Determination of Limits for a Linear Regression or Calibration Curve

1983 ◽  
Vol 15 (3) ◽  
pp. 118-125 ◽  
Author(s):  
William H. Swallow ◽  
J. Richard Trout
Keyword(s):  
Linear Regression ◽  
Calibration Curve

scholarly journals Determination Of Formaldehyde In Tofu From Ciputat Traditional Market With Colorimetry Method

2011 ◽  
Vol 2 (2) ◽  
Author(s):  
Zilhadia Zilhadia ◽  
Sanny Susanti
Keyword(s):  
Linear Regression ◽  
Calibration Curve ◽  
Analytical Method ◽  
Steam Distillation ◽  
Food Product ◽  
Extraction Process ◽  
Sample Extraction ◽  
Traditional Market ◽  
Nash Reagent

Tofu, a food product made from soybean, contain water and it is very easy to overgrown microbes.Based on a survey, many products of tofu contain formaldehyde as preservative. Formaldehyde is apreservative that the use is prohibited for food because it can cause cancer in humans. The aim of thisstudy was determined concentration of formaldehyde in tofu from traditional market Ciputat usingSpectrophotometer UVI-VIS. Steam distillation was used for sample extraction process. Distillate wasreacted with Nash reagent. The equation of calibration curve is y=0,0032x – 0,0079 and correlationcoefficient of the linear regression of 0,9992. The experimental results obtained LOD value of11.1328 μg/ml, LOQ value of 37,1094 μg/mL The precision of this analytical method were lower than2% for each of the sample, while method’s accuration for tofu was 98,69% ± 0,4085%. Results ofsample analysis from Ciputat market, samples were detected containing formaldehyde. Formaldehydeconcentrations are 104,87 μg/mL, 11,21 μg/mL, 1,96 μg/mL, 190,80 μg/mL, 201,98 μg/mL, 10,47μg/mL, and 3,31 μg/mL.

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.

scholarly journals Non-Destructive Micromagnetic Determination of Hardness and Case Hardening Depth Using Linear Regression Analysis and Artificial Neural Networks

Metals ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 18
Author(s):  
Rahel Jedamski ◽  
Jérémy Epp
Keyword(s):  
Neural Network ◽  
Neural Networks ◽  
Regression Analysis ◽  
Artificial Neural Networks ◽  
Linear Regression ◽  
Linear Regression Analysis ◽  
Case Hardening ◽  
Artificial Neural ◽  
Non Destructive

Non-destructive determination of workpiece properties after heat treatment is of great interest in the context of quality control in production but also for prevention of damage in subsequent grinding process. Micromagnetic methods offer good possibilities, but must first be calibrated with reference analyses on known states. This work compares the accuracy and reliability of different calibration methods for non-destructive evaluation of carburizing depth and surface hardness of carburized steel. Linear regression analysis is used in comparison with new methods based on artificial neural networks. The comparison shows a slight advantage of neural network method and potential for further optimization of both approaches. The quality of the results can be influenced, among others, by the number of teaching steps for the neural network, whereas more teaching steps does not always lead to an improvement of accuracy for conditions not included in the initial calibration.

Methodology of Estimation of Fire Separation Distances between Construction Facilities by Calculation

2020 ◽  
Vol 1006 ◽  
pp. 93-100
Author(s):  
Vadym Nizhnyk ◽  
Yurii Feshchuk ◽  
Volodymyr Borovykov
Keyword(s):  
Mathematical Model ◽  
Heat Flux ◽  
Linear Regression ◽  
Ignition Temperature ◽  
Oil Products ◽  
Regression Equations ◽  
Fire Load ◽  
Literary Sources ◽  
Tabular Method

Based on analysis of appropriate literary sources we established that estimation of fire separation distances was based of two criteria: heat flux and temperature. We proposed to use “ignition temperature of materials” as principal criterion when determining fire separation distances between adjacent construction facilities. Based on the results derived while performing complete factorial we created mathematical model to describe trend of changing fire separation distances depending on caloric power of fire load (Q), openings factor of the external enclosing structures (k) and duration of irradiation (t); moreover, its adequacy was confirmed. Based on linear regression equations we substantiated calculation and tabular method for the determination of fire separation distances for a facility being irradiated which contains combustible or otherwise non-combustible façade and a facility where liquid oil products turn. We developed and proposed general methodology for estimation of fire separation distances between construction facilities by calculation.

