Biomedical subjects

Xiancheng Zhan

Publications and source records attributed to Xiancheng Zhan.

5 recordsLinked to original sources

PubMed2007

Compressed oxygen in drug stability experiments.

A drug stability experiment accelerated by compressed oxygen was established. The stability of 10% ascorbic acid solution as a model was studied and the kinetic parameters were obtained with the newly established experimental method. Because ascorbic acid degrades under both anaerobic and aerobic conditions, the total rate constant k(total) can be expressed as: k(total)=k(anaerobic) + k(aerobic), where k(anaerobic) and k(aerobic) are the rate constants of anaerobic and aerobic degradations, respectively. The k(anaerobic) can be expressed as k(anaerobic) = A(anaerobic) x exp(-E(a,anaerobic)/RT) according to Arrhenius equation, and the k(aerobic) was found to be k(aerobic) = A(aerobic) x exp(-E(a,aerobic)/RT) x p(O2) in our study.

Ascorbic Acid↗

PubMed2005

Determination of promethazine hydrochloride and its preparations by highly accurate nephelometric titration.

A highly accurate nephelometric titration for the determination of promethazine hydrochloride and its preparations was presented. The titration operating conditions were studied and the solubility product constant of promethazine tetraphenylboron precipitation was determined. The result of the titration is comparable to those of control experiments. The proposed method has been found to be accurate, precise, specific and linear.

Nephelometry and Turbidimetry↗

PubMed2005

Determination of norfloxacin by highly accurate nephelometric titration.

A highly accurate nephelometric titration for the determination of norfloxacin is presented. The titration operating conditions were studied and the solubility product constant of norfloxacin-tetraphenylboron precipitation was determined. The result of the titration is comparable to those of control experiments. The proposed method has been found to be accurate, precise, specific, and linear.

Nephelometry and Turbidimetry↗

PubMed2005

Programmed humidifying in drug stability experiments.

The stability of penicillin potassium, as a solid state model, was investigated by a programmed humidity and temperature controlled method. An optimization calculational approach to data handling is suggested. The stability of drugs which are unstable to both heat and moisture could be studied by a single pair of experiments, one with programmed humidity control and one non-isothermal, rather than many standard isothermal studies, each at constant relative humidity. The controlling system, based on a pocket computer, was found to be accurate and reliable. The results indicated that the kinetic parameters obtained were comparable to those from isothermal studies.

Drug Stability↗

PubMed2004

Highly accurate nephelometric titrimetry.

A method that accurately indicates the end-point of precipitation reactions by the measurement of the relative intensity of the scattered light in the titrate is presented. A new nephelometric titrator with an internal nephelometric sensor has been devised. The work of the titrator including the sensor and change in the turbidity of the titrate and intensity of the scattered light are described. The accuracy of the nephelometric titrimetry is discussed theoretically. The titration of NaCl with AgNO(3) serves as a model. A relative error as well as deviation is within 0.2% under the experimental conditions. The applicability of the titrimetry in pharmaceutical analyses, for example, phenytoin sodium and procaine hydrochloride, is generally illustrated.

Chemistry, Pharmaceutical↗