Metabolite ether extractability

To determine simultaneously the parent compounds and the metabolites of ethoben-zanid and clomeprop, each parent compound is extracted with n-hexane from the water sample, and the metabolites are extracted with diethyl ether after acidification of the remaining aqueous layer. 

Diphenyl ether herbicides are generally extracted from 10 to 50 g of air-dried soil with an organic solvent such as acetone, methanol and benzene by sonication, mechanical shaking or Soxhlet extraction. If necessary, the extracts are then cleaned by column chromatography or SPE. The extract is evaporated completely to dryness and the residue is dissolved in an appropriate volume of the solvent for GC analysis. The reduced amine metabolites are extracted under alkaline conditions. 

Studies directly examining the metabolism of organophosphate ester hydraulic fluids in animals are limited. One study identified metabolites in ether extracts of bile obtained from rabbits given single,... 

Metabolite I Rf Values II III IV % of ether extracts pet. ether methanol... 

The determination of 17-ketosteroids is most often determined in the clinical laboratory by the Zimmerman reaction, in which the ether-extracted material is allowed to react with m-nitroaniline to yield a colored product. Thus, any compound with the 17-keto basic structure such as reserpine, morphine, ascorbic acid, or their metabolites will interfere. The Porter-Silber reaction used in the determination of 17,21-dihydroxysteroids is also not specific, and the reaction requires a di-hydroxyacetone side chain. Paraldehyde, chloral hydrate, meprobromate, and potassium iodide have been found to interfere, and patients should be maintained free of these drugs for 24-48 hours before the urine collection (Bll). 

Cyclosporin A is slowly but extensively metabolized. The biotransformation pathway and the pattern of the generated metabolites are similar in humans and animals. Approximately 17 single metabolites have been detected so far, all of which are present in considerably lower plasma concentration than cyclosporin A itself [46]. Eleven ether-extractable compounds have been isolated from urine of dog and man and from rat bile and faeces using preparative HPLC and thin-layer chromatography [43]. Structural assignments for these... 

Danjiami acaride and metabolites Acid-base reflux petroleum ether extraction Derivatisation with heptafluorobu-tyranilide, then gas chromatography with mass spectrophotometric detection [532]... 

Figure 12. Effect of pH on ether extractability of h -THC in vivo metabolites from unhydrolyzed Rhesus urine...

The 215nm chromatograms of the pre- and post-drug Eli ether extracts (see Figure 1) equivalent to 2.5mg creatinine are shown in Figure 5. The Eli extract is of interest because of recent work by Greene (this volume) in which the ratio of bound to unbound urinary A9-THC-11 -oic acid, the major known THC metabolite in humans, was proposed to be a function of time after dose. As described in the experimental section, this acid partitions into the Eli fraction. 

The chromatograms of the E-III fraction which should contain the more polar acid metabolites, had too much interference from endogenous substances to allow cannabinoid detection. A comparison of the endogenous matrix levels of the hexane and ether extracts, expressed in terms of relative 215nm absorbance area in the cannabinoid elution region, is given in Table 3. 

The hydrolysis of steroid hydrogen sulphates, important to biochemists in view of the excretion of many steroid hormone metabolites as water soluble salts of hydrogen sulphates, has been studied in some detail [20,21]. It had been known for some years that ether extraction of the steroid hydrogen sulphate from acidified solutions is accompanied by hydrolysis of the sulphate in the ether phase, with liberation of the steroid alcohol. This hydrolysis was shown to follow first-order kinetics, but to be dependent in a remarkable way on the solvent. Ethers are the most effective solvents, followed by others of low polarity including benzene, esters and ketones, while water and alcohols have a strong retarding effect on hydrolysis. Neither acids nor bases produce significant catalysis, and the presence of did not result in incorporation of isotopic... 

Samples of the day 0 and day 10 homogenates were extracted and partitioned as shown schematically in Fig. 10.2. The petroleum ether and Sep-Pak acetonitrile fractions were analysed by HPLC (Fig. 10.3). The HPLC analyses showed a similar metabolite profile, with a lower percentage of PBO in the day 10 sample (24.4 of TRR) than in the day 0 sample (49-3% of TRR). The HPLC profile of the petroleum ether extracts showed that the predominant radioactivity extracted into the petroleum ether was parent compound (6.3 ppm for day 10). Numerous metabolites were observed in (he HPLC profile of the Sep-Pak... 

