Atomic absorption spectroscopy metal complexes

Atomic absorption spectroscopy metal complexes biology, 550 ATP synthesis... 

Metal impurities can be determined qualitatively and quantitatively by atomic absorption spectroscopy and the required purification procedures can be formulated. Metal impurities in organic compounds are usually in the form of ionic salts or complexes with organic compounds and very rarely in the form of free metal. If they are present in the latter form then they can be removed by crystallising the organic compound (whereby the insoluble metal can be removed by filtration), or by distillation in which case the metal remains behind with the residue in the distilling flask. If the impurities are in the ionic or complex forms, then extraction of the organic compound in a suitable organic solvent with aqueous acidic or alkaline solutions will reduce their concentration to acceptable levels. 

Discussion. Because of the specific nature of atomic absorption spectroscopy (AAS) as a measuring technique, non-selective reagents such as ammonium pyrollidine dithiocarbamate (APDC) may be used for the liquid-liquid extraction of metal ions. Complexes formed with APDC are soluble in a number of ketones such as methyl isobutyl ketone which is a recommended solvent for use in atomic absorption and allows a concentration factor of ten times. The experiment described illustrates the use of APDC as a general extracting reagent for heavy metal ions. 

Many of the reactions described above are seen to give less than quantitative recovery of the rhodium catalyst component. The amount of rhodium remaining in a catalyst solution was determined by atomic absorption spectroscopy, and is reported as the percent of the rhodium charged which remains soluble or suspended in the reaction mixture at the end of the reaction (95). After some experiments a wash procedure was employed to dissolve rhodium complexes possibly left in the reactor heating a charge of pure solvent in the reactor under H2/CO pressure sometimes dissolved substantial amounts of rhodium species (94-96, 104, 108, 109). High recoveries of rhodium are essential in a practical process because of the scarcity and high price of this metal (120, 121). 

Maintaining the quality of food is a far more complex problem than the quality assurance of non-food products. Analytical methods are an indispensable monitoring tool for controlling levels of substances essential for health and also of toxic substances, including heavy metals. The usual techniques for detecting elements in food are flame atomic absorption spectroscopy (FAAS), graphite furnace atomic absorption spectrometry (GF AAS), hydride generation atomic absorption spectrometry (HG AAS), cold vapour atomic absorption spectrometry (CV AAS), inductively coupled plasma atomic emission spectrometry (ICP AES), inductively coupled plasma mass spectrometry (ICP MS) and neutron activation analysis (NAA). 

Copper-containing molecular sieve materials are very important catalysts in many liquid-phase oxidation reactions. The analysis of metal content is usually obtained using atomic absorption spectroscopy (AAS) but this provides no information on the distribution of the metal within the material. In this paper, we report on the characterisation of a siliceous MCM 41 material postmodified with a Schiff base copper complex by x-ray photoelectron spectroscopy (XPS), AAS and other standard techniques. Quantitative estimations of the copper concentrations and chemical states and its distribution within the material have been made using XPS. The effect of modification by the Schiflf base copper complex on the surface characteristics of the MCM 41 was investigated by nitrogen sorption at 77 K. 

Two further analytical methods are based on the formation of metal complexes. Reaction of dopamine with KzCrjOy gives a Cr complex which can be assayed by atomic absorption spectroscopy, carbon rod absorption spectroscopy or, if Kf CrjO has been used, by liquid scintillation spectroscopy. Since the complex still gives a reaction with fluorescamine, the side-chain is thought not to be involved in the formation of the complex. Methamphetamine hydrochloride can be precipitated as a Bi complex. Determination of the amount of Bi remaining in solution by atomic absorption spectroscopy provides an indirect method of assay for the amphetamine. ... 

Volatile complexes of organic compounds of metals are, however, used more widely in GC analysis [45, 46, 211]. The main adwmti e of the GC analysis of volatile compounds of metals is the possibility of analysing trace amounts of metals with the use of ECDs and microwave emission detectors. When detectors of this type were used, GC methods were compared with such methods as neutron-activation analysis and atomic-absorption spectroscopy. The field of apphcation for this method is indicated in Table 1.5, illustrating the analysis of trace amounts of elements in the form of volatile complexes and compiled from data pubUshed in the literature. 

The general results obtained with the present polymerization systems may be summarized as follows, (i) terpyridyl-based monoligated systems may be used in ATRP. Generally, the use of monoligated initiators results in comparably fast polymerizations, (ii) Complexes that contain the reduced species of the corresponding metal (preferably Cu) were found to work best and additionally avoid the use of a reducing agent (e. g. MAO, Al(/-OPr)3). (iii) poly (styrene) may be prepared up to a of 80,000 in 20 - 30 % yield. Polydispersities vary from 1.5 - 1.9. These polymers are virtually metal free as determined by atom absorption spectroscopy (AAS, metal content < 100 ng/g). (v) Polymerizations proceed fast, yet level off after approximately 2 hours at monomer consumption < 30 %. In principle, polymerization may cease due to deactivation or recombination of the radicals. Based on the fact that polymerization yields are neither influenced by the addition of further initiator... 

Atomic absorption spectrometry (AAS) has been used to determine cationic and anionic surfactants indirectly. Two methods have been put forward based on the formation of the ion pair between surfactant and hexanitrocobaltate (for cationic compounds) or bis(benzoyl)pyridine thiosemicarbazone cobalt (III) (for anionic compounds). In the former case, the complex is extracted with 1,3-dicloroethane and in the latter with an isopentylacetate and isopentyl alcohol mixture. Concentration of cobalt is determined in the organic phase using electrothermal atomic absorption spectroscopy (ETAAS), while for anionic surfactants, flame atomic absorption spectroscopy (FAAS) can also be used. Interferences like metal ions, anions and organic compounds do not have a great relevance. The two methods were applied to determine dodecyltrimethylammonium bromide in shampoos (Chattaraj and Das, 1992) and sodium lauryl sulfate (SDS) in toothpastes (Chattaraj and Das, 1994). 

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