Simultaneous Determination of CGS 10787B and Its Major Metabolite (CGS 12094) in Plasma by High Performance Liquid Chromatography

Abstract

A method for the simultaneous determination of CGS 10787B and its major, metabolite (CGS 12094) in plasma is described. The two compounds, and the internal standard (dichlorinated analog), are extracted from acidified plasma with ethyl acetate, taken to dryness, and reconstituted in chromatographic mobile phase. The analytes are determined automatically by high performance liquid chromatography in the reversed-phase mode as paired ions, using [N(Bu)₄]⁺ as the counterion. The separation of the compounds is achieved on a 3u C-8 column, with detection at 254 nm.

Recovery and reproducibility assessments indicate good accuracy and precision over the range of 1.0 to 250 ug/ml for CGS 10787B and 1.0 to 100 ug/ml for CGS 12094.

The method has a limit of detection of 0.2 ug/ml for both compounds, and has been shown to be adequate for studying the disposition kinetics of CGS 10787B.     

Multiwavelength Spectrophotometric Determination of Acid Dissociation Constants. Deconvolution of Binary Mixtures of Ionizable Compounds

ABSTRACT

A spectral deconvolution method based on target factor analysis has been developed to determine pK_a values of binary mixtures of monoprotic and/or diprotic ionizable compounds. The technique makes use of the approach of Frans and Harris, which has been implemented previously for mixtures of monoprotic compounds (Anal. Chem. 1985, 57, 1718-1721), to extract the unknown pK_a values. The method has been illustrated by using the multiwavelength spectrophotometrictitation data of binary mixtures of: I. benzoic acid and phenol, 2. benzoic acid and nicotinic acid, 3. p-aminosalicylic acid and phthalic acid. It was demonstrated that the pK_a values as determined in this study are in good agreement with the literature.     

Novel Flow Injection/Potentiometric Measurement of Slightly Soluble Salts in Small Volumes: Determination of Solubility Product Constants of Some Silver Salts

Abstract

The flow injection technique is shown to provide fast, reliable and sensitive determination of solubility product constants of silver acetate, silver sulfate, silver oxide, silver bromate and silver chloride in microliter volume samples. Potentiometric detection using electrodes of the first kind and second kind was used for measuring silver ions and chloride ions, respectively. The solubilities were determined from measurement of the silver ion concentration in the saturated solutions. In the case of silver chloride, the solubility product constant was calculated from the concentrations corresponding to the intersection of the silver ion calibration curve and the chloride ion calibration curve, i.e., where the potentials of the two electrodes are equal. Tenth-molar sodium nitrate was used for all solutions to maintain constant ionic strength. At a concentration range of 1.00 × 10^?2 ? 1.00 × 10^?5 M silver, and 1.00 × 10^?2 ? 1.00 × 10^?4 M chloride, a Nernstian response of 60 m V per decade was obtained. At a sampling rate of 50–70 samples per hour, with 50 μl sample injections, high reproducibility of measurements was achieved, with a -pL 2% relative standard deviation in measured concentrations. The scope and applications of this system are discussed.     

Spectrochemical Determination of Some Elements in Zinc Samples Using Glow Discharge Lamp

Abstract

Results in spectrochemical analysis with optical emission spectroscopy(OES) are affected by matrix. Analysis of zinc samples are difficult with other emission excitation sources as arc and spark, since zinc is a volatile element. For this reason, metallic zinc samples and its low alloys were analysed by using a glow discharge lamp in this work. Interelement effects were also investigated in the determination of Al, Cu and Mg in the samples.     

