Methodologies for the Extraction of Phenolic Compounds from Environmental Samples: New Approaches

Cristina Mahugo Santana,José Juan Santana Rodríguez,Zoraida Sosa Ferrera,M Esther Torres Padrón

doi:10.3390/molecules14010298

Cristina Mahugo Santana, José Juan Santana Rodríguez + Show 2 more

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https://doi.org/10.3390/molecules14010298

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Abstract

Phenolic derivatives are among the most important contaminants present in the environment. These compounds are used in several industrial processes to manufacture chemicals such as pesticides, explosives, drugs and dyes. They also are used in the bleaching process of paper manufacturing. Apart from these sources, phenolic compounds have substantial applications in agriculture as herbicides, insecticides and fungicides. However, phenolic compounds are not only generated by human activity, but they are also formed naturally, e.g., during the decomposition of leaves or wood. As a result of these applications, they are found in soils and sediments and this often leads to wastewater and ground water contamination. Owing to their high toxicity and persistence in the environment, both, the US Environmental Protection Agency (EPA) and the European Union have included some of them in their lists of priority pollutants. Current standard methods of phenolic compounds analysis in water samples are based on liquid–liquid extraction (LLE) while Soxhlet extraction is the most used technique for isolating phenols from solid matrices. However, these techniques require extensive cleanup procedures that are time-intensive and involve expensive and hazardous organic solvents, which are undesirable for health and disposal reasons. In the last years, the use of news methodologies such as solid-phase extraction (SPE) and solid-phase microextraction (SPME) have increased for the extraction of phenolic compounds from liquid samples. In the case of solid samples, microwave assisted extraction (MAE) is demonstrated to be an efficient technique for the extraction of these compounds. In this work we review the developed methods in the extraction and determination of phenolic derivatives in different types of environmental matrices such as water, sediments and soils. Moreover, we present the new approach in the use of micellar media coupled with SPME process for the extraction of phenolic compounds. The advantages of micellar media over conventional extractants are reduction of organic solvent, low cost, easy handling and shorter time procedures.

Highlights

Phenolic compounds are present in the environment as a result of their uses and the processes in which they are implicated
The use of pentachlorophenol is prohibited in most countries, it is still widely found in the wood of pallets, containers, crates and in cardboard, paper, etc
Current official analytical methods for phenolic compounds extraction are liquidliquid extraction (LLE) (US Environmental Protection Agency (EPA) Methods 604, 605, 8041) [18,19,20] for liquid samples, and Soxhlet extraction, for solid samples [21]. These methods require expensive and hazardous organic solvents, which are undesirable for health and disposal reasons, and they involve a long time per analysis

Summary

Introduction

Phenolic compounds are present in the environment as a result of their uses and the processes in which they are implicated. The high polarity of free phenols hinders their correct chromatographic resolution because they produce broad, tailed peaks; this limitation can be circumvented by derivatising free phenols to less polar compounds, such as acetylated derivatives They are commonly derivatised either before or after extraction, or with an on column reagent in the GC injector port. Current official analytical methods for phenolic compounds extraction are liquidliquid extraction (LLE) (US EPA Methods 604, 605, 8041) [18,19,20] for liquid samples, and Soxhlet extraction, for solid samples [21] These methods require expensive and hazardous organic solvents, which are undesirable for health and disposal reasons, and they involve a long time per analysis. We present the main advantages and limitations of more conventional methods, those which use organic solvents, and highlight recent developments and trends in this field with new methodologies, namely green methods or environmentally friendly methods, which try to eliminate or reduce, at least, the use of these solvents

Extraction methods using organic solvents

Findings

Conclusions