Pentane-dichloromethane

However, in pentane-dichloromethane solution other products are produced,<30,3l)... 

BDE 47, 99 100 Fish (Muscle tissues of salmon and conger eel and liver tissues of sea bass) green mussel Homogenization, MSPD with sodium sulfate, microwave-assisted extraction with pentane-dichloromethane (1 1) and purification with GPC Gas Chromatography (DB-5MS) Q-MS <100 ng/Kg [41]... 

Upon treatment with an ethereal solution of methyllithium, both oligocydopropyl-substituted cyclopentadienes 14 and 6 in tetrahydrofuran were quantitatively deprotonated to the corresponding cyclopentadienides 14-Li and 6-Li, respectively, which were characterized by their 1H and 13 C NMR spectra. Treatment of the solutions of 14-Li and 6-Li with solutions of iron(II) chloride in tetrahydrofuran yielded the l,l, 2,2, 3,3, 4,4 -octacydopropylferrocene (16) (74%) and the decacyclopropylferrocene (17) (21%). After crystallization from hexane (for 16) and pentane/dichloromethane (for 17), the structures of both ferrocenes were established by X-ray crystal structure analyses (Scheme 3). The electron-donating effect of the cyclopropyl substituents on these cyclopentadiene systems is manifested in the oxidation potentials of the ferrocenes 16 and 17. While the parent ferrocene has an oxidation potential E1/2 (vs. SCE) = +0.475 V, that of decamethylferrocene is significantly lower with Ei/2 = —0.07 V, and so are those of 16 (Ey2 — —0.01 V) and 17 (f i/2 = —0.13 V) [13]. 

Compound Ether Pentane/ether Pentane/dichloromethane... 

Pentacarbonyl(diphenyl telluroketone)tungsten(II)3 Under dry nitrogen solutions of 980 mg (2 mmol) of pentacarbonyl(diphenylmethylene)tungsten in 20 ml of dichloromethane and of 1.38 g (2 mmol) of bis[triphenylphosphine]iminium tellurocyanate in 10 ml of dichloromethane, both at — 90°, are combined and stirred for 10 min at that temperature- The mixture is then chromatographed on silica gel at — 50° with pentane/dichloromethane (10 1 v/v) as the mobile phase. The blue fractions are collected, the solvent is distilled under high vacuum, and the residue is recrystallized from pentane, yield 220 mg (18%) m.p. 35° (dec.). 

Biological samples. PCBs can be extracted from biological samples by using acetonitrile or cyclohexane/acetone in an ultrasonic homogenizer and pentane/ dichloromethane or hexane in a Soxhlet apparatus (23, 44-47). 

The experimental conditions used for wine analysis are reported in the literature (Gunata et al., 1985 Versini et al., 1988 Voirin et al., 1992), where both the best particle dimension (i.e. 0.1-0.3 mm) and eluent for the free forms (i.e. pentane/dichloromethane 2 1 v/v), were established. 

The organic samples can also be injected directly into a GC without any preconcentration using a large volume on column system injection. This was tested in the case of liquid-liquid extraction with pentane/dichloromethane (2 1 v/v), by comparing the peak areas obtained with both injection methods for different compound categories present in wines in different levels, such as isoamyl acetate, acetoin, n-hexanol, trans 3-hexenol, cis 3-hexenol, ethyl octanoate, linalool, diethyl succinate, hexanoic and octanoic acids, N(3-methylbutyl)-acetamide, monoethyl succinate, 4-vinylphenol and 4-vinylguaiacol... 

The sample material is diluted with demineralized water and extracted with organic solvent like pentane/dichloromethane by using the fuimel-separator or rotation-perforator method over a longer period. The extract is dried and concentrated by solvent evaporation. The concentrated extract can be applied to GC-analysis. This method is applicable for liquid extracts and flavouring compounds [4]. 

Details on the methods used (extraction, clean-up, separation) are given in the certification report [26]. Extraction was either carried out ultrasonically or by Soxhlet using organic solvent, e.g. hexane, acetone, n-pentane, dichloromethane. Clean-up was performed e.g. by treatment with concentrated H2SO4 followed by desulphurisation, column chromatography with e.g. activated alumina, silica etc. Capillary gas chromatography was used, identifying the CB compounds on the basis of their relative retention times and, in case of mass selective detection, on the basis of their ion masses. In all cases, at least two columns of different polarity have been used for quantification. For each CB, the participant selected the best suited column. 

