ABSTRACT
In this study, simple, fast and reliable cyclic voltammetry, linear sweep voltammetry, square wave voltammetry and differential pulse voltammetry methods were developed and validated for determination of etodolac in pharmaceutical preparations. The proposed methods were based on electrochemical oxidation of etodolac at platinum electrode in acetonitrile solution containing 0.1 M lithium perchlorate. The well-defined oxidation peak was observed at 1.03 V. The calibration curves were linear for etodolac at the concentration range of 2.5-50 µg/ml for linear sweep, square wave and differential pulse voltammetry methods, respectively. Intra- and inter-day precision values for etodolac were less than 4.69, and accuracy (relative error) was better than 2.00%. The mean recovery of etodolac was 100.6% for pharmaceutical preparations. No interference was found from three tablet excipients at the selected assay conditions. Developed methods in this study are accurate, precise and can be easily applied to Etol, Tadolak and Etodin tablets as pharmaceutical preparation.
ABSTRACT
Molecules of the title compound, C12H10N4O4S, are linked through intermolecular hydrogen bonds to form a dimeric structure. The crystal structure of the dimer is stabilized by two intermolecular hydrogen bonds of the C-H...O type. The C...O intermolecular contact distance is 3.339(3) A, and the C=N and N-N distances are 1.279(2) and 1.371(7) A, respectively. One O atom of the 2-nitro group is disordered over two sites.
Subject(s)
Anti-HIV Agents/chemistry , Dinitrobenzenes/chemistry , Thiophenes/chemistry , Antineoplastic Agents/chemistry , Crystallography, X-Ray , Dimerization , Hydrogen Bonding , Models, Molecular , Molecular StructureABSTRACT
The origin of stress in adhesive resin composite restorations is attributed to restrained shrinkage during polymerization and is dependent on the configuration of the restoration. Moreover, non-homogeneous deformations during functional loading can damage the interface as well as the coherence of the material. Damage from these stresses can be reduced by application of an elastic lining at the adhesive interfaces and by slowing the initial conversion by two-step light initiation of the resin. The various factors that mediate flow and compliance are discussed.
Subject(s)
Composite Resins/chemistry , Dental Cavity Lining , Dental Marginal Adaptation , Dental Restoration, Permanent , Dental Stress Analysis , Composite Resins/radiation effects , Dental Bonding , Elasticity , Humans , Light , Polymers/chemistry , Stress, Mechanical , ViscosityABSTRACT
OBJECTIVES: This study evaluated the influence of light intensity and irradiation time variations on the curing efficacy of two types and various shades of resin composites and the effect of reduced light intensity on the preservation of wall-to-wall continuity. MATERIALS AND METHODS: Three microfilled composites (in three different shades) and one hybrid composite were used in this study. Polymerization shrinkage, and the hardness and adaptation of adhesive restorations in dentin cavities were determined at light intensities of 175 and 700 mW/cm2 and irradiation times of 10 and 60 s. Data were compared using in a general linear model analysis. RESULTS: Shrinkage measurements were the indication of conversion and conversion rate. Reduced intensity slowed down the rate of polymerization but did not reduce the conversion as long as an irradiation time of 60 s was employed. High-energy irradiation caused increased separation of the composite from the tooth structure. On the basis of obtaining optimal conversion and adaption, it was demonstrated that the irradiation time to be more effective than irradiation energy. SIGNIFICANCE: Light-cured composites require an understanding of their structure, pigmentation and irradiation parameters to obtain optimal performance. High intensity light-curing does not necessarily lead to optimal quality.
