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Current Advancements of Serotonin Analysis in Plants
Published in Akula Ramakrishna, Victoria V. Roshchina, Neurotransmitters in Plants, 2018
Soumya Mukherjee, Akula Ramakrishna
Higher range of serotonin detection limits and characterization of its derivatives has been better obtained by liquid chromatography coupled to tandem mass spectrometry. Methanolic extracts have been reported to be obtained by Cao et al. (2006). Separation was obtained by gradient of 0.45% formic acid: acetonitrile (95:5% (v/v); 5–6 min), followed by 95:5% to 0:100% (v/v) for 6–16 min and 0:100% (v/v) for 6 min. Elution of serotonin was obtained at 16 min at a flow rate of 0.25 mL/min. Serotonin was detected and quantified through electrospray ionization (ESI), atmospheric pressure chemical ionization (APCI), and atmospheric pressure photoionization (APPI) modes respectively. Ion transition of parent molecule 177 u was monitored to the principle daughter ion 160 u in ESI, as well as 178–161 u in APCI and APPI. Inclusion of 0.45% formic acid in the solvent gradient has been reported to be suitable for separation and analyte ionization. The method of detection of serotonin by Cao et al. (2006) involves limit of detection and limit of quantification for serotonin to be 100 pg/mL and 5 ng/mL, respectively. Direct infusion of HPLC fractions into mass spectrometer and analysis of serotonin by ESI-MS method have been reported by Ramakrishna et al. (2012a).
Metabolomic Techniques to Discover Food Biomarkers
Published in Dale A. Schoeller, Margriet S. Westerterp-Plantenga, Advances in the Assessment of Dietary Intake, 2017
Pekka Keski-Rahkonen, Joseph A. Rothwell, Augustin Scalbert
Interfacing of the LC system to MS is made through an ion source, which is used to evaporate the sample and ionize the dissolved molecules for their detection as ions. Different ion sources are available which will cause major differences in metabolite coverage. Most published metabolomics methods have been based on electrospray ionization (ESI), which is most suitable for the analysis of compounds that are ionizable in solution. ESI is a soft ionization technique that does not induce excessive fragmentation of chemically labile compounds, but is somewhat susceptible to coeluting matrix interferences from the biological background. Matrix effects, such as ion suppression, can mask the concentration–response relationship or render a compound undetectable. Alternative ion sources such as atmospheric pressure chemical ionization (APCI) and atmospheric pressure photoionization (APPI) are available, which both enable more efficient ionization of neutral compounds and suffer less from matrix effects, although with less efficient ionization of highly polar metabolites and more in-source fragmentation. The potential benefits of APCI and APPI in metabolomics have been well recognized, but they have remained less commonly used (Ernst et al. 2014; Mirnaghi and Caudy 2014). Irrespective of the ion source type, an important parameter is the ionization mode used to create the ions. Depending on the molecular structure, it may be possible to detect a metabolite only as a cation or an anion, and it is thus advantageous to perform sample analyses with both polarities. In addition to ion sources, a promising new technology for LC–MS metabolomics is ion mobility MS. This is achieved with a hybrid instrument where the ions generated in the ion source are taken into a gas-phase separation system before mass analysis. This enables measuring the drift time for the ions, which is analogous to LC retention time, and can add another dimension to the data that can increase the number of selectively detected compounds (Dwivedi et al. 2010; May et al. 2015). One challenge of the technique lies in the processing of the acquired data, which require software that can fully exploit the additional drift time measurements.
A sensitive and high-throughput LC-ESI-MS/MS method to detect budesonide in human plasma: application to an evaluation of pharmacokinetics of budesonide intranasal formulations with and without charcoal-block in healthy volunteers
Published in Drug Development and Industrial Pharmacy, 2021
Xin Li, Huan Tong, Bing Xu, Yang Deng, Yuan Li, Junchen Huang, Yong Mao, Mengqin Liu, Ping Zhang, Siwei Guo
LC-MS/MS is the most used method for detecting budesonide. It is obvious that a low level of matrix suppression about 10–30% consistently exists when using the ESI source [17,21]. This may be caused by the co-elution of endogenous substances such as phospholipids and cholesterol. Even though Nilsson et al. [22] tried to use a phospholipid removal plate to remove most of the phospholipids, they still observed ion suppression, resulting in a low recovery. The atmospheric pressure chemical ionization (APCI) or atmospheric pressure photoionization (APPI) source seems to slightly less liable to MF than ESI source. [19,24] In addition, the application of co-eluting isotopically labeled IS could be an effective alternative strategy to offset the suppression of matrix. [19] In our study, nearly 20% matrix suppression was observed, which was consistent at different plasma levels. When normalized by isotopically labeled IS, the MF, as measured by their CV (%), was lower than 4.1%.
Bioanalytical strategies in drug discovery and development
Published in Drug Metabolism Reviews, 2021
Aarzoo Thakur, Zhiyuan Tan, Tsubasa Kameyama, Eman El-Khateeb, Shakti Nagpal, Stephanie Malone, Rohitash Jamwal, Chukwunonso K. Nwabufo
PPT is another simple, non-selective sample preparation method for the removal of proteins from biological matrices before analysis. It is analogous to the dilution method but is generally used for high protein matrices that include plasma, serum, whole blood, and cell lysate (Bylda et al. 2014). In principle, the addition of solvents, acids, bases, and salts stimulates PPT in a biological matrix. This technique involves the use of strong organic solvents (acetonitrile, methanol) to precipitate proteins followed by centrifugation to sediment the insoluble proteins. The supernatant is further utilized for downstream processing or injection. It is widely adopted for the analysis of drugs in plasma, serum, and other biological matrices (Jamwal et al. 2017; Adusumalli et al. 2019). Although PPT is relatively quick and easy, one of the major drawbacks of this non-selective method is the inefficient removal of phospholipids (PLs) and other soluble protein interference leading to matrix effects and variability in sample analysis (Bylda et al. 2014). PLs are an integral part of all cell membranes and therefore are present in all biological matrices. The presence of co-eluting PLs in the sample is problematic in LC-MS analysis because they are often co-elute and suppress the ionization of analytes of interest (Khoury et al. 2016). Matrix effects are significantly more troublesome and prominent when using electrospray ionization (ESI) than other modes (e.g. atmospheric pressure chemical ionization, APCI and atmospheric pressure photoionization, APPI) (King et al. 2000). In general, acetonitrile is much more effective for the removal of PLs from common biological matrices than methanol (Chambers et al. 2007; Alzweiri et al. 2008; Michopoulos et al. 2011). Polson and colleagues published on optimization of PPT for effective removal of plasma proteins and ionization effect in LC-MS/MS (Polson et al. 2003). The authors suggested the use of trichloroacetic acid (TCA) and mobile phases containing pure organic solvents (methanol: water or acetonitrile: water) for the optimal removal of plasma proteins.