Assessment of greenness for the determination of voriconazole in reported analytical methods

Analytical research with adverse environmental impact has caused a severe rise in concern about the ecological consequences of its strategies, most notably the use and emission of harmful solvents/reagents into the atmosphere. Nowadays, industries are searching for the best reproducible methods. Voriconazole is a second-generation azole derivative used effectively in the treatment of Candida and Aspergillus species infections and oropharyngeal candidiasis in AIDS patients. Recently it has become the drug of choice in treating mucormycosis in several countries, which raises the need for production in large quantities. The present review deals with various recent important analytical techniques used to estimate voriconazole and its combination in pharmaceutical formulations and biological fluids. The methods show their own unique way of analyzing voriconazole in different matrices with excellent linearity, detection, and quantification limits. Additionally, this article deals with methods and solvents analyzed for their impact on the environment. This is followed by estimating the degree of greenness of the methods using various available assessment tools like analytical eco-scale, national environmental method index, green analytical procedure index, and AGREE metrics to confirm the environmental impact. The scores obtained with the evaluation tools depict the quantum of greenness for the reported methods and provide an ideal approach adopted for VOR estimation. Very few methods are eco-friendly, which shows that there is a need for the budding analyst to develop methods based on green analytical principles to protect the environment.

Evolution in miniaturized column liquid chromatography instrumentation and applications: An overview

The purpose of this article is to underline the miniaturized LC instrumental system and describe the evolution of commercially available systems by discussing their advantages and drawbacks. Nowadays, there are already many miniaturized LC systems available with a great variety of pump design, interface and detectors as well as efficient columns technologies and reduced connections devices. The solvent delivery systems are able to drive the mobile phase without flow splitters and promote gradient elution using either dual piston reciprocating or syringe-type pumps. The mass spectrometry as detection system is the most widely used detection system; among many alternative ionization sources direct-EI LC-MS is a promising alternative to APCI. In addition, capillary columns are now available showing many possibilities of stationary phases, inner diameters and hardware materials. This review provides a discussion about miniaturized LC demonstrating fundamentals and instrumentals' aspects of the commercially available miniaturized LC instrumental system mainly nano and micro LC formats. This review also covers the recent developments and trends in instrumentation, capillary and nano columns, and several applications of this very important and promising field.

Fast, comprehensive two-dimensional liquid chromatography

The absolute need to improve the separating power of liquid chromatography, especially for multi-constituent biological samples, is becoming increasingly evident. In response, over the past few years, there has been a great deal of interest in the development of two-dimensional liquid chromatography (2DLC). Just as 1DLC is preferred to 1DGC based on its compatibility with biological materials we believe that ultimately 2DLC will be preferred to the much more highly developed 2DGC for such samples. The huge advantage of 2D chromatographic techniques over 1D methods is inherent in the tremendous potential increase in peak capacity (resolving power). This is especially true of comprehensive 2D chromatography wherein it is possible, under ideal conditions, to obtain a total peak capacity equal to the product of the peak capacities of the first and second dimension separations. However, the very long timescale (typically several hours to tens of hours) of comprehensive 2DLC is clearly its chief drawback. Recent advances in the use of higher temperatures to speed up isocratic and gradient elution liquid chromatography have been used to decrease the time needed to do the second dimension LC separation of 2DLC to about 20s for a full gradient elution run. Thus, fast, high temperature LC is becoming a very promising technique. Peak capacities of over 2000 and rates of peak capacity production of nearly 1 peak/s have been achieved. In consequence, many real samples showing more than 200 peaks with signal to noise ratios of better than 10:1 have been run in total times of under 30 min. This report is not intended to be a comprehensive review of 2DLC, but is deliberately focused on the issues involved in doing fast 2DLC by means of elevating the column temperature; however, many issues of broader applicability will be discussed.

