Pressurized fluid extraction samples

More elaborate sample preparation is often needed for complex sample matrices, e.g., lotions and creams. Many newer SP technologies such as solid-phase extraction (SPE), supercritical fluid extraction (SFE), pressurized fluid extraction, accelerated solvent extraction (ASE), and robotics are frequently utilized (see Ref. [2]). Dosage forms such as suppositories, lotions, or creams containing a preponderance of hydrophobic matrices might require more elaborate SP and sample cleanup, such as SPE or liquid-liquid extraction. 

ASE—also referred to as pressurized fluid extraction (PFE)—offers an order of magnitude of additional reductions in solvent use with faster sample processing time, and with the potential of automated, unattended extraction of multiple samples. Briefly, with ASE a solid sample is enclosed in a cell containing an extraction solvent after the cell has been sealed, the sample is permeated by... 

Accelerated solvent extraction (ASE) is also known as pressurized fluid extraction (PFE) or pressurized liquid extraction (PLE). It uses conventional solvents at elevated temperatures (100 to 180°C) and pressures (1500 to 2000 psi) to enhance the extraction of organic analytes from solids. ASE was introduced by Dionex Corp. (Sunnyvale, CA) in 1995. It evolved as a consequence of many years of research on SFE [45], SFE is matrix dependent and often requires the addition of organic modifiers. ASE was developed to overcome these limitations. It was expected that conventional solvents would be less efficient than supercritical fluids, which have higher diffusion coefficients and lower viscosity. However, the results turned out to be quite the opposite. In many cases, extraction was faster and more complete with organic solvents at elevated temperature and pressure than with SFE. Extensive research has been done on the extraction of a variety of samples with ASE. ASE was approved by EPA as a standard method in 1996. 

Yandenburg et al. [92] compared extraction of additive Irganox 1010 from freeze-ground polypropylene polymer by pressurized fluid extraction (PFE) and MAE with reflux, ultrasonic, shake-flask, and Soxhlet extraction. PFE and MAE were faster than any conventional method with comparable extraction efficiency. The times to reach 90% recovery by PFE using propan-2-ol at 150°C and acetone at 140°C were 5 and 6 minutes, respectively. Reflux with chloroform was found to be the fastest method performed under atmospheric pressure with 90% recovery in 24 minutes. Reflux with cyclohexane propan-2-ol (1 1) required 38 minutes. Ultrasonic, shake-flask, and Soxhlet extraction required about 80 minutes (90%) extraction). The total sample preparation time for PFE was 15 minutes, MAE 28 minutes, and reflux with chloroform was 45 minutes. 

A variety of solvent extraction techniques have been used to extract antioxidants from food matrices. The most commonly used is maceration or homogenization of the sample with an extraction solvent however, alternative procedures have been developed including pressurized fluid extraction (PFE), ultrasound-assisted extraction (UAE), microwave-assisted extraction (MAE), and matrix solid-phase dispersion (MSPD), among others. The principles of each extraction technique will be briefly discussed. 

Pressurized fluid extraction is another technology that applies high pressure extraction solution in the sample matrix to perform extraction. The solution is water or water mixed with different polar solvents, and its extraction pressure is lower than 1 atm. The extraction solvent and sample can be heated to 200 °C to weaken the sample matrix and allow solvent to penetrate. Compared to traditional extraction methods, pressurized fluid extraction has short extraction time and requires less solvent. As with other extraction methods, extraction temperature and pressure and solvent composition are very critical to the phenolic acid extraction yield (Palma et al., 2001, 2002 Mukhopadhyay et ah, 2006). 

Alternatively, one could use a Soxhlet or similar apparatus to extract the sample. Other methods to prepare a sample for analysis through extraction include supercritical fluid extraction (SFE), pressurized fluid extraction, and microwave-assisted solvent extraction. 

The accelerated solvent extraction (ASE) system introduced by Dionex uses standard solvents at elevated temperatures and pressures to increase extraction efficiency. Samples are placed in stainless-steel extraction vessels that are loaded into the ASE that has been programmed for the extraction protocol. The instrument allows for the unattended extraction of 24 samples. The initial units allowed for solvent blending by premixing solvents before they were placed into the ASE. Recent modifications allow solvent blending to be accomplished in-line. There has been some controversy about the use of the name ASE because it points to instrumentation from one company and other companies have introduced competing products. It has been proposed that the ASE technology be more correctly referred to as pressurized fluid extraction because ASE denotes a commercial device. 

Since pressurized fluid extraction (PFE), also known as accelerated solvent extraction (ASE ), is a relatively new technique, the commercial availability of PFE instruments is limited. A commercial PFE system ( ASE 200 ) currently available is a fully automated sequential extractor developed by the Dionex Corporation, USA. This mainly consists of a solvent-supply system, extraction cell, oven, collection system and purge system, all of which are under computer control. A schematic diagram of a PFE system is shown in Figure 7.15. This system (ASE 200) can operate with up to 24 sample-containing extraction vessels and up to 26 collection vials, plus an additional four vial positions for rinse/waste collection. 

The focus in Chapters 7 and 8 is on the specific sample preparation approaches available for the extraction of organic compounds from environmental matrices, principally soil and water. Chapter 7 is concerned with the role of Soxhlet, ultrasonic and shake-flask extraction on the removal of organic compounds from solid (soil) matrices. These techniques are contrasted with newer developments in sample preparation for organic compound extraction, namely supercritical fluid extraction, microwave-assisted extraction and pressurized fluid extraction. Chapter 8 is arranged in a similar manner. Initially, details are provided on the use of solvent extraction for organic compounds removal from aqueous samples. This is followed by descriptions of the newer approaches, namely solid-phase extraction and solid-phase microextraction. 

