Microwave Acid Digestion for the Determination of Metals in Subbitumnious Coal Bottom Ash by ICP-OES

The focus of most lubricating grease testing has been based on performance and appearance rather than determining the concentration of chemical components. The primary reason being lubricating grease is a difficult matrix to work with from the perspective of the analytical laboratory. The purpose of this study was to develop a simple, reproducible method for elemental determination in lubricating grease and to apply the developed method to work out a flushing procedure for the filling lines in a grease manufacturing plant. The first part of the experimental work focused on developing a suitable and efficient sample preparation technique. Three techniques were explored: direct dilution, microwave assisted acid digestion and emulsification. Direct dilution involved shear mixing the lubricating grease with metal free base oil and diluting it with an organic solvent. Use of these solvents caused plasma destabilization or even plasma extinction and their use posed health risks for laboratory personnel. Microwave digestion involved mineralising the lubricating grease using an optimised microwave assisted acid digestion procedure. In the third sample preparation technique, microemulsions were formed by mixing the lubricating grease with a relatively small volume of a strong mineral acid mixture followed by the surfactant (triton X-100) at room temperature and pressure (RTP). This approach does not require the destruction of the organic matter or the use of large amounts of organic solvents. For all three techniques the sample was subsequently analysed for Al, B, Ba, Ca, Li, Na, S, Mo and Zn. All analysis was performed using an Optima ICP-OES with previously optimised parameters. The direct dilution method gave the most inconsistent results with relative standard deviation (RSD) as high as 56% for calcium, 79% for boron and 66% for lithium. Microwave digestion and emulsification gave comparable results, with the calibration curves of oil emulsions not differing significantly from aqueous ones. For microwave assisted acid digestion the limits of detection ranged from 0.028 mg/L for sodium to 0.255 mg/L for boron. Correlation coefficient values (r2) of all the elements were greater than 0.99. Likewise the limits of detection for emulsification ranged from 0.03 mg/L for aluminium to 0.37 mg/L for sulphur. The correlation coefficients for all the elements were greater than 0.99 and this indicates that the calibration curves were sufficient for analysing the digested grease samples. Five quality assurance samples were analysed using both methods and in addition a t-test performed at the 99.9% confidence level and 4 degrees of freedom showed that the two sample preparation techniques gave similar results. Emulsification has several advantages over microwave digestion technique and superior analytical performance over direct sample dilution using solvents, and hence was chosen as the method of choice for routine analysis of lubricating grease. The second part of the experimental work focused on developing a flushing procedure for filling lines in a lubricating grease plant. A flushing procedure is essential in order to minimise waste, which will in turn minimise production costs and avoids incurring disposal costs. In this series of experiments, the microwave digestion sample preparation technique was utilised for the subsequent determination of the flushing mass required in between product changes. The flushing procedure was implemented and monitored by the use of statistical quality control tools for a specified period of time, and as indicated by Shewart Control charts, the process was in statistical control.

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An Inductively Coupled Plasma Optical Emission Spectrometric Method for the Determination of Toxic and Nutrient Metals in Spices after Pressure-Assisted Digestion

Applied Sciences ◽

10.3390/app12020534 ◽

2022 ◽

Vol 12 (2) ◽

pp. 534

Author(s):

Natalia Manousi ◽

Eleni Isaakidou ◽

George A. Zachariadis

Keyword(s):

Inductively Coupled Plasma ◽

Optical Emission ◽

Good Method ◽

Black Pepper ◽

Spectrometric Method ◽

Icp Oes ◽

Acid Digestion ◽

Green Pepper ◽

Inductively Coupled

The aim of this study was to develop a simple and rapid inductively coupled plasma optical emission spectrometric (ICP-OES) method for the determination of 17 metals (Ag, Al, B, Ba, Bi, Ca, Cd, Co, Cr, Cu, Fe, Mg, Mn, Ni, Pb, Tl and Zn) in packaged spices. For this purpose, the spice samples (200 mg) in the form of powder were submitted to pressure-assisted wet-acid digestion with a mixture of 6 mL concentrated HNO3 and 1 mL H2O2. The proposed method was validated in terms of linearity, trueness, precision, limits of detection (LODs) and limits of quantification (LOQs). Good method trueness, precision and linearity were observed for the examined elements. The LODs of the examined analytes ranged between 0.08 and 5.95 mg kg−1. The present method was employed for the analysis of twenty-two packaged commercially available spices including asteroid anise, clove, cardamon, cinnamon, curry, coriander, turmeric, cumin, white pepper, black pepper, nutmeg, allspice, red pepper, paprika, ginger, green pepper and pink pepper from the Greek market that are widely consumed. A wide variety of metal of different concentration ranges were determined in the samples.

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Determination of Major, Minor, and Toxic Elements in Tropical Fruits by ICP-OES After Different Microwave Acid Digestion Methods

Food Analytical Methods ◽

10.1007/s12161-020-01884-3 ◽

2020 ◽

Author(s):

Ayca Karasakal

Keyword(s):

Toxic Elements ◽

Tropical Fruits ◽

Icp Oes ◽

Acid Digestion ◽

Digestion Methods

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Quantitative Determination of the Crystalline Phases of the Ceramic Materials Utilizing the Rietveld Method

Materials Science Forum ◽

10.4028/www.scientific.net/msf.660-661.164 ◽

2010 ◽

Vol 660-661 ◽

pp. 164-169 ◽

Cited By ~ 1

Author(s):

C.T. Kniess ◽

P.B. Prates ◽

J.C. de Lima ◽

N.C. Kuhnen ◽

Humberto Gracher Riella ◽

...

Keyword(s):

Quantitative Determination ◽

Rietveld Method ◽

Bottom Ash ◽

Ceramic Materials ◽

X Ray Diffraction ◽

Crystalline Phases ◽

Coal Bottom Ash ◽

Lattice Design ◽

Simplex Lattice

Ceramic materials have properties defined by their chemical and micro-structural composition. The quantification of the crystalline phases is a fundamental stage in the determination of the structure, properties and applications of a ceramic material. Within this context, this study aims is the quantitative determination of the crystalline phases of the ceramic materials developed with addition of mineral coal bottom ash, utilizing the X ray diffraction technique, through the method proposed by Rietveld. For the formulation of the ceramic mixtures a {3,3} simplex-lattice design was used, giving ten formulations of three components (two different types of clays and coal bottom ash). The crystalline phases identified in the ceramic materials after sintering at 1150oC during two hours are: quartz, tridimite, mullite and hematite. The proposed methodology utilizing the Rietveld method for the quantification relating to crystalline phases of the materials was shown to be adequate and efficient.

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