Novel LC-MS/MS Method for Simultaneous Determination of Monoamine Neurotransmitters and Metabolites in Human Samples

For the simultaneous determination of monoamine neurotransmitters (NTs) like dopamine, serotonin, noradrenaline, and epinephrine, and their metabolites (metanephrine, normetanephrine, 3-methoxytyramine, vanillylmandelic acid, 3,4-dihydroxyphenylacetic acid, homovanillic acid, and 5-hydroxyindoleacetic acid), a robust liquid chromatography method coupled with tandem mass spectrometry (LC-MS/MS) was introduced as the analytical method. This analytical method proved to be accurate for the simultaneous measurement of the amounts of 11 NTs and their metabolites in biological samples. The method proved to be more efficient and better than the previously reported method in terms of precision, recovery, sample requirement, and extraction procedure. The reported method requires only 100 μL of blood and 200 μL of urine, and the extraction procedure requires acetonitrile precipitation, filtration, drying, and reconstitution in water. The separation of all analytes was performed on an C18 column (4.6 mm × 150 mm and 1.8 μm). A 10 min gradient elution program with a mobile phase consisting of phase A (0.2% formic acid in water) and phase B (methanol) was used. The positive ionization mode was used for the detection of all analytes in multiple reaction monitoring (MRM). The proposed method was validated with an internal standard and yielded lower limits of detection and quantification ranges of 0.0182-0.0797 ng/mL and 0.0553-0.2415 ng/mL, respectively, with a good linearity (R2) between 0.9959 and 0.9994. The recoveries ranged from 73.37% to 116.63% in blood and from 80.9% to 115.33% in urine. For the NTs and metabolites, the intra- and interday % CV were 0.24-9.36 and 0.85-9.67, respectively. The developed LC-MS/MS method was successfully used for the determination of trace amounts of endogenous compounds in human blood and urine samples.

Analytical method for urinary homovanillic acid and 5-hydroxyindoleacetic acid levels using HPLC with electrochemical detection applied to evaluate children environmentally exposed to manganese

Homovanillic acid (HVA) and 5-hydroxyindoleacetic acid (5-HIAA) are the urinary metabolites of dopamine (DA) and serotonin (5-HA), respectively. We aimed to develop an extraction method for the determination of HVA and 5-HIAA, using strong anionic exchange cartridges combined with HPLC with electrochemical detection, and apply it to measure the levels of HVA and 5-HIAA in children living near a ferro-manganese alloy plant in Simões Filho, Brazil. The validated method showed good selectivity, sensitivity, precision, and accuracy. The limits of detection (LOD) were 4 and 8 μmol/L for 5-HIAA and HVA, respectively, in urine. Recoveries ranged from 85.8 to 94%. The coefficients of determination (R2 ) of the calibration curves were greater than 0.99. Spot urine samples of 30 exposed children and 20 nonexposed ones were processed accordingly. The metabolite levels in exposed and reference children were within the physiological ranges. The medians (range) for 5-HIAA and HVA of the exposed ones were 36.4 μmol/L (18.4-58.0) and 32.9 μmol/L ( Collapse

Key Words

• 5-HIAA
• HPLC-ECD
• HVA
• dopamine
• manganese exposure
• serotonin

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MESH Headings

• Humans
• Child
• Homovanillic Acid/urine
• Hydroxyindoleacetic Acid
• Chromatography, High Pressure Liquid/methods
• Manganese
• Dopamine/metabolism

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Grants

• JCB0029/2015 Fundação de Amparo à Pesquisa do Estado da Bahia

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Affiliation(s)

Mariana Silva Cardoso Graduate Program in Pharmacy, College of Pharmacy, Federal University of Bahia, Salvador, Brazil
Andrea Rebouças Rocha Graduate Program in Food Science, College of Pharmacy, Federal University of Bahia, Salvador, Brazil
José Antônio Souza-Júnior Laboratory of Toxicology, College of Pharmacy, Federal University of Bahia, Salvador, Brazil
José Antonio Menezes-Filho Graduate Program in Pharmacy, College of Pharmacy, Federal University of Bahia, Salvador, Brazil Graduate Program in Food Science, College of Pharmacy, Federal University of Bahia, Salvador, Brazil Laboratory of Toxicology, College of Pharmacy, Federal University of Bahia, Salvador, Brazil

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UiO-66-based metal-organic framework for dispersive solid-phase extraction of vanillylmandelic acid from urine before analysis by capillary electrophoresis