Soxhlet extraction remains the most popular means of extracting CPs from solid samples [11,18, 19, 23, 25, 28]. This classical technique is robust, easy to use, and inexpensive and has been applied successfully to the analysis of other organohalo-genated compounds. Drawbacks to the technique are lengthy extraction times (typically greater than 6 h) and the use of large volumes of solvents. Newer techniques like pressurized fluid extraction (PLE, or accelerated solvent extraction (ASE)) and microwave assisted extraction (MAE) have been shown to mitigate these two factors. 

Extraction of herbicides from solid matrixes has frequently been done by Soxhlet extraction, which required large volumes of solvent and was a time consuming process. Therefore, new extraction techniques have been developed and applied for the past ten years. Herbicides and their main metabolites can be extracted from sohd samples by these new methods such as, SFE, subcritical water extraction (SWE), microwave-assisted extraction (MAE), or pressurized fluid extraction (PFE). From a general point of view. Camel evaluated potentials and pitfalls of SEE, MAE, and PFE. ... 

Bidleman TF (1988) Atmospheric process wet and dry deposition of organic compounds are controlled by their vapor-particle partitioning. Environ Sci Technol 22 361-367 Bjorklund E, Bowadt S, Nilsson T, Mathiasson L (1999) Pressurized fluid extraction of polychlorinated biphenyls in solid environmental samples. J Chromatogr A 836 285-293 Braun T, Navratil JD, Farag AB (1986) Polyurethane foam sorbents in separation science. CRC Press, Boca Raton... 

Depending on the way the sample and extractant are brought into contact, pressurized fluid extraction (PFE) can be implemented in three different operational modes, static, dynamic, and static-dynamic. 

Pressure fluid extraction (PFE) PFE mainly consists of a static or dynamic pressure and temperature assisted liquid-solid extraction. Phenyl ureas from soils and sulfonyl ureas from maize samples were extracted under pressure with methanol at 50°C, using a dynamic setup at 1 ml min and using a total extractant volume of 25 ml. 2,4-D, 2,4,5-T, dicamba, trichlorpyr, and bentazone have been in situ derivati-zed during the PFE procedure. The variables temperature, pressure, static extraction time, and derivatization reagent amount should be subjected to optimization in order to increase recoveries. Addition of sodium EDTA in the extraction chamber strongly increases 2,4-D recovery. 

Given the increasing complexity of samples, it becomes imperative that the preparation techniques are highly reliable. This necessitates minimal effort and duration combined with enhanced accuracy and precision. Supercritical fluid extraction (SEE), pressurized fluid extraction (PEE), and assisted solvent extraction (ASE) procedures have been developed as reliable alternatives to traditional methods of sample preparation. 

Pressurized liquid extraction (PLE) is also known as pressurized solvent extraction (PSE), enhanced solvent extraction (ESE), pressurized fluid extraction (PEE), or accelerated solvent extraction (ASE ) in the literature. PLE is considered an environmentally friendly extraction technique because it requires only small volumes of solvents. PLE was primarily used for the extraction of environmental samples, such as soils and sediments. Elevated temperatures (usually between 50 and 200 °C) and pressures (between 10 and 15 MPa) are used in closed vessels, which allow extractions to be completed in a very short time. High pressure allows the solvent to remain in its liquid state even at temperatures above its boiling point, and forces it into the matrix pores. High temperatures decrease the solvent viscosity and increase metabolite solubilization, the diffusion rate, and mass transfer kinetics, thus facilitating desorption of the analytes from the plant material. Most PLE applications reported in the literature employ the same organic solvents as those commonly used in conventional solid-liquid extraction techniques. When water is used as the extraction solvent, the technique is referred to as pressurized hot water extraction (PHWE). Extractions are carried out in stainless steel extraction cells of various volumes (typically 1-250 mL). One extraction cycle is generally applied for 5-20 min at temperatures ranging from 50 to 140 °C in the vast majority of applications. 

Soxhlet extraction is the most commonly used technique to quantitatively remove PCDDs and PCDFs from solid environmental matrices (such as sediments, fly ash, particulate matter) and solid sorbents employed in air or water sampling. A Dean-Stark apparatus is often used in combination with the Soxhlet extractor to remove traces of water [13]. Besides the classical Soxhlet apparatus, other innovative techniques have been developed for the extraction of organic substances from solid matrices. Among these techniques, the pressurized fluid extraction (PEE) found wide acceptance in the scientific community. 

This study focuses on the development of a quick method for the extraction and detection of fipronil residues and its main three metabolites in Hawaiian soil (Helemano series) and cotton gauze swipe samples. Pressurized fluid extraction was used for its ease of use and automated state, its reduction in organic solvent consumption, and time saving interests. Gas chromatography-mass spectrometry (GC-MS) in selected ion monitoring mode was enq )loyed for the detection and quantiflcation of the extracts. The extraction method was optimized for the Hawaiian soil for the simultaneous extraction of the four confounds, and was then applied to soil and cotton gauze sanq)les collected from Maui, Hawaii, after a residential spray of fipronil. 

Method 3545 uses pressurized fluid extraction at 100°C and a pressure up to 2000 psi to remove organophilic analyte species from dried solid samples including soils, clays, sediments, sludges, and waste soHds. Used for the extraction of semivolatile organic compoimds, organophosphorus pesticides, organochlorine pesticides, chlorinated herbicides, and PCBs, it requires less solvent and takes less time than the Soxhlet extraction described above. 

Dialysis (passive sampling with SPMDs) Microwave-assisted extraction Pressurized-fluid extraction Supercritical-fluid extraction... 

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