Evaluation of the vant'Hoff's osmotic coefficient in concentration polarization conditions of membrane system

In this paper the method of evaluation the value of osmotic vant't Hoff's coefficient (f) in membrane system, which is based on the original equation of third degree for the coefficient f was elaborated. This equation, obtained on the basis of Kedem-Katchalsky equation, contains the transport parameters of membrane (Lp, sigma, omega), solution concentration (C), volume flux (Jvm), thickness of concentration boundary layer (delta), etc. These parameters can be determined in a series of independent experiments. The calculation performed for the solution of ammonia in aqueous solution of KCl and polymer membranes show that, the value of coefficient f fulfill the condition 1 < or = f < or = 2 and that there is a range of concentrations of ammonia, in which the changes f occur nonmonitically     

Thermodynamical description of the concentration polarization in a membrane transport of non-electrolyte solution

An expression for concentration polarization coefficient (chi) was derived from Kedem-Katchalsky equations. This expression contains the volume flux (Jvm), transport parameters of a membrane (omega m) and concentration boundary layers (omega 1, omega h). Calculations performed using the obtained expression showed that for a polymeric membrane with fixed transport properties, coefficient chi is a nonlinear function of concentration difference of solutions. This nonlinearity is related to the appearance of the convection instability that breaks symmetry of the l(h)/M/l(l) complex in relation to the gravitational direction.     

Application of the network thermodynamics to interpretation of membrane transport: evaluation of the resistance coefficients of the polymeric membrane in polarization concentration conditions

The Kedem-Katchalsky equations, derived using symmetric transformation of the Peusner's network transformation, to interpretation of transport through Nephrophan membrane of glucose aqueous solutions in concentration polarization conditions were employed. The values of Rij* (i does not equal j = 1, 2) coefficients were calculated. From these calculations it results that, the values of coefficients R11*, R12* = R21* and R22* are nonlinear dependent as well as on concentration of solutions (C) and configuration of membrane system.     

Application of the network thermodynamics to interpretation of membrane transport: evaluation of the L(ij) coefficients of the polymeric membrane in polarization concentration conditions

The Kedem-Katchalsky equations, derived using symmetric transformation of the Peusner's network, to interpretation of transport through Nephrophan membrane of glucose aqueous solutions in concentration polarization conditions were employed. The values of L(ij)* (i, j = 1, 2) coefficients were calculated. From these calculations it results that, the value of coefficient L(11)* is constant, while values of the coefficients L(12)* = L(21)* and L(22)* are dependent as well as on concentration of solutions (C) and configuration of membrane system.     

Application of the Peusner's network thermodynamics to interpretation of the passive membrane transport of binary non-electrolytic solution: evaluation the P(ij) coefficients of polymeric membrane in polarization concentration conditions

In this paper the Kedem-Katchalsky equations were derived, using hybrid transformation of Peusner's network. These equations were applied to interpretation of a transport through polymeric membrane of binary nonelectrolyte solutions under concentration polarization conditions. The values of coefficients P(ij)* (i, j = 1, 2) were calculated for Nephrophan membrane and aqueous glucose solutions. From the calculations it results that the coefficient values P(11)*, P(12)*, P(21)* and P(22)* are nonlinear depend on a solution concentration (C) and configuration of the membrane system. Moreover, the values of coefficients P(11)*, P(12)*, P(21)* and P(22)* were compared to the values of coefficients H(11), H(12), H(21) and H(22), calculated for conditions of solution homogeneity for the same values C and varied configurations of membrane system. It is shown that a threshold value exists and when exceeded, coefficients relations P(11)*/P(11), P(12)*/P(12) and P(22)/P(22) depend on a configuration of the membrane system.     

