Detection of Organic Contamination
Water supplies throughout the U.S. are showing unprecedented levels of contamination from drugs, antibiotics, hormones given to farm animals, and personal-care products such as lotions, beauty products, soaps, and hair dyes.
According to Maricar Tarun, Ph.D., an application scientist at EMD Millipore, at least 46 million Americans are supplied with drinking water that tested positive for at least one of these substances. Contaminants run the gauntlet, including acetaminophen, caffeine, codeine, nicotine, and sulfamethoxazole.
With water supplies deeply compromised, the question arises as to what extent these molecules wend their way into the high-purity water so essential to the operation of scientific laboratories.
Using reversed-phase HPLC with a quadrupole ion trap mass spectrometry system, Dr. Tarun and her co-workers examined water that had been subjected to a number of different purification regimes. They detected six pharmaceutical molecules in tap water, between 2 and 76 ng/L.
After reverse osmosis and deionization, Dr. Tarun was able to detect low nanogram levels of all the molecules except acetaminophen. In the HPLC-grade water tested, most of the molecules that were examined yielded levels in the range of 200 pg/L, yet one molecule, caffeine, was much higher, giving values of about 11 ng/L. In LC/MS grade bottled water, half of the antibiotics and drugs were undetectable, although caffeine still weighed in at ca. 10 ng/L. And this was even after an elaborate series of purification steps such as reverse osmosis, ion-exchange resins, UV photo-oxidation, and treatment with activated carbon.
Dr. Tarun noted that high-purity water plays a critical role in reversed-phase HPLC separations. Contaminants in the water used to prepare the aqueous mobile phase accumulate in the column and could be responsible for high background noise and other interference, rendering meaningless studies on such pressing questions as environmental contamination. Without a legitimate baseline, it will be difficult to rely on values obtained from samples.
Dr. Tarun’s work points out the difficulties that environmental scientists are faced with in an era when extremely powerful technology is available that can detect contaminants as rare as one in a billion of even one in a trillion. The amount of caffeine in one cup of coffee is 400 million times higher than what she detected in her water samples. Assigning health risks to such miniscule levels of contaminants would be virtually impossible. So while the health risks may be negligible or undetectable, clearly it is essential to monitor the water used in scientific investigations.