Plasma butanol extraction

I. Thin-layer chromatography Mangalan et al. [53] used of an HPTLC method for the detection and determination of omeprazole in plasma levels. Plasma was extracted three times with dichloromethane at pH 6.5-7 and the combined extracts were evaporated to dryness at 60 °C. The residue was dissolved in dichloromethane and the solution was analyzed by TLC on aluminium-packed plates precoated with Silica gel 60 F254 with the upper organic layer of butanol-ammonium hydroxide-water (14 1 15) as mobile phase. The spots were observed by fluorescence quenching under UV light illumination at 280 nm the total area of each... 

Early paper chromatographic studies on plasma cobalamin extracts used Whatman 2 paper with s c-butanol-acetic acid-water (100 3 50) as the mobile phase (Lindstrand and Stahlberg, 1963). More recent studies on cobalamin separations have used silica and cellulose TLC. For instance, Firth et al. (1968) separated a large number of organocobalamins by cellulose TLC with four different solvent systems. Lindemans and Abels (1985) provided tabular data on TLC of vitamin B derivatives on cellulose. 

A first approach to the identification of blood thyroxine has been its separation by isotopic dilution from n-butanol extracts of plasma (60). Definite proof for the presence of the thyroxine has been obtained by paper radiochromatography (solvent, collidine-water-ammonia) of plasma extracts prepared from rat s blood 48 hours after injection of labeled iodides. A radioactive spot (autography) having exactly the same Rf value as that of the carrier Tx (30 /ig.) colored by ninhydrin has been revealed in these... 

The metabolism of Tx and TRITh can be studied only by injection of radioactive substrates labeled in different positions (see Section III). After injection into mice of labeled Tx, which has been isolated from plasma of rats treated with Nal (14), n-butanol extracts of tissues have... 

Acylcarnitine analysis of dried blood or bile spots is very similar to the analysis of plasma. A small disk (diameter typically 5 mm or less) is punched out of the blood spot and the acylcarnitines extracted by the addition of methanol and known concentrations of isotopically labeled acylcarnitines, which function as internal standards. The extract is dried under a stream of nitrogen, and derivatized by the addition of either n-butanol HC1 or n-methanol HC1. The acylcarnitines are measured as their butyl or methyl esters by MS-MS. The concentrations of the analytes are established by computerized comparison of ion intensities of these analytes to that of the internal standards. 

Couchman et al. developed a method for simultaneous analysis of amisulpride, metamphetamine, and amphetamine in plasma by HPLC-MS/MS. To the sample (200 pi), ISTDs solution and NaOH solution were added to the extraction solvent (butyl acetate-butanol, 9 1). HPLC separation was performed by strong cation-exchange. The use of methanol as eluent improved sensitivity for analytes due to more efficient in-source desolvation when compared with aqueous eluents [99],... 

Jacob et al. developed a method for the determination of nicotine and cotinine in plasma and urine samples using structural analogues for both compounds as internal standards, N-ethylnomicotine for nicotine and N-(2-methoxyethyl)-nomicotine for cotinine. Glass columns (1.8 m for nicotine and 1.2 m for cotinine, by 2 mm I.D.) packed with 2 % Carbowax 20 M + 2 % KOH on Gas Chrom P 100-120 mesh or 3 % SP-2250 DB on Supelcoport 100-120 mesh were used, and column temperatures 145°C for nicotine and 210°C for cotinine. The alkaloids were extracted from the sample with diethyl ether (nicotine) or butanol (cotinine) after addition of NaOH, back extraction into acid and re-extraction into diethyl ether (nicotine) or methyl-chloride (cotinine). Linearity in the range of 0-100 ng/ml nicotine and 0-1000 ng/ml cotinine was achieved by means of a nitrogen-detector. 

Sample preparation 1 mL Plasma + 50 (jlL 2 M KOH + 100 jiL pH 12.2 glycine buffer + 5 mg NaCl, vortex, add 8 mL dichloromethane 1-butanol 95 5, extract. Remove 7 mL of the organic layer and evaporate it to dryness under a stream of nitrogen, reconstitute the residue in 1 mL 1 mg/mL 4-dimethylaminopjn idine in dioxane, add 500 jtL 20% phosgene in toluene, vortex, heat at 70° for 1 h, heat at 40° overnight. Evaporate to dryness under a stream of nitrogen, reconstitute the residue in 50 pL mobile phase, inject a 20 pL aliquot. 