Dispersive solid-phase extraction (DSPE) was developed for the extraction of vanillylmandelic acid (VMA) in urine samples prior to capillary electrophoresis with diode array detection (CE-DAD). Extraction of VMA by DSPE was carried out by direct addition of 7.5 mg of synthesized amino-functionalized UiO-66 (Zr) metal-organic framework adsorbent into the 5 mL sample solution (pH 4.0), followed by sonication and centrifugation. The supernatant layer was discarded, then the sedimented adsorbent was eluted using borate buffer (75 mM, pH 10). Effective extraction parameters including the amount of adsorbent, sample pH, adsorption and desorption time, type, volume and pH of eluent, and type of adsorbent dispersion method were systematically investigated. Under the optimized conditions, linearity of the method was from 40 to 2000 μg L^-1 with a correlation coefficient over 0.9948. The method detection and quantification limits were 12 and 40 μg L^-1, respectively. The relative standard deviations for intra-and inter-day precision were 2.4 and 2.8% (n = 5), respectively. The extraction recovery and enrichment factor values were 90% and 9.0 respectively.

Experiences of Discrimination and Urinary Catecholamine Concentrations: Longitudinal Associations in a College Student Sample

BACKGROUND

Experiences of discrimination are a risk factor for subsequent cardiovascular disease. However, there is a lack of longitudinal research examining associations between discrimination and urinary catecholamines. This is surprising given the likely mediating role of sympathetic nervous system dysregulation in the association between psychosocial stress and cardiovascular morbidity.

PURPOSE

The current study examined the 3 year longitudinal association between experiences of discrimination and urinary catecholamines.

METHODS

The sample included 149 college students (mean age at baseline = 18.8, standard deviation = 0.96; 45% Black/African American; 55% White/European American). Concentrations of epinephrine and norepinephrine-urinary catecholamines with established links to psychosocial stress exposure and subsequent morbidity-were determined from 12 hr overnight samples.

RESULTS

Results indicated that experiences of discrimination were associated with increases in both epinephrine (β = .284, standard error [SE] = .117, p = .015) and norepinephrine (β = .306, SE = .114, p = .001). These longitudinal associations persisted after adjusting for negative affect, depression, and rejection sensitivity and did not vary as a function of race/ethnicity.

CONCLUSIONS

Results suggest that examination of overnight urinary catecholamines as a biological mediator of associations between experiences of discrimination and cardiovascular morbidity is warranted.

A new approach for urinary vanillylmandelic acid determination using eVol microextraction by packed sorbent coupled to liquid chromatography-tandem mass spectrometry

Vanillylmandelic acid (VMA) is one of the most important catecholamine metabolites, and it is usually used to aid in diagnosis of pheochromocytoma and paraganglioma. A new digital control microextraction by packed sorbent (MEPS) procedure coupled to liquid chromatography-mass spectrometry (LC-MS/MS) method has been developed to determine VMA in human urine. We evaluated important parameters influencing MEPS efficiency, including stationary phase, extracting cycles, and sample dilution. In optimized MEPS conditions, Only 10 μL of sample volume and 3 min preparation time for one sample were needed. Chromatographic separation was achieved with a hydrophilic interaction liquid chromatography (HILIC) column using gradient elution. VMA was detected using multiple reaction monitoring (MRM) with an electrospray source operating in negative ion mode. The method was validated for linearity, limit of quantification, accuracy, imprecision, matrix effect, and interference. Linearity was 0.5–100 μg/mL for VMA. Intra-assay, inter-assay, and total imprecision were less than 9.6%. Interferences precluding quantitation of VMA in dilute-and-shoot approach were reduced significantly using a MEPS approach. Method comparison of LC-MS/MS and homogeneous enzyme immunoassay was performed, and the reference interval was established. The developed MEPS-LC-MS/MS method certainly contributes to method robustness and makes it suitable for measurement of urinary VMA in routine clinical biochemistry laboratories.

Recent Trends in the Quantification of Biogenic Amines in Biofluids as Biomarkers of Various Disorders: A Review

Biogenic amines (BAs) are bioactive endogenous compounds which play a significant physiological role in many cell processes like cell proliferation and differentiation, signal transduction and membrane stability. Likewise, they are important in the regulation of body temperature, the increase/decrease of blood pressure or intake of nutrition, as well as in the synthesis of nucleic acids and proteins, hormones and alkaloids. Additionally, it was confirmed that these compounds can be considered as useful biomarkers for the diagnosis, therapy and prognosis of several neuroendocrine and cardiovascular disorders, including neuroendocrine tumours (NET), schizophrenia and Parkinson's Disease. Due to the fact that BAs are chemically unstable, light-sensitive and possess a high tendency for spontaneous oxidation and decomposition at high pH values, their determination is a real challenge. Moreover, their concentrations in biological matrices are extremely low. These issues make the measurement of BA levels in biological matrices problematic and the application of reliable bioanalytical methods for the extraction and determination of these molecules is needed. This article presents an overview of the most recent trends in the quantification of BAs in human samples with a special focus on liquid chromatography (LC), gas chromatography (GC) and capillary electrophoresis (CE) techniques. Thus, new approaches and technical possibilities applied in these methodologies for the assessment of BA profiles in human samples and the priorities for future research are reported and critically discussed. Moreover, the most important applications of LC, GC and CE in pharmacology, psychology, oncology and clinical endocrinology in the area of the analysis of BAs for the diagnosis, follow-up and monitoring of the therapy of various health disorders are presented and critically evaluated.

