Dichloromethane extractables from

Dry the dichloromethane extract from Section 6.1.3 with anhydrous sodium sulfate and collect the solution in a 1-L round-bottom flask. Evaporate the solvent at 37 °C under reduced pressure. Dissolve the residue in 4 mL of acetone-n-hexane (1 9, v/v) and adsorb on the top of a silica gel column bed. Rinse the flask three times with 1 mL of the solvent mixture and transfer the rinsings to the column. Elute interfering substances with 85 mL of the solvent mixture and discard the eluate. Then elute fluthiacet-methyl with 140 mL of the solvent mixture. Collect the eluate in a 300-mL... 

The bioassay-guided fractionation of the antifungal dichloromethane extract from the roots of Vernonanthora tweedieana (Baker) H. Rob. allowed the isolation of one active sesquiterpene, identified as 6-cinnamoyloxy-l-hydroxyeudesm-4-en-3-one, Fig. (9) [162]. MIC values of this eompound showed Trichophyton mentagrophytes as the most sensitive strain. 

Bioassay-guided fractionation of the antimicrobial dichloromethane extract from Xanthium spinosum L. yielded xanthatin, Fig. (22) [194]. This compound was active against Colletotrichum gloesporoides, Trichotecium roseum. Bacillus cereus and Staphylococcus aureus. These compounds together with another sesquiterpene lactone xanthinin, Fig. (23) were also isolated from Xanthium italicum Moretti [195]. 

In the marine environment there has been the first reported occurrence of so-called antifouling (namely, anticrustaceous activity) by (15 0)-anacardic acid. Thus bioassay-directed fractionation of the dichloromethane extract from twigs of Ozoroa insignis containing the phenolic lipid, was used with larvae from Artemia salina as a model to investigate the activity [296]. 

The dichloromethane extract from Wilbrandia ebracteata (p.o.) significantly reduced the paw elevation time (1 mg/kg) and cell influx (10 mg/kg) in zymosan-induced arthritis in rats. The same extract inhibited COX-2 activity, as measured by PGE2 production, without affecting that of COX-1. Moreover, nitrite release was clearly and significantly reduced at a dose of 10 mg/kg (p.o.). The analysis of the pharmacological data, together with the HPLC analysis of the extracts, points to an anti-inflammatory effect based on an associated reduction in nitric oxide (NO) release and COX-2 inhibition by the cucurbitacins... 

Both the extracts containing cucurbitacins and the isolated compounds themselves have been reported as analgesic agents. The dichloromethane extract from Wilbrandia ebracteata roots administered i.p., for example, had an analgesic effect in the acetic acid writhing test in mice, reducing... 

Figure 3. Reconstructed ion chromatograms from GC/MS analysis of vapor phase organic extractable from Tenax (upper trace) and dichloromethane extractables from glass fiber Tenax filter (lower trace). Samples of the raw gas collected after the cyclone. A 25 m OV-101 quartz capillary column was used in a Finnigan model 4023 gas chromatograph mass spectrometer. Temperature program was 2 min at 50°C, 5°C/min to 270°C with 15 min at 270 C.

Cleanup Device Samples. The percent dichloromethane extractables from solid and liquid samples collected by the gasifier cleanup devices are given in Table VI. A portion of the dichloromethane extractables from the Venturi scrubber decanter outlet water was fractionated on the Sephadex LH-20 column. The organic compounds in this sample eluted from the column primarily (approximately 80%) in Fraction 5. A portion of Fraction 5 was subfractionated into acidic, basic and neutral components. This resulted in 15 percent of the mass recovered in the acidic subfraction, 1.5 percent in the basic subfraction, 11 percent in the neutral subfraction and the remaining 72.5 percent being water soluble. Many nitrogen heterocycles were also found in the basic subfraction by 6C/MS analysis. 

Dichloromethane Extractables From Gasifier Cleanup Device Samples... 

