Abstract of PhD Thesis

The Development of Liquid Chromatography-Mass Spectrometry (LC-MS) Methods for the Determination of Hepatotoxins in Irish Freshwaters, Cyanobacteria and Drinking Water

Orla Allis, Cork Institute of Technology (2007)

The occurrence of cyanobacterial water blooms can create a significant water problem, as certain species are capable of producing natural toxins. Microcystins and nodularin are the most frequently reported hepatotoxins. These are known to cause severe and sometimes fatal poisoning episodes in animals and humans when present in drinking water in sufficient high concentrations. For this reason, the availability of sensitive, selective, rapid and reliable methods for the detection of these toxins is essential.

Liquid chromatography coupled with mass spectrometry is favoured for its selectivity and sensitivity. However, one of the most significant problems associated with this methodology is the requirement for lengthy sample pre-concentration steps such as solid phase extraction. An alternative in-tube solid phase microextraction liquid chromatography coupled with tandem mass spectrometry method, using multiple reaction monitoring experiments on a triple stage quadrupole mass spectrometer, was developed and validated in lake water and bottled drinking water.

A more sensitive, selective and rapid liquid chromatography coupled with mass spectrometry method was also developed and validated in lake water, cyanobacteria, chlorinated tap water and bottled drinking water using a security guard cartridge system as an analytical column. Monitoring of Irish lakes for microcystins and nodularin was accomplished using the validated liquid chromatography coupled with mass spectrometry methods as well as other analytical and biological methods.

The lack of commercially available standards and internal standards for hepatotoxin analysis led to the development of an improved isolation protocol for microcystins and an isotope labelled MC-LR (internal standard). This novel internal standard for microcystin and nodularin analysis was successfully cultivated and isolated. Following its isolation, the compound was compared with nodularin as an internal standard.