Parkinson's disease (PD) is the second most prevalent neurodegenerative disorder, and diagnosis typically occurs after substantial neuronal loss, underscoring the need for biomarkers capable of detecting early pathological changes. The endocannabinoids anandamide (AEA) and 2-arachidonoylglycerol (2-AG) have been proposed as potential PD biomarkers; however, only their free fractions are biologically active. In this study, an in vivo solid-phase microextraction (SPME) method was developed to quantify free and total concentrations of AEA and 2-AG in rat brain under conditions of negligible depletion. Under these conditions, the SPME probe functions analogously to a sensor, extracting only minute amounts of analyte without perturbing the equilibrium between free and matrix-bound species. Extractions were performed at equilibrium, and experimentally determined distribution constants in PBS were used to calculate free concentrations. Matrix-binding percentages exceeded 99% for both analytes and were used alongside with free concentration measurements to estimate total concentration levels. In vivo analyses in a 6-OHDA rat model of PD revealed significant elevated striatal AEA levels in lesioned animals relative to controls, supporting its potential as a biomarker of early neurochemical alterations. In contrast, ex vivo SPME extractions in dissected brain did not show increased AEA levels in the PD group, indicating loss of physiologically relevant information post-mortem. Although 2-AG was not detected in vivo, it was quantified ex vivo, suggesting limited active release under the examined conditions. Overall, these findings highlight the capability of in vivo SPME to capture changes in heavily bound hydrophobic neurochemicals, thereby supporting its application in studies of endocannabinoid dysregulation.

BACKGROUND:Reliable quantification of amyloid-β (Aβ) peptides in biological fluids is of major clinical and research interest in Alzheimer disease context. Conventional offline extraction approaches often involve labor-intensive manual steps and high solvent consumption, limiting throughput routine applications, reproducibility, and sustainability. To address these limitations, this study reports the development of an online coupling between a monolithic oligosorbent (mOS) in capillary and high-performance liquid chromatography-mass spectrometry (HPLC-MS) method for selective Aβ peptide analysis. RESULTS:A mOS was incorporated online in a set up including a C18 trap column coupled with an HPLC-MS analytical system. Systematic optimization of mOS loading/elution conditions, trapping column desalting/preconcentration, and chromatographic mobile phase composition enabled efficient retention, transfer, and separation of Aβ40 and Aβ42 in a fully automated method. This method achieved lower limits of quantification down to 0.03 ng mL-1 with good precision and accuracy (CV ranging from 1.1 to 6.2% for Aβ40 and from 4.3 to 10.9% for Aβ42). Comparative evaluation of offline and online extraction using the same mOS capillary demonstrated improved reproducibility and enhanced sensitivity for the online configuration. The method's applicability to a controlled CSF-like matrix was demonstrated using artificial cerebrospinal fluid (aCSF) diluted 1:2 (v/v) in binding buffer (BB), yielding recoveries of 60% for Aβ40 and 34% for Aβ42. SIGNIFICANCE:The online coupling of the mOS capillary with HPLC-MS also represents a strategic advance toward environmentally responsible bioanalysis. Indeed, the superior AGREEprep score (0.7) for the online configuration compared to offline mode (0.59), underscores its alignment with green analytical chemistry principles, reflecting reductions in solvent use, manual intervention, and overall environmental burden.

The ratio between beta-amyloid (Aβ) peptides 40 and 42 is recognized as a biomarker for Alzheimer's disease, playing a significant role in early diagnosis and disease progression monitoring. Aβ peptides are present at trace levels in cerebrospinal fluid, therefore, developing a new selective extraction procedure is essential for isolating targeted biomarkers from the matrix interferents, ensuring accurate identification and quantification. In this study, a hybrid organic-silica monolith was synthesized in a 530 µm inner diameter-capillary and used for the covalent grafting of beta amyloid peptide aptamers. The resulting miniaturized oligosorbent (mOS) was applied to selectively extract Aβ peptides 40 and 42 from artificial cerebrospinal fluid (CSF) samples. The immobilization procedure achieved grafting yields higher than 90