Seventy bioassays of dichloromethane extracts of estrous urine re-sus-pended in water or saline elicited a mean of 6.2 flehmen responses per 30 minutes (total session = 60 minutes). When the extract was re-suspended in anestrous urine, a mean of 6.5 flehmen responses were elicited. No differences in responses were recorded when a dichloromethane extract from pooled estrous urine of different cows was compared with a dichloromethane extract from the urine of a single cow. Anestrous urine extracts re-pre-sented in water, saline, or anestrous urine elicited no responses in ten bioassays. Percent recovery in the extract from pH 5.5 urine was high (Table 2). 

The extraction mixture is centrifuged at 2500 rpm for 10 min. The dichloromethane layer (bottom layer) is carefully removed and saved. Into the MeOH and aqueous layer of each test tube, an additional 2 mL of dichloromethane is added and the dichloromethane layer is separated as above. The dichloromethane extracts from each identical sample are combined and dried under a nitrogen stream. Each individual residue is then resuspended in 4 mL of dichloromethane-methanol (1 1), re-extracted against 1.8 mL of 10 mM LiCl... 

Figure 3.7 [continued) (b) Chromatograms of (iii) the dichloromethane extract of strawberry fruit yoghurt analysed with an apolar primary column, with the heart-cut regions indicated, and (iv) a non-racemic mixture of y-deca-(Cio) and 7-dodeca-Cj2 lactones isolated by heart-cut transfer, and separated by using a chiral selective modified cyclodextrin column. Reproduced from A. Mosandl, et al J. High Resol. Chromatogr. 1989, 12, 532 (39f. 

Figure 10.1 Analysis of racemic 2,5-dimethyl-4-hydroxy-3[2H]-furanone (1) obtained from a strawbeny tea, flavoured with the synthetic racemate of 1 (natural component), using an MDGC procedure (a) dichloromethane extract of the flavoured strawbeny tea, analysed on a Carbowax 20M pre-column (60 m, 0.32 mm i.d., 0.25 p.m film thickness earner gas H2, 1.95 bar 170 °C isothermal) (b) chirospecific analysis of (1) from the sti awbeny tea exti act, ti ansfened foi stereoanalysis by using a pemiethylated /3-cyclodextrin column (47 m X 0.23 mm i.d. canier gas H2, 1.70 bar 110 °C isothemial). Reprinted from Journal of High Resolution Chromatography, 13, A. Mosandl et al., Stereoisomeric flavor compounds. XLIV enantioselective analysis of some important flavor molecules , pp. 660-662, 1990, with permission from Wiley-VCH.

The formation of the acyl azide may be followed by the growth of the 2130-cm. (—N=N=N) infrared absorption of concentrated dichloromethane extracts of aliquots removed from the reaction. 

Metabolites may also play a role in the association of the substrate with humic and fulvic acid components. Two illustrations are given (a) naphth-l-ol, an established fungal metabolite of naphthalene, may play a role in the association of naphthalene with humic material (Burgos et al. 1996) and (b) it has been shown that C-labeled metabolites of [9- C]-anthracene including 2-hydroxyanthracene-3-carboxylate and phthalate were not extractable from soil with acetone or dichloromethane, and required alkaline hydrolysis for their recovery (Richnow et al. 1998). 

Acetochlor and its metabolites are extracted from plant and animal materials with aqueous acetonitrile. After filtration and evaporation of the solvent, the extracted residue is hydrolyzed with base, and the hydrolysis products, EMA and HEMA (Figure 1), are steam distilled into dilute acid. The distillate is adjusted to a basic pH, and EMA and HEMA are extracted with dichloromethane. EMA and HEMA are partitioned into aqueous-methanolic HCl solution. Following separation from dichloromethane, additional methanol is added, and HEMA is converted to methylated HEMA (MEMA) over 12 h. The pH of the sample solution is adjusted to the range of the HPLC mobile phase, and EMA and MEMA are separated by reversed phase HPLC and quantitated using electrochemical detection. 

Residues of flumioxazin are extracted from plant matrices with aqueous acetone. The extracted residues are partitioned into dichloromethane. The dichloromethane is removed through rotary evaporation. Partitioning between hexane-acetonitrile followed by Florisil column chromatography purifles the plant extract. Residues of flumioxazin are quantitated by gas chromatography GC. 

