Steam distillation technique

The filter disc is transferred to a stopperred flask containing ethanol and propan-2-ol, and shaken to extract the water present which is then determined by gas-liquid chromatography the quantitity of water present is calculated from the ratio of the areas of the peaks for water (unknown) and ethanol (internal standard). The alkaloids are extracted from the filter disc using sulphuric acid and determined by a specially developed autoanalyser procedure based on the Koenig reaction this is shown schematically in Fig. 21. Since the procedure was developed specially for this application, results obtained from it were compared closely with those produced by the traditional manual method, a steam distillation technique, before it was adopted as a standard method. 

MAE was claimed as a most effective method for extraction for the selected analytes Determination GC-MS comparative tables with recoveries for the different methods are given MAE and steam distillation techniques were combined the use of isotope labeled internal standards for the MASD technique gave comparable results with the values obtained by other extraction methods and the certified values in the samples developed MASD technique was claimed better than simple MAE, conventional steam distillation, and Soxhlet extraction... 

Many of the organics that are normally extracted from aqueous samples using LLE t hniques can be extracted and concentrated more easily using steam distillation techniques. In some respects it can be thought of as a heated gas sparging technique. One apparatus particularly well-suited for the isolation of water insoluble neutral organics from aqueous samples is the steam distillation extractor (SDE)... 

The small voliunes of solvent normally used in steam distillation techniques facilitates solvent concentration and minimizes interferences due to solvent impurities and/or preservatives. Temperature stability of each analyte to be steam distilled must be demonstrated in the matrix. Extreme care must be exercised to be certain the species is neither formed nor destroyed during the several hour distillation/extrac-tion. 

Steam distillation A Bleidner apparatus can be used for the extraction of aromatic amines. In this system, a continuous steam distillation or continuous LLE is carried out and good recoveries are obtained (over 90%). The extraction solvent is isooctane and the extraction time is 2-3 h the technique is not laborious. Steam distillation extraction can be used quantitatively for different types of organic substances at microgram per liter to nanogram per liter levels. Good results can be obtained within 20 min. Steam distillation results in a cleaner extract and reduces the build-up of residue at the GC column. The small volumes of solvent normally used in steam distillation techniques facilitate solvent concentration and minimize interferences due to solvent impurities. 

Purpose. In this exercise you will extract oil of cinnamon from a native plant source, such as Cinnamomum zeylanicum, and then purify the principal flavor and odor component of the oil, cinnamaldehyde. The experiment demonstrates the importance of steam distillation techniques (at the semimicro level) [Pg.239]

Technique 2 Simple Distillation at the Semimicroscale Level (pp. 61-64) Technique 3 Steam Distillation Technique 4 Solvent Extraction... 

We will now examine, in Experiment [IIC], a third class of secondary metabolites the essential of/s.The majority of these materials are high-boiling liquids that can be extracted from plant material via steam distillation techniques. The value of codisfilling high-boOing substances was learned early in the days of alchemy. Because fhese oils often gave pleasant odors and flavors, they were considered to be the "essence"of the original plant material. Eventually, they became known as essential oils. 

In this experiment, a Hickman still is used to isolate the crude cyclohexanone product from the reaction mixture in an example of the steam distillation technique (see Prior Reading). The crude mixture collected in the collar of the still consists of cyclohexanone, water, and acetic acid. If any unreacted cyclohexanol is present in this mixture, it is removed in the subsequent chromatographic purification sequence using alumina. Gas chromatographic analysis may be used to determine the purity of the cyclohexanone product. 

The advantage of not requiring an elevated temperature holds also over traditional steam distillation techniques extracts obtained using suitable compressed and liquefied gases may be obtained at temperatures significantly lower than 100°C. 

The most popular device for fluoride analysis is the ion-selective electrode (see Electro analytical techniques). Analysis usiag the electrode is rapid and this is especially useful for dilute solutions and water analysis. Because the electrode responds only to free fluoride ion, care must be taken to convert complexed fluoride ions to free fluoride to obtain the total fluoride value (8). The fluoride electrode also can be used as an end poiat detector ia titration of fluoride usiag lanthanum nitrate [10099-59-9]. Often volumetric analysis by titration with thorium nitrate [13823-29-5] or lanthanum nitrate is the method of choice. The fluoride is preferably steam distilled from perchloric or sulfuric acid to prevent iaterference (9,10). Fusion with a sodium carbonate—sodium hydroxide mixture or sodium maybe required if the samples are covalent or iasoluble. 

The concern by consumers about cholesterol has stimulated the development of methods for its removal. Three principal approaches are in the pilot-plant stages use of enzymes, supercritical fluid extraction, and steam distillation. Using known techniques, it is not possible to remove all cholesterol from milk. Therefore, FDA guidelines identify cholesterol-free foods as containing less than 2 mg cholesterol per serving, and low cholesterol foods as containing from 2 to 20 mg (37). 

