The production of glasses and glass frits has considerably increased in recent decades owing to expansion of such materials' applications in modern science and technology. 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 . In general the major to minor constituents in glass frit and glass are respectively: SiO2, Na2O, Al2O3, PbO, TiO2, ZnO, MgO, BaO, B2O3, F, CaO, and ZrO2 ; while the trace elements like Cd, Co, Ni, Fe, Mn, Sn, Cr are sometimes found to be present, when employed in certain applications . Lead, aluminium and zinc are often present together in optical glasses and low melting glass frits . Lead bearing glasses possess low softening points and are used to join one glass to another or a metal to a glass frit . The function of aluminium in frits is to reduce atmospheric moisture attack in an acidic environment and increase the viscosity and softening point of the frit. Zinc enhances the optical, thermal and electrical properties of glass and glass frit [4, 5].
Complexometry is a very useful method for the determination of major quantities of metals present in various combinations. The literature shows that analyses of such materials are based on separation, which is laborious and time consuming [6–9]. The conventional methods for the determination of aluminium, zinc and lead are based on complexometry using EDTA [6, 7], colorimetry  or polarographic approaches . In all these procedures the quantity of the element is determined individually using separate aliquots with the interfering elements in some cases being separated. Dasgupta et al [10, 11] described another method, based on gravimetric, complexometric and instrumental techniques, which proved to be complex and lengthy. More recently several workers have reported different methods [12–16] for the determination of these elements in glass and allied materials by inductively coupled plasma atomic emission spectroscopy (ICP-AES) and atomic absorption spectroscopy (AAS) [13–16]. Undoubtedly ICP-AES and AAS are the preferred methods although the relevant instrumentation is costly. When using such instruments the elements either need to be separated, extracted or masked from other interfering elements. Several instrumental parameters must be controlled. Therefore rapid and precise determination of aluminum, zinc and lead in the same solution by complexometric method is a challenge as a regards quality control.
In the complexometric titrations, masking and demasking agents have been used from past decades. Pribil and his coworkers demonstrated wide applications of using more than one masking agent and combined masking and demasking agents in complexometric methods [17, 18] for large quantities of cations when present together. Potassium cyanide is an effective masking agent for large quantities of cations; similarly triethanolamine and 2,3 dimercaptopropanol have been employed in several studies [17–20].
In light of these previous studies, we have attempted to determine the quantities of aluminium, zinc and lead in the same solution in a selective and quantitative way by masking zinc with potassium cyanide, aluminium and lead with EDTA, and then de-masking the respective complexes using a formaldehyde:acetone mixture, triethanolamine and 2,3-dimercaptopropanol. The process is simple, accurate and does not require separation and extraction or costly instrumentation.