It may seem like an odd marketing campaign but "Come visit Spain, the European point of entry for cocaine" remains apt.

A study of randomly selected Spanish euro notes carried out by chemists at the University of Valencia (UV) has shown that they contained traces of cocaine at an average concentration of 155 micrograms, which is the highest rate in Europe, according to an article published in the latest issue of Trends in Analytical Chemistry. The researchers also carried out a comparative study of the methods currently used in detecting the presence of cocaine on bank notes worldwide.

The most recent report from the United Nations Office on Drugs and Crime warns that Spain is still the major point of entry of cocaine into Europe. In 2006, 41% of all hauls of the drug made on the continent were made on Spanish soil, where 50 metric tonnes were seized, followed by Portugal, with 35 metric tonnes. The UN also says the rate of cocaine use doubled in Spain between 1999 and 2005, increasing from 1.6% to 3% of those aged between 15 and 64, which is more than twice the rate for western Europe as a whole (1.2%).

“The latest technology means we can now carry out quantitative analysis of cocaine traces on any bank note, and as a result we can confirm that – at least in Spain – traces of the drug are found not only on notes that have been in direct contact with it, but on nearly all the notes in circulation,” said Miguel de la Guardia, co-author of the study and a professor in the Analytical Chemistry Department of the UV, in an interview with SINC. He explained that this was due to “cross contamination” between bank notes, as well as in money counting machines used by banks.

The chemist told SINC that the methods used to extract cocaine from the bank notes and to analyse it depended upon whether it was necessary to detect the drug quickly, in which case direct application methods are used (in which the drug is not separated from the bank note), such as thermal dissolution, with detection by mass spectrometry, ionic mobility spectrometry, or immune testing (with an antigen-antibody recognition system).

Mass spectrometry is also used if the priority is to determine the exact amounts of cocaine on a note. However, in this case it is necessary to first separate the drug from the notes, using methods such as gas chromatography, liquid chromatography or capillary electrophoresis, using organic solvents.

The study also analyses previous studies highlighting the concentrations of cocaine found in different currencies around the world, as well as the results of the random sample of Spanish bank notes gathered by the Valencian chemists, which detected concentrations of up to 889 microgrammes of the drug on some notes.

In the United States, which has the most highly contaminated bank notes of any country in the world, dollar bills containing more than 1,300 microgrammes of cocaine have been registered, although the average values were between 2.86 and 28.75 microgrammes, varying according to the year and city.

The study also reveals that German euro bank notes have a cocaine concentration traces five times lower than that of the Spanish ones. With Irish bank notes, one statistic indicates that of 48 notes studied the highest concentration found was 0.576 microgrammes.

Another study, carried out on 356 Swiss franc notes, found that only 6% were contaminated with the drug (at concentrations above one nanogramme per note). The researchers were unable to find any quantitative data in the scientific literature relating to British pounds, but semi-quantitative data from a few years ago suggested that between 40% and 51% of bank notes were contaminated with cocaine, at levels of 0.0011 microgrammes per note.

The publication points out that there is an “unequivocal” relationship between the high levels of cocaine found in both American dollar bills and Spanish euro notes and the high consumption of the substance in both countries.

De la Guardia believes that cocaine “has become rooted in Spanish society, and is playing Russian roulette with the neuronal development of an entire generation”, and that for this reason greater efforts must be made to reduce consumption, as well as to destroy the glamorous image of cocaine “which is often portrayed by the media”. “I find it profoundly embarrassing that we now all have cocaine in our wallets,” the researcher added.

Article: S. Armenta, M. de la Guardia. “Analytical methods to determine cocaine contamination of banknotes”. Trends in Analytical Chemistry 27 (4): 344-351, 2008