Heptane extraction

Following the same procedures described in the above-mentioned study, additional extractive data were obtained for the epoxy phenolic enamel that was irradiated at 4.7-7.1 Mrad at 25 and — 30 °C in the presence of distilled water, 3% acetic acid, and n-heptane. The changes in the amount of extractives resulting from the irradiation treatment are shown in Table IX. In the case of the water and acetic acid extractives, there was no change in either the chloroform-soluble fractions or the chloroform-insoluble fractions. In the case of the n-heptane extractives, the amount of extractives decreased when the irradiation temperature was reduced from +25 to — 30°C. Infrared spectra of the chloroform-soluble residues from the water and acetic acid extractives of the unirradiated and irradiated enamel were identical to the chloroform-soluble residues from the solvent blanks. In other words, the epoxy phenolic... 

Superoxide dismutase Bovine red blood cells AOT/heptane Extraction and purification [68]... 

Spm metric detector (Au and IonPac CG10 guard His 12 ng Spm heptane extraction, cen- ... 

The heptanic extract was recovered by evaporating the solution in a calibrated flask until we obtained a solvent-free film adhering to the walls. 

Figure 2 shows the variation with time of the amount of grafted rubber measured on the basis of the amount of n-heptane-extractable rubber at 60 °C. The behavior is asymptotic, and for ethylene-propylene copolymers the yield of grafted rubber never exceeds 60%. 

Figure 1. The effect of temperature on the separation factor (ff) for n-heptane extraction of acid mine water (pH = 2.35)...

The angular furanocoumarin dorstegin (41) was also isolated from the n- heptane extract. NOE irradiation of H-4 in 41 caused an enhancement of H-4 suggesting the pyran ring annelation at position 5 and 6. Ten... 

The normal phase HPLC (20% chloroform in heptane) could separate A9-tetrahydrocannabinol from monohydrox-ylated metabolites and from 11-hydroxy-A tetrahydrocannabinol. However, a minor overlap could be avoided by collecting the tetrahydrocannabinol 1 in a slightly narrower volume range. The prior heptane extraction of alkalinized plasma had separated these non-polar constituents from any acidic metabolite. This separation of plasma extracts and normal phase HPLC collection of volumes in the appropriate range resulted in a substantial reduction in GLC background from plasma components for derivatized tetrahydrocannabinol analyzed with electron capture (63 1) detection. 

The heptane extraction efficiency from plasma was highly reproducible over a wide range of plasma concentrations - 100 ng/ml) 90.6 0.7% (SEM). 

The recovery of 1 from the heptane extract of dog plasma by normal phase HPLC was reproducible over the range of plasma concentrations studied. Equivalent overall recoveries were obtained by both radiochemical analysis (83.7 1.8% SE) and electron-capture GLC analysis (84.0 4.9% SE) of the derivatized tetrahydrocannabinol. ... 

Both methods permitted estimation of a 92.5% recovery of the amount in the heptane extract injected on HPLC and collected in the chosen range. 

A similar study of the reproducibility of collection of 14c 9 tetrahydrocannabinol in plasma assayed by liquid scintillation after extraction and reverse-phase HPLC was also conducted. The amounts recovered were proportional to the amounts injected, and the HPLC recovery efficiency of the drug in the heptane extract was 95.7%. 

The plasma of a dog intravenously administered solutions of l c-A -tetrahydrocannabinol was monitored with time after heptane extraction by both radiochemical analysis and electron-capture GLC of the derivative of the appropriately collected eluate fraction from normal phase HPLC. Typical plots of the time course of the results from both methods are given in Figure 7. 

