Current Analytical Chemistry - Volume 12, Issue 4, 2016

This paper describes the possible implementation of the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) as green analytical chemistry metrics tools. TOPSIS is one of the multi-criteria decision analysis (MCDA) tools that is applied in the selection of the best alternative from many possible. In this case we have applied it to assess the nineteen analytical procedures for ibuprofen determination in wastewater samples. They were described by the eight different criteria, such as metrological, economic and environmental ones. We applied the weights for each criterion that were obtained from experts knowledge. The results were discussed by the examples of six different scenarios derived by application of TOPSIS technique. Relative importance of criteria depends on subjective estimation of the decision maker and has a significant influence on the final result. TOPSIS is useful tool in assessment of green analytical chemistry metrics and ranking of the alternatives. It is very straightforward in use, it can be easily implemented in Excel program. The results are numerical values that make the results very simple to interpret and compare.

Sample preparation is a crucial step in the analytical process. The solid phase absorbents attracted more interest in research on the preparation of samples, because they have a crucial role in achieving a high effectiveness of the purification and enrichment in the analysis of trace compounds present in complex matrices. Carbon nanotubes (CNTs) exhibit unique properties for a variety of processes and applications. The combination of structure, dimensions and topology allow for their use in Analytical Chemistry, primarily as a matrix in a matrix assisted laser desorption ionization, stationary phase in both gas chromatography (GC) and high performance liquid chromatography (HPLC) and as sorbents in solid phase extraction (SPE). The aim of this review is to provide a broad overview of recent applications of CNTs for the isolation of pharmaceuticals from environmental, biological and food samples before chromatographic analysis, in the period from 2006 to 2015.

Pharmaceutical residues in the environment is a field of special interest due to the adverse effects to either human health or aquatic and soil environment. Pharmaceuticals have been already detected in underground, surface and wastewaters, soils, manure and sediments. The growing awareness of environmental pollution arising from human activity forces the need for their comprehensive determination. Environmental samples are complex matrices to analytical chemists. The biggest problem encounters is that multiple contaminants exist in the environment at the trace levels, at the parts-perbillion (μg L-1) and parts-per-trillion (ng L-1) concentration levels. The need to obtain reliable results, for determining the content of micropollutants became the driving force behind the development of modern analytical techniques. This chapter addresses sample preparation techniques that can be applied for the analysis of pharmaceuticals in environmental samples. The main focus has been paid on: SPE, MEPS, SBSE, MSPD, FPSE, DLLME and QuECh- ERS. In addition, recent examples of applications of these techniques and examples of promising sorbents like carbon nanotubes, graphene oxide, and graphite are presented. Future trends for sample preparation techniques are highlighted.

The issue of drug chirality is attracting increasing attention among the scientific community. The phenomenon of chirality has been overlooked in environmental research (environmental occurrence, fate and toxicity) despite the great impact that chiral pharmacologically active compounds (cPACs) can provoke on ecosystems. The aim of this paper is to introduce the topic of chirality and its implications in environmental contamination. Special attention has been paid to the most recent advances in chiral analysis based on liquid chromatography coupled with mass spectrometry and the most popular protein based chiral stationary phases. Several groups of cPACs of environmental relevance, such as illicit drugs, human and veterinary medicines were discussed. The increase in the number of papers published in the area of chiral environmental analysis indicates that researchers are actively pursuing new opportunities to provide better understanding of environmental impacts resulting from the enantiomerism of cPACs.

Environmental pollutants that disrupt endocrine functions, such as natural and synthetic estrogens, can significantly compromise the ecological and biological balance of ecosystems, in particular aqueous habitats. Long-term exposure to endocrine disruptors has adverse effects on water organisms and, consequently, humans. In nature, estrogens occur at very low concentrations, and their presence in environmental samples is very difficult to confirm. Selective and repeatable methods for preparing aqueous samples and reliable separation and identification techniques are required to accomplish the above task. Molecularly imprinted solid-phase extraction (MISPE) polymers are popularly used for the preparation of water samples. This article overviews the existing knowledge about sample preparation methods, with special emphasis on the progress made in the synthesis of molecularly imprinted polymers as effective sorbents for isolating estrogens from environmental and biological samples. The latest technological solutions, including molecularly imprinted polymer nanoparticles, are discussed as potential methods for isolating selected analytes. The challenges and prospects associated with new selective sorbents are also discussed.

