There's something fishy in the water

By Dr Matt Wilkinson

- Last updated on GMT

Related tags: Acetic acid

A new method to identify the extent of contamination of our
waterways by pharmaceutical products has identified three products
previously unknown to accumulate in fish.

Researchers from Baylor University in the US, have developed a new liquid chromatography - tandem mass spectrometry (LC-MS/MS) screening method for detecting 25 pharmaceutical and personal care products (PPCPs) in fish tissue samples. The research, to be published in the next issue of Analytical Chemistry​, describes the optimisation of the new methodology and how the researchers used it to discover the presence of three PPCPs (diphenylhydramine, diltiazem and carbamazepine) that have previously not been observed to accumulate in fish. In recent years, pharmaceutical companies have come under increasing pressure to ensure clean water discharge from manufacturing plants to avoid environmental contamination. Lately, concern has also been expressed over the disposal of unused pharmaceuticals by consumers - often by flushing down the drain. Although companies have no control over this, the potential environmental impact could turn out to be just as severe to aquatic life. Many protocols have been previously described for detecting PCCPs in water, sediment and biosolids, but the majority of these have focussed on single compounds or compound classes. Recent interest has shifted to the simultaneous analysis of numerous compounds with different physical and chemical properties to gain more widespread contamination information with the minimum expenditure of time and money. The latest research led by Dr Kevin Chambliss, assistant professor of Chemistry at Baylor University has optimised conditions for the extraction of PPCPs from contaminated tissue as well as their separation and analysis using LC-MS/MS. The 25 target analytes were chosen according to the number of US prescriptions dispensed in 2005, the variability of their structure and physicochemical properties as well as their relative frequency of occurrence in the environment. A 1:1 mixture of 0.1M aqueous acetic acid and methanol led to extraction efficiencies of greater that 60 per cent for 24 of the 25 compounds. An optimised LC-MS/MS setup using a nonlinear gradient of 0.1 per cent formic acid and methanol allowed efficient separation and analysis within 50 minutes. After calibration and validation using spiked fish samples, the technique was tested on fish found 650m downstream from an effluent discharge into Pecan Creek in Texas, US. While the technique was not sensitive enough to detect two antidepressants: fluoxetine and sertaline, that have previously been identified in fish at very low levels from the stream, all samples tested positive for norfluoxetine (a drug metabolite), diphenhydramine (an antihistamine), diltiazem (a hypertension treatment) and carbamazepine (a treatment for epilepsy and bipolar disorder) at concentrations ranging from 0.11 to 5.14 nanograms of compound per gram of fish tissue. The identification of the latter three of these compounds is the first time they have been observed to bioaccumulate in fish showing the importance of trying to minimise the contamination of water ways. These last three compounds have never previously been observed to bioaccumulate in fish, demonstrating the sensitivity and significance of the method, as well as the importance of efforts to minimise contamination of our waterways.

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