Investigation of chemical modifiers for the determination of cadmium and chromium in fish oil and lipoid matrices using HR-CS GF AAS and a simple ‘dilute-and-shoot’ approach

The authors are grateful to the Conselho Nacional de Desenvolvimento Científico and Tecnológico (CNPq), and Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) for financial support and scholarships. The present research was mostly financed through Project no. CNPq 406877/2013-0. The authors are also grateful to Analytik Jena for financial support and the donation of the contrAA 600.Peer reviewedPostprin

Optimization of Microwave-Assisted Acid Digestion Method for Determination of Trace Elements in Coal and Coal Fly Ash

In most of the analytical and environmental laboratories today inductively coupled plasma (ICP) is a method of choice for analysis of trace metal elements present in coal and coal combustion products. This method requires use of liquid samples, so all coal and coal combustion products must be digested prior to analysis by ICP. Traditionally an open-air hot-plate acid digestion method published as ASTM D6357-04 was used to extract all trace metal elements into solution. Recent development of microwave systems designed for digestions under extreme acidic conditions and high temperatures and pressures shifted focus toward more rapid and precise microwave-assisted digestion of samples. A number of papers have been published involving research efforts toward development of quantitatively satisfying digestion methods. However, there is still no published ASTM or EPA method for microwave-assisted digestion of coal and coal combustion products. The goal of this research is compare the recoveries obtained by using hot plate method with results obtained by microwave-assisted digestion, as well as to attempt to optimize method conditions for latter

Separation and measurement of Pa, Th, and U isotopes in Marine sediments by microwave-assisted digestion and multiple collector inductively coupled plasma mass spectrometry

This manuscript describes a new protocol for determination of Pa/Th/U in marine sediments. It is based on microwave-assisted digestion and represents an important reduction of working time over conventional hot-plate digestion methods, and the use of HClO(4) is avoided. Although Th and U are completely dissolved with a first microwave step, around 40% of (231)Pa remains undissolved, and a short hot-plate step with reverse aqua regia is required to achieve total digestion and spike equilibration. Next, the method involves a separation of these elements and a further purification of the Pa fraction using Dowex AG1-X8 resin. Separation with Bio-Rad and Sigma-Aldrich resins was compared; although both perform similarly for Th and U, Pa yields are higher with Bio-Rad. Finally, samples are measured using a Nu instruments multiple collector inductively coupled plasma mass spectrometer (MC-ICPMS). Overall chemical yields range around 50% for Pa, 60% for Th, and 70% for U

Microwave-assisted digestion of ceramic frits for boron and lithium determination by inductively coupled plasma spectrometry (ICP-OES)

Boron and lithium are two elements commonly found in the chemical composition of ceramic frits. They are usually determined by volumetric titration and atomic absorption spectrometry, respectively, after melting the ceramic frit by high-temperature alkaline fusion and dissolving the melt in acid medium. This dissolution procedure is long and tedious, and does not enable determining both elements simultaneously. An alternative ceramic frit dissolution procedure based on microwave-assisted digestion in acid medium has been proposed, which allows jointly determining boron and lithium by inductively coupled plasma-optical emission spectrometry. This procedure is rapid and reproducible, and the results are independent of frit chemical composition

Digestão de óleo lubrificante encapsulado em forno de microondas com radiação focalizada por adição de amostra ao reagente pré-aquecido.

FOCUSED-MICROWAVE-ASSISTED DIGESTION OF ENCAPSULATED LUBRICATING OILS: GRADUAL SAMPLEADDITION TO PRE-HEATED ACID. The applicability of the recently proposed procedure based on gradual sample addition tomicrowave-assisted pre-heated concentrated acid is limited by the sample viscosity. In this work, lubricating oil samples with high viscositywere encapsulated and manually added to the microwave-assisted pre-heated concentrated digestion mixture. The procedure was appliedfor determination of Al, Ca, Cr, Cu, Fe, Mg, Ni, P, Pb, Si, Sn, Sr, V, W, and Zn in lubricating oil by inductively coupled plasma opticalemission spectrometry (ICP OES). Determined and certified values for Ca, Mg, P, and Zn in lubricating oil were in agreement at a 95% confidence level

Method development for the elemental analysis of organic rich soil samples by microwave plasma atomic emission spectrometry

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DETERMINATION OF SELENIUM IN SELECTED FOODS FROM NORTH MACEDONIA BY ETAAS FOLLOWED BY MICROWAVE-ASSISTED DIGESTION

For the determination of selenium in selected food products produced or purchased in North Macedonia, a suitable electrothermal atomic absorption method (ETAAS) was optimized and validated due to its biological activity and importance in human and animal nutrition. In this study, a sample preparation method with microwave digestion was used to digest various food samples for Se determination. The limit of detection (LOD) and limit of quantification (LOQ) were 0.99 µg/L and 3.30 µg/L, respectively. The validation results showed a recovery of 96.13-99.60%, and the relative standard deviation (RSD) was less than 5.3%. It was found that the determined selenium content was lower compared to the values reported from other Balkan countries. The highest Se content was found in protein-rich foods such as fish muscle of an endemic species of Lake Ohrid trout, then in pork, chicken breast and offal; the content in nuts, beans, milk and dairy products was average, while grain-based samples, fruits and vegetables had the lowest Se concentration

Simultaneous determination of major and minor constituents in cement and steel by inductively coupled plasma atomic emission spectrometry.

Methods for the simultaneous determination of major and minor constituents in cement and steel samples are developed in this thesis. The effect of matrix elements on analyte emission intensity has been evaluated. Dissolution procedures for these samples are based on the use of acids combined with a microwave-assisted digestion system and all measurements are then carried out by inductively coupled plasma atomic emission spectrometry. The previous methods of analysis for these samples has been reviewed. This section includes methods which are recommended by many authorities as Standard Procedures. It was found that the use of a microwave-assisted digestion system, coupled with inductively coupled plasma atomic emission spectrometry, reduced the total analysis time and reduced operating costs.The results obtained for the simultaneous elemental analysis of cement and steel using such methods are found to be in good agreement to the certified values. The methods developed offer the considerable advantages of rapid sample throughput, simplicity of use and are applicable for many routine analytical purposes