Ether-extracted freeze-dried kidney tissue contained the o-quinone metabolite of NDGA, seen as red-brown granules. It was also seen as yellowbrown material in histiocytes, degenerating proximal tubular epithelium, small acellular casts, and occasionally in the cells lining the cysts and in the lumen of the proximal convoluted tubules. No free NDGA was found in the rat kidneys (Goodman et al., 1970). 

This example of the recovery of a drug and its metabolites is important because it illustrates electron-capture detection. The drug studied is 7-chloro-l,3-dihydro-5-(2 -chlorophenyl)-2/f-l,4-benzodiazepin-2-one. In this study, the intent was to recover the intact drug and to recover and identify its metabolites in blood and urine. Figure 22.16 shows a typical chromatogram of a diethyl-ether extract of blood. The detection limit for the drug was 0.002 /Ag/ml of blood the very low levels of the drug... 

Early in the investigations the bulbs were stored in ethanol and were macerated and extracted with mixtures of ethanol containing increasing amounts of water. After filtration over hyflo super cel or celite and concentration in vacuo the different metabolites were extracted subsequently with petroleum ether (b. p. 50—70°), diethyl ether, chloroform, and chloroform-methanol (2 1). Emulsions, frequently occurring with petroleum ether, are prevented by careful stirring or addition of a... 

S. bottwpensis SY-2-1 biotransformed 1,8-cineole (122) stereochemically to (+)-2a-hydroj -l,8-cineole (125b) as the major product and (+)-3a-hydroxy-l,8-cineole (123b) as the minor product. Recovery ratio of 1,8-cineole metabolites as ether extract was ca. 30% in S. bottwpensis SY-2-1 (Noma and Nishimura, 1980, 1981) (Figure 19.135). 

The urine was adjusted to pH 4.6 with acetate buffer and incubated with p-glucuronidase-arylsufa-tase (3 mL/100 mL of fresh urine) at 37°C for 48 h, followed by continuous ether extraction for 48 h. The ether extracts were washed with 5% NaHCOj and 5% NaOH to remove the acidic and phenolic components, respectively. The ether extract was dried over MgS04, followed by evaporation of the solvent to give the neutral crude metabolites (Ishida et al., 1981). 

The neutral and acidic metabolites in cerebrospinal fluid were examined using gas-liquid chromatography, by Waterbury and Pearce (1972). These authors, using ethyl acetate and diethyl ether extraction and methyl ester, trimethylsilyl ether derivatives, observed citric, homovanillic, 3,4-dihydroxyphenylacetic, palmitic, stearic and 5-hydroxyindoleacetic acids, with palmitic acid predominating. No quantitative levels were recorded. 

Drugs and metabolites can be extracted from cultures and urine by adding 2 drops of concentrated HCI to 1 ml of urine for a pH of 1-2. Extract with three 1-ml volumes of diethyl ether (top layer) or methylene chloride (bottom layer). Combine extractions and evaporate with clean, dry nitrogen. Adjust to a pH of 8-10 by adding 250 /zl of 60% KOH to 1 ml of urine. Extract... 

The residue of the acetonitrile extract described above is dissolved in 5 mL of n-hexane and applied to a silica cartridge. Naproanilide and its metabolite are eluted with 10 mL of n-hexane-diethyl ether-acetic acid (85 15 1, v/v/v) after washing the cartridge with 5mL of n-hexane-diethyl ether-acetic acid (95 5 1, v/v/v). When using a Florisil column (10-g), naproanilide is eluted with 100 mL of diethyl ether-n-hexane (1 1, v/v) after washing the Florisil column with 100 mL of diethyl ether-n-hexane... 

Propanil and its metabolite in the n-hexane phase of the soil extract derived from Section 3.2.2(2) are passed through a Florisil column (previously activated at 300 °C overnight and deactivated with 2% water 2 g). Propanil residues are eluted with 20 mL of diethyl ether-n-hexane (1 1, v/v). 

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