To expand the analytical capabilities of the digital image colorimetry method, a set of technical and methodological techniques for determining the composition of one- and two-component systems using a smartphone camera and an office flatbed photoscanner is developed. Effective methods for controlling the amount of light entering the radiation receiver are selected for these consumer optical devices to carry out measurements in its linear response range. The measure of the directional influence on the exposure of an image sensor, as well as the level of scattered radiation entering it, is functionally related to the analytical signal proposed in this paper, which linearly depends on the concentration of the substance to be determined in a wide range of values. Correction of the analytical signal is based on selective extraction of data from a series of images obtained by varying the exposure of a multichannel radiation receiver. Regression models were chosen for the calculation, which allow us to take into account the mutual influence of different color channels of an image sensor equipped with a Bayer array of broadband absorption filters. Prototypes of cheap universal do-it-yourself-boxes are created to analyze solutions in a 96-well microplate using a smartphone camera and an office flatbed photoscanner. When using these boxes, the contribution of scattered radiation to the measured signal does not exceed the digital noise level of the radiation receiver. The high dynamic range digital image colorimetry method developed in the work makes it possible to determine colored substances in solution in the range of contents of more than two orders of magnitude with an error of less than 10-15 %. Its validity was proven in the analysis of model dye mixtures and carbonated beverages, as well as in the analysis of a metal alloy. The accuracy of the determination results was confirmed by the spectrophotometric method.

The work on the use of household color-recording devices for chemical analysis over the past 15 years are systematized. The methodological techniques used to improve the metrological characteristics of the digital colorimetry method at various stages of analysis are described. The conditions for the formation of an analytical signal are considered, complex approaches to expanding the analytical capabilities of digital colorimetry are discussed in detail.

A method of digital colorimetric determination of ammonium and nitrate in soils is proposed. The method is based on corresponding photometric techniques of ammonium and nitrate determination after potassium chloride extraction from soils samples. Ammonium is determined as an indophenol dye, and nitrate is determined as an azo dye. The original techniques were modified to overcome the lower sensitivity of the digital colorimetric method. For ammonium determination, the time required for the reaction to proceed completely was studied. Along with the use of a 96-well microplate protected from ambient light by a special frame, mathematical correction of scattered radiation using black ink and taking the images by a scanner in transmission mode without any post-processing, the resulting colorimetric techniques proved to provide accuracy and sensitivity close to those of the spectrophotometric techniques, and the overall analysis speed for tens of samples was even higher. The techniques’ validity was proven by the analysis of standard samples and by the analysis of soil samples collected in several districts of the Moscow region.

Обсуждены место и роль аналитической химии в системе фармацевтического образования среди других изучаемых дисциплин при подготовке специалистов-провизоров. Представлена общая структура и идеология практикума, рассмотрена специфика лабораторных работ по аналитической химии для студентов фармацевтической специальности факультета фундаментальной медицины Московского государственного университета имени М.В. Ломоносова. Разработаны, апробированы и внедрены в учебный процесс новые задачи для практикума по химическим и инструментальным методам, посвящённые анализу широко распространённых фармацевтических препаратов. Предложенный подход соответствует общей парадигме курса с его ориентацией на дальнейшую профессиональную деятельность учащихся и позволяет повысить интерес студентов к изучаемой дисциплине.

A technique for the indirect determination of the hydrogen index of aqueous solutions of small volumes (ranging from microliters to hundreds of microliters) by digital colorimetry with the use of consumer optical raster imaging devices is proposed. Determining the pH does not require constant color scales or information about the concentration of the acid-base indicator in the solution. A prototype of a handheld pH analyzer, based on a smartphone, is developed for out-of-laboratory applications. The accuracy of the pH determination results is confirmed by the potentiometry and spectrophotometry techniques.

Представлен краткий обзор методов, используемых в фармации для качественного экспресс-­анализа лекарственных препаратов. Систематизированы методы идентификации действующих веществ в аптечных условиях. Проведено сравнение аналитических возможностей методов, указаны их преимущества и ограничения. Отмечены перспективы развития тест-методов для контроля подлинности лекарственных средств. Особое внимание уделено различным вариантам цветометрии, которые в будущем могут стать одними из основных методов быстрого контроля подлинности лекарственных препаратов и мониторинга их качества.

The review systematizes works completed in the last 15 years on the application of digital (computer) colorimetry for chemical and pharmaceutical analysis. The characteristics of consumer optical devices for measuring an analytical signal are compared. The analytical possibilities and areas of application of multisensor colorimetry are discussed. The main trends and prospects for the development of the method in pharmacy are noted.

New approach to spectrophotometric and colorimetric determination of meloxicam, lornoxicam, tenoxicam in drugs using 7-chloro-4-nitrobenz-2-oxa-1,3-diazole (NBD chloride) is developed. The techniques are based on alkaline hydrolyses of oxicams with NBD chloride and the subsequent spectrophotometric and colorimetric determination of the colored products of reaction. The linearity range of calibration dependence is 1-10 mg/ml for lornoxicam and tenoxicam, 0.5-5 mg/ml for meloxicam. The advantages of developed methods are rapidity and cost-efficiency. This approach can be used for screening control of drug quality.

