Diagnosis of neural crest tumors by reversed-phase high-performance liquid chromatographic determination of urinary catecholamine metabolites

Development of an enzyme-linked immunosorbent assay with monoclonal antibody for quantification of homovanillic in human urine samples

A monoclonal antibody to homovanillic acid (HVA) was prepared by synthesis of a HVA-protein conjugate (HVA-ovalbumin) as an immunogen, immunization of mice, and the subsequent hybridization technique. Monoclonal antibodies were screened on the basis of sensitivity, specificity, and accuracy. An indirect ELISA was developed for quantification of HVA in human urine. The assay was characterized and shown to have high specificity, with cross-reactivities to vanillylmandelic acid and normetanephrine at 0.18% and <0.1%, respectively. The assay coefficients of variation were <10% within the working range of 0.5–40 mg/L. Initial results from testing urine samples of patients with neuroblastoma and other diseases were validated by HPLC, suggesting that this ELISA method is a reliable and convenient system for quantification of HVA in urine and can be used in the mass screening of neuroblastoma in infants.

High-performance liquid chromatographic analysis with electrochemical detection of biogenic amines using microbore columns

High-performance liquid chromatography with electrochemical detection (HPLC-ED) is a popular method for measuring biogenic amines, owing to its simplicity, versatility, sensitivity, and specificity. Recent developments in microbore column HPLC-ED have been facilitated by miniaturization of solvent delivery, column packing, sample injection and micro-flow cell construction. The aim of this paper is to present an overview of recent developments in microbore column HPLC-ED, in terms of advantages and limitations. This paper covers the recent advancements and important factors of HPLC-ED analysis of biogenic amines using microbore columns. Particular emphasis is placed on applying this technique to microdialysis, for which great sensitivity is required. Its potential in future biomedical applications is also discussed.

High-performance liquid chromatographic determination of catecholamine metabolites and 5-hydroxyindoleacetic acid in human urine using a mixed-mode column and an eight-channel electrode electrochemical detector

An HPLC system for the simultaneous determination of acidic catecholamine metabolites, related compounds and 5-hydroxyindoleacetic acid (5-HIAA) in human urine was developed. A mixed-mode (C18/anion-exchange) column with isocratic elution using citrate buffer and an eight-channel electrochemical detector were used. Vanilmandelic acid (VMA), 3,4-dihydroxyphenylacetic acid (DOPAC), 4-hydroxy-3-methoxyphenyllactic acid (vanillactic acid, VLA), homovanillic acid (HVA), vanillic acid (VA) and 5-HIAA in urine were determined simultaneously. Detection limits and inter (n = 5) and intra-assay (n = 5) coefficients of variation were satisfactory. The mean of analytical recoveries (n = 3, +/- C.V. (%)) were between 97 +/- 3.2 (VMA) and 105 +/- 4.8 (VA). Correlations between the analytical results for VMA, HVA and 5-HIAA obtained by an established method and the present method were satisfactory. The mean +/- 2 S.D. of the excretion rates of VMA, DOPAC, VLA, HVA, 5-HIAA and VA in urine from healthy adult volunteers were 0.61-4.36, 0.13-1.02, 0-0.35, 0.67-6.55, 0.50-5.14 and 0-0.55 mg/g creatinine, respectively.

The metabolism of noradrenaline in the sheep and the effect of dry matter intake upon the production of a metabolite, urinary vanillylmandelic acid

1. The metabolism of noradrenaline was investigated in the sheep using 3H-noradrenaline injected subcutaneously or intravenously. 2. Analysis of urine collected over 24 hr showed that the bulk of 3H-noradrenaline was rapidly degraded and excreted via the urine. The principle metabolite was the conjugated amine as well as monohydroxy phenyl glycol and vanillylmandelic acid (VMA) previously reported for the rat. 3. Urinary VMA from lambs of two breeds noted for differences in fat (Southdown and Suffolk) increased curvilinearly with dry matter intake and there was a significant breed difference in regression with intake. 4. It is feasible that differences in noradrenaline production could contribute to differences in body composition between breeds.

High-performance liquid chromatographic determination of catecholamines and their precursor and metabolites in human urine and plasma by postcolumn derivatization involving chemical oxidation followed by fluorescence reaction

A high-performance liquid chromatographic method for the determination of catecholamines and their precursor and metabolites [amino compounds (norepinephrine, epinephrine, dopamine, normetanephrine, metanephrine, 3-methoxytyramine, and L-DOPA), acidic compounds (3,4-dihydroxyphenylacetic acid, vanillyl-mandelic acid, and homovanillic acid), and alcoholic compound [4-hydroxy-3-methoxyphenyl)ethylene glycol)] in human urine and plasma. Urine and plasma samples deproteinized with perchloric acid in the presence of isoproterenol and 3,4-dihydroxyphenylpropanoic acid (internal standards) are fractionated by solid-phase extraction on a strong cation-exchange resin cartridge (Toyopak IC-SP S) into two fractions (amine fraction and acid-alcohol fraction). The compounds in each fraction are separated by an ion-pair reversed-phase chromatography on a TSK gel ODS-80TM with isocratic elution and on-line derivatized by periodate oxidation followed by a fluorescence reaction using meso-1,2-diphenylethylenediamine. The detection limits (S/N = 5) vary from 0.5 to 95 pmol/ml, depending on the compounds.

