Extraction separation analysis

Application of rotating coiled columns has become attractive for preparative-scale separations of various substances from different samples (natural products, food and environmental samples) due to advantages over traditional liquid-liquid extraction methods and other chromatographic techniques. The studies mainly made during the last fifteen years have shown that using rotating coiled columns is also promising for analytical chemistry, particularly for the extraction, separation and pre-concentration of substances to be determined (analytes) before their on-line or off-line analysis by different determination techniques. 

The choice of the method of analysis depends on the question to address. Spectrophotometry is sufficient for total curcuminoid content determination in a turmeric extract. Separation techniques coupled to mass spectrometry detection and MALDl-TOF are highly sensitive techniques that are more adapted to the identification of metabolites in biological fluids such as urine or plasma. ... 

In order to obtain reliable results, three steps are involved in the analysis sampling and sample preparation carotenoid extraction, separation, identification. 

Usually the first step is an extraction of the desired compounds from plant material. This extraction can be done by different solvents, e.g., methanol [85], n-hexane [86], petroleum ether or solvent mixtures such as methanol/chloroform [87]. The use of a second liquid-liquid extraction (LLE) with 0.1 M NaOH after extraction with a non-polar solvent like n-hexane makes a separate analysis of acidic cannabinoids possible, which can be found... 

Table 5.9 summarises the main features of FTIR spectroscopy as applied to extracts (separated or not). Since many additives have quite different absorbance profiles FTIR is an excellent tool for recognition. Qualitative identification is relatively straightforward for the different classes of additives. Library searching entails a sequential, point-by-point, statistical correlation analysis of the unknown spectrum with each of the spectra in the library. Fully automated analysis of... 

Scheme 7.3 Generalised supercritical fluid methods for extraction and analysis with and without separation of interfering components. After King [5], Reproduced from the Journal of Chromatographic Science, by permission of Preston Publications, a Division of Preston Industries, Inc.

Different fruits and vegetables vary significantly in their structural constituents, macronutrients (proteins, oils, and carbohydrates), and micronutrients such as flavonoid profiles. It is almost impossible to develop one optimal method for extraction, separation, and analysis for each and every different fruit or vegetable. However, because of the relatively similar chemistry and biochemistry of flavonoids, some general statements can be abstracted from the existing literature. Flavonoids of fruits and vegetables... 

Methods for PA Extraction, Separation, and Analysis 3.2.1 Extraction of Grape Seed PAs... 

The most economical procedure for a liquid-liquid extraction would be a single step extraction, since extraction procedures including several steps with the same or with different solvents are laborious and economically disadvantageous. Optimisation of extraction of more than one solute, which give different selective interactions (different response surfaces in the same mixture space), may require several extraction steps with different optimal extraction solvents or separate analysis of each analyte. However, procedures can be used, which select a composition of the extraction liquid that provides satisfactory partition coefficients or extraction yields for all solutes to be extracted. 

Initially, the use of HPLC in analysis of antioxidant properties with the DPPH" radical was restricted to chromatographic analysis of the radical content in solution. An assay was performed in which a solution of the radical was treated with the extract under analysis. The reaction ran in a reaction tube and the remainder of the radical after the reaction was analysed chroma-tographically. A comparison of the radical content in the blank sample and in the extract sample showed the amormt of radical that was quenched by antioxidants in the analysed sample [62, 63].However, themethoddidnotprovidemoreinformation than the colorimetricmethod. Much better results are obtained in a post-column on-line reaction in which substances separated on a chromatographic column react with a radical in a reaction coil. 

Effluent waters Measure the volume of water and remove 1 mL for GC-ECD analysis of chloroform. Adjust the pH of the remaining water to >11 and extract with 3 X 100 mL of CH2C12 adjust the pH to <2 and extract with 3 X 100 mL of CH2C12. Concentrate the CH2C12 extracts separately to a final volume of 1.0 mL spike with 5 /xg of n-pentadecane and n-undecane internal standard. Analyze the basic extract for all Group I compounds by capillary GC-FID. Analyze the acidic fraction for stearic acid after methylation and 2,4-dichlorophenol by capillary GC-FID. 

The adaptation of supercritical fluid extraction (SFE) in routine residue and metabolism analysis as well as other extraction/separation laboratories and applications has been slow. This is despite the demonstrated feasibility of using SFE for the removal of sulfonylureas, phenylmethylureas and their metabolites from soil and plant materials (1-2), as well as widespread demonstrated use of supercritical fluid extraction for other applications (3-6). The reason for this is simple. Although automated, SFE extraction apparatus typically only analyzes a single sample at a time. The technique could not compete effectively with the productivity of an experienced technician performing many sample extractions simultaneously. In essence, with a one vessel automated supercritical fluid extractor, operator attendance is high and throughput is about the same or even less than current conventional liquid-liquid and solid-liquid extraction techniques. 

Grate, J. W. and Egorov, O., Investigation and optimization of on-column redox reactions in the sorbent extraction separation of americium and plutonium using flow injection analysis, Anal. Chem., 70, 3920-3929, 1998. 

Aqueous samples are extracted with methylene chloride. A 1-L volume of sample is repeatedly extracted in a separatory funnel. The methylene chloride extract is exchanged to hexane during concentration to a volume of 1 mL. Nonaqueous samples, such as soils, sediments, sludges, fly ash, and tissues may be extracted by Soxhlett extraction or sonication. Methylene chloride, toluene, hexane, or a combination of these solvents may be used for extraction. Sludges containing 1% or more solids should be filtered. The aqueous filtrates and the solid residues are extracted separately. They are then combined prior to cleanup and analysis. 

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