Abstract
This work describes the construction and testing of a simple pressurized solvent extraction (PSE) system. A mixture of acetone:water (80:20), 80 oC and 103.5 bar, was used to extract two herbicides (Diuron and Bromacil) from a sample of polluted soil, followed by identification and quantification by high-performance liquid chromatography coupled with diode array detector (HPLC-DAD). The system was also used to extract soybean oil (70 oC and 69 bar) using pentane. The extracted oil was weighed and characterized through the fatty acid methyl ester analysis (myristic (< 0.3%), palmitic (16.3%), stearic (2.8%), oleic (24.5%), linoleic (46.3%), linolenic (9.6%), araquidic (0.3%), gadoleic (< 0.3%), and behenic (0.3%) acids) using high-resolution gas chromatography with flame ionization detection (HRGC-FID). PSE results were compared with those obtained using classical procedures: Soxhlet extraction for the soybean oil and solid-liquid extraction followed by solid-phase extraction (SLE-SPE) for the herbicides. The results showed: 21.25 ± 0.36% (m/m) of oil in the soybeans using the PSE system and 21.55 ± 0.65% (m/m) using the soxhlet extraction system; extraction efficiency (recovery) of herbicides Diuron and Bromacil of 88.7 ± 4.5% and 106.6 ± 8.1%, respectively, using the PSE system, and 96.8 ± 1.0% and 94.2 ± 3.9%, respectively, with the SLP-SPE system; limit of detection (LOD) and limit of quantification (LOQ) for Diuron of 0.012 mg kg-1 and 0.040 mg kg-1, respectively; LOD and LOQ for Bromacil of 0.025 mg kg-1 and 0.083 mg kg-1, respectively. The linearity used ranged from 0.04 to 1.50 mg L-1 for Diuron and from 0.08 to 1.50 mg L-1 for Bromacil. In conclusion, using the PSE system, due to high pressure and temperature, it is possible to make efficient, fast extractions with reduced solvent consumption in an inert atmosphere, which prevents sample and analyte decomposition.
Highlights
In recent years there has been an increasing interest in the control of harmful substances in the environment
The actual tendency in sample preparation techniques includes to the use of solid phase extraction (SPE),[4,5,6] supercritical fluid extraction (SFE),[7,8] accelerated solvent extraction (ASE),[9,10] microwave assisted extraction (MAE),[11,12,13] and solid phase micro extraction (SPME).[14,15,16]
The results indicate to be a good alternative for the preparation of several samples, as Supercritical Fluid Extraction (SFE), it subject of the high initial cost of the commercially available equipment.[17]
Summary
In recent years there has been an increasing interest in the control of harmful substances in the environment. Modern analytical techniques for sample preparation on the other hand minimize the costs and maximize the quality of the analytical results in a shorter time.[1,2,3]. The results indicate to be a good alternative for the preparation of several samples, as Supercritical Fluid Extraction (SFE), it subject of the high initial cost of the commercially available equipment.[17] The fundamental difference between the extractions using PSE and SFE is the physical state of the extractor fluid: PSE uses fluid in the liquid state and SFE uses fluid in the supercritical state
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