BACKGROUND:High circulating concentrations of homocysteine (Hcy), a sulfur-containing amino acid, and homocysteic acid (HCA), an Hcy oxidized derivative, are an independent risk factor for developing Alzheimer's disease (AD), a neurodegenerative disorder that causes progressive cognitive decline. Therefore, these two endogenous compounds might be potential AD biomarkers. Nevertheless, few studies have attempted to quantify Hcy and HCA in the cerebrospinal fluid (CSF), the best validated fluid for evaluating neurodegenerative disorders. RESULTS:Here, a novel restricted access-anion exchange organic monolithic phase was synthetized and used as extractive phase during in-tube SPME to analyze Hcy and HCA in CSF samples by LC-MS/MS. The innovative monolithic sorbent is porous and permeable, bears anion exchange groups that selectively extract the target analytes, and displays hydrophilic groups that restrict the access and exclude up to 90 % of macromolecules. Optimization of the synthesis parameters and evaluation of the in-tube SPME parameters improved the monolithic phase efficiency in extracting Hcy and HCA. Validation of the proposed method showed that it is linear from 8 to 250 ng mL-1 Hcy and from 5 to 150 ng mL-1 HCA, has adequate accuracy and precision, no significant matrix effect, and prevents carryover. Application of this innovative method to analyze CSF samples obtained from patients with AD, patients with mild cognitive impairment (MCI), or healthy controls revealed elevated Hcy levels in AD and MCI patients, with considerable discriminatory potential. SIGNIFICANCE AND NOVELTY:This is the first organic monolith with restricted access-anion exchange properties to be developed for in-tube SPME application. Furthermore, the proposed method addresses the need of a robust microextraction method for the determination of Hcy and HCA in cerebrospinal fluid samples. The findings also suggest Hcy as a potential AD biomarker, motivating further studies on the role this endogenous compound plays in early diagnosis and disease progression.

Alzheimer’s disease (AD) is a neurodegenerative disorder characterized by extracellular accumulation of amyloid-β (Aβ) peptides in the brain. This study demonstrates the direct association of the disposable pipette extraction (DPX) with tandem mass spectrometry (MS/MS) for the analysis of Aβ peptides in cerebrospinal fluid (CSF) samples. Different parameters were optimized in order to improve detectability in the MS/MS including mobile phase percentage of ammonium hydroxide, mobile phase flow rate and acquisition mode. Also, this method used an electrospray ionization (ESI) low-flow probe and direct infusion of an organic solution in the MS/MS. The DPX-MS/MS method showed adequate linearity for determining Aβ peptides in CSF-linearity ranged from 0.1 to 1.5 ng mL-1. The coefficients of determination were higher than 0.99; the precision coefficient of variation (CV) ranged from 0.3 to 12.7%; and the accuracy relative standard deviation (RSD) ranged from -13.6 to 13.2%.

Despite the widespread use of L-3,4-dihydroxyphenylalanine (L-DOPA) as the gold standard for dopamine (DA) replacement in Parkinson's Disease (PD), its prolonged administration frequently leads to L-DOPA-induced dyskinesia (LID), a significant therapeutic challenge. Modulating the endocannabinoid system has emerged as a promising approach for managing LID. This study explored whether cannabidiol (CBD), a non-psychoactive compound of Cannabis sativa, and PECS-101, a fluorinated derivative of CBD, could mitigate the onset and progression of LID. We used unilateral 6-hydroxydopamine-lesioned rats, treated with L-DOPA (10 mg kg - 1) for three weeks to induce severe abnormal involuntary movements (AIMs). Treatments were administered during the final two weeks. CBD (30 mg kg - 1) and PECS-101 (3 and 30 mg kg - 1) significantly reduced AIMs without impairing the motor benefits of L-DOPA. The antidyskinetic effects of CBD were associated with decreased striatal Fos-B and phospho-ERK expression and were independent of lesion severity. CBD effects were prevented by antagonists of CB1 (1 mg kg - 1) and PPARγ (4 mg kg - 1) receptors. Co-administration of TRPV-1 antagonist capsazepine (5 mg kg - 1) enhanced the antidyskinetic effects of CBD. Combining the capsazepine with the neuronal nitric oxide synthase inhibitor, 7-nitroimidazole (10 mg kg - 1) enhanced these effects. CBD did not alter striatal DA levels but significantly increased the concentrations of anandamide and 2-arachidonoylglycerol in dyskinetic animals. The antidyskinetic effects of CBD were associated with a reduction of the enhanced striatal glia and peripheral inflammation markers. These findings suggest that CBD alleviates LID by interacting with the nitrergic neurotransmission and TRPV-1, CB1, and PPARγ receptors.