Time evolution of NaCl flux through the microbial cellulose membrane with concentration polarization

The method of solute permeability coefficient and solute fluxes appointment for the membrane, based on monitoring of changes of conductivity of electrolyte solutions was presented. It was stated that during mechanical stirring of solutions the coefficient of NaCl permeability for microbial cellulose membrane (Biofill) did not depend on configuration of the membrane system and concentrations of solutions. Time characteristics of NaCl flux through the membrane Biofill oriented in horizontal plane were measured and modeled. The changes of NaCl fluxes through the membrane Biofill caused by concentration boundary layers build up on both sides of the membrane depended on NaCl concentrations and configuration of the membrane system. The differences between fluxes in different configurations of the membrane system were observed after time depended on initial concentrations in chambers. After that time, for configuration with solution with higher density over the membrane (configuration B) the NaCl flux through the membrane was greater than for configuration with solution with lower density over the membrane (configuration A). Besides it was stated that the coefficient of concentration polarization for configuration B was higher than for configuration A for all studied NaCl concentrations. Increase of mean concentration in the membrane at the initial moment caused increase (for configuration B) and lack of changes (for configuration A) of concentration polarization coefficient in the steady state of the membrane system. The interpretation of experimental results was made on the basis of Kedem-Katchalsky equations for the membrane system.     

Canalicular membrane transport is primarily responsible for the difference in hepatobiliary excretion of triethylmethylammonium and tributylmethylammonium in rats.

Two structurally similar quaternary ammonium compounds, triethylmethylammonium (TEMA, M(r) 116) and tributylmethylammonium (TBuMA, M(r) 200) were used as model compounds to identify the unit process of hepatobiliary excretion that is responsible for markedly different biliary excretion of organic cations (OCs). Cumulative biliary excretion (in percentage of dose; i.v., 12 micromol/kg) was 0.17 for TEMA and 34.5 for TBuMA. In vivo uptake clearance into the liver was 0.686 +/- 0.020 ml/min for TEMA and 0.421 +/- 0.028 ml/min for TBuMA. When the uptake clearance was examined in an isolated hepatocyte system, comparable clearance between TEMA and TBuMA was obtained, consistent with the in vivo result. These observations suggest that uptake into the liver is not the major determinant for the difference in biliary excretion of the OCs. Coadministration of colchicine, an inhibitor of microtubule formation, had no effect on biliary excretion of the model compounds, and the primary site of subcellular distribution of the OCs appears to be the cytosol, suggesting that intracellular movement does not play a major role in the markedly different biliary excretion of the OCs. In contrast, in vivo excretion clearance across the canalicular membrane for TBuMA was 180-fold greater than that for TEMA, and in vitro efflux clearance of TBuMA was smaller than that of TEMA (p <.01), indicative of involvement of these processes in the markedly different biliary excretion of the OCs. Therefore, these data indicate that canalicular transport is primarily responsible for the markedly different biliary excretion of TEMA and TBuMA.     

The effect of the hydrogen ion concentration on membrane transport of dissociated drugs from saturated solutions

Dissociating drugs diffuse from saturated solutions with suspended drug particles across lipophilic membranes according to zero order kinetics. The highest rate is maintained even if large fractions of the drug are dissociated due to the pH-conditions of the solution. The pH range of the highest and pH-independent membrane transport corresponds with drug solubility/pH-profiles, showing the solubility of the undissociated drug.     

Effects of concentration boundary layers in a transport of electrolyte solutions through horizontal mounted polymeric membrane

The results of experiment of diffusive transmembrane transport in a single-membrane osmotic-diffusive electrochemical cell were presented. In all experiments one of the vessels was filed with pure water, and the second one--with aqueous potassium chloride solution in aqueous ammonia solutions of constant concentration. The flux of potassium chloride was assigned according to the following measure procedure. In a first step we assigned the time dependence of potassium chloride flux in conditions of uniform mechanically stirred solution with speed of 500 rpm. In a second step those characteristics were assigned in conditions of mechanically unstirred solution. Each experiment was made for two configurations of gravitational membrane system: (i) with the water in a vessel above the membrane and solution below it (configuration A) (ii) with the solution in a vessel above the membrane and water below it (configuration B). Taking under the consideration the values of potassium chloride flux in steady state for different solution concentration of the same substances and the same configurations of membrane system, the dependencies of potassium chloride flux from the solution concentration differences were made appropriately. On the base of those experiments the solute flux concentration boundary layers effects (jCBLE) were counted. Moreover it was shown that single-membrane osmotic-diffusive electrochemical cell has rectifier and amplifying of diffusive flow features. The coefficients, appropriately, of asymmetry and amplification of diffusive flux are the measurements of those features.     

