Flow Innovation Research for Science and Technology Laboratories FIRST Labs

Thailand

Flow Innovation Research for Science and Technology Laboratories FIRST Labs

Thailand
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Chan-Eam S.,Flow Innovation Research for Science and Technology Laboratories First Labs | Chan-Eam S.,Mahidol University | Teerasong S.,Flow Innovation Research for Science and Technology Laboratories First Labs | Teerasong S.,King Mongkut's University of Technology Thonburi | And 4 more authors.
Talanta | Year: 2011

This work presents a new flow-based coupled electrochemical technique for evaluation of "total antioxidant capacity (TAC)". A sequential injection (SI) with amperometric detection was applied to the TAC analysis of commercial instant ginger infusion beverages using 2,2′-azino-bis(3- ethylbenzothiazoline-6-sulfonic acid) (ABTS) assay. Besides having chromogenic properties, the ABTS reagent behaves as an electroactive species at the glassy carbon electrode in phosphate buffer pH 7.0, the decrease of the cathodic current signal of the ABTS+ radical after reaction with antioxidants can be monitored. The SI system, furnished with an in-house electrochemical detection cell (ECD), was optimized with respect to the applied potential, sample and reagent volume, and flow rate to the detector. Gallic acid was used as the standard antioxidant and the capacity was reported as gallic acid equivalent (GAE) unit. TAC measurements of ginger infusions at the optimum condition were performed using the proposed technique and also with the classical batch spectrophotometric ABTS assay. TAC values obtained from our method and the standard method are in good agreement (r2 = 0.956). The SI-amperometric technique provided satisfactory precision (4.11% RSD) with rapid sample throughput (40 samples h-1). Also using this method, the consumption of the expensive ABTS reagent was greatly reduced. © 2011 Elsevier B.V. All rights reserved.


Henriquez C.,University of Sao Paulo | Maya F.,University of the Balearic Islands | Phansi P.,Flow Innovation Research for Science and Technology Laboratories FIRST labs | Phansi P.,Mahidol University | And 4 more authors.
TrAC - Trends in Analytical Chemistry | Year: 2016

Kinetic-catalytic analytical methods are simple and highly sensitive strategies for chemical analysis, that rely on simple instrumentation. For that reason, they have been implemented to the quantification of a large number of chemical species such as transition metals, non-metallic anions and organic compounds. Flow techniques are presented as an efficient tool to overcome the main limitations of the kinetic-catalytic methods. Solving problems related with sample handling, the reproducible data acquisition, reproducible temperature control and the implementation of different kinetic determination methods (initial rate, fixed time and fixed measure). Herein we review the recent applications of novel approaches to perform fully automated kinetic-catalytic methods based on computer controlled flow techniques. We also describe new devices and materials such as chip-based flow injection analyzers and the use of nanoparticles to improve the performance of this class of analytical methodologies. © 2016 Elsevier B.V.


Phansi P.,Flow Innovation Research for Science and Technology Laboratories FIRST Labs | Phansi P.,Mahidol University | Henriquez C.,University of the Balearic Islands | Palacio E.,University of the Balearic Islands | And 3 more authors.
Talanta | Year: 2014

In this work, the automation of a catalytic spectrophotometric method for the determination of molybdenum is presented. For this purpose, a multisyringe flow injection system was coupled to an integrated microconduit that we have called "chip". Reagents and sample were simultaneously dispensed to the chip where complete mixing, heating, and measurement were carried out. The spectrophotometric method is based on the oxidation of 4-amino-3-hydroxy- naphthalenesulphonic acid (AHNA) by hydrogen peroxide catalyzed by Mo (VI). Absorbance of the reaction product was measured at 465 nm. Two optical fibers were used to conduct the light, one from the source to the chip, and the other from the output of the cell to the spectrophotometer. The detection cell was incorporated in the thermostated zone of the chip. The initial rate method, at controlled temperature, was employed to determine the Mo (VI) concentration. The estimated precision was 3.7%, with the working range of 4.0-40 μg L -1 of Mo (VI), and the limit of detection of 1.2 μg L-1 of Mo (VI). The system was successfully applied to water samples and pharmaceutical products with a sampling throughput of 20 injections h -1. © 2013 Elsevier B.V.


