Showing papers on "pH meter published in 2000"
TL;DR: The retention of several compounds with acid/base behavior in a C-18 and a polymeric column with buffered methanol/water as mobile phase is related to the mobile phase pH value measured in the three pH scales, and it is demonstrated that the s(w)pH and s(s) pH scales give better relationships than the w(w]pH scale.
Abstract: The different procedures used in HPLC to measure the pH of a mobile phase are evaluated in terms of the rigorous IUPAC definition of pH. The three procedures evaluated are as follows: measurement of the pH of the aqueous HPLC buffer before mixing it with the organic modifier, measurement of the pH of the HPLC buffer after mixing it with the organic modifier using a pH electrode system calibrated with aqueous buffers, and measurement of the pH of the HPLC buffer after mixing it with the organic modifier but calibrating the electrode system with reference buffers prepared in the same mixed solvent used as mobile phase. Following IUPAC definitions and recommendations, the three pH values can be related with the pH scales: w(w)pH, s(w)pH, and s(s)pH, respectively. The relationships between these three pH scales are also presented. The retention of several compounds with acid/base behavior in a C-18 and a polymeric column with buffered methanol/water as mobile phase is related to the mobile phase pH value measured in the three pH scales. It is demonstrated that the s(w)pH and s(s)pH scales give better relationships than the w(w)pH scale (pH measured in the aqueous buffer before mixing it with the organic modifier), commonly used on HPLC. The s(w)pH scale is specially recommended because of its simplicity of measurement: the pH is measured after mixing the aqueous buffer with the organic modifier, but the pH calibration is performed with the common aqueous reference buffers.
171 citations
TL;DR: Potentiometric biosensors for the determination of organophosphorus (OP) insecticides were developed by applying either immobilized whole cells or cytoplasmic membrane fractions of wild-type Flavobacterium sp.
Abstract: Potentiometric biosensors for the determination of organophosphorus (OP) insecticides were developed by applying either immobilized whole cells or cytoplasmic membrane fractions of wild-type Flavobacterium sp. on the surface of a glass pH electrode. The ability of Flavobacterium sp. to degrade OP compounds as sole carbon source was demonstrated for parathion with a degradation rate of almost 100% after 30 min and for chlorpyrifos of 33% after 48 h incubation. The products of hydrolysis of these compounds, p-nitrophenol and 3,5,6-trichloro-2-pyridinol, were accumulated in the medium and not used as substrates for growth by Flavobacterium sp. In the course of hydrolysis, which is catalyzed by organophosphorus hydrolase, two protons are released for each substrate molecule hydrolyzed. This stoichiometry forms the electrochemical basis of the potentiometric biosensors. Direct determination without previous extraction of OP was carried out in a stirred measuring cell with a pH electrode as transducer. Poly(carbamoyl sulfonate) (PCS) prepolymer, a hydrogel with good adhesive properties, was used for immobilization of whole cells and membrane-associated organophosphorus hydrolase. The sensor with cytoplasmic membrane fractions was superior to the one with whole cells and showed a linear range for paraoxon from 0.01 to 0.47 mM and 3 weeks' working stability.
49 citations
TL;DR: Sodium addition to a Na-free glass ionomer confirms the role of this cement in enhancing pH change in NaF solution and indicates that F-/OH- interchange is not a significant mechanism even when anion/cation uptake is not balanced.
29 citations
TL;DR: In this paper, a coulometric diffusional titrator with a ruthenium dioxide pH-sensing electrode for the end-point detection in acid-base titrations is presented.
27 citations
TL;DR: The application of an optical sensor based on immobilization of the ruthenium complex [Ru(bpy)2(dhphen)]2+ in Nafion to pH monitoring of fermentation by Klebsiella pneumoniae is described.
17 citations
TL;DR: In this article, a series of field experiments was carried out in both pools in which the pH electrodes were permanently fixed just above the surface of the mats, and the whole electrode assembly was shielded from waves and wind by a cylindrical metal.
Abstract: A further series of field experiments was carried out in both pools inwhich the pH electrodes were permanently fixed just above the surface of the mats. The whole electrode assembly was shielded from waves and wind by a cylindrical metal The pH measurements for the experiments were carried out using a small portable pH meter and a gel-filled combined glass/reference electrode. The pH meter was calibrated between buffers of pH 4 and 7 and the electrode put into position before each measurement.
