The Use of Liquid Chromatography-Tandem Mass Spectrometry in Metabolomics - Essay Example

Essay on the use of LC-MS/MS in metabolomics including fundamentals of LC-MS/MS Name Course Date Introduction The application of Liquid chromatography/tandem mass spectrometry (LC-MS/MS) technique in the study of metabolomics is a recent development, but LC-MS has been used in clinical biomarkers detection [1]. Metabolomics study involves quantitative or qualitative analysis of metabolites that include low molecular weight compounds like carboxylic acids, amino acids, biogenic amines etc. in a sample [1]. LC-MS/MS has become an important tool the analysis of metabolites due to the polar nature of metabolites [1]. Metabolomics study has becomes an integral part biochemistry assessment, drugs safety analysis, nutrition and microbiology to give more insight into molecular network. In clinical applications, metabolome study is used to detect new biomarkers that related to health. In addition, quantitative analysis helps in the understanding of the pathophysiology and assessment of the individual risk of complex diseases like cancer, heart disease and diabetes [2]. In new development LC-MS/MS has been used to screen inherited diseases for newborns. This method combines liquid chromatography with tandem mass spectrometry techniques [3]. Mass spectrometer is a powerful MS analyzer technology which was developed in 1990s. It has ion source, analyzer and detector, and can generate mass spectra which provide masses for the analyte. It has a wide range of data read out used in routine laboratory medicine [1][4]. MS/MS use two stages of mass analysis. The first one is preselecting an ion and the second one is to analyze collision induced fragments of ion using an inert gas like helium or argon. On the other hand, when LC is coupled with MS/MS in LC-MS/MS system, is can separate analyte from matrix signal as well as analytes from coelute, therefore enabling quantification of sample traces in a complex matrices [5]. This essay gives analytical review and discusses the application of LC-MS/MS technique in metabolome analysis and human body fluid clinical research. Instrumentation LC-MS/MS consist of Liquid Chromatography system joined to mass spectrometer. Liquid chromatography enables the separation on an analytical column and mass spectrometer instrument enables ions formation and detection. Various compounds can be resolved in LC depending on the type of column and the set up plus the characteristics of the pump. Mass spectrometers instrument is divided into three parts, which include: ionisation source, analyser, and detector [1]. Ionisation The samples are first ionized in the ionization source, before being separated in the analyzer depending on their mass to charge ratio (m/z). The ions are detected as data signal where they presented in form of m/z spectrum. The ionization methods include: Chemical Ionisation (CI), Electron Impact (EI), Atmospheric Pressure Chemical Ionisation (APCI), Electrospray Ionisation (ESI), and Matrix Assisted Laser Desorption Ionisation (MALDI). ESI and MALDI are the most commonly used methods in biochemical analyses [1] [6]. Analyzer The mass analyzer resolves the ions formed in ionization chamber depending on their m/z ratios. The mass analyzers used include: time-of-flight (TOF), quadrupoles, quadrupole ion traps, magnetic sectors and Fourier transform analyzers. Tandem mass spectrometry uses more than one analyzer. The most preferred mass spectrometer which allows MS/MS experiments are quadrupole ion trap (QIT) and triple quadrupole (TQ) [1][7]. This is because they are easy to operate, robust in daily analysis, and low cost. TQ is widely used because it is small in size, easy to handle and has low cost. Mass separation is based on ions specific values m/z in an electrostatic field. Ions are usually accelerated through parallel hyperbolic rods. The ions then move from the applied field through the filter to the detector. QIT analyzer operates like quadrupole instrument except the fact that it has three only three electrodes: one ring electrode sandwiched between two hyperpolic electrodes. One of the limitations of QIT is its limited dynamic range. It also has limited data acquisition compared to TQ [5]. The advantages of QIT mass analyzer are its small size, automated and easy to use, sensitive, versatile and fast and can perform multiple stages of MS as well as store negative and positive ions for a long time. But it has low resolutuion, small dynamic space and can be interfered by side reactions. Hybrid quadrupole-TOF (Q-TOF) mass analyzer is the simplest fastest. The samples ions are accelerated with same energy, but they separate from one another and reach the detector different times. Its advantages include: its high degree of sensitivity, large mass range, and simultaneous detection of ions of all masses [1] [7]. Detection The monitor detects the ion current signal and amplifies it before being recorded in data system in form of mass spectra. The ions’ m/z values will show the number of components in the sample, their molecular mass and their relative abundance. The most common detectors are microchannel detector, electron multiplier and photo-multiplier. The signal produced in the detector in the course of the scan