ABSTRACT

Zidovudine is considered a good candidate for incorporation in a gastro-retentive dosage form due to its high solubility in the stomach medium compared with its solubility in the small intestine medium. As its solubility decreases with increase in pH, it would be more beneficial to retain the drug in stomach (acidic environment) for prolonged duration so as to achieve maximum absorption and bioavailability. Zidovudine is the first approved compound for the treatment of aids; however the limitation for the therapeutic effectiveness of zidovudine is its dose-dependent toxicity, short biological half-life and poor bioavailability. The present research work, an attempt has been made to develop the zidovudine gastro-retentive dosage form for controlled release.

Keywords: Zidovudine, Gastro-retentive dosage, Controlled release.

ABSTRACT
X-ray fluorescence (XRF) spectrometry is an elemental analysis technique with broad application in science and
industry. XRF is based on the principle that individual atoms, when excited by an external energy source, emit X-ray photons of a characteristic energy or wavelength. By counting the number of photons of each energy emitted from a sample, the elements present may be identified and quantities.

Keywords: X-ray fluorescence, Sources, Detectors and Applications.

ABSTRACT

Attenuated Total Reflectance (ATR) is today the most widely used FTIR sampling tool. ATR generally allows qualitative or quantitative analysis of samples with little or no sample preparation which greatly speeds sample analysis. The main benefit of ATR sampling comes from the very thin sampling path length or depth of penetration of the IR beam into the sample. This is in contrast to traditional FTIR sampling by transmission where the sample must be diluted with IR transparent salt, pressed into a pellet or pressed to a thin film, prior to analysis to prevent totally absorbing bands in the infrared spectrum. In transmission spectroscopy, the IR beam passes through the sample and the effective path length is determined by the thickness of the sample and its orientation to the directional plane of the IR beam.

Keywords: ATR,Critical angle,Total internal reflection,Evanescent waves.

ABSTRACT
The phenomenon of molecular fluorescence emission contains both spectral and time information it is former which
has traditionally been more usually associated with routine analytical applications of fluorescence spectroscopy. In contrast, since the early seventies, the most important strides in fluorescence spectroscopy have been by and large concerned with the development and application of new time resolved techniques. Applications of these now span not only in the traditional areas of photochemistry but also research in polymers, membranes, liquid crystals, low-dimensional structures, solar energy, and semiconductors, to name but a few. Such diverse areas are linked by their common instrumentation needs, which have greatly benefited over the past decade from quite radical progress in optoelectronics and on-line data analysis. There is now widespread recognition of the advantages of studying and using fluorescence in the time domain. Quite simply, fluorescence measurements in the time domain (fluorometry) posses a much greater information content about the rates and hence kinetics of intra and intermolecular processes than is afforded by the wavelength spectroscopy of the energy domain (fluorimetry). A simple analogy to the greater detail shown by time domain as compared to steady state fluorescence measurements is that of motion pictures in
comparision to still photographs. The rising importance of fluorescence measurements in the time domain has been reflected during the past decade in several texts devoted exclusively to this topic. Nevertheless, the field has not stood still, and, if anything, the rate of innovation has probably increased over the past few years.

Keywords: Time correlated single photon counting, Fluorescence lifetime, Photon signals, Luminescence.

ABSTRACT

Micellar electrokinetic chromatography (MEKC) is a useful branch of capillary electrophoresis (CE) that utilizes surfactant above critical micellar concentration (CMC) as pseudo-stationary phase. MEKC can be employed to separate both charged and neutral molecules, individually or simultaneously, including chiral compounds. MECK benefits from high peak efficiency due to electroosmotic flow (EOF) in the separation capillary, compounded with large variety of synthetic surfactants, organic modifiers, temperature and variable separation voltage has made MECK. In this review, we present the introduction of CE, fundamentals of surfactant chemistry as it relates to MEKC, separation principles in MECK including equations involved in calculating separation parameters.

Keywords: Micelles, Surfactants, Buffer additives, Optimization parameters.

ABSTRACT

Fingerprint analysis approach using HPLC has become the most potent tools for quality control of herbal medicines because of its simplicity and reliability. It can serve as a tool for identification, authentication and quality control of herbal drugs. It plays an important role in the quality control of complex herbal medicines. Chemical fingerprints obtained by chromatographic techniques are strongly recommended for the purpose of quality control of herbal medicines, since they might represent appropriately the “chemical integrities” of the herbal medicines and therefore be used for authentication and identification of the herbal products. Based on the concept of phytoequivalence, the chromatographic fingerprints of herbal medicines could be utilized for addressing the problem of quality control of herbal medicines. It has been accepted as a tool to establish the Chinese medicine quality standard system.

