A simple, sensitive and rapid method based on the application of the differentialpulse polarography of the diazonium salts of 0-, m-and p-aminobenzoic acid for the determination of trace amounts of nitrite is described. The reagents required are readily available and non-toxic. The detection limits using the 0-, m-and p-aminobenzoic acids were 0.87 X and 4.30 x 10-7 M, respectively, with relative standard deviations of between 9 and 10%.
In the first part of this work we have measured the electrical conductivity of 4-amino salicylic acid (4-ASA) solution in water, methanol and ethanol at different temperatures (293.16-313.16 K). The experimental results were analyzed using Lee-Wheaton equation (LW) for symmetrical electrolytes (1:1). The conductivity parameters were calculated: the equivalent conductivity at infinite dilution (Λ o), the association constant (K A) and the mean distance values between ions (R) at the best standard deviation σs(Λ). It is found that by increasing the temperature, the values of Λ o increased, in contrast of that the values of K A decreased in ethanol only, R are found to be between (2-29)A o which indicates the formation of solvent separated ion pairs in solution. By Vant Hoff equation we have calculated the thermodynamic parameters (∆G, ∆H and ∆S) of ion association in solution. The second part of this work is the measurement of electrical conductivity of (4-ASA) in water with chlorides of each of nickel, cobalt and manganese at different temperatures (293.16-313.16 K) and calculation of conductivity parameters by Lee-Wheaton equation for unsymmetrical electrolytes (2:1), besides the thermodynamic parameters were also performed. The Walden-product (Λ o η) was also determined and discussed.
The UV fourth order derivative spectra were selected as the more reliable technique for the direct quantification of pure Tetracycline Hydrochloride in water, after the measurement of the zero, first, second, third and fourth order spectra, within the concentration range at (0.2885-144.27)µg/ml with R 2 =0.9998 and RSD=0.215 %. Bovine serum albumin was directly quantified by the fourth order UV derivative technique within the concentration range (6.7-2680) µg/ml with R 2 = 0.9998 and RSD=0.324 %. Appreciable interaction between Tetracycline hydrochloride and Bovine serum Albumin was found in accordance with the fraction coefficient and the apparent binding constant. The UV-fourth order derivative technique appears to be in a good accuracy and precise method for the direct quantification of Tetracycline Hydrochloride and Bovine Serum Albumin (BSA) in water.
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