USE OF VISCOMETER FOR MONITORING PURITIES OF CLINICAL SOLUTIONS

Abstract

The activation energy, E_a of an original pure liquid should change when a solute molecule is added to it since the addition may change the bond strength of the given liquid molecule as the impurity (solute) molecules tend to occupy the neighboring positions in the liquid. The change in E_a is expected to be affected significantly by addition of impurity molecules and thus the viscosity coefficient and the time of flow of the mixture through a capillary tube. Monitoring purity level (concentration levels) of clinical intravenous fluids is very important for safety of patients. In this paper we study using a simple viscometer the viscosity coefficients of clinical Dextrose and Sodium Chloride solutions. We find that the viscosity, at 30.5⁰C, of dextrose solution with concentration range from 2.0% to 20.0%  varied from 8.71 x 10^-4Pa.s to 13.32 x 10^-4Pa.s  within an error of   ±0.1%. For sodium chloride solution with concentration range from 1% to 10%, viscosity coefficient varied from 8.91 to 10.41x10^-4 Pa.s. With distilled water as a standard and using the concept of reduced time ratio of flow and the observed data, we find that the viscometer can be very reliably used to measure concentration of any unknown clinical Dextrose and Sodium Chloride solutions. From the measured data we also determine the positive changes of activation energy of the two types solutions with increase in solute concentrations. We recommend further measurements at three different temperatures which shall enable us to determine the absolute values of the activation energies of the two solutions of different concentrations. We present necessary theoretical analysis so that with the data, any viscometer can then be used as a reliable liquid purity(Dextrose and Sodium Chloride solutions) analyzer. The data can also be used to study variation of molecular properties of solutions with concentrations of solute. The latter studies can find applications in solution chemistry.

Key words: Viscometer, Concentration, Activation energy, viscosity coefficient, clinical solutions, reduced time ratio.