Requirements Of Analytical Chemistry Research Articles

Toward a new classification Method: Fractal dimension applied to chromatographic wine data

A study of Argentine wines was carried out by direct injection of the samples without previous treatment in a high-performance liquid chromatography system coupled to a diode array detector (HPLC-DAD). The collected data, corresponding to six different varietals (Bonarda, Cabernet Sauvignon, Malbec, Merlot, Syrah, and Tempranillo), were processed with a new chemometric approach: determining the fractal dimension of principal components or fractal dimension analysis (FDA). A comparative study of the efficiency of the new proposed model to discriminate wine samples according to botanical origin was made with methods based on a linear multivariate resolution curve-alternating least squares model (MCR-ALS) previously reported. The results show that the fractal dimension analysis of the data improves the discrimination between all the varietals studied, allowing better discrimination in relation to other reported methodologies. Finally, a comparative analysis of the method’s sustainability was carried out using the Analytical Eco-Scale indicator. This analysis demonstrated that the method based on fractal analysis is a simple procedure that meets most of the Green Analytical Chemistry requirements.

Differential pulse voltammetric determination of selected nitrophenols on novel type of porous silver working electrode prepared by powder metallurgy

AbstractNitrophenols are important environmental pollutants and their monitoring is important because of their genotoxic and ecotoxic properties. Easy electrochemical reduction of nitro groups can be used for their voltammetric determination using mercury based electrodes. However, requirements of green analytical chemistry prompted us to investigate a novel type of silver porous electrode (AgPE) prepared by powder metallurgy compatible with both “green” and “white” analytical chemistry requirements. In this paper, AgPE was for the first time successfully used for differential pulse voltammetric determination of micromolar concentrations of 2‐nitrophenol (NP), 2,4‐dinitrophenol (DNP), and 2,4,6‐trinitrophenol (TNP) in aqueous media. The main advantage of the novel method is the possibility to use small sample volume (down to 25 μL) and to work in the presence of oxygen when using supporting electrolyte of pH 3. This advantage partially compensates the fact that the obtained sensitivity and limit of detection are not better than with the previously investigated electrodes.

Ionic Liquid-Assisted DLLME and SPME for the Determination of Contaminants in Food Samples

Developing effective and green methods for food analysis and separation has become an urgent issue regarding the ever-increasing concern of food quality and safety. Ionic liquids (ILs) are a new chemical medium and soft functional material developed under the framework of green chemistry and possess many unique properties, such as low melting points, low-to-negligible vapor pressures, excellent solubility, structural designability and high thermal stability. Combining ILs with extraction techniques not only takes advantage of ILs but also overcomes the disadvantages of traditional extraction methods. This subject has attracted intensive research efforts recently. Here, we present a brief review of the current research status and latest developments regarding the application of IL-assisted microextraction, including dispersive liquid–liquid microextraction (DLLME) and solid-phase microextraction (SPME), in food analysis and separation. The practical applications of ILs in determining toxic and harmful substances in food specimens with quite different natures are summarized and discussed. The critical function of ILs and the advantages of IL-based microextraction techniques over conventional extraction techniques are discussed in detail. Additionally, the recovery of ILs using different approaches is also presented to comply with green analytical chemistry requirements.

Untargeted flavor profiling of lager beers by stir bar sorptive extraction –capillary gas chromatography – time-of-flight mass spectrometry: High analytical performance with a green touch

Beer is one of the most popular beverages in the world and its complex flavor is widely appreciated. Beer flavor profiling is important for brewers to optimize beer production and to guarantee odor quality and taste stability of the final products. This is especially the case for pale lager beers that represent the beer type with the largest worldwide production volume. In this study, the combination of stir bar sorptive extraction (SBSE) with capillary gas chromatography (GC) hyphenated to time-of-flight mass spectrometry (TOFMS) was used to perform a detailed aroma profiling of lager beer samples originating from Belgium, The Netherlands, and France. A generic SBSE method was applied resulting in a very broad extraction coverage of odor solutes, while the extraction process is miniaturized, unattended and solventless, meeting green analytical chemistry requirements. Using GC-TOFMS analysis operated in untargeted mode, MS deconvolution and statistical data analysis, with principal component and hierarchical clustering analysis, it was possible to clearly differentiate brands and origins of the beer samples and to identify marker compounds for flavor profiling of these closely related beer samples. An extended database of beer aroma compounds was created. The developed method can be applied in beer quality optimization and quality control in routine laboratories.

