Lc ms assay

Liquid Chromatography-Mass Spectrometry (LCMS): A Quick Guide For Beginners

The Liquid Chromatography-Mass Spectrometry (LC-MS) analytical is a hyphenated analytical technique that combines Liquid Chromatography (LC) with Mass Spectrometry (MS). HPLC (LC) separates mixture components by passing them through a chromatographic column. In general, LC alone cannot positively identify the separated members. Mass spectrometry is also used to identify new and recognized molecules and elucidate their structure. Because a mass spectrum mixture is essentially a complex of overlapping spectra from separated individual components, mass spectrometry alone is ineffective for detecting mixes. Liquid chromatography (LC) and mass spectrometry are challenging to link (MS). Lc ms assay is increasingly employed in drug solubility, bioavailability, bioequivalence, and pharmaceutical drug discovery.

The Liquid Chromatography-Mass Spectrometry (LC-MS) technique combines the separation capacity of HPLC with the detection power of Mass Spectrometry (MS). The components of an LC-MS instrument are given below.

a. Liquid Chromatography (LC)

b. Mass Spectrometry (MS)


Liquid Chromatography (HPLC): Liquid chromatography (LC) is a high-performance liquid chromatography technique that separates mixture components utilizing liquid mobile and solid stationary phases. HPLC components are a Pump, Sample injector, Columns, Detectors, and recorders.

Mass spectrometry: It is an analytical method that measures the mass to charge ratio of ionic species connected to the analyte under examination. Different components of Mass spectrometers are Ionization Sources, Interfaces, and Mass Analyzers.

Ionization/Ion Source and Interfaces: Liquid chromatography separates mixtures of liquid components, which often comprise methanol, acetonitrile, and water. This liquid-containing component combination is fed into the mass spectrometer’s ion source because the ion source is under a high vacuum. Because of the pressure differential, it is difficult to vaporize the liquid droplets without losing the combination of components. As a result, interfaces are utilized to tackle this problem. The many interfaces typically utilized in mass spectrometers are detailed here.

a. Direct liquid Introduction (DLI)

b. Atmospheric-Pressure Ionization (API)

c. Electrospray Ionization (ESI)

d. Atmospheric Pressure Chemical Ionization (APCI)

e. Thermo spray and Plasma spray Ionization (TSPI)

f. Atmospheric pressure photo Ionization (APPI)

g. Particle Beam Ionization

h. Continuous-Flow Fast Atom Bombardment (FAB)

Mass Analyzer: After ionization, the ions are sent to a mass analyzer, separated based on their mass to charge (m/z) ratio. The mass analyzer is often employed based on speed, duration, rate, and reaction.

The following are the mass Analyzer:

a. The quadrupole

b. Flight time

b. An ion trap

d. The FTICR (Fourier transfer ion cyclotron resonance)


The detector is an essential mass spectrometer equipment that generates current proportional to the number of ions that impact it. The detectors are:

Point Ion Collectors Detector: In this case, the ions collectors are fixed in a mass spectrometer.

Array Detector: An array detector is a group of point collectors arranged in a plane.


In forensic science: Toxicity testing, drug analysis, and trace analysis are done with LC-MS. Toxins in diverse materials can be detected using LC-MS with a small number of samples.

In doping test: The LC/ESI-MS in positive mode can be used to identify the doping substance 4-Methyl-2-hexane amine in urine.

In Pharmacokinetics: LC-MS is used to examine medication absorption, metabolism, and excretion.

In the determination of assay of drugs and intermediates: In the pharmaceutical sector, LC-MS is used to determine the assay of drug substances, drug products, intermediates, and their associated molecules.


The LC-MS is widely used in pharmaceutical, chemical, food, agrochemical, environmental, and forensic sectors. The technique determines pharmacological compounds’ and biological materials’ qualitative and quantitative composition.

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