Ionic liquid based ultrasound assisted dispersive liquid-liquid micro-extraction for simultaneous determination of 15 neurotransmitters in rat brain, plasma and cell samples

Pharmacokinetic and pharmacodynamic studies of nicotine in rat brain: a simultaneous investigation of nicotine metabolites and the release of neurotransmitters in vivo

Introduction: The body's ability to metabolize nicotine and the disposition of nicotine in the brain are important determinants of its exposure. Limited knowledge about the near real-time changes of neurochemicals during the brain nicotine metabolic process hinders the recognition of its multiple neuropharmacological effects. Methods: An online microdialysis coupled with UHPLC-HRMS/MS method for the in vivo multi-analysis of nicotine metabolites and several neurotransmitters in rat brain was developed. Whether the systemic modulation of metabolic enzyme CYP2B would modulate nicotine pharmacokinetics and local neurochemical effects was further investigated. Results: The dynamic profiles of over 10 nicotine metabolites and neurotransmitters were simultaneously obtained after a single injection of nicotine (2 mg·kg-1, i.p.) using the new method. Proadifen pretreatment (50 mg·kg-1·d-1, i.p., 4 days) caused significant inhibition of brain CYP2B1 activity. When exposed to nicotine, the brain C max of nicotine was 1.26 times higher and the levels of nicotine metabolites, nornicotine, and nicotine-N-oxide, were decreased by 85.3% and 34.4% in proadifen-pretreated rats. The higher level of brain nicotine induced a greater release of dopamine, serotonin, glutamate, and γ-amino-butyric acid in the nucleus accumbens. The concentrations of nicotine and dopamine were positively correlated, and the average levels of γ-amino-butyric acid and serotonin were 2.7 and 1.2 times higher, respectively, under the inhibition of nicotine metabolism. Discussion: These results demonstrated that inhibiting nicotine metabolism in rats can enhance the residence of brain nicotine and its local neurotransmitter effects. The metabolic activity of nicotine under different physiological conditions could regulate nicotine's bioavailability and its resulting pharmacology.

Magnetic ionic liquid-based liquid-liquid microextraction followed by ultra-performance liquid chromatography coupled with triple-quadrupole tandem mass spectrometry for simultaneous determination of neurotransmitters in human cerebrospinal fluid and plasma

A green, efficient and easy sample pretreatment method of magnetic ionic liquid-based liquid-liquid microextraction (MIL-based LLME) combined with a sensitive, rapid and precise analytical method of ultra-performance liquid chromatography coupled with triple-quadrupole tandem mass spectrometry (UPLC-QqQ/MS²) was developed to simultaneously - determining of neurotransmitters (NTs) in biosamples. Two magnetic ionic liquids (MILs), [P_6,6,6,14]₃[GdCl₆] and [P_6,6,6,14]₂[CoCl₄] tested, and the latter was selected as the extraction solvent due to its advantages of visual recognition, paramagnetic behavior and higher extraction efficiency. Facile magnetic separation of MIL containing analytes from matrix was realized by applying external magnetic field without rather than centrifugation. Experimental parameters that would influence the extraction efficiency, including type and amount of MIL, extraction time, speed of the vortex process, salt concentration, and environmental pH, were optimized obtained. The proposed method was successfully applied to the simultaneous extraction and determination of 20 NTs in human cerebrospinal fluid and plasma samples. Excellent analytical performance indicates the broad potential of this method for clinical diagnosis and therapy of neurological diseases.

Detection, quantification and degradation kinetic for five benzodiazepines using VAUS-ME-SFO/LC-MS/MS method for water, alcoholic and non-alcoholic beverages

