Abstract
BackgroundA complexometric method based on selective masking and de-masking has been developed for the rapid determination of aluminium, lead and zinc from the same solution in glass and glass frit samples. The determination is carried out using potassium cyanide to mask zinc, and excess disodium salt of EDTA to mask lead and aluminium. The excess EDTA was titrated with standard Mn(II)SO4 solution using Erichrome Black-T as the indicator. Subsequently selective de-masking agents – triethanolamine, 2,3-dimercaptopropanol and a formaldehyde/acetone mixture – were used to determine quantities of aluminium, lead and zinc in a stepwise and selective manner.ResultsThe accuracy of the method was established by analysing glass certified reference material NBS 1412. The standard deviation of the measurements, calculated by analysing five replicates of each sample, was found to be less than 1.5% for the method proposed.ConclusionThe novelty of the method lies in its simplicity and accuracy afforded by there not being a need for a prior separation or instrumentation. The proposed method was found to be highly selective for the precise determination of aluminum, zinc and lead in the routine analysis of glass batch and allied materials.
Highlights
A complexometric method based on selective masking and de-masking has been developed for the rapid determination of aluminium, lead and zinc from the same solution in glass and glass frit samples
For the selective demasking of aluminium, we employed triethanolamine, which reacts with iron
In general glass frit samples contain small quantities of magnesium, which form Mg-EDTA complexes and may react with manganese releasing the magnesium ion, causing difficulty in the end point detection. This type of replacement reaction occurs at higher temperatures, EDTA complexes of Ca and Mg remains in solution without interfering and for this reason it is necessary to carry out the reaction at low temperatures
Summary
A complexometric method based on selective masking and de-masking has been developed for the rapid determination of aluminium, lead and zinc from the same solution in glass and glass frit samples. The determination is carried out using potassium cyanide to mask zinc, and excess disodium salt of EDTA to mask lead and aluminium. The composition of glass and glass frits dictates their applications, with physico-chemical properties like optical, thermal expansion, electrical, flow ability and chemical resistance varying [1]. Aluminium and zinc are often present together in optical glasses and low melting glass frits [3]. Thermal and electrical properties of glass and glass frit [4,5]
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