Keywords: Phytoequivalence, Quality Assurance, Qualitative Identification, Quality Control.

ABSTRACT

Determination of reactive oxygen species (ROS) in erythrocytes have been extensively studied due to its important pathophysiological role in many diseases. Also, studies on the potential of many antioxidants compounds are important to improve human healthy. This paper describes a simple and fast method to quantify ROS in erythrocytes with induction of oxidation and antioxidant protection. Tert-butyl hydroperoxide (tBOOH)-induced ROS was measured in erythrocytes isolated from 60 healthy adults between 21 and 39 years old, using microplates methods in which 2,7-dichlorofluorescein (DCF) was produced. Fluorescence was monitored at 530 nm after excitation at 495 nm. Data points were taken after 15 and 30 min of incubation at room temperature and at 37°C. Ascorbic acid was used to evaluate the protection of an antioxidant compound. Results were analyzed using the Statistica 10.0 (StatSoft). No outlier was identified and all parameters were normally distributed. Data were expressed as mean ± standard deviation and one-way analysis of variance (ANOVA) and Tukey test were performed. Results were considered statistically significant when p<0.05. Different concentrations of t-BOOH solutions induced ROS generation with significant differences in all concentrations. Time and temperature interfere in the method that has to be well standardized. Dose-dependent protection of ascorbic acid on ROS production was observed. ROS-induced oxidative stress in erythrocytes and antioxidant protection can be determinate using an easy and fast method, with little blood volume under microplate methods.

Keywords: Reactive oxygen species, Erythrocytes, Tert-butyl hydroperoxide, Dichlorodihydrofluorescein-diacetate.

ABSTRACT
HPLC and UPLC Systems take advantage of technological strides made in particle chemistry performance, system
optimization, detector design, and data processing and control. When taken together, these achievements have created a stepfunction improvement in chromatographic performance.Although HPLC method development has been improved by advances in column technology and instrumentation, problems still arise. This helps in systematic means of isolating, identifying, andcorrecting many typical problems. The important segments of an HPLC and UPLC system are the same,  whether you use a modular system or a more sophisticated unit except the column characteristics. Problems affecting overall system performance can arise in each component. Solutions to these problems are presented in easy-to-use tables.
Keywords: Monolithic columns, Baseline drift, Shouldering peaks, Fronting peaks, Inline filter, Radio Interference, etc.

ABSTRACT

High performance liquid chromatography (HPLC) is an analytical technique which is proficient to separate, detect and quantify various drugs and its related degradants. An appropriate mobile phase, column, column temperature, wavelength and gradient must be found that affords suitable compatibility and stability of drug as well as degradants and impurities. This review covers the importance of RP-HPLC in analytical method development and their strategies along with brief knowledge of critical chromatographic parameters need to be optimized for an efficient method development.

Keywords: Method validation, Method development, High PressureLiquid Chromatography (HPLC).

ABSTRACT

A new precise, accurate, reliable validated method for the determination of Olanzapine and Fluoxetine has been developed by using reverse phase high performance liquid chromatography (RP-HPLC) in pharmaceutical dosage form. Chromatographic separation was carried out by using mobile phase 0.01M Phosphate buffer PH 5.8: Acetonitrile (55:45v/v, PH-2.6 adjusted with Orthophosphoric acid) on HYPERSIL ODS C18 (250 x 4.6 mm, 5) at a flow rate 1ml/min with UV detection at 261nm.The retention times for Olanzapine and Fluoxetine were 3.480 and 2.597 min respectively and both drugs showed good linearity in the range of 18-42μg/ml and 72-168μg/ml. The proposed method has been successfully applied to marketed formulation and was validated according to ICH guidelines and method showed good precision with percentage relative standard deviation less than 2%. The percentage recovery for Olanzapine and Fluoxetine was found between 100.3 and 99.3 respectively indicating the proposed method was accurate and precise.

Keywords: Olanzapine(OLZ) ,Fluoxetine(FLU), RP-HPLC, Simultaneous estimation.