Organic acids comparing sample preparation

DCP-AES can be used for high-viscosity matrices, slurries, etc. Organic solvents and acids can be handled without problems. Sample preparation is simpler than for ICP. Operating costs are much lower than for ICP-AES. Table 8.32 compares DCP-AES to ICP-AES and FAAS Table 8.33 shows typical detection limits. DCP and its applications were reviewed [208]. 

Triprolidine hydrochloride in syrups and tablets can be analyzed by fluorimetry. A portion of the tablets or syrup is made basic with IN NaOH and extracted with ethylene chloride. The organic phase is then extracted with 0.1N I SO. The fluorescence of the acid extract is determined with a fluorometer using a UG11 filter for excitation and a Wratten 2A filter for emission. The fluorescence of the sample preparation is compared against a Reference Standard prepared in the same manner22. 

A wet oxidation procedure which utilizes sulfuric, nitric, and perchloric acid was established as a satisfactory method for destroying the organic matrix of petroleum samples with quantitative retention of the arsenic. Table 5.1 compares the amount of arsenic added to three petroleum samples with the amount of arsenic found on analysis by the method subsequently adopted. In each case the amount found by analysis agrees with the amount added within the precision of the method and indicates that the arsenic is quantitatively retained by the sample preparation procedure. Quantitative retention of the arsenic was further substantiated by neutron activation analysis of a sample which was spiked with a known amount of triphenylarsine. The arsenic concentration was determined at each step of the sample preparation procedure (Table 5., II). The results were in general agreement with the amount added and confirmed the earlier conclusion that arsenic is quantitatively retained during sample preparation. 

Several papers investigated the use of SPME for VFA analysis in wastewater and in air. Briefly, a fiber is exposed to the sample headspace or inserted directly into the sample. Analytes adsorb onto the fiber and are subsequently desorbed at high temperatures in the GC injection port. SPME is a solvent-free technique which introduces less potential contaminants into the GC compared to direct injections. SPME is also rapid since no further sample preparation steps are required. It may be used for routine analysis provided that the specific autosampler required for this method is available and that the optimized method conditions are suitable for autosampler application. Further information on principles and other applications of this technique can be found elsewhere. " " Parameters which have been optimized for VFA analysis are fiber coating, fiber exposure time, sample temperature, sample pH, sample agitation, potential salt addition, and desorption parameters. Surrogate standards employed for VFA analysis were 2-ethylbutyric acids for GC/FID or GC/MS and C-labeled organic acids for GC/MS. The method was optimized using standards in deionized water and only a few wastewater samples were analyzed as examples. 

The weakly nitric-acid solution obtained as a result of concentration of the water sample is extracted with ethyl acetate following the addition of aluminium nitrate. The organic phase containing the uranium is separated off, evaporated in a platinum crucible, and the uranium is melted at 630 °C after adding sodium fluoride/potassium carbonate/sodium carbonate as a fluxing agent. The yellow-green fluorescence of the melt which appears when irradiated with an ultraviolet lamp is compared with that of standard samples prepared under equivalent conditions. 

IR and Raman spectroscopy are common tools to study organic compounds like. The methods are rapid, non-destructive and with no need for sample preparation [78]. There is a considerable number of experimental studies using IR spectroscopy to characterise PBI-type polymers doped with phosphoric acid [7-9, 60, 61, 74, 79, 80]. The number of Raman studies is still limited, despite the fact that the intensity of vibration modes from polymer skeleton are enhanced compared to N-H and O-H vibration modes, i.e. there are less interferences due to the presence of water. 

Acetic acid is a reasonable solvent which doesn t cause interferences. Its solvent strength for PAH is comparable to the low boiling chlorinated hydrocarborts. An important disadvantage of acetic acid is the formation of salts from the mineral part of the fly ash. After evaporation of the solvent a salt residue remains, which has to be isolated from the organic part by water extraction. Since it is unsuitable to have too many steps of sample preparation in trace analysis, extraction with acetic acid is not recommended. It was fotmd that water is contaminated with PAH in a way that it might affect the determination without further puriftcation by preextraction. 

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