Antimicrobial compounds (triclosan and triclocarban) in sewage sludges, and their presence in runoff following land application.

The reuse of treated municipal sewage ('biosolids') on land is an effective method to divert waste away from landfill and to use an alternative, low cost method of fertilisation. While legislation has mainly focused on the control of nutrient and metal application rates to land, other potentially harmful emerging contaminants (ECs) may be present in biosolids. Up to 80% of municipal sewage sludge is reused in agriculture in Ireland, which is currently the highest rate of reuse in Europe. However, unlike other countries, no study has been conducted on the presence of ECs across a range of wastewater treatment plants (WWTPs) in this country. This study evaluated the concentrations of two ECs in sewage sludge, the antimicrobials triclosan (TCS) and triclocarban (TCC), and their presence in surface runoff following land application in controlled rainfall simulation studies. In 16 WWTPs, concentrations of TCS and TCC were 0.61 and 0.08µgg-1, which is at the lower end of concentrations measured in other countries. The concentrations in runoff post land application were also mainly below the limits of detection (90ngL-1 for TCS, 6ngL-1 for TCC), indicating that runoff is not a significant pathway of entry into the environment.

An improved method for clenbuterol screening using high resolution selected ion recording.

A method has been developed using reliable GC derivatization techniques interfaced with a high resolution mass spectrometer. The method has proved successful for the detection of low levels (less than 1 ppm) of clenbuterol in complex biological matrices. Selected ion recording of two characteristic isotopic fragment ions provides a specific mode of detection by verifying the GC retention time of these ions and also by comparing their relative abundance. Analysis of urine samples demands higher mass spectrometric resolution, and 40 000 (10% valley) was found to be a prerequisite for accurate integration of the drug-related chromatographic peaks. The method developed is suitable for adaptation to a completely unattended automated routine incorporating sample injection, storage and retrieval of source tuning parameters, and data processing.

Determination of the amino acid sequence of apamin by tandem mass spectrometry.

A new strategy has been developed for the determination of the amino acid sequence of apamin, a two disulfide-bond neurotoxic oligopeptide. Relative molecular mass up to about 2000 was determined using electrospray mass spectrometry. This technique shows that three basic amino acid residues are present in apamin. A hydrophobic tryptic digest fragment was sequenced using fast-atom bombardment combined with tandem mass spectrometry. But the full sequence has been directly observed using a tandem mass spectrometer: the daughter-ion mass spectrum of protonated molecules of dithiothreitol-reduced apamin gives the sequence.