Recent developments in the diagnosis and treatment of pheochromocytoma

The investigation and management of pheochromocytoma have been of special interest at the Mayo Clinic since 1926, when Dr. C. H. Mayo successfully removed an adrenal tumor. Recent clinical developments include the detection of asymptomatic paroxysms of hypertension by 24-hour ambulatory monitoring, detailed characterization of catecholamine cardiomyopathy by echocardiography, and further experience with Carney's triad and other polyglandular and multiple neoplasia syndromes associated with pheochromocytoma. Refinement in interpretation of catecholamine measurements and the development of radionuclide scanning with m-[131I]iodobenzylguanidine, computed tomography, and magnetic resonance imaging have greatly enhanced our diagnostic acumen. Developments in antihypertensive drug therapy and chemotherapy have improved our management of cathecholamine hypersecretion and tumor growth, respectively, in inoperable patients and in the preparation of patients for anesthesia and surgical treatment. Flow cytometry to detect abnormal DNA histograms may prove particularly useful in predicting the malignant nature of the tumors.

Automated analysis of urinary 3-methoxy-4-hydroxy-mandelic acid using ion-pair chromatography and fluorimetric detection

A new rapid high-performance liquid chromatographic method, without urine sample pre-treatment and based on isocratic ion-pair elution, fluorimetric detection and column-switching, has been developed for the determination of vanillylmandelic acid. The sensitivity was 0.1 mg/l, and the linearity was excellent in the concentration range tested. For all endogenous substances as well as for all the drugs tested no interferences were observed. Typical concentrations were in the range 0.3-5.5 mg of vanillylmandelic acid per day, depending on the age of subject under investigation.

Catecholamines and their metabolites

The research on biosynthesis, physiology, pharmacology, regulation and degradation of catecholamines has continuously increased for more than 50 years. This is not unexpected because of the fact that catecholamines are involved in so many life processes such as nerve conduction, blood circulation and hormone regulations in health and disease. This demands that methods for their determination should be improved, and in fact during the years a number of analytical methods have been published. About 20 years ago radioenzyme techniques with thin-layer chromatographic (TLC) separation of radiolabelled catecholamine derivatives were developed which greatly contributed to our knowledge of physiological concentrations of catecholamines in biological media, particularly in plasma and brain. Radioimmune methods were successful for analysis of a number of analytes, but for catecholamines radioimmunoassays developed slowly. We believe that the greatest potential for radioimmunochemical methods lies in their ability to localize catecholamines and metabolites at the cellular and subcellular levels. With the advent of gas chromatographic-mass spectrometric (GC-MS) and high-performance liquid chromatographic (HPLC) procedures analysis of catecholamines improved greatly., The equipment for GC-MS is expensive and requires technical skillfulness, but in experienced hands a lot of new biological data have emerged. An outstanding quality with GC-MS is that the method offers the ability to identify unknown compounds and is relatively free from interferences from extraneous compounds. In comparison with GC-MS, HPLC is versatile and has gained a widespread use. Applications for research in the catecholamine field are numerous. In general, the sensitivity and specificity are satisfactory with HPLC, but it should be borne in mind that a number of pitfalls can obscure the results. This involves both sample handling, clean-up and chromatographic procedures. At present, HPLC is the most expanding field in chromatographic determination of catecholamines and their metabolites. This is particularly the case for HPLC with electrochemical detection which has revolutionized our analytical potential in this field. These chromatographic procedures continue to develop. The prerequisites for further improved methods such as capillary zone electrophoresis and combined HPLC-MS are at hand and hopefully will soon come into more general use for analysis of catecholamines in biological samples.

High-performance liquid chromatography of biogenic amines and metabolites in brain, cerebrospinal fluid, urine and plasma

A method for high-performance liquid chromatographic separation and electrochemical detection of biogenic amines and metabolites in a variety of biological matrices is described. The method employs either homogenization, precipitation or dilution followed by direct injection of the samples and permits the chromatographic resolution of dopamine, norepinephrine, epinephrine, serotonin (5-HT), 3,4-dihydroxyphenylacetic acid (DOPAC), 5-hydroxyindoleacetic acid (5-HIAA) and homovanillic acid (HVA) in brain; 3-methoxy-4-hydroxyphenylglycol, DOPAC, 5-HIAA and HVA in cerebrospinal fluid; 5-HIAA, HVA and 5-HT in plasma; and 5-HIAA and HVA in urine. Alterations in chromatographic conditions, voltammetry and in vivo pharmacological manipulations are employed to verify the identity of the putative neurotransmitter and metabolite peaks in the biological samples.

