• Energy Research

It is now recognized that analytical chemistry must also be a target for green principles, in particular chromatographic methods which typically use relatively large volumes of hazardous organic solvents. More generally, high performance liquid chromatography (HPLC) is employed routinely for quality control of complex mixtures in various industries. Acetonitrile and methanol are the most commonly used organic solvents in HPLC, but they generate an impact on the environment and can have a negative effect on the health of analysts. Ethanol offers an exciting alternative as a less toxic, biodegradable solvent for HPLC. In this work we demonstrate that replacement of acetonitrile with ethanol as the organic modifier for HPLC can be achieved without significantly compromising analytical performance. This general approach is demonstrated through the specific example analysis of a complex plant extract. A benchmark method employing acetonitrile for the analysis of Bidens pilosa extract was statistically optimized using the Green Chromatographic Fingerprinting Response (GCFR) which includes factors relating to separation performance and environmental parameters. Methods employing ethanol at 30 and 80°C were developed and compared with the reference method regarding their performance of separation (GCFR) as well as by a new metric, Comprehensive Metric to Compare Liquid Chromatography Methods (CM). The fingerprint with ethanol at 80°C was similar to or better than that with MeCN according to GCFR and CM. This demonstrates that temperature may be used to replace harmful solvents with greener ones in HPLC, including for solvents with significantly different physiochemical properties and without loss in separation performance. This work offers a general approach for the chromatographic analysis of complex samples without compromising green analytical chemistry principles.

As fossil-based resource depletion intensifies and the use of lignocellulosic biomass gains more and more momentum for the development of biorefineries, the production of furans has received a great deal of attention considering their outstanding synthetic possibilities. The production of 5-hydroxymethylfurfural (HMF) is quite established in the recent scientific literature, with a large number of studies having been published in the last few years. Lately, there has been a growing interest in the synthesis of 5-chloromethylfurfural (CMF) as a novel building block of similar molecular structure to that of HMF. CMF has some advantages, such as its production taking place at milder reaction conditions, a lower polarity that enables easier separation with the aid of organic media, and the presence of chlorine as a better leaving group in synthesis. Precisely the latter aspect has given rise to several interesting products to be obtained therefrom, including 2,5-dimethylfuran, 2,5-furandicarboxylic acid, and 5-methylfurfural, to name a few. This work covers the most relevant aspects related to the production of CMF and an array of synthetic possibilities. Through varied catalysts and reaction conditions, value-added products can be obtained from this chemical, thus highlighting the advances in the production and use of this chemical in recent years.

This work presents the development of a strategy that integrates multivariate statistical analysis and concepts of green chemistry to obtain the chromatographic profile of Brazilian red wines by HPLC-PAD. An initial screening of variables was performed using fractional factorial design (2IV7–2) to investigate the main parameters responsible for separating phenolic compounds. It was considered the initial and final % of bioethanol in the organic mobile phase, % acetic acid in aqueous mobile phase, flow rate, running time, type of column chemistry, and column temperature. The number of chromatographic bands was used as empiric response. The most important variables were selected to further optimization by Doehlert factorial design. The optimal condition was as follows: initial % of bioethanol=5%, final % of bioethanol=55%, column temperature= 51.8 °C, % acetic acid in H2O =0.1%, flow rate = 0.75 mL·min−1, time=30 min, and column chemical composition=Phenyl-Hexyl (X-Select). The optimized method allowed the separation of 24 chromatographic bands with signal/noise (S/N) higher than 100, a response at least 17% higher than observed in the screening step. The method allowed the separation and identification of the main compounds presented in red wines: gallic acid, caffeic acid, syringic acid, p-coumaric acid, resveratrol, kaempferol, catechin, and epicatechin.

The production of quality bee products, as well as bee survival itself, depends on the health conditions of the environment, but ironically, harmful solvents are often employed by scientists and traders to monitor the quality of these products. Many types of propolis have been recognized around the world, but specific biological activities can be expected for specific types of propolis. This work aimed to develop a new and green ultrahigh performance liquid chromatography method for the identification of green propolis type. The method was able to discern this type of propolis in a set of samples from seven countries as well as to cluster these samples by fingerprint similarity based on principal component analysis and partial least squares–discriminant analysis. This proved to be efficient, reproducible, and greener than methods previously reported in the literature for similar purposes and compatible with the cheap, largely available food grade ethanol produced from sugar cane