Leather. Determination of water-soluble magnesium salts. EDTA titrimetric method

2015 ◽  
1968 ◽  
Vol 51 (5) ◽  
pp. 963-967 ◽  
Author(s):  
R H Abaza ◽  
J T Blake ◽  
E J Fisher

Abstract Accurate quantitative determination of oxalate in chemical analyses of edible plants is important because oxalate is a poisonous compound. The traditional KMn04-oxalate reduction-oxidation (Dye) method of analyzing for plant oxalate content presents two problems: (a) Plant pectins are not entirely separated in the determination of watersoluble oxalate and interfere in the oxidation of oxalate; and (b) a brownish-black precipitate containing ferrous iron is precipitated at the same pH as calcium oxalate and the precipitate interferes in determination of both water- and acid-soluble oxalate. Our modification of the Dye method consists of (a) using double-distilled water as the diluting medium, (6) increasing the acidity of the water-soluble oxalate medium after plant digestion to obtain complete removal of pectins, and (c) eliminating the ferrous iron-containing precipitate by filtration. Oxalate in the ferrous iron-containing precipitate is determined as calcium and magnesium salts by atomic absorption spectrophotometry; the value thus obtained is added to the oxalate value from the oxidation- reduction method. An indirect analytic method for oxalate, in which all of the oxalate was precipitated as the calcium salt and then measured by atomic absorption spectrophotometry, proved to be inaccurate


Author(s):  
Hind Hadi ◽  
Gufran Salim

A simple, rapid and sensitive spectrophotmetric method for trace determination of salbutamol (SAL) in aqueous solution and in pharmaceutical preparations is described. The method is based on the diazotization coupling reaction of the intended compound with 4-amino benzoic acid (ABA) in alkaline medium to form an intense orange, water soluble dye that is stable and shows maximum absorption at 410 nm. A graph of absorbance versus concentration indicates that Beer’s law is obeyed over the concentration range of 0.5-30 ppm, with a molar absorbtivity 3.76×104 L.mol-1 .cm-1 depending on the concentration of SAL. The optimum conditions and stability of the colored product have been investigated and the method was applied successfully to the determination of SAL in dosage forms.


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