高效液相色谱法测定顺铂注射液的含量

目的采用高效液相色谱法测定顺铂注射液中顺铂的含量。方法以Hypersil NH2 色谱柱 ,0 .1%NaCl溶液为流动相 ,流速为 0 .8ml/min ,顺铂和反铂的保留时间分别为 3.37和 5 .5 1min ,检测波长为 2 10nm、最低检测限为 6ng。结果标准曲线的线性范围为 10 0 .0 4～ 30 0 .12 μg/ml(r=0 .9997) ,方法回收率为 99.0 7% ,RSD为 0 .5 4 %。结论此法可用于直接测定顺铂注射液中顺铂的含量     

HPLC法测定异环磷酰胺血药浓度方法的改进

目的建立以甲醇-水为流动相测定异环磷酰胺血药浓度的方法,以降低治疗药物监测的成本.方法用氯仿萃取血清中的异环磷酰胺,浓集后进样测定.在室温条件下,使用ELITE C18色谱柱(250 mm×4.5 mm,5μm),以甲醇-水(1:1,v/v)为流动相,以咖啡因为内标,检测波长200 nm.结果本方法线性范围10～200 mg·L-1,相关系数0.999 2,最低检测浓度5.2 mg·L-1,回收率94%～103%.结论该方法灵敏度较高、准确度较好、操作简便,适用于对异环磷酰胺进行治疗药物监测,并且成本较低.     

荧光偏振免疫法测定血中依替米星的浓度

目的:探索应用荧光偏振免疫法测定依替米星血药浓度的实验方法,考察该方法测定依替米星的可行性.方法:使用庆大霉素荧光偏振免疫试剂盒,用TDx对依替米星进行测定.结果:本方法能够检测依替米星的血药浓度,回归曲线为Y=0.439X+0.1772,r=0.9981,在0.5～20μg·mL-1,浓度范围内线性关系良好.日内、日间标准偏差均小于10%,低、中、高不同浓度的加样回收率分别为(93.12～9,74)%,(102.41～2.73)%,(89.50～1.45)%.结论:本方法灵敏度高,操作简便,检测时间短,可以用于临床快速检测依替米星的血药浓度.     

Quantifying processes determining the free concentration of phenanthrene in Basal cytotoxicity assays

Difficulties may arise when extrapolating in vitro derived toxicity data to in vivo toxicity data because of the high variability and occasional low sensitivity of in vitro results. Differences in the free concentration of a test compound between in vitro and in vivo systems and between different in vitro systems may in part explain this variability and sensitivity difference. The aim of this study was to determine what assay components influence the free concentration of phenanthrene in a Balb/c 3T3 and RTgill-W1 MTT assay. Partition coefficients of phenanthrene to serum, well plate plastic, cells, and headspace were measured and subsequently used to model the free concentration of the compound in vitro. The estimated free concentration was compared to the free concentration measured in the assays using solid phase microextraction (SPME). Results indicate that the free concentration of phenanthrene, a relatively volatile and hydrophobic compound, is significantly reduced in a typical in vitro setup as it binds to matrices such as serum protein and well plate plastic. A reduction in free concentration due to increasing serum protein levels is accompanied by an increase in the median effect concentration (EC(50)) and can be modeled, with the exception of evaporation, using the partition coefficients of the compound to assay components.     

Mathematical model of the membrane transport of ternary non-electrolyte solutions: the role of volume flows in creation of concentration boundary layers

The mathematical model of the thickness of concentration boundary layers controlling by concentration Rayleigh number and volume flows for ternary non-electrolyte solution was presented. The equations determining of this model can be used to numerical calculations.     

心肌磷酸腺苷的高效液相色谱测定条件的优化

目的：优化心肌样品中的磷酸腺苷的高效液相色谱法测定条件。方法：固定其他色谱条件,改变流动相组成与配比,以分离结果的优劣优化流动相。结果：甲醇－水（2：98）（含0．15mol/L磷酸二氢钠,pH=6.0)为局部最佳流动相条件。结论：本条件可以实现该样品的准确、快速、经济实用的分析。