Flumioxazin is extracted from water with dichloromethane. If needed, the sample is cleaned with Florisil column chromatography prior to quantitation by GC. 

Transfer the filtrate from Section 6.1.1 or 6.1.2 to a 500-mL separatory funnel and add 150 mL of 5% aqueous sodium chloride solution. Rinse the filter flask from the extraction procedure with two 40-mL portions of dichloromethane. Add both 40-mL rinses to the separatory funnel. Partition the residue into the dichloromethane. Filter the dichloromethane extract through a 10-cm filter funnel containing ca 50 g of anhydrous sodium sulfate supported on a plug of glass wool. Collect the dichloromethane in a 500-mL round-bottom flask. Repeat the partition and filtration steps with an additional 60 mL of dichloromethane. Rinse the sodium sulfate filter cake with 20 mL of dichloromethane and combine the partition and rinse solvents. Concentrate the combined dichloromethane solvents to dryness in a rotary evaporator under reduced pressure at <40 °C. 

Another GC/MS method that was validated as a food tolerance method involved the determination of glyphosate and (aminomethyl)phosphonic acid (AMPA) in crops. In this method, glyphosate and AMPA residues are extracted from crop commodities (corn grain) with water. The extracts are then partitioned with dichloromethane,... 

Hymexazol residues are extracted from plant materials with acetone and partitioned into aqueous sodium hydrogen carbonate solution. The aqueous solution is washed with dichloromethane and diethyl ether. After acidification of the... 

Plant samples are homogenized with sodium hydrogencarbonate aqueous solution to prevent decomposition of the analytes during homogenization. Imibenconazole and its primary metabolite, imibenconazole-debenzyl, are extracted from plan materials and soil with methanol. After evaporation of methanol from the extracts, the residues are extracted with dichloromethane from the residual aqueous solution. The dichloromethane phase is cleaned up on Florisil and Cig columns. Imibenconazole and imibenconazole-debenzyl are determined by gas chromatography/nitrogen-phosphorus detection (GC/NPD). 

Transfer the residue derived from Section 6.1.1 or 6.1.2 into a 200-mL separatory funnel with 80 mL of water and add 5 g of sodium chloride. Adjust the pH of the aqueous phase to 6-8 with saturated aqueous sodium hydrogencarbonate solution. Extract the aqueous phase successively with 50 and 30 mL of dichloromethane by shaking the funnel with a mechanical shaker for 5 min. Combine the dichloromethane extracts and dry with anhydrous sodium sulfate. Transfer the extracts into a 100-mL round-bottom flask and concentrate the extracts to near dryness by rotary evaporation. Dissolve the residue in 2 mL of n-hexane. 

Transfer the soil extract (from Section 6.1) into a 1000-mL separatory funnel, add 200 mL of water and 10 mL of saturated sodium chloride solution, and extract the sample with 100 mL of dichloromethane three times. Dry the dichloromethane extract with anhydrous sodium sulfate in a funnel in a similar manner as described for juice, pulp and rind, and collect the dried solution in a 500-mL round-bottom flask. Evaporate the dichloromethane under reduced pressure. Dissolve the residue in 3 mL of benzene. 

Theobromine was determined by GC in various foods (bitter chocolate, milk chocolate, chocolate cake, cocoa powder, chocolate milk), and results are given in graphs and tables.27 Homogenized samples were boiled in alkaline aqueous media, then fat was extracted with n-hexane. The aqueous layer was acidified with diluted HC1 and NaCl was added. Theobromine was extracted from this treated aqueous solution with dichloromethane and the extract was evaporated to dryness. The residue was redissolved in dichloromethane containing an internal standard. GC analysis was performed on a column packed with 1% cyclohexane dimethanol succinate on Gaschrom Q, with FID. Average recoveries were 99 to 101%, coefficient of variation was less than 3% and the limit of detection for theobromine in foods was about 0.005%. 

Figure 10.6 Total ion chromatograms obtained for frankincense showing comparison between (a) SPME and (b) dichloromethane extraction. Reproduced from S. Hamm, E. Lesellier, j. Bleton, A. Tchapla, J. Chromatogr., A, 1018, 73 83.Copyright 2003 Elsevier Limited...

---