Amperometric detection (AD) For more see journals 109. Amperometric detection (AD) is the widely reported electrochemical detection technique in capillary electrophoresis, flow analysis, and liquid chromatography [Art. No. 108]. This technique carried out by supplying a constant potential to the working electrode and resulting current measured as a function of time. At the surface of the working electrode, the redox reaction of the analytes takes place by the application of potential, whereas output current is proportional to the analytes concentration. Furthermore, the response of current is directly proportional to the number of analyte moles that oxidize or reduce at the working electrode surface as given by Faraday’s law: I_t=dQ/dt=nF dN/dt where I_t is the yield current at working electrode surface at given time t, Q is the charge at the working electrode surface, t is is the time, n is the number of electrons transferred per mole of analyte, F is the Faraday constant (96485 C/mol), and N is number of moles of analyte oxidized or reduced [33: Art. No. 101]. Advantages There are some unique advantages make amperometric technique more popular such as higher sensitivity, very good selectivity in the direction of electroactive compounds, simple instrumentation easy to handle and economical [Art. No. 105], minimal contribution of background current, and easy to operate [Art. No. 108]. Voltammetry For more see
PH sensors are used in many scientific laboratories to measure the hydrogen-ion concentration of a liquid substance and to determine the basicity and acidity of a liquid. PH meters measure the electrical potential difference between a reference electrode probe and a pH electrode probe. Since these probes are very sensitive, they are required to be kept cleansed from contaminants. If exposed to contamination, one risks faulty or unreliable data, since their accuracy is dependent on a regular calibration and upkeep. To avoid this risk, and accurately measure hydrogen-ion concentration, the probes are kept in a buffer solution and calibrated before each use. [1]
Chemical interference is relatively low due to the use of chemical modifiers to stabilize the analyte and make the matrix more volatile; hence, it contributes in further improvement to the sensitivity of this technique. However, the technique has some disadvantages like:- (1) limited working range, (2) slow analysis, and (3) high cost (Harvey, D. 2010).
Which one of the statements concerning valence bond (VB) and molecular orbital (MO) bond theories is correct?
1. We measured 2 mL of diluted hydrogen peroxide (the substrate), 1 mL of guaiacol (the product indicator), and 1 mL of neutral buffer (pH 7) with a syringe and disposed it into tubes 1, 2 , 4, 9, 11, and 12.
The diagram below shows a labelled circuit which is used for the experiment. This is set up by collecting all equipment needed and attaching the DC power supply to the ammeter with a wire this is all connected to the anode and cathode with a red and black wire to differentiate between the two electrodes. The two electrodes are shown to be placed in a beaker of copper sulphate
PH sensors are used in many scientific laboratories to measure the hydrogen-ion concentration of a liquid substance and to determine the basicity and acidity of a liquid. PH meters measure the electrical potential difference between a reference electrode probe and a pH electrode probe. Since these probes are very sensitive, they are required to be kept cleansed from contaminants. If exposed to contamination, one risks faulty or unreliable data, since their accuracy is dependent on a regular calibration and upkeep. To avoid this risk, and accurately measure hydrogen-ion concentration, the probes are kept in a buffer solution and calibrated before each use. [1]
AAS has contributed to the understanding of elements having different absorption emission spectra due to their difference in energy levels. In the absorption spectrum, the absorbed light are shown as black gaps. As the number of electrons increase, the number of spectral lines also increase. Hence, by measuring the absorption of light, the concentration of the element within a sample can be determined. By knowing the concentrations of an element, scientists are now aware that even the smallest amount can make a significant impact towards the biological system. Therefore, scientists have brainstormed ways to monitor the use of chemicals in the
