Chloroform extract chromatograms

Semenov et al. [8] determined small amounts of petroleum products in chloroform extracts of non saline water by extracting the sample (200-500mL) followed by thin layer chromatography on alumina. He developed the chromatogram with light petroleum-carbon tetrachloride-acetic acid (35 155 1), and examined the plate in ultraviolet radiation the petroleum products exhibit three zones (pale blue, yellow and brown). Each zone is then extracted with chloroform, the fluorescence of the extracts measured and the results referred to a calibration graph. The sensitivity is O.lmg L. The infrared and fluorescence spectra of the zone obtained with various petroleum products are discussed. 

Figure 5. A gas chromatogram of the chloroform extract of cysteamine-treated decaffeinated coffee. Peak 1 = 2-methylthiazo-lidine, 2 = thiazolidine, S = internal standard, 3 = 2-acetyl-thiazolidine, 4 = 2-furfurylthiazolidine.

Figure 6. A gas chromatogram of the chloroform extract of cysteamine-untreated decaffeinated coffee.

Reference Solutions. Prepare chloroform solutions containing standard mixtures of drugs, all at concentrations of 5 iLig/ml, and inject 3 to 5 Lil on to both columns to obtain the standard chromatogram. Method. To 100 Ll1 of stomach contents or 500 Lil of urine add 100 Ll1 of M sodium hydroxide, and extract with 100 Lil of chloroform by the micro-exfraction method (above) inject 3 to 5 ll1 of the chloroform extract on to both columns. Identify any peaks which appear on the chromatograms by reference to the standard chromatogram and to the retention data given on p. 193. Corroborative evidence must be obtained from both systems. 

The test may be carried out directly on the residue from the alkaline-chloroform extract, or on the spot on a paper or thin-layer chromatogram, or on the material eluted from such a spot. Colors from crude extracts always tend to be duller than those obtained from pure materials owing to the charring of the impurities by the sulfuric acid. 

Place 20 pi of the chloroform extract of the polyethylene sample as a spot on a thin-layer plate. Also apply 20 pi aliquots of standard solutions of Santonox R in chloroform (0.05%, 0.04%, 0.03% w/v). Develop the chromatogram to a distance of 10 cm in a chromatography tank containing petroleum ether (40 60)/ethyl acetate (5 1 viv mixture) as the eluent. 

FIGURE 3.33 (a) Total-ion chromatogram of a chloroform extract of a wood sliver from a telephone pole for determination of pentachlorphenol (b) expanded view of chromatogram ranging from 20 to 25 min. Peak at retention time of 20.14 min was determined to be pentachlorphenol. Conditions 30-m x 0.25-mm-i.d. DB-5 column with 0.25-u.m film. Column conditions 40°C at 8°C/min to 250°C after 1 min isothermal hold splitless injection of 1 aL (1 min delay time). 

Neutral and basic herbicides were extracted from water made alkaline with sodium hydroxide or from soil, with chloroform extracts of soil were cleaned up on a basic alumina containing 15% of water. Acidic herbicides were extracted with ethyl ether from water acidified with hydrochloric acid or from an aqueous extract of soil prepared by treatment with 10% aqueous potassium chloride that was 0.05m in sodium hydroxide and filtration into 4m hydrochloric acid. The concentrated chloroform solution of neutral and basic herbicides was applied to a pre-coated silica gel plate containing a fluorescent indicator and a chromatogram was developed two-dimensionally with hexane-acetone (10 3) followed after drying by chloroform-nitromethane (1 1). The spots were detected in ultraviolet radiation. Atrazine, Barban, Diuron, Linuron, Monouron, Simazine and Trifluralin were successfully separated and were located as purple spots on a green fluorescent backgroimd. The ether extracts were dried over sodium sulphate. 

Aroclor 1248, Aroclor 1254, and Aroclor 1260. Quantitation is by comparison of chromatograms with standard concentrations of pure compounds treated in an identical manner. The phenoxy acid herbicides (2,4-dichlorophenoxy)acetic acid (2,4-D), sUvex, and (2,4,5-trichlorophenoxy)acetic acid (2,4,5-T) can be deterrnined by electron-capture detection after extraction and conversion to the methyl esters with BF.-methanol. The water sample must be acidified to pH <2 prior to extraction with chloroform. 

Figure 2.21 shows the on-line extraction gas chromatogram of 2.25 ml of water spiked at 5 ppb levels with 14 different organic pollutants (40). In this case, the authors concluded that wall-coated open tubular traps (thick-film polysiloxane phases) can be used for the on-line extraction of organic compounds from water. However, when using swelling agents such as pentane, non-polar analytes can be trapped quantitatively, while for more polar compounds chloroform is the most suitable solvent. 

Figure 5. Chromatograms for theophylline in plasma extracts. Arrow indicates tneophyUine peak. Conditions 50 cm X 3 mm (i.d.) column with 10 fjm silica gel (Micropak Si 10 Varian) mobile phase, 84/15/1 chloroform/isopropanol/acetic acid flow rate, 40 rm/hr detector, UV,273nm(40).

Figure 4. Thin layer chromatogram (TLC) tracing of the DEAR extract extracted with ether and controls on silica gel plates. Developing solvent was chloroform ace-tone formic acid (80 19 1). Plate was viewed under UV light. Equal concentrations of each sample were applied. Key y, yellow fluorescence b, blue fluorescence ------------------------, intense spots ---, less intense spots.

Figure D1.6.5 Sequential latroscan TLC-FID profiles of the lipid classes extracted from the dorsal white muscle of Atlantic salmon. I, II, and III represent partial chromatograms from the three-stage development of total lipids on aChromarod Sill. The solvent systems were (I) 80 14 1 0.2 (v/v/v/v) hexane/chloroform/isopropanol/formic acid for 55 min (II) acetone for 15 min and (III) 70 30 3 (v/v/v) chloroform/methanol/water for 60 min.

Method. The residue containing up to 1 pg of estrogen is dissolved in 0.9 ml of acetone. 0.1 ml of 0.01% DNS-C1 in acetone and 0.01 ml of 0.1 N sodium hydroxide are then added. The solutions are mixed and the reaction is kept at 50 °C for 30 min, cooled, diluted with 20 ml of benzene and extracted once with 5 ml of 0.1 N sodium hydroxide and twice with 5 ml of water before filtering through anhydrous sodium sulfate. The dry extract is evaporated to dryness under nitrogen. The residue is dissolved in a small volume of benzene for application of the sample to the TLC plates. The compounds are separated on plates of silica gel with chloroform-benzene—ethanol (18 2 1). The chromatogram is dried and observed under UV light. The minimum detectable quantities are 5—10 ng per spot. 

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