Construction of Analytical Curve Fit Models for Simvastatin using Ordinary and Weighted Least Squares Methods

Marques-Marinho, Flávia Dias; Reis, Ilka Afonso; Vianna-Soares, Cristina Duarte; Products, Pharmaceutical

doi:10.5935/0103-5053.20130187

Cited by 2 publications

(2 citation statements)

References 1 publication

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“…This result indicated that the concentrations calculated by students in their analyses by HPLC need to be evaluated carefully because when OLS is applied with heteroscedastic data, the true variance of the estimates can be biased, which may lead to obtain incorrect results [1,15]. It has been demonstrated that despite the proportional error for heteroscedastic data is maintained most of the range of practical interest, it becomes constant in the low-signal limit [11,12].…”

Section: Homoscedasticity/heteroscedasticity Evaluationmentioning

confidence: 99%

Ordinary Least Squares with Laboratory Calibrations: A Practical Way to Show Students that This Fitting Model may Easily Yield Biased Results When Used Indiscriminately

Sánchez¹

2017

WJAC

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Analytical calibration using ordinary least squares (OLS) is the most widely applied response function for calibration in all type of laboratories. However, this calibration function is not always the most adequate and its indiscriminant use can lead to obtain biased estimates of unknowns. Students need to be taught about the practical requirements needed to obtain good results with OLS and when this fitting method is not accurate. Different experimental calibration curves were obtained in laboratory sessions using two common instrumental techniques: chromatography and atomic absorption spectrometry. After discussion seminars evaluating the data obtained by students, they were able to understand that linear fitting was not the most accurate model using atomic absorption spectrometry and a quadratic fitting provided most accurate estimates. Linearity was confirmed in chromatographic calibrations, but data presented heteroscedasticity, which is very common in calibrations done in chemical and biological analyses. A simple experiment was applied to show students how the use of the regression coefficients obtained by OLS with heteroscedastic data lead to highly biased estimates near the quantification limits of the calibration curve. The results obtained allowed to show students that, despite being widely used, OLS is not the most adequate fitting model to obtain accurate and precise results with many calibration methods routinely used in chemical and biological laboratories.

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Section: Homoscedasticity/heteroscedasticity Evaluationmentioning

confidence: 99%

Ordinary Least Squares with Laboratory Calibrations: A Practical Way to Show Students that This Fitting Model may Easily Yield Biased Results When Used Indiscriminately

Sánchez¹

2017

WJAC

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“…A comparison was made of the pharmacokinetics in rats of eriodictyol administered as a dissolved solution in saline/PEG400/Tween80 (75/20/5, v/v/v) versus administration as an undissolved suspension in 1% sodium carboxymethylcellulose (NaCMC). The latter material is a common suspending and dissolution agent for solid powders in pharmaceutical drug delivery and the food industry. , Time courses for the appearances of eight metabolites in whole blood extracts are reported. Differences in dose amounts (25 mg kg –1 versus 100 mg kg –1 ) on the pharmacokinetics of eriodictyol were also investigated.…”

Section: Introductionmentioning

confidence: 99%

Influences of Solubility and Vehicle Carriers on Eriodictyol Pharmacokinetics in Rats

Manthey

Ferreira

César

2022

J. Agric. Food Chem.

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In this study, the pharmacokinetics of oral doses of eriodictyol in 1% sodium carboxymethylcellulose and in saline/ PEG400/Tween80 (75/20/5, v/v/v) in rats were compared. The pharmacokinetics of eriocitrin administered as a dissolved solution in water were also characterized. Metabolites of eriodictyol and eriocitrin in whole blood consisted mainly of eriodictyol, homoeriodictyol, and hesperetin glucuronides and ring-fission metabolites. In whole blood, no free nonconjugated flavanone aglycones were detected. Significant differences were observed in the pharmacokinetics of eriodictyol administered as a suspension in 1% sodium carboxymethylcellulose versus administration as a dissolved solution in saline/PEG400/Tween80 (75/20/5, v/v/v). At a dose of 25 mg kg −1 eriodictyol administered with 1% sodium carboxymethylcellulose, a biphasic pharmacokinetic curve was observed, while only a single concentration peak was observed following an administration of 25 mg kg −1 eriodictyol dissolved in saline/PEG400/Tween80 (75/20/5, v/v/v). For all trials, the pharmacokinetics of eriodictyol differed from those of eriocitrin dissolved in water.

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Construction of Analytical Curve Fit Models for Simvastatin using Ordinary and Weighted Least Squares Methods

Cited by 2 publications

References 1 publication

Ordinary Least Squares with Laboratory Calibrations: A Practical Way to Show Students that This Fitting Model may Easily Yield Biased Results When Used Indiscriminately

Ordinary Least Squares with Laboratory Calibrations: A Practical Way to Show Students that This Fitting Model may Easily Yield Biased Results When Used Indiscriminately

Influences of Solubility and Vehicle Carriers on Eriodictyol Pharmacokinetics in Rats

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