scholarly journals ELECTROMETRIC TITRATION OF CHLORIDE IN SMALL VOLUMES

1955 ◽  
Vol 32 (4) ◽  
pp. 822-829 ◽  
Author(s):  
J. A. RAMSAY ◽  
R. H. J. BROWN ◽  
P. C. CROGHAN
Keyword(s):  
Standard Deviation ◽  
Silver Nitrate ◽  
Biological Fluids ◽  
Silver Electrode ◽  
End Point ◽  
Other Substances ◽  
Electrometric Titration ◽  
In Series ◽  
A Current

1. Two methods of titrating chloride with Ag+ ion using the potentiometric end-point are described. 2. The first method is conventional in that silver nitrate is added from a burette. It deals with volumes down to 0.2µl. and can measure 1µg. of chloride with an error of < ± 1% (standard deviation). 3. According to the second method Ag+ ion is added by passing a current through a silver electrode in series with a condenser. The charge developed on the condenser is a measure of the amount of chloride titrated. This method deals with volumes down to 0.5 x 10-3µl. and can measure 10-4µg. of chloride with an error of < ± 1% (standard deviation). 4. As far as is known these methods are not susceptible to interference from other substances likely to be present in biological fluids.

scholarly journals Simultaneous Determination of Sodium and Potassium in Small Volumes of Fluid by Flame Photometry

1953 ◽  
Vol 30 (1) ◽  
pp. 1-17
Author(s):  
J. A. RAMSAY ◽  
R. H. J. BROWN ◽  
S. W. H. W. FALLOON
Keyword(s):  
Standard Deviation ◽  
Simultaneous Determination ◽  
Biological Fluids ◽  
Ammonium Phosphate ◽  
Flame Photometry ◽  
Limits Of Detection ◽  
Other Substances ◽  
Lower Limits ◽  
Sodium And Potassium

1. A method of flame photometry is described, by which the amount of sodium and potassium in biological fluids can be determined simultaneously, using samples of the order of 10-3 cu.mm. 2. When the method is tested with quantities near the lower limits of detection (of the order 4 x 10-8 mg. sodium, 6 x 10-8 mg. potassium) the reproducibility, measured as standard deviation, is ±7 x 10-9 mg. sodium and ± 17 x 10-9 mg. potassium. 3. When larger quantities (up to certain limits) are used, the standard deviation is approximately ± 3 % of the quantity in the sample, both for sodium and for potassium. 4. As is usual in flame photometry serious errors can be caused by the presence of other substances in the sample. In the case studied for purposes of illustration it is shown that these interference errors can be reduced to the order of ± 6 % by the addition of excess ammonium phosphate.

scholarly journals Investigation of changes in the characteristics of LED matrices of the on-board luminaire during tests in the electrocycling mode.

2021 ◽  
Author(s):  
I.V. Frolov ◽  
◽  
V.A. Sergeev ◽  
A.M. Hodakov ◽  
S.A. Zaytsev ◽  
...  
Keyword(s):  
Leakage Current ◽  
Direct Current ◽  
Coefficient Of Variation ◽  
Convection Heat Transfer ◽  
Voltage Range ◽  
The Matrix ◽  
Operating Current ◽  
In Series ◽  
The Difference ◽  
A Current

The paper presents the results of studies of changes in the characteristics of LED COB matrices of the GW P9LR31.EM - DURIS S 8 type as part of a LED luminaire when tested under the direct current in a continuous mode and in an electrocycling mode. The arrays consist of eight InGaN/GaN LED dies connected in series, coated with a phosphor. Calculation in the Comsol Multiphtsics environment of the temperature field of the luminaire at the rated operating current and free convection heat transfer showed that the maximum overheating of the matrices does not exceed 46 K, and the difference in their temperatures is 2 K. At the same time, the experimental values of the thermal resistances of the matrices of a real lamp vary from 42 to 58 K/W. Before testing, the I-V characteristics of the matrices differ markedly in the level of leakage current in the voltage range from 14 V to 19 V, and the LEDs in the luminaire matrices have a significant spread in the brightness of emission in the microcurrent mode. The degree of this scatter within each matrix was estimated by measuring the luminescence brightness of each die of the matrix and calculating the coefficient of variation γ. It was found that the coefficient of variation of the emission brightness of the COB matrix dies measured at a current of 100 nA strongly correlates with the leakage current. When testing a luminaire under the direct current, the most significant changes in the electrophysical and optical characteristics of COB matrices are observed in the range of microcurrents: the distribution of the emission brightness of the matrix dies at a current of 100 nA becomes more uniform. The greatest changes in matrix characteristics were observed after the first 700 hours of testing, that is, at the running-in stage. At the same time, no correlation was found between the degree of change in the characteristics of the matrices during tests and their thermal resistances.

