Screening and identification of unknown contaminants in water destined to human consumption: A case study

As a response to a recent emergency case of suspected deliberate contamination of bottled drinking water addressed to sensitive personalities, samples were submitted to our laboratory for investigation; an analytical framework for wide screening and identification of unknown hazardous chemicals and microbiological agents in water has been developed and experienced for the purpose. The proposed approach combines several physico-chemical (inverse-phase liquid chromatography with spectrophotometric or mass spectrometric detection, suppressed ion chromatography, inductively coupled plasma–optical emission spectrometry, gas chromatography with mass spectrometric detection), microbiological (defined substrate technology) and biological assays (viability and macromolecular synthesis of cultured cells), thus allowing the detection of different classes of contaminants (inorganic and organic compounds, metals, algal toxins, bacterial indicators of faecal contamination, enteric pathogens, staphylococci, actinomycetes) and their effects.The application of the developed strategy to the suspected samples did not highlight the presence of specific and considerable risks for human health although a few organoleptic and microbiological parameters were compromised and water was not suitable for human consumption. Therefore, we were able to classify this episode as a water contamination threat instead of confirming an incident.The proposed screening-confirmatory analytical scheme can be a valuable tool for obtaining conclusive and relatively rapid results in investigations concerning accidental or intentional contamination of drinking water.