Calibration curve equation in local voltammetry of heterogeneous alloys

2017 ◽  
Vol 72 (2) ◽  
pp. 203-205
Author(s):  
E. Yu. Moshchenskaya ◽  
V. V. Slepushkin ◽  
Yu. V. Rublinetskaya ◽  
B. I. Kashkarov
Keyword(s):  
Calibration Curve ◽  
Curve Equation ◽  
Heterogeneous Alloys ◽  
Local Voltammetry

Calibration curve equation in the local voltammetry of eutectic alloys with anomalous and divorced eutectics

2017 ◽  
Vol 72 (1) ◽  
pp. 105-106
Author(s):  
B. I. Kashkarov ◽  
Yu. V. Rublinetskaya ◽  
E. Yu. Moshchenskaya ◽  
V. V. Slepushkin
Keyword(s):  
Calibration Curve ◽  
Eutectic Alloys ◽  
Curve Equation ◽  
Local Voltammetry

Developing New Criteria for Validity Evaluation of Analytical Methods

2019 ◽  
Vol 102 (6) ◽  
pp. 1908-1916 ◽  
Author(s):  
Ali Shayanfar ◽  
Saba Ershadi
Keyword(s):  
Calibration Curve ◽  
Analytical Methods ◽  
Inorganic Compounds ◽  
Linear Range ◽  
Coefficient Of Determination ◽  
Inaccurate Data ◽  
Scientific Papers ◽  
Curve Equation ◽  
New Criteria ◽  
Validity Evaluation

Abstract Background: The appropriate validation of analytical methods has become an essential part of the determination of chemical substances. Invalid analytical methods lead to inaccurate data and misinterpretation of results in the pharmaceutical, food, and medical sciences. There are a number of guidelines issued on validation by international organizations. Some parameters have been proposed to evaluate the validity of an analytical method. They are accurate and comprehensive; however, proposing new criteria can help analysts to detect invalid methods. Objective: In this study, new criteria are proposed based on upper and lower limits of linear range and calculated responses by calibration curve equation. Methods: Further research on 150 reported analytical methods (non–separation-based and separation-based techniques) for chemicals and pharmaceuticals (organic and inorganic compounds) in scientific papers revealed that employing the coefficient of determination (R2) alone could lead analysts to an inaccurate linear range and method validation, and consequently, results showed that only 55% of these methods count as valid approaches. Conclusions: The established criteria based on the calibration curve equation and linear range appear to be applicable and suitable for validity evaluation of analytical methods.

scholarly journals ANALISIS KANDUNGAN KAFEIN PADA KOPI DI DESA SESAOT NARMADA MENGGUNAKAN SPEKTROFOTOMETRI UV-VIS

Jurnal Kimia ◽  
2016 ◽  
Author(s):  
Aryanu Fahmi Arwangga ◽  
Ida Ayu Raka Astiti Asih ◽  
I Wayan Sudiarta
Keyword(s):  
Water Content ◽  
Correlation Coefficient ◽  
Calibration Curve ◽  
Coffee Bean ◽  
Caffeine Content ◽  
Coffee Powder ◽  
Food And Drink ◽  
Curve Equation ◽  
Maximum Limit ◽  
Standard Solutions

Coffee is one of the agriculture commodities that are cultivated by farmers. One of the compounds in the coffee is caffeine. Caffeine is one of alkaloids which contains in coffee bean. The purpose of this study was to determine the contents of caffeine in unripe coffee, pure coffee powder, and mix coffee powder by using UV-Vis spectrophotometer. Standard solutions of caffeine used were 1 ppm; 3 ppm; 6 ppm; 9 ppm; 12 ppm; and 15 ppm. Caffeine calibration curve equation was y = 0.0494x ??+ 0.01862 with a correlation coefficient (r) of 0.99714. Caffeine content in unripe coffee was 1,28±0,82 % with water content 3%, pure coffee powder 1,63±0,13 % with water content 1%, and mix coffee powder 0,87±0,01 % with water content 1%. According to SNI 01-7152-2006 maximum limit of caffeine in food and drink was 150 mg/day and 50 mg/dish.

scholarly journals ACTIVITY AND ACTIVITY COEFFICIENTS OF DISSOLVING PHASE OF HETEROGENEOUS ALLOY UNDER CONDITIONS OF LOCAL VOLTAMPEROMETRY

2018 ◽  
Vol 59 (2) ◽  
pp. 22
Author(s):  
Vyacheslav V. Slepushkin ◽  
Yuliya V. Rublinetskaya ◽  
Elena Yu Moshchenskaya ◽  
Boris I. Kashkarov
Keyword(s):  
Activity Coefficients ◽  
Dissolution Process ◽  
Calibration Curves ◽  
Heterogeneous Alloy ◽  
Anode Dissolution ◽  
Heterogeneous Alloys ◽  
Local Voltammetry

The new expressions for the activity coefficients of dissolving phase and for calibration curves i=f(С) are presented as the result of development of previous studies of an anode dissolution process of heterogeneous alloys at the conditions of local voltammetry.

