Matrix-Assisted Laser Desorption/Ionization (MALDI)

MALDI is a sample preparation and ionization technique which is used to prepare sample matter before it can be analyzed through mass spectrometry. MALDI is widely applied in analyzing delicate samples, such as peptides, proteins, lipids and other large molecules that are prone to decomposition if more harsh ionization techniques are used.

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What is MALDI and how does it work?

Matrix-Assisted Laser Deposition/Ionization is a sample preparation technique which is used to prepare an analyte so that it can be observed through mass spectrometry. This is done in a gentle way, which usually allows the molecules in the sample to be analysed without significant fragmentation. The process begins by mixing the analyte with a matrix; this is usually a crystalline material dissolved in a solvent. The analyte/matrix solution is then spotted onto a metal plate, ready to begin the ionization process. Next, the solution is irradiated with pulsed laser light. This causes the solution to desorb from the surface of the plate, removing both the matrix and the analyte. Here, the matrix helps to protect the analyte and prevents damage from the intense laser. During this process, a proton is transferred from a matrix molecule to the analyte. This essentially ionizes the analyte, without any need for harsher methods which could damage the molecule. Once the analyte is ionized, it can be passed on to a mass spectrometer for analysis. Most often, MALDI is coupled with Time of Flight - Mass spectrometer (ToF-MS), which causes the ions to become separated based on their individual masses and charges as they travel the length of the machine. Once the ions reach the end of the spectrometer they are detected, so that their information can be logged. Through this, data on the masses and concentrations of the components within the sample can be collected.

Why is MALDI used?

MALDI is what is referred to as a “soft” ionization technique, which means that it is able to ionize molecules of a sample without causing them to break down into fragments. Often, ionization techniques involve removing electrons from the analyte, which in some cases can be too destructive. Here, ionization occurs through a proton transfer, which is far less destructive to delicate molecules. Furthermore, during the desorption process, the matrix helps to absorb the energy from the laser and protects the analyte from being over-exposed and breaking down. Overall this results in a technique that allows molecules to be analyzed without damaging them first, which in certain fields can be essential.

Are there any limitations of MALDI?

Due to the need for an excess of a matrix, the analyte can sometimes be slightly obscured during analysis. This means that in some cases, low levels of sample matter require extra optimization steps in order to achieve high-quality results. Furthermore, particularly large biomolecules can be difficult to identify if existing mass spectrum data does not exist to use as a comparison. Hence, it is always worth considering the type of sample to be analyzed, and whether MALDI is the most appropriate option.

Sample requirements and preparation

Before analysis can take place, the sample must first be dissolved in a suitable matrix solution. These can be based on water, organic solvents or a combination of both, which allows both polar and nonpolar molecules to dissolve. Ideally, the sample should be as pure as possible. Both organic and inorganic contaminants can affect the quality if the results gathered, so should be avoided as best possible.

Need a MALDI analysis?

Measurlabs offers MALDI analyses of high quality with fast results and affordable prices. If you have any questions about your sample or its suitability for the method, our experts are always happy to help. You can contact us through the form below or by emailing us at info@measurlabs.com.

Suitable sample matrices

  • Peptides
  • Proteins
  • Carbohydrates
  • Polymers

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Frequently asked questions

What is MALDI commonly used for?

MALDI is an ionization technique used for preparing delicate samples for mass spectrometry analyses.

What are the limitations of MALDI?

Low levels of sample matter might require extra optimization steps in order to achieve high-quality results. Furthermore, particularly large biomolecules can be difficult to identify if existing mass spectrum data does not exist to use as a comparison.

What kind of samples are suitable for MALDI?

For examples peptides, proteins, carbohydrates and polymers are suitable for MALDI.

What is Measurlabs?

Measurlabs offers a variety of laboratory analyses for product developers and quality managers. We perform some of the analyses in our own lab, but mostly we outsource them to carefully selected partner laboratories. This way we can send each sample to the lab that is best suited for the purpose, and offer high-quality analyses with more than a thousand different methods to our clients.

How does the service work?

When you contact us through our contact form or by email, one of our specialists will take ownership of your case and answer your query. You get an offer with all the necessary details about the analysis, and can send your samples to the indicated address. We will then take care of sending your samples to the correct laboratories and write a clear report on the results for you.

How do I send my samples?

Samples are usually delivered to our laboratory via courier. Contact us for further details before sending samples.

MALDI is a sample preparation and ionization technique often used to prepare sample matter before analyzing it with mass spectrometry. MALDI is widely applied in analyzing delicate samples, such as peptides, proteins, lipids and other large molecules that are prone to decomposition if more harsh ionization techniques are used. Measurlabs offers quality analyses with MALDI in top laboratories around the world.