generates a mass spectrum, which is a record of ions as a function in the form m/z [1] [7]. Advantages LC-MS/MS is more preferred due to different reasons. The first one is that it has high analytical specificity and accuracy. This is because the MS/MS analysis reduces chemical noise, hence providing unbiased and accurate results [7]. It also easy to use and has a wide range of applicability with a considerable number of analytes, and with good practicability as compared to other techniques, which also include its use in volatile liquid [8]. In addition, it is easy to prepare a sample as it is not necessary to use derivatization techniques. This technique can also enable the detected assays to be optimized to shorter runtimes increasing sample throughput and it can be developed with high flexibility within a short time. It is also preferred for quantitating metabolites, small molecule drugs biological matrix xenobiotic biomolecules such as urine, blood, tissue, serum and plasma. Finally, a large number of qualitative and quantitative information can be obtained from one LC-MS/MS run [1] [8]. Disadvantages Despite the above advantages, LC-MS/MS has limitations. Analysis by use of LC-MS/MS technique not only requires a trained operator to analyze and maintain the system, but it also require high capital to purchase the instruments [1]. Its chromatography efficiency is less compared to GC-MS; it has susceptibility to matrix effects and also inter-instruments variability in fragmentation pattern. In addition, cannot detect some analyte groups like steroid hormone and cytokines with blood in lower molecular range [9]. Applications of LC-MS/MS Different analytical standards are applied in metabolome analysis owing to different chemical structures. Therefore, different extraction techniques are used. The metabolites analysis can be conducted in two ways. These include targeted analysis: unbiased assessment used in sample pretreatment; and targeted analysis: analysis of predetermined, specific metabolites. LC-MS/MS has been applied in quantitative analysis of a various analytes of physiological matrices, and can detect a wide range of compounds with great specificity and sensitivity. Thus, it is used to solve a majority of the analytical problems [10]. In the analysis of complex metabolites like trace of drugs concentration, analyzes is required in a biomatrix. The measurement of change in relative concentration in known metabolites can be determined by analyzing using the system and comparing the signals obtained for different metabolites [9]. The main use of LC-MS/MS in lipdiomics is the clinical laboratories application. It is applied in the identification of lipids species like bile acids and steroids. However, most the applications occur in the biomarker research [1] [9]. In laboratory studies of metabolism, the technique is used to study drug metabolism, biochemical toxicology and pharmacokinetics. In this study, metabolites are detected, but also the characteristics of the structure and quantitative analysis. This analysis is carried out using triple-quadrupole mass spectrometers as it provides high specificity and sensitivity of the metabolites [1] [11]. It is also used diagnosis of aberrations in endocrine system such as quantification for biogenic amines, steroids, steroids, thyroid hormones, amino acids and vitamin D. In addition, it enables the use of sophisticated metabolites pretreatment methods and automation of the process through online coupling of separation technique. This has resulted in improvement of biochemical diagnosis of endocrine disorders as well as open new way to gain knowledge of pathophysiological processes [13]. LC–MS/MS has been applied in the identification of cancer cell metabolic fingerprint. In particular, metabolomic studies were conducted for cancer types such as breast, kidney, prostrate and ovarian cancer [14] The polar nature of amino acids, its analysis is done with derivatisation using reversed chromatography together with mass spectrometry. Due to its ability to measure several compounds simultaneously, with superior specificity simple sampling preparation and short runtime, LC-MS/MS has been the main tool for quantification for low molecular weight biomarker in clinical chemistry. It is preferred because of it has overcome the limitation of the conventional methods like long analysis time and possibility of interference [13, 14]. It overcomes drawbacks of conventional techniques, such as long analysis times and chance of interferences, has a broad analyte compatibility and high analytical performance [8]. It is also used in screening of body fluid such as during drug testing in sports. It has capabilities to complement the conventional immunological detection techniques for prohibited compounds. It is applied in anti-doping laboratories for testing and confirmation of the prohibited compounds [9]. Using high accuracy and resolution MS, it offers sensitive and fast analysis of targeted as well as untargeted screening. The preselected target analytes are measured in low resolution tandem mass spectrometers using diagnostic precursor production pairs, before extracting ion chromatograms of deprotonated or protonated molecules. LC-MS/MS has been used in sports drug testing for over 10 years, and the