Solvent extraction carbon disulfide

This method can be applied when the adsorptive nature of the matrix may be problematic in extracting a representative sample. The fire debris is placed in a flask and extracted with an organic solvent. The volatile hydrocarbons that are miscible with the solvent are extracted from the debris. Commonly used solvents are carbon disulfide, dichloromethane, pentane, and hexane. The extract is filtered, evaporated to a small volume, and then analyzed. Sensitivity is similar to steam distillation however, interfering substances such as pyrolysis products are also extracted. 

The adsorbed analytes are extracted from the carbon filter by a small volume (10-50 xL) of an organic solvent, generally carbon disulfide, and analyzed without solvent concentration by GC. 

The heavy metal salts, ia contrast to the alkah metal salts, have lower melting points and are more soluble ia organic solvents, eg, methylene chloride, chloroform, tetrahydrofiiran, and benzene. They are slightly soluble ia water, alcohol, ahphatic hydrocarbons, and ethyl ether (18). Their thermal decompositions have been extensively studied by dta and tga (thermal gravimetric analysis) methods. They decompose to the metal sulfides and gaseous products, which are primarily carbonyl sulfide and carbon disulfide ia varying ratios. In some cases, the dialkyl xanthate forms. Solvent extraction studies of a large number of elements as their xanthate salts have been reported (19). 

Various types of detector tubes have been devised. The NIOSH standard number S-311 employs a tube filled with 420—840 p.m (20/40 mesh) activated charcoal. A known volume of air is passed through the tube by either a handheld or vacuum pump. Carbon disulfide is used as the desorbing solvent and the solution is then analyzed by gc using a flame-ionization detector (88). Other adsorbents such as siUca gel and desorbents such as acetone have been employed. Passive (diffuse samplers) have also been developed. Passive samplers are useful for determining the time-weighted average (TWA) concentration of benzene vapor (89). Passive dosimeters allow permeation or diffusion-controlled mass transport across a membrane or adsorbent bed, ie, activated charcoal. The activated charcoal is removed, extracted with solvent, and analyzed by gc. Passive dosimeters with instant readout capabiUty have also been devised (85). 

The extraction time has been observed to vary linearly with polymer density and decreases with smaller particle size [78,79]. The extraction time varies considerably for different solvents and additives. Small particle sizes are often essential to complete the extraction in reasonable times, and the solvents must be carefully selected to swell the polymer to dissolve the additives quantitatively. By powdering PP to 50 mesh size, 98 % extraction of BHT can be achieved by shaking at room temperature for 30 min with carbon disulfide. With isooctane the same recovery requires 125 min Santonox is extractable quantitatively with iso-octane only after 2000mm. The choice of solvent significantly influences the duration of the extraction. For example talc filled PP can be extracted in 72 h with chloroform, but needs only 24 h with THF [80]. pH plays a role in extracting weakly acidic and basic organic solutes, but is rarely addressed explicitly as a parameter. 

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. 

Air (particulates and gas) Sequential collection on Teflon filters and charcoal tubes solvent extraction with hexane (filters) and carbon disulfide (charcoal tubes) GC/MS Not specified Not specified Dannecker et al. 1990... 

Organic compounds are extracted from the charcoal with a small volume of a suitable solvent such as carbon disulfide or dichloromethane, then collected and injected into a capillary gas chromatograph or a capillary gas chromatograph coupled with a mass spectrometer. 

When solvent extraction was performed, the procedure used by Dutka et al. [406] was followed with a slight modification 2 ml of concentrated hydrochloric acid and 5 ml of 20% (w/v) sodium chloride were added to each litre of water sample. The sample was extracted with vigorous mixing three times with 100 ml each of hexane for 30 min. The combined extract was washed with two 50 ml portions of acetonitrile (saturated with hexane) followed by two 50 ml portions of 70% ethanol. The hexane was then brought to dryness on a rotary evaporator under reduced pressure. The sample was re-dissolved in 100-200 pi of carbon disulfide, and 1-5 pi of the solution was used for gas chromatographic analysis. 