ABSTRACTCannabidiol (CBD) and Δ9‐tetrahydrocannabinol (THC), the main components of Cannabis sativa plants, can interact with specific cell receptors known as cannabinoid receptors (CBs). The endogenous compounds anandamide (AEA) and 2‐arachidonoylglycerol (2‐AG) are CB agonists, and, alongside enzymes, they constitute the endocannabinoid system (ECS) and take part in neuromodulation. Several LC‐MS/MS methods have been developed to quantify these compounds in biological matrixes, but a fast and simple method that can determine these analytes in plasma samples simultaneously is not available. Here, we propose a disposable pipette extraction technique containing a zirconia‐based sorbent (DPX(Zr)) combined with UHPLC‐MS/MS analysis to determine CBD, THC, AEA, and 2‐AG in plasma samples, simultaneously. The method combines simple protein precipitation (PPT) with a one‐step DPX procedure to remove phospholipids, one of the most common endogenous interferents in biological samples. Optimization of the combined PPT‐DPX sample preparation method reduced the matrix effect and improved the sensitivity of the analytical method. The validated DPX(Zr)‐UHPLC‐MS/MS method reported LLOQs of 0.1 ng mL−1 for AEA and 2‐AG and 1 ng mL−1 for CBD and THC. The method demonstrated intra‐ and interassay accuracy and precision of less than 20% for the LLOQ, and less than 15% for the other calibration points. Additionally, no carryover or significant matrix effect was observed. We applied this method to determine AEA, 2‐AG, and CBD in plasma samples obtained from obsessive‐compulsive disorder patients treated with CBD.

Cannabidiol (CBD) and Δ9-tetrahydrocannabinol (THC) are the primary compounds of interest in the plant cannabis sativa, used mainly as recreational drug. Since THC, CBD, and other cannabinoids were discovered, they have been investigated as potential therapeutic agents for numerous pathologies, including neurodegenerative disorders, cancer, pain, inflammation, and autoimmune conditions. In this context, developing chromatographic analytical methods to determine THC, CBD, their metabolites, and other cannabinoids in biological samples is essential in the forensic field, to detect illicit use of cannabis, and medical field, to prospect pharmaceutical applications of cannabinoids and cannabis-based products. Because biological matrixes are complex, these compounds cannot be directly analyzed on chromatographic systems, and a sample preparation step is required. In this step, an extraction technique is used to exclude interfering molecules while selectively extracting and pre-concentrating the target analytes, often present at trace levels in biological samples. This paper reviews the chromatographic methods published over the past two years and highlights sample preparation. Special focus is placed on state-of-the-art sample preparation techniques aimed at determining CBD, THC, and their metabolites. Moreover, this review discusses fundamentals, details, pros and cons, and intrinsic parameters of classic, conventional sample preparation techniques as well as modern, miniaturized, and microextraction techniques. Additionally, this review covers the reported biological matrixes, instrumentation, and applications.