Essential Oils. Essential oils are produced by distillation of flowers, leaves, stems, wood, herbs, roots, etc. Distillations can be done directly or with steam. The technique used depends mosdy on the desired constituents of the starting material. Particular care must be taken in such operations so that undesired odors are not introduced as a result of pyrolytic reactions. This is a unique aspect of distillation processing in the flavor and fragrance industry. In some cases, essential oils are obtained by direct expression of certain fmits, particular of the citms family. These materials maybe used as such or as distillation fractions from them (see Oils, essential). 

Analytical Techniques. Sorbic acid and potassium sorbate are assayed titrimetricaHy (51). The quantitative analysis of sorbic acid in food or beverages, which may require solvent extraction or steam distillation (52,53), employs various techniques. The two classical methods are both spectrophotometric (54—56). In the ultraviolet method, the prepared sample is acidified and the sorbic acid is measured at 250 260 nm. In the colorimetric method, the sorbic acid in the prepared sample is oxidized and then reacts with thiobarbituric acid the complex is measured at - 530 nm. Chromatographic techniques are also used for the analysis of sorbic acid. High pressure Hquid chromatography with ultraviolet detection is used to separate and quantify sorbic acid from other ultraviolet-absorbing species (57—59). Sorbic acid in food extracts is deterrnined by gas chromatography with flame ionization detection (60—62). 

The C4 stream from steam crackers, unlike its counterpart from a refinery, contains about 45% butadiene by weight. Steam crackers that process significant amounts of Hquid feedstocks have satellite faciUties to recover butadiene from the stream. Conventional distillation techniques are not feasible because the relative volatihty of the chemicals in this stream is very close. Butadiene and butylenes are separated by extractive distillation using polar solvents. 

Shen, S. et al.. Comparison of solid-phase microextraction, supercritical fluid extraction, steam distillation, and solvent extraction techniques for analysis of volatile consituents in Fructus amomi, J. AOAC Int., 88, 418, 2005. 

Steam distillation is a process whereby organic liquids may be separated at temperatures sufficiently low to prevent their thermal decomposition or whereby azeotropes may be broken. Fats or perfume production are examples of applications of this technique. The vapour-liquid equilibria of the three-phase system is simplified by the usual assumption of complete immiscibility of the liquid phases and the validity of the Raoult and Dalton laws. Systems containing more than one volatile component are characterised by complex dynamics (e.g., boiling point is not constant). 

Applications Simultaneous steam distillation-solvent extraction has been in use for many years [163]. Steam distillation combined with continuous liquid extraction is an efficient technique for the removal and isolation of volatile compounds in various matrices (environmental,... 

Not all of the classical extraction processes are suitable for ultrasonic enhancement. For example, among the existing techniques used to obtain bio-active extracts from plant material (direct distillation, water steam distillation, organic solvent extraction, maceration, cold/hot fat extraction, etc.) [195] the water steam distillation is not amenable to ultrasonic enhancement. 

These can be the natural material itself one example would be pieces of vanilla pod or an extract, e.g. vanilla extract. Extracts can be prepared in several ways. One is to distil or to steam distil the material of interest. Another is to extract the raw material with a solvent, e.g. ethyl alcohol. Alternatively, some materials are extracted by coating the leaves of a plant with cocoa butter and allowing the material of interest to migrate into the cocoa butter. These techniques are also used in preparing perfumery ingredients, indeed materials like orange oil are used in both flavours and perfumes. 

PCBs in biological samples are usually extracted by a Soxhlet column and with a nonpolar solvent such as hexane. The sample is first mixed with sodium sulfate to remove moisture. The extraction of PCBs from sediments was tested with sonication, with two sonications interspersed at a 24-h quiescent interval, with steam distillation, or with Soxhlet extraction (Dunnivant and Elzerman 1988). Comparison of the recoveries of various PCB mixtures from dry and wet sediments by the four techniques and the extraction efficiency of four solvents showed that the best overall recoveries were obtained by Soxhlet extraction and the two sonication procedures. In comparisons of solvent systems of acetone, acetonitrile, acetone-hexane (1+1), and water-acetone-isooctane (5+1.5+1), recoveries of lower chlorinated congeners (dichloro- to tetrachloro-) were usually higher with acetonitrile and recoveries of higher chlorinated congeners (tetrachloro- to heptachloro-) extracted with acetone were superior (Dunnivant and Elzerman 1988). The completeness of extraction from a sample matrix does not seem to discriminate against specific isomers however, discrimination in the cleanup and fractionation process may occur and must be tested (Duinker et al. 1988b). 

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