9 citations
TL;DR: In this article, two new air gap sensors with different indicator electrodes for the determination of nitrogen oxides and nitrites are described, and the linear range of the electrode functions E −f(−lg[NO2]) and E −mV(−mg[NaNO2]), for the sensor on the base of a combined glass pH electrode was 5.5mV in both cases.
8 citations
TL;DR: In this article, a remote sensing system was used to monitor pH and temperature in two freshwater ponds in Southeastern Massachusetts from 1990 to 1993 using a remote-sensing system that collected data on a continuous basis.
7 citations
TL;DR: In this paper, the inhibition effect of the ions Pb2+, Fe2+, Sn2+, Zn2+ and Hg2+ toward the urea-sensitive biosensor was investigated.
Abstract: The biosensor, which determines the variation of the pH as a consequence of the hydrolysis process of urea, is composed of a biological receiver (the urease) and a potentiometric sensor (a metallic pH electrode, tungsten). Keeping in mind that the sensitivity of the sensor changes depending with the inhibitor concentration for urease (which is present in the water or in the soil), this could be used to determine the degree of pollution of the surface waters and of the soil. In this way it would be possible to establish the quantities of the urea utilized as chemical fertilizer.
In the present work, we present the investigation of the inhibition effect of the ions Pb2+, Fe2+, Sn2+, Zn2+ and Hg2+ toward the urea-sensitive biosensor. The determinations with samples of surface waters and soils in the presence of 10−1 M urea and one-minute contact time has demonstrated the possibility of monitoring the concentrations of these ions in the following domains: 10−2–10−6 M Fe2+; 10−2–10−6 M Zn2+; 10−4–10−6 M Pb2+. These limiting values are found if the cation is individually present. © 2000 John Wiley & Sons, Inc. Lab Robotics and Automation 12:27–30, 2000
6 citations
Patent•
27 Jan 2000
TL;DR: In this article, a transition metal-based sensor electrode adapted to provide an equilibrium potential and an inert reference electrode to provide a baseline voltage or current, which sensor and reference electrodes are physically separated; and a baseline means adapted to impose a baseline potential between the sensor and the reference electrodes.
Abstract: Apparatus, suitable for use as an electrochemical sensing device, comprising: a) a transition metal-based sensor electrode adapted to provide an equilibrium potential; b) an inert reference electrode adapted to provide a baseline voltage or current, which sensor and reference electrode are physically separated; and c) baseline means adapted to impose a baseline potential between the sensor and reference electrodes, whereby the baseline voltage or current may be set, is disclosed. Also disclosed is the use of the apparatus as a pH meter.
3 citations
Patent•
29 Feb 2000
TL;DR: In this paper, a disposable BUN sensor is provided with a pH electrode which is formed on an insulating film to detect pH changes, an enzyme layer which is provided on the pH electrode and comprises a mixture of an enzyme, a water-swelling high polymer material, a surfactant, a buffer material and the like and a filter layer, which is required to prevent the spillage of the enzyme from the enzyme layer and restrict the diffusion of urea and nitrogen, to remove cross substance in a measurement liquid.
Abstract: PROBLEM TO BE SOLVED: To provide a disposable 'BUN' sensor and a production method thereof, which enable detection of pH changes, using a pH electrode at lower cost, and moreover along with a shorter measurement time and a higher measuring accuracy. SOLUTION: The disposable BUN sensor is provided with a pH electrode which is formed on an insulating film to detect pH changes, an enzyme layer which is provided on the pH electrode and comprises a mixture of an enzyme, a water-swelling high polymer material, a surfactant, a buffer material and the like and a filter layer, which is provided covering the enzyme layer to prevent the spillage of the enzyme from the enzyme layer and restricts the diffusion of urea and nitrogen, to remove cross substance in a measurement liquid. In the production method of the disposable BUN sensor, an electrode layer is formed by a screen printing method on a polyethylene film and the pH electrode, the enzyme layer and the filter layer are formed separately in a drip drying process.
Patent•
12 Sep 2000
TL;DR: In this paper, the authors proposed a method to reduce the used quantity of rinsing water while complete washing can be performed by injecting gaseous CO2 and/or carbonated water to water used in a riningsing process.
