Simultaneous determination of the Cd and Zn total body burden of individual, nearly microscopic, nanoliter-volume aquatic organisms ( Hyalella azteca) by rhenium-cup in-torch vaporization (ITV) sample introduction and axially viewed ICP-AES.

Abstract

The Cd and Zn total body burden of individual, up to 7-day-old aquatic organisms (Hyalella azteca benthic amphipod) with an average volume of approximately 100 nL was determined simultaneously by using rhenium-cup (Re-cup) in-torch vaporization (ITV) sample introduction and an axially viewed inductively coupled plasma atomic emission spectrometry (ICP-AES) system. The direct elemental analysis capabilities of this system (i.e., no sample digestion) reduced sample preparation time, eliminated contamination concerns from the digestion reagent and, owing to its detection limits (e.g., in the low pg range for Cd and Zn), vit enabled simultaneous determinations of Cd and Zn in individual, neonate and young juvenile specimens barely visible to the unaided eye (e.g., nearly microscopic). As for calibration, liquid standards and the standard additions method were tested. Both methods gave comparable results, thus indicating that in this case liquid standards can be employed for calibration, and in the process making use of the standard additions method unnecessary. Overall, the ITV-ICP-AES approach by-passed the time-consuming acid digestions, eliminated the potential for contamination from the digestion reagents, improved considerably the speed of acquisition of analytical information and enabled simultaneous determinations of two elements using individual biological specimens.