scholarly journals An improvement of calcium determination technique in the shell of molluscs

2009 ◽  
Vol 52 (1) ◽  
pp. 93-98 ◽  
Author(s):  
Cristiane Soído ◽  
Maurício Carvalho Vasconcellos ◽  
Antônia Gonçalves Diniz ◽  
Jairo Pinheiro
Keyword(s):  
Hydrogen Peroxide ◽  
Nitric Acid ◽  
Experimental Model ◽  
Calcium Content ◽  
Conventional Technique ◽  
Organic Substances ◽  
Complexometric Method ◽  
Wet Weight ◽  
Calcium Determination

The complexometric method is usually applied to quantitative calcium determination in different materials; however the application of this method to calcium determination in molluscs shells infers significant interferences to the results. The snail Bradybaena similaris, a terrestrial gastropod, was used as experimental model to the improvement of this method. The shells were calcinated and dissolved in nitric acid, the hydrogen peroxide was also used to clarify the medium after the acid addition. The calcination procedure and the use of nitric acid reduced the significantly the interferences, allowing a major degree of destruction of the organic substances of the shell. The improvement of the calcium determination technique usually employed showed calcium content of 874.24 ± 56.617 mg of CaCO3/g of ash in comparison to the conventional technique that allowed the determination of 607.79 ± 67.751 mg of CaCO3/g of shell, wet weight.

The Perchloric Method for the Determination of Sulfur in Rubber

1934 ◽  
Vol 7 (4) ◽  
pp. 730-735
Author(s):  
Ernest Kahane
Keyword(s):  
Nitric Acid ◽  
Perchloric Acid ◽  
Organic Substance ◽  
Present Author ◽  
General Idea ◽  
Organic Substances ◽  
Gutta Percha ◽  
Higher Temperature ◽  
As If

Abstract The problem of the determination of sulfur in rubber has been dealt with extensively in the literature, and it seems as if discussions and descriptions of new technic are nowhere nearly ended yet. The determination is so essential, and its rapid and precise execution is of such importance in industrial technic, that efforts in this direction should not be regarded as wasted. In 1926 and in 1927 Le Caoutchouc et La Gutta-Percha contained two articles in which the present author discussed the conditions of the determination of sulfur in rubber and then proposed the use of a new oxidizing mixture, not mentioned previous to that time, which involved the destruction of organic substances by perchloric acid. This method consisted simply in the attack on a 1-gram sample of rubber by 10 cc. of nitric acid (d. 1.39) and 5 cc. of perchloric acid (d. 1.61). Upon heating, attack by the nitric acid takes place, and this is followed by evaporation of the excess nitric acid, then at a little higher temperature there is an attack by the perchloric acid, which oxidizes the rest of the organic substance completely. This publication was concerned much more, in the determination of sulfur by the perchloric method, with the general idea of the destruction of organic substances than it was with the precise details of carrying it out. The technic had been studied somewhat superficially, as is shown by the text of the article itself.

Simplified Spectrophotometric Curcumin Method for the Determination of Boron in Marine Shellfish

1975 ◽  
Vol 32 (6) ◽  
pp. 813-816 ◽  
Author(s):  
R. E. Drew
Keyword(s):  
Hydrogen Peroxide ◽  
Standard Deviation ◽  
Acetic Anhydride ◽  
Sulphuric Acid ◽  
Relative Standard Deviation ◽  
Tissue Sample ◽  
Total Error ◽  
Relative Standard ◽  
Wet Weight

The method involves a sulphuric acid–hydrogen peroxide digestion of the tissue sample at 100 C, dehydration of the digest with acetic anhydride, formation of the boron–curcumin complex (rosocyanin), followed by buffering of the solution and measurement of the absorbance at 545 nm. Data are presented to show that a mean relative standard deviation of approximately 5% and a mean total error of approximately 12% can be expected for shellfish in the concentration range of 1.0–10.0 μg B/g wet weight tissue (ppm).

scholarly journals Preliminary Study for the Determination of Rare Earth Elements Using the ICP-MS Technique

2020 ◽  
Vol 71 (4) ◽  
pp. 277-288
Author(s):  
Gina Alina Catrina (Traistaru) ◽  
Gabriela Geanina Vasile ◽  
Ionut Nicolae Cristea ◽  
Georgiana Cernica ◽  
Cristina Ileana Covaliu ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Rare Earth ◽  
Nitric Acid ◽  
Rare Earth Elements ◽  
Aqua Regia ◽  
Calcination Process ◽  
Icp Ms ◽  
Different Temperatures ◽  
Digestion Methods

This paper proposes an optimized method for the determination of rare earth elements (Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) from soils using ICP-MS technique. First, the soil samples were thermal treated at three different temperatures 550ºC, 700ºC and 8500C in order to eliminate organic matter interferences. Then, the residual samples remaining from the calcination process were extracted in acidic medium with two different digestion methods (method I - a mixture of nitric acid and hydrogen peroxide; method II - aqua regia mixture) in order to quantify rare earth elements content. The highest recovery percentages for the major rare earth elements analyzed (Sc, Y, La, Ce, Pr, Nd. Sm) were situated in the range 86.13% to 99.90%, in sample residues thermally treated at 700�C and extracted with nitric acid and hydrogen peroxide.

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