Benzodiazepines can make victims more docile, they are frequently used in drug-facilitated crimes, such as robberies and sexual assaults. Therefore, it is essential to develop techniques for determining whether these chemicals are present in relation with illegal activity is crucial. Therefore, to determine the presence of five benzodiazepines (alprazolam, clonazepam, diazepam, lorazepam, and oxazepam) in water, alcoholic beverages, and non-alcoholic beverages, a simple and direct, miniaturized, and effective vortex assisted ultrasound based microextraction using solidification of floating organic droplets (VAUS-ME-SFO) in combination with LC-MS/MS was developed. 1-Undecanol and acetonitrile, respectively, served as the extractant and disperser solvents. Many other parameters affect the efficiency of the developed analytical procedure VAUS-ME-SFO/LC-MS/MS. These parameters were optimized using Plackett Burman Design and Central Composite Design to obtain reliable results. The optimum conditions for the extraction were: 10.0 mL of sample; 180 μL acetonitrile, as a dispersive solvent; 200 μL of 1-undecanol, as an extraction solvent; pH 7; 105 s of vortex agitation; 120 s of ultrasonication application and 3 min of centrifugation at 7000 rpm. The benzodiazepines were separated by a chromatographic separation technique carried out by a UPLC system consisting of a binary mobile phase. The solvent system comprises of 0.1% Formic acid in Milli-Q (Solvent A) and 0.1% Formic acid in ACN (Solvent B) with a gradient flow of 3.5 min total analysis time. Under the optimized conditions, the calibration curve was studied in the range of 0.124-7.810 ng mL^-1. The regression correlation coefficient (R²) value of all targeted analytes ranges from 0.993 to 0.999. The LOD and LOQ of VAUS-ME-SFO methods using LC-MS/MS analysis range from 0.316 to 0.968 ng mL^-1 and 1.055-3.277 ng mL^-1 respectively. The repeatability within a day varied from 0.6 to 3.5%, and the reproducibility across days varied from 2.2 to 6.3%. The recoveries ranges for water, alcoholic and non-alcoholic beverages from 70.77 to 114.53%, 63.20-102.21% and 66.23-113.28% respectively. Further, the degradation kinetics was studied to establish the half-life of each targeted analyte in the matrix undertaken in the study. The water samples were classified based on their BDZs residues. This implies that the more health care and anthropogenic activity, the more the BDZs residue will be in water samples.

Investigation of Imidazolium-Based Ionic Liquids as Additives for the Separation of Urinary Biogenic Amines via Capillary Electrophoresis

Ionic liquids (ILs), such as imidazoles, can be used to prevent the sorption of analytes onto the walls of the capillary. Prior works have confirmed that coating the capillary wall with a cationic layer can increase its surface stability, thereby improving the repeatability of the separation process. In this study, micellar electrokinetic chromatography (MEKC) is employed to evaluate how two ILs with different anions—namely, 1-hexyl-3-methylimidazolium chloride [HMIM+Cl−] and 1-hexyl-3-methylimidazolium tetrafluoroborate [HMIM+BF4−]—affect the separation efficiency for biogenic amines (BAs) such as metanephrine (M), normetanephrine (NM), vanilmandelic acid (VMA), and homovanillic acid (HVA) in urine samples. To this end, solid-phase extraction (SPE) is employed using different sample pH values, with the results demonstrating that HVA and VMA is easily extracted at a sample pH of 5.5, while a sample pH of 9.0 facilitated the extraction of M and NM. In the applied SPE protocol, selected analytes were isolated from urine samples using hydrophilic–lipophilic-balanced (HLB) columns and eluted with methanol (MeOH). The validation data confirmed the method’s linearity (R2 > 0.996) for all analytes within the range of 0.25–10 µg/mL. The applicability of the optimized SPE-MEKC-UV method was confirmed by employing it to quantify clinically relevant BAs in real urine samples from pediatric neuroblastoma (NBL) patients.

Liquid chromatography-tandem mass spectrometry method for simultaneous quantification of neurotransmitters in rat brain tissue exposed to 4'-Fluoro-α-PHP

The combination of different advanced analytical techniques makes it possible to determine the concentrations of neurotransmitters in various biological matrices, providing a complex and comprehensive study of the effects of psychoactive substances. The present study aimed to develop and validate a fast and simple analytical method for the determination of acetylcholine, serotonin, γ-aminobutyric acid, glutamate, dopamine, and metabolites in rats brain tissue by liquid chromatography coupled to tandem mass spectrometry. The brain was homogenized and an aliquot of sample, dopamine-d₄ , and acetone were added in a tube and then vortexed and centrifuged. The supernatant was collected and dried. The residue was reconstituted and injected. LLOQ ranged from 0.001 to 1 μg/g; intra-run precision from 0.47 to 11.52%; inter-run precision from 0.68 to 17.54%; bias from 89.10 to 109.60%. As proof of concept, the method was applied to animals exposed to the synthetic cathinone 4'-fuoro-α-pyrrolidinohexanophenone (300 mg/kg). In addition, the workflow proved to be simple, rapid, and useful to estimate the concentration of neurotransmitters. This analytical tool can be used to support the investigation of the changes in the neurochemical profile for the characterization of the mechanism of action of psychoactive substances, as well as both neurologic and psychiatric diseases.

