Simultaneous quantitative determination of thirteen urea pesticides at sub-ppb levels on a Zorbax SB-C18 column.

A simple multi-residue method is described for simultaneously determining ten urea and three benzoylurea pesticides residues in drinking water with quantitation limits below the European regulatory limit of 0.1 microgram/l. The residues were extracted from drinking water with dichloromethane and analysed by HPLC on a Zorbax 5 microns SB-C18 column with diode array detection (DAD) at 240 nm. Recoveries were determined by spiking drinking water with 13 pesticides (benzthiazuron, metoxuron, monuron, fluometuron, isoproturon, diuron, linuron, chloroxuron, chlorbromuron, diflubenzuron, neburon, triflumuron and flucycloxuron) at the 0.05-0.50 microgram/l level.

Criteria for reference value assessment of elements in human tissues.

The availability of updated and reliable reference values for elements in biological tissues and fluids plays a key role in the correct planning and performance of clinical, toxicological and environmental studies. The basic principles for a proper analytical approach in order to obtain such data are outlined. This in turn should significantly reduce the wide range of figures reported for most elements as "normal" intervals in the scientific literature. Some applications of these guidelines are illustrated in detail in the case of human lungs, liver and kidneys for which tentative reference values are assessed for a number of minor and trace elements, namely, Al, Ba, Cd, Cr, Cu, Li, Mg, Mn, Pb, Sr, V and Zn.

Reference values for elements of toxicological, clinical and environmental interest in hair of urban subjects.

A monitoring campaign has been undertaken to ascertain the reference concentration ranges for a number of minor and trace elements in hair of healthy urban subjects under age 15. An outline of criteria and methods lying at the root of a sound and reliable experimental approach are presented with special regard to such crucial steps as study planning, sampling, storing, pretreatment, analysis and evaluation of results. Determinations were carried out mainly by inductively-coupled plasma atomic emission spectrometry (ICP-AES) given the wide investigative potential and inherently multielemental character of this technique. The results obtained so far regard 100 youngsters allowing reference intervals for Al, As, Ca, Cd, Co, Cr, Cu, Fe, Mg, Mn, Mo, Ni, P, Pb, Se, Ti, V and Zn to be established for the population group tested. Finally, further developments of this activity are highlighted, particularly emphasizing the diagnostic capabilities of hair analysis.