Higher serum cortisol levels appear to be associated with stress that can overlap or manifest anxiety, fatigue, depression, and sleep dysfunction. These are common and intrusive non-motor symptoms of Parkinson’s disease (PD). Thus, stress has been proposed to mediate Parkinson’s disease development, and cortisol has been suggested as a biomarker for the generation of stress-related symptoms in Parkinson’s disease. This study describes sensitive and robust disposable pipette extraction (DPX) and ultra-efficient liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) method to determine cortisol and cortisone (as potential endocrine biomarkers for Parkinson’s disease) in 24-h urine and saliva samples obtained from Parkinson’s disease patients. Important parameters on DPX extraction were optimized to achieve the best extraction recovery and cleanup efficiency. The proposed method was linear from 0.5 (lower limit of quantification) to 500 ng mL−1 for cortisol and from 3.0 (lower limit of quantification) to 500 ng mL−1 for cortisone. To determine whether urinary cortisol and urinary cortisone are adequate as biomarkers to evaluate the level of anxiety in patients suffering from Parkinson’s disease, twenty-nine Parkinson’s disease patients (18 with anxiety and 11 without anxiety) were selected for urine analysis. Based on the obtained results, 24-h urine samples obtained from Parkinson’s disease patients with anxiety had higher cortisone levels than samples obtained from healthy controls. Receiving operating curves (ROC) analysis, which presented the area under the ROC curve (AUC = 0.733), showed that urinary cortisone levels (µg/24-h urine) were sensitive (56.3

Mass spectrometry (MS/MS) is characterized by its high sensitivity, ability to measure very low analyte concentrations, specificity to distinguish between closely related compounds, availability to generate high-throughput methods for screening, and high multiplexing capacity. This technique has been used as a platform to analyze fluid biomarkers for Alzheimer's disease (AD). However, more effective sample preparation procedures, preferably antibody-independent, and more automated MS/MS platforms with improved sensitivity, LC separation, and high throughput are needed for this purpose. This short communication discusses the development of a fiber-in-tube SPME-CapLC-MS/MS method to determine Aβ peptides in cerebrospinal fluid (CSF) obtained from AD patients. To obtain the fiber-in-tube SPME capillary, we longitudinally packed 22 nitinol fibers coated with a zwitterionic polymeric ionic liquid into the same length of the PEEK tube. In addition, this communication compares this fiber-in-tube SPME method with the conventional LC scale (LC-MS/MS) and when directly coupled to CapESI-MS/MS without chromatographic separation, and, as a case study, discusses the benefits and challenges inherent in miniaturizing the flow scale of the sample preparation technique (fiber-in-tube SPME) to the CapLC-MS/MS system. Fiber-in-tube SPME-CapLC-MS/MS provided LLOQ ranging from 0.09 to 0.10 ng mL−1, accuracy ranging from 91 to 117% (recovery), and reproducibility of less than 18 % (RSD). Analysis of the CSF samples obtained from AD patients evidenced that the method is robust. At the capillary scale (10 µL min−1), this innovative method presented higher analytical sensitivity than the conventional HPLC-MS/MS scale. Although fiber-in-tube SPME directly coupled to CapESI-MS/MS offers advantages in terms of high throughput, the sample was dispersed and non-quantitatively desorbed from the capillary at low flow rate. These results highlighted that chromatographic separation is important to decrease the matrix effect and to achieve higher detectability, which is indispensable for bioanalysis.

