Supercritical fluid extraction as a useful method for pesticides determination

Abstract

Despite attractive features (rapid extractions, small solvent volumes, non-toxicity of CO 2 , potential of selectivity depending on the fluid density, relatively clear and concentrated ex t ra c t s , p o s s i ble coupling with ch romatography and automation), the use of SFE in routine analytical ap p l i c ations is a rather slow process. Indeed, t h e major drawback of this recent technique is the large number of parameters to control and optimize, which results in time re q u i red for developing a new method. In add i t i o n , t h e extraction conditions are strongly dependent on the matrix to be extracted, so that parameters need to be adjusted for every new application. D e t e rm i n ation of pesticides remains a ch a l l e n ge fo r mainly three reasons: the wide variety of physicochemical properties and chemical structures of pesticides, the many possible matrices that should be investigated, and the trace c o n c e n t rations at wh i ch pesticides are usually pre s e n t . Recent papers reviewed environmental applications of SFE [1,2], especially with regards to the extraction of the main classes of pesticides [3][4][5]. As SFE perfo rmances are strongly dependent on the nature of the sample, this article will consider the matrices that have been submitted to SFE for pesticides determination. Principle of SFEA fluid is in its supercritical state when both its pressure and temperature are above their critical value (when only one c ritical value is at t a i n e d, the fluid is said subcri t i c a l ) . Supercritical fluids possess unique properties, intermediate between gas and liquids properties [6][7][8][9][10]. In particular, their high diffusivity allows for rapid extractions. In addition, the fluid density may be precisely adjusted, by a correct choice of both pressure and temperature.The key parts of an SFE system are the high-pressure pump wh i ch delive rs the fl u i d, and the re s t rictor wh i ch maintains the pressure inside the system. Extraction is performed inside a high-pressure cell (containing the sample), maintained at the correct temperature. The fluid may simply fill the cell (static mode), or continuously flow through the vessel (dynamic mode). The extracted solutes are entrained by the supercritical fluid flow out of the cell; their collection is usually achieved as the fluid is depressurized by passing through the restrictor. The collected solutes are further analyzed using gas or liquid chromatography. Also, a few recent studies report the use of enzyme immunoassay as a rapid screening process [5,11,12]. Alternatively, the SFE system may be coupled on-line with chromatographic systems, gas chromatography (GC), liquid chromatography (LC), or supercritical fluid chromatography (SFC), by means of an interface [5,8]. For example, the coupling of SFE and SFC e n abled the determ i n ation of thiolcarbamate herbicides (molinate and thiobencarb) from spiked soil samples (with organic content from 1.75 to 12.9%) [13]. Obviously, such a system seems very attractive when traces of pest...

Supercritical Fluid Chromatography: A Green Approach for Separation and Purification of Organic and Inorganic Analytes

“…Supercritical fluid extraction has been utilized to extract lipids from a variety of meats, including pork and beef Berg et al 1997). Supercritical fluid extraction can be tailored to the polarity of the solute of interest by changing the temperature and pressure of the extraction process for removal of pesticides residue from foods (Camel 1998). Estimation of these residual pesticides, herbicides and fungicides can be done by SFC (El-Saeid 2003).…”

Supercritical Fluids and the Food Industry

“…In addition, supercritical fluid extraction can be tailored to the solute of interest by changing the temperature and pressure of the extraction process. Supercritical fluid extraction can also be tailored for pesticides that contain more polar groups by the addition of polar modifiers to the CO 2 such as methanol (Camel 1998). The use of supercritical CO 2 for the extraction of pesticide residues has been reviewed extensively in other articles and so it will be only covered briefly in this article.…”

Supercritical extraction of contaminants from soils and sediments

“…Comprehensive presentations of various aspects on SCFs used in solute extraction from environmental matrices are provided in books [23][24][25][26][27], critical reviews [1][2][3][4][5][6][28][29][30][31][32][33][34][35], numerous articles, master and doctoral theses, research reports, etc. Although SCE has also applications as a treatment technology for inorganic contaminants, this review is focused on extraction of organic compounds.…”

“…Another review focused on understanding the SCE process in order to increase SCE recoveries and to use SCE in certification of complex environmental samples [34]. Largescale solvent extraction systems (including SCE) used to remove contaminants from soils, sediments, sludges, or wastewaters are also described [35].…”