Simultaneous analysis of human plasma catecholamines by high-performance liquid chromatography with a reversed-phase triacontylsilyl silica column

Serially coupled columns enhance rapid separation and predictive interaction understanding of 93 fentanyl analogs

BACKGROUND

The simplicity of synthesis methods has facilitated the illegal manufacture of various fentanyl analogs, leading to numerous fatal overdoses worldwide, particularly in North America. Fentanyl analogs with similar structures are difficult to distinguish due to their fragmentation patterns, making separation using chromatography essential. Additionally, because fentanyl analogs are lethal even in trace amounts, they are easily smuggled, and commonly used fentanyl test strips often fail to detect them due to their low sensitivity. Therefore, the urgent need for analytical methods that can simultaneously identify multiple analogs and swiftly detect them at low concentrations.

RESULTS

In this study, liquid chromatography-tandem mass spectrometry was conducted to screen 93 types of fentanyl analogs among the illegal fentanyl substances. The phenyl-hexyl columns enhance fentanyl analog separation through strong π-π interactions. The serially coupled column system increased the separation efficiency and mitigated peak distortion, particularly those of polar fentanyl analogs. The selectivity varied significantly, depending on the interactions with the combined columns. The phenyl-hexyl column's superior ability to predict fentanyl analog interactions based on molecular structure was confirmed by retention factor analysis. The resolution of fentanyl isomers increased significantly when methanol was used instead of acetonitrile as an organic modifier in the mobile phase. The approach was validated by determining the limits of detection and quantification, specificity, detection capability, recovery, and relative ion intensity.

SIGNIFICANCE

The fentanyl analogs, including 23 sets of isomeric and isobaric compounds, were analyzed via separation using a phenyl-hexyl column serially coupled with a cyano column. The serially coupled column system increased the separation efficiency and mitigated peak distortion, particularly those of polar fentanyl analogs. The proposed strategy can be adopted in exploring methods of effectively separating mixtures with diverse properties, aiding the prevention of drug abuse and bolstering public health and safety efforts.

Efficient Sub-1 Minute Analysis of Selected Biomarker Catecholamines by Core-Shell Hydrophilic Interaction Liquid Chromatography (HILIC) with Nanomolar Detection at a Boron-Doped Diamond (BDD) Electrode

A rapid, sensitive method for the separation of catecholamine biomarkers (CAs), of importance in traumatic brain injury (TBI) and in Parkinson’s disease (PD), has been successfully developed using hydrophilic interaction liquid chromatography (HILIC). Dopamine (DA), epinephrine (EPI), and norepinephrine (NE) are known to be three to fivefold elevated above normal in traumatic brain injury (TBI) patients. HILIC facilitates the rapid and efficient separation of these polar biomarkers, which can be poorly retained by reversed-phase liquid chromatography (RPLC), while electrochemical detection (ECD) at the boron-doped diamond (BDD) electrode provides enhanced nanomolar detection. Three HILIC columns were compared, namely the superficially porous (core-shell) Z-HILIC column and the Z-cHILIC and Z-HILIC fully porous columns. The core-shell Z-HILIC showed the highest efficiency with a rapid separation within 60 s. The HILIC method utilizing the core-shell Z-HILIC column was initially optimized for the simultaneous analysis of DA, EPI, and NE using UV detection. The advantages of using the BDD electrode over UV detection were explored, and the improved limits of detection (LODs, S/N = 3) measured were 40, 50, and 50 nM for DA, EPI, and NE, respectively. Method validation is reported in terms of the linearity, repeatability, reproducibility, and LODs. Furthermore, the proposed method was successfully applied to the real sample analysis of urinary CAs following phenylboronic acid (PBA) solid phase extraction (SPE) pretreatment.

Analysis of Catecholamines and Pterins in Inborn Errors of Monoamine Neurotransmitter Metabolism-From Past to Future