Organic-silica hybrid monolithic materials have attracted considerable attention as potential stationary phases in separation science. These materials combine the advantages of organic polymer and silica-based monoliths, including easy preparation, lower back pressure, high permeability, excellent mechanical strength, thermal stability, and tunable surface chemistry with high surface area and selectivity. The outstanding chromatographic efficiency as stationary phase of hybrid monolithic capillary columns for capillary liquid chromatography and capillary electrochromatography has been reported in many papers. Organic-silica hybrid monolithic materials have also been extensively used in the field of sample preparation. Owing to their surface functionalities, these porous sorbents offer unique selectivity for pre-concentration of different analytes in the most complex matrixes by fast dynamic transport. These sorbents not only improve the analytical method sensitivity, but also introduce novelties in terms of extraction devices and instrument coupling strategies. The current review covers the period spanning from 2017 to 2023 and describes the properties of organic-inorganic hybrid monolithic materials, the present status of this technology and summarizes recent developments in their use as innovative sorbents for microextraction sample preparation techniques (solid phase microextraction with pipette tip, offline in-tube SPME, in-tube SPME online with LC, and in-tube SPME directly coupled with mass spectrometry). Aspects such as the synthesis methods (sol-gel process, one-pot approach, and polyhedral oligomeric silsesquioxanes-based procedure), characterization techniques, and strategies to improve extraction efficiency in various applications in different areas (environmental, food, bioanalysis, and proteomics) are also discussed.

In this study, we present a novel combination of carbon nanotubes (CNT), widely used as a sorbent material in solid-phase extraction-based methodologies, with polybenzimidazole (PBI), recently introduced as a universal binder for physical immobilization of sorbent particles. This combination was used to prepare CNT-PBI coated solid-phase microextraction (SPME) devices (fibers, arrows, and blades) suitable for both thermal and solvent desorption. The resulting CNT-PBI SPME devices presented excellent mechanical resistance and high thermal stability, capable of enduring multiple thermal desorption cycles without compromising extraction efficiency. They also demonstrated stability in a range of organic solvents commonly used for solvent desorption, with no swelling or shrinkage observed. We evaluated the performance of the CNT-PBI fibers in gas chromatography-mass spectrometry (GC-MS) analysis of BTEX (benzene, toluene, ethylbenzene and xylene) compounds, comparing them to carboxen/polydimethylsiloxane (CAR-PDMS) and CAR-PBI fibers. The CNT-PBI fibers showed superior extraction efficiency for benzene, toluene, and xylene. In liquid chromatography-mass spectrometry (LC-MS) analysis of drugs of abuse, CNT-PBI blades outperformed CNT blades prepared with a conventional polyacrylonitrile (PAN) binder in extracting non-polar drugs (log P > 2.8). Moreover, CNT-PBI blades demonstrated similar extraction performance to C18-PBI blades, considering the differences in particle-to-binder ratio and the coating thickness of each material. Comparing the extraction performance between CNT-PBI and CNT-PAN blades for liquid chromatography-high resolution mass spectrometry (LC-HRMS) untargeted analysis in water samples revealed that the binders (PBI and PAN) significantly influenced the sorption capabilities of the coating particles. These findings highlight the potential of solvent and thermally stable CNT-PBI devices for SPME in both GC and LC analyses.

Current research efforts at neurological diseases have focused on identifying novel biomarkers to aid in diag-nosis, to provide accurate prognostic information, and to monitor disease progression. This study presents the direct coupling of fiber-in-tube solid-phase microextraction to tandem mass spectrometry as a reliable method to determine amyloid beta peptides (A beta 38, A beta 40, and A beta 42) as biomarkers for Alzheimer's disease in cerebrospinal fluid (CSF) samples. To obtain the biocompatible fiber-in-tube SPME capillary, a PEEK tube segment was longi-tudinally packed with fine fibers [nitinol wires coated with a zwitterionic polymeric ionic liquid], to act as se-lective extraction medium. The fiber-in-tube SPME-MS/MS method integrated analyte extraction/enrichment and sample cleanup (exclusion of interferents) into one step. The method provided lower limits of quantification (LLOQ: 0.2 ng mL-1 for A beta 38 and 0.1 ng mL-1 for A beta 40 and A beta 42), high precision (CV lower than 11.6%), and high accuracy (relative standard deviation lower than 15.1%). This method was successfully applied to deter-mine A beta peptides in CSF samples obtained from AD patients (n = 8) and controls (healthy volunteers, n = 10). Results showed that A beta 42 levels in the CSF samples obtained from AD patients were significantly lower compared to healthy controls (p < 0.05). On the basis of the ROC analysis results, the A beta 42/A beta 40 ratio (AUC = 0.950, p < 0.01; 95%) performed significantly better than A beta 42 alone (AUC = 0.913, p < 0.01; 95%) in discriminating between AD patients and healthy controls and presented better diagnostic ability for AD. The novelties of this study are not only related to evaluating A beta peptides as AD biomarkers, but also to demonstrating direct online coupling of fiber-in-tube SPME with MS/MS as a quantitative high-throughput method for bioanalysis.