Technically simple and extremely cheap setups for colorimetric and fluorimetric analyses using a smartphone camera are presented. Laboratory activities on digital colorimetric and fluorimetric analyses for students of secondary and higher educational institutions are proposed, namely, photocolorimetric determination of acetylsalicylic acid in Cardiomagnyl and copper and nickel in nickel–silver alloy, and fluorimetric determination of riboflavin mononucleotide in its injection solution. Nickel and copper in nickel–silver are determined simultaneously; i.e., two-component colorimetric analysis is performed, which allows the introduction of linear regression analysis to students. The use of the developed setups and activities can help to form the students’ skills of a meaningful choice of the conditions for measuring the analytical signal to achieve the required metrological characteristics of the determination results.

Several types of patina can be formed on copper and copper-containing artefacts during ageing. These patinas prevent further destruction and, besides, can provide information about the environment conditions, under which these artefacts have been stored. In contrast, chloride corrosion is harmful for copper and bronze objects and can lead to their complete destruction. Therefore, it should be detected as early as possible. In this work, a copper coin minted in the Russian Empire in the XVIII century was investigated using micro X-ray fluorescence spectrometry. It proved to be an effective tool for the patina and contamination analysis and chloride corrosion detection.

A simple and affordable method is developed for the simultaneous determination of high concentrations of copper(II) and nickel(II) in an aqueous solution in the form of colored aqua complexes by digital colorimetry using an office flatbed photo scanner. The validity of the proposed approach is proved by the analysis of the standard nickel silver sample. The accuracy of the results of determining copper and nickel in a metal alloy by digital colorimetry and spectrophotometry differs insignificantly.

The aim of this study is to develop a universal, rapid and affordable method for the identification of dydrogesterone, troxerutin, and ademetionine in drugs by multisensor digital colorimetry using a unique two-dimensional code. The developed approach can be applied to rapid detection of counterfeit drugs at the preliminary stage of the analysis (before using more expensive specialized equipment).Materials and methods. To implement the proposed approach, the substances of dydrogesterone (“Abbott Biologicals B.V.”, Netherlands), troxerutin (JSC “Interfarma”, Prague, Czech Republic) and ademetionine (LLC “Farmamed”, Moscow, Russia), troxerutin capsules 300 mg (LLC “Pranafarm”, Samara, Russia), lyophilisate for an intravenous solution and the intramuscular administration “Heptral”® (ademetionine) 400 mg (“Abbott Laboratories”, GMBH, Germany), tablets “Duphaston”® (dydrogesterone) 10 mg (“Abbott Healthcare Products B.V.”, Netherlands), were used. A multisensor colorimetry method has been implemented using the following set of 8 sensors (C1-C8): an intact solution – a 96% (v/v) aqueous ethanol solution – C1; 1 mM alcoholic solution of anthraquinone green (CAS#4403-90-1) – C2; a 0.2% aqueous solution of 3-methylbenzothiazolinone hydrazone (CAS#1128-67-2) – C3; a 0.2% methyl orange aqueous solution (CAS#547-58-0) – C4; a 1 mM alcoholic solution of sulforhodamine B (CAS#3520-42-1) – C5; a 1 mM alcoholic solution of 1-hydroxypyrene (CAS#5315-79-7) – C6; 1 mM alcoholic solution of allura red AC (CAS#25956-17-6) – C7; a 1 mM aqueous solution of iron (III) chloride – C8. Transparent flat-bottomed polypropylene plates with 96 cells, with a cell volume of 350 µl (Thermo Fischer Scientific, USA, cat. No. 430341) were used as a base for the chip. For obtaining raster images, an Epson Perfection 1670 office flatbed scanner (CCD-matrix) with a removable cover was used. The obtained digital images of the cells were processed using the ImageJ software (Wayne Rasband, National Institutes of Health, USA; http://imagej.nih.gov/ij) with a 24-bit RGB color model (8 bits per channel).Results. The adequacy of the developed approach was confirmed by the analysis of the above-listed drugs. It has been shown that the results obtained have no statistically significant differences from the values determined by the spectrophotometric method.Conclusion. The possibility of using multisensor digital colorimetry for pharmaceutical analysis has been shown. The developed methods for the identification of the active substances can serve as a good supplement to the more expensive traditional methods.

X-ray fluorescence is one of the best approaches for nondestructive elemental analysis and is consequently widely used in industry and science. Among the main problems for its application are matrix effects and a significant content of unidentified undetectable light elements, which influence the results and may be difficult to take into account. Several approaches have been proposed for solving these problems, including those based on the use of intensity ratios and the primary radiation scattered by the sample, which often allow one to achieve satisfactory accuracy using only a few reference samples. The goal of this review is to compare these approaches, discuss their advantages and disadvantages, and highlight the prospects for their further development.