Abstract: PROBLEM TO BE SOLVED: To reduce rinsing time and the used quantity of rinsing water while complete washing can be performed by injecting gaseous CO2 and/or carbonated water to water used in a rinsing process. SOLUTION: In a washing method in which water and acidic, alkaline detergents are alternately fed and pre-washing, washing, and rinsing processes are performed in this order, a device for injecting gaseous CO2 and/or carbonated water into water used in the rinsing process is arranged. This device is provided with pH meters 1 and 2, a gaseous CO2 cylinder, a line mixer, a liquid transfer pump, and a heat exchanger. The pH meter 1 is installed at a waste water outlet of a washing object device shown as a production line to check pH of waste water, and for example, if pH becomes 8-9.5, the termination of washing is detected to stop the injection of gaseous CO2 by control equipment. The pH meter 2 monitors the variations in pH of water into which gaseous CO2 is injected to agitate and mix them by a line mixer and into which gaseous CO2 is blow and checks its abnormality occurrence (such as, the gaseous CO2 cylinder becoming empty).
TL;DR: In this paper, the inorganic ion concentrations and pH were analyzed using an ion chromatogram and a pH electrode respectively, showing that the correlation coefficient between pH and inorganic ions was high.
Abstract: The purpose of this study was to know the range of fluctuation of inorganic ion concentrations and pH in the unstimulated whole saliva and also to know if there is individual difference between subjects which surpasses this fluctuation. Whole saliva was collected seven times between 9 AM and 4 PM at one- or two- hour intervals from ten subjects aged 24 to 27 years. The inorganic ion concentrations and pH were analyzed using an ion chromatogram and a pH electrode respectively. The coefficients of variation of the inorganic ion concentrations were between 24% to 43%, indicating that it is misleading to interpret only one data obtained as the true value of the subject. However, statistical analysis showed that the pH value and inorganic ion concentrations were significantly different among many of the subjects, in spite of the fluctua tion within individual subjects. On the other hand, most of the correlations were statistically significant among pH and each of the inorganic ions. Above all, the correlation coefficient between potassium and phosphate ion concentrations was high. In contrast, the sodium ion did not have any significant correlation with most of the other ions. The results were discussed in reference to the salivary secretion mechanism.
Patent•
15 Feb 2000
TL;DR: In this article, a packed tower filled with granular calcium carbonate is used to adjust pH of fluorine-containing waste water in order to remove fluorine from waste water.
Abstract: PROBLEM TO BE SOLVED: To fluorine make effectively removable with a packed tower filled with granular calcium carbonate by surely adjusting pH of fluorine-containing waste water SOLUTION: PH in a storage tank 10 is measured with a pH meter 12, and an addition of a pH adjusting agent is controlled and the pH is roughly neutralized A fluorine concentration in the treated water from the granular calcium carbonate filled tower 22 is measured, then the pH of inflow water into the packed tower filled with granular calcium carbonate 22 is adjusted By adjusting the pH in two stages, the reaction in the granular calcium carbonate filled tower 22 is always maintained appropriately
Patent•
23 Jun 2000
TL;DR: In this paper, a molding for pH measurement is provided, by which the pH measurement of pore water in a trace amount, in a compacted substance difficult to measure by a pH meter and a sheet of pH testing paper in conventional cases, can be performed simply and effectively.
Abstract: PROBLEM TO BE SOLVED: To provide a molding, for pH measurement, by which the pH measurement of pore water, in a trace amount, in a compacted substance difficult to measure by a pH meter and a sheet of pH testing paper in conventional cases, the pH measurement of a solution containing much sludge, filth, suspension or the like and the pH measurement under a high-temperature and high-humidity condition can be performed simply and effectively and to provide a method in which a pH value can be measured by using the molding. SOLUTION: Coloring particles in which a pH indicator is adsorbed to adsorbent particles are sealed up inside a protective sheet which is composed of a dialytic membrane, and a molding for pH measurement is obtained. The molding for pH measurement is left as it is in an object to be measured. After that, the coloring particles inside the protective sheet are taken out. A pH value is found on the basis of a change in the color of the coloring particles. Preferably, the change in the color of the coloring particles is measured by a colorimeter as a reflectance, and a pH value corresponding to the reflectance is found on the basis of a reflectance-pH value working curve which is created in advance.