Amatatongchai M.,Ubon Ratchathani University | Amatatongchai M.,Flow Innovation Research for Science and Technology Laboratories FIRST Labs | Laosing S.,Ubon Ratchathani University | Chailapakul O.,Chulalongkorn University | And 2 more authors.
Talanta | Year: 2012

An amperometric flow injection (FI) method suitable for evaluation of 'total antioxidant capacity' (TAC) is presented. In this method, a carrier stream of a solution of 2,2-diphenyl-1-picrylhydrazyl radical (DPPH •) continuously flows through an electrochemical cell, furnished with a carbon nanotube modified-glassy carbon electrode (CNT/GC) as the working electrode. At the applied voltage of 0.05 V (vs. Ag/AgCl), DPPH • is reduced resulting in a constant electric current. For measurement of the TAC, a sample zone containing antioxidant(s) is injected into the carrier stream therein reduction reaction of DPPH• occurring within the sample zone. The decreased amount of the radical in the sample zone leads to a drop of the amperometric signal at the CNT/GC electrode. We have also compared the performance of the CNT/GC electrode to the unmodified GC electrode using cyclic voltammetry. The sensitivity of the CNT/GC electrode was more than twenty five times greater than the bare GC electrode. The study of the sweep rate dependence showed that the cathodic and anodic current of 0.1 mM DPPH solution varied linearly (r2=0.998) with the square root of the scan rate, from 0.02 to 0.12 Vs-1. These results demonstrated that the CNT/GC electrode is appropriate for the quantitation of antioxidants via amperometric detection of the residual concentration of non-reacted DPPH •. We obtained linear calibrations for all the antioxidants tested including gallic acid, catechin, quercetin, caffeic acid and Trolox. The system offers rapid sample throughput (45 samples h-1) and good precision of 3.2% R.S.D., for 20 μL-injection of 2.5 μM Trolox (n=30). This method was applied to evaluate the TAC of extracts of some Thai indigenous vegetables. © 2012 Elsevier B.V. All rights reserved.


Teerasong S.,Mahidol University | Teerasong S.,Flow Innovation Research for Science and Technology Laboratories FIRST Labs | Chan-Eam S.,Flow Innovation Research for Science and Technology Laboratories FIRST Labs | Chan-Eam S.,Mahidol University | And 6 more authors.
Analytica Chimica Acta | Year: 2010

This work presents a new sequential injection analysis (SIA) method and a module for simultaneous and real-time monitoring of three key parameters for the beverage industry, i.e., the sugar content (measured in Brix), color and dissolved CO2. Detection of the light reflection at the liquid interface (the schlieren effect) of sucrose and water was utilized for sucrose content measurement. A near infrared LED (890±40nm) was chosen as the light source to ensure that all the ingredients and dyes in soft drinks will not interfere by contributing light absorption. A linear calibration was obtained for sucrose over a wide concentration range (3.1-46.5Brix). The same module can be used to monitor the color of the soft drink as well as the dissolved CO2 during production. For measuring the color, the sample is segmented between air plugs to avoid dispersion. An RGB-LED was chosen as the light source in order to make this module applicable to a wide range of colored samples. The module also has a section where dissolved CO2 is measured via vaporization of the gas from the liquid phase. Dissolved CO2, in a flowing acceptor stream of water resulting in the change of the acceptor conductivity, is detected using an in-house capacitively coupled contactless conductivity detector (C4D). The module includes a vaporization unit that is also used to degas the carbonated drink, prior the measurements of sucrose and color within the same system. The method requires no chemicals and is therefore completely friendly to the environment. © 2010 Elsevier B.V.


