Organic Solvent Extraction and Spectrophotometric Quantification of Total Phenolic Compounds in Soil

Abstract

Phenolic compounds are regarded as the most abundant plant metabolites that are known to decompose progressively into soils likened to other soil organic materials. Once assimilated into soils, they can control soil processes, including organic matter decomposition and nutrient cycling. Established that phenolic compounds can influence nutrients availability and soil quality, its crucial to investigate into soil phenolics through the application of the appropriate extraction technique and quantification of total phenolics in soils. This study therefore aimed at utilizing ethanol, hexane and diethyl ether organic solvents to extract and quantify total phenolic compounds in soil, sampled from vegetable growing area. Conventional organic solvent extraction method was employed to extract phenolics, while spectrophotometric technique was utilized to quantify total phenolic compounds. The highest extraction yield of 34.52% was achieved with ethanol followed by diethyl ether (28.23%) and then hexane (25.47%). Interestingly, hexane, which had the least extract yield rather recorded the highest phenolics concentration of 5.50 ± 0.02 mgGAE/g, with ethanol extract producing the least phenolics concentration of 2.04 ± 0.05 mgGAE/g. These results indicate that for an extraction efficiency and greater yield, the use of ethanol as an extraction solvent is preferred whereas extraction using hexane is suitable for total phenolics quantification. The findings of this study have provided a vital information regarding the influence of organic solvents on the extractability of phenolic compounds from soil.