Analytical Chemistry Insights

The acid dissociation constant (pK a ) is among the most frequently used physicochemical parameters, and its determination is of interest to a wide range of research fields. We present a brief introduction on the conceptual development of pK a as a physical parameter and its relationship to the concept of the pH of a solution. This is followed by a general summary of the historical develop- ment and current state of the techniques of pKa determination and an attempt to develop insight into future developments. Fourteen methods of determining the acid dissociation constant are placed in context and are critically evaluated to make a fair comparison and to determine their applications in modern chemistry. Additionally, we have studied these techniques in light of present trends in science and technology and attempt to determine how these trends might affect future developments in the field.

JC Jetse Reijenga

van Ajf Arno Hoof

van Ahm Antonie Loon

Ajp Bram Teunissen

Development of Methods for the Determination of pK a Values

pKa值测定方法的发展

A stability-indicating reversed-phase high performance liquid chromatography (RP-HPLC) method was developed for the determination of betaxolol hydrochloride, a drug used in the treatment of hypertension and glaucoma. The desired chromatographic separation was achieved on a Nucleosil C18, 4 μm (150 × 4.6 mm) column, using isocratic elution at a 220 nm detector wavelength. The optimized mobile phase consisted of a 0.02 M potassium dihydrogen phosphate: methanol (40:60, v/v, pH 3.0 adjusted with o-phosphoric acid) as solvent. The flow rate was 1.6 mL/min and the retention time of betaxolol hydrochloride was 1.72 min. The linearity for betaxolol hydrochloride was in the range of 25 to 200 μg/mL. Recovery for betaxolol hydrochloride was calculated as 100.01%-101.35%. The stability-indicating capability was established by forced degradation experiments and the separation of unknown degradation products. The developed RP-HPLC method was validated according to the International Conference on Harmonization (ICH) guidelines. This validated method was applied for the estimation of betaxolol hydrochloride in commercially available tablets.

Sylvain Auvity

Fouad Chiadmi

Salvatore Cisternino

Jean-Eudes Fontan

Joël Schlatter

A Rapid Stability-Indicating RP-HPLC Method for the Determination of Betaxolol Hydrochloride in Pharmaceutical Tablets

一种用于测定盐酸倍他洛尔片剂的快速稳定性指示RP-HPLC方法

Diets rich in omega-3 fatty acids (n-3 FA) have been associated with several health benefits. With the increased interest in n-3 FA both scientifically and societally, the accurate detection of such analytes has become increasingly important. Recently, tandem mass spectrometry (MS/MS) with electrospray ionization interface (ESI), hyphenated to both gas chromatography (GC) and liquid chromatography (LC), has become a valuable tool in the detection of docosahexaenoic acid (DHA). Liquid chromatography-electrospray ionization interface-tandem mass spectrometry methods have been developed for the determination of DHA in canine and poultry species. The objective of this article is to investigate whether LC-ESI-MS/MS is fit for purpose for the determination of DHA in laying hen serum. The disclosure of this work will be beneficial for researchers investigating poultry enrichment for regulatory and toxicological studies. The method was found to be linear over the range. Precision and accuracy results met acceptance criteria and the Limit of Quantitation (LOQ) was established as 1 µg/mL. Recoveries of DHA were obtained for quality control samples and stability studies were performed. The results of the verification study complimented those of the validation study. In summation, the method was established as fit for purpose for measuring total DHA in laying hen serum.

Gerald Patrick Dillon

Geoff Wallace

Alexandros Yiannikouris

Colm Anthony Moran

An Accurate Assessment of Docosahexaenoic Acid in Laying Hen Serum for Regulatory Studies

用于监管研究的产蛋鸡血清中二十二碳六烯酸的准确评估

The aim of this study was to perform green synthesis of silver nanoparticles (AgNPs) from the leaf extract of Desmostachya bipinnata (Dharba), a medicinally important herb which is widely used across India. Synthesized AgNPs were analyzed by UV-Visible spectroscopy, X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDAX). The results have confirmed that green synthesis of AgNPs leads to the fabrication of sphere-shaped particles with a diameter of 53 nm. Furthermore, these AgNPs were subjected to antioxidant and antimicrobial studies against gram-negative and gram-positive bacteria, where AgNPs at a concentration of 20 mg/mL showed highest zone of inhibition. Synthesized AgNPs were evaluated for their antioxidant activity by 1, 1-diphenyl-2-picryl hydrazyl radical (DPPH), H2O2, and superoxide inhibiting assays; increasing concentration has showed increase in scavenging ability. Cell toxicity was assessed on HepG2 cell lines, and synthesized nanoparticles at a concentration of 128 μg/mL produced significant reduction in viability of Hep cells (P < .05). The availability of Dharba throughout the year and the eco-friendly approach in the synthesis of AgNPs coupled with bioactivity has demonstrated its potential as a novel biomaterial which can be used for various biomedical applications.