instruments has been improved through expansion of the supportive features. This has enhanced the speed and quality of doping analysis for high and low molecular weight compounds [9, 13]. It is also used in monitoring therapeutic drugs for immunosuppressant because of its specificity and sensitivity, in the care of post-transplantation patients. Typically, LC-MS/MS is run for a short time while monitoring the immunosuppressant. The only limitation is that the system requires a very large capital to install as well as trained personnel to operate and maintain it [15]. In the diagnostics of inherited diseases, amino acids are screened so as to detect inborn errors in fatty acids and amino acids. LC-MS/MS has also been used successfully to test galactose metabolizing enzymes. The method complements the radioactive approach, and also eliminates the enzyme coupled reaction. It provides more conclusive results because if low activity is detected, it can be due to deficiency of the some enzymes. In addition, Hexose monophosphates are determined in dried blood. Newborns are also screened for maple syrup urine disease including quantification of hydroxyproline [16]. Conclusion LC-MS/MS is evidently a powerful analytical tool for determination and quantification of metabolites samples in biochemistry. It utilizes electrospray ionization and operates in a multiple reaction mode. It is used in both targeted and non targeted quantification due to its sensitivity and selectivity. In addition, its capability to screen for identity and quantity of a varied range of metabolites in a single run has made it the most preferred technique. Simple extraction procedure has also enhanced the research study. Hence, the advancement in LC-MS/MS system has not only boosted the research, but it has also boosted the economy. With the recent development in software, this technique has been made easy to use. References [1] JU-SEOP KANG. (2012). Principles and Applications of LC-MS/MS for the Quantitative Bioanalysis of Analytes in Various Biological Samples. INTECH Open Access Publisher. http://www.intechopen.com/articles/show/title/principles-and-applications-of-lc-ms-ms-for-the-quantitative-bioanalysis-of-analytes-in-various-biol. [2] OLDFIELD, L. S. (2013). Application of liquid chromatography tandem mass spectrometry techniques to forensic, environmental and clinical analyses. Morgantown, W. Va, [West Virginia University Libraries]. http://hdl.handle.net/10450/14719. [3] LI, J, WANG, X, WANG, C, FU, Q, LIU, L, HUANG, M, & ZHOU, S. (n.d.). Rapid and simultaneous determination of tacrolimus (FK506) and diltiazem in human whole blood by liquid chromatography-tandem mass spectrometry: Application to a clinical drug-drug interaction study. Elsevier. http://researchbank.rmit.edu.au/view/rmit:2289. [4] MURRAY, G. I. (2011). Laser capture microdissection: methods and protocols. New York, Humana Press. [5 SOLER C, MAÑES J, & PICÓ Y. (2005). Comparison of liquid chromatography using triple quadrupole and quadrupole ion trap mass analyzers to determine pesticide residues in oranges. Journal of Chromatography. A. 1067, 1-2. [6] QUIGNOT, N., TOURNIER, M., POUECH, C., CREN-OLIVÂE, C., BAROUKI, R., & LEMAZURIER, E. (2012). Quantification of steroids and endocrine disrupting chemicals in rat ovaries by LC-MS/MS for reproductive toxicology assessment. Analytical and Bioanalytical Chemistry. 403, 1629-1640 [7] CORTÉS-FRANCISCO, N., FLORES, C., MOYANO, E., & CAIXACH GAMISANS, JOSEP. (2012). Accurate mass measurements and ultrahigh-resolution: Evaluation of different mass spectrometers for daily routine analysis of small molecules in negative electrospray ionization mode. Springer. http://hdl.handle.net/10261/60845. [8] PADUCH, D. A., BRANNIGAN, R. E., FUCHS, E. F., KIM, E. D., MARMAR, J. L., & SANDLOW, J. I. (2014). The Laboratory Diagnosis of Testosterone Deficiency. Urology. 83, 980-988. [9] GUILLARME, D., & VEUTHEY, J.-L. (2012). UHPLC in life sciences. Cambridge, U.K., Royal Society of Chemistry. http://search.ebscohost.com/login.aspx?direct=true&scope=site&db=nlebk&db=nlabk&AN=473927. [10] TZANAVARAS, P. D., & ZACHARIS, C. K. (2010). Reviews in pharmaceutical and biomedical analysis. [S.l.], Bentham e Books. http://public.eblib.com/EBLPublic/PublicView.do?ptiID=864262. [11] CRISP, T M, et al. (1998). Environmental endocrine disruption: an effects assessment and analysis. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1533291. [12] CLARKE W, RHEA JM, & MOLINARO R. (2013). Challenges in implementing clinical liquid chromatography-tandem mass spectrometry methods--the light at the end of the tunnel. Journal of Mass Spectrometry : JMS. 48, 755-67. [13] THEVIS, M., & SCHÄNZER, W. (2007). Current role of LC–MS(/MS) in doping control. Analytical and Bioanalytical Chemistry. 388, 1351-1358. [14] WANG, L., & MENG, M. (2013). LC-MS Bioanalysis of Nucleosides. 551-557. [15] Chris T. (2007). Abstracts for the 3rd International Congress on Stress Responses in Biology and Medicine and the 2nd International Congress of Stress Research, 2007. Cell Stress &Amp; Chaperones. 12, e1. [16] CARPENTER KH, & WILEY V. (2002). Application of tandem mass spectrometry to biochemical genetics and newborn screening. Clinica Chimica Acta; International Journal of Clinical Chemistry. 322, 1-2. Read More