High-throughput microscale extraction using ionic liquids and derivatives: A review.

Ionic liquids and derivatives-mainly polymeric ionic liquids and magnetic ionic liquids-have been extensively used in microscale extraction over the past few years. Current trends in analytical sample preparation gear toward linking microextraction approaches with high-throughput sample processing to comply with green analytical chemistry requirements. A variety of high sample throughput strategies that are coupled to both ionic-liquid-based solid-phase microextraction and ionic liquid-based liquid-phase microextraction are herein reported. The review is focused on microscale extraction methods that use (i) custom-made and dedicated extraction devices, (ii) parallel extraction, (iii) magnetic-based separation, and (iv) miniaturized systems employing semi-automatic or fully automatic flow injection methods, related micro/millifluidic devices, and robotic equipment.

Metal-Organic Frameworks in Green Analytical Chemistry

Metal-organic frameworks (MOFs) are porous hybrid materials composed of metal ions and organic linkers, characterized by their crystallinity and by the highest known surface areas. MOFs structures present accessible cages, tunnels and modifiable pores, together with adequate mechanical and thermal stability. Their outstanding properties have led to their recognition as revolutionary materials in recent years. Analytical chemistry has also benefited from the potential of MOF applications. MOFs succeed as sorbent materials in extraction and microextraction procedures, as sensors, and as stationary or pseudo-stationary phases in chromatographic systems. To date, around 100 different MOFs form part of those analytical applications. This review intends to give an overview on the use of MOFs in analytical chemistry in recent years (2017–2019) within the framework of green analytical chemistry requirements, with a particular emphasis on possible toxicity issues of neat MOFs and trends to ensure green approaches in their preparation.

A novel strategy for medical foods digestion and subsequent elemental determination using inductively coupled plasma optical emission spectrometry

A sample preparation method using only H2O2 in the single reaction chamber system (SRC-H2O2) for medical foods (MFs) digestion and further elemental determination by inductively coupled plasma optical emission spectrometry (ICP OES) was proposed. Digestion of some refractory substances (RS), such as, histidine, linoleic acid, phenylalanine and tryptophan, was also investigated. For the method development important parameters, such as, maximum temperature and pressure of SRC system, volume of H2O2 and sample mass were evaluated. Digestion efficiency was evaluated based on the concentration of residual carbon (RC) of final digests. The optimized method conditions were 1 g of sample, 6 mL of 50% H2O2 and maximum temperature and pressure of 250 °C and 160 bar, respectively. The digests obtained using the optimized conditions presented concentration of RC lower than 720 mg L−1. The accuracy of SRC-H2O2 method was evaluated by analysis of reference material (RM) NIST 8435 (whole milk powder) and by comparison between results obtained using the proposed method and those obtained by digestion with concentrated HNO3 (SRC-HNO3). Significant differences were not observed comparing the results of SRC-H2O2 with reference values of RM and SRC-HNO3. Limits of detection obtained by the proposed method ranged from 0.01 to 88 μg g−1 for all elements determined by ICP OES. SRC-H2O2 method provided digests of individual constituents (sodium caseinate, corn syrup and sunflower oil) of MFs and RS with residual carbon content (RCC) lower than 10% (calculated based on molar and sample masses), except for linoleic acid (RCC of 17%). These same compounds were also digested using SRC-HNO3 method and the RCC values were significantly lower than than those found by SRC-H2O2, except for aromatic amino acids (tryptophan and phenylalanine). The final acidity of digests obtained using SRC-H2O2 was negligible that is convenient for elemental determination using ICP-based techniques and agrees with green analytical chemistry requirements.