A Method for Quantitative Phase Analysis of Silicon Nitride by X-Ray Diffraction

1990 ◽  
Vol 5 (3) ◽  
pp. 121-124 ◽  
Author(s):  
David J. Devlin ◽  
Kamal E. Amin
Keyword(s):  
Silicon Nitride ◽  
Iterative Method ◽  
Calibration Curve ◽  
Quantitative Measurement ◽  
Quantitative Phase Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Pure Phases ◽  
Yttrium Disilicate

AbstractThe relative intensities ratios for the determination of the relative amounts of alpha and beta phases in silicon nitride and the relative amounts of delta yttrium disilicate (Y2Si2O7) and nitrogen apatite [Y5(SiO4)3N] are reported. These constants were determined using an iterative method applicable when the pure phases are not easily prepared. In addition, a calibration curve was obtained for the quantitative measurement of free silicon in silicon nitride over the range 0 to 0.3% by weight of Si.

scholarly journals Determination of Sodium Cromoglycate by a New Kinetic Spectrophotometric Method in Biological Samples

2013 ◽  
Vol 2013 ◽  
pp. 1-5
Author(s):  
Mohsen Keyvanfard ◽  
Khadijeh Alizad ◽  
Razieh Shakeri
Keyword(s):  
Standard Deviation ◽  
Sodium Cromoglycate ◽  
Spectrophotometric Method ◽  
Calibration Curve ◽  
Biological Samples ◽  
Limit Of Detection ◽  
Micellar Medium ◽  
Relative Standard ◽  
Kinetic Spectrophotometric

A new kinetic spectrophotometric method is described for the determination of ultratrace amounts of sodium cromoglycate (SCG). The method based on catalytic action of SCG on the oxidation of amaranth with periodate in acidic and micellar medium. The reaction was monitored spectrophotometrically by measuring the decrease in absorbance of the amaranth at 518 nm, for the first 4 min from initiation of the reaction. Calibration curve was linear in the range of 4.0−36.0 ng mL−1SCG. The limit of detection is 2.7 ng mL−1SCG. The relative standard deviation (RSD) for ten replicate analyses of 12, 20, and 28 ng mL−1SCG was 0.40%, 0.32%, and 0.53%, respectively. The proposed method was used for the determination of SCG in biological samples.

scholarly journals Spectrophotometric investigation of the Fe(III)-disulphonate hydroquinone complex

2005 ◽  
Vol 70 (4) ◽  
pp. 651-659
Author(s):  
Mirjana Obradovic ◽  
Snezana Mitic ◽  
Snezana Tosic ◽  
A.N. Pavlovic
Keyword(s):  
Stability Constant ◽  
Spectrophotometric Method ◽  
Calibration Curve ◽  
Relative Stability ◽  
Time Stability ◽  
Acid Media ◽  
Influence Of Temperature ◽  
Complex Dependence ◽  
Indigo Blue

Iron(III) form an indigo-blue complex with the disulphonated product of hydroquinone (K2S2Hy) in acid media with an absorption maxima at 600 nm. The time stability of the complex, dependence of the complex absorbance on pH and the influence of temperature and solvent were followed on the basis of spectrophotometric measurements. Using the Job, mole ratio and Henry?Franck?Ostwald methods, the composition and relative stability constant of this complex, in 80 vol.% ethanol as solvent, were determined (1:1;log??293 = 3.37). A new spectrophotometric method for the determination of iron has been developed and the calibration curve is linear in the concentration range from0.65 to 6.45 ?g cm-3. The effects of foreign ions on the determination of iron were investigated in order to assess the selectivity of the method. The method was applied for the determination of Fe(III) in the natural juice of beet.

scholarly journals Chemometric approach in the development of the colorimetric method for the estimation of food colorants in meat products

