Detecting environmentally important

Application of Combination Ion Source To Detect Environmentally Important Compounds... 

Metal oxide semiconductors in detecting environmentally important gases... 

Recent Uses of Solid-Surface Luminescence Analysis in Environmental Analysis. Vo-Dinh and coworkers have shown very effectively how solid-surface luminescence techniques can be used for environmentally important samples (17-22). RTF has been used for the screening of ambient air particulate samples (17,18). In addition, RTF has been employed in conjunction with a ranking index to characterize polynuclear aromatic pollutants in environmental samples (19). A unique application of RTF reported recently is a personal dosimeter badge based on molecular diffusion and direct detection by RTF of polynuclear aromatic pollutants (20). The dosimeter is a pen-size device that does not require sample extraction prior to analysis. 

An HPLC-CL determination of environmentally important chlorophenols was reported by using 10-methyl-9-acridinium carboxylate as a CL label. A two-step derivatization was used to produce the CL derivatives (Fig. 10). Following the separation under reversed-phase conditions, the CL reaction was performed by the base-catalyzed postcolumn oxidation. The quantum efficiency was dependent on the species of analytes. The detection limit of chlorophenols (S/N = 3) ranged from 300 amol to 1.25 fmol per injection (Fig. 11) [52],... 

The use of MPc complexes as electrocatalysts for the detection of analytes relies on the formation of modified electrodes. Thiol, alkylthio, or arylthio substituted MPc complexes readily form self-assembled monolayers (SAMs) on gold. Amino substituted MPc complexes can easily be electropolymerized onto electrodes. Direct adsorption of the monomer onto electrodes (especially carbon electrodes) also occurs. The modified electrodes are then employed for detection of analytes ranging from neurotransmitters, thiols, phenols, and other biologically and environmentally important molecules. 

The role of aromatic photonitration and photonitrosation processes in natural waters is still not clearly understood. It is, however, very interesting to report that nitration and nitrosation of monolinuron have been observed upon photolysis of nitrate and nitrite at environmental concentration levels [144], Studies on the environmental importance of such reactions will indeed benefit from the use of HPLC-MS-MS techniques for both process studies and field analysis, as they allow much lower detection limits to be reached when compared with traditional HPLC techniques. In the case of process studies, it would be very interesting to determine the extent at which the pathways observed for the photonitration and photonitrosation of aromatic compounds at fairly high concentration levels can be extrapolated to environmental conditions. 

Despite the fact that immunoassays can be sensitive, specific and rapid, their application to detect compounds of environmental importance has been limited to relatively few laboratories (7-10). This symposium volume serves an important function since it focuses on the current status of the immunochemical methods being used for environmental analyses. Many of the accompanying papers consider the basic principles and essential steps in setting up immunoassays, i.e. the covalent linkage of small molecules to carrier proteins, immunization with these... 

Environmentally important anions such as sulfide and cyanide can be determined very sensitively via amperometric detection. For their separation on a conventional Ion... 

A similar concept was used for other environmental applications, for example, phenoxy acids, sulfonureas, phenolic compounds, and other environmentally important persistent pollutants [68, 76, 141, 143, 155-166]. Also, in the same manner, several drugs were enriched and determined in body fluids such as urine [144-146, 167-172] or blood [147, 156, 157, 173, 174]. A very advanced apphcation of SLM for analytical purposes, where transport process was based on simple diffusion with pH adjustment of aqueous phase, is the extraction of the basic drug, bambuterol, for pretreatment of plasma samples before analysis with capfflary zone electrophoresis (CZE) [147]. Bambuterol was used as a model substance in a separation system, where either 6-undecanone or a mixture of di- -hexyl ether (DHE) and tri- -octylphosphine oxide (TOPO) was used as membrane phase. It was possible not only to achieve a very low hmit of detection ( 50 nmol/1) but also to ensure the removal of salts from the sample. It helped to obtain the low ionic strength of the blood plasma samples and permitted subsequent sample stacking in the caphlary electrophoresis step. 

In the case of industrial wastewater, several other compounds can also be involved, such as sulphide, hexavalent chromium or organic molecules. This last group of compounds is considered hereafter with regard to their economic and/or environmental importance. For example, Fig. 5 presents several specific compounds encountered in refinery and petrochemical wastewater. Thus, phenol, EPA (ethylpropylacrolein), TBC (tertiobutylcatechol), NMP (/V-methylpyrolidone) and nitrite can be detected in effluents or process water [21], Moreover, the estimation of complementary aggregate parameters, such as total oxygen demand (TOD), is possible from the estimation of one of the previous organic compounds [3] (Fig. 6). 

Nyokong, T. (2006) Electrodes modified with monomeric M-N< catalysts for the detection of environmentally important molecules, in N4-Macrocyclic Metal Complexes Electrocatalysis,... 

In this section we review the use of metal oxide semiconductor gas sensors for the detection of environmentally important gases such as carbon monoxide, carbon dioxide, ammonia and nitrous oxides. 

Polychlorinated biphenyls, used mainly in transformer oil, are environmentally important due to their suspected toxicity. Ritchie et al. used an IMS detector in the negative polarity to determine PCB isomers (congeners) having five or more chlorine atoms at detection levels of 35 ng by extracting them into an iso-octane solution. Mixtures of up to four PCB congeners showed characteristic multiple peaks. 

For trace analysis, the main ceramic elements of interest are Zn, Pb, Cu, Bi, Sb, Sn, Ag, As, Mn, Cr, Se, and Hg. Many of these are environmentally important. In certain cases the detection limits of flame AAS are inadequate, so that hydride generation for antimony, selenium, arsenic and bismuth, cold vapor for mercury, and graphite furnace AAS for lead and cadmium are required. A variation of AAS is atomic fluorescence, and this is used to achieve the detection limits needed for Hg and Se in environmental samples. Microwave digestion techniques for sample preparation are becoming more common, where, unlike fusion, there is no risk of loss of volatile elements from unfired samples and fewer reagents are... 

Such a variety of compounds requires the application of the full panoply of analytical techniques including ELISA, LC, LC-MS, GC-MS (negative and positive ion), GC-MS-MS. Newer methods may include online SPE systems combined with MS or UV or electrochemical detection systems. One important consideration is that analysis of a particular EDC should also include its degradation and/or metabolic products because these too may remain active. So for alkyl phenols the concurrent measurement of the appropriate alkyl phenol ethoxylates and alkyl phenoxycarboxylic acids is environmentally important and a significant analytical challenge. 

Abstract The development of electrochemiluminescence (ECL) applications is a growing field, having the potential advantages of ECL over conventional chemiluminescence. ECL has found various applications in immunoassays, DNA probe assays, and aptasensors by employing ECL-active species as labels on biological molecules. The recent use of ECL to detect many chemically, biochemically, clinically, and environmentally important analytes is reviewed. 

GC/FTIR data have also contributed to the structure elucidation of other compounds of biological origin, such as mycotoxins, which are formed by fungal activity in food products under specific environmental conditions of moisture, temperature, and host. Trichothecene mycotoxins, secondary fungal metabolites produced by species of mold, are a natural contaminant of feedstuffs and food. Because they can be toxic to humans and animals, their detection is important. Sehat et al., utilized GC/MI-FTIR and GC/MS to analyze grains for these contaminants. 

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