Developing New Criteria for Validity Evaluation of Analytical Methods

2019 ◽  
Vol 102 (6) ◽  
pp. 1908-1916 ◽  
Author(s):  
Ali Shayanfar ◽  
Saba Ershadi
Keyword(s):  
Calibration Curve ◽  
Analytical Methods ◽  
Inorganic Compounds ◽  
Linear Range ◽  
Coefficient Of Determination ◽  
Inaccurate Data ◽  
Scientific Papers ◽  
Curve Equation ◽  
New Criteria ◽  
Validity Evaluation

Background: The appropriate validation of analytical methods has become an essential part of the determination of chemical substances. Invalid analytical methods lead to inaccurate data and misinterpretation of results in the pharmaceutical, food, and medical sciences. There are a number of guidelines issued on validation by international organizations. Some parameters have been proposed to evaluate the validity of an analytical method. They are accurate and comprehensive; however, proposing new criteria can help analysts to detect invalid methods. Objective: In this study, new criteria are proposed based on upper and lower limits of linear range and calculated responses by calibration curve equation. Methods: Further research on 150 reported analytical methods (non–separation-based and separation-based techniques) for chemicals and pharmaceuticals (organic and inorganic compounds) in scientific papers revealed that employing the coefficient of determination (R2) alone could lead analysts to an inaccurate linear range and method validation, and consequently, results showed that only 55% of these methods count as valid approaches. Conclusions: The established criteria based on the calibration curve equation and linear range appear to be applicable and suitable for validity evaluation of analytical methods.

scholarly journals A Simple Kinetic Spectrophotometric Method For The Determination of Certain 4-Quinolones in Drug Formulations.

2000 ◽  
Vol 68 (2) ◽  
pp. 173-188 ◽  
Author(s):  
M. Rizk ◽  
F. Belal ◽  
F. Ibrahim ◽  
S. M. Ahmed ◽  
N. M. El-Enany
Keyword(s):  
Spectrophotometric Method ◽  
Calibration Curve ◽  
Room Temperature ◽  
Fixed Time ◽  
Acidic Media ◽  
Calibration Equation ◽  
Fixed Concentration ◽  
Kinetic Spectrophotometric ◽  
Curve Equation

An accurate simple and selective kinetic procedure for the determination of certain 4-quinolones namely, norfloxacin (I), ofloxacin (II), enrofloxacin (III), fleroxacin (IV), ciprofloxacin (V) and pefloxacin (VI) is described. The procedure is based on reacting the studied compounds in acidic media (0.1 M HCL) with 3-methyl-2-benzothiazolinone hydrazone hydrochloride (MBTH) in presence of cerium (IV) ammonium sulphate as an oxidant at room temperature for a fixed time of 20 min. for (I), (III), 12 min for (II) and 30 min for IV , V and VI, then the absorbance of the reaction product is measured at 630 nm. The concentration of the studied compounds is computed using the corresponding calibration curve equation for the fixed-time method. The absorbance-concentrations plot is rectilinear over the range 20-100 ug.ml-1 for (I), 2 - 20 ug.ml-1 for (II), 10 - 74 ug.ml-1 for (III), 10 - 60 ug.ml-1 for IV, 10 - 50 ug.ml-1 for IV and 8 - 40 ug.ml-1 for VI. The determination of the studied compounds by the fixed-concentration and rate constant methods is feasible with the calibration equation obtained, but the fixed-time method proved to be more applicable. The procedure was applied successfully to commercial tablets and ampoules and the results obtained were compared statistically with the reference methods.