Inborn errors of monoamine neurotransmitter biosynthesis and degradation belong to the rare inborn errors of metabolism. They are caused by monogenic variants in the genes encoding the proteins involved in (1) neurotransmitter biosynthesis (like tyrosine hydroxylase (TH) and aromatic amino acid decarboxylase (AADC)), (2) in tetrahydrobiopterin (BH₄) cofactor biosynthesis (GTP cyclohydrolase 1 (GTPCH), 6-pyruvoyl-tetrahydropterin synthase (PTPS), sepiapterin reductase (SPR)) and recycling (pterin-4a-carbinolamine dehydratase (PCD), dihydropteridine reductase (DHPR)), or (3) in co-chaperones (DNAJC12). Clinically, they present early during childhood with a lack of monoamine neurotransmitters, especially dopamine and its products norepinephrine and epinephrine. Classical symptoms include autonomous dysregulations, hypotonia, movement disorders, and developmental delay. Therapy is predominantly based on supplementation of missing cofactors or neurotransmitter precursors. However, diagnosis is difficult and is predominantly based on quantitative detection of neurotransmitters, cofactors, and precursors in cerebrospinal fluid (CSF), urine, and blood. This review aims at summarizing the diverse analytical tools routinely used for diagnosis to determine quantitatively the amounts of neurotransmitters and cofactors in the different types of samples used to identify patients suffering from these rare diseases.

LC–MS/MS method for quantification of 3,4-dihydroxyphenylglycol, a norepinephrine metabolite in plasma and brain regions

Aim: To evaluate suitability of the LC–MS/MS method to quantify 3,4-dihydroxyphenylglycol (DHPG) that is used as a biomarker for monoamine oxidase (MAO) inhibition. Methods: DHPG was extracted using alumina basic cartridges and quantified on a triple quadrupole mass spectrometer using negative electrospray ionization, without the use of derivatization reagents. Results: Modulation of DHPG levels was observed following administration of selective and nonselective MAO inhibitors and results were in correlation with historical MAO inhibition potential of compounds. Conclusion: The proposed method is sensitive enough to measure plasma DHPG levels and DHPG can be used as a biomarker to assess MAO inhibition potential of new therapeutic agents.

Facile synthesis of boronic acid-functionalized magnetic metal-organic frameworks for selective extraction and quantification of catecholamines in rat plasma

Precise determination of the endogenous catecholamines, dopamine (DA), epinephrine (E) and norepinephrine (NE) faces substantial challenges due to their low physiological concentrations in plasma. We synthesized, for the first time, a magnetic metal-organic framework (MIL-100) composite with boronic acid-functionalized pore-walls (denoted as MG@MIL-100-B composite) using a metal-ligand-fragment coassembly (MLFC) strategy. The composites were then applied as an effective magnetic solid-phase extraction (SPE) sorbent for determination of trace catecholamine concentrations in rat plasma through coupling with HPLC-MS/MS. The obtained nano-composites exhibited high magnetic responsivity, uniform mesopores, large specific surface area, and boronic acid-functionalized inner pore-walls. Catecholamines in rat plasma were extracted through interaction between the cis-diol structures and the boronic acid groups in the MG@MIL-100-B composites. Extraction conditions were optimized by studying SPE parameters including adsorption and desorption time, elution solvent type, pH conditions and adsorbent amount. With our approach, the detection limits (S/N = 3) were as low as 0.005 ng mL-1 for DA and E, and 0.02 ng mL-1 for NE. Intra- and inter-day precision ranged from 2.84-6.63% (n = 6) and 5.70-11.44% (n = 6), respectively. Recoveries from spiking experiments also showed satisfactory results of 94.40-109.51%. Finally, the MG@MIL-100-B composites were applied successfully to determine catecholamine concentrations in rat plasma.

Development of a simple and rapid solid phase microextraction-gas chromatography-triple quadrupole mass spectrometry method for the analysis of dopamine, serotonin and norepinephrine in human urine

The work aims at developing a simple and rapid method for the quantification of dopamine (DA), serotonin (5-HT) and norepinephrine (NE) in human urine. The urinary levels of these biogenic amines can be correlated with several pathological conditions concerning heart disease, stress, neurological disorders and cancerous tumors. The proposed analytical approach is based on the use of solid phase microextraction (SPME) combined with gas chromatography-triple quadrupole mass spectrometry (GC-QqQ-MS) after a fast derivatization of both aliphatic amino and phenolic moieties by propyl chloroformate. The variables influencing the derivatization reaction were reliably optimized by the multivariate approach of "Experimental design". The optimal conditions were obtained by performing derivatization with 100μL of propyl chloroformate and 100μL of pyridine. The extraction ability of five commercially available SPME fibers was evaluated in univariate mode and the best results were obtained using the polyacrylate fiber. The variables affecting the efficiency of SPME analysis were again optimized by the multivariate approach of "Experimental design" and, in particular, a central composite design (CCD) was applied. The optimal values were extraction in 45min at room temperature, desorption temperature at 300°C, no addition of NaCl. Assay of derivatized analytes was performed by using a gas chromatography-triple quadrupole mass spectrometry (GC-QqQ-MS) system in selected reaction monitoring (SRM) acquisition. An evaluation of all analytical parameters demonstrates that the developed method provides satisfactory results. Indeed, very good linearities were achieved in the tested calibration range with correlation coefficient values of 0.9995, 0.9999 and 0.9997 for DA, 5-HT and NE, respectively. Accuracies and RSDs calculated for between-run and tested at concentrations of 30, 200, and 800μg L(-1) were in the range from 92.8% to 103.0%, and from 0.67 to 4.5%, respectively. Finally, the LOD values obtained can be considered very good (0.587, 0.381 and 1.23μg L(-1) for DA, 5-HT and NE, respectively).