The within- and between-bottle homogeneity was verified and the variances were compared with the method variance (assessed on the basis of replicate analyses of an extract). A 500 mg portion of the sediment was extracted in a Soxhlet apparatus with 120 mL of a mixture of n-hexane and acetone 90/10 (v/v) for 6 h. The extract was concentrated and taken into a volume of 1 mL iso-octane. The concentrated extract was eluted over 1.5 g fully activated silica with 15 mL of a 85/15 (v/v) n-pentane/ dichloromethane mixture. A first fraction of 7 mL pure n-pentane was discarded. The eluate was concentrated and taken into a volume of 1 mL of acetonitrile. The concentrate was separated by HPLC with a C-18 column (length 25 cm, internal diameter 4.6 mm, particle size 5 mm), with an acetonitrile/water gradient (45/55 to 100/0 (v/v)) associated to a fluorescence and a diode-array absorption detection. No significant difference in the variance of the between- and the within-bottle series and the analytical method itself Therefore, it was concluded that the material is homogeneous for PAHs. 

Liquid-liquid extraction can be performed using as an internal standard 2-undecanone (150 pL of a 100-mg/L ethanolic solution added to 1.5 L of sample). The sample is extracted three times with 60,40, and 40 ml. of pentane for 10 min with stirring. The extracts are collected together and the resulting solution is concentrated to 10 mL at 4°C under vacuum, then concentrated to 500 pL, and purified on silica gel (70-230 mesh, 60A), activated at 120 °C. The wine extract is then passed through the silica column (100 x 10 mm) and four 40-mL fractions are recovered using pentane (I), pentane/dichloromethane... 

II), pentane/dichloromethane 60 40 (III), and pentane/dichlo-romethane 50 50 (IV). Geosmin is recovered in fraction II. This solution is concentrated to 500 pL under a nitrogen flow before GC/MS analysis (Darriet et al., 2000). 

Prior to extraction, water samples were filtered through precleaned Whatman GF/F filters (using pure acetone/n-hexane) in order to remove suspended particulate matter from the aqueous phase. A sequential liquid/liquid extraction procedure was applied to approximately 1000-mL aliquots of the water samples using the solvents n-pentane, dichloromethane and dichloromethane after acidification to pFl 2. Each extraction step was carried out in a separating funnel with 50 mL of the solvent. The third extraction was applied to the pre-extracted water samples after addition of 2 mL of concentrated hydrochloric acid that was pre-cleaned by intense extraction with n-hexane. Subsequently the organic layers were separately dried by filtration over 1 g of anhydrous granulated sodium sulphate (Merck, Darmstadt, FRG) and 50 pL of an internal standard solution containing routinely d34- -hexadecane (6.0 ng/pL), dio-anthracene (5.1 ng/pL) and di2-chrysene (4.7 ng/pL) in n-hexane was added. Acidic compounds in the third extract were methylated by addition of a diazomethan solution and subsequent reconcentration. Prior to GC/MS analyses the extracts were reduced to a final volume of approximately 25 pL by rotary evaporation at room temperature. 

The crude extracts were separated into three fractions by column chromatography (Baker, 2 g silica gel 40 pm) using the following mixtures as the eluent Fraction 1 - n-pentane/dichloromethane 95/5 v/v, fraction 2 -dichloromethane, fraction 3 - methanol. Prior to analysis, 50 pL of an internal standard containing 90 ng/pL d34-hexadecane in n-hexane were added to each fraction, and the volume was reduced to 100 pL by rotary evaporation at room temperature. 

Mobile phase Pentane dichloromethane MeOH containing 0.5% diethylamine 65 29.8 ... 

Sample preparation Adjust pH of 2 mL urine to 11 with 5 M NaOH, extract twice with 10 mL pentane dichloromethane 70 30. Combine the organic layers and evaporate to dryness under a stream of nitrogen, reconstitute the residue in 200 p,L MeOH, inject a 100 jlL aliquot. (Deconjugate 2 mL urine with 500 p,L 100 mM pH 4.5 sodium acetate buffer and 100 p,L Glusulase (90000 U/mL -glucuronidase and 1000 U/mL sulfatase, Du Pont), heat at 37° for 18 h, proceed as before.)... 

Freeze-dried sediment was Soxhlet-extracted with dichloromethane. Concentrated extracts were fractionated by 107 chromatography on alumina/silica gel column. After elution of the aliphatic fraction with pentane, PCBs were eluted with 1 1 pentane-dichloromethane mixture. The fractions were then concentrated to 1 ml using Kuderna-Danish tubes heated in a water bath at 60°C... 

After addition of 4-nonanol (190 pg) as standard, the wine were passed through a solvent washed Amberlite XAD-2 column (1 cm i.d. x 35 cm) with a flow rate of 2.0 ml/min [4]. The column was then rinsed with 100 ml of distilled water to eliminate sugars, acids and other water-soluble compounds. The fractions containing free aroma was eluted by 50 ml of pentane/dichloromethane (2V/1V). The eluate was dried over anhydrous calcium sulfate, eoncentrated to 50 pi under reduced pressure (rotavapor) and then subjected to GC analyses. 

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