Principles and Problems of Cadmium Analysis
Lars Friberg, Tord Kjellström, Carl-Gustaf Elinder, Gunnar F. Nordberg in Cadmium and Health: A Toxicological and Epidemiological Appraisal, 2019
Normally, biological samples have to be digested (destructed) in order to separate cadmium from the organic matrix before analysis. Common methods to destroy and oxidize organic matrixes are wet and dry ashing. In dry ashing, the sample is oxidized by air or oxygen at a relatively high temperature, usually between 400 and 500°C in a muffle furnace, for more than 12 hr. Dry ashing should result in the complete ashing of the samples. The ashes are subsequently dissolved in nitric acid or some other solvent. Low temperature dry ashing at about 100°C can be performed in a plasma asher, containing a high concentration of oxygen. During low temperature ashing, the risk of loss due to volatilization is minimal.21,48 The problem of loss of cadmium during ashing at temperatures below 500°C is also as a rule minimal.37,45,61 In a study of the recovery of 109Cd added to wheat samples, no measurable losses occurred when ashing was carried out at 450°C.35
Glycerine Analysis
Eric Jungermann, Norman O.V. Sonntag in Glycerine, 2018
The most common method for measuring arsenic content uses silver diethyl-dithiocarbamate as a colorimetric reagent. Food Chemical Codex and USP require wet-ashing the sample before the colorimetric analysis is performed. CTFA specifies diluting the sample without wet-ashing and proceeding directly to the color-generating step. Wet-ashing destroys organic matter and converts arsenic to the arsenic (V) oxidation state without loss of volatile arsenic compounds, which would occur if the sample were ashed at muffle oven temperatures. About 1 g of glycerine is digested with sulfuric acid until charring begins. Thirty percent hydrogen peroxide is added, very slowly and carefully at first, to prevent too violent a reaction. Oxidizing conditions are maintained by adding more peroxide whenever the solution becomes dark. When oxidation is complete, the temperature is increased until copious fumes of SO3 evolve. Then, the sample is cooled, water is added and the solution is fumed again to remove traces of hydrogen peroxide.
Analysis of Clinical Specimens Using Inductively Coupled Plasma Mass Spectrometry
Steven H. Y. Wong, Iraving Sunshine in Handbook of Analytical Therapeutic Drug Monitoring and Toxicology, 2017
Regulations and public pressure are forcing more and more employers to screen employees exposed in the work environment; therefore, it is not surprising that the number of tests requested (e.g., whole blood lead analysis) is rapidly increasing.56 Consequently, there is a need for easy specimen collection and handling for this kind of screening tests. One of the current trends is sample collection on filter paper.57–59 In our laboratory, a reproducible portion of the filter paper containing the specimen is placed in an ethylenediamine tetroacetic acid (EDTA) solution to remove the metal ion(s) of interest. Because no wet ashing is necessary, the handling of hazardous concentrated acid is avoided.
Gamma irradiations induced morphological and biochemical variations in in vitro regenerated ginger (Zingiber officinale rosc.)- an invaluable medicinal spice
Published in International Journal of Radiation Biology, 2021
Crude fiber consists largely of cellulose, lignin (97%) and mineral matter. High contents of ginger fiber make it unsuitable for processing purposes. For crude fiber estimation, the residue obtained after oleoresin extraction was used. 2 gm of extracted sample was digested in 200 ml of sulfuric acid for 30 min, filtered through muslin cloth and washed with boiling water until washings were no longer acidic. After that, residue was digested with 200 ml NaOH for 30 min, again filtered through muslin cloth and washed with 25 ml of boiling 1.25% H2SO4 + 50 ml portion of water + 25 ml alcohol. Residue was removed and transferred to preweighed ashing dish and dried for 2 hours at 130 ± 2 °C. Ashing dish was cooled down and ignited for 30 mins at 600 ± 15 °C in muffle furnace. Finally the weight ashing dish was measured to calculate crude fiber content (Rana et al. 2004c).
Health risk assessment of heavy metals content in cocoa and chocolate products sold in Saudi Arabia
Published in Toxin Reviews, 2019
Samples were oven dried at 100 °C for 48 h and ground to fine powder in a porcelain mortar and were placed in a muffle furnace for dry ashing. Three dried samples (6 g, each) with three replicates for each item were placed in crucibles and some drops of analytical grade nitric acid were added as an ashing aid. Ashing process was carried out in a muffle furnace by stepwise increase of the temperature up to 550 °C and then left to ash at this temperature for 4 h (Crosby 1979). The resultant ash was left to cool and then rinsed with 1 M nitric acid. The ash suspension was filtered into a 25-mL volumetric flask and the solution was made up to mark with nitric acid (1 M).
Effects of polymerised whey protein-based microencapsulation on survivability of Lactobacillus acidophilus LA-5 and physiochemical properties of yoghurt
Published in Journal of Microencapsulation, 2018
Mu Wang, Cuina Wang, Fen Gao, Mingruo Guo
Cow and goat milk yoghurt samples were determined for total solids, protein, fat, ash, and carbohydrate contents. Total solids content was determined by a moisture metre (MJ33, Mettler Toledo, Zurich, Switzerland). Protein content was measured by Kieldahl Azotometer (UDK-159, VELP Scientific Co., Ltd, Brianza, Italy) using a conversion factor of 6.38. Fat content was measured by Gabriel centrifugation method (5 min, 110 × g). Ash content was measured by dry-ashing using a muffle furnace (SX-2.5–12, Jingke, Shanghai, China). Carbohydrate content was calculated by the content of total solids minus protein content, fat content and ash content.
Related Knowledge Centers
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