The transcriptional profile of Paracoccidioides brasiliensis yeast cells is influenced by human plasma

Paracoccidioides brasiliensis causes infection through host inhalation of airborne propagules of the mycelial phase of the fungus, which reach the lungs, and then disseminate to virtually all parts of the human body. Here we describe the identification of differentially expressed genes in P. brasiliensis yeast cells, by analyzing cDNA populations from the fungus treated with human plasma, mimicking superficial infection sites with inflammation. Our analysis identified transcripts that are differentially represented. The transcripts upregulated in yeast cells during incubation in human plasma were predominantly related to fatty acid degradation, protein synthesis, sensing of osmolarity changes, cell wall remodeling and cell defense. The expression pattern of genes was independently confirmed.

Determination of endogenous norepinephrine levels in different chambers of the rat heart by capillary electrophoresis coupled with amperometric detection

Capillary electrophoresis with end-column amperometric detection (CE-EC) was used to determine the regional distribution of norepinephrine (NE) in the hearts of sympathetically innervated (control) and chemically sympathectomized rats. Key features of the method are (i) the sample preparation and clean-up step that involved the application of off-line solid phase extraction (SPE) with a 95% NE recovery and (ii) the use of a diamond microelectrode for detection. NE was quantified in the left and right ventricle, the ventricular septum, and the left and right atrium. The NE concentration in the atria was three to five times higher than in the ventricles and ventricular septum of control rats. Basal NE levels in the left and right ventricle and the ventricular septum were reduced to below the detection limit (0.034 microg/g tissue) in tissues treated with the neurotoxin, 6-hydroxydopamine (6-OHDA), while only a moderate reduction was observed in the left and right atrium. Importantly, the diamond microelectrode provided low and stable background current and low peak-to-peak noise <or=0.65 pA at a detection potential of +0.86 V versus Ag/AgCl. A reproducible electrode response was observed for multiple injections of tissue homogenates with minimal response attenuation due to electrode fouling.

Determination of catecholamines and serotonin by micellar electrokinetic chromatography with laser-induced fluorescence detection

6-Oxy-(N-succinimidyl acetate)-9-(2'-methoxycarbonyl) fluorescein, a new synthesized fluorescent reagent, was established for the first time as a label for the sensitive analysis of catecholamines (CAs) and serotonin (5-HT) by micellar electrokinetic chromatography (MEKC) with laser-induced fluorescence detection. After careful study on the derivatization conditions such as pH value, reagent concentration, temperature and reaction time, the labeling reaction was accomplished as quickly as 7 min with stable yield. The separation parameters for the CAs and 5-HT were also optimized in detail. The derivatives were baseline separated in a running buffer containing 30 mM boric acid and 15 mM sodium dodeculsulfate at pH 9.0. The detection limits ranged from 5 x 10(-10) to 2 x 10(-9) M (signal-to-noise ratio = 3). The rapid and sensitive method was also applied to the determination of the CAs and 5-HT of urine samples.

A simple and rapid HPLC-MS method for the simultaneous determination of epinephrine, norepinephrine, dopamine and 5-hydroxytryptamine: application to the secretion of bovine chromaffin cell cultures

This method simultaneously determines epinephrine, norepinephrine, dopamine and 5-hydroxytryptamine by HPLC coupled to atmospheric pressure chemical ionization mass spectrometry, using bovine chromaffin cells to test xenobiotic neurotoxicity and the secretion alterations of these neurotransmitters as endpoint. Chromatographic separation was developed by injecting the sample without previous treatment into a reversed-phase column. The signal was recorded in selected ion mode. The lowest limit of detection was found for hydroxytryptamine, while the highest limit was for norepinephrine. The feasibility of the proposed method was checked by performing measurements of neurotransmitters during the assessment the effect of mipafox on the basal and potassium-induced secretions of chromaffin cell cultures.