Indirect Atomic Absorption Spectrometric Determination of Ammonia,Thiosulfate and Cyanide in an Unsegmented Flow System

Abstract

A flow injection analysis method (FIA), has been developed for the determination of cyanide, thiosulfate and ammonia by atomic absorption spectrometry (AAS). Aqueous solution of the analyte was injected into an on-line column containing glass beads and packed with silver chloride and deionized water was used as the carrier. The analyte dissolves the silver chloride and the dissolved silver complex is introduced to the nebulizer of the AAS. This method has proved to be sensitive, simple and precise. Detection limits of 1.0 × 10^?7 M, 5.0×10^?7 M and 5.0x10^?6M were obtained for thiosulfate, cyanide and ammonia, respectively. The precision of the technique was 2.0%, 2.4% and 1.4% in case of thiosulfate, cyanide and ammonia, respectively. The effects of flow rate and sample volume on the FIA/AAS signals are presented.     

A Jet Ring Cell with a Renewable Solid Support for Amperometric Detection of Glucose in a Sequential Injection Analysis System

Abstract

A new amperometric method for the detection of glucose has been developed. A jet ring cell with a renewable solid support (JRR) is connected to a sequential injection analysis (SIA) system. The solid support, consisting of small spherical particles of agarose gel, with a mean bead size of 90 μm, is coupled with the enzyme glucose oxidase (GOD). The suspension is injected through a multiport valve in the SIA-system and is trapped in the JRR cell by a gap of 10 μm between the glassy carbon (GC) working electrode and a stainless steel counter electrode. The subsequent injection of glucose results in formation of hydrogen peroxide, which is detected by oxidation at 1.0 V (vs. Ag/AgCl/KCl (3 M)). Thereafter the suspension is removed by reversing the pump flow and subsequently replaced with fresh suspension for the next determination of glucose. The linear working range for the JRR-sensor, at this stage of the work, is 100 μM - 5 mM.     

Development of an Automated Procedure for the Optimization of Multielement Analysis with Energy Dispersive X-Ray Fluorescence Spectroscopy

Abstract

A system is devised that automatically optimizes energy dispersive x-ray spectrometer settings for multielement determinations under compromise conditions using self-sustained search algorithms. As an objective function, the joint probability of detecting all elements was chosen. The current process is to date limited by the resolution of the commercially available automatic power supply employed. Typical optimization times needed for the entire procedure are on the order of 5 minutes for major constituents, with prolonged times for minor and trace elements as a result of increased counting time to obtain good counting statistics.     

Indirect Determination of Bromhexine by Atomic Absorption Spectrophotometry

Abstract

A new procedure for determination of Bromohexine is described. The method consists of extracting an ion pair between the Bromhexine and the inorganic complex Co(SCN)² ₄ and measuring Co in the organic phase by AAS at 240. 7 nm. The optimal experimental conditions: pH, concentration of Co(SCN)² ₄, shaking time, phase ratio, number of extractions and the linear range of calibration are studied.

The organic phase used is 1,2-dichloroethane. The standard deviation of the method is 10^?3. The interference of foreign substances which accompany the Bromhexine in pharmaceutical preparations is studied, and the method is applied to their quantitative determination in medicines.     

Spectrophotometric Determination of Mercury Using 2-(5-Bromo-2-pyridylazo)-5-diethylaminophenol

Abstract

Mercuric ion with 5-Br-PADAP forms a 1:2 complex at pH 8.0–10, which, with the addition of Triton X-100, has a molar absorptivity of 1.10 × 10⁵ at 565 nm. A method is described for the determination of mercury in industrial waste water and sludge.     

First-Derivative Spectrophotometric Determination of a Mixture of Pirbuterol Hydrochloride and Butorphanol Tartrate

Abstract

Vierordt's method, its modified version and the first derivative method have been applied for the simultaneous determination of butorphanol tartrate and pirbuterol hydrochloride in laboratory mixtures of authemtic and dosage forms. The first derivative spectrophotometric method yields accurate and reprodeucible results for both drugs. Mean percent recoveries for butorphanol tartrate and pirbuterol hydrochloride in dosage forms were 100.54±0.84 and 100.42±1.27, respectively. Virrordt's method and its modified version have given unreliable results; the reasons behind have been discussed.