Capillary Electrophoresis Sensitivity Enhancement Based on Adaptive Moving Average Method

Abstract

In the present work, we demonstrate a novel approach to improve the sensitivity of the "out of lab" portable capillary electrophoretic measurements. Nowadays, many signal enhancement methods are (i) underused (nonoptimal), (ii) overused (distorts the data), or (iii) inapplicable in field-portable instrumentation because of a lack of computational power. The described innovative migration velocity-adaptive moving average method uses an optimal averaging window size and can be easily implemented with a microcontroller. The contactless conductivity detection was used as a model for the development of a signal processing method and the demonstration of its impact on the sensitivity. The frequency characteristics of the recorded electropherograms and peaks were clarified. Higher electrophoretic mobility analytes exhibit higher-frequency peaks, whereas lower electrophoretic mobility analytes exhibit lower-frequency peaks. On the basis of the obtained data, a migration velocity-adaptive moving average algorithm was created, adapted, and programmed into capillary electrophoresis data-processing software. Employing the developed algorithm, each data point is processed depending on a certain migration time of the analyte. Because of the implemented migration velocity-adaptive moving average method, the signal-to-noise ratio improved up to 11 times for sampling frequency of 4.6 Hz and up to 22 times for sampling frequency of 25 Hz. This paper could potentially be used as a methodological guideline for the development of new smoothing algorithms that require adaptive conditions in capillary electrophoresis and other separation methods.

Optimization of a capillary zone electrophoresis–contactless conductivity detection method for the determination of nisin

“…Considering the separation conditions, the electro‐stacking effect was not the only measure that helped achieving superior LOQ for the CE methods described in the literature. Special data conditioning that filters out the noise in the electropherogram adaptively to the peak migration time was applied for the electropherograms . It was observed that S/N ratio increased 5.8 and 6 times for the nisin 1 and nisin 2 peaks correspondingly.…”

“…After analysis, vials containing BGE were replenished. The sensitivity of the analysis was enhanced using special data conditioning following the Migration Velocity Adaptive Moving Average method . Using this method, the peaks in the electropherograms are smoothed adaptively using optimal smoothing average window size.…”

“…Using this method, the peaks in the electropherograms are smoothed adaptively using optimal smoothing average window size. The method is capable of improving the LOQ up to 40 times .…”

Compensation of the baseline temperature fluctuations for autonomous CE–C4D instrument working in harsh environments

“…Some attempts to reduce thermal and electrical effects on the baseline fluctuations using differential C4D measurement were demonstrated . Computerized method based on migration velocity‐adaptive moving average method for improving the sensitivity of the developed system has been developed and applied . In C4D and conventional conductivity measurements, the reading depends on the temperature .…”

Design and applications of miniaturized, portable LED based colorimeter

“…The analysis that can be performed in situ provides several advantages: (i) reduces analysis errors due to the fact that sample transportation is not needed, and chemical degradation is avoided, and (ii) reduces the duration of the total analytical process [5]. Several chemical analyftical techniques have been applied, or are being developed for field-portable or autonomous applications: (i) liquid chromatography [6,7], (ii) capillary electrophoresis [8][9][10][11], (iii) digital microfluidics [12] and (iv) electrochemical analysis [13]. Designing portable or autonomous instruments can be problematic due to the following reasons: (i) such instrumentation has the limited battery power supply, (ii) a low number of mechanical and moving parts must be used in the design, and (iii) such instrumentation is susceptible to changing environment and especially temperature fluctuations [10,14].…”