Assay of urinary 4-hdyroxy-3-methoxymandelic (vanillylmandelic) acid by liquid chromatography with electrochemical detection.

Abstract We describe a method for the assay of urinary 4-hydroxy-3-methoxyphenylacetic acid (homovanillic acid), based on its separation on a microparticulate reversed-phase column and direct electrochemical detection. Patients with neuroblastoma, pheochromocytoma, and Parkinson's disease have increased amounts of this compound in their urine.

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Determination of glutamate and aspartate in microdialysis samples by reversed-phase column liquid chromatography with fluorescence and electrochemical detection

Journal of Chromatography B Biomedical Sciences and Applications ◽

10.1016/s0378-4347(97)00677-4 ◽

1998 ◽

Vol 708 (1-2) ◽

pp. 27-38 ◽

Cited By ~ 40

Author(s):

Jan Kehr

Keyword(s):

Column Liquid Chromatography ◽

Liquid Chromatography ◽

Electrochemical Detection ◽

Reversed Phase ◽

Phase Column ◽

Reversed Phase Column

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Liquid-chromatographic assay of urinary 5-hydroxy-3-indoleacetic acid, with electrochemical detection.

Clinical Chemistry ◽

10.1093/clinchem/26.7.907 ◽

1980 ◽

Vol 26 (7) ◽

pp. 907-909 ◽

Cited By ~ 22

Author(s):

Z K Shihabi ◽

J Scaro

Keyword(s):

High Performance Liquid Chromatography ◽

Liquid Chromatography ◽

Electrochemical Detection ◽

High Performance ◽

Indoleacetic Acid ◽

Reversed Phase ◽

Solvent Mixtures ◽

Liquid Chromatographic ◽

Phase Column ◽

Reversed Phase Column

Abstract After extraction with two organic solvent mixtures, urinary 5-hydroxy-3-indoleacetic acid can be assayed by "high-performance" liquid chromatography on a reversed-phase column, with electrochemical detection. Compared to the nitrosonaphthol method (J. Biol. Chem. 216: 499, 1955), this method is more specific for detection of patients with carcinoid tumors.

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Urinary 3-methoxy-4-hydroxymandelic acid as measured by liquid chromatography, with on-line post-column reaction.

Clinical Chemistry ◽

10.1093/clinchem/25.7.1234 ◽

1979 ◽

Vol 25 (7) ◽

pp. 1234-1238 ◽

Cited By ~ 7

Author(s):

J G Flood ◽

M Granger ◽

R B McComb

Keyword(s):

Liquid Chromatography ◽

Phosphate Buffer ◽

Reversed Phase ◽

Urine Samples ◽

Vanillylmandelic Acid ◽

Control Data ◽

On Line ◽

Phase Column ◽

Reversed Phase Column

Abstract We describe a method for measurement of 3-methoxy-4-hydroxymandelic acid (vanillylmandelic acid, VMA) in urine. After the pH of the urine is adjusted to 2.7 and the sample is filtered, exactly 15 microL is injected onto a C-18 reversed-phase column. VMA is eluted from the column with 10 mmol/L phosphate buffer, pH 2.7, containing 30 mL of acetonitrile per liter. The eluate stream is combined with alkaline periodate and then passed through a 60 degrees C water bath. The VMA is completely oxidized to vanillin, which is detected and quantitiated by its absorbance at 360 nm. No deterioration of the column was noted after 167 such injections of urine samples. Long-term control data indicate a CV of 12 and 10% at VMA concentrations of 1.5 and 5.8 mg/L, respectively. Although results correlate well (r = 0.976) with those by the method of Pisano et al. [Clin. Chim. Acta 7, 285 (1962)], they average 10% lower. Of 20 compounds tested, only methyl dopa interfered with the procedure as described.

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Liquid-chromatographic assay of urinary 5-hydroxy-3-indoleacetic acid, with electrochemical detection.

Clinical Chemistry ◽

10.1093/clinchem/26.7.0907 ◽

1980 ◽

Vol 26 (7) ◽

pp. 907-909

Author(s):

Z K Shihabi ◽

J Scaro

Keyword(s):

High Performance Liquid Chromatography ◽

Liquid Chromatography ◽

Electrochemical Detection ◽

High Performance ◽

Indoleacetic Acid ◽

Reversed Phase ◽

Solvent Mixtures ◽

Liquid Chromatographic ◽

Phase Column ◽

Reversed Phase Column

Abstract After extraction with two organic solvent mixtures, urinary 5-hydroxy-3-indoleacetic acid can be assayed by "high-performance" liquid chromatography on a reversed-phase column, with electrochemical detection. Compared to the nitrosonaphthol method (J. Biol. Chem. 216: 499, 1955), this method is more specific for detection of patients with carcinoid tumors.

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Determination of urinary vanillylmandelic acid by liquid chromatography with electrochemical detection.

Clinical Chemistry ◽

10.1093/clinchem/29.5.878 ◽

1983 ◽

Vol 29 (5) ◽

pp. 878-881 ◽

Cited By ~ 14

Author(s):

P Moleman ◽

J J Borstrok

Keyword(s):

Liquid Chromatography ◽

Ethyl Acetate ◽

Electrochemical Detection ◽

High Performance ◽

Ethyl Acetate Extract ◽

Reversed Phase ◽

Vanillylmandelic Acid ◽

Improved Method ◽

Phase Column

Abstract We describe an improved method for the assay of urinary vanillylmandelic acid by "high-performance" liquid chromatography, with electrochemical detection. A 1-mL aliquot of urine is acidified and extracted with ethyl acetate, then the ethyl acetate extract is extracted with phosphate buffer, pH 8.5. An acidified aliquot of the phosphate extract is injected into a reversed-phase column and vanillylmandelic acid is detected electrochemically. The between-day CV is 5-6% for concentrations ranging from 10 to 75 mumol/L. We also discuss the critical steps for extraction and calibration.

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4-Nitrophenol in 4-nitrophenyl phosphate, a substrate for alkaline phosphatase, as measured by paired-ion high-performance liquid chromatography.

Clinical Chemistry ◽

10.1093/clinchem/23.12.2288 ◽

1977 ◽

Vol 23 (12) ◽

pp. 2288-2291 ◽

Cited By ~ 4

Author(s):

P H Culbreth ◽

I W Duncan ◽

C A Burtis

Keyword(s):

Alkaline Phosphatase ◽

High Performance Liquid Chromatography ◽

Liquid Chromatography ◽

Flow Rate ◽

Mobile Phase ◽

High Performance ◽

Reversed Phase ◽

Nitrophenyl Phosphate ◽

Phase Column ◽

Reversed Phase Column

Abstract We used paired-ion high-performance liquid chromatography to determine the 4-nitrophenol content of 4-nitrophenyl phosphate, a substrate for alkaline phosphatase analysis. This was done on a reversed-phase column with a mobile phase of methanol/water, 45/55 by vol, containing 3 ml of tetrabutylammonium phosphate reagent per 200 ml of solvent. At a flow rate of 1 ml/min, 4-nitrophenol was eluted at 9 min and monitored at 404 nm; 4-nitrophenyl phosphate was eluted at 5 min and could be monitored at 311 nm. Samples of 4-nitrophenyl phosphate obtained from several sources contained 0.3 to 7.8 mole of 4-nitrophenol per mole of 4-nitrophenyl phosphate.

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