Extraction neutral compound

Figure 1 Scheme for solvent extraction with control of pH. After three extractions, neutral compounds remain in the ether phase. This might be followed by hydrolysis with enzyme, acid, or base to break conjugates (glucuronide, sulfate) and repeated extractions (69). 

Figure 1 Scheme for solvent extraction with control of pH. After three extractions, neutral compounds remain... 

Step 3. The neutral components. The ethereal solution (E remaining after the acid extraction of Step 2 should contain only the neutral compounds of Solubility Groups V, VI and VII (see Table XI,5). Dry it with a little anhydrous magnesium sulphate, and distil off the ether. If a residue is obtained, neutral compounds are present in the mixture. Test a portion of this with respect to its solubility in concentrated sulphuric acid if it dissolves in the acid, pour the solution slowly and cautiously into ice water and note whether any compound is recovered. Examine the main residue for homogeneity and if it is a mixture devise procedures, based for example upon differences in volatility, solubility in inert solvents, reaction with hydrolytic and other reagents, to separate the components. 

Ck)ol the alkaline solution resulting from the distillation of the volatile neutral compounds, make it acid to litmus with dilute sulphuric acid, and add an excess of solid sodium bicarbonate. Extract this bicarbonate solution with two 20 ml. portions of ether remove the ether from the combined ether extracts and identify the residual phenol (or enol). Then acidify the bicarbonate solution cautiously with dilute sulphiu-ic acid if an acidic compound separates, remove it by two extractions with 20 ml. portions of ether if the acidified solution remains clear, distil and collect any water-soluble, volatile acid in the distillate. Characterise the acid as under 2. 

Step 3. The non-steam-volatile compounds. The alkaline solution (82) remaining in the distiUing flask from Step 2 may contain water-soluble, non-volatile acidic, basic or neutral compounds. Add dilute sulphuric acid until the solution is just acid to Congo red, evaporate to dryness, and extract the residual solid with boiling absolute ethyl alcohol extraction is complete when the undissolved salt exhibits no sign of charring when heated on a metal spatula in the Bunsen flame. Evaporate the alcoholic solution to dryness and identify the residue. 

Hydroxyquinoline, having both a phenolic hydroxyl group and a basic nitrogen atom, is amphoteric in aqueous solution it is completely extracted from aqueous solution by chloroform at pH < 5 and pH > 9 the distribution coefficient of the neutral compound between chloroform and water is 720 at 18 °C. The usefulness of this sensitive reagent has been extended by the use of masking agents (cyanide, EDTA, citrate, tartrate, etc.) and by control of pH. 

The phenolic and related components present in stems and leaves of sunflower, Helianthus annuus L., and Jerusalem artichoke, Helianthus tuberosus L., were extracted sequentially and their activity as phytotoxic agents evaluated. Total acids and neutral compounds were isolated by extraction with methanol, acetone, and water. The free acids and neutral compounds were partitioned into the organic phase, whereas the acids, present as esters and aglycones, were liberated by subsequent alkaline hydrolysis of the aqueous phase. 

After alkaline hydrolysis and extraction of acidic and neutral compounds, the samples were submitted to GC/MS analyses. They gave similar chromatographic patterns, as shown in Figure 7.3. 

Crisp et al. [212] has described a method for the determination of non-ionic detergent concentrations between 0.05 and 2 mg/1 in fresh, estuarine, and seawater based on solvent extraction of the detergent-potassium tetrathiocyana-tozincate (II) complex followed by determination of extracted zinc by atomic AAS. A method is described for the determination of non-ionic surfactants in the concentration range 0.05-2 mg/1. Surfactant molecules are extracted into 1,2-dichlorobenzene as a neutral adduct with potassium tetrathiocyanatozin-cate (II), and the determination is completed by AAS. With a 150 ml water sample the limit of detection is 0.03 mg/1 (as Triton X-100). The method is relatively free from interference by anionic surfactants the presence of up to 5 mg/1 of anionic surfactant introduces an error of no more than 0.07 mg/1 (as Triton X-100) in the apparent non-ionic surfactant concentration. The performance of this method in the presence of anionic surfactants is of special importance, since most natural samples which contain non-ionic surfactants also contain anionic surfactants. Soaps, such as sodium stearate, do not interfere with the recovery of Triton X-100 (1 mg/1) when present at the same concentration (i.e., mg/1). Cationic surfactants, however, form extractable nonassociation compounds with the tetrathiocyanatozincate ion and interfere with the method. 

A neutral organic. If you ve extracted strong acids first, then weak acids, then bases, there are only neutral compound(s) left. If possible, just remove the solvent that now contains only your neutral compound. If you have more than one neutral compound, you may want to extract one from the other(s). You ll have to find two different immiscible organic liquids, and one liquid must dissolve ONLY the neutral organic compound you want A tall order. You must count on one neutral organic compound being more soluble in one layer than in the other. Usually the separation is not clean—not complete. And you have to do more work. 

