Search results for "Method"

Methodisches zur bestimmung der molekulargewichtsverteilung von cellulosen

1959

Es wird eine verbesserte Fallungs-Fraktioniermethode zur Ermittlung von Molekulargewichtsverteilungen an Cellulosenitraten beschrieben. Es konnen mit ihr gut reproduzierbare Verteilungskurven erhalten werden, wenn man die notwendigen Bedingungen wie gleichmasige Substitution des Praparates, moglichst kleine Ausgangskonzentration zur Erreichung eines guten Trenneffektes, Vermeidung eines Abbaues wahrend der Fraktionierung usw. in genugender Weise beachtet, – Zur Auswertung der Fraktionierergebnisse raumlich inhomogener Praparate (wie z. B. merzerisierte und oxydativ abgebaute Baumwollen) wird ein statistisches Verfahren vorgeschlagen. An improved method of preciptation fractionation for dete…

Alcoholic nanolime dispersion obtained by the insolubilisation-precipitation method and its application for the deacidification of ancient paper

2017

Abstract Nanolime dispersions for the deacidification of ancient paper constitute a valid alternative to the lime traditional ones. Their efficacy depends on particles size, polydispersity and agglomeration that can be controlled depending on the preparation method. In this work, nanolime preparation by insolubilisation-precipitation method is reported. Nanoparticles dispersed in a water-isopropanol mixture were obtained without any manipulation of the dispersion. The stability of the dispersion together with particle size and morphology were found to be dependent on water to isopropanol molar ratio and on the synthesis temperature. One of the dispersion was applied on a manuscript to asses…

SilicaROD™ — A new challenge in fast high-performance liquid chromatography separations

1998

Abstract High performance liquid chromatography (HPLC) has become one of the most used methods for the analysis of compound mixtures in industry, especially for the quality control of products. Nowadays productivity is the major and dominant upcoming issue, i.e. the goal is to drastically reduce the analysis time and cost per analysis. The solution of the task is higher throughput and faster HPLC methods. Here we describe a new monolithic type of HPLC column, the SilicaROD™ column, which permits the fast HPLC separation of compound mixtures within a few minutes.

Sunscreen analysis

2005

Although there are no official analytical methods for UV filters determination in sunscreen cosmetics, their maximum content are regulated by legislation, and then analytical methods to control these products are necessary. In this paper, analytical methods for UV filters determination in cosmetics, which can be found in the literature, are reviewed. The usefulness of the analytical methods, techniques and sample preparation is discussed. The analytical methods used for the determination of UV filters in other type of samples are commented upon. Moreover, a brief overview of the European Union legislation concerning UV filters is included.

A study on the essential oil of Ferulago campestris : How much does extraction method influence the oil composition?

2011

The essential oil of different parts of Ferulago campestris (Bess.) collected in Sicily has been extracted by microwave-assisted hydrodistillation (MAHD) and by classic hydrodistillation (HD). A comparative qualitative-quantitative study on the composition of the oils was carried out. A total of 100 compounds were identified in the oils obtained by MAHD, whereas 88 compounds characterized the HD oils. The most prominent components were, in all different parts of F. campestris and in both extraction methods, 2,4,5-trimethylbenzaldehyde and 2,4,6-trimethylbenzaldehyde isomers; the latter was not previously found. The attempt to evaluate where the oil components are located in all parts of the…

Estimation of diuretic drugs in biological fluids by HPLC

1992

This critical review of different methods proposed for the determination and screening of diuretics is directed mainly, because of its potential application, towards highperformance liquid chromatography.

Application of a new glass capillary chromatographic technique in the analysis of phenoxyacetic acid herbicides.

1976

Combined effect of solvent content, temperature and pH on the chromatographic behaviour of ionisable compounds. III: Considerations about robustness

2009

Abstract We previously reported a model able to predict the retention time of ionisable compounds as a function of the solvent content, temperature and pH [J. Chromatogr. A 1163 (2007) 49]. The model was applied further, developing an optimisation of the resolution based on the peak purity concept [J. Chromatogr. A 1193 (2008) 117]. However, we left aside an important issue: we did not consider incidental overlaps caused by shifts in the predicted peak positions, owing either to uncertainties in the source data, modelling errors, or the practical implementation in the chromatograph of the optimal mobile phase (or any other). These shifts can ruin the predicted separation, since they can eas…

Are deep eutectic solvents useful in chromatography? A short review.

2021

A literature update has been done concerning Deep Eutectic Solvents (DES) use in chromatography applications. The literature survey was based on the period from 2010 till 2020 and manuscripts reported in the data bases Web of Science and Scopus. The use of DES as mobile phase and mobile phase additives, stationary phases and solid phase modifiers and the use of DES as reaction solvents for chromatography use, were evaluated. Emphasis was placed on the differentiation of DES and Ionic Liquids (ILs) and the advanced green characteristics of the new solvents as compared with traditional organic solvents and ILs with a look into the drawbacks and future perspectives in the field of separation m…

Comparison of two vibrational procedures for the direct determination of mancozeb in agrochemicals.

2007

The direct determination of mancozeb in agrochemicals has been made by diamond attenuated total reflectance (ATR) Fourier transform infrared spectroscopy in the middle range (DATR-MIR) and diffuse reflectance infrared Fourier transform spectroscopy in the near range (DR-NIR) methods using in both cases a previous identification of the samples using a dendrographic classification and an appropriate partial least squares (PLS) calibration established from a set of nine external standards and optimized for each type of sample. It was analyzed a heterogeneous population of 11 samples obtained from the Spanish market, containing different co-formulated products, such as fosetyl-Al, copper oxychl…