Stability of simulated body fluids such as blood plasma, artificial urine and artificial saliva

Abstract

The cause of this publication was the problem with the reproducibility of the earlier results conducted with using simulated body fluids. After the exclusion of other factors, the suspicion fall on SBF liquids, which as proved by this publication, in many cases were unstable.Simulated body fluids, such as artificial blood plasma, artificial urine and artificial saliva, are an important testing environment to predict e.g. a potential bone-bonding behavior through the apatite layer formation on its surface; for drug delivery systems examination or osteoinductive material properties. Consequently, it is necessary to ensure constant pH, constant ionic strength and undisturbed access to the calcium (and phosphate) in an artificial body fluids. Therefore, pH value were measured in this work by using pH meters (from two companies) and ion concentrations (Na+ and Ca2+) by using inductively coupled plasma – mass spectrometry (ICP-MS) and atomic absorption spectroscopy (AAS).The result of the work is answer to the question concerning the stability of the tested liquids. All tested simulated body fluids incubated at 36°C above the week demonstrated changes in pH and ion concentration. The largest change was observed with calcium ions which plays a crucial role in the hydroxyapatite growth during the artificial blood plasma application. Furthermore only in a few cases storage of fluids at 5°C did not significantly affected their stability.