Shake-flask extraction

Conventional methods of polymer extraction use large quantities of solvents as in shake-flask extraction or a Soxhlet extraction apparatus. For all classical extraction methods, solvent selectivity, in general, is low, i.e. solvents with high capacity tend to have low selectivity. In reflux extractions, which are still quite popular in polymer applications, the polymer is refluxed with a hot solvent, which disperses it to provide a solvent phase containing additives. In these conditions solvents are at their atmospheric boiling point. These methods are lengthy and labour intensive. Fractional extraction is based on solvents with increasing solvent power (cf. also [81]). 

Principles and Characteristics Conventional LSE in the form of shake-flask extraction is carried out... 

Mixing, wrist shaking, or tumbling combinations offer a simple, effective, but time-consuming and not highly reproducible method of extraction. Sample-to-solvent ratios are similar to Soxhlet ratios. Although sample manipulation is reduced, this technique requires nearly as much time as the Soxhlet method. Shake-flask extraction is low cost. 

Applications Shake-flask extraction nowadays finds only limited application in polymer/additive analysis. Carlson et al. [108] used this technique to extract antioxidants from rubber vulcanisates for identification purposes (NMR, IR, MS). Wrist-action shaking at room temperature was also used as the sample preparation step for the UV and IR determination of Ionol CP, Santonox R and oleamide extracted from pelletised polyethylene using different solvents [78]. BHT could be extracted in 98 % yield from powdered PP by shaking at room temperature for 30 min with carbon disulfide. 

Freitag and John [96] studied rapid separation of stabilisers from plastics. Fairly quantitative extraction (>90% of the expected content) of stabilisers from a powdered polymer was achieved by MAE within 3 to 6 min, as compared to 16 h of Soxhlet extraction for the same recovery. MAE and Soxhlet extraction have also been compared in the analysis of cyclic trimer in PET [113]. On the other hand, Ganzler et al. [128] compared the extraction yields for various types of compounds from nonpolymeric matrices for microwave irradiation with those obtained by the traditional Soxhlet or shake-flask extraction methods. Microwave extraction was more effective than the conventional methods, in particular in the case of polar compounds. As expected, the efficiency of the former is high especially when the extraction solvents contain water. With the high dipole moment of water, microwave heating is more... 

Pesticides such as atrazine and simazine have also been extracted from honey with the aid of an ultrasonic bath. In addition to the type of extractant, variables such as the extractant volume, sonication time and number of extraction cycles were optimized, the temperature and the height of the transmitting liquid in the bath being kept constant. A comparison of the ensuing method with its shake-flask extraction counterpart showed the former to be faster and more efficient, and provide relatively lower standard deviations [9]. 

To be able to carry out shake-flask extraction in a safe and controlled manner. 

Conventional liquid-solid extraction, in the form of shake-flask extraction, is carried out by placing a soil sample into a suitable glass container, adding a suitable organic solvent, and then agitating or shaking. 

Figure 7.5 Typical procedure used for the shake-flask extraction of solids.

Example 7.2 Shake-Flask Extraction of Phenols from Contaminated Soil... 

Figure 7.6 Results obtained for the shake-flask extraction of various phenols from contaminated soil and Celite A, phenol B, 3-cresol C, 4-ethylphenol D, 1-naphthol , Celite . soil [2] (cf. DQ 7.4).

It can be noted that, in most cases, lower recoveries are obtained when shake-flask extraction is used to remove phenols from soil when compared to Celite (an inert siliceous matrix). This effect is most pronounced with 1-naphthol. 

Shake-flask extraction Method of extracting analytes from matrices using agitation or shaking in the presence of a solvent. 

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. 

Principles and Characteristics Normally, analysis of solid materials prior to chromatographic separation and detection requires some form of extraction with organic solvents, either by heating (Soxhlet, Soxtec, etc), agitation (sonication or shake-flask extraction) of the organic solvent-solid mixture, or by more recently introduced techniques (MAE, SEE, ASE ). In particular the latter approaches are costly in terms of equipment. It has been shown that solid-phase microextraction (SPME) can also be utilised for direct analysis of solids [991]. 

As described in U.S. Patent 2,931,798, Streptomyces kanamyceticus (K2-J) was first cultured in shake flasks in the following media (a) 0.75% meat extract, 0.75% peptone,... 

