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Emerging Biomedical Analysis
Published in Lawrence S. Chan, William C. Tang, Engineering-Medicine, 2019
Many variants of ESI have been developed in recent years. Ambient ionization is a family of techniques that was derived from ESI to enable rapid MS analysis at lower cost. Ambient ionization techniques generate ions under ambient conditions for subsequent MS analysis directly on the sample with minimum sample preparation (Cooks et al. 2006, Nyadong et al. 2007). Representative ambient ionization techniques are desorption electrospray ionization (DESI) and direct analysis in real time (DART). In the DESI technique, an electrospray of charged solvent droplets hits the sample surface and extracts analyte molecules to form secondary droplets (Fig. 2). The secondary droplets undergo a similar ionization process with ESI and eventually are delivered to the inlet of a mass spectrometer (Takats et al. 2004). In the DART methodology, an electrical potential is applied to a helium gas stream to generate metastable species. These excited-state gas molecules subsequently react with the analyte surface to form ions (Cody et al. 2005). Due to the simple and cost-effective experimental setup, DESI, DART and other ambient ionization techniques, such as paper spray ionization, liquid microjunction surface sampling probe (LMJ-SSP) and rapid evaporative ionization mass spectrometry (REIMS), were used in several clinical studies (Li et al. 2017). Examples of clinical applications of ambient ionization MS will be discussed later in this chapter.
Basics Of Gas Chromatography Mass Spectrometry System
Published in Raquel Cumeras, Xavier Correig, Volatile organic compound analysis in biomedical diagnosis applications, 2018
William Hon Kit Cheung, Raquel Cumeras
There are multiple names given for this analytical technique, Direct Analysis in Real Time (DART) (Beckman, 2008; Fuhrer, 2011) or Direct Injection Mass spectrometry (DIMS), but the principle is the same; the sample is introduced into the MS system through the use of electrospray ionization interface without any form of chromatographic separation applied, and the entire mass spectrum of the sample is measured and recorded. This is a high-throughput low-level chemical information fingerprinting approach; since no chromatographic separation is applied the complexity of the mixture is not reduced. In DART/DIMS analysis, the effect of ion suppression is significant since the entire sample is being ionized at the same time. If the sample matrix is complex in nature, low abundance ions would likely to be missed due to heterogeneous ionization effect.
Positional scanning of natural product hispidol’s ring-B: discovery of highly selective human monoamine oxidase-B inhibitor analogues downregulating neuroinflammation for management of neurodegenerative diseases
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2022
Ahmed H. E. Hassan, Hyeon Jeong Kim, Min Sung Gee, Jong-Hyun Park, Hye Rim Jeon, Cheol Jung Lee, Yeonwoo Choi, Suyeon Moon, Danbi Lee, Jong Kil Lee, Ki Duk Park, Yong Sup Lee
General: All solvents and reagents have been purchased from commercial suppliers and used without any further purification. NMR spectra were acquired on Bruker Avance 400 spectrometer (400 MHz) or JEOL JNM-ECZ500R spectrometer (500 MHz). 1H NMR spectra were referenced to tetramethylsilane (δ = 0.00 ppm) as an internal standard. High-resolution mass spectra (HRMS) were recorded on Jeol AccuTOF (JMS-T100TD) equipped with a DART (direct analysis in real time) ion source from ionsense, Tokyo, Japan in the positive modes. TLC was carried out using glass sheets pre-coated with silica gel 60F254 purchased by Merk and spots were visualised under UV lamp or using staining solutions, such as p-anisaldehyde solution, ninhydrin solution. 6-Methoxy-3-coumaranone and compounds 1a, 1b, 1d, 1e, 1f, 1h–1t, and v–1y were in agreement with reported literature (Supplementary materials)43,49,53–58.
Novel methods in glycomics: a 2019 update
Published in Expert Review of Proteomics, 2020
Wei-Qian Cao, Ming-Qi Liu, Si-Yuan Kong, Meng-Xi Wu, Zheng-Ze Huang, Peng-Yuan Yang
Mass spectrometry-based imaging (MSI) techniques, mainly including secondary ion mass spectrometry (SIMS), MALDI-MS, desorption electrospray ionization mass spectrometry (DESIMS), and direct analysis in real-time mass spectrometry (DARTMS), have been widely used and applied to a variety of biomolecules [16,167,168]. MALDI-imaging mass spectrometry (IMS) is an emerging tool for analyzing the spatial distributions of glycans. The classical workflow involves the on-tissue release of glycans, followed by spraying matrix and MALDI-IMS analysis. To date, many types of tissue samples, including frozen tissues, formalin-fixed paraffin embedded (FFPE) tissues, and tissue microarrays, can be used for MALDI-IMS analysis [169–172]. With this method, in addition to mapping the relative distributions of different glycans in different tissue areas [170,173–175], glycans with different linkages, such as α-2,6 sialic acids and α-2,3 sialic acids, can also be differentially imaged [169]. MALDI-IMS is undeniably a powerful technique for the spatial analysis of glycans in organisms. Studies on bioinformatics tools for imaging data processing, repositories for imaging data storage and references, and methods for more detailed glycan structural identification on tissues are still in continuous development.
The interpretation of hair analysis for drugs and drug metabolites
Published in Clinical Toxicology, 2018
Eva Cuypers, Robert J. Flanagan
One issue in using MALDI-MS of intact hair strands is the extraction efficiency of the procedure. As drugs are thought to be trapped inside the matrix (core) of the hair as the hair is formed in the hair follicle, it is difficult to know if the drug is completely extracted out of the hair by the MALDI procedure and if the detected drug originates from either surface contamination, or from within the hair itself. Duvivier et al. [63] used direct analysis in real time (DART) ambient ionization orbitrap MS to detect tetrahydrocannabinol in an entire lock of hair without prior decontamination. Hairs were attached to stainless steel mesh screens and immediately scanned. However, hairs were scanned before and after washing with dichloromethane in an attempt to remove surface contamination hence the possibility of interference from this source remained.