10.5%. The sensitivity obtained in water by the present method was 45-fold higher than that of the conventional use of atmospheric-pressure (AP)-MALDI MS. Furthermore, the applicability of the proposed approach was extended for the determination of thiol-containing amino acids in sample solutions by using MALDI time-of-flight (TOF) MS.

Applications of silver nanoparticles capped with different functional groups as the matrix and affinity probes in surface‐assisted laser desorption/ionization time‐of‐flight and atmospheric pressure matrix‐assisted laser desorption/ionization ion trap mass spectrometry for rapid analysis of sulfur drugs and biothiols in human urine

“…The potentiality of the present method was compared with other existing methods35, 58–61 for the determination of biothiols (cysteine, homocysteine and thiopeptides) in SALDI‐TOF MS or AP‐MALDI‐ITMS and it was found to be better than these methods in respect to simplicity, rapidity and sensitivity for analysis of aqueous solutions or biological samples. The reason for the higher sensitivity of the present method is due to the fact that the high surface area and excellent photochemical property of AgNPs can enhance the detection signals of biothiols.…”

Determination of glutathione and glutathione disulfide in biological samples: An in-depth review

“…Novel techniques to enhance the separation and measurement of thiols with MS include the adsorption of positively charged peptides on the surface of negatively charged bare (uncapped) silica nanoparticles [97], and a one-step reverse micellar microextraction (RMME) procedure for the determination of thiol-containing peptides and AAs [98]. Reverse micelles were formed by the cationic surfactant methyltrioctylammonium chloride [98].…”

“…Novel techniques to enhance the separation and measurement of thiols with MS include the adsorption of positively charged peptides on the surface of negatively charged bare (uncapped) silica nanoparticles [97], and a one-step reverse micellar microextraction (RMME) procedure for the determination of thiol-containing peptides and AAs [98]. Reverse micelles were formed by the cationic surfactant methyltrioctylammonium chloride [98]. Omitting the derivatization step greatly simplifies the sample preparation process and increases the sample throughput [99], but can result in excessive autoxidation and consequently erroneous results (detailed in Section 2.1).…”

Matrix-assisted laser desorption/ionization mass spectrometry for quantitative determination of β-blocker drugs in one-drop of human serum sample

“…Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) is a rapid and powerful technique for the analysis of biomolecules, including peptides, proteins and nucleic acids [11][12][13][14][15][16]. Recently, MALDI-MS has been applied for the monitoring of drugs and environmental toxicants due to its high sample throughput and easy operations [17][18][19][20].…”

“…Sample preparation in MALDI-MS is the most important step for obtaining a good quality spectrum, which could be helpful for easy identification of particular target compounds in complex samples. Several sample preparation methods are regularly practiced for the MALDI-MS analysis of drugs, proteins, and pollutants from complex matrices samples [13][14][15][16][17][18][19][20]. The most widely used techniques for the separation and preconcentration of trace amount of analytes include, liquid-liquid extraction (LLE) [21] and solid-phase extraction (SPE) [22].…”