Solvent extraction with acetonitrile

Accurate quantitation of anthracyclins in fermentation broths is important to facilitate determination of the ideal harvest time. Extraction of anthracyclins from these broths uses an initial acid treatment at pH 1.5 (Alemanni et al., 1982) and subsequent filtration or solvent extraction with acetonitrile-water (80 20). Samples can then be filtered for direct injection onto tm HPLC column. This procedure has been used to examine ten anthracyclins produced in a fermentation broth. HPLC was carried out on a Cjg reversed phase support in combination with an acetonitrile-aqueous phosphate buffer mobile phase (Fig. 11.9.8). 

Solvent extraction with acetonitrile, methanol, or ethanol Filtration, concentration... 

In residue analysis in air, a known amount of air is passed through a sampling cartridge. The trapped benfuracarb is extracted with acetonitrile. The solvent extract is removed by rotary evaporation, the residue is dissolved in acetonitrile and the solution is subjected to HPLC analysis. 

Finally, the Boc group was removed by treatment with aqueous HC1. Free amine 3 was isolated by extraction with acetonitrile in the presence of NaCl after basifica-tion with NaOH. Free amine 3 crystallized upon standing at room temperature, as shown in Scheme 2.13. It was found that when 3 was left standing in CH2C12 for long period [22], which was the solvent for the next step, it reacted with solvent to form dimer 52, together with formation of the HC1 salt of 3. 

Eight BDZs among the most frequently encountered in forensic toxicology (clonazepam, desal-kylflurazepam, diazepam, flunitrazepam, lorazepam, midazolam, nordiazepam and oxazepam) were determined in whole blood after solvent extraction with butyl chloride and fast isocratic separation using a C18 (100 x 4.6 mm x 5 (tm) column [61]. The mobile phase was composed of phosphate buffer (35mM, pH 2.1) and acetonitrile (70 30, v/v) and the flow rate was 2mL/min. Within less than 4 min of analysis time, the analytes could be successfully determined starting from therapeutic concentrations. Using HPLC coupled with APCI-MS-MS, Rivera et al. [62] set up a method for the detection of 18 BDZ and metabolites after butyl chloride extraction at alkaline pH in 0.5mL... 

Homogenization of sample and extraction with acetonitrile, filtration, addition of salt and solvent evaporation. Redissolution of residue in acetone for analysis. 

The resin was then purified by sequential solvent extractions with methanol, acetonitrile, and ethyl ether in a Soxhlet extractor for 8 h per solvent. 

The macroreticular resin, XAD-2 is obtained from Rohm and Haas (Philadelphia, Pa. U.S.A.). The fines are removed by slurrying in methanol and decanting. The remaining resin beads, predominantly 20-60 mesh, are purified by sequential solvent extractions with methanol, acetonitrile, and diethyl ether in a Soxhlet extractor for 8 hr per solvent. The purified resins are stored in glass-stoppered bottles under methanol to maintain their high purity. In some cases the resins as received from the supplier are ground to smaller... 

The mixture of sodium phenyl sulfinate (6.566 g, 40 mmol) and neutral chromatographic alumina (20 g) was evaporated with a rotary evaporator under vacuum. The solid was dried 2 h at 110°C under vacuum. The alkyl halide (5 mmol) was absorbed onto sodium phenyl sulifinate on alumina (6.6 g, 1.52 mmol of sodium phenyl sulfinate). The mixture was irradiated by microwave (160 W, 5 min). After cooling at room temperature the mixture was extracted with acetonitrile. The product was recrystallized in ethanol after evaporation of solvent. 

Aqueous samples are extracted with methylene chloride by liquid-liquid extraction in a separatory funnel or a liquid-liquid extractor. The extract is concentrated to 1 mL for GC analysis. If HPLC analysis were to be performed, methylene chloride should be exchanged to acetonitrile by evaporating the solvent extract with a few mL of acetonitrile and adjusting the final volume to 1 mL. 

Solid samples extracted with acetonitrile extract diluted with water the resulting solution mixed with methylene chloride-petroleum ether mixture (20 80) (A) and shaken analyte partitions into (A) solvent layer (A) repeatedly washed with saturated NaCl solution the extract then cleaned up on a florisil column (first eluted with 200 ml solution A and then with a mixture of methylene chloride 50% and 1.5% acetonitrile in petroleum ether eluant concentrated and diluted to desired volume with petroleum ether analyzed by GC-ECD (Pomer-antz et al., 1970). 

Powdered tablets of chlorthalidone and reserpine are extracted with acetonitrile/water (9 l), centrifuged and the supernatant layer is injected to HPLC using a column of Pellamidon at 35°c and the solvent isopropanol/acetic acid/water/hexane (60 3 1 36) as the mobile phase. Detection is carried out under UV at 25b nm. 

Plants. To remove the insecticide residue on the plant, the plant sample was chopped, and the insecticide residue was extracted with 10% acetone in petroleum naphtha. The crop-solvent was placed in a 1-gallon press-top can with stainless steel baffles and rotated at 45 r.p.m. for 30 minutes. The solvent was decanted off, and the sample was extracted once again. The combined extracts were filtered through filter paper and evaporated in the same manner as the soil extract. Where lipid material was present, the com extracts were re-extracted with acetonitrile. 

ASE has been used for about 8 years. Extractions can be carried out at temperatures ranging from room level (very gentle conditions) to 200°C in order to accelerate extraction, and at pressures over the range 5 to 200 atm in order to maintain the extraction solvent in a hquid state." Residual At-methylcarbamate pesticides in food samples were determined by ASE and LC. The pesticides were extracted with acetonitrile at 100°C at a 2000 psi pressure." ... 

The active eluent from the XAE>-2 column was stripped of volatile solvents and the remaining aqueous mixture was made basic with a few drops of concentrated NaOH. This mixture was extracted with petroleum ether and the oonbined organic phases were back-extracted with acetonitrile vhich was added to the aqueous phase. The aqueous phase was then extracted with acetonitrile. The oorabined acetonitrile phases were dried with a single partition against saturated NaCl (aq.) and reduced in volume. 

Figure 3.6 shows a chromatogram of a mixture of additives found by chromatography of a mixture of additives, solvent extracted with methyl chloride from a sample of polypropylene (PP). The mobile phase was water (channel A) and acetonitrile (channel B). The analysis performed on a Hewlett Packard Model HP109 Series M LC equipped with a diode array detector, shows the presence of methylated hydroxy toluene, methylated hydroxyethyl benzene. Amide E (erucamide), Irganox 1010 and Irganox 1076 (both sterically hindered phenols). 

Purification. For polymerization, butadiene that is at least 99 mol% pure is required. Although alkynes are the most troublesome impurities, separation of the butadiene from other C4 products is also necessary. Simple fractional distillation is effective for removing the light (C3) and heavy (C5) ends from butadiene, but not for removing the various C4 species because of the closeness of the boiling points to each other and to butadiene. Further complicating purification, butadiene forms azeotropes with re-butane and 2-butene. The most widely used recovery systems are extraction with aqueous cuprous ammonium acetate (CAA) and solvent extractions with furfural, acetonitrile, dimethylformamide, dimethylacetamide, or AT-methylpyrrolidinone (65,66). 

These methods invariably have extraction and cleanup procedures that are not optimal for all analytes and for ergot epimerization, low recoveries, and higher LODs are more likely. They typically involve extraction with acetonitrile, evaporation of the solvent, and reconstitution in the LC mobile phase solvent. The detection method is by necessity LC-MS or LC-MS/MS. 

Uhde and co-workers [34, 35] have studied the migration of 4,4 -thiobis-6-tert-butyl-w-cresol (Santonex R) from plastics utensils into sunflower seed oil. Sunflower seed oil that had been stored in vessels of polyethylene containing this antioxidant was diluted (3 5) with pentane and extracted with acetonitrile containing 5 % of water. The concentrated acetonitrile extract (or an ethanol solution of the residue on evaporation) was snbjected to thin-layer chromatography on Kieselgel with hexane-ethyl acetate (10 3) as solvent. To detect the antioxidant (down to 0.1 ppm) the plate was sprayed with 3,5-dichloro-p-benzoquinonechlorimine solution. To determine the antioxidant, the zone at Rf = 0.44 (located by means of iodine vapour) was removed and treated with fuming nitric acid sulfuric acid (1 1). The nitro-derivative of the antioxidant was determined in the product by polarography after the addition of urea and sodium acetate [35],... 

Dried with Linde type 5A molecular sieves or Na2S04 and fractionally distd at reduced pressure. Alternatively, it was refluxed with, and distd from, BaO. Also purified by fractional crystn from the melt and distd from zinc dust. Converted to its phosphate (m 135°) or picrate (m 223°), which were purified by crystn and the free base recovered and distd. [Packer, Vaughn and Wong J Am Chem Soc 80 905 1958.] The procedure for purifying via the picrate comprises the addition of quinoline to picric acid dissolved in the minimum volume of 95% EtOH to yield yellow crystals which are washed with EtOH and air dried before recrystn from acetonitrile. The crystals are dissolved in dimethyl sulfoxide (previously dried over 4A molecular sieves) and passed through a basic alumina column, on which picric acid is adsorbed. The free base in the effluent is extracted with n-pentane and distd under vacuum. Traces of solvent are removed by vapour phase chromatography. [Mooman and Anton J Phys Chem 80 2243 1976.]... 

The solid is separated by filtration and the filtrate is extracted with three 150-ml. portions of ether. Caution Gloves should be worn when handling this solution because of the large amount of cyanide it contains.) The solid is dissolved in ether and this solution is combined with the extracts. The combined ethereal solutions are washed with water and dried over 5 g. of sodium sulfate. Removal of the solvent by distillation leaves crude ferrocenyl-acetonitrile as a solid or as an oil that crystalli/.es on being scratched. I he nitrile is dissolved in about 200 ml. of boiling... 

This method can also be used to analyse soil samples. For instance, fenpropi-morph, which is a non-polar pesticide with good UV sensitivity but poor selectivity, has, after treatment, been determined in soil samples (31). In this example, an amount of soil was extracted overnight with acetonitrile this was then poured into a Buchner filter and rinsed with the same solvent. The acetonitrile solution was concentrated and, prior to LC analysis, the extract was diluted with water and 100 p.1 were then injected into the LC system. 

From empirical observation, ILs tend to be immiscible with non-polar solvents. They can therefore be washed or brought into contact with diethyl ether or hexane to extract non-polar reaction products. Among solvents of greater polarity, esters (ethyl acetate, for example) exhibit variable solubility with ILs, depending on the nature of the IL. Polar or dipolar solvents (including chloroform, acetonitrile, and methanol) appear to be totally miscible with all ILs (excepting tetrachloroaluminate IL and the like, which react). Among notable exceptions, [EMIMJCl and [BMIMJCl are insoluble in dry acetone. 

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