Synthesis of New azo-dye reagent and using to the spectrophotometric determination of Mercury ions in some cosmetics
A new spectrophotometric method has been described for the determination of mercury ions in some cosmetics. The method is based on the reaction of mercury ions with a new reagent. The new reagent was made by reacting diazonium [MCP] with (vitamin B6) to produce a new reagent called [5-chloro-N-(dimethylamino) ethyl]-4-(5-hydroxy-3,4-bis(hydroxymethyl)-6). -methyl pyridine-2-yl)diazeenyl)-2-methoxybenzamide] or it's called (BMAZ). The reagent was reacted with a trace amount of mercury ions at PH = 4 to give a pink solution.
The method was simple, rapid, sensitive, selective and accurate and the final orange solution showed maximum absorption at 548 nm.
Beers law was obeyed in the mercury ions concentration range of (0.75 – 6.5 ppm) with a molar absorptivity (1.18*10+5 L.mol-1.cm-1), and Sandell’s sensitivity (5.01*10-3 μg.cm-2). limit of detection (LOD) and limit of quantification (LOQ) are (0.004) ppm and (0.01) ppm, respectively. The dissociation degree (α) and the complex formation constant (Kf) were calculated and were respectively = (0.325, 2x107).
Charge of complex was determined via passing it on a positive(+) and negative(-) ion exchanger and found that the complex is( positively charged). It was found that the ions do not interfere when using this reagent because it is only selective for the two tons of zinc and mercury, and when studying the reagent with mercury, it was found that the reagent reacts with mercury at different conditions such as pH and solvent.
All of the optimum conditions of the method and the properties of the new reagent were studied such as pH of the reaction, the volume of the chemical reagents, and all other necessary conditions.
The method was applied to determine the trace amount of zinc ions in some drugs and the method shows accuracy with recovery percentage between (RSD %=0.42, E% = 1.14, Rec% = 101.14).