Abstract Background Serotonergic hallucinogens and cannabinoids may alter the recognition of emotions in facial expressions (REFE). Cannabidiol (CBD) attenuates the psychoactive effects of the cannabinoid-1 agonist tetrahydrocannabinol. Ayahuasca is a dimethyltryptamine-containing hallucinogenic decoction. It is unknown if CBD may moderate and attenuate the effects of ayahuasca on REFE. Procedures Seventeen healthy volunteers participated in a 1-week preliminary parallel-arm, randomized controlled trial for 18 months. Volunteers received a placebo or 600 mg of oral CBD followed by oral ayahuasca (1 mL/kg) 90 minutes later. Primary outcomes included REFE and empathy tasks (coprimary outcome). Tasks were performed at baseline and 6.5 hours, 1 and 7 days after the interventions. Secondary outcome measures included subjective effects, tolerability, and biochemical assessments. Results Significant reductions (all P values <0.05) only in reaction times were observed in the 2 tasks in both groups, without between-group differences. Furthermore, significant reductions in anxiety, sedation, cognitive deterioration, and discomfort were observed in both groups, without between-group differences. Ayahuasca, with or without CBD, was well tolerated, producing mainly nausea and gastrointestinal discomfort. No clinically significant effects were observed on cardiovascular measurements and liver enzymes. Conclusions There was no evidence of interactive effects between ayahuasca and CBD. The safety of separate and concomitant drug intake suggests that both drugs could be applied to clinical populations with anxiety disorders and in further trials with larger samples to confirm findings.

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by an extracellular accumulation of amyloid beta peptides in the brain. The concentration of the amyloid beta peptides in cerebrospinal fluid (CSF) have been evaluated as potential biomarkers of AD for early diagnostic. In this work, an in-tube solid-phase microextraction (in-tube SPME) coupled to UHPLC-MS/MS method was established to determine amyloid beta peptides in CSF samples from AD patients. A strong cation-exchange (sulfopropyl methacrylate-co-ethylene glycol dimethacrylate) monolithic capillary was synthesized on the inner surface of a fused silica capillary and used as an extractive phase for in-tube SPME. The morphology and chemical structure of the monolithic phase were characterized by scanning electron microscopy and Fourier transform infrared spectroscopy. The proposed method presented linear range from the lower limits of quantification 0.6 and 0.8 to 10 ng mL(-1). Excluding the lower limits of quantification values, the analytical validation showed precision with the coefficient of variation values lower than 13.1%, and accuracy with relative standard deviation lower than 13.5%. The in-tube SPME coupled to UHPLC-MS/MS method was successfully applied to determine amyloid beta peptides in CSF samples from AD patients.

Liquid chromatography-tandem mass spectrometry (LC-MS/MS) has become the reference technique for bioanalysis, due to its high sensitivity and selectivity. In bioanalysis, a sample preparation step is usually necessary to eliminate most endogenous compounds and to concentrate the target analytes that often exist at trace levels in biological matrixes. Recent trends in biological sample preparation have focused on miniaturized systems, the development of selective new sorbent materials, and high throughput performance with online coupling to analytical instruments. A miniaturized system requires a smaller amount of sample and organic solvents, and an online system reduces the sample preparation steps, analysis time, and costs and improves accuracy. In this context, online capillary solid-phase microextraction (in-tube SPME) coupled to LC systems is worth mentioning. This technique uses a capillary column as the extraction device and enables continuous extraction, concