New reagent N, N,-N,-N - Tetramethyl-pe phenylenediamine dihydrochloride (TMPDA-2HCl) was described for the determination of Iron (II) spectrophotometrically. Beer's Law was obeyed between (0.4- 2.4 ppm) Iron (III). Optimum conditions were : pH(2-3), λmax= 560 nm, 2ml (0.001M) reagent freshly prepared for final 25ml solution containing 10 to 60 μg [i .e. 0.4-2.4 ppm Fe(III)], color develops after 10 minutes and remains stable for three hours.
Best Straight line drawn by the method of least square gave correlation coefficient of (0.999) between (0 - 2 ppm). At lower limit of Fe(III) determination (0.4 ppm), maximum error did not exceed 5% in the presence of accumulative interfering ions with coefficient of variation of 1.8% there values, for 2 ppm Fe(III), were less that 4% and 0.34% respectively. Average extinction coefficient was about (1.5 x 10^4 L.mol-1. cm-1). The Stoichiometry of the complex [ Fe(III) - R ] was 1:1.
Interferences of 27 ions were studied for their tolerance levels. Only few ions interfered seriously which were Cu2+, Ag+, Zn2+, Sn2+, C2O42-, and F-.
Chloride, nitrate, and calcium ion-selective electrodes were tested and found satisfactory for the determination of the corresponding ions in highly refined white sugar, molasses and other impure sugar samples at different stages of sugar manufacturing or refining. The interferences by Br-and Iions in C1-determination were eliminated by oxidation with 3 M HNOs and passing air to remove the free Br, and I, formed. The C1concentration was then determined with a chloride-selective electrode against a Calibration curve. Chloride should not be determined by ashing sugar, since this causes high losses of C1-. It was found that NO; and free Ca2+ ions could be determined directly in the sugar solution against corresponding calibration curves. Total calcium was determined after ashing of sugar samples. The ash was dissolved in 0.1 M HCl and passed through an anion exchange resin to remove PO:-and Si0;-ions, and Ca2+ was determined as before. Bound calcium was obtained by subtracting values of free from total calcium. Determination of bound calcium was useful to monitor the process of liming. For comparison, the three ions were also determined with acceptable precision without removing interfering ions using the method of standard addition and Gran's plot. The errors of determination for both direct and standard addition techniques were 3% for C1and NO; and 1-5% for Ca2+.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.