Faculty of Chemistry and Chemical Engineering, University of Maribor, Smetanova ulica 17, 2000 Maribor, Slovenia.
Biosensors (Basel). 2021 Aug 19;11(8):285. doi: 10.3390/bios11080285.
This work demonstrates the analysis of epinephrine (EP) and uric acid (UA) in a single drop (the volume of the test solution was only 50 µL) using a screen-printed carbon electrode (SPCE) sensor and square-wave voltammetry (SWV). The limit of detection, limit of quantification, linearity, accuracy, precision, and robustness were validated. The normality of the experimental data was tested and confirmed for both methods. Heteroscedasticity was checked by residual analysis followed by a statistical -test. The latter was confirmed for both analytes. The low relative standard deviations (RSD) at all calibration points and repetitive slopes justified the use of a calibration curve; therefore, the standard addition methodology was avoided (the latter is common in electroanalysis, but time-consuming). Since the conditions for using an ordinary least squares (OLS) regression were not met, weighted linear regression (WLR) was used to improve the accuracy of the analytical results at low concentrations of the analytes. In this manner, the best weighted model was determined and used for the quantification. A comparison was made between the OLS and WLR methods to show the necessity of using the WLR method for EP and UA analysis. The newly developed and validated methods were also shown to be effective in the analysis of real samples. The content of EP in an EP auto-injector and UA in human urine was tested by employing the best weighted model. For EP and UA, the accuracy in terms of the average recovery value was 101.01% and 94.35%, and precision in terms of RSD was 5.65% and 2.75%, respectively. A new analytical methodology is presented that uses a low volume (a single drop), and it offers the advantage of electroanalysis for on-site analysis, where conventional chromatographic techniques cannot be easily employed. Furthermore, the developed technique has additional advantages in terms of speed, cost, and miniaturization.
本工作展示了使用丝网印刷碳电极（SPCE）传感器和方波伏安法（SWV）在单个液滴（测试溶液体积仅为 50µL）中分析肾上腺素（EP）和尿酸（UA）的方法。验证了检测限、定量限、线性、准确度、精密度和稳健性。对两种方法的实验数据的正态性进行了检验和确认。通过残差分析和统计检验检查异方差性。两种分析物均得到了证实。在所有校准点和重复性斜率下，相对标准偏差（RSD）均较低，证明可以使用校准曲线；因此，避免了标准添加法（后者在电分析中很常见，但耗时）。由于不满足使用普通最小二乘法（OLS）回归的条件，因此使用加权线性回归（WLR）来提高分析物低浓度下分析结果的准确性。通过这种方式，确定了最佳加权模型并用于定量。比较了 OLS 和 WLR 方法，以说明在 EP 和 UA 分析中使用 WLR 方法的必要性。还展示了新开发和验证的方法在实际样品分析中的有效性。通过使用最佳加权模型，测试了 EP 自动注射器中的 EP 含量和人尿中的 UA 含量。对于 EP 和 UA，平均回收率值的准确度分别为 101.01%和 94.35%，RSD 的精密度分别为 5.65%和 2.75%。提出了一种新的分析方法，该方法使用小体积（单个液滴），并且具有电分析的优势，可用于现场分析，而常规色谱技术不易采用。此外，所开发的技术在速度、成本和小型化方面具有额外的优势。