Sample preparation 1 mL Plasma + 100 pL tolmetin solution + 500 pL pH 1.8 phosphate buffer, extract with 1-butanol/MTBE. Remove the organic layer and add it to 500 pL pH... 

Significant reductions in plasma glucose levels were observed in diabetic rats orally administered aqueous, eth-anolic, and hexanic extracts of cow s foot daily for 7 days (Lino et al. 2004). Similarly, a reduction in serum and urinary glucose levels was observed in diabetic rats provided a decoction of cow s foot as the sole source of drinking water (150 g leaf/1 water mean daily dose of 3.52 ml/kg) (Pepato et al. 2002). A significant reduction of blood glucose levels was observed in healthy and in diabetic rats orally administered 500 to 600 mg/kg of the n-butanol fraction of cow s foot (Silva et al. 2002). 

There has been much speculation in the past on the nature of the circulating thyroid hormone whether it was a simple amino acid, a peptide or polypeptide of thyroxine, or thyroglobulin itself. In 1948 Taurog and Chaikoff produced a considerable amount of evidence that the plasma hormone was indeed thyroxine. Labeled plasma iodine behaved chemically in a manner identical with that of thyroxine added to plasma it was nondialyzable it was precipitated with plasma proteins with zinc hydroxide it was extractable with butanol, and it could be fractionated with carrier thyroxine by its partition between immiscible solvents. This work received confirmation from Laidlaw (1949), and it then became generally accepted that thyroxine alone was the circulating hormone. 

Also, previous to the MLC separation, chlorthalidone was extracted into diethyl ether-2-propanol from plasma, using xipamide as an internal standard [12], catecholamines were extracted from urine through alumina columns and eluted with 0.5 M perchloric acid [44] and clenbuterol in urine was eluted from a cation-exchange sorbent with the same solvent used as mobile phase (0.1 M SDS-12% 1-butanol) [45]. 

The first practical method developed for the simultaneous determination of heroin and its metabolites utilized a complex multistep liquid-liquid extraction scheme. Under mild alkaline conditions, analytes from plasma are isolated with a mixture of toluene-butanol. The analytes are back-extracted into dilute sulfuric acid and the acid phase is washed with n-hexane. After adjusting the pH, the aqueous phase is extracted with toluene-butanol. Following separation and evaporation of the organic phase, the extract is reconstituted in methanol and analyzed by LC. 

Use of serial GCEs [electrode 1 (A) —0.8 V, (B) 0 V electrode 2 (A) and (B) +0.85 V V5 Ag/AgCl] to facilitate the ED of fluphenazine sulfoxide. Column 300x3.9 (i.d.) mm x Bondpak ODS-silica 10 m. Eluent methanol-formic acid (0.15 mol containing dibutylamine (10 mmol L j, pH3.2 (50 + 50) Flow-rate 2.0 mL min Injection lyophilised 3-methyl-1-butanol (isopenta-nol) extract of plasma containing added fluphenazine, fluphenazine sulfoxide and other fluphenazine metabolites (amounts and injection volume not given) Peaks 1 = fluphenazine sulfoxide, 2 = 7-hydroxyfluphenazine, 3 = 8-hydroxyfluphenazine, 4 = fluphenazine, 5 = fluphenazine N-oxide. 

Alternatively, it is possible to inject the solvent extract directly for HPLC analysis. For good quantitation this method requires an internal standard or very careful measurement of liquid volumes. McClean et al. (69) and Nierenberg and Lester (70) used acetonitrile to denature plasma proteins and then solubilized retinol with ethyl acetate 1-butanol (1 1) for direct injection Siddiqui et al. precipitated proteins from serum by addition of acetonitrile, centrifuged, and then injected the supernatant (71). Retinoids and carotenoids can be efficiently extracted from one volume of serum or plasma with three volumes of 2-propanol dichloromethane (2 1) followed by centrifugation an aliquot can be directly analyzed by HPLC (72,73). The risks of sample loss and degradation during processing can thus be avoided. 

Plasma should be extracted once with 3 volumes, and then twice with equal volumes of n-butanol saturated with 0.1 N HCl in 40-ml. centrifuge tubes (round bottom, thin neck). The butanol phases are separated by centrifugation and collected with a pipet. After drying under vacuum (<45°), the residue is dissolved in 0.2 ml. of n-butanol. The total radioactivity of the final solution is considerably lower than that of gland extracts 50 to 200 m1- must be used to obtain sufficient radioactivity. Under these conditions the fats and pigments present in the plasma extracts can interfere with the chromatography, and it is, therefore, preferable to use a sample having the smallest volume with moderate radioactivity. 

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