There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Statistics for analytical chemistry

From 1993 to 1995, with a conventional fluorescence spectrophotometer (CFS) (convenient) and working in a synchronous scan model (easy-to-use), Pasternack et al. proposed the resonance light-scattering (RLS) technique, to efficiently characterize self-assemblies or self-aggregations of chromophores with good electronic coupling. Incident wavelengths were specially considered within their absorption envelopes (rather unorthodox), and their amplified signals were observed (good sensitivity and selectivity). Due to these absorbing benefits, RLS technique, as a novel readout method, commenced on its exciting analytical tours soon after Liu et al. and especially Li et al., separately, set out their corresponding pioneering investigations from 1995 to 1997. From then on, it has received an increasing attention by analysts, as a consequence exhibiting more and more fascinating analytical applications. Moreover, various attractive RLS-derived techniques have been developed successively to improve it or to enlarge its possibilities. Later on, Liu et al. and Li et al., Tabak et al., Yguerabide et al., Huang et al., Lakowicz et al. and Fernandez Band et al. have made their outstanding contributions. In this review, we concentrate on major achievements of RLS in analytical chemistry for over a decade, involving the developments and analytical applications of RLS derived techniques treated as an impacting progress of RLS technique in analytical chemistry. Finally, an indication of future directions of RLS technique in analytical chemistry is provided.

Resonance light scattering and derived techniques in analytical chemistry: past, present, and future

Electroanalysis is a powerful analytical technique that is increasing in utility in the pharmaceutical industry. It is used as an alternative or complementary technique to spectrophotometric and separation techniques due to its high sensitivity, speed of analysis, reduction in solvent and sample consumption, and low operating cost compared to other analytical methods. A review of the principles and application of modern electroanalytical techniques, namely, cyclic, linear sweep, differential pulse, square wave and stripping voltammetric techniques, is presented. This review gives recent pharmaceutical analysis applications used for each mode of electroanalytical chemistry. The review will also describe recent developments for enhancing concentration limits of detection, electrode types, and so forth. Selected studies on these subjects are given as examples.

Electroanalytical Methods for the Determination of Pharmaceuticals: A Review of Recent Trends and Developments

Lasers and laser spectroscopic techniques have been extensively used in several applications since their advent, and the subject has been reviewed extensively in the last several decades. This review is focused on three areas of laser spectroscopic applications in atmospheric and environmental sensing; namely laser-induced fluorescence (LIF), cavity ring-down spectroscopy (CRDS), and photoluminescence (PL) techniques used in the detection of solids, liquids, aerosols, trace gases, and volatile organic compounds (VOCs).

Laser Spectroscopy for Atmospheric and Environmental Sensing

Phenothiazine derivatives substituted in the 2 and 10 positions belong to a big group of tricyclic aromatic compounds. They are in extensive use in psychiatry as tranquilizers and neuroleptics. Due to their characteristic structure they exhibit many valuable analytical properties. They are easily oxidized in an acidic medium while generating color products. They also react with some thiocyanate and halide complexes of metals as well as some organic compounds, and form well-defined ion-association complexes. The properties mentioned above are the basis for utilizing the phenothiazine derivatives as reagents for chemical analysis. The physical and chemical properties of 2, 10-disubstituted phenothiazine derivatives are described in the presented paper in detail. The paper is divided into seven parts. The first chapter presents the physical properties of the phenothiazine derivatives, such as their physical state, thermal stability and solubility. The next part of the paper is devoted to the spectral properties of 2, 10-disubstituted phenothiazine derivatives. The influence of the type of substituents on the intensity and shape of the UV and fluorescence spectra of phenothiazine derivatives are discussed. Chapters 4 and 5 show the run and the mechanism of phenothiazine derivatives oxidation, their electrochemical properties and the analytical aspects of the described processes. Chapter 6 of the present paper is devoted to the complexing abilities of the phenothiazine derivatives. The paper is based on a review of the chemical literature up to 1995. A short specification of the analytical methods utilizing the physical and chemical properties of the phenothiazine derivatives is also included.