Green and fast determination of the alcoholic content of wines using thermal infrared enthalpimetry

An innovative use of thermal infrared enthalpimetry (TIE) is proposed for the determination of alcoholic content of red and white wines. Notwithstanding the presence of ethanol in beverages, absolute ethanol was added directly to wines, and the temperature rise caused by the heat of dilution was monitored using an infrared camera. Analytical signals were obtained in only 10 s for four samples simultaneously, and a calibration curve was constructed with hydroalcoholic reference solutions. A linear calibration curve was obtained from 3.0 to 18.0% (v/v) ethanol (R2 = 0.9987). The results showed agreement ranging from 98.2 to 104.0% with 942.06 and 969.12 methods of AOAC. Organic compounds (e.g., sugar) did not interfere in the determinations. The proposed method provided fast results, with a throughput of 480 samples per hour and negligible energy consumption (0.001 kWh). In addition, the consumption of reagents was reduced when compared with conventional method fulfilling green analytical chemistry requirements.

Evaluating homeopathic drugs within a biomedical framework

The concept of hormesis can provide an evaluation framework for the assessment of homeopathic treatment preparations following a post-conditioning hormesis protocol based on the research of van Wijk and colleagues. This proposal would require that doses of administered drug conform to analytical chemistry requirements for quantification. This developmental framework can provide a scientific 'point of contact' between the homeopathic and biomedical communities, which has long been lacking.

Application of gas chromatography in analysis of industrial wastes

One of the important ecological problems is how to monitor the content of volatile substances in the air of industrial buildings and installations, as thi~" is a major factor in providing safe working conditions; another important problem is the determination of the toxicity class of industrial wastes. Gas chromatography is widely used in solving these problems. For the Novokuibyshevsk Insulating Materials Plant and the Plastik Production Association (in the city of Syzran'), a procedure has been developed for the determination of ethyl and butyl acetate in workplace atmospheres. The method now used to determine acetates -- a colorimetric method -- does not meet the modern requirements of analytical chemistry with respect to accuracy and speed [1]. Gas chromatography, with preconcentration of the acetates in ethanol, is also inadequate in accuracy, owing to the volatility of the absorbing solution [2]. In developing a procedure for this purpose, we selected a method of preconcentrating the analyte substances and the conditions for chromatographic analysis of the concentrate. We chose to absorb the acetates in water, as this is the most easily available absorbing agent, and it does not require any special storage conditions. For the chromatographic analysis, conditions were selected so as to meet the requirement of quantitative determination of individual acetates in aqueous solution. The internal standard method was preferred for quantitative interpretation of the chromatograms [3]. As a comparison sample we took butanol, the solubility of which in water is higher than that of the acetates [4]. In view of the appreciable polarity of oxygen-containing compounds, we selected as a stationary phase XE-60, supported in amount of 5 % by weight on Inerton AW. The analysis was performed in a Khrom-5 chromatograph with flame ionization detectors and a packed column with a length of 2.5 m; the determinations were performed at 65-70~ Complete separation of each of the acetates and the butanol comparison standard was achieved in 6-8 rain (Fig. 1). The water (absorbing agent) does not affect the separation.

Review on problems, techniques and trends in thermal analysis

The most important problems of thermal analysis, including those of methodological nature, are reviewed critically, with regard to the special requirements of analytical chemistry. After touching on the questions of nomenclature and standardisation in thermal analysis, the construction of measuring systems and the connections between the individual parts are dealt with. The nature of information provided by thermal methods of analysis and the present state of development of data acquisition and processing in this field are described. Attention is paid to the problems involved in processing kinetic data and the difficulties of this type of data evaluation are pointed out. A relatively long chapter is devoted to the description of the individual methods, including their fields of application. Thermogravimetry and evolved gas analysis are treated with special regard to systems coupled with MS and GC. Thermomechanometry, thermosonimetry, thermoelectrometry and thermooptometry are also discussed. The paper is concluded by views concerning the future development of thermal analysis.