Distribution of Trace Metals in a Ling (Genypterus Blacodes) Fish Fillet.

The distribution of trace metals in a ling (Genypterus blacodes) fish fillet was determined from ICP-MS measurements of digests prepared using nitric acid and hydrogen peroxide, followed by microwave digestion. Most trace elements were inhomogeneously distributed in the muscle tissue of the ling with a non-linear increase in concentration towards the tail end of the fillet. This distribution pattern may be connected to the size variation of the individual muscle cells or the change in the ratio of connective tissue to muscle tissue, suggesting that the observed inhomogeneity of muscle elemental distribution may be inherent to all fish species. The concentration of an element in a sample of fish muscle tissue thus depends on the physical location within the fish from which the sample was dissected. Significant differences in trace element concentrations were also detected between the red and white muscle fibres of ling, as well as between the belly flap and the rest of the musculature

Comparison of Digestion Methods for ICP-MS Determination of Trace Elements in Fish Tissues.

A comparison is presented of six methods involving nitric acid in conjunction with other reagents to digest three certified marine biological samples (DOLT-3, DORM-3, IAEA-407) and a fish bone homogenate (prepared from Merluccius australis). An inductively coupled plasma-mass spectrometer with an octopole collision cell was used to determine up to 40 elements (Li, B, Na, Mg, Al, K, Ca, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Rb, Sr, Y, Ag, Cd, Cs, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb, Lu, Pb, Th, U) in the digests. These results were assessed in terms of their accuracy and precision, and a flow chart was developed to aid the selection of the optimal digestion method. Although none of the methods was found to give accurate determinations for all elements in the different reference materials, a relatively simple method involving nitric acid and hydrogen peroxide heated in a domestic microwave oven gave the most acceptable results

Recent Advances in Structure and Reactivity of Dissolved Organic Matter in Natural Waters

The goal of our research is to better understand the structure and reactivity of natural dissolved organic matter (DOM) in aquatic environments. A more detailed knowledge of these DOM characteristics would lead to a better understanding of carbon cycling in natural waters and processes associated with water treatment using free radical chemistry. Our specific interest in DOM in natural waters is several-fold: 1) the photochemical formation of reactive oxygen species, 2) photobleaching of the DOM in coastal oceans, and 3) using chromophoric DOM (CDOM) as a tracer of water masses and in carbon cycling. Our interest in water treatment is that DOM is the major sink of hydroxyl radicals employed in advanced oxidation processes for the destruction of pollutants and thus adversely affects the efficiency of the process. We are using the techniques of radiation chemistry to explore the fundamental free radical and redox chemistry of DOM. We have initiated a study of the free radical reactions of DOM using isolated fractions of Suwannee River fulvic and humic acids and isolates from various anthropogenic sources. We are also investigating the use of model compounds in an attempt to understand the free radical transients formed from DOM either as a result of free radical reactions or photochemical reactions

Flow Injection Analysis of H\u3csub\u3e2\u3c/sub\u3eO\u3csub\u3e2\u3c/sub\u3e in Natural Waters Using Acridinium Ester Chemiluminescence: Method Development and Optimization Using a Kinetic Model

Chemiluminescence (CL) of acridinium esters (AE) has found widespread use in analytical chemistry. Using the mechanism of the reaction of H2O2 with 10-methyl-9-(p-formylphenyl)acridinium carboxylate trifluoromethanesulfonate and a modified flow injection system, the reaction rates of each step in the mechanism were evaluated and used in a kinetic model to optimize the analysis of H2O2. Operational parameters for a flow injection analysis system (reagent pH, flow rate, sample volume, PMT settings) were optimized using the kinetic model. The system is most sensitive to reaction pH due to competition between AE hydrolysis and CL. The optimized system was used to determine H2O2 concentrations in natural waters, including rain, freshwater, and seawater. The lower limit of detection varied in natural waters, from 352 pM in open ocean seawater (mean, 779 pM ± 15.0%, RSD) to 58.1 nM in rain (mean, 6,340 nM ± 0.92%, RSD). The analysis is specific for H2O2 and is therefore of potential interest for atmospheric chemistry applications where organoperoxides have been reported in the presence of H2O2

Methods for reactive oxygen species (ROS) detection in aqueous environments

This review summarizes direct and indirect analytical methods for the detection and quantification of the reactive oxygen species (ROS): 1O2, O2·−/HOO·, H2O2, HO·, and CO3·− in aqueous solution. Each section briefly describes the chemical properties of a specific ROS followed by a table (organized alphabetically by detection method, i.e., absorbance, chemiluminescence, etc.) summarizing the nature of the observable (associated analytical signal) for each method, limit of detection, application notes, and reaction of the probe molecule with the particular ROS