Into the SPE cartridge added 1 ml of methanol and aqua bides with the help of a vacuum (conditioning steps), added 1 ml of plasma was spiked with OFX concentration (0.10, 0.25, 1.00, 2.00, 3.00, 4.00 5.00, and 6.00, μg/ml), each concentration contained CFX 3μg/ml (loading steps). Added 1 ml 5% methanol (washing steps), eluted analysts with 20% acetonitrile 1ml in phosphate buffer (eluting steps). Analytics was injected into the HPLC using optimize condition, then the efficiency of extraction of SPE is calculated by comparing the area under curve (AUC) between SPE and without SPE chromathograms for same
A hot plate was preheated to 100°C. A dry 5-mL long-neck round-bottom flask was clamped over an aluminum block placed on the hot plate. Ferrocene (0.09 g), acetic anhydride (0.35 mL), and 85% phosphoric acid was added to the flask in that order of addition. A magnetic stir bar was added to the flask. Solution was stirred and heated for 10 minutes. Flask was removed and allowed to cool to ambient temperature. DI water (0.5 mL) was added and the solution was cooled to 0°C by ice bath. The solution was neutralized with 3M sodium hydroxide dropwise while stirring and cooling. PH was monitor by pH indictor paper. Solid product was isolated by vacuum
From the data recorded, a curve is produced. The potentiometric titration curve method tends to be more accurate than the color indicator method; however, the curve method is more time intensive and is not always suitable
The potentiostat was set up by the instructor with acetate buffer. The sample was deaerated with nitrogen gas for 5 to 8 minutes in order to remove oxygen. Oxidation and
Incorporation of assay controls included setting up a spectrophotomer and running the chart recorder with a full-scale deflection before the start of the assay. The set recorder had a corresponding value of 1 for the change in the absorbance. Therefore, prior testing was done to observe whether a change occurred in the readings. This helped to indicate that the results were valid, as they could have been affected by a fault during the setting up of the spectrophotometer. On the other hand this was considered as one of the controls for the experiment. Nevertheless, a new cuvette had to be used for each assay.
In order to test the hypothesis that the WRKY75 transcription factor directly regulates FLS2 expression, electrophoretic mobility shift assay (EMSA), the CRISPR/Cas9 and microarray techniques can be implemented. Firstly, an EMSA will be conducted to determine whether WKRY75 is a transcriptional factor that regulates and binds to pFLS2. The DNA probe that will be used is the pFLS2 double-stranded DNA sequence, which contains the regulatory element. WRKY75 will be determined as a binding protein if we observe band shift, as electrophoresis separates molecules based on charge and size; therefore, DNA attached to a protein will take longer to migrate through the gel. If WRKY75 is determined to be a transcriptional factor of pFLS2, we can implement the CRISPR/Cas9 technique.
Electrophoresis is the method of separation of charged molecules based on different migration in an electric field. Applicable features of the electrophoresis technique such as high effectiveness, high resolving power, high speed, fully automation and a variety of injection based pre-concentration schemes and detection modes have all been broadly examined. (Tavares, et al., 2003). It is a developed systematic and micro preparative instrument. The method provides faster separations, at higher resolution and with greater separation efficiencies (Swerdlow & Gesteland, 1990). Capillary electrophoresis has applications in several areas like clinical/forensic, cosmetological, environmental, nutritional and pharmaceutical. (Tavares, et al., 2003). For forensic applications it has exceptional separating power, rapid analysis times, and high mass sensitivity, in terms of reagents and consumables, requiring only least quantities of sample (Tagliaro, Pascali, & Lewis, 2013)
This reports looks into the measurement techniques used in electrophysiology (patch clamp in particular) and how those developed over the years. The difference between the intracellular (inside the cell) and extracellular (outside the cell) measurements is highlighted and the examples of each are given. The technology used to make the measurements is examined (including the commercial examples of Q-Patch and IonFlux) and a microcontroller implementation is suggested. A microcontroller can be used to amplify the signal and measure the current and capacitance of the equivalent circuit to reduce the computational workload on the computer or it can simply be used as a signal generator. The current research in the electrophysiology and the electrophysiology measurement field was also looked at (using High Density Surface EMG for more applications, using EMG and NIRS together to help diagnose and monitor Duchenne Muscular Dystrophy in children).