Phansi P.,Flow Innovation Research for Science and Technology Laboratories FIRST Labs | Phansi P.,Mahidol University | Henriquez C.,University of the Balearic Islands | Palacio E.,University of the Balearic Islands | And 5 more authors.
Analytical Methods | Year: 2014

In this work, we present an automated catalytic spectrophotometric method for determination of Mn(ii) by using a multisyringe burette coupled to a chip microfluidic-conductor (Chip-MSFIA). The reaction is based on the catalytic effect of Mn(ii) on the auto-oxidation reaction of succinimidedioxime (SIDO). Reagents and the sample were simultaneously dispensed to the chip for their complete mixing, heating, and measurement. The absorbance of the reaction product was measured at 700 nm. The product concentration could be determined by the fixed-time and the initial rate method under optimum conditions (temperature 35°C, 4.70 mmol L-1 SIDO, and 0.60 mol L -1 NaOH). Both fixed-time and initial rate methods have been developed, with the fixed-time method giving higher reproducibility and a wider working range. Therefore it was selected for Mn(ii) samples in the working range of 1-20 μg L-1 of Mn(ii). The estimated precision was 0.67% (5 μg L-1, n = 15) and the limit of detection of Mn(ii) was 0.33 μg L-1. The proposed method is highly sensitive, selective, and simple for trace Mn(ii) determination without extraction and separation steps. The system was successfully applied to water samples with an injection throughput of 22 injections h-1. © 2014 The Royal Society of Chemistry.


Phansi P.,Flow Innovation Research for Science and Technology Laboratories FIRST Labs | Phansi P.,Mahidol University | Henriquez C.,University of the Balearic Islands | Palacio E.,University of the Balearic Islands | And 3 more authors.
Analytical Methods | Year: 2014

In this work a fully automated catalytic-spectrophotometric method for determination of copper at trace levels using a multisyringe flow injection system (MSFIA) and a multipumping flow system (MPFS) coupled to a micro-chip (Chip-MSFIA-MPFS) is presented. The reaction is based on the catalytic effect of Cu(ii) on the oxidation of the in situ reduced form of 2,6-dichlorophenolindophenol (DCPI)r, by hydrogen peroxide. Due to the importance of the mixing order of the reagents, a new design of the chip is proposed. DCPI, ascorbic acid and buffer are first propelled to mix in the front section of the chip using MPFS. Then this reagent mixture, together with hydrogen peroxide and the sample, is simultaneously dispensed to the rear section of the chip by using a multisyringe for mixing, heating and absorbance measurement of the product at 600 nm. The optimum conditions are 0.9 mmol L-1 DCPI, 3.6 mmol L-1 ascorbic acid, 0.8 mol L-1 ammonium chloride buffer, pH 10.5, and 0.3 mol L-1 H2O2. The proposed system is simple, rapid, selective and sensitive. We can determine trace levels of Cu(ii) at room temperature (25 °C). The main analytical characteristics of the proposed method are a detection limit of 0.12 μg L-1 of Cu(ii), a working range of 0.4-35.0 μg L-1 of Cu(ii), and a relative standard deviation of 0.79% (10 μg L-1 Cu(ii), n = 15). The system was successfully applied to water samples, certified reference materials (CRMs) of river and waste water, acid digested multivitamins and animal tissues with a sample throughput of 31 injections h-1. This journal is © the Partner Organisations 2014.