Hydrolysis is one of the most important abiotic processes leading to the degradation of organic compounds in aqueous media. Although there have been many reports concerning the biodegradability or photostability of the investigated compounds, much less information is available on their hydrolytic stability. Moreover, hydrolysis rates have been established using procedures other than the recommended standardized OECD 111 procedures. This standard ensures that 1st category reliability data for the ERA of pharmaceuticals is obtained. Therefore, in this study we have applied optimized analytical procedures utilizing HPLC for determination of degradation rates in aqueous environment of ciprofloxacin (CIP), norfloxacin (NOR), enrofloxacin (ENR) and metronidazole (MTZ). This study, aims to assess hydrolytic stabilities of these compounds, which are the four most commonly used pharmaceuticals. The developed procedures let us determine all of the analyzed pharmaceuticals in various pH values of solution, over three times magnitude linearity ranges, high precision (RSD % <8.2) as well as detection limits in the range of 0.007 to 0.033 mg L-1. Obtained analytical performance parameters enabled us to track in details hydrolytic kinetics even of the very low concentrations. The results clearly showed that the hydrolytic degradation of tested pharmaceuticals is below 10% in a pH range from 4 to 9. This means that the half-lives of these compounds in an aquatic environment are higher than 1 year at 25 °C. Thus, hydrolytic pathways do not lead to a fast degradation and reduced risk of persistency for the investigated compounds.

A simple, precise and rapid conductometric titration method for determination of phenylephrine-HCl in pharmaceutical formulations by using, bismuth (III) tetraiodide as precipitating agent has been described. The proposed method was based on the formation of ion-pair associate between PHE and the inorganic complex, bismuth (III) tetraiodide to form an orange- red precipitate with PHE and the conductance of the ion-pair solution was measured as a function of the volume of titrant. Different factors affecting the reaction have been evaluated to obtain the best results. The studied drug was evaluated in deionized water in the range of 0.4-2.5 mg (8-50 μg/ml) PHE. The results were in good agreement with those obtained by the reference method.

Separation of five β-blocker 1-fluoro-2,4-dinitrophenyl-5-L-valine amide (FVDA) derivatives i.e. acebutolol, atenolol, metoprolol, oxprenolol and pindolol by means of high-performance thin layer chromatography (HPTLC) as well as pressurized planar electrochromatography (PPEC) techniques and with the use of HPTLC RP-18W plates as well as the acetonitrile - buffer mobile phase is presented. The influence of concentration of acetonitrile and pH of the mobile phase buffer, and temperature on migration distance of the solute zones was investigated. It has been observed that an increase of acetonitrile content of the mobile phase affects the solute zone migrations and retentions in HPTLC and PPEC. Whereas rise of eluent buffer pH enhances predominantly the isomer migration distances in PPEC. The temperature increase results the enhancement of solute migration distances in PPEC and diminishes isomer retention in HPTLC. Moreover, it improves the diastereomer pair zones resolution in both investigated systems. What is more, the separation selectivity in PPEC and HPTLC system differs. The former system presents higher efficiency in comparison with the latter. In addition separation of FVDA-oxprenolol and FVDA-pindolol isomers is presented for the first time.

Background: Tissue amino acids are important markers to characterize (patho)physiology. As neurotransmitters or their precursors, they have special significance in brain. However, mass spectrometry (MS)-based quantifications of brain amino acids are rare and inconsistent. Methods: To reveal efficient procedures optimal for brain research purposes, free amino acids in the same extracts of rat cerebellum were quantified by published assays employing hybrid triple quadrupole-linear ion trap (QTRAP) MS or amino acid analyzer with ninhydrin derivatization. Results: Levels of four amino acids out of 14 quantified by the two methods were established to be perturbed in the QTRAP MS assay, with the ninhydrin-based quantification agreeing well with the published values obtained by non-MS approaches. The overestimation of Glu and Lys and underestimation of Gly and Tyr in brain extracts by QTRAP MS suggest interference of the co-eluting compounds and ion suppression effects, correspondingly. The MS-inherent artifacts presumably contribute to inconsistency of published MS data on the brain amino acid content, as our analysis of different studies indicated that the variability of the MS data greatly exceeds the biological variability. Conclusion: Evaluation of potential artifacts of the MS-based quantification of brain amino acids using the ninhydrin detection as a reference method, provides a solution for reliable quantification of the artifact-resistant amino acids, pointing to relatively good performance of the time- and cost-efficient QTRAP MS procedure employed.

