A simple, developed, fast and accurate spectrophotometric method to determination Mesalazine (MES) in its pure form and pharmaceutical preparation (Pentasa). This method was based on the formation of a charge transfer complex between MES and the Iodine (IOD) reagent to give a purple color product that gives its highest absorption at the wavelength of 514 nm. The best conditions for complex formation were found (time, temperature, optimal reagent concentration and pH). The linearity of the method for the complex consisting ranged from 5-45 µg/ml, the Sandell's index was 0.03278 µg/cm2, the molar absorption coefficient was 4670.6175  L/mol.cm and the detection limit was 0.10245 µg /mL, the quantitative limit was 0.31045  µg/ml, the percent recovery range was Rec% between (103.145 - 97.311 ) % and the relative standard deviation range RSD% between (0.128  -  0.263) %. It was found that the method is accurate , precision and has been successfully applied to determinate MES in its pharmaceutical preparation, in direct methods and in multi standard additions.

A simple, sensitive and economical spectrophotometric method for simultaneously estimation of PRO and HCTZ. The first derivative (D1) of the UV spectrum was used in the determination of both drugs in their synthetic mixtures. The Peak to baseline and Peak area at suitable wavelengths were used in the study. The linearity of both drugs was up to a concentration of (5-40 µg/ml). The analytical results of the estimation of PRO were, Rec% 97.179-102.424% and RSD% 0.001-4.996 %. While for estimation of HCTZ were, Rec% between 95.406-103.681% and RSD% 0.001-3.676%. The method was accurate, good repeatability and successfully applied in the estimation of both drugs in their synthetic mixtures.

A new, sensitive, simple and cheap spectrophotometric method for the determination of Neomycin Sulphate (NEO) in pharmaceutical forms has been developed. The method is based on the reaction between NEO and NIN in basic medium. The maximum absorbance was at 574 nm. The conditions affecting the reaction were optimized. Under the optimal conditions, the calibration curve was linear over the range of 0.0002-0.0011 mol/L. The limit of detection and limit of quantification were 5.423×10-6 mol/L, and 1.643×10-5 mol/L, RSD% of seven replicate was 0.8217- 0.8321% and Rec% was between 99.2168-100.8857%. The proposed method was successfully applied to the determination of NEO tablets form.

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