A comparison of concentration measurement techniques for the estimation of the apparent mass diffusion coefficient

Abstract

In this article we compare two different techniques to measure the concentration of saline solutions for the identification of the apparent mass diffusion coefficient in soils saturated with distilled water. They are the radiation measurement technique and the electrical conductivity measurement technique. These techniques are compared in terms of measured quantities, sensitivity coefficients with respect to unknown parameters and the determinant of the information matrix. The apparent mass diffusion coefficient is estimated by utilizing simulated measurements containing random errors. The Levenberg-Marquardt method of minimization of the least-squares norm is used as the parameter estimation procedure. The effects of the volume of saline solution injected into the column devised for the experiments on the accuracy of the estimated parameters are also addressed in this article

Stress Biomarkers in Biological Fluids and Their Point-of-Use Detection

“…±50%), but in many cases the reported range can vary by more than an order of magnitude. In select cases, the biomarker concentration is known to vary during the 24 h cycle, with cortisol and DHEA (dehydroepiandrosterone) being two such examples. , It is also likely that the biomarker type and concentration detected can be partially dependent on measurement technique, the condition of the instrumentation, and sample extraction and condition. , For example, the concentration of cortisol in sweat detected using ELISA is generally reported in the range of 8–142 ng/mL. However, measurements using HPLC-MS have reported a considerably lower concentration range .…”

“…39,40 It is also likely that the biomarker type and concentration detected can be partially dependent on measurement technique, the condition of the instrumentation, and sample extraction and condition. 41,42 For example, the concentration of cortisol in sweat detected using ELISA is generally reported in the range of 8−142 ng/mL. However, measurements using HPLC-MS have reported a considerably lower concentration range.…”