An Advanced Statistical Approach Using Weighted Linear Regression in Electroanalytical Method Development for Epinephrine, Uric Acid and Ascorbic Acid Determination

Abstract

In this study, the use of weighted linear regression in the development of electrochemical methods for the determination of epinephrine (EP), ascorbic acid (AA), and uric acid (UA) is presented. The measurements were performed using a glassy carbon electrode and square-wave voltammetry (SWV). All electroanalytical methods were validated by determination of the limit of detection, limit of quantification, linear concentration range, accuracy, and precision. The normal distribution of all data sets was checked using the quantile-quantile plot and Kolmogorov-Smirnov statistical tests. The heteroscedasticity of the data was tested using Hartley’s test, Bartlett’s test, Cochran’s C test, and the analysis of residuals. The heteroscedastic behavior was observed with all analytes, justifying the use of weighted linear regression. Six different weighting factors were tested, and the best weighted model was determined using relative percentage error. Such statistical approach improved the regression models by giving greater weight on the values with the smallest error and vice versa. Consequently, accuracy of the analytical results (especially in the lower concentration range) was improved. All methods were successfully used for the determination of these analytes in real samples: EP in an epinephrine auto-injector, AA in a dietary supplement, and UA in human urine. The accuracy and precision of real sample analysis using best weighted model gave satisfactory results with recoveries between 95.21–113.23% and relative standard deviations between 0.85–7.98%. The SWV measurement takes about 40 s, which makes the presented methods for the determination of EP, AA, and UA a promising alternative to chromatographic techniques in terms of speed, analysis, and equipment costs, as the analysis is performed without organic solvents.

Selective Voltammetric Detection of Ascorbic Acid from Rosa Canina on a Modified Graphene Oxide Paste Electrode by a Manganese(II) Complex

“…The relative standard deviation was measured at two levels of concentration mass of AA, i.e., 45 μg L −1 and 158 μg L −1 and calculated to be 4.2 % and 3.8%, respectively, values indicating the good reproducibility of the proposed assay. The linear detection region of AA in the present study is in several cases better than that determined by the corresponding electrochemical techniques in the literature [ 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 45 ] On the other hand, the detection limit of the current analytical AA detection methodology is better compared to the majority of those determined with the other corresponding electrochemical techniques available in the literature, with the exception that it is in the same magnitude of Zhao et 2019 [ 20 ], Kaçar and Erden 2020 [ 2 ], Broncová et al 2021 [ 34 ], Pekin et al [ 45 ], as it can be seen from Table 1 .…”

“…Meanwhile, for the electrochemical determination of AA, electrodes with modified surfaces have been widely used, overlapping the fulling effect due to oxidation that may occur on the conventional electrode surfaces [ 6 ]. Carbon paste (CPE) [ 12 , 19 ] and glassy carbon (GCE) [ 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 ] modified electrodes are the most commonly used for AA analysis in the available literature. Moreover, Pt modified electrodes with 3,4-diaminobenzoic acid and neutral red [ 34 ] or screen-printed electrodes (SPE) [ 35 , 36 , 37 ].…”

Pla-Peg-Cholesterol Biomimetic Membrane for Electrochemical Sensing of Antioxidants

“…The redox behaviour of such molecules were already studied in previous works by using different electrodes and electrolyte solutions. [51,52] For instance, Sempionatto et al [53] have described the detection of dehydroascorbic acid (i.e. the oxidized compound of AA) by fabricating an epidermal patch sensor for nutrition regulation.…”

Single-Drop Analysis of Epinephrine and Uric Acid on a Screen-Printed Carbon Electrode

“…Analysis of EP and UA can be performed using high-performance liquid chromatography [23,24], gas chromatography [25,26], spectrophotometry [27,28], capillary electrophoresis [29][30][31], and electroanalytical methods [32][33][34][35][36]. The advantages of electroanalytical methods for EP and UA determination, compared to the above techniques, are high sensitivity, the low cost of analysis and instrumentation, and a fast analysis time [22,37].…”