Determination of Six Tetracyclines in Eggs and Chicken by Dispersive Liquid-Liquid Microextraction Combined with High-Performance Liquid Chromatography

BACKGROUND

The wide livestock usage of tetracyclines may result in drug residues in foods. Therefore, it is necessary to develop reliable methods for the determination of tetracyclines in foods.

OBJECTIVE

A dispersive liquid-liquid microextraction (DLLME) combined with high-performance liquid chromatography (HPLC) method was developed for the analysis of six tetracyclines in eggs and chicken.

METHODS

After deproteinization, tetracyclines in acidic solutions were concentrated by vortex-assisted DLLME. Followed by the addition of NaCl (35% for eggs and 20% for chicken), a mixture of ionic liquid [Bmim]PF6 and ethyl acetate (300 μL-50 μL for eggs and 200 μL-60 μL for chicken) was used as the extractant. After centrifugation, the extract was collected for HPLC analysis.

RESULTS

The developed method showed good linear relationship (10.0-500 μg/kg), low method detection limits (0.219-1.42 μg/kg) and quantification limits (0.731-4.72 μg/kg), satisfactory relative recoveries (87.1-104%) with intra-day and inter-day RSDs in the ranges of 0.853-8.62% and 1.65-11.8%, respectively. The established method was successfully applied for the determination of six tetracyclines in eggs and chicken of different parts. The contents of tetracyclines in all samples were lower than their maximum residue limits.

CONCLUSIONS

A DLLME-HPLC method has been developed for the analysis of six tetracyclines in animal derived foods using ionic liquid and ethyl acetate as the extractant.

HIGHLIGHTS

The developed method is simple, sensitive, cost-effective and has strong anti-interference ability. This method has been successfully applied to the analysis of six tetracyclines in eggs and chicken.

Magnetic borate-modified Mxene: A highly affinity material for the extraction of catecholamines

A novel magnetic borate-modified MXene composite was prepared by in situ growth of Fe₃O₄ particles onto the surface of phenylboronic acid modified Ti₃C₂T_x nanosheets. The magnetic composite possesses highly selective recognition properties to catecholamines, and high adsorption capacity (up to 319.6 μmol g^-1) for dopamine. Besides, the adsorption of urinary catecholamines can be accomplished within 2.0 min. The excellent adsorption performance can be assigned to its unique 2D layered structures, which helps to shorten the diffusion path and facilitate molecular transport. In addition, the multilayer adsorption and the synergetic interactions of borate affinity, van der Waals forces, hydrogen bonding and π-π stacking also contribute to the adsorption. By coupling the magnetic boronate affinity composites with high-performance liquid chromatography-fluorescence detection, a sensitive method for the determination of catecholamines in urine samples was proposed. The validation results revealed it can offer good linearities (correlation coefficients higher than 99%). The method detection limits were 0.06, 0.16, 0.03 and 0.14 ng mL^-1 for norepinephrine, epinephrine, dopamine and isoprenaline, respectively, and relative recoveries for these catecholamines were in the range of 98.56-108.1%, 92.56-110.0%, 98.79-112.3% and 88.14-97.81%, respectively. The proposed method was successfully applied to analyze the catecholamines in the urine samples from 15 healthy volunteers and 16 patients with Alzheimer's disease. The results indicated that the magnetic borate-modified Mxene composite possesses superior extraction performance, and can be used as an outstanding candidate for the extraction of catecholamines in pre-clinical or clinical studies.