Introduction. Digital colorimetry is one of the available and simple methods that can be used for the rapid detection of low-quality drugs. The main limitation of the method is its lack of selectivity. To increase the selectivity, the use of molecular sensors is proposed. Molecular sensors are substances that change color during physicochemical interaction with the analyte. Digital colorimetric analysis using a set of sensors allows one to obtain a large amount of information about the sample, however, such a significant amount of data is rather difficult to interpret and use for rapid assessment of the composition of the drug. In addition, the use of a large set of sensors significantly increases the level of information noise. To reduce the influence of the noise component, as well as to reduce the dimensionality of the data, it is advisable to use chemometric algorithms, in particular, the method of principal components (principal component analysis, PCA). It is shown that the using of PCA will make it possible to replace 24 values of the luminosity of color channels with 2-3 numerical values of the main components without loss of analytical information.Aim. Aim of our investigation is the development of a new approach to identifying non-steroidal anti-inflammatory drugs using multisensory digital colorimetry by the principal component method.Materials and methods. The analysis was performed in 96-well transparent polypropylene plates with flat bottom (Thermo Fischer Scientific, USA, № 430341). 100 μl of the correspond-ing sensor and 100 μl of alcohol solutions of non-steroidal anti-inflammatory substance sub-stances were consistently added to the wells of the plate. Sensor solutions were added to a separate row of wells for comparison without adding substance solutions (intact wells). After adding solutions of the substance, the plate was sealed with a film, shaken on a PST-100HL plate shaker (BioSan, Latvia) for 5 minutes and left for 20 minutes to complete the reaction. To obtain raster images an Epson Perfection 1670 office flatbed scanner (CCD matrix) with a removable cover was used. The difference in the lightness of the color channels between the analyte well and the intact well was used as an analytical signal. The obtained digital images of the cells were processed in the ImageJ program using the RGB 24 bit color model (8 bits per channel).Results and discussion. It is shown that the use of chemometric algorithms for processing the results of multisensor colorimetric analysis allows to use the entire data array in obtaining an-alytical information, and not just the lightness values of individual channels of some sensors. The method of principal components allows you to simultaneously get rid of the noise com-ponent of the colorimetric signal and highlight the most sensitive sensors for this sample. The adequacy of the proposed combined approach is confirmed by the identification of active sub-stances in 5 drugs of the group of non-steroidal anti-inflammatory drugs.Conclusion. The approach proposed in this work can be successfully applied as an express and available way to assess the authenticity of medications of the group of non-steroidal anti-inflammatory drugs.

X-ray fluorescence is one of the best approaches for nondestructive elemental analysis and is consequently widely used in industry and science. Among the main problems for its application are matrix effects and a significant content of unidentified undetectable light elements, which influence the results and may be difficult to take into account. Several approaches have been proposed for solving these problems, including those based on the use of intensity ratios and the primary radiation scattered by the sample, which often allow one to achieve satisfactory accuracy using only a few reference samples. The goal of this review is to compare these approaches, discuss their advantages and disadvantages, and highlight the prospects for their further development.

An effective, affordable, and rapid method for the analysis of drugs based on chloramphenicol is developed using multisensory digital colorimetry. The use of a two-dimensional code for the identification and quantification of chloramphenicol with the minimum level of informational noise is proposed. The principal component analysis is used to increase the reliability of the results of the determination of the medicinal substance. The adequacy of the developed approach is confirmed by the analysis of chloramphenicol preparations in the form of two dosage forms: tablets and eye drops. The accuracy of the results is confirmed by the standard addition method. The results prove that the preparations do not have statistically significant differences from the values declared by the manufacturer.

An algorithm for total reflection X-ray fluorescence analysis of samples containing significant amounts of light elements with Z < 11, which are difficult to detect, is proposed based on the use of X-ray fluorescence intensity ratios. Such relative signals are much less influenced by the actual shape of a specimen and its mass, thus providing more accurate results of analysis. A Rayleigh-to-Compton scattering intensity ratio depends on the light elements total content, which thus can be evaluated. That a theoretical calibration equation describing a dependence of the Rayleigh scattering intensity on the sample's mass can be applied to the sample mass determination is demonstrated. A fundamental parameter analysis algorithm is designed that minimizes a need for external or internal standards. Its validity is proved by analysis of highly mineralized water samples.

The simple and available technique of determination of tetracycline in the form of colored complex with iron(III) ions and B12 vitamin in the form of the colored thiocyanate complex of cobalt(II) after a chemical mineralization of cyanocobalamin is offered. The analytes were separated from the accompanying components by sorption to polyurethane foam based on ethers. The conditions of sorption separation and measurement of analytical signal of these substances are optimized. The obtained results are in satisfactory agreement with data declared by the manufacturer. The adequacy of proposed approach is confirmed by results of indirect X-ray fluorescence analysis of tetracycline drug substance and injection solution B12 vitamin (cyanocobalamin).