Analytical validation and clinical application of urinary vanillylmandelic acid and homovanillic acid by LC-MS/MS for diagnosis of neuroblastoma

Vanillylmandelic acid (VMA) and homovanillic acid (HVA) are clinical biomarkers for diagnosis of neuroblastoma (NB), which commonly occurs in the childhood. Development and application of a robust LC-MS/MS method for fast determination of these biomarkers for optimal laboratory testing of NB is essential in clinical laboratories. In present study, we developed and validated a simple liquid chromatography tandem mass spectrometry (LC-MS/MS) method for quick clinical testing of VMA and HVA for diagnosis of NB. The method was validated according to the current CLSI C62-A and FDA guidelines. The age-adjusted pediatric reference intervals and diagnostic performance were evaluated in both 24 h urine and random urine. Injection-to-injection time was 3.5 min. Inter- and intra-assay coefficients of variation (CVs) were ≤3.88%. The lower limit of quantification and the limit of detection were 0.50 and 0.25 μmol/L for both VMA and HVA. Recoveries of VMA and HVA were in the ranges of 85-109% and 86-100% with CVs ≤5.76%. This method was free from significant matrix effect, carryover and interference. The establishment of age-adjusted pediatric reference intervals by this LC-MS/MS method was favorable for the improvement in diagnostic performance, which was crucial for correct interpretation of test results from children in both 24 h and random urine.

Comprehensive, robust, and sensitive UPLC-MS/MS analysis of free biogenic monoamines and their metabolites in urine

Biogenic monoamines, including catecholamines and serotonin are important hormones and neurotransmitters. Abnormal urinary levels of biogenic monoamines and their metabolites are associated with smoking, neuroendocrine tumors, as well as neurological and cardiovascular diseases. Measurements of free biogenic monoamines and their metabolites have been challenging because of low concentrations in complex biological matrices. Current methods require extensive enrichment and removal of interfering substances and can analyze only basic or acidic compounds in a single run. We developed a simple and robust dilute-and-shoot method capable of measuring 10 analytes, including free biogenic monoamines and their metabolites in human urine. The assay enables sensitive measurements of analytes within expected sample concentration ranges. To assess the assay's efficacy, we measured urinary levels of free biogenic monoamines and their metabolites in 255 non-smokers and 191 smokers. Our data show that while smokers had significantly higher urinary levels of free catecholamines and metanephrines, there was a decrease in levels of biogenic amine metabolites synthesized through the monoamine oxidase pathway - homovanillic acid and vanillylmandelic acid. The method could be used for high throughput measurement of the range of free biogenic amines and their metabolites in urine under a variety of different conditions.

Physiological linkage of gender, bioavailable hydroxytyrosol derivatives, and their metabolites with systemic catecholamine metabolism

Despite extensive characterization of hydroxytyrosol (HT), there is a gap in the knowledge about its capacity to modulate catecholamine pathways. This study deals with the evaluation of the effects of HT, hydroxytyrosol acetate (HTA), and 3,4-dihydroxyphenylacetic acid (DOPAC), as well as their microbial metabolites (homovanillyl alcohol and tyrosol), on the excretion of catecholamines by UHPLC-ESI-QqQ-MS/MS upon administration at 1 and 5 mg kg^-1 to male and female rats. The evaluation of urinary dopamine, norepinephrine, normetanephrine, and 3-methoxytyramine demonstrated 12.0- and 1.5-fold augmented excretions in males and females, respectively, due to the intake of HT derivatives. In addition, specific interconnections were identified between HT, HTA, DOPAC, and tyrosol and 3-methoxytyramine; between HTA and dopamine, norepinephrine, and normetanephrine; between HT, HTA, HVA, and tyrosol and dopamine, norepinephrine, and normetanephrine; and between HT, DOPAC, and HVA and dopamine and 3-methoxytyramine. Hence, a lack of linear relationships was observed between the oral administration of HT, HTA, and DOPAC and their plasma concentrations or urinary excretion levels after they were absorbed and distributed systemically. HT derivatives increase the synthesis of catecholamines in a derivative-, dosage-, and gender-dependent way.

