Vol 71, No 9 (2016)

This review article summarizes the opportunities for utilizing the green analytical chemistry (GAC) techniques and principles in the field of quality control (QC) of pharmaceuticals. Green analytical chemistry is considered a branch of the green chemistry based on the principles overlapping with the goals of sustainable development. General definitions of quality and quality control, the principles of GAC, proposals for greener sample pretreatment and greener chromatographic method of analysis applied in QC laboratories are discussed herein. The main goal is to achieve more eco-friendly analysis in QC laboratories through different strategies and techniques, replace toxic reagents, and modify or replace analytical methods and/or techniques with safer ones, making it possible to dramatically reduce the amounts of reagents consumed and waste generated.

An experimental dependence of the relative standard deviation on analyte concentration of hyperbolic type, characterizing the precision of quantitative chemical analysis, was used to estimate the limits of detection and determination in the X-ray fluorescence analysis. A method is proposed for the determination of their values using the approximation of the experimental dependence of the relative standard deviation on the analyte concentration by a power function. The choice of the values of the relative standard deviation, being criteria for the estimation of these limits, is substantiated. A concept of the limits of detection and determination of an analytical procedure is formulated, according to which the limit of detection of an analytical procedure is an objective value depending only on the precision of determinations, and the limit of determination of an analytical procedure is a subjective value depending not only on the precision of determinations but also on the requirements to their limiting (admissible) accuracy. The limits of detection and determinations of an analytical procedure found by this approach completely characterize the possibilities of an analytical procedure in determining low concentrations of analytes. The proposed approach can be used for the estimation of the limits of detection and determination of analytical procedures and in other methods of chemical analysis with the hyperbolic dependence of the relative standard deviation on the analyte concentration.

A method and a device are proposed for varying optical path lengths of cells for spectrophotometers by placing parallel-plane insert plates (PPIPs) of variable thickness inside the cell. This method allows (a) the rapid adjustment of the optical path length of a standard cell (a dual PPIP set 5, 2 (2 pieces), and 1 mm thick ensures the variation of the optical path length of a 10-mm cell from 1 to 10 mm with a step of 1 mm); (b) mixing of solutions in cells; and (c) simple and quick washing of cells and PPIPs in routine spectral measurements.

Reactions of palladium(II) and rhodium(III) with dithizone (DT) on polyacrylonitrile fiber filled with an AV-17 anion exchanger (PANV–AV-17) and 1-(2-pyridylazo)-2-naphthol (PAN) immobilized on polyacrylonitrile fiber filled with a KU-2 cation exchanger (PANV–KU-2–PAN) are studied by diffuse reflection spectroscopy. Conditions of rhodium complexation on PANV–KU-2–PAN (ascorbic acid concentration, pH of solution in adsorption, and the duration of heating samples) and palladium complexation with DT after adsorption from a 0.1 M NaCl solution (pH 2) on PANV–AV-17 in the dynamic mode are found. The limits of detection for rhodium and palladium are 10 and 5 ng/mL, respectively. At 640 nm, the calibration graphs are linear in the ranges of palladium and rhodium concentrations 0.008–0.06 µg/mL and 0.02–0.2 µg/mL, respectively. The mutual influence of rhodium and palladium is studied. It is shown that the determination of palladium with DT on a PANV–AV-17 solid phase is not affected by the presence of a 5-fold amount of rhodium, and rhodium can be determined on PANV–KU-2–PAN at 590 nm in the presence of 2-fold amounts of palladium.

The adsorption and selective properties of aluminum-based planar microcolumns filled with the Carbopack B adsorbent are studied. The effect of geometrical parameters of the columns on their chromatographic properties is considered on an example of the separation of a mixture of light hydrocarbons. The advantages of planar microcolumns compared to conventional packed chromatographic columns are revealed.

A new, simple, and fast method is described for determining selenium based on a silver wire electrode flow-through voltammetric detector. A comparison was done between the sensitivity of disk silver, mercury-modified glassy carbon, and mercury-modified gold electrodes. The response of the flow-through voltammetric detector was evaluated with respect to each electrode’s operating potential and pH in direct current mode. The limit of detection (3s) for Se(IV) was below 0.01 mg/L. The flow-through system does not need deposition times and the organic matter does not need to be removed before determining selenium in river water.

The expedience of the target-specific control of the properties of a medium (using micellar and aqueous–organic media), in which an indicator process providing the background for the operation of a spectrophotometric sensor based on a polyelectrolyte complex (horseradish peroxidase–chitosan) is conducted, is shown experimentally and proved by calculations of kinetic parameters of the enzymatic reaction. The application of the sensor ensures an increase in the sensitivity of the determination of peroxides of different nature and structures (e.g., hydrogen and urea peroxides, benzoyl peroxide, 2-butanone peroxide and tertbutyl hydroperoxide) in complex matrixes. The proposed approach allows the analyst not only to regulate the performance characteristics of the developed procedures for the determination of peroxides depending on the analytical task, but also to extend the range of test samples (including those insoluble in water) analyzed with no sample preparation.

A fluorescence polarization immunoassay (FPIA) procedure is developed for the determination of 2,4-dichlorophenoxyacetic acid in cereal grains using a Sentry-200 portable device. We synthesized tracers, that is, antigens labeled with fluorescein derivatives, based on two fluorescent compounds and two chlorophenoxyacids. The tracer synthesized from 2,4-dichlorophenoxyacetic acid and 4-aminomethylfluorescein is found to be optimal for the FPIA of 2,4-dichlorophenoxyacetic acid. The limit of detection for 2,4-dichlorophenoxyacetic acid in flour was 40 ng/g; the analytical range is from 80 to 1000 ng/g. The percentage of recovery was 85 ± 7% at the relative standard deviation (RSD) 2–10%.