Sitaramanjaneya Reddy Guntur

NS Sampath Kumar

Manasa M Hegde

Vijaya R Dirisala

In Vitro Studies of the Antimicrobial and Free-Radical Scavenging Potentials of Silver Nanoparticles Biosynthesized From the Extract of <i>Desmostachya bipinnata</i>

体外研究银纳米颗粒的抗菌和自由基清除潜力：从<i>Desmostachya bipinnata</i>提取物生物合成

Fast Green (FCF) dye is commonly used in both cytology and histology applications. Previous studies have found that it can cause mutagenic and tumorigenic effects in experimental human and animal populations. It can also be a source of skin, eye, respiratory, and digestive irritation. The purpose of this study was to examine the use of thin film membranes to degrade FCF. A thin film membrane of chitosan (CS) was fabricated and subsequently filled with zinc oxide nanoparticles (ZnO) or ZnO/CuO-heterostructured nanocomposites. The CS membrane was used as a matrix, and the nanomaterials were used as photocatalysts. The prepared membranes were characterised by four analytical techniques: atomic force microscopy, scanning electron microscopy, X-ray diffraction, and energy-dispersive X-ray analyses. The photocatalytic activity of the fabricated membranes was evaluated by performing experiments in which aqueous solutions of FCF dye that contained the fabricated membrane were irradiated with solar light or UV light. The photodegradation percentage was spectrophotometrically determined by monitoring the maximum wavelengths (λ max ) of FCF at 623 nm for different irradiation times. The decolourisation percentages of the dye under solar light were 57.90% and 60.23% using the CS-ZnO and CS-ZnO/CuO membranes, respectively. When UV light irradiation was employed as the source of irradiation, the photodegradation percentages of FCF were 71.45% and 91.21% using the CS-ZnO and CS-ZnO/CuO membranes, respectively. These results indicated that the best photocatalytic system for the degradation of FCF dye was CS-ZnO/CuO membrane in combination with UV light irradiation. The study also found that it was easy to separate the prepared membranes after the reaction without the need for a centrifuge or magnet. The results demonstrate the potential for CS-ZnO and CS-ZnO/CuO membranes for use as effective sorbents during the process of photodegradation of harmful dyes within waste water recycling practices.

Eman Alzahrani

Chitosan Membrane Embedded With ZnO/CuO Nanocomposites for the Photodegradation of Fast Green Dye Under Artificial and Solar Irradiation

壳聚糖膜嵌入ZnO/CuO纳米复合材料用于人工和太阳光照射下快速绿染料的光降解

The quality of research antibodies is an issue for decades. Although several papers have been published to improve the situation, their impact seems to be limited. This publication makes the effort to simplify the description of validation criteria in a way that the occasional antibody user is able to assess the validation level of an immunochemical reagent. A simple, 1-page checklist is supplied for the practical application of these criteria.

Michael G Weller

Ten Basic Rules of Antibody Validation

抗体验证的十大基本规则

Mineral oils (such as paraffinum liquidum or white oil), which consist of mineral oil saturated hydrocarbons (MOSH) and mineral oil aromatic hydrocarbons (MOAH), are widely applied in various consumer products such as medicines and cosmetics. Contamination of food with mineral oil may occur by migration of mineral oil containing products from packaging materials, or during the food production process, as well as by environmental contamination during agricultural production. Considerable analytical interest was initiated by the potential adverse health effects, especially carcinogenic effects of some aromatic hydrocarbons. This article reviews the history of mineral oil analysis, starting with gravimetric and photometric methods, followed by on-line-coupled liquid chromatography with gas chromatography and flame ionization detection (LC-GC-FID), which still is considered as gold standard for MOSH-MOAH analysis. Comprehensive tables of applications in the fields of cosmetics, foods, food contact materials, and living organisms are provided. Further methods including GCxGC-MS methods are reviewed, which may be suitable for confirmation of LC-GC-FID results and identification of compound classes. As alternative to chromatography, nuclear magnetic resonance (NMR) spectroscopy has recently been suggested for MOSH-MOAH analysis, especially with the possibility of detecting only the toxicologically relevant aromatic rings. Furthermore, NMR may offer potential as rapid screening especially with low-field instruments usable for raw material control.

Sandra Weber

Karola Schrag

Gerd Mildau

Thomas Kuballa

Stephan G Walch

Dirk W Lachenmeier

Analytical Methods for the Determination of Mineral Oil Saturated Hydrocarbons (MOSH) and Mineral Oil Aromatic Hydrocarbons (MOAH)—A Short Review

矿物油饱和烃（MOSH）和矿物油芳香烃（MOAH）测定分析方法——简要综述

出版信息	出版商: Libertas Academica Ltd.，出版周期: ，期刊类型: journal，开源期刊: 否
基本数据	创刊年份: 2008，原创研究文献占比: ，自引率:， Gold OA占比:

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Development of Methods for the Determination of pK a Values

Development of Methods for the Determination of pK a Values

Development of Methods for the Determination of pK a Values

Development of Methods for the Determination of pK a Values

A Rapid Stability-Indicating RP-HPLC Method for the Determination of Betaxolol Hydrochloride in Pharmaceutical Tablets

An Accurate Assessment of Docosahexaenoic Acid in Laying Hen Serum for Regulatory Studies

In Vitro Studies of the Antimicrobial and Free-Radical Scavenging Potentials of Silver Nanoparticles Biosynthesized From the Extract of Desmostachya bipinnata

Chitosan Membrane Embedded With ZnO/CuO Nanocomposites for the Photodegradation of Fast Green Dye Under Artificial and Solar Irradiation

Ten Basic Rules of Antibody Validation

Analytical Methods for the Determination of Mineral Oil Saturated Hydrocarbons (MOSH) and Mineral Oil Aromatic Hydrocarbons (MOAH)—A Short Review