A 20-g sample of air-dried soil is extracted with 100 mL of ethyl acetate in a flask shaker for 45 min. After shaking, the extract is decanted and separated. The soil is re-extracted with 100 mL of ethyl acetate for 45 min. The combined soil extracts are filtered through a Whatman No 1 filter paper and the filter cake is washed with an additional 20 mL of ethyl acetate. The extracts are evaporated nearly to dryness, under vacuum, using a rotary evaporator. The residue is dissolved in an appropriate volume before GC analysis. ... 

Transfer an aliquot of the extract (around 250 mL) into a 500-mL separatory funnel, add 20 g of the sodium chloride and shake vigorously. Extract the mixture with 100 mL of dichloromethane. Dry the extracts with anhydrous sodium sulfate, filter through a cotton-wool plug and measure the volume. Transfer an aliquot of the extract (around 260 mL) into a 500-mL round-bottom flask and concentrate to around 5 mL with a rotary evaporator. Transfer the sample to a centrifuge tube with 5 mL of ethyl acetate and partition. Repeat the partitioning twice more, combine the ethyl acetate fractions and concentrate to dryness with a rotary evaporator. 

Solvent degassing (LC) 553 Solvent demixing (TLC) 660 Solvent effects, splitless injection (GC) 250 Solvent extraction 753 applications 766 hoBogenizer 761 i plitgers 756 micTMethods 764 microwave 761 optimization 753 shake flask 761 solvent reduction 763 Soxhlet 762 Solvent (LC)... 

Washing/soakinga Shake-flask extraction12 In-vial LSEa Reflux extraction Soxhlet/Soxtec /Soxtherm extraction... 

In liquid-solid extraction (LSE) the analyte is extracted from the solid by a liquid, which is separated by filtration. Numerous extraction processes, representing various types and levels of energy, have been described steam distillation, simultaneous steam distillation-solvent extraction (SDE), passive hot solvent extraction, forced-flow leaching, (automated) Soxh-let extraction, shake-flask method, mechanically agitated reflux extraction, ultrasound-assisted extraction, y -ray-assisted extraction, microwave-assisted extraction (MAE), microwave-enhanced extraction (Soxwave ), microwave-assisted process (MAP ), gas-phase MAE, enhanced fluidity extraction, hot (subcritical) water extraction, supercritical fluid extraction (SFE), supercritical assisted liquid extraction, pressurised hot water extraction, enhanced solvent extraction (ESE ), solu-tion/precipitation, etc. The most successful systems are described in Sections 3.3.3-3.4.6. Other, less frequently... 

In the framework of the phthalate controversy Wilkinson and Lamb [109] used various in vitro methods in which known amounts of soft PVC materials were shaken, stirred, impacted, or otherwise mechanically agitated in some type of simulated saliva under controlled conditions (T, f), and the saliva extracted into hexane for analysis. Shaking-flask (liquid-liquid) extraction was also used for the solvent extraction of nonionic surfactants of the general type R0(CH2CH20) H (where R... 

S, Soxhlet S , Soxtec R, reflux SF, shake-flask US, ultrasonics SFE, supercritical fluid extraction MAE, microwave-assisted extraction PFE, pressurised fluid extraction (ASE , ESE ) D/P, dissolution/precipitation. 

Mineral Oil Hydraulic Fluids. Methods are available for analysis of the hydrocarbon components of mineral oil hydraulic fluids (predominantly straight and branched chain alkanes) in environmental samples. Some of these methods are summarized in Table 6-3. In general, water and sediment samples are extracted with a suitable solvent in a Soxhlet extractor (for solid samples) or in separatory funnel or shake flask (for liquid samples) (Bates et al. 1984 Peterman et al. 1980). The extract is cleaned up on silica gel or Florisil columns using a nonpolar solvent to elute the nonpolar alkanes. Analysis is usually performed by GC/MS (Bates et al. 1984 Kawamura and Kaplan 1983 Peterman et al. 1980). Method performance has not been reported, although 82% recovery of aliphatic hydrocarbons was reported for rainwater (Kawamura and Kaplan 1983). 

C, shake flask-solid extraction-GC/FID, measured range 29.9-183°C, Marche et al. 2003)... 

C, shake flask-solid phase extraction-GC, measured range 38.35-280°C, Heidman et al. 1985)... 

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