2014 ◽  
Vol 68 (6) ◽  
pp. 781-791 ◽  
Author(s):  
Radivoj Petronijevic ◽  
Vesna Matekalo-Sverak ◽  
Aurelija Spiric ◽  
Ilija Vukovic ◽  
Jelena Babic ◽  
...  
Keyword(s):  
Linear Regression ◽  
Mathematical Models ◽  
Multiple Linear Regression ◽  
Linear Models ◽  
Colorimetric Method ◽  
Meat Products ◽  
Food Colorants ◽  
Food Colorant ◽  
Control Batch

The aim of this research was to develop a novel colorimetric method based on mathematical models, by multiple linear regression (MLR), from the CIE L*a*b* measurements and data of the HPLC determination of food colorants. Calibration set of 10 production batches of finely grinded cooked sausage with food colorants added was manufactured in industrial conditions as follows: one control batch and 9 products with various quantities of added food colorants: E120 (3.4, 7.5 and 12.5 mg/kg), E 124 (5.0, 15.0, 25.0 mg/kg) and E 129 (5.0, 15.0, 25.0 mg/kg). The estimation of the added food colorants was assessed by measuring L*, a*, b* parameters of cross-section. The quantification of food colorants was achieved by HPLC-PDA. Food colorants were extracted from meat products using Accelerated Solvent Extraction (ASE). Quantification of food colorants was achieved in the range from 1 to 100 mg / kg, and recovery values were from 76.15% to 107.04%, for E 120, from 97.61% to 101.03%, for E 124 and from 99.91% to 101.67%, for E 129. Correlation of the results obtained using HPLC and colorimetric measuring data was assessed by Multiple Linear Regression (MLR). The results from colorimetric and chromatographic determinations in four experimental batches (three batches with different quantities of food colorants and one control batch) were used for calibration. Coefficients of determination (R2) for linear models in experimental batches were 0.954, for E 124, 0.987, for E 120 and 0.993, for E 129. Correlation functions of food colorant quantities and corresponding L*a*b* values were established. The obtained mathematical models were tested for the estimation of the content of dyes in 21 samples of finely grinded cooked sausages purchased in retail stores. Food colorants were confirmed in 20 samples (95.24 %), and one sample (4.76 %) did not contain any of these compounds. Out of the positive samples, sixteen samples (80.00 %) contained E 120, while four samples (20.00 %) contained E 129. Food colorant E124 was not established in any of the analyzed samples. Colorimetric CIE L*a*b* method might be used during sensory evaluation of meat products for the assessment of the added food colorants.

scholarly journals Validation of Velocity Measuring Devices in Velocity Based Strength Training

2021 ◽  
Vol 20 (1) ◽  
pp. 106-118
Author(s):  
Thorben Menrad ◽  
Jürgen Edelmann-Nusser
Keyword(s):  
Linear Regression ◽  
Strength Training ◽  
Mean Value ◽  
Coefficient Of Determination ◽  
Regression Analyses ◽  
Measuring Devices ◽  
Strength Exercises ◽  
Measurement Units ◽  
Velocity Measuring

Abstract To control and monitor strength training with a barbell various systems are on the consumer market. They provide the user with information regarding velocity, acceleration and trajectory of the barbell. Some systems additionally calculate the 1-repetition-maximum (1RM) of exercises and use it to suggest individual intensities for future training. Three systems were tested: GymAware, PUSH Band 2.0 and Vmaxpro. The GymAware system bases on linear position transducers, PUSH Band 2.0 and Vmaxpro base on inertial measurement units. The aim of this paper was to determine the accuracy of the three systems with regard to the determination of the average velocity of each repetition of three barbell strength exercises (squat, barbell rowing, deadlift). The velocity data of the three systems were compared to a Vicon system using linear regression analyses and Bland-Altman-diagrams. In the linear regression analyses the smallest coefficient of determination (R2.) in each exercise can be observed for PUSH Band 2.0. In the Bland-Altman diagrams the mean value of the differences in the average velocities is near zero for all systems and all exercises. PUSH Band 2.0 has the largest differences between the Limits of Agreement. For GymAware and Vmaxpro these differences are comparable.

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