ABSTRACT
【Objective】 To develop and verify a kinetic method for the determination of prekallikrein activator (PKA) content. 【Methods】 The optimal reaction conditions were determined by comparing the factors of pH and ionic strength of different sample dilution buffers, incubation time of each procedure, and incubation temperature. The accuracy, specificity, precision, linearity, stability and durability of the method were validated. 【Results】 The sample was diluted with 0.05 mol/L Tris-HCl buffer (pH8.5, containing 0.15 mol/L NaCl) and incubated by prekallikrein (PK) at 37℃ for 20 min. After that, the substrate S-2302 was added. Within 10 min before the measurement, the absorbance change rate reached △A405/min. The validation results indicated that the linear range of the method was (0.5~4.0)IU/mL, while the recovery of calibration standard was 96.9%~103.7% with the R2 value more than 0.99. The specificity test showed that human serum albumin, excipients of intravenous human immunoglobulin (pH4), low pH and protein content had no significant effect on the detection of PKA, The recovery rates of standard sample solution in the specificity experiment were 98.0% (0.9% sodium chloride solution), 95.3% (0.46% sodium caprylate solution), 96.7% (10% maltose solution, pH4.0), 94.0%(20%BSA), and 94.0%(5%BSA, pH4.0), respectively. The accuracy and precision of the method can meet requirements in the range between 0.5 and 4.0 IU/mL. The inter-batch recovery rate of quality control samples were between 96.4%~109.5% with the coefficients of variation(CV) between 0.2%~6.9%, while the intra-batch recovery rate were between 101.5%~102.9% with the CV between 2.6%~5.9%. The linearity, accuracy and precision of the assay can meet the requirements when PK and S-2302 were placed at room temperature for less than 6 hours, with the recovery rate of quality control samples between 94.9%~109.9%. The end-point method and kinetic method were used to determine the PKA in 20 batches of human serum albumin, and the consistency showed that there was no significant difference between the two methods(P>0.05). 【Conclusion】 A kinetic method for determination of PKA content with good linearity, specificity, accuracy, precision, stability and durability has been established. Compared with the method in ChP, the new method is more convenient, accurate and rapid to determine the content of PKA in human albumin and human immunoglobulin (pH4) for intravenous injection.
ABSTRACT
Measurement of drug solubility is one of the key elements of compound characterization during the drug discovery and development process. A broad variety of solubility assay methods have been developed, including equilibrium method which requires analysis of the equilibrium composition and kinetic method which monitors the concentration of a compound dynamically at the time when a precipitate first appears or disappears in the solution. Despite the numerous experimental methods, precise drug solubility values are hard to obtain for time-consuming, sample size and manual work. In this article, we reported a new method, namely air humidity solubility assay, which measures the relative humidity of the air in equilibrium with the solution at a given temperature, and then calculates solubility from the relative humidity according to extended-non random two liquid (NRTL) model. NaCl was used as a model drug, and the solubility was measured at the temperature of 20-50℃. The results indicate that the solubility of NaCl determined with the new method is generally comparable to that determined by gravimetry that is reported in literature. The new method has a relative error of less than 2%. Although the accuracy is lower than that of gravimetry, air humidity solubility assay is more convenient, practical, operational and universal. This method provides a supplement to the existing methods.
ABSTRACT
Objective To investigate the clinical application of ALT detection based on microtiter plate kinetic method in the au‐tomatic enzyme immunoassay system .Methods By beference to the IFCC recommended kinetic method ,microtiter plate kinetic method was established in the automatic enzyme immunoassay system of ALT detection .The linear ,intro‐batch and inter‐batch du‐plicability of the method were evaluated .ALT test results of 823 samples with microtiter plate kinetic method and automatic bio‐chemistry analyzer method were compared .Results Microtiter plate kinetic method had good linearity where ALT activity <303 U/L ,the intra batch and inter batch variation coefficients < 1/5TEa .The detection results of the clinical samples were correlated with the biochemical analyzer .Conclusion Microtiter plate kinetic method to detection ALT in the automatic enzyme immunoassay system is an ideal method for simultaneous detection of ALT and ELISA in large batch samples ,which is worth popularizing .
ABSTRACT
Objective To investigate thermal degradation kinetic characteristics of Cefmenoxime Hydrochloride in infusion solutions, and predict its thermal stability. Methods The HPLC was applied to determine the contents of Cefmenoxime Hydrochloride. Classical isothermal kinetic method and multivariate linear model were used to predict the expiration date of the injection. Results It was found that the thermal degradation kinetics of Cefmenoxime Hydrochloride in two infusion solutions corresponded with the first-order kinetics. The expiration dates of Cefmenoxime Hydrochloride in 0. 9%sodium chloride injection calculated by two different methods were 2. 20 days and 1. 52 days,and in 5% glucose injection were 2. 09 days and 1. 53 days,respectively. Conclusion The thermal stability of Cefmenoxime Hydrochloride in infusion solutions is poor and its expiration dates are the same calculated by two different methods.
ABSTRACT
Objective To develop an assay for determining bacterial endotoxin(BE T) content in Maodongqing Compound Injection (MCI). Methods The dilution radio o f Maodongqing Compound Injection was optimized and BET content was determined by turbidimetric kinetic method. Results Dilution ratio of Maodongqing Compound In jection at 1 ∶80 did not interfere with the Limulus test. The average recovery of BET was between 50 %and 200 %. Conclusion The method is proved to be accura te,sensitive and suitable for the determination of BET content in Maodongqing C ompound Injection.
ABSTRACT
Estudamos o mecanismo da reação de Jaffé para a determinação da creatinina humana, utilizando os métodos cinético e ponto-final. Foi analisada a magnitude de interferência nas constantes físicas (tempo e temperatura de incubação) e no equilíbrio da reação, obtendo-se valores subestimados a 25'C nos 2 métodos estudados. Os resultados a 30'C são coerentes com os valores de referência descritos na literatura. A hiperglicemia interfere mais significativamente na reação de ponto-final, elevando os resultados de creatinina a partir de 290 mg%. O método cinético mostrou-se bastante eficaz na dosagem da creatinina sérica discriminando valores sem interferência de substâncias redutoras e com reprodutibilidade compatível às melhores técnicas laboratoriais (AU).