A comparative study of five different methods for the determination of 3-methoxy-4-hydroxymandelic acid in urine

Five different methods for the determination of 3-methoxy-4-hydroxymandelic acid (vanilmandelic acid, VMA) in urine were compared: a GLC-FID catecholamine metabolite profiling method, an HPLC method with electrochemical detection, the method of Pisano et al. [1962) Clin. Chim. Acta 7, 285-291), a one dimensional paper chromatographic method with diazotized p-nitroaniline staining and the commercially available Bio-Rad VMA by Column Test. The comparison consisted of an imprecision study, a linearity check, a recovery study, a split sample comparison and an interference study. The best results of the imprecision study (n = 8) were found with the Bio-Rad and the HPLC method (within-run imprecision had a coefficient of variation (CV) of 5.1% and 1.4%; between-days CV of 5.9% and 6.0% respectively for values of 32.4 mumol/l and 24.5 mumol/l). The Pisano method had the poorest within-run CV (14.6%) and between-days CV (16.8%) for a value of 23.2 mumol/l. All methods showed good linearity. The mean recovery of the HPLC method was 101.3%; the mean recovery of the other four methods ranged from 93.9%-96.0%. The split sample comparison showed that the accuracy of the HPLC, the GLC and the Pisano method is comparable. The accuracy of the paper chromatographic method and the Bio-Rad method had a positive bias compared with the HPLC method. Especially the positive bias of the Bio-Rad method can be very large. The HPLC method was not influenced by the compounds tested in the interference study, whereas the GLC method in some cases only suffered from overloading problems. The Pisano and the Bio-Rad method were most influenced by the interfering compounds tested. We conclude that the HPLC and the GLC methods are superior to the other three VMA methods. From an analytical point of view HPLC is the method of choice for determining 3-methoxy-4-hydroxymandelic acid in urine.

Determination of norepinephrine and its metabolites released from rat vas deferens using high-performance liquid chromatography with electrochemical detection

We designed a rapid, simple and sensitive method for the determination of norepinephrine (NE) and its metabolites by reversed-phase high-performance liquid chromatography (HPLC) with electrochemical detection. NE, 3,4-dihydroxymandelic acid (DOMA), and 3,4-dihydroxyphenylglycol (DOPEG) were adsorbed on alumina and eluted with 0.2 N HCl. From the remaining solution, normetanephrine and 3-methoxy-4-hydroxyphenylglycol (MOPEG) were extracted with ethyl acetate in the presence of both borate buffer and K2HPO4. Vanillylmandelic acid was extracted with ethyl acetate after acidification of the solution with concentrated HCl. The combined ethyl acetate phase was evaporated and the residue was dissolved in 0.1 N HCl. A 50 mu1 aliquot of each eluate or solution was injected onto the HPLC. Detection limits ranged from 300 pg to 1 ng per initial sample. We used this method to determine substances in the medium following incubation of the rat vas deferens. Approximately 110 and 80 ng/g/10 min of DOPEG and MOPEG, respectively, were present under normal conditions. The electrical stimulation of tissues from the rat vas deferens led to increases in the levels of NE, DOPEG, DOMA and MOPEG. Normetanephrine and vanillylmandelic acid were not detected in the medium. This is probably the first documentation of the endogenous levels of NE and all its metabolites in medium containing tissue of the sympathetic nervous system.

Simultaneous determination of free 3-methoxy-4-hydroxymandelic acid and free 3-methoxy-4-hydroxyphenylethyleneglycol in plasma by liquid chromatography with electrochemical detection

A new assay method is described for the simultaneous determination of free 3-methoxy-4-hydroxymandelic acid and 3-methoxy-4-hydroxyphenylethyleneglycol in plasma utilizing separation and purification by Bio-Gel P-10 followed by high-performance liquid chromatography with electrochemical detection. This technique is sensitive and reliable, and offers an inexpensive and practical alternative to gas chromatographic--mass fragmentographic methods for the monitoring of plasma levels of these catecholamine metabolites in the study of selective metabolic pathways of endogenous norepinephrine originating in the peripheral and the central nervous systems.