Analytical Properties of 2- and 10-Disubstituted Phenothiazine Derivatives

Three simple spectrophotometric methods have been described for the assay of olanzapine in its pure and pharmaceutical formulations. The direct method (A) is based on the drug oxidation with excess of N-bromosuccinimide in acidic medium and the two indirect methods (B and C) are based on the oxidation of the drug with excess of N-bromosuccinimide and cerium(IV)sulfate, followed by the reaction of the unconsumed oxidants with celestine blue. The calibration graphs were linear over the range 10 - 120 µg mL-1 (method A), 0.5 - 6.0 µg mL-1 (method B) and 0.6 - 3.0 µg mL-1 (method C). After validation, the proposed methods were successfully applied to assay of olanzapine in its commercial tablets with mean percentage recoveries of 101.23 ± 0.10, 96 ± 0.10 and 94 ± 0.04%. The mechanism of olanzapine oxidation with N-bromosuccinimide was also proposed.

Spectrophotometric determination of olanzapine by its oxidation with N-bromosuccinimide and cerium(IV)sulfate.

Phenothiazines substituted in the 2 and 10 positions exhibit many valuable analytical properties. They are easily oxidized in acidic medium with a number of oxidants, e.g., K2Cr2O7, NH4VO3, Ce(SO4)2, KBrO3, KIO3, KIO4, NaNO2, H2O2, and chloramine T, with the formation of colored oxidation products. This property enable certain phenothiazines to be used as redox indicators for the determination of Fe(II), Sn(II), U(IV), Mo(V), ascorbic acid, etc. Oxidation reactions of phenothiazines were also used for their determination by spectrophotometric and flow injection methods. Some ions, such as iron, vanadium, iodide, or nitrite have a catalytic effect on the oxidation of phenothiazines. Owing to these properties several catalytic methods for the determination of metals, iodide, and nitrite have been proposed. Phenothiazines react in acidic media with platinum metals, e.g., Pd(II), Ru(III), and Pt(IV), the formation of colored complexes. They also react with thiocyanate anionic complexes of metals, e.g., Co(II)...

Analytical study of the reaction of phenothiazines with some oxidants, metal ions, and organic substances (review article)

An examination of chlorpromazine hydrochloride as indicator and spectrophotometric reagent for the determination of molybdenum(V)

Three 2,10‐disubstituted phenothiazines—chlorpromazine hydrochloride (CPM), thioridazine hydrochloride (TR) and propericiazine (PRC)—were electrochemically studied in various buffer systems at different pH values, using a glassy carbon electrode. The substances were electrochemically oxidized at potential range 0.55–0.75 V. The oxidation was reversible and exhibited diffusion‐controlled process. The mechanism of the oxidation process is discussed. According to the linear relation between peak current and concentration, differential pulse voltammetry (DPV) and square wave voltammetry (SWV) methods for quantitative determination of chlorpromazine and propericiazine in 0.1 M HClO4, and thioridazine in pH 2 phosphate buffer, was applied. Both the repeatability and reproducibility of the methods were also determined for all studied substances. The developed procedures were successfully applied to the determination of chlorpromazine and thioridazine in pharmaceutical dosage forms.

Electrochemical Oxidation of Phenothiazine Derivatives at Glassy Carbon Electrodes and Their Differential Pulse and Square‐wave Voltammetric Determination in Pharmaceuticals

Helena Puzanowska-Tarasiewicz

Papers

Analytical Properties of 2- and 10-Disubstituted Phenothiazine Derivatives

Spectrophotometric determination of olanzapine by its oxidation with N-bromosuccinimide and cerium(IV)sulfate.

Analytical study of the reaction of phenothiazines with some oxidants, metal ions, and organic substances (review article)

An examination of chlorpromazine hydrochloride as indicator and spectrophotometric reagent for the determination of molybdenum(V)

Electrochemical Oxidation of Phenothiazine Derivatives at Glassy Carbon Electrodes and Their Differential Pulse and Square‐wave Voltammetric Determination in Pharmaceuticals