Research for improvement on the extract efficiency of lignans in traditional Chinese medicines by hybrid ionic liquids: As a case of Suhuang antitussive capsule

Recently, efficient extraction of natural products from traditional Chinese medicines (TCMs) by green solvents is deemed an essential area of green technology and attracts extensive attentions. In this work, a green protocol for simultaneous ultrasonic-extraction of the native compounds with different polarities of TCMs by using a hybrid ionic liquids (HILs)-water system was reported for the first time. As a case study, three superior ILs (1-ethyl-3-methylimidazolium tetrafluoroborate ([EMIM][BF4]), 1-ethyl-3-methylimidazolium acetate ([EMIM][OAc]), and 1-allyl-3-methylimidazolium chloride ([AMIM]Cl)) were chosen as the compositions of the HILs system, and the TCMs Suhuang antitussive capsule (SH) containing different-polarity lignans was selected. Primarily, an ultra-performance liquid chromatography coupled to triple quadrupole tandem mass spectrometry (UPLC-QqQ-MS/MS) method in the multiple reaction monitoring (MRM) mode was established for qualitative and quantitative analysis of 18 lignans. After majorization by uniform design experiment, the HILs prepared with [AMIM]Cl, [EMIM][BF4], and [EMIM][OAc] at a volume ratio of 1:5:5 could simultaneously extract multi-polarity lignans compared to single IL. Subsequently, the conditions of ultrasonic extraction employing with HILs and traditional organic solvent were optimized by the response surface methodology, respectively. The results indicated that the extract efficiency of the HILs system for target compounds was significantly improved compared with the traditional organic solvent-extraction, i.e. the content of total lignans in ethanol system was up to 47 mg/g, while that in the HILs system was up to 69 mg/g, with an increasing of 47%. Additionally, ¹H-NMR and ¹³C-NMR spectra were used to characterize the hydrogen-bond interactions in the HILs-lignan mixtures. Extraction with the HILs in TCMs is a new application schema of ILs, which not only avoids the use of volatile toxic organic solvents, but also shows the potential to be comprehensively applied for the extraction of bioactive compounds from TCMs.

Recent applications of microextraction sample preparation techniques in biological samples analysis

Analysis of biological samples is affected by interfering substances with chemical properties similar to those of the target analytes, such as drugs. Biological samples such as whole blood, plasma, serum, urine and saliva must be properly processed for separation, purification, enrichment and chemical modification to meet the requirements of the analytical instruments. This causes the sample preparation stage to be of undeniable importance in the analysis of such samples through methods such as microextraction techniques. The scope of this review will cover a comprehensive summary of available literature data on microextraction techniques playing a key role for analytical purposes, methods of their implementation in common biological samples, and finally, the most recent examples of application of microextraction techniques in preconcentration of analytes from urine, blood and saliva samples. The objectives and merits of each microextration technique are carefully described in detail with respect to the nature of the biological samples. This review presents the most recent and innovative work published on microextraction application in common biological samples, mostly focused on original studies reported from 2017 to date. The main sections of this review comprise an introduction to the microextraction techniques supported by recent application studies involving quantitative and qualitative results and summaries of the most significant, recently published applications of microextracion methods in biological samples. This article considers recent applications of several microextraction techniques in the field of sample preparation for biological samples including urine, blood and saliva, with consideration for extraction techniques, sample preparation and instrumental detection systems.

Is cerebral salt wasting related to sympathetic dysregulation in tuberculous meningitis?

BACKGROUND

Cerebral Salt wasting (CSW) is common in Tuberculous Meningitis (TBM) and is suggested to be due to sympathetic dysregulation of renal blood supply but has not been proven.

OBJECTIVE

To evaluate plasma Catecholamines in TBM patients with CSW and correlate with the markers of stress.

MATERIALS AND METHODS

The diagnosis of TBM was based on clinical, CSF and MRI criteria. Catecholamines level was measured by LC-MS on admission, at the time of hyponatremia and on correction of hyponatremia. Catecholamine levels were correlated with clinical and laboratory markers of stress, hyponatremia and severity of CSW using pre-defined criteria.

RESULTS

There were 24 patients with TBM (12 with CSW) and 12 controls. The median age of patients was 31 (18-75) years and 12 (50 %) were females. TBM patients with CSW had significantly higher levels of catecholamines compared to controls (p < 0.001). TBM patients with CSW had higher levels of norepinephrine than those without CSW (p = 0.034). Sequential studies revealed that dopamine and epinephrine increased at the time of hyponatremia and declined on its correction. Severity of TBM was related to dopamine (p = 0.04) and severity of CSW was related to epinephrine (p = 0.016).

