Pál Halmos

Sample preparation procedure for the determination of sulphur and trace metals in oil products by the ICP with a minitorch using emulsions

A quick sample preparation method was used for the determination of sulphur and trace metals in oil and oily products by the ICP with a minitorch. Stable aqueous emulsions of oils and oil products were made by using two kinds of emulsifiers (one with low sulphur content, the other sulfonated). Aqueous standard solutions can be used for the preparation of calibration solutions. The contents of S, Al, Cr, Cu, Fe, Mg, Ni and Pb in aqueous emulsions were determined and the results were in good agreement with the composition of oil standard solutions used for control analysis procedure.

Preparation and chemical characterization of high purity fluorapatite

High purity fluorapatite (FAP) was prepared by solid state reaction, in flowing argon gas, at 1370 degrees C for 60 min. For chemical characterization of Ca(10)(PO(4))(6)F(2), the accuracy and reproducibility of different analytical methods were assessed. Methods with a good accuracy for the determination of Ca, P and F content were: titrations with EDTA for Ca determination (accuracy: -0.8%), spectrophotometric method for P determination (accuracy: +0.6%) and measurements with fluoride-selective electrode (accuracy +5.4%) for F determination.

Determination of sulfur content of diesel fuels and diesel fuel-like fractions of waste polymer cracking

The element content of low and high sulfur containing diesel fuels was measured by different analytical methods: energy-dispersive X-ray fluorescent (EDXRF) and inductively coupled plasma atomic emission (ICP-OES) spectroscopy methods. Then results were compared. High sulfur containing diesel fuels were from heavy diesel engines and diesel fuel-like liquids obtained by thermal degradation of waste polymers. In case of X-ray analysis also the effect of the used thin foils with different chemical compositions (polypropylene, polycarbonate, polyester) on the accuracy was investigated. According to data considerable differences and deterioration of accuracy was observed in the respect of foils in case of both low and high sulfur containing hydrocarbons. Results indicated appropriate correlation between experimental results measured by both two methods, but differences could be observed in the correlation, which could be explained with different ratio of C/H of samples.

Trace elements in clinker: II. Qualitative identification by fuzzy clustering

The trace element content of clinkers (and possibly of cements) can be used for the qualitative identification (i.e., manufacturing factory). This paper proposes a fuzzy classifier for the discrimination of clinkers produced in different factories based on their Mg, Sr, Ba, Mn, Ti, Zr, Zn and V content. The fuzzy classifier is identified by unsupervised fuzzy clustering. The most relevant trace elements were selected based on the obtained clusters by the modified version of the Fisher interclass separability method. The classification of a country from the European Community and South African clinkers is used as an illustrative example. The results show that the proposed method is useful to identify compact classifiers that are able to determine the origin of the clinker; the obtained classifier is easy to use and interpret for engineers and researchers, even when they are not familiar with the concept of fuzzy logic.

The use of outer-sphere complex formation reactions in ion-exchange chromatography: Separation of maleate and fumarate ions

Outer-sphere complex formation reactions have been used to increase the selectivity of ion-exchange separation of maleate and fumarate ions. The stability constants of the maleate and fumarate complexes of tris(ethylenediamine)cobalt(III) and hexa-amminecobalt(III) have been determined at different ionic strengths from the elution volumes and the parameters of the ion-exchanger bed, and the values at I = 0 obtained by extrapolation. They are: log K [Co(en)(3+)(3) + Ma(2-)] = 3.33; log K [Co(NH(3))(3+)(6) + Ma(2-)] = 3.77; log K [Co(en)(3+)(3) + Fu(2-)] = 1.19; log K [Co(NH(3))(3+)(6) + Fu(2-)] = 1.99. The two anions can be separated quantitatively.

Application of pressurized sample preparation methods for the analysis of steels and copper alloys

Pressurized sample preparation devices (High Pressure Asher, Pressurized Microwave Digestion system, compared with a PTFE decomposition vessel) were used to dissolve certified metal alloy samples (steel, copper) for ICP analysis. Based on the results of the analysis it was established that both up-to-date devices can be advantageously applied to quickly and quantitatively dissolve metal alloy samples. To dissolve the samples, two different kinds of acid mixtures (A: nitric and hydrochloric acid; B: nitric and hydrochloric and sulphuric and phosphoric acid) were used. The sample preparation is simpler and less time-consuming than the earlier commonly used methods, sample loss and degree of contamination are also reduced. Steel samples containing tungsten, titanium and niobium (less than 0.5%) can only be analyzed using a mixture of the four acids. By dissolving steel samples in the nitric and hydrochloric acid mixture, the concentration of their most common elements (Cr, Ni, Mn, V, Cu) as well as their S and P content can be determined. Copper alloy samples can be dissolved quickly by the pressurized microwave decomposition device using hydrochloric acid and diluted (1:1) nitric acid.

Automated indirect fluoride determination by ICP-OES using discontinuous-flow analysis.

An automated method for the indirect determination of fluoride by inductively coupled plasma atomic emission spectrometry using discontinuous-flow analysis has been developed. A modified flow injection analysis system was used for sample preparation. The method is based on the determination of excess cerium(III) ion after precipitation of CeF3. Separation of the precipitate is performed online on a syringe membrane filter that is cleaned each analysis cycle by 1 M nitric acid, ensuring a long life-time for the filter. As a result of the short reaction time, a detection limit of 9.5 mg L−1 was obtained. The precision (RSD) of the proposed method is 1.02% at fluoride concentration of 28 mg L−1. The applicability of the technique for groundwater monitoring of fluoride-contaminated area is demonstrated.