Analytical chemistry.

By-products produced during water purification may present a threat to health in certain circumstances. One alternative to chlorination is ozonolysis. However, any bromate formed during this process may be hazardous since it is a possible human carcinogen. A very sensitive analysis method has been developed to determine bromate in drinking water at sub-microgram per litre levels without interference from bromide (A R Elwaer, C W Mcleod and K C Thompson, Anal. Chem., 2000, 72, 5725). A microcolumn was used with a flow injection system to provide rapid on-line separation of bromide and bromate from the sample. The anion exchanger column was based on polystyrene polymer, and the bromate and bromide were subsequently eluted off using ammonium malonate. This material offered the advantage that bromate was eluted before bromide, thereby reducing any problems with memory effects from high levels of bromide present in the sample. Detection of the two analytes was achieved using an inductively coupled plasma-mass spec trometer (ICP-MS), by monitoring bromine at mass 79 (see Figure 1 for a schematic of the apparatus). The anion exchanger helps to eliminate interferences from cations, such as potassium, calcium, magnesium and sodium, all which would be present at high levels in water. The approach offers short analysis time (10min per sample), low limits of detection (0.l3[micro]g/L bromate based on a 500[micro]L sample injection) and good precision. The validity of the method was checked by an EC-sponsored inter-laboratory trial and was found to offer excellent long-term measurement precision.

High-performance liquid …