Ethyl acetate 4-hydroxyphenylacetic acid

Rump [17] has described a cellulose thin layer method for the detection of phenolic acids such as iw-hydroxybenzoic acid, iw-hydroxyphenylacetic acid and m-hydroxyphenylpropionic acid, in water samples suspected to be contaminated with liquid manure. The phenolic acid is extracted with ethyl acetate from a volume of acidified sample equalling lmg of oxygen consumed (measured with potassium permanganate). The ethyl acetate is evaporated and the residue dissolved in ethanol. After spotting of a lpm aliquot on a cellulose plate the chromatogram is developed by capillary ascent with the solvent n-propanol-w-butanol-25% NH3-water (4 4 1 1 by vol). The solvent front is allowed to advance 10cm. The air-dried plate is sprayed with a diazotised p-nitroanilinc reagent to make the phenolic acids visible. 

Fig. 7.2 Chromatogram of acidic metabolites extracted from the urine of a normal child using DEAE-Sephadex and re-extraction with solvents after ethoxime formation and freeze-drying by reconstitution in water, acidification with hydrochloric acid, saturation with sodium chloride, and solvent extraction with diethyl ether (three times) and ethyl acetate (three times), evaporation of the solvents from the combined extracts using dry nitrogen and trimethylsilylation using the minimum quantity of BSTFA. Separated on 10 per cent OV-101 on HP Chromosorb W (80-100 mesh) by temperature programming from 110°C to 285°C at 4°C min with an initial 5 min isothermal delay. Peak identifications are 1, phenol plus lactate 2, glycollate 3, cresol 4, 3-hydroxyisovalerate 5, benzoate 6, phosphate 7, succinate 8, 3-methyladipate 9, 3-hydroxy-3-methyl-glutarate 10, 4-hydroxyphenylacetate 11, homovanillate plus some aconitate 12, hippurate 13, citrate 14, vanilmandelate 15, n-tetracosane (standard) 16, n-hexacosane (standard).

Ward et al. (1976) examined the free organic acids in unstimulated human saliva using open tubular capillary gas chromatography columns and GC-MS using ether and ethyl acetate extraction methods and trimethylsilyl derivatives. They identified lactic, 2-hydroxyisocaproic, succinic, phenyl-lactic, phenyl-acetic, 4-hydroxyphenylacetic, 4-hydroxyphenylpropionic, myristic, palmitic, oleic and stearic acids. 

Fig. 11.2 Total ion current chromatogram (Varian MAT 44 GC-MS) of organic acids extracted using ethyl acetate and diethyl ether from the urine of a patient with propionic acidaemia and separated as their trimethylsilyl derivatives on a 25 m SE-54 WCOT capillary column using temperature programming from 70°C to 220°C at 4 C min Peak identifications are 1, lactate 2, 3-hydroxypropionate 3, 3-hydroxybutyrate 4, 2-methyl-3-hydroxybutyrate 5, 3-hydroxyisovalerate 6, 3-hydroxy- -valerate 7, aceto-acetate 8 and 9, 2-methyl-3-hydroxyvalerate 10, 3-oxovalerate 11, 2-methyl-3-oxo-valerate (isomer 1) 12,2-methylacetoacetate 13,2-methyl-3-oxovalerate (isomer 2) 14 propionylglycine 15, glutarate 16, adipate 17, 5-hydroxymethyl-2-furoate 18, 2-hydroxyglutarate 19,3-hydroxy-3-methylglutarate 20,4-hydroxyphenylacetate 21 and 22, methylcitrate 23,4-hydroxyphenyl-lactate 24, palmitate. (Redrawn with modifications from Truscott et al., 1979)...

Fig. 14.5 Chromatogram of organic acids extracted using diethyl ether and ethyl acetate from the urine of a patient with suberylglycinuria and separated as their methyl derivatives (diazomethane) on 3 per cent SE-30 on Chromosorb W (DMCS, 80-100 mesh) using temperature programming from 80°C to 250°C at 6°C min Peak identifications are 1, 3-hydroxybutyrate 2, adipate 3, 3-methyladipate 4, pimelate (heptanedioate) 5, octenedioate 6, suberate (octanedioate) 7, hexanoylglycine plus 4-hydroxyphenylacetate 8, azeleate (nonanedioate) 9, decenedioate 10, sebacate (decanedioate) 11, hippurate 12, unknown, 13, suberylglycine. (Redrawn with modifications from Truscott et al., 1979)...

Fig. 16.2 Chromatogram of organic acids extracted using ethyl acetate and diethyl ether from the urine of a patient with o-glyceric aciduria (Brandt et al, 1976) and separated as their trimethylsiiyl derivatives on 3 per cent OV-1. Peak identifications are 1, glycollate plus lactate 2, urea 3, glycerate (d) 4, 4-hydroxyphenylacetate. (Redrawn with modifications from Brandt et al, 1976)...

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