Superheated water chromatography--a green technology for the future

Reversed phase liquid chromatography using superheated water as the mobile phase, at temperatures between 100 and 250 degrees C, offers a number of advantages for the analyst. It is an environmentally clean solvent, reducing solvent usage and disposal costs. It has advantages in detection, allowing UV spectra to be monitored down to short wavelengths, as well as a compatibility with universal flame ionisation detection and mass spectroscopy. By employing deuterium oxide as the eluent, solvent free NMR spectra can be measured. The development of newer more thermally stable stationary phases, including hybrid phases, have expanded the analytes that can be examined and these now range from alkylbenzenes, phenols, alkyl aryl ketones and a number of pharmaceuticals to carboxylic acids, amino acids, and carbohydrates. Very few compounds have been found to be unstable during the analysis. The separation methods can be directly coupled to superheated water extraction providing a totally solvent free system for sample extraction and analysis.

Elevated temperature and temperature programming in conventional liquid chromatography – fundamentals and applications

Temperature, as a powerful variable in conventional LC is discussed from a fundamental point of view and illustrated with applications from the author's laboratory. Emphasis is given to the influence of temperature on speed, selectivity, efficiency, detectability, and mobile phase composition (green chromatography). The problems accompanying the use of elevated temperature and temperature programming in LC are reviewed and solutions are described. The available stationary phases for high temperature operation are summarized and a brief overview of recent applications reported in the literature is given.

Thermodynamic Prediction of Polymer Retention in Temperature-Programmed HPLC

Temperature programming has been used increasingly in liquid chromatography in recent years. In particular, temperature gradient elution has shown great potential in the analysis of complex polymers. In this study, the polymer retention behavior in temperature gradient interaction chromatography is investigated based on thermodynamic consideration of the retention factor. The polymer retention predicted by the model calculation is in good agreement with the experimental results, and the model allows devising a temperature program for designed retention behaviors such as a linear dependence of retention volume on log(molecular weight) of polymers. In addition, the migration behavior of polymeric solute along the separation column can be simulated, which shows strong molecular weight dependence. The migration behavior is also confirmed experimentally by employing different length columns or delayed injection.

Rapid molecular weight analysis of polymers by temperature gradient interaction chromatography

Temperature gradient interaction chromatography (TGIC) has been established as a high-resolution technique for the characterization of synthetic polymers. So far, most of the TGIC investigations focused on the high-resolution analysis and little effort has been made on the reduction of the analysis time. In this study, we examined the effect of the column heating rate, the eluent flow rate, and the column length on the TGIC analysis time. We found that the heating rate is the most important experimental parameter to control the TGIC retention time. With a C18 silica column (50 mm x 4.6mm I.D.), a set of PS standards of wide molecular weight range (5 - 648 kg/mol) could be separated within 4 min at a heating rate of 8 degrees C/min.

Use of temperature programming to improve resolution of inorganic anions, haloacetic acids and oxyhalides in drinking water by suppressed ion chromatography

Temperature programming was used to improve selectivity in the suppressed ion chromatographic (IC) separation of inorganic anions, haloacetic acids and oxyhalides in drinking water samples when using NaOH gradient elution. The programme exploited varying responses of these anions to changes in temperature. Heats of adsorption (deltaH, kJ/mol) for 17 anionic species were calculated from van't Hoff plots. For haloacetic acids, both the degree of substitution and log P (log of n-octanol-waterpartition coefficient) values correlated well with the magnitude of the temperature effect, with monochloro- and monobromoacetic acids showing the largest effect (deltaH= -10.4 to -10.7 kJ/mol), dichloro- and dibromoacetic acids showing a reduced effect (deltaH= -6.8 to -8.4 kJ/mol) and trichloro-, bromodichloro- and chlorodibromoacetic acids showing the least effect (deltaH= -4.7 to -2.4 kJ/mol). The effect of temperature on oxyhalides ranged from deltaH= 8.4 kJ/mol for perchlorate to deltaH= -9.1 kJ/mol for iodate. The effectiveness of two commercial column ovens was investigated for the application of temperature gradients during chromatographic runs, with the best system applied to improve the resolution of closely retained species at the start, middle and end of the separation obtained using a previously optimised hydroxide gradient, in a real drinking water sample matrix. Retention time reproducibility of the final method ranged from 0.62 to 3.18% RSD (n = 30) showing temperature programming is indeed a practically important parameter to manipulate resolution.