The extraction of environmental or geological particulate matter with solvents, solvent mixtures or supercritical carbon dioxide is the preferred method, because it results in minimum alteration of its polar components, avoids hydrolysis of anhydrides, esters, etc. and is highly efficient for most organic compounds (even sugars). Other workers have reported the direct vaporization by thermal desorption or flash pyrolysis of organic compounds from particulate matter into GC, MS, or GC-MS instruments. Those methods work fine for neutral compounds (e.g. hydrocarbons) but should be used with caution when analyzing polar or labile compounds. 

A neutral compound has a partition coefficient of 5 between ether and water. What percentage of the compound would be extracted from 10 ml of water if (i) 30 ml of ether were used to extract the compound or (ii) three 10 ml volumes of ether were used in succession to extract the compound ... 

Neutral compounds can be extracted without controlling pH. Washing can be carried out with dilute acid or alkaline buffer (to remove ionisable impurities) and methanol water mixtures. The compounds can be eluted from the column with methanol, ethanol or chloroform. 

Other sulfonamides. The fact that the extraction of one of these sulfonamides is only optimized at a totally different pH displays the compilations in relying on a single set of extraction conditions as representative for all members within each class of PPCPs. To trap acid components in the sample, the sample has to be acidified to pH < 2, passed through a conditioned column such as an RP C18 solid-phase extraction column, and then eluted with a volatile solvent. Neutral compounds are, on the other hand, extracted by adjusting the sample to pH 7-8 before ranning the sample through the extraction column, which has been conditioned with acetone, methanol, or distilled water. Basic compounds are extracted by initially adjusting the sample to pH > 12 with EDTA and KOH. 

The acetylacetone complex Be(acac)2 is a neutral compound with an organic ligand, and hence is extractable from HOH into immiscible non-aqueous solvents such as benzene, carbon tetrachloride, chloroform, and diethylether. 

Separation of aniline and a neutral compound from a mixture by solvent extraction... 

If a mixture contains aniline and a neutral compound, both the constituents can easily be separated and purified by the solvent extraction method. To purify these compounds, the mixture is dissolved in diethylether, HCl and water are added and the solution is shaken in a separating funnel. Once two... 

Hydrochloric acid extract. This will contain any basic components present. Render alkaline with 10-20% NaOH and extract with ether. Ether solution (Et). This will contain any neutral compounds present. Dry with anhydrous magnesium sulphate, and distil off the ether. A residue indicates... 

This sample pretreatment is devoted mainly to organic compounds that can be removed from an aqueous solution by extracting them into a water-immiscible solvent. Chelation or ion pairing between large and poorly hydrated ions and chelating agent may form neutral compounds that can be extracted by organic solvents. 

Treat the solution (R i) remaining in the distilling flask after the volatile acidic and neutral compounds have been removed with 10-20 per cent sodium hydroxide solution until distinctly alkaline. If a solid separates, filter it off and identify it. Distil the alkaline solution until no more volatile bases pass over (distillate no longer turbid, or not basic to litmus water-soluble bases also possess characteristic odours) add more water to the contents of the flask if the solution becomes too concentrated during this distillation. [Set aside the solution in the distilling flask (S2) for Step 3.] If the volatile basic compounds are insoluble in water, remove them by extraction with two 20 ml portions of ether, and identify the bases (compare Sections 9.6.21, p. 1273 and 9.6.22, p. 1278) after evaporation of the ether. The water-soluble amines may be identified with phenyl isothiocyanate it is best to concentrate the bases by redistilling and collecting the first half of the distillate separately. 

Extraction of Nuclides by Mixture of Acids and Neutral Compounds.361... 

EXTRACTION OF NUCLIDES BY MIXTURE OF ACIDS AND NEUTRAL COMPOUNDS... 

This is applied to separate acidic or basic organics from neutral organics. The solvent extract is shaken with water that is highly basic. The acidic organics partition into the aqueous layer whereas, the basic and neutral compounds stay in the organic solvent and separate out. After this, the aqueous layer is acidified to a pH below 2, and then extracted with methylene chloride. The organic layer now contains the acid fraction Phenols, chlorophenoxy acid, herbicides, and semivolatile organic pollutants are cleaned up by the procedure described above. 

A 100-mL sample aliquot adjusted to pH 11.5 sample extracted with methyl tert-butyl ether (MTBE) chloroacetic acid partitions into aqueous phase basic and neutral compounds in MTBE phase discarded the aqueous phase now adjusted to pH 0.5 and extracted again with MTBE the MTBE extract dried and concentrated chloroacetic acid in the MTBE extract esterified with diazomethane the methyl ester determined by capillary GC on an ECD (U.S. EPA Method 552, 1990). 

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