Summary
The study was performed to compare the dissolution rates of six of the popular brands of 100 mg phenylbutazone tablets available on the British market. The standard USP dissolution method was used for evaluation. The USP requires 60% of the labelled amount to dissolve in not more than 30 min. On this basis the performance of three brands was satisfactory, that of one brand marginal and two brands did not meet the USP requirements.
Summary
A rapid and sensitive method for the determination of phenylmercuric nitrate has been developed. After extraction with chloroform, the sample is evaporated to dryness and redissolved in the small amount of chloroform. Injection is made on a silica gel column at 4130 kPa. The mobile phase is hexane‐ethanol (9:1) and the phenylmercuric nitrate is detected at 230 nm. Peak areas relative to an internal standard (chloroform) are used to calculate the unknown concentration. The detection limit is about 1–5 times 10‐3 g/l and the samples are analysed with errors of less than 10%. The proposed method is applicable to solutions of phenylmercuric nitrate and certain eye‐drops.
Summary
A procedure for the rapid determination of pethidine in plasma is described. It involves a preliminary separation by solvent extraction and the separation of pethidine on a silica gel column at 2070 kPa. The mobile phase is hexane‐ethanol‐acetonitrile (65: 30: 5) and the wavelength of determination is 230 nm. 0.08% codeine phosphate in ethanol is used as an internal standard and the peak height ratio of drug to internal standard is used for drawing the calibration curve and measuring the concentration of the drug in the spiked plasma samples.
Summary
The in vitro dissolution rates of ampicillin 250 mg and 500 mg capsules from different companies were measured. The dissolution in simulated gastric fluid in 20 min ranged from 80% to virtually 100% of the stated content. In water the dissolution time in this range was 30 min. Intra‐ and inter‐batch variations were found to be relatively insignificant.
Summary
The performance of the Shandon UK3 gas chromatograph (incorporating a katharometer detector) was examined critically under various experimental conditions such as column flow rate, temperature changes and detector current. The work was done to establish optimum conditions for the identification of medical gases, i.e. compressed air, oxygen, nitrogen, nitrous oxide and Entonox. Certain light hydrocarbons were also studied with a view to finding suitable internal markers. Porapak Q (PQ) and a molecular sieve (MS) were used as stationary phases.
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