A New Saccharogenic Micromethod for Measurement of Amylase Activity in Biological Fluids

1970 ◽  
Vol 16 (4) ◽  
pp. 300-304 ◽  
Author(s):  
Klaus Lorentz ◽  
Detlef Oltmanns
Keyword(s):  
Standard Deviation ◽  
Blood Donors ◽  
Serum Amylase ◽  
Amylase Activity ◽  
Biological Fluids ◽  
Soluble Starch ◽  
Starch Digestion ◽  
Triphenyltetrazolium Chloride ◽  
Serum Amylase Activity ◽  
Apparently Healthy

Abstract To determine serum amylase activity we have quantitatively measured the glucose and maltose hydrolyzed from soluble starch by colorimetrically measuring the reduction of colorless triphenyltetrazolium chloride to a red formazan, which is dissolved in methanol. The method is suitable for use with microsamples of all biological fluids, and is specific for the final products of starch digestion. Values found for sera from 55 apparently healthy blood donors ranged from 0.15 to 1.55 (mean, 0.83; standard deviation, ±0.4) mg of glucose per ml per h, corresponding to 7.5 to 78 Somogyi units.

Potentiometric Determination of Chlorides in Wine, Distilled Spirits, and Wine Vinegar

1966 ◽  
Vol 49 (3) ◽  
pp. 498-501
Author(s):  
Clifford E Hubach
Keyword(s):  
Silver Nitrate ◽  
Collaborative Study ◽  
Potentiometric Determination ◽  
End Point ◽  
Direct Titration ◽  
Distilled Spirits ◽  
Wine Vinegar ◽  
High Degree

Abstract Collaborative study of the Pro method for determining chlorides in wines and distilled spirits by direct titration with silver nitrate followed by potentiometric reading of the end point gave accurate and reproducible results. The procedure is suitable for repetitious analyses in control laboratories, and it is also adaptable to determinations requiring a high degree of precision. Recoveries of chloride added to samples averaged 99.7%. The method is recommended for adoption as official, first action.

Volumetric Determination of Malathion, Using Dichlorofluorescein as Indicator

1976 ◽  
Vol 59 (1) ◽  
pp. 216-218
Author(s):  
Miguel Siquiroff ◽  
Ricardo Pollero ◽  
Rodolfo Goyena
Keyword(s):  
Standard Deviation ◽  
Petroleum Ether ◽  
Silver Nitrate ◽  
Ethyl Ether ◽  
Colorimetric Method ◽  
Florisil Column ◽  
Average Recovery ◽  
Florisil Column Chromatography ◽  
Volumetric Determination

Abstract A method has been developed which is based on alkali cleavage of malathion and volumetric determination of the resulting dimethylphosphorodithioate with silver nitrate, using dichlorofluorescein as the indicator. Pure malathion standards were analyzed by the proposed method, yielding a standard deviation of 0.27. Four typical malathion formulations containing talc, wheat flour, and anionic and nonionic emulsifiers were analyzed by both the proposed method and the former official first action colorimetric method with comparable results. Potential interferences from surfactants currently employed in liquid formulations are avoided by the use of Florisil column chromatography. Malathion is eluted from the column with petroleum ether-ethyl ether with an average recovery of 92.5%.

ACTIVE-FEEDBACK SINGLE MILLER CAPACITOR FREQUENCY COMPENSATION TECHNIQUES FOR THREE-STAGE AMPLIFIERS

2010 ◽  
Vol 19 (07) ◽  
pp. 1381-1398 ◽  
Author(s):  
MOHAMMAD YAVARI
Keyword(s):  
Low Power ◽  
Small Signal ◽  
Frequency Compensation ◽  
Gain Bandwidth ◽  
Silicon Area ◽  
Active Feedback ◽  
In Series ◽  
Unity Gain ◽  
Simulation Results ◽  
A Current

This paper presents two novel active-feedback single Miller capacitor frequency compensation techniques for low-power three-stage amplifiers. These techniques include the active-feedback single Miller capacitor frequency compensation (AFSMC) and the dual active-feedback single Miller capacitor frequency compensation (DAFSMC). In the proposed techniques, only one Miller capacitor in series with a current buffer is utilized. The main advantages of the proposed three-stage amplifiers are the enhanced unity-gain bandwidth and the reduced silicon area. Small-signal analyses are performed and the design equations are obtained. Extensive HSPICE simulation results are provided to show the usefulness of the proposed AFSMC and DAFSMC amplifiers in both large and small capacitive loads.

