Compromise in uncertainty estimation by modelling and validation approaches for an HPLC-UV method for measurement of biochemical indicators of vitamins A and E

Abstract

It is common practice nowadays to associate the measurement uncertainty to the measurand, in order to judge the quality of a result related to the measurement process. However, the improvement of this parameter as well as the adaptation of its estimation modes always remain an analytical challenge, especially in chemical testing. In this paper, we outline a measurement uncertainty estimation mode based on the one-point linear calibration equation to fully establish a "bottom-up" approach for estimating the measurement uncertainty of a multi-point calibration-based HPLC-UV quantitative method. To demonstrate this estimation mode, we have followed as an example of interest the influences resulting from the simultaneous determination of two biochemical indicators, namely the human plasma vitamers retinol and α-tocopherol. Results from this estimation showed consistency when compared to those obtained from the validation-based alternative method, where the relative expanded uncertainties were found, at a 95% confidence level, to be less than 15% for the low concentration ranges of the two molecules. However, the modelling approach shows all the benefits of its use to identify and quantify all the uncertainty contributions arising from the different steps of the analytical process and seems to be quite achievable for comparative HPLC methods.

Study of the effect of feeding two cultivars of purslane (Portulaca oleracea l.) On lipid profile and lipid peroxidation of adult male Sprague Dawley rats

“…This indicated that both wild and cultivated purslane exerted a positive effect on decreasing elevated serum cholesterol levels by 22% and 23% in wild and cultivated purslane, respectively. Similar results were obtained by other authors (Djellouli et al, 2018(Djellouli et al, , p. 1492Lee et al, 2011, p. 202). In this study, purslane was added to a level of 2.5 % to both test groups leading to decreased total cholesterol level in the blood.…”