CONCLUSION

CSW in TBM seems to be related to catecholamine dysregulation.

Review: Microextraction Technique Based New Trends in Food Analysis

Food chemistry is the study and classification of the quality and origin of foods. The identification of definite biomarkers and the determination of residue contaminants such as toxins, pesticides, metals, human and veterinary drugs, which are a very common source of food-borne diseases. The food analysis is continuously demanding the improvement of more robust, sensitive, highly efficient, and economically beneficial analytical approaches to promise the traceability, safety, and quality of foods in the acquiescence with the consumers and legislation demands. The traditional methods have been used at the starting of the 20th century based on wet chemical methods. Now it existing the powerful analytical techniques used in food analysis and safety. This development has led to substantial enhancements in the analytical accuracy, precision, sensitivity, selectivity, thereby mounting the applied range of food applications. In the present decade, microextraction (micro-scale extraction) pays more attention due to its futures such as low consumption of solvent and sample, throughput analysis easy to operate, greener, robotics, and miniaturization, different adsorbents have been used in the microextraction process with unique nature recognized with wide range applications.

Bioanalysis of pharmaceuticals using liquid-phase microextraction combined with liquid chromatography-mass spectrometry

In this paper, we review recent research articles on liquid-phase microextraction of drug substances from biological fluids, such as plasma, serum, urine, and saliva. We focus on papers where liquid-phase microextraction is combined with liquid chromatography coupled with mass spectrometry (LC-MS), published in the period 2019-2020. First, we discuss different configurations of liquid-phase microextraction, including dispersive liquid-liquid microextraction (DLLME), dispersive liquid-liquid microextraction based on solidified floating organic droplet (DLLME-SFO), single-drop microextraction (SDME), hollow-fibre liquid-phase microextraction (HF-LPME), solvent bar microextraction (SBME), and electromembrane extraction (EME). Second, we discuss new types of solvents used in liquid-phase microextraction, including ionic liquids, deep eutectic solvents, and nanostructured supramolecular solvents. Especially, we focus on the potential for implementation in routine laboratories, which we consider as the next step for liquid-phase microextraction.

Dispersive liquid-liquid extraction based on magnetic Pickering emulsion followed by gas chromatography-tandem mass spectrometry for the simultaneous determination of aldehydes in environmental water samples

A dispersive liquid-liquid extraction based on Pickering emulsion stabilized with ferroferric oxide grafted nitrogen-doped graphitized carbon black has been developed to simultaneously determine seven aldehydes in environmental water samples, in combination with pentafluorobenzyl hydroxylamine precolumn derivatization gas chromatography-tandem mass spectrometry. The nitrogen-doped graphitized carbon was prepared from dicyandiamide waste residue with a simple acid wash process. The effects of magnetic emulsifier amount, extraction time, solution pH, and oil/water volume ratio on the formation of magnetically responsive Pickering emulsion and the extraction efficiency of the proposed dispersive liquid-liquid extraction were also investigated. Under the optimized conditions, satisfactory linearities were obtained for all aldehydes with correlation coefficients larger than 0.9984. The limits of detection and quantitation of seven aldehydes were in the range of 17.3-30.1 ng/L and 54.3-103.4 ng/L, respectively, with intra- and interday relative standard deviations less than 8.6%. The mean recoveries at three spiked levels ranged from 70.0 to 101.4%. With the Pickering emulsion as a "minimized extractor", the extraction was accomplished within 5 min. After extraction, the magnetic disperser could be recovered for reuse at least five times by an external magnetic field. The proposed method was demonstrated to be feasible, simple, and economic for the trace analysis of the aldehydes in environmental water samples.