scholarly journals Load Characteristics with Current Detection Using an Arduino Based ACS712 Sensor

2020 ◽  
Vol 2 (2) ◽  
pp. 83
Author(s):  
Nur Ratnawati ◽  
Sunardi Sunardi
Keyword(s):  
Circuit Complexity ◽  
Current Sensor ◽  
Test Results ◽  
Analog To Digital ◽  
In Series ◽  
Current Measuring ◽  
Current Monitoring ◽  
Current Detection ◽  
A Current ◽  
Peak Value

This study discusses tools for digital current monitoring using an Arduino-based ACS712 sensor. The current sensor ACS712 5A uses the principle of hall effect and is a current sensor whose circuit complexity is simple. The purpose of this microcontroller is to read data obtained from the sensor using the Analog to Digital Converter (ADC) feature and then display it in the serial monitor. The ATMEGA328 microcontroller is assisted by a current measuring circuit equipped with a sensor mounted in series against the circuit to be measured in order to measure the current flowing in the circuit. The test results show that the sensor can measure the current value at its peak value with an error value of -0.066 and a standard deviation value of 0.011419. Based on the test results it can be seen that the tool can work well and has a good accuracy rate.

scholarly journals Regresión lineal de mínimos cuadrados para la carga y descarga de un condensador

2015 ◽  
Vol 6 (1) ◽  
pp. 34
Author(s):  
José Libardo Santiago-Angarita ◽  
Olga Lucy Rincón-Leal
Keyword(s):  
Linear Regression ◽  
Least Squares ◽  
Current Source ◽  
Mathematical Software ◽  
Method Of Least Squares ◽  
In Series ◽  
Experimental Errors ◽  
Loading And Unloading ◽  
Lineal Regression ◽  
A Current

ResumenEl objetivo es determinar experimentalmente el proceso de carga y descarga de un condensador estando conectado en serie con una resistencia y una fuente de corriente  continua, utilizando para ello los métodos numéricos en el proceso de ajuste de curvas a través de la regresión lineal de mínimos cuadrados, y con ayuda del software matemático Matlab se realizó la construcción de las respectivas curvas. Se estableció una relación entre el voltaje y el tiempo, formándose así una gráfica exponencial; se dedujeron las relaciones existentes y el comportamiento del fenómeno, dadas las ecuaciones y con la ayuda de lasegunda Ley de Kirchhoff; se determinaron las contantes de tiempo utilizando el método de regresión lineal de mínimos cuadrados, encontrándose un error experimental del 5 % con respecto a la constate de tiempo teórica RC.Palabras Claves: Condensador, resistencia y regresión lineal.ABSTRACTThe objective is to determine experimentally S. Process Loading and unloading of un capacitor being connected in series with a resistor and a current source , using para This numerical methods in the process of adjustment curves Through linear regression Least Squares , with the help of mathematical software Matlab building the respective curves was performed.A relationship between the voltage and time, thus forming exponential graph A is established; the relationships and the behavior of the phenomenon were deducted, given the equations and with the help of the Second Law of Kirchhoff; the Time constants were determined using the method of least squares linear regression, experimental errors UN meeting 5% with respect to the I Theoretical RC time constant.Keywords: Condenser, resistance and lineal regression.

Iodometric determination of 2-mercaptobenzthiazole by coulometric titration

1982 ◽  
Vol 47 (2) ◽  
pp. 588-593 ◽  
Author(s):  
Zdeněk Kučera ◽  
Milan Karlík ◽  
Jiří Krofta
Keyword(s):  
Standard Deviation ◽  
Relative Standard Deviation ◽  
Coulometric Titration ◽  
Optimum Conditions ◽  
End Point ◽  
Relative Standard ◽  
Standard Deviations

The optimum conditions were found for the determination of 2-mercaptobenzthiazole (MBT) by coulometric titration with the generated iodine using biamperometric indication of the titration end point. Use is made of the oxidation to the disulphide (n = 1) and to benzothiazole-2-sulphinate (n = 4) in the regions pH 4.5-8.5 and 10-12, respectively. Eight repeated titrations to the disulphide gave the relative standard deviations 0.27% and 1.23% in the determination of 1 675 and 33.5 μg MBT, respectively, seven repeated titrations of 419 μg MBT to benzothiazole-2-sulphinate afforded results with the relative standard deviation 0.34%.

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