Simple dilute-and-shoot method for urinary vanillylmandelic acid and homovanillic acid by liquid chromatography tandem mass spectrometry

BACKGROUND

Neuroblastomas are pediatric tumors characterized by overproduction of catecholamines. The catecholamine metabolites, vanillylmandelic acid (VMA) and homovanillic acid (HVA), are used in clinical evaluation of neuroblastoma. Tandem mass spectrometry (LC-MS/MS) is an effective analytical method for measurement of VMA and HVA in urine.

METHODS

Dilute-and-shoot sample preparation was performed in a 96-well format using a liquid handler. Chromatographic separation was achieved using a reverse phase column; detection was accomplished by triple quadrupole mass spectrometry with electrospray ionization in positive mode. Data were acquired by multiple reaction monitoring. Two transitions, quantifier and qualifier, were monitored for each analyte and its stable isotope-labeled internal standard. Analytical specificity studies were performed.

RESULTS

Injection-to-injection time was 4min. The method was validated for linearity, limit of quantification, imprecision, accuracy, and interference. Linearity was 0.5-100mg/l for both analytes. Within-run, between-day, and total imprecision were 1.0-4.1% for VMA and 0.8-3.8% for HVA. The method correlated well with our established HPLC method. Interferences precluding quantitation of VMA in 3% of specimens were reduced significantly (to 0.1% of specimens) using a modified LC gradient to reanalyze affected samples.

CONCLUSIONS

A simple, robust, economical, fast LC-MS/MS method was developed and validated for measurement of urinary VMA and HVA.

Ibuprofen transport in renal cell cultures: characterization of an ibuprofen transporter upregulated by hyperosmolarity

An ibuprofen transporter localizes to the apical and basolateral membrane of MDCK I cells is upregulated by hyperosmotic exposure. Ibuprofen uptake is inhibited by other NSAIDs and ibuprofen metabolites.

Preanalytical validation and reference values for a mass spectrometric assay of serum vanillylmandelic acid for screening of catecholamine secreting neuroendocrine tumors

BACKGROUND

Urinary vanillylmandelic acid (VMA) is used to diagnose and monitor catecholamine secreting neuroendocrine tumors (NETs). We developed and validated a new liquid chromatography tandem mass spectrometry (LC-MS/MS) assay for determination of serum VMA.

METHODS

We used serum samples from healthy volunteers (n=314) and patients suspected for NET (n=36). Deuterated VMA as an internal standard was added to samples before solid phase extraction (SPE) and LC-MS/MS analysis. We studied the effects of sample storage, sampling device and a meal on serum VMA and metanephrine concentrations. Diurnal variation and age-dependent reference intervals were established. The diagnostic performance was compared with a urinary HPLC assay for VMA and metanephrines and a serum metanephrine LC-MS/MS assay.

RESULTS

Serum VMA is stable at least for one day at +4°C, seven days at room temperature and 98 days at -20°C. Type of sampling device was not critical, but elevated serum VMA occurs after a meal (p = 0.031). Serum VMA increased with age. Therefore, we suggest clinical cut-off values of 62 nmol/L, 80 nmol/L and 108 nmol/L for age groups 18-50 yrs, 51-70 yrs and > 70 yrs, respectively. Comparison between a urinary VMA HPLC assay and serum VMA LC-MS/MS assay showed good correlation.

CONCLUSIONS

Our LC-MS/MS assay is fast and sensitive and suits well for use in a clinical laboratory. Compared to 24-h urine collection our serum assay enables well controlled sampling and convenient preanalytical steps.

LC–MS/MS in endocrinology: what is the profit of the last 5 years?

Currently, chromatography (GC but more commonly HPLC) is the analytical method of choice for several hormones, either because the immunoassays suffer from extensive crossreactivity or because chromatography permits simultaneous measurements of hormones. However, sometimes the conventional detection systems with HPLC methods do not meet desired specificity. With the increase of robust and affordable LC–MS/MS systems, the next step forward in specificity was taken. LC–MS/MS is rapidly being incorporated in the endocrine laboratories. To be useful in the clinical diagnostic practice, it is of utmost importance that methods are both analytically and clinically vaidated, as until now, the majority of applications of LC–MS/MS in the clinical laboratories are ‘home-made’ methods, therefore special case must be taken. This review aims to focus on Clinical and Laboratory Standards Institute or comparable validated LC–MS/MS methods for targeted hormone analysis used for diagnostic purposes in human samples, published in the last 5 years.