& A highly sensitive liquid chromatography-tandem mass spectrometry (LC-MS=MS) method was developed and validated for the quantification of venlafaxine (VEN) and its active metabolite O-desmethyl venlafaxine (ODV) in human plasma using fluoxetine as an internal standard. The VEN and ODV were extracted by liquid-liquid extraction using MTBE-n Hexane (60:40), and chromatographed on X-terra RP8 (50 mm  4.6 mm, 5-lm particle size) column eluted with a isocratic mobile phase of 10 mM Ammonium acetate (pH 4.50 AE 0.05) and acetonitrile in 10:90 (v=v). The detection was performed by positive ion electrospray ionization in multiple reactions monitoring mode, monitoring the transitions m=z 278.27! 121.08 and 264.33 ! 57.72 for venlafaxine and O-desmethyl venlafaxine, respectively. The assay was linear over the concentration ranges of 0.100-300.010 ng=mL for VEN and 0.200-600.050 ng=mL for ODV with limits of detection and quantification of 0.050 ng=mL for VEN and 0.100 ng=mL for ODV, respectively. This LC-MS=MS method was validated with Intra-batch and Inter-batch precision 1.65-10.80 for VEN and 1.27-7.08 for ODV, respectively. The Intra-batch and Inter-batch %accuracy was 91.77%-104.39 % for VEN and 95.87%-106.28% for ODV, respectively. This method was successfully applied to a pharmacokinetic study of venlafaxine hydrochloride extended release capsules 150 mg steady-state bioequivalence study.

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New, rapid and sensitive spectrophotometric methods have been developed for the determination of Oxytetracycline (OTC) and Hostacycline (HTC). The procedure is based on the observation that, OTC or HTC forms colored complexes with Zirconium (IV), the absorbance of which is proportional to the amount of tetracycline present. The variables affecting development of the color have been investigated and the conditions are optimized. Beer's law is obeyed in the range 1.0-33.5 µg/ml for OTC and 4.0-40.0 µg/ml for HTC. The proposed methods can be employed for the analytical determination of Zirconium (IV). The corresponding Beer's law ranges are 0.2-6.1 µg/ml with OTC and 0.5-7.3 µg/ml with HTC. Stoicheiometry of the complexes, regression parameters and relative standard deviation are reported for each of these determinations. The methods are successfully applied for the determination of OTC and HTC in pharmaceutical formulations and urine.

In this work Cefotoxime (CFX) and its Cd (II) and Cu (II) metal complexes determination were carried out by spectrophotometric method. The following experimental procedures like effect of pH, effect of metal ion concentration, effect of drug concentration, effect of time, effect of organic solvents and the composition of the complex by mole ratio and job's continuous variation method and interference studies were carried out for the determination of metal ions and drug. In this research work, it is clear that Cd forms a stable 1:1 colored complex with CFX in basic medium and Cu forms stable 1:1 colored complex with CFX in acidic medium. Effect of pH was studied for CFX-Cd (II) and CFX-Cu (II) complexes; it is noticed from that at pH 11 CFX-Cd (II) and at pH 5.5 CFX-Cu (II) colored complexes were formed. In these reactions can be found the metal ions in the range 1.12 to 6.74 and 3.812 to 8.895 µg/ml and the drug in the range 0.02 to 0.14 mg/ml respectively for CFX-Cu (II) and CFX-Cu (II) complexes. Effect of time clearly suggest , that the maximum absorbance is obtained only after heating the mixture to 40 o & 60°C respectively for CFX-Cd (II) and CFX-Cu (II) complexes. It has been observed that the absorbance values remain constant thereafter; it indicates the formation of 1:1 stable metal complexes.

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