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The first detailed examination of non-aqueous capillary electrophoresis with electrochemical and electrochemiluminescence detections (NACE-EC/ECL), separation parameters and their interactions via central composite design was presented. This concept was demonstrated by examining the optimization separation conditions of seven antihistamines (chlorpheniramine, cyproheptadine, diphenhydramine, doxylamine, methapyrilene, terfenadine, and triprolidine) by NACE-EC/ECL. To evaluate the NACE separation quality, the chromatography resolution statistic function (CRS(-1) function) with regard to the resolution and migration time was established as the response variable. The influences of three experimental variables (buffer apparent pH value (pH*), buffer (TBAP) concentration, and separation voltage) on the response were investigated. A set of optimal conditions was obtained from central composite design: 9.2 mM TBAP in ACN (pH* 4.0) and voltage (12.7 kV), and under these optimum conditions, the seven antihistamines could be well separated in less than 10 min. The obtained electropherograms indicated that the dual EC/ECL detection system was indispensable since the six antihistamines (except for triprolidine) displayed both EC and ECL response, whereas triprolidine only displayed the EC response. This work is instructive for investigators in simplifying the NACE-EC/ECL development procedures for multi-component analysis.

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The presence of gaseous elemental mercury (GEM) in the atmosphere has raised concern because it can cause serious health effects. The largest anthropogenic source of atmospheric mercury in the Philippines is the artisanal small-scale gold mining (ASGM) sector, which accounts for about 30% of the country's annual mercury discharge. There is therefore a need for a portable monitoring system for GEM that can be employed in the ASGM areas. In this study, a gold thin film electrode was used as chemiresistor mercury sensor. Interaction of mercury with the gold thin film produced changes in the resistance of the film that were dependent on the amount of mercury present. These changes can be monitored through the output voltage of the Wheatstone bridge circuit that was incorporated in the sensor. The surface of the thin film can be regenerated through thermal desorption of the adsorbed mercury. It is capable of detecting Hg vapor levels from 0 to 30 ng with good linearity (r = 0.9975) and with a detection limit of 1.77 ng. It yielded repeatable results as demonstrated for 10 ng Hg with rsd value of <10%. A prototype measurement system for gaseous elemental mercury based on this sensor was assembled.

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Introduction Dengue fever is the major public health concern in the Philippines and is endemic in all regions of the country in which all serotypes are present[1]. Despite the widespread nature of the virus transmitted by mosquitos, molecular diagnostics have significant limitations. An early diagnosis of dengue may prevent severe clinical complications associated with the infection. A novel genosensor using an aptamer for the detection of dengue virus serotypes 1-4 was demonstrated in this study. Method This genosensor composed of a thiolated aptamer immobilized on a 10MHz gold electrode QCM targeting the 3’ untranslated region of all complete genome sequences of dengue virus available in GenBank[2]. Aptamer concentration, buffer pH and ionic strength of buffer solutions were optimized to achieve the highest sensitivity of the QCM genosensor. Atomic force microscopy [3], electrochemical impedance spectrum (EIS) measurements and cyclic voltammetry (CV) were used to characterize the surface of the QCM electrode prepared[4]. Evaluation of binding kinetics and affinity study of the Aptamer-dengue genome was determined by surface plasmon resonance (SPR)[5]. Results and Conclusions Atomic Force Microscopy (AFM), Electrochemical Impedance (EIS) and Cyclic Voltammetry (CV) have been used to characterize the surface of the PQC electrode. The AFM results indicate that the thiolated aptamer onto the electrode has decreased the roughness of gold surface by forming a uniform layer on the electrode surface. The EIS and CV results indicate that the charge transfer resistance is increased after immobilization of the aptamer onto the bare gold electrodes, indicating that direct S-Au bonding via disulfide moieties and the negative charge of protein have blocked the electrode reaction between Fe (II) and Fe (III). The results showed that the developed aptamer QCM sensor has an optimum concentration range of the target dengue genome is 20–100 mg/ml for hybridization. This work demonstrated the possibility of using an immobilized aptamer on a QCM and other sensor platforms for the direct detection of the RT-PCR products of dengue virus serotypes 1-4. References [1] A.A. de los Reyes, J.M.L. Escaner, Dengue in the Philippines: Model and analysis of parameters affecting transmission, J. Biol. Dyn. 12 (2018) 894–912. doi:10.1080/17513758.2018.1535096. [2] E. Alm, B. Lesko, G. Lindegren, C. Ahlm, S. Söderholm, K.I. Falk, N. Lagerqvist, Universal Single-Probe RT-PCR Assay for Diagnosis of Dengue Virus Infections, PLoS Negl. Trop. Dis. 8 (2014) 6–15. doi:10.1371/journal.pntd.0003416. [3] X. Zhang, V.K. Yadavalli, Surface immobilization of DNA aptamers for biosensing and protein interaction analysis, Biosens. Bioelectron. 26 (2011) 3142–3147. doi:10.1016/j.bios.2010.12.012. [4] A.-E. Radi, Electrochemical Aptamer-Based Biosensors: Recent Advances and Perspectives, Int. J. Electrochem. 2011 (2011) 1–17. doi:10.4061/2011/863196. [5] E. González-Fernández, N. De-Los-Santos-Álvarez, A.J. Miranda-Ordieres, M.J. Lobo-Castañón, SPR evaluation of binding kinetics and affinity study of modified RNA aptamers towards small molecules, Talanta. 99 (2012) 767–773. doi:10.1016/j.talanta.2012.07.019. Figure 1