Graham Cooks, professor of chemistry at the university and leader of the team that the developed the analysis method, said the technique is based on ambient ionization using a low-temperature plasma (LTP) probe combined with tandem mass spectrometry (MS/MS).
He said that it allows detection and quantitation of the industrial chemical in milk powder, whole milk and other products at levels down to low parts per billion (ppb) in analysis times in about 25 seconds: “It is the fastest method so far reported. It is also very specific and has sensitivity well below US Food and Drug Administration (FDA) recommended levels.”
Dairy scandal
China’s dairy industry was put at the heart of a global scandal in 2008, when thousands of children were hospitalised and at least six died after traces of melamine found its way into milk. Melamine is a chemical that can make it appear there is more protein in a product, and has been linked to causing kidney stones and other health problems.
While China bore the brunt of the contamination fears, products around the world ranging from infant formula to confectionery were recalled in fears over ingredient sourcing in the country.
Research trigger
Cooks explained that trigger for the development of the melamine test was the guidelines issued by the FDA back in November limiting the chemical in dairy products to 1 part-per-million (ppm) or less:
"We took it as a challenge to use simpler instrumentation and to develop a faster method that allows the testing to be done on site and does not require pre-treatment of samples,” said Cook.
High throughput
He said that ambient ionization methods, such as the low-temperature plasma ionization employed by the Purdue group, can greatly reduce the time-intensive and sometimes difficult requirements of mass spectrometers:
"The experiment can be done in a high-throughput fashion, at a rate of two samples per minute. This method provides the sensitivity, specificity and the quantitative accuracy needed to meet the current urgent requirements for a simple and reliable melamine determination in complex mixtures."
He explained that the ionization source of the research project was developed over a period of a few months but as a general method, not aimed at melamine, with the melamine experiments completed in about ten days.
"Even without direct contamination, trace amounts of melamine sometimes make their way into consumable products because melamine is used in manufacturing and is found in many packaging materials," Cooks said. "At trace levels, the chemical is not known to be a health threat and has been deemed safe by the FDA. Our analysis provides a way to determine whether the amounts present exceed safe levels."
Availability
He told FoodProductionDaily.com that a patent has been applied for in relation to the detection method, while discussions in regards to its commercialization are ongoing.
The research team, he continued, have been involved in several other food safety related projects in the past few months including studies focused on pesticide residues, components in olive oil and natural sweeteners.
Their work in developing a test for melamine in milk, which was funded by the US Office for Naval Research, was published in the journal Chemical Communications.