Urinary 3-methoxy-4-hydroxyphenylglycol determination using reversed-phase chromatography with amperometric detection

A reversed-phase liquid chromatographic method with amperometric detection has been developed for the determination of urinary 3-methoxy-4-hydroxyphenylglycol. Before and after enzymatic deconjugation, it was purified by an extraction procedure and rapidly quantified under isocratic conditions. The 24-h excretion profile in normal human subjects (eight males and seven females) was determined; our results are consistent with those arrived at in a number of other studies. The present method is highly sensitive and selective; in addition, a good degree of precision is assured by use of 4-methoxy-3-hydroxyphenylglycol as internal standard.

Investigations of catecholamine metabolism using high-performance liquid chromatography: analytical methodology and clinical applications

High-performance liquid chromatography, particularly in its reversed-phase mode, coupled with electrochemical or fluorometric detection, is becoming increasingly popular as an analytical tool for metabolic profiling of substances of neurochemical interest, such as catecholamines and their metabolites. During the last decade, a continued effort has been made to improve and simplify the analytical methodology for routine use in clinical laboratories where this technique is tremendously needed. New developments in column technology, reliable detectors, simplified sample cleanup procedures, and particularly better understanding of the complex physicochemical phenomena underlying the operation of electrochemical detection, have resulted in a steady and encouraging progress. The purpose of this review was to describe the current analytical methodology and recent applications of HPLC in the field of catecholamine metabolism. Although this discussion is by no means detailed and complete, it, at least, hints at the impact of this technique on biochemical investigations and its future potential in clinical laboratories.

Analysis of urinary 3-methoxy-4-hydroxyphenylglycol by high-performance liquid chromatography and electrochemical detection

A high-performance liquid chromatographic method with electrochemical detection for the quantitation of total 3-methoxy-4-hydroxyphenylglycol (MHPG) in human urine is described. Existing methods for deconjugation and extraction have been optimized. The present method is simpler than existing methods with a high precision. Urinary MHPG is deconjugated enzymatically and subsequently extracted with ethyl acetate. The organic layer is extracted with acetic acid and a sample of the aqueous layer is injected into a reversed-phase column. In one run 90 samples can be processed. The critical parameters of deconjugation, extraction and chromatography are described. Data for reproducibility and selectivity are presented.

Simple high-performance liquid chromatographic method for the concurrent determination of the amine metabolites vanillylmandelic acid, 3-methoxy-4-hydroxyphenylglycol, 5-hydroxyindoleacetic acid, dihydroxyphenylacetic acid and homovanillic acid in urine using electrochemical detection

A simple method for the concurrent analysis of the noradrenaline metabolites vanillylmandelic acid and 3-methoxy-4-hydroxyphenylglycol, the dopamine metabolites dihydroxyphenylacetic acid and homovanillic acid, and the serotonin metabolite 5-hydroxyindoleacetic acid in human urine is described. Following organic extraction of the metabolites from acidified urine, they are separated by single-step gradient elution high-performance liquid chromatography on a reversed-phase column. Detection and quantification are achieved with an electrochemical detector using a carbon-paste electrode; samples can be injected at 40-min intervals. Optimisation of analytical parameters is described, and examples of the application of the method in the fields of clinical chemistry and clinical neuroscience are given. This provides a convenient method for the concurrent study of the metabolism of three major biogenic amines, and is readily adaptable for studies on cerebrospinal fluid and brain tissue.

Analysis of some tryptophan and phenylalanine metabolites in urine by a straight-phase high-performance liquid chromatographic technique

A high-performance liquid column chromatographic technique is reported for the analysis of some tryptophan and phenylalanine acid metabolites in the urine. An acidified and NaCl-saturated urine sample is loaded on to a C18-bonded silica microcolumn. After washing the microcolumn with clean and deionized water, the metabolites of interest are selectively extracted by successive elutions with organic solvents of variable polarity. Acids are eluted first and the neutral compounds with the next fraction. Basic compounds and other neutral substances of higher polarities were eliminated during the washing procedure. The chromatography was performed in the straight-phase isocratic elution mode utilizing 5-micrometers silica-gel columns loaded with a triethanolammonium perchlorate--perchloric acid aqueous solution. The separation achieved have permitted the application of the chromatographic technique to the analysis of urinary metabolites with acceptable accuracy.

Separation of 5-hydroxyindole-3-acetic acid and indole-3-acetic acid in urine by direct injection on a reversed-phase column containing a hydrogen-accepting stationary phase

The separation of 5-hydroxyindole-3-acetic acid and indole-3-acetic acid from urine is demonstrated. The urine is injected directly on a liquid chromatographic column which is coupled to a flow-through fluorescence detector or a UV detector. A hydrogen-accepting stationary phase, tributyl phosphate (TBP), which retains carboxylic acid selectivity, was more selective than more common reversed-phase systems with alkyl-bonded stationary phases. The mobile phases were buffers, sometimes buffers containing methanol or acetonitrile. A simple method of removing late peaks in the chromatogram, in order to reduce analysis time, is also presented.