Hydrophilic interaction chromatography combined with ultrasound-assisted ionic liquid dispersive liquid-liquid microextraction for determination of underivatized neurotransmitters in dementia patients' urine samples

A sensitive, rapid, precise and specific analytical method of hydrophilic interaction ultra-performance liquid chromatography coupled with triple-quadrupole linear ion-trap tandem mass spectrometry (HILIC-UHPLC-QTRAP®/MS²) combined with a high-efficiency and easy sample preparation technology of ultrasound-assisted ionic liquid dispersive liquid-liquid microextraction (UA-IL-DLLME) was developed to investigate neurotransmitters (NTs) in mild cognitive impairment, mild dementia and moderate dementia patients' urine samples. Firstly, the UA-IL-DLLME parameters were optimized using Plackett-Burman screening and rotatable central composite design, and the main optimal conditions were obtained: ultrasound power of 307 W, ultrasound time of 4.3 min and agitation time of 4.8 min. Secondly, HILIC-UHPLC-QTRAP®/MS² method was developed to simultaneously determine 15 underivatized NTs in urine samples. The analysis results of clinical samples showed that some NTs such as γ-aminobutyric acid (GABA), acetylcholine (Ach) and glutamic acid (Glu) presented significant differences in different dementia stages. Finally, multivariate analysis based on the combination of principal component analysis and supervised counter propagation artificial neural network was developed for comprehensive analysis of the obtained clinical data sets. As a result, GABA and Glu were simultaneously presented meaningful contribution for classification of samples, and might be considered as potential differential compounds to the urine samples from cluster patients with different dementia stages. In summary, the presented strategy of preparation, analysis and statistics might be used to investigate NTs in different clinical biological fluids.

Sequence-specific preconcentration of a mutation prone KRAS fragment from plasma using ion-tagged oligonucleotides coupled to qPCR compatible magnetic ionic liquid solvents

Circulating tumor DNA (ctDNA) is a source of mutant DNA found in plasma and holds great promise in guiding cancer diagnostics, prognostics, and treatment. However, ctDNA fragments are challenging to detect in plasma due to their low abundance compared to wild-type DNA. In this study, a series of ion-tagged oligonucleotides (ITO) were synthesized using thiol-ene click chemistry and designed to selectively anneal target DNA. The ITO-DNA duplex was subsequently captured using a hydrophobic magnetic ionic liquid (MIL) as a liquid support. Extracted target DNA was quantified by adding the DNA-enriched MIL to the quantitative polymerase chain reaction (qPCR) buffer to streamline the extraction procedure. Clinically relevant concentrations of the mutation prone KRAS fragment, which has been linked to colorectal, lung, and bladder cancer, were preconcentrated using the ITO-MIL strategy allowing for enrichment factors as high as 19.49 ± 1.44 from pure water and 4.02 ± 0.50 from 10-fold diluted plasma after a 1 min extraction. Preconcentration could only be achieved when adding the ITO probe to the sample validating the selectivity of the ITO in the capture process. In addition, the amplification efficiency of qPCR was not affected when performing extractions from a diluted-plasma matrix demonstrating that the ITO-MIL approach coupled to direct-qPCR can be used to quantitate DNA from complex matrices. In comparison, commercially available steptavidin-coated magnetic beads were observed to lose selectivity when performing extractions from a 10-fold diluted plasma matrix. The selectivity of the ITO-MIL method, coupled with the ability to rapidly preconcentrate clinically relevant concentrations of target DNA from 10-fold diluted plasma, suggests that this method has the potential to be applied towards the extraction of ctDNA fragments from clinical samples.

Recent Advances and New Perspectives in Capillary Electrophoresis-Mass Spectrometry for Single Cell "Omics"

Accurate clinical therapeutics rely on understanding the metabolic responses of individual cells. However, the high level of heterogeneity between cells means that simply sampling from large populations of cells is not necessarily a reliable approximation of an individual cell's response. As a result, there have been numerous developments in the field of single-cell analysis to address this lack of knowledge. Many of these developments have focused on the coupling of capillary electrophoresis (CE), a separation technique with low sample consumption and high resolving power, and mass spectrometry (MS), a sensitive detection method for interrogating all ions in a sample in a single analysis. In recent years, there have been many notable advancements at each step of the single-cell CE-MS analysis workflow, including sampling, manipulation, separation, and MS analysis. In each of these areas, the combined improvements in analytical instrumentation and achievements of numerous researchers have served to drive the field forward to new frontiers. Consequently, notable biological discoveries have been made possible by the implementation of these methods. Although there is still room in the field for numerous further advances, researchers have effectively minimized various limitations in detection of analytes, and it is expected that there will be many more developments in the near future.