Simultaneous determination of three estrogens in human saliva without derivatization or liquid-liquid extraction for routine testing via miniaturized solid phase extraction with LC-MS/MS detection.

Accurate quantitation of estrogens (i.e, estrone (E1), estradiol (E2) and estriol (E3)) is valuable for clinical assessment of human health and disease. Alterations in estrogen levels have been implicated in numerous pathological conditions.

A simple dilute and shoot approach incorporated with pentafluorophenyl (PFP) column based LC-MS/MS assay for the simultaneous determination of trimethylamine N-oxide and trimethylamine in spot urine samples with high throughput.

Determination of trimethylamine N-oxide (TMAO) and trimethylamine (TMA) in biological and environmental samples has drawn great attention recently due to their increasing association with human health and disease. It remains a challenge to simultaneously quantify TMAO and TMA in a simple, fast and cost-effective manner due to pre-analytical and analytical constraints. For the first time, we describe a dilute and shoot approach combined with LC-MS/MS detection for the simultaneous measurement of the analytes in spot urine samples with high throughput.

Integration of Miniaturized Solid Phase Extraction and LC-MS/MS Detection of 3-Nitrotyrosine in Human Urine for Clinical Applications.

Free 3-nitrotyrosine (3-NT) has been extensively used as a possible biomarker for oxidative stress. Increased levels of 3-NT have been reported in a wide variety of pathological conditions. However, existing methods lack the sufficient sensitivity and/or specificity necessary to measure the low endogenous level of 3-NT reliably and are too cumbersome for clinical applications.

Simultaneous extraction and determination of monoamine neurotransmitters in human urine for clinical routine testing based on a dual functional solid phase extraction assisted by phenylboronic acid coupled with liquid chromatography-tandem mass spectrometry.

The major monoamine neurotransmitters, serotonin (5-HT) and catecholamines (i.e., norepinephrine (NE), epinephrine (E), and dopamine (DA)), are critical to the nervous system function, and imbalances of the neurotransmitters have been connected to a variety of diseases, making their measurement useful in a clinical setting.

Pre-analytical and analytical validations and clinical applications of a miniaturized, simple and cost-effective solid phase extraction combined with LC-MS/MS for the simultaneous determination of catecholamines and metanephrines in spot urine samples.

It remains a challenge to simultaneously quantify catecholamines and metanephrines in a simple, sensitive and cost-effective manner due to pre-analytical and analytical constraints. Herein, we describe such a method consisting of a miniaturized sample preparation and selective LC-MS/MS detection by the use of second morning spot urine samples. Ten microliters of second morning urine sample were subjected to solid phase extraction on an Oasis HLB microplate upon complexation with phenylboronic acid.

An integrated liquid chromatography-tandem mass spectrometry approach for the ultra-sensitive determination of catecholamines in human peripheral blood mononuclear cells to assess neural-immune communication.

Catecholamines play a vital role in the interactions between the nervous and immune systems and their dysfunctions are implicated in various autoimmune and neurological diseases. However, accurate quantitation of catecholamines in the immune system presents a special analytical challenge. We proposed the first LC-MS/MS method for the determination of catecholamines in human peripheral blood mononuclear cells (PBMC) with significantly improved sensitivity, selectivity and throughput without requiring derivatization, evaporation and ion-pairing reagent.

Tailored 96-well μElution solid-phase extraction combined with UFLC-MS/MS: a significantly improved approach for determination of free 3-nitrotyrosine in human urine.

We developed and validated a simple and fast UFLC-MS/MS method for the accurate determination of 3-nitrotyrosine (3-NT) in human urine as a noninvasive biomarker for oxidative stress. The method, involving tailored 96-well μElution solid-phase extraction (SPE) combined with UFLC-MS/MS, allows 3-NT to be determined in biological samples without the need for hydrolysis, derivatization, evaporation, and two-dimensional LC for the first time. Using ammonium acetate (pH 9, 25 mM) as an elution buffer was found to improve SPE selectivity.

A novel mixed-mode solid phase extraction coupled with LC-MS/MS for the re-evaluation of free 3-nitrotyrosine in human plasma as an oxidative stress biomarker.

3-Nitrotyrosine (3-NT) has been widely adopted as a biomarker of oxidative stress. However, an enormous range of reported concentrations of 3-NT in biological matrices indicated an underlying methodological problem. Consequently, our understanding of tyrosine nitration in vivo and its significance as a biomarker may have been confounded.

Development and validation of a specific and sensitive LC-MS/MS method for quantification of urinary catecholamines and application in biological variation studies.

Catecholamines are a class of biogenic amines that play an important role as neurotransmitters and hormones. We developed and validated a rapid, specific and sensitive LC-MS/MS method for quantitative determination of catecholamines in human urine. Linearity, specificity, sensitivity, precision, accuracy, matrix effect, carryover, analyte stability, method comparison and reference range were evaluated.