Background: The corrosion of oil pipeline and equipment could lead to serious and technological problems. As the superior characteristics of inhibitor such as lower dosage and effective, corrosion inhibitor is widely applied to various fields. The aims of this paper are to mainly investigate the corrosion inhibition efficiency of β-cyclodextrin functionalized acrylamide copolymer (HCMPAM) on X70 steel in 0.5 M H2SO4 solution under different HCMPAM concentrations and different temperatures. Methods: The inhibition efficiency of copolymer on X70 steel in 0.5 M H2SO4 solution utilizing polarization, electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The inhibition efficiency of β-cyclodextrin functionalized acrylamide copolymer increases with the increase of concentration and decreases with the increase of temperature, the inhibition efficiency of HCMPAM exhibited the maximum values (94.8%) at the highest concentration of 150 mg L-1 at 293 K. Conclusion: HCMPAM copolymer acts as a mixed-type inhibitor, the inhibition efficiency increases with the increase of concentration and decreases with the increase of temperature. The adsorption of HCMPAM on X70 steel is found to obey the Langmuir isotherm and governed by chemisorptions. The adsorption of HCMPAM on X70 steel in 0.5 M H2SO4 solution was an exothermic process. The SEM and EDS results reveal that X70 steel form a protective layer and prevent the attack of acid on X70 steel surface.

Background: Bee pollen, a type of floristic pollen collected by honeybees, is extracted at the hive entrance using a pollen trap, and had mixed with saliva and gland secretions. Considering its natural origin, pollen may be contaminated with pollutants due to hidden environmental factors and extensive application of pesticides. Because of their environmental persistence and prevalence in various environmental mediums, POPs can be encountered by forage bees and carried back to hives. The aim of the present study was to develop an analytical method for simultaneous determination of trace levels of 16 PAHs, 14 OCPs and 7 PCBs in bee pollen. Methods: A new method was developed using QuEChERS/GC-MS. For the initial extraction step, QuEChERS Extract Tubes based on the AOAC method for the acetate-buffered version were used. The following tubes were used for the subsequent cleanup step: dispersive tubes. Results: Recoveries of target analytes under optimized conditions ranged from 51.3% to 138.8%. Limits of detection and limits of quantification were lesser or equal to 5.8 and 19.2 μg/kg, respectively. The correlation coefficients of 37 target analytes were higher than 0.99. This study lays the foundation for the further research into bee pollen as an environmental indicator. Conclusion: The method is simple, economical, effective and robust for simultaneous analysis of 37 kinds of POPs in bee pollen matrix. The degree of environmental pollution could be evaluated by analyzing the pollutants in bee pollen samples. This study lays the foundation for the further research into bee pollen as an environmental indicator.

Introduction: More than 20 ppm of Zn2+ impurities in Ni electroplating baths causes Ni coating anticorrosive and decorative properties degradation. The 105 excess of Ni2+ concentration however interferes the Zn2+ impurities quantification allowing correcting the Ni bath concentrations. Objectives: The objective of this work is the development, characterization and testing with real samples of a rapid and simple voltammetric method for automated on-line Zn2+ quantification in the presence of 105 excess of Ni2+. Methods: The proposed analytical method is based on the Zn2+ability to form soluble hydroxyl complexes in excess of OH-, while Ni2+ precipitates at these conditions. Zn2+ remaining in the liquid phase was determined by applying Differential Pulse Voltammetry (DPV). Results: The analytical characteristics of the developed DPV method were found to be the following: LOD 40 ppb; linear concentration range up to 32 ppm; relative errors from 2.21% to 8.74%. Conclusion: A voltammetric method for on-line automated Zn2+ impurities quantification in 105 excess of Ni2+ was developed, characterized, and finally tested with real industrial samples by comparison with ICP applied after Zn2+ extraction. The results deviation obtained by the two methods was less than 6.25% in the range from 3.2 to 14.7 ppm Zn2+.