Methyl derivatives were used by Martin and Driscoll [509] they were prepared by treatment with dimethyl sulphate and applied to the analysis of barbiturates in serum, as follows. A 2-ml volume of a saturated solution of sodium dihydrophosphate and 10 ml of diethyl ether were introduced into a test-tube containing 2 ml of serum. The test-tube was closed and shaken vigorously for 30 sec, centrifuged for 1 min, then 7 ml of the extract were transferred into another test-tube and the ether was removed in a stream of air in a water-bath. The residue was dissolved in 2 ml of methanol with 10% of water (v/v), saturated with potassium carbonate, and 0.1 ml of dimethyl sulphate were added and the mixture was heated in a water-bath at 60°C for 4 min. At this temperature methanol was removed in a stream of air (3 min) and the residue was extracted into 1.5 ml of -heptane with the addition of 1 ml of 1 M acetate buffer (pH 6). A 1 -ml volume of the n-heptane extract was transferred into a small test-tube, evaporated carefully in order that losses of the derivatives might be avoided, and dissolved in 100 (A of acetone (containing an internal standard if necessary) 5 jul were analysed on a column packed with 5% of SE-30 at 175°C. 

Once laid, the polystyrene films were further purified by exhaustive extraction with methanol or n-heptane the progress of extraction was followed by the ultraviolet spectra of the extracts. These preirradiation extractions showed considerable variation in purity among the three polystyrenes in spite of reprecipitation measures. The degree to which solvents can remain with a 20/ film is suggested by the need of seven days of continuous methanol or n-heptane extraction to remove all of the extractable benzene from a film laid from that solvent and dried in vacuum at 65°C. for 24 hours. For film laid from methylene chloride, an optically clean n-heptane extract was obtained from the AIBN-ini-tiated sample within a few hours, but up to 48 hours were required for the benzoyl peroxide-initiated samples. The extracted 20/ polystyrene films were essentially non-absorbing above 285 m/, no absorption attributable to material other than polystyrene could be observed, and only one peak (337 m/ ) was seen in the fluorescence spectrum in methylene chloride. Once the films were purified by extraction, the products and wettability changes resulting from irradiation were the same for all polystyrene samples and were independent of the solvent from which the films were laid. 

Literature values of the contact angles for various liquids on four of the five polymers used in this work are given in Table I. These values may be compared with those for our unirradiated polymers. In the case of polystyrene, exhaustive methanol or n-heptane extraction followed by drying did not result in a change in contact angles, and residual extractant could not be observed by means of frustrated multiple internal reflectance (FMIR) spectra of the films. 

Figure 2. Chromatograms obtained by direct analysis of heptane extracts of the sex pheromone glands of pickleworm and melonworm females on a 60 m x 0.25 mm (ID) DB-1 column (J W Scientific, Inc., Rancho Cordova, CA 95670). 1. (E)-ll-hexadecenal ...

The compound can be purified [from any residual tris(diethyldithiocarba-mato) iron(III) which is always present in these samples] and recrystallized simultaneously by doing a Soxhlet extraction with -heptane. The compound (6.5 g) in the Soxhlet extractor is extracted with 150 ml of heptane for 24 hr. Dark-green crystals separate from the heptane extract and can be collected on a filter. Yield about 4.5 g. 

Bk D2EHPA( ) in heptane Extraction of Bk( IV) from strong HNQ3 solution in presence of KBrOs - possibility of separating Bk from Cm and Cf... 

Extractions may be introduced into a work-up to provide for greater safety in operations. For instance, unreacted 1,4-dibromobutane was conveniently removed by heptane extraction of an aqueous phase containing the intermediate lithium carboxylate (Figure 10.8) [11].Without this step, the lachrymator 1,4-dibromobutane (bp 63—65°C/6 mm) was ineffectively removed. On scale this compound would have been very irritating to personnel, especially those removing the product from a dryer. 

DFI Kohl and PM Wood (1969) On the molecular identity of ESR signal II observed in photosynthetic systems The effect of heptane extraction and reconstitution with plastoquinone and deuterated plastoquinone. Plant Physiology 44 1439-1445... 

Catalyst Catalyst Original copolymer Ether extract Hexane extract Heptane extract Residue... 

Extraction of water from an aqueous solution of ethanol Extraction of water from solutions of alcohols and acetone Extraction of water from an aqueous solution of ethanol Extraction of water from solutions of ethanol, pyridine Separation of Cs isomers Separation of benzeneM-heptane Extraction of water from an aqueous solution of ethanol Extraction of water from solutions of ethanol, acetic acid Separation of dichloroethane/trichloroethylene mixtures Extraction of water from solutions of ethanol, acetic acid Extraction of water from an aqueous solution of ethanol Extraction of water from an aqueous solution of ethanol Extraction of 1 -propanol, ethanol from an aqueous solution Extraction of water from solutions of ethanol and acetic acid... 