Amatatongchai M.,Ubon Ratchathani University | Amatatongchai M.,Flow Innovation Research for Science and Technology Laboratories FIRST Labs | Sroysee W.,Ubon Ratchathani University | Chairam S.,Ubon Ratchathani University | And 2 more authors.
Talanta | Year: 2015

We report a novel amperometric glucose biosensor based on glucose oxidase (GOx) immobilized on a carbon nanotube (CNTs)-poly(diallyldimethyl-ammonium chloride) (PDDA)-platinum nanoparticle (PtNPs) modified carbon-paste electrode (CNTs-PDDA-PtNPs/CPE). The CNTs-PDDA-PtNPs composite materials were characterized by TEM and electrochemical techniques. Cyclic voltammetric results reveal direct electron transfer of the immobilized GOx, indicated by two quasi-reversible redox peaks at a potential of 0.37V (vs. Ag/AgCl) in phosphate buffered solution (PBS) (0.10M, pH 7). The biosensor provides good glucose oxidation activity and retention of GOx electrocatalytic activity due to CNTs-PDDA-PtNPs enhancement of the redox response. The carbon paste electrode was installed as working electrode in a flow through electrochemical cell of a flow injection (FI) system. Glucose was quantified using amperometric measurements at 0.5V vs. Ag/AgCl and PBS carrier (0.10M, pH 7.0) at a flow rate of 1.0mLmin-1. The linear working ranges for glucose measurements were 0.1-3mM (r 2=0.995) and 5-100mM (r 2=0.997), with corresponding sensitivities of 0.127 and 0.060 (μAs) mM-1, respectively. The system provides good precision of 2.8% R.S.D with a calculated detection limit (3S/N) of 15μM. The proposed method was successfully applied to determination of glucose in food and pharmaceutical samples with throughput of 200 samplesh-1. © 2015 Elsevier B.V.


Saetear P.,Flow Innovation Research for Science and Technology Laboratories FIRST Labs | Saetear P.,Mahidol University | Khamtau K.,Flow Innovation Research for Science and Technology Laboratories FIRST Labs | Khamtau K.,Mahidol University | And 6 more authors.
Talanta | Year: 2013

This work presents the simultaneous determination of sucrose and phosphate by using sequential injection (SI) system with a low cost paired emitter-detector diode (PEDD) light sensor. The PEDD uses two 890 nm LEDs. Measurement of sucrose in Brix unit was carried out based on the detection of light refraction occurring at the liquid interface (the schlieren effect) between the sucrose solution and water. Phosphate was measured from the formation of calcium phosphate with turbidimetric detection. With careful design of the loading sequence and volume (sample - precipitating reagent - sample), simultaneous detection of sucrose and phosphate was accomplished with the single PEDD detector. At the optimized condition, linear calibrations from 1 to 7 Brix sucrose and from 50 to 200 mg PO4 3- L-1 were obtained. Good precision at lower than 2% RSD (n=10) for both analytes with satisfactory throughput of 21 injections h-1 was achieved. The method was successfully applied for the determination of sucrose and phosphate in cola drinks. The proposed method is readily applicable for automation and is found to be an alternative method to conventional procedures for on-line quality control process in cola drink industry. © 2013 Published by Elsevier B.V.All rights reserved.


PubMed | Flow Innovation Research for Science and Technology Laboratories FIRST Labs
Type: | Journal: Talanta | Year: 2013

This work presents a new flow injection strategy, called cross injection analysis or CIA, an alternative cost-effective approach in flow analysis. The flow platform is made from a rectangular acrylic block, approximately 531.5 cm (xyz), with crossing cylindrical channels drilled out along the x- and y-axis of the block. The outlet from the single x-axis channel is connected to a detector flow cell. This channel is filled with the carrier solution. The flow in the x-axis channel is driven by a computer controlled single-channel peristaltic pump. The multiple y-axis channels, running perpendicular to the x-channel, are connected to a multi-channel peristaltic pump. These channels contain the sample and reagent solutions that flow across the intersection zones of the channels. To mix the sample and reagent with subsequent detection of the reaction zone, flow is applied along the x-axis channel, while flow in the y-axis channels is stopped. We successfully demonstrated the validity of the CIA technique by the spectrometric determination of Fe(II) using 1,10-phenanthroline and the speciation of Fe(II) and Fe(III). To place the CIA technique within the context of flow analysis, a brief overview of the evolution of flow injection analysis and its later innovative development is included.

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