Comments on “A Simple Gas Chromatograph Sample Introduction System”

Abstract

The utilization of a simple gas chromatograph sample introduction system is expanded from research laboratory to industrial laboratory by using a more readily automated 6-port valve system.     

Comments on “An experimental investigation on heating rate effect in the thermal behavior of perhydrous bituminous coal during pyrolysis”

This paper has the intension of discussing about the published paper by Wu et al. (J Therm Anal Calorim 119:2195–2203, 2015). The original paper has shown some errors in quoting and using the Coats–Redfern integral kinetic equation. This discussion is focused on the employment of this model, and some arguments and clarifications are also given.     

Comments on “Solubility and Dissolution Thermodynamic Data of Cefpiramide in Pure Solvents and Binary Solvents”

Errors are found in the mathematical correlation based on the combined Jouyban–Acree and Modified Apelblat models for describing the variation in the mole fraction solubility of cefpiramide with temperature and solvent composition for the binary aqueous–ethanol solvent system. The equation coefficients given by Tang and coworkers, when substituted into the model equation, do not yield the authors’ calculated mole fraction solubilities of cefpiramide.     

Comments on the article ‘Thermodynamics of Na-based liquid binary alloys’

The discrepancy between results presented in the article ‘Thermodynamics of Na-based liquid binary alloys’ and the nature of such quantities as the heat of mixing and entropy of mixing as well as the discrepancy between results obtained and their interpretation in this paper are discussed. It is concluded that the model pseudopotential used in the work above is not useful for calculating the thermodynamic properties of liquid metal alloys as it is declared by authors of the aforementioned paper.     

Comments on “Molecular Chirality in Classical Spacetime: Solving the Controversy about the Spinning Cone Model of Rotating Molecules”

A recent mathematical analysis by Michel Petijean aimed at solving the Barron/Mislow controversy concerning the chirality or otherwise of a non-translating spinning cone concluded that both are right: the controversy is a matter of an arbitrary choice of a conversion factor. This reassessment highlights the different physicochemical properties of a stationary spinning cone and a chiral molecule and concludes that Petitjean's analysis is misleading.     

Comments on “Crystal growth,spectral, optical,and thermal characterization of glycyl-l-alanine hydrochloride (GLAH) single crystal”

The authors of the title paper (J Therm Anal Calorim 2012,110:873–878) report to have grown a dipeptide hydrochloride crystal namely glycyl-l-alanine hydrochloride by the slow evaporation of an aqueous solution containing stoichiometric amounts of l-alanine and glycine and an excess of hydrochloric acid. In this letter, we prove that no such dipeptide hydrochloride can be crystallized simply by mixing two amino acids in aqueous hydrochloric acid.     

Comments on the article ‘Thermodynamical properties of RbCs liquid binary alloys’

Unphysical results presented in the article ‘Thermodynamical properties of RbCs liquid binary alloys’ are discussed. It is concluded that this paper is pseudo-scientific and misleads readers regarding thermodynamics of binary mixtures.     

Comments to EURACHEM/CITAC guide “Measurement uncertainty arising from sampling”

The EURACHEM/CITAC Guide “Measurement uncertainty arising from sampling” deals with the design and analysis of experiments for the evaluation of the sampling and analytical standard deviation when a defined sampling and analytical method is used for the determination of the concentration, expressed as mass fraction (mg/kg), of an analyte in a specified material. The Guide recommends reporting the relative expanded uncertainty and using it directly, i.e. it implicitly assumes that the standard deviation is proportional to the mass fraction even in case the experimental data do not support this assumption. Example A1 (and some of the other examples of the Guide) demonstrates that this can result in extreme levels of underestimation or overestimation of the uncertainty of measurement results. Hence, such recommendations should be avoided!     

Comments on a CIP rule conundrum: Why I think I’m right

A question is raised as to how the CIP rules as related to a certain class of 2,1-benzothiazines should be applied. There are two subtle rules among the better known ones that seem to work in opposition, thus creating problems for assignments. It appears that one rule has been give precedence over the other at CAS and in programs like Chemdraw. Whether that is appropriate and true to the original rules is called into question.