The developed direct method was capable of the quantification of more than 30 elements at concentration levels of 10−8 wt.%, with acceptable levels of precision and accuracy, from an aqueous suspension of just 0.1 mg mL−1 DND.
Inorganic arsenic exposure in drinking water has been identified as a cardiotoxic element at concentrations seen in drinking water supplies around the world which strengthens the importance of ensuring public water supplies meet the U.S. EPA maximum contaminant level (MCL) of 10 μg/L (U.S. EPA 1998).
Moreover, the high errors should be expected in the determination of elements at the concentrations below 1% (m/ m).
The new miniaturised and automated 1,728 multiwell Screen format presented here has enabled the analysis of a large multidimensional space (Screen 1: N and P full factorial; Screen 2: ten elements at three concentrations) for nutrient sufficiency (and minimisation of toxic effects) at three levels.
Additional laboratory tests with respect to the societal questions: Uranium 238: concentration in urine (Inductively Coupled Plasma-Mass Spectrometry [ICP-MS] analyser, Finnigan Mat Element) and, at concentrations above 50 ng/l or above 50 ng/g creatinine, also the ratio of uranium 235/238 isotopes [ 52].
Inductively coupled plasma mass spectrometry (ICP-MS) has become the most widely accepted analytical technique for simultaneously measuring a range of trace elements at variable concentration levels (Durrant 1999; Günther and Heinrich 1999; Günther et al. 2000; Sylvester 2001a; Heinrich et al. 2003).
Both pemba and kichuguu contained chemical elements at varying concentration, mostly above MRLs.
On a small portion of an original log, from which a wood layer about 5 mm thick had been removed by carving (during a recent repair), the indicator elements were found at concentrations lower than on an intact spot on the same log.
The two nuclear techniques have allowed to reach elevated sensibility/accuracy levels for determining elements at very low concentrations (trace and ultra-trace levels).
The interactions between known toxic trace elements at biologically relevant concentrations shown here demonstrate a clear need to rigorously review methods by which national/international agencies assess health risks of chemicals, since exposures may commonly occur as complex mixtures.
