Used to measure isotope ratios in packaging and inks
LGC, the UK’s National Measurement Institute for chemical and bioanalytical measurement, is using mass spectrometry (MS) for the first time to measure variations of calcium (Ca) and lead (Pb) isotope ratios to identify counterfeit pharmaceutical packaging.
By applying this technique to look at Ca and Pb isotope ratios in the cardboard packaging and printing ink used in pharmaceutical cartons, scientists can now potentially distinguish the source of origin of packaging materials, thus providing evidence against drug counterfeiters for subsequent prosecutions.
The detection of counterfeit drugs and packaging has traditionally relied on a combination of visual examination and chemical analysis. However, as counterfeiting techniques are becoming increasingly sophisticated, more sensitive detection methods are required. Many counterfeit pharmaceuticals now contain the same active pharmaceutical ingredient as the genuine product, so their elemental composition is often very similar to that of the real drug. In addition, both genuine manufacturers and counterfeiters often combine a number of elements of packaging materials sourced from different suppliers, thus making it difficult to identify counterfeits that have been seized in different locations.
LGC scientists headquartered in Teddington, Middlesex, UK, have worked on a research project in collaboration with GlaxoSmithKline and funded by the UK National Measurement Institute. All naturally occurring elements consist of one or more stable isotopes and the isotopic profile of elements can reveal subtle variations depending on the source of origin. Advances in mass spectrometry have made possible the detection of these variations.
Described in a recently published primary paper*, LGC scientists used a laser ablation system coupled to a multicollector inductively coupled plasma mass spectrometer (LA-MC-ICP-MS) to measure and compare the Ca and Pb isotope ratios of nine pharmaceutical packaging samples.
As Ca is used in the cardboard/papermaking process and Pb is a major component of ink, both elements are expected to be present in packaging at relatively high concentrations. The results of the LGC study showed that, of the nine samples analysed, the five authentic samples displayed different Ca isotope ratios from those of the counterfeit samples. The Ca isotope ratios of two counterfeit samples known to come from the same country clustered together. Two further counterfeit samples, from different countries, also had similar Ca isotope ratios to the first two counterfeit samples analysed. Isotope ratio analysis of Pb showed similar clustering of results.
LGC’s Dr Ruth Hearn, team leader in chemical measurement and calibration, said: ‘Working in collaboration with GlaxoSmithKline was vital to the success of this project because it enabled LGC to gain first-hand insight to the problems faced by pharmaceutical companies in tackling drug counterfeiting.’
LGC is also using the same technique to provide high accuracy sulfur isotope ratio measurements to identify counterfeit pharmaceutical drugs.
* Application of laser ablation multicollector inductively coupled plasma mass spectrometry for the measurement of calcium and lead isotope ratios in packaging for discriminatory purposes, Rebeca Santamaria-Fernandez and Jean-Claude Wolff Rapid Commun. Mass Spectrom. 2010; 24: 1993–1999