Patent•
4 May 2000TL;DR: In this paper, an undivided electrolysis cell was used for treating dredged material contaminated with organometallic compounds, and an independent claim was also included for the plant used in the above process.
Abstract: Treating dredged material and other products contaminated with organometallic compounds comprises suspending the product in process water, activating the process water electrochemically by electrolysis and adjusting the pH by the current density applied to the electrodes in an undivided electrolysis cell. An Independent claim is also included for the plant used in the above process comprising an undivided electrolysis cell, in which the process water is activated electrochemically and the product is treated, and a pH meter.
Patent•
22 Feb 2000
TL;DR: In this paper, an acid is added in an adequate amount to the pumped water to adjust the pH to 4-6, and the obtained acidic water is returned to the surface layer of the reservoir to make the pH of the surface-layer water neutral or weak acidic in the process of mixing diffusion.
Abstract: PROBLEM TO BE SOLVED: To prevent the deterioration in environment of water area caused by mass generation of algae to preserve the environment of the water area and carry on a life cycle under moderate existence of algae which are ones of important living things constituting the environment of the water area. SOLUTION: High-temperature surface layer water of a reservoir is pumped up by a storage pump 1, an acid is added in an adequate amount to the pumped water to adjust the pH to 4-6, and the obtained acidic water is returned to the surface layer of the reservoir to make the pH of the surface layer water neutral or weak acidic in the process of mixing diffusion. For adding the acid, the pH of the surface layer is measured with a pH meter 6, and an acid amount adjusting device 3 consisting of a pump or a valve is controlled by a signal from a pH controller 2 to supply the acid to a mixing tank 4 in which the acid is mixed with the water.
Patent•
7 Jan 2000TL;DR: In this paper, the pH bias is reduced by utilizing the discovery that the presence of protein in a liquid sample induces an apparent interference with the pH value, which is known as pH bias.
Abstract: The present invention provides a means to substantially decrease the pH bias that is commonly observed with pH data obtained using ion selective electrode (ISE) containing instruments that have a solvent polymeric membrane based ISE pH electrode. The pH bias is reduced by utilizing the discovery that the presence of protein in a liquid sample induces an apparent interference with the pH value.
Patent•
20 Jun 2000
TL;DR: In this paper, a two-phase type anaerobic biological treatment method and apparatus where acid formation and methane formation are separated is proposed. But this method requires the use of a pH meter to measure the pH in an acid forming tank and when the measured value is lowered to a predetermined value or less, a part or the whole of return treated water to a methane forming tank 2 is returned to the acid-forming tank 1 to hold the interior of the acid tank to the optimum pH range.
Abstract: PROBLEM TO BE SOLVED: To provide an efficient two-phase type anaerobic biological treatment method and apparatus wherein acid formation and methane formation are separated. SOLUTION: Measurement of pH in an acid forming tank 1 is made by a pH meter 4 and, when the measured value is lowered to a predetermined value or less, a part or the whole of return treated water to a methane forming tank 2 is returned to the acid forming tank 1 to hold the interior of the acid forming tank 1 to the optimum pH range.
Patent•
7 Jan 2000TL;DR: In this article, the pH bias is reduced by utilizing the discovery that protein induces an apparent bicarbonate ion concentration ([HCO3-]) interference, which can be corrected by a single equation using the available (HCO?3?-]) value.
Abstract: The present invention provides a means to substantially decrease the pH bias that is commonly observed with pH data obtained using ion selective electrode (ISE) containing instruments that have a solvent polymeric membrane based ISE pH electrode. The pH bias is reduced by utilizing the discovery that protein induces an apparent bicarbonate ion concentration ([HCO3-]) interference. The pH bias has also been found to vary as a function of protein loading. Additionally, this protein-induced bias in membrane-based pH sensors was found to be relatively constant in the normal protein range (typically ranging from about 4 to about 8 g/dl) such that the total pH bias in this protein range is a function of ([HCO?3?-]). Thus, in the normal protein range, the pH bias can be corrected for by a single equation using the available ([HCO?3?-]) value.
TL;DR: Ability of glass-ionomers to increase pH is likely to be an important mechanism of caries protection under clinical conditions because the extent and speed of the change in pH are similar to that of active caries in vivo.