COMPARISON OF VARIOUS METHODS FOR THE CHEMICAL ASSAY OF CORTICOIDS IN URINE

1955 ◽  
Vol 18 (4) ◽  
pp. 374-378
Author(s):  
Mogens Sprechler
Keyword(s):  
Calibration Curve ◽  
Periodic Acid ◽  
Reducing Power ◽  
Standard Technique ◽  
Phosphomolybdic Acid ◽  
Florisil Column ◽  
Chemical Assay ◽  
Chromatographic Procedure ◽  
Acid Reagent

SUMMARY Since 1949 about 10,000 urinary corticoid analyses have been performed routinely in our laboratory. The method used for this purpose was described in 1950 (Sprechler). We determine the corticoids which can be extracted from the urine with chloroform immediately after acidification to pH 1. The extract is washed with sodium hydroxide and water, a Girard separation is performed, and finally the reducing power of the ketonic fraction is measured by means of the phosphomolybdic acid reagent reaction. During the last few years two other chemical reactions have been used for comparison: The formaldehyde and the Porter-Silber method. After a thorough examination of the above methods a standard technique was followed. In the formaldehyde method a microdiffusion in a Conway unit was used instead of distillation of the formaldehyde following the oxidation with periodic acid. The calibration curve was corrected for loss of material by taking the standard doses of DOC through all the procedures of the method. A micromodification of the Porter-Silber method was chosen. Furthermore attempts were made to determine how specific the chromatographic procedure is in the determination of steroids in urinary extracts. For this purpose the Florisil column was used, and the technique described by Nelson & Samuels was followed. Finally we have investigated the glucuronide-bound corticoids in urine in a smaller series of objects.

Considering the impact of intermittent discharges when modelling overflows

1998 ◽  
Vol 38 (10) ◽  
pp. 23-30
Author(s):  
Sarah Jubb ◽  
Philip Hulme ◽  
Ian Guymer ◽  
John Martin
Keyword(s):  
Water Quality ◽  
Dissolved Oxygen ◽  
Preliminary Investigation ◽  
Oxygen Demand ◽  
Sediment Oxygen Demand ◽  
Combined Sewer Overflows ◽  
River Hydraulics ◽  
Combined Sewer ◽  
The Impact ◽  
Curve Equation

This paper describes a preliminary investigation that identified factors important in the prediction of river water quality, especially regarding dissolved oxygen (DO) concentration. Intermittent discharges from combined sewer overflows (CSOs) within the sewerage, and overflows at water reclamation works (WRW) cause dynamic conditions with respect to both river hydraulics and water quality. The impact of such discharges has been investigated under both wet and dry weather flow conditions. Data collected from the River Maun, UK, has shown that an immediate, transient oxygen demand exists downstream of an outfall during storm conditions. The presence of a delayed oxygen demand has also been identified. With regard to modelling, initial investigations used a simplified channel and the Streeter-Phelps (1925) dissolved oxygen sag curve equation. Later, a model taking into account hydrodynamic, transport and dispersion processes was used. This suggested that processes other than water phase degradation of organic matter significantly affect the dissolved oxygen concentration downstream of the location of an intermittent discharge. It is proposed that the dynamic rate of reaeration and the sediment oxygen demand should be the focus of further investigation.

scholarly journals Calibration of Radiocarbon Dates for the Late Pleistocene Using U/Th Dates on Stalagmites

Radiocarbon ◽  
1997 ◽  
Vol 39 (1) ◽  
pp. 27-32 ◽  
Author(s):  
John C. Vogel ◽  
Joel Kronfeld
Keyword(s):  
South Africa ◽  
Magnetic Dipole ◽  
Satisfactory Agreement ◽  
Late Pleistocene ◽  
Calibration Curve ◽  
Dipole Field ◽  
Radiocarbon Dates ◽  
The Past ◽  
The Earth ◽  
Magnetic Dipole Field

Twenty paired 14C and U/Th dates covering most of the past 50,000 yr have been obtained on a stalagmite from the Cango Caves in South Africa as well as some additional age-pairs on two stalagmites from Tasmania that partially fill a gap between 7 ka and 17 ka ago. After allowance is made for the initial apparent 14C ages, the age-pairs between 7 ka and 20 ka show satisfactory agreement with the coral data of Bard et al. (1990, 1993). The results for the Cango stalagmite between 25 ka and 50 ka show the 14C dates to be substantially younger than the U/Th dates except at 49 ka and 29 ka, where near correspondence occurs. The discrepancies may be explained by variations in 14C production caused by changes in the magnetic dipole field of the Earth. A tentative calibration curve for this period is offered.

Sign in / Sign up

Export Citation Format

Share Document