Rafidain Journal of Science

A simple, fast and precise high performance liquid chromatographic method for the assay of trimethoprim in the presence of sulphamethoxazole has been developed. The procedure is based on using acetonitril: water: acetic acid in the ratio of 30:69.9:0.1 (v : v : v) as a mobile phase, flow rate (1ml/min.) and uv detector (254nm.).Each analysis required no longer than 10 minutes. the detector responses were linear in the range of 0.05-120µg/ml for trimethoprim with a relative standard deviation of 0.49-0.971% and a relative error of 1-2.5% .
The proposed method was also applied satisfactorily to the pharmaceutical preparation.

Some new derivatives of 1,3,5-oxadiazine-4-one (7-9) and 1,3,5-oxadiazine-4-thione (10-12) were synthesized using two different diamides (N, N′-Diaroyl urea /thiourea Compounds (1-6)).
N, N′-Diaroyl urea /thiourea compounds (1-6) were prepared by the reaction of urea and thiourea with benzoyl chloride and substituted benzoyl chloride respectively under basic conditions. Cyclodehydration of the diamides under acidic conditions afforded the 1,3,5-oxadiazine compounds.
All compounds were identify by physical and spectroscopic methods.

The single-and multi-parametric linear regression analysis is applied for the study of the influence of different factors on the kinetic of 1,3-dipolar cycloaddition reactions. The rate constants of the addition of eight N-( substituted) maleimides on phthalazinium-2-dicyanomethanide(Butler et al., 1996) is correlated as dependent variable with the electron densities of the carbons involved in the addition reaction, the frontier orbital energy levels, and the steric energies of the transition states and products as independent variables. Results of the analysis revealed that all mentioned factors affect the rate of the reaction, but to different extents. The steric energy of the transition state and the electron density are the most influencing factors; the energy of the lowest unoccupied molecular orbital and the steric energy of the products come next. The energy of the highest occupied molecular orbital has the least influence on the reaction.

The research was concerned with a development of spectrophotometric method for the determination of trace amounts of dapsone. The method was based on the reaction of diazotized dapsone with phloroglucinol as azo coupling reagent in basic medium, to form an intense yellow coloured, water-soluble and stable azo-dye which showed a maximum absorption at 435 nm. Beer’s law is obeyed over the concentration range of 10-250 μg/25ml, i.e.,0.4-10 ppm with molar absorptivity of 4.79 × 104 L.mol-1. cm-1 and Sandell’s sensitivity index of 0.005 μg.cm-2, a relative error of + 0.12 to -0.34% and a relative standard deviation of ± 3.96 to ± 0.85% ; depending on the concentration level. The method does not require temperature control or solvent extraction and has been applied successfully to the determination of dapsone in pharmaceutical preparation (Tablet).

UV Derivative spectra were used for the direct quantitative determination of Prednisolone in absolute ethanol, the quantification was accomplished according to the integrated area under the peaks. The zero-order spectrum of Prednisolone show an absorption band at  = 242nm, with molar extinction coefficient max = 13770 lit. mol-1. cm-1, the determination range was (0.36-50.46) g/ml with R2 =0.9998 and relative standard deviation RSD =1.28 %.
The determination ranges were (0.10- 72.09) g/ml, (0.36-72.09) g/ml for first and second-order derivatives respectively with R2 = 0.9999, 0.9998 and RSD = 1.53%, 2.55% respectively.
This indicate a more sensitive and accurate results as compared with the zero-order method. These methods were applied for the direct determination of the PRISOLONE tablets.

Ninivite is a silica rich rock, which has a very high surface area, that may exceed (800g/m2). Low grad ninivite is characterized by high absorption, adsorption ability and may act as an ion exchange to remove heavy metals. Efforts of applications under study are in the field of waste water treatment. Washing operation of ninivite with distilled water to reduce impurities; such as gypsum; and increasing silica ratio rendered it to be inefficient to removing mercury from its effluents. In the mean time the adsorptive materials such as alum and iron sulfate, are also washed out. It was found that the unwashed, raw, low grade, ninivite was outweighing washed one, using different concentrations of mercury(0-200mg/L) and at different pH values (1.6, 7.4, 9.5, and 10.6). Optimum removal efficiency of mercury concentrations of 75mg/L and 175 mg/L were at a pH of 9.5 and7.5 respectively.

Amidoxime (2) was prepared from the reaction of carbonitrile (1) with hydroxyl amine hydrochloride. Compound (2) treated with either acid chloride or anhydride at room temperature to obtain O-aroyl and O-acetyl amidoxime (3a-c). However, on heating compound (2), oxadiazole derivatives (4a-c) were obtained, respectively. 1,2,4-Oxadiazole-5-one (5) was obtained from the reaction of amidoxime with phosgene. Amidine (7) also prepared from imidiate reaction with ammonium chloride.
A number of heterocyclic compounds (8-10) were also prepared by the reaction of imidate (6) with either amino derivatives or azide. Imidate (6) was prepared from the reaction of carbonitrile with ethanol in the presence of hydrogen hydrochloride gas.

The measurement of dose distribution for any radiotherapeatic device is essential for good treatment planning. Therefore, dose distribution were measured for the field size [F.S = (10x10)cm²], then we use mathematical equation according to Fermi-Dirac distribution law after modified it, in this equation two parameter (k) and (n) are directly related to the field size (a), and the depth (d). So we can contract a theoretical curve by calculating (k), (n) and putting them in to this equation.