Heptane extraction. PP material was dissolved in boiling xylene, was precipitated by adding excess methanol, and was extracted with n-heptane (5). 

Determination of Free Rubber. The residue from the methyl ethyl ketone extraction was dried and weighed it was then placed in contact with excess n-heptane at room temperature for 24 hrs. The insoluble fraction was separated by filtration after being washed and dried, it was weighed. The supernatant was evaporated in a calibrated flask, and a thin film of n-heptane-extracted rubber remained. From the data, the amount of grafted, crosslinked polymer was calculated, and its composition was determined. 

Furthermore, the solvent used in many leaching experiments has been toluene, in which many metallocene—MAO catalysts have some solubility, especially at high Al/M ratios. However, to the best of the author s knowledge, few if any commercial polymerization processes use toluene as a diluent. Aliphatic hydrocarbons, bulk monomers, and fluidizing gas streams are used in large-scale plants. Especially at the lower excess of aluminum used in many supported catalysts (50—200 1), metallocene— MAO catalysts are insoluble in hydrocarbon solvents. The heptane extracts from a Cp2ZrCl2—MAO catalyst supported on silica showed no activity in ethylene polymerization, even when additional MAO was added. 

Sweet Chili Miscella - Concentrates were prepared at reduced pressure only. Initial attempts to use the miscella as obtained from the supplier were unsuccessful. When the miscella was combined with distilled water and the mixture was heated with stirring, an intractable gel formed. Subsequently, a hexane fraction was first distilled from the starting material at reduced pressure. Pepper volatiles entrained in this distillate were later reclaimed by careful fractional re-distlllatlon of the hexane fraction. The residue from this fractional distillation was combined with the heptane-extracted material obtained with the steam distillation-extraction head. 

An examination of Table 1 reveals some interesting trends. As the solubility parameter of the extraction solvent increases, the mesophase content of the extracted fraction goes to >99%. Samples 3, 4, 5 and 6 are "neomesophases"0) in that upon melting, they instantly transform to a liquid crystalline state. Their quinoline insolubles contents were less than 1%. The extraction process breaks down the micelle and removes the non-mesomorphic species in the pitch which had inhibited the coalescence of the mesophase forming species. Sample 2, the heptane extracted fraction, did not exhibit neomesophase behavior. Extended heat treatment at 400+ C was required to convert this sample to a mesomorphic state. The heptane did not remove a sufficient amount of the non-mesophase formers. 

Several experiments have involved measurement of photosynthetic parameters during modification of lamellar lipids. Unfortunately the methods are, at present, extremely crude, which makes the interpretation of results rather difficult. Thus, experiments with solvent extraction of chloroplasts may reveal no apparent changes in the morphology of the organelle (Magree et al., 1966). At the same time, heptane-extracted chloroplasts show a lipid... 

Organic extraction methods The w-butanol/heptane extraction for 5-HT in which 5-HT (and catecholamines) are finally extracted into acid (Curzon and Green, 1970) has been modified for LC by simple reduction of the volumes involved (Ponzio and Jonsson, 1979 Marsden, 1981). Other organic solvent extractions previously described have been adapted to the chromatographic methods. These include extraction of amine metabolites into ethyl acetate followed by evaporation to dryness (Cross and Joseph, 1981) and homogenization in formic acid/acetone (15 85 v/ v) followed by centrifugation and evaporation for the determination of NE, DA, 5-HTP, 5-HT, and 5-HIAA (Loullis et al., 1979). In both cases the residues were resuspended in samples of the mobile phase prior to injection onto the column. 

Table 1 Sphemlite nucleation density of isotactic polypropylene of A4 =51 200, heptane extracted, melt annealed before crystallization at 180°C for 15 min. (von Falkai, B. and Stuart, H.A. (1959) Kolloid Zeitschrift, 162,138-140)...

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