Molecular “fingerprinting” made quick and easy

Five clicks with a computer mouse are all that analysts of the Central Analytical Facility at Stellenbosch University now need to do to perform polymer characterisation and bio-molecular identification – thanks to a new mass spectrometer (MS) worth R7 million that is currently on loan from supplier Bruker Daltonics South Africa.
“This equipment is very fast and user-friendly, allows for accurate identification, is cost-effective and uses a very simplified sample preparation method compared to other analysis techniques,” says CAF analyst Ms Nadine Pretorius, who is putting the Bruker Daltronics UltrafleXtreme through its paces in fingerprinting and typing a variety of biomolecules, synthetic polymers and complex molecules. In turn, colleague Ms Wernich Foit is responsible for biological and environmental samples such as yeasts, fungi and bacteria.
Up to 384 samples can be prepared at a time on a single target plate. Depending on the type of molecule that is being analysed, the work can be done in about two hours.
The state-of-the-art equipment ensures soft-ionization of samples through the MALDI-TOF-MS (Matrix Assisted Laser Desorption Ionization – Time of Fight – Mass Spectrometry) technique, and is housed in the Polymer Science building in the Department of Chemistry and Polymer Science.
The mass spectrometer is used to characterise large molecules without fragmenting them. “With this we can accurately determine the molecular weight or unique “fingerprint” of a sample, which helps with its further identification,” explains Ms Pretorius.
“It’s not an invasive technique and does not cause the fragmentation of a molecule,” she says. A sample is placed onto a target plate which is then crystalized. This is then subjected to laser beam pulses and desorbed under high vacuum.
The system comes equipped with a Bruker Daltonics Biotyper and Polytools software packages. “This offers the complete solution for fast analysis, including the calculation of the average molecular weights of synthetic polymer chains,” says Ms Pretorius.
End-groups and structural information can also be obtained. Such tools are very helpful when doing standardisation tests or as a quality control measure to ensure that, for example, property specific batches of paints and plastics are all produced according to the same formula.
The system can also be used to identify mystery bacteria, viruses or other biomolecules such as biopolymers, oligonucleotides, proteins, peptides and sugars. In the Biotyper application, dendrograms can be drawn of the identified species, as well as of the principal components of a group of samples.
“Because you do not need to incubate a sample before you can analyse it, it’s ideal to use when you need a quick result, such as in medical pathology,” Ms Foit explains the advantages of the simplified sample preparation methods. “When someone is ill because of some unknown cause, there’s simply no time to waste to find out what lies at the root of it.”
“Because we can characterise or “fingerprint” specific species or strains, this MS system is of value for among others food scientists, biochemists, botanists, wine biotechnologists and environmental specialists,” she believes.
While on loan to SU, the equipment is available for use by academics and industry partners alike. For further information contact Ms Pretorius at Nadine@sun.ac.za, 021 808 9380 or visit www.sun.ac.za/caf

Ms Wernich Foit and Ms Nadine Pretorius