LC-MS analysis

What is LC-MS analysis used for?

One common use of LC-MS is specific migration testing of food contact materials, where the method is used to quantify the migration of specified toxicologically concerning substances from the contact material to a food simulant. Examples of this include bisphenol A testing and primary aromatic amine (PAA) screening. Similarly in the food and feed industries, LC-MS can be used for mycotoxin testing and for identifying and quantifying other unwanted contaminants.

LC-MS is also used in biochemical research to investigate proteins and other large molecules and in pharmaceutical development for research and quality control. In environmental analysis, LC-MS is commonly used to analyze water, soil, and other natural samples. Its ability to separate compounds based on molecular weight also makes it indispensable in the analysis of large molecules in polymer and material science.

How does LC-MS work?

LC-MS is a technique of two halves. Firstly, the sample is separated through liquid chromatography. This involves passing it through a column containing a stationary phase, which is usually silica or another inert solid, and a mobile phase, which is a solvent. Different compounds will pass through the column at different rates, which effectively separates them, staggering the times at which they reach the end of the column.

As each component reaches the end, it enters the mass spectrometer section. Here, each chemical species is ionized and accelerated through a flight chamber. The effect of the electric and magnetic fields in the chamber causes the ions to be separated based on their respective masses and electrical charges. As they reach the end they are detected, which creates a log of the different molecular weights that have passed through the system.

Sample requirements

LC-MS samples must be able to pass through a liquid chromatography column, that is, they must be in the form of a liquid or solution. Solid samples can be tested if they are first dissolved in a suitable solvent. 

Advantages of LC-MS

LC-MS can detect components within a solution down to parts per million (ppm) concentrations, making it incredibly sensitive. The method can be used on a wide variety of sample types, and can easily detect several components in a sample, even helping to identify unknown components.

Limitations of LC-MS

LC-MS is a destructive technique, as samples are ionized and broken apart during the latter half of the analysis. It also has a slower throughput than some less complicated techniques, such as GC-MS. Certain solutions and contaminants can affect the results gathered from LC-MS and therefore may not be suitable for testing. If the target analytes are fluorescent (e.g. certain vitamins or melatonin), the highly selective fluorescence detector used in HPLC-FLD can be used instead to minimize interference from contaminants or the solvent.

What is liquid chromatography-tandem mass spectrometry (LC-MS/MS)?

LC-MS/MS is fundamentally similar to standard LC-MS. The difference is that the second half is replaced by a technique called tandem mass spectrometry (denoted as MS/MS). In tandem mass spectrometry, the analyte is passed through two mass spectrometry steps in sequence, enabling more in-depth analysis and improved sensitivity. This makes LC-MS/MS ideal for detecting trace quantities of analytes, such as nitrosamine impurities in pharmaceuticals, PFAS in environmental samples, or persistent organic pollutant (POP) traces in food.

Do you need an LC-MS analysis?

Measurlabs offers high-quality analytical services with techniques including LC-MS, HPLC-MS, and UPLC-MS/MS. Check out our selection of liquid chromatography-based analyses and typical price ranges in our online catalog. To get a customized offer including for example volume discounts for large numbers of samples, contact us through the form below.