Mass spectrometry (MS) is a technique used to analyze the mass-to-charge ratio of ions present in a sample. This technique allows for identifying and quantifying unknown compounds such as small molecules, proteins, and lipids in various samples. The analytical method is carried out on an ms bench and works by ionizing the sample into gas-phase ions. Here are the general steps involved in performing mass spectrometry:
Sample Preparation
The preliminary step of the sample preparation step aims to clean up and concentrate the sample to increase sensitivity, reduce the interference effects, and achieve accurate results. It involves selecting the appropriate sample preparation method, such as extraction, digestion, or derivatization. The best method depends on the MS bench, the sample’s type, size, and complexity. A wrong or inadequate sampling technique may contaminate the sample and affect the mass spectrometry results.
Ionization
Once the sample is prepared, the mass spectrometer converts it into gaseous ions, which are separated based on their mass-to-charge ratio (m/z). Ionization aims to produce as many ions as possible from sample molecules. The most commonly used ionization techniques in mass spectrometry include electrospray ionization (ESI), chemical ionization (CI), and matrix-assisted laser desorption/ionization (MALDI). The selection of the ionization technique depends mainly on the sample’s nature, the technique’s ionization efficiency, and the required sensitivity of the analysis.
Mass Analysis
The mass analysis separates the ions based on their mass-to-charge ratios (m/z), forming an ion spectrum. This analysis involves subjecting the ionized sample to an electric or magnetic field, which separates the ions based on their m/z. The mass spectrum produced gives information about the sample’s molecular weight and chemical structure.
The most common mass analyzers used in mass spectrometry include:
Time-of-flight (TOF) Mass Analyzer
Time-of-flight (TOF) mass analyzers are widely used for many mass spectrometry applications. It measures ions’ time of flight, from the ion source to the detector, in an electric field. It is proportional to the ion mass-to-charge ratio. With high mass accuracy, high resolution, and a full mass range, TOF analyzers are suitable for analyzing large biomolecules, peptides, and proteins.
Quadrupole Mass Analyzer
The Quadrupole Mass Analyzer is another commonly used analyzer in many mass spectrometry applications. This analyzer separates ions according to their mass-to-charge ratio. A quadrupole mass analyzer consists of four parallel metal rods that create a radio-frequency (RF) field where the ions are trapped and separated. Quadrupole mass analyzers have many advantages, including mass range flexibility, rapid data acquisition, and affordability.
Ion Trap Mass Analyzer
This is another widely used analyzer in mass spectrometry. It captures ions in a 3D trap made by applying electrical and magnetic fields. Ions are confined to space between two endcaps, and a central ring electrode creates an RF voltage to trap the ions. The ion trap mass analyzer’s advantages include its high resolving power, low sample requirement, high sensitivity, and the ability to analyze labile or fragile biomolecules
Detection
In this step, the separated ions are detected and quantified. This step helps in the analysis of chemical samples since the separation process can produce a large number of ions. The detector, for this purpose, converts the ions into electrical currents, which are then interpreted to create a spectrum. Different detectors, such as electron multipliers, photomultipliers, or Faraday cups, can be used.
Data Analysis
In this step, the raw data generated by the mass spectrometer is processed and analyzed using specialized software. Data analysis is key for interpreting and validating the results. Lab managers should confirm that their team has the necessary skills and training to accurately perform data analysis and interpretation.
Use a Quality MS Bench While Performing Mass Spectrometry
MS lab bench is used to analyze the mass-to-charge ratio of ions in a sample during the mass spectrometry process. The bench enables lab experts to handle and analyze samples more efficiently, making them valuable tools. By choosing the right lab bench, laboratories can optimize workflow efficiency, increase productivity, and achieve better research results.