The carbon disulfide is decanted, and 200-300 ml. of water is added to the contents of the flask. Initially the mixture reacts slowly, but after some time the reaction becomes so vigorous that it is necessary to pour off the water (Notes 1 and 2). The addition of water, followed by its removal when the reaction becomes very vigorous, is repeated until decomposition is complete. The combined aqueous solutions are extracted several times with chloroform, and the combined extracts are dried over anhydrous sodium sulfate. Distillation of the solvent gives a dark brown liquid residue which is distilled under reduced pressure to give 310.3 g. (89%) of the thioamide as a yellow liquid, b.p. 133-135° (12 mm.) (Note 3). 

Reaction of carbon with sulfur dioxide was observed by Fischer and Prauschke (131). In my laboratory it was recently found that sulfur is bound by heat-treated carbon blacks and by graphitized carbon black on treatment with hydrogen sulfide, carbon disulfide, or sulfur dioxide at low temperatures, even at room temperature. The sulfur content cannot be eliminated by outgassing at 100° or by prolonged extraction with various solvents. 

FIGURE 3 2 Solvent extraction efficiencies (EF) as functions of dielectric constants (D), solubility parameters (6), and polarity parameters (P and E -). Solvents studied silicon tetrachloride, carbon disulfide, n pentane. Freon 113, cyclopentane, n-hexane, carbon tetradiloride, diethylether, cyclohexane, isooctane, benzene (reference, EF 100), toluene, trichloroethylene, diethylamine, chloroform, triethylamine, methylene, chloride, tetra-hydrofuran, l,4 dioxane, pyridine, 2 propanol, acetone, ethanol, methanol, dimethyl sulfoxide, and water. Reprinted with permission from Grosjean. ... 

A condenser is attached to one of the side necks, and the carbon disulfide is distilled without removing the flask from the steam bath. After the removal of the solvent (Note 4), the reaction mixture is allowed to cool somewhat (Note 5) but while it is still warm, it is poured slowly with stirring over cracked ice to which hydrochloric acid has been added. In this way only a small amount of the aluminium chloride addition product remains in the flask. This is decomposed with ice and hydrochloric acid and added to the main product. The volume is now about 5 1. Each 2-1. portion is extracted twice with 300-cc. 

Benzobis(trithiolo)pentathiepin 106 was isolated as a by-product from reaction of the thiolates with sulfur dichloride by extraction with carbon disulfide and removal of the solvent (Equation 19) <1995T2533>. 

The NIOSH methods, in general, are based on adsorption of compounds in the air over a suitable adsorbent, desorption of the adsorbed analytes into a desorbing solvent, and, subsequently, their determination by GC using a suitable detector. A known volume of air is drawn through a cartridge containing coconut shell charcoal. The adsorbed compounds are desorbed into carbon disulfide, propanol, benzene, toluene, hexane, or methylene chloride. An aliquot of the solvent extract is then injected onto the GC column. FID is the most commonly used detector. Other detectors, such as ECD, ELCD, or PID have been used, however, in the method development of certain compounds. NIOSH method numbers and the analytical techniques are presented in Table 2.9.3. 

Separation of DEHP from environmental samples is usually by extraction with an organic solvent such as acetonitrile, chloroform, ethyl acetate, hexane, or methylene chloride. Air samples are drawn through a solid sorbent material (e.g., charcoal or XAD-2 resin) and desorbed with carbon disulfide (NIOSH 1985b) or ether/hexane (Rudel et al. 2001). A purge and trap method might be used for separation of DEHP from the fat in foods (van Lierop and van Veen 1988). Detector options are identical to those mentioned above (Section 7.1). Detection limits for these methods are generally in the ppb range. 

Uses Benzene is a clear, colorless, sweet-smelling liquid. Commercial benzene often consists of toluene, xylene, phenol, and traces of carbon disulfide. Benzene in large volumes is produced by fractionation distillation from crude oil, solvent extraction, and as a by-product of coke-oven processing. Benzene is found in coal tar distillates, petroleum naphtha, and gasoline.1... 

The active charcoal material is placed in a glass vial. The extraction solvent is added (twice the volume of the charcoal) and the mixture is sonicated for 3 min. Suitable solvents are acetone, dichloromethane, carbon disulfide, and deuterated... 

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