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Miscellaneous Methods of Analysis
Published in Joseph Chamberlain, The Analysis of Drugs in Biological Fluids, 2018
Flow injection analysis is an analytical technique which emerged in the early 1970s and has attracted much theoretical and practical development, particularly in pharmaceutical analysis where there is a demand for the monitoring of materials and where the demands of sensitivity and specificity are not great, such as analysis of caffeine,1299 corticosteroids,1300, and codeine1301 in tablets. The term was apparently coined by Ruzicka and Hansen,1302 who, with Stewart,1303 were responsible for much of the early development. Stewart’s review of the principles of the technique had the revealing subtitle “New tool for old assays.” This gives a good indication of the origins and applicability of the methods, that is, flow injection analysis draws on the well-established methods of chemical analysis, but uses the new tool to automate and miniaturize them for the more up-to-date requirements of speed and quantity. Recently, Ruzicka1304 has reviewed the history and development of the technique and shown that with the addition of modern computer-controlled procedures, the technique has undreamed of potential.
Cyanides: Toxicology, Clinical Presentation, and Medical Management
Published in Brian J. Lukey, James A. Romano, Salem Harry, Chemical Warfare Agents, 2019
Gary A. Rockwood, Gennady E. Platoff Jr., Harry Salem
The ECG may show increased T-wave amplitude, shortening of the S-T segment, third-degree heart block, supraventricular or ventricular tachycardias, A-V block, and ischemic myocardial changes (Ballantyne et al., 2006; DeBush and Seidel, 1969; Lee-Jones et al., 1970). Plain chest radiography may demonstrate pulmonary edema. Lactate acidosis is an important biochemical feature of acute CN intoxication and if marked, is accompanied by an elevated anion gap (Baud et al., 1991; Graham et al., 1977; LaPostolle et al., 2006; Peddy et al., 2006). The AKBR (acetoacetate/β-hydroxybutyrate), which reflects the redox state of hepatic mitochondria, is a useful measure for the progress of treatment of CN poisoning (Nakatani et al., 1993). Arterial blood O2 analysis and A-V O2 differences often demonstrate high arterial blood PO2, increased venous blood PO2, and reduced A-V O2 difference. Although most clinical pathology laboratories do not have the capability to undertake rapid quantitative analysis for CN, blood samples should be collected into tightly closed tubes for subsequent analysis. Blood should be collected as soon as possible after intoxication and analyzed promptly to reduce potential artifacts (Ballantyne, 1975, 1976, 1987b; Kulig and Ballantyne, 1993). The confirmation and analysis of CN, CN analogs, thiocyanate, ATCA, and CN–protein adducts in biological matrices and tissues is a valuable tool for forensic, clinical, research, law enforcement, and veterinary purposes (Logue et al., 2010). Methods of analysis include spectrophotometry, fluorescence, chemiluminescence, electrochemistry, gas chromatography (GC), liquid chromatography (LC), flow injection analysis (FIA), capillary electrophoresis (CE), and atomic absorption (AA). There are many factors that influence the choice of which biomarker and/or analytical technique should be used. Considerations include cellular absorption and detoxification kinetics, sampling and analysis time, sample storage time and conditions, sample matrix, interferences, sensitivity, available instrumentation and equipment, expertise, and cost. Careful sample preparation and storage of biological samples containing CN or its metabolites is a key element in producing accurate results. A significant problem in the analysis of CN and thiocyanate is their interconversion, which can occur during sample preparation and storage and can lead to inaccurate results. Thus, methods have been developed to prevent artificial formation of CN during the storage of collected samples. Recent strides to develop accurate, rapid, and cost-efficient methodologies and technologies have recently been summarized by Jackson and Logue (2017).
Characterization of metabolites of larotaxel in rat by liquid chromatography coupled with Q exactive high-resolution benchtop quadrupole orbitrap mass spectrometer
Published in Xenobiotica, 2018
Zhenzhen Liu, Pengyi Hou, Lian Liu, Feng Qian
The MS/MS fragmentation pattern of larotaxel was studied in order to facilitate a better understanding of the MS/MS spectra of its metabolites. Mass spectrometric parameters were optimized in both positive and negative ionization modes with infusion and flow injection analysis. Ionization of parent larotaxel was much better in the positive ionization mode than in the negative mode, and signal intensity for [M + Na]+ ion was thirty- to forty-fold higher than that for [M + H]+ ion. The product ions of [M + Na]+ and proposed fragmentation scheme for larotaxel are shown in Figure 2. The parent ion of larotaxel was sodium adduct ion at m/z 854.33606 ([M + Na]+) in the positive ionization mode. In the MS/MS spectrum, it had characteristic product ions at m/z 573.20929, 513.18829, 304.11533, 248.05276, 204.06302 and 105.03354 (Table 2). These spectra were considered to be formed by cleavage of the C-13 side chain and further sequential loss of CH3COOH, C6H5COOH, H2O, C4H8 or CO2, and the predicted fragmentation pattern of larotaxel was also shown in Figure 2. These characteristic ions of the parent drug are used to interpret the mass spectra of metabolites.
Serum and plasma amino acids as markers of prediabetes, insulin resistance, and incident diabetes
Published in Critical Reviews in Clinical Laboratory Sciences, 2018
C. Gar, M. Rottenkolber, C. Prehn, J. Adamski, J. Seissler, A. Lechner
An alternative to chromatography, mass spectrometry (MS) can also directly separate most amino acids (separation of metabolites with different molecular weights or different fragmentation patterns) [60]. This method is often combined with direct sample injection, e.g. the widely used flow injection analysis (FIA). Even if the direct injection lowers the ionization efficiency, this combination analyzes rapidly and covers a wide range of metabolites with high selectivity and a very low limit of detection [51,61]. One disadvantage of direct MS for metabolite separation is the need for a sample preparation, which probably causes a loss of metabolites by a reaction with added substrates or a degradation when physical conditions are changed [62]. Additionally, ionization effects impair the quantification of compounds [51,62,63]. Hence, MS is primarily used for detection in combination with other separation methods.
Automated approach for the evaluation of glutathione-S-transferase P1-1 inhibition by organometallic anticancer compounds
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2022
Sarah A. P. Pereira, A. Catarina Baptista L, Lorenzo Biancalana, Fabio Marchetti, Paul J. Dyson, M. Lúcia M. F. S. Saraiva
Several GST inhibition batch assays have been reported resorting to a different mode of detection, such as an electrochemical assay using a glassy carbon electrode with differential pulse voltammetry to evaluate GST kinetic parameters8, or an immunocytochemistry technique to evaluate the cellular reactivity of GSTπ9. With a higher level of mechanisation, a high-resolution screening (HRS) technique using two simultaneous enzyme affinity detection (EAD) systems for human GST P1-1 using reverse-phase high-performance liquid chromatography (HPLC). This system was first optimised and validated using a flow injection analysis (FIA) system and the optimised results were then used in HPLC mode10.