Dual Flow Cell Research Articles

Application of electrochemical oxidation process to the degradation of the Novacron Blue dye using single and dual flow cells

The anodic oxidation of Novacron Blue (NB) has been studied by electrochemical measurements (cyclic voltammetry and polarization curves) and bulk electrolysis employing single flow cell (SFC) and dual flow cell (DFC), using Ti/Pt and Ti/Pt-SbSn as electrocatalytic materials. The results of voltammetries showed that with both anodes, in the potential region before oxygen evolution, the oxidation of NB involves simple electrode transfer, while a very different behavior was observed in the region of water decomposition. At the polarization curves, it was observed that Ti/Pt has lower activity due to lower production of hydroxyl radicals that destroy NB dye in solution, because it has a low overpotential for oxygen evolution and this secondary reaction is favored over mineralization. Conversely, Ti/Pt-SbSn showed significant electrocatalytic activity to oxidize NB. The results of bulk electrolysis showed that the use of SFC or DFC influences the elimination efficiency of color and dissolved organic matter. In the case of DFCTi/Pt+Ti/Pt-SbSn, after 5 h of electrolysis by applying 30 and 60 mA cm−2 at each one of the electrodes, complete color removal and ≈60 % of chemical oxygen demand (COD) elimination were obtained with lower energy consumption requirements when compared with the single electrochemical systems, SFCTi/Pt and SFCTi/Pt-SbSn.

A radio-high-performance liquid chromatography dual-flow cell gamma-detection system for on-line radiochemical purity and labeling efficiency determination

In this study, a method of determining radiochemical yield and radiochemical purity using radio-HPLC detection employing a dual-flow-cell system is evaluated. The dual-flow cell, consisting of a reference cell and an analytical cell, was constructed from two PEEK capillary coils to fit into the well of a NaI(Tl) detector. The radio-HPLC flow was directed from the injector to the reference cell allowing on-line detection of the total injected sample activity prior to entering the HPLC column. The radioactivity eluted from the column was then detected in the analytical cell. In this way, the sample will act as its own standard, a feature enabling on-line quantification of the processed radioactivity passing through the system. All data were acquired on-line via an analog signal from a rate meter using chromatographic software. The radiochemical yield and recovery could be simply and accurately determined by integration of the peak areas in the chromatogram obtained from the reference and analytical cells using an experimentally determined volume factor to correct for the effect of different cell volumes.

Use of a Dual Arrangement of Flow Cells for Electrochemical Decontamination of Aqueous Solutions Containing Synthetic Dyes

The present study was motivated by innovative reports published by De Battisti and co-workers (Martinez-Huitle et al., Electrochim Acta 50:949, 2004; Martinez-Huitle et al., J Appl Electrochem 35:1087, 2005) in 2004, on the electrochemical oxidation of chloroanilic and oxalic acids using electrolytic flow cell with parallel plate electrodes. These studies were few of the pioneering studies employing different design and configuration of electrochemical flow cells. Therefore, in this work, the applicability of single flow cell and dual flow cell (serial mode of SFC) systems was investigated for removing organic pollutants. Galvanostatic electrolyses were performed using the two electrochemical systems for degrading synthetic dye effluents (Remazol Red RB and Novacron Yellow), employing as electrocatalytic materials: Ti/Pt and Ti/Pt–SbSn. The electrochemical treatment of dye solutions led to complete discoloration and partial organic matter removal at different operating conditions (current density and flow cell configuration). The influence of these parameters was examined, in order to compare the use of single flow cell or dual flow cell, based on the energy consumption and costs. From the results obtained using dual flow cell configuration; higher color and organic matter removals were achieved in short times of electrolysis, confirming that this treatment process can be a suitable pre-treatment alternative for depuration of textile effluents decreasing the energy consumed when a single flow cell is employed.

The development and validation of a sensitive, dual-flow cell, SPR-based biosensor immunoassay for the detection, semi-quantitation, and characterization of antibodies to darbepoetin alfa and epoetin alfa in human serum

A surface plasmon resonance (SPR)-based biosensor immunoassay was developed and validated using the Biacore 3000 instrument to detect, semi-quantitate, and characterize serum antibodies against darbepoetin alfa (Aranesp ®) and epoetin alfa (EPOGEN ®). In this sensitive, dual-flow cell assay, epoetin alfa and darbepoetin alfa are covalently immobilized onto consecutive flow cells of a carboxymethyl dextran-coated sensor chip. Diluted human serum samples are injected sequentially over both surfaces. The binding of serum antibodies to the immobilized proteins are detected and recorded in real time based on the principles of SPR. Furthermore, antibody binding is confirmed with a secondary anti-human immunoglobulin antibody. Positive samples are further characterized to determine the relative concentration of the antibodies using an affinity-purified, rabbit anti-epoetin alfa antibody as a reference control. The assay can detect 80 ng/ml and 100 ng/ml of antibody to epoetin alfa and darbepoetin alfa, respectively. The dynamic range of the assay is from 0.078 μg/ml to 10 μg/ml using a rabbit antibody with demonstrated accuracy and intra- and inter-assay precision. Approximately 80 serum samples can be analyzed on each sensor chip while maintaining a stable baseline and consistent immunological reactivity. The analysis of serum samples from subjects administered with epoetin alfa or darbepoetin alfa provided evidence that the assay can detect varying concentrations of antibodies of different off rates, isotypes, and IgG subclasses.

Control of Oral Biofilm Formation by an Antimicrobial Decapeptide

Oral biofilms are mixed-species microbial communities, and their uncontrolled outgrowth can express as oral diseases. Antimicrobial peptides represent alternative classes of antimicrobials that exhibit selectivity for prokaryotes. We wanted to test the effect of a synthetic decapeptide antimicrobial, KSL, on the development of oral biofilms formed by isolated human salivary bacteria. We used differential interference contrast microscopy, coupled with a dual-flow cell system, to determine the effect of KSL on oral biofilm development. We used reductions of viable counts and confocal microscopy to assess the bactericidal activity of KSL on mature oral biofilms. KSL effectively blocked biofilm development. A significant effect on the viability of mature biofilms was observed when KSL was used in the presence of a surface-active agent, or after biofilms were mechanically disrupted. This study shows that KSL may be a useful adjunct for conventional oral hygiene to prevent plaque-mediated dental diseases.

1289 POSTER Ibandronate: an effective treatment for colorectal carcinoma patients with bone metastases

A surface plasmon resonance (SPR)-based biosensor immunoassay was developed and validated using the Biacore 3000 instrument to detect, semi-quantitate, and characterize serum antibodies against darbepoetin alfa (Aranesp®) and epoetin alfa (EPOGEN®). In this sensitive, dual-flow cell assay, epoetin alfa and darbepoetin alfa are covalently immobilized onto consecutive flow cells of a carboxymethyl dextran-coated sensor chip. Diluted human serum samples are injected sequentially over both surfaces. The binding of serum antibodies to the immobilized proteins are detected and recorded in real time based on the principles of SPR. Furthermore, antibody binding is confirmed with a secondary anti-human immunoglobulin antibody. Positive samples are further characterized to determine the relative concentration of the antibodies using an affinity-purified, rabbit anti-epoetin alfa antibody as a reference control.The assay can detect 80 ng/ml and 100 ng/ml of antibody to epoetin alfa and darbepoetin alfa, respectively. The dynamic range of the assay is from 0.078 μg/ml to 10 μg/ml using a rabbit antibody with demonstrated accuracy and intra- and inter-assay precision. Approximately 80 serum samples can be analyzed on each sensor chip while maintaining a stable baseline and consistent immunological reactivity. The analysis of serum samples from subjects administered with epoetin alfa or darbepoetin alfa provided evidence that the assay can detect varying concentrations of antibodies of different off rates, isotypes, and IgG subclasses.

Dual-response resonant chemical sensors for multianalyte analysis

We developed an approach to increase the information content from resonant, thickness-shear mode (TSM) sensors. These sensors are intended for integration into a microanalytical system that will periodically collect and precondition a predetermined volume of sample and will further present it to the sensor for analysis. Each side of the TSM resonator is coated with a different sensor film. During measurements, only one side at a time is exposed to an analyzed vapor while another side is exposed to a blank gas from a scrubber. Thus, analyte-related signals are generated independently from each side of the TSM sensor. Such dual-response sensing approach reduces the number of sensing elements by a factor of two, leading to further system miniaturization and improved power budget in sensor operation. We demonstrated our dual-response sensor concept with a high-performance, low noise TSM resonator ( f 0 = 10 7 Hz, RMS noise <0.05 Hz) arranged in a low volume (<200 μL) dual flow cell. With a single resonator, we successfully discriminated and quantified toxic industrial and environmental concern vapors such as toluene and trichloroethylene and two isomers of dichloroethylene (DCE) such as cis-1,2-DCE and trans-1,2-DCE.

Electrochemical detection of sulphide: a novel dual flow cell

A novel application of a dual flow electrochemical cell to the detection of hydrogen sulphide is presented. The sensor employs the electrochemically initiated reaction of N, N-dimethylphenylene-1,4-diamine (DMPD) with sulphide as the main analytical signal. The redox indicator is passed through one channel while sulphide effluent is flowed through the other with the streams separated by the use of a gas-permeable membrane. Preliminary results have shown that the sensor responds linearly to sulphide over the range 20–103 μM with the signal profile and response time capable of modulation through variation in the flow rates of the two streams.

Blanking system for the spectrophotometric determination of ammonia in surface waters

A reference stream is described for determining low levels (<0.5 mg l–1 as nitrogen) of ammonia in surface waters using an automated phenate-hypochlorite procedure including a dual flow cell spectrophotometer. The only difference between the reference and colour-formation streams is the replacement of the nitroprusside catalyst by an equal flow of water. The calibration graph for the system was linear, and the mean standard deviation for duplicate analyses of routine samples was 0.0023 mg l–1 as nitrogen for ammonia concentrations less than 0.080 mg l–1 as nitrogen. The correlation between this spectrophotometric procedure and an automated distillation-spectrophotometric procedure exceeded 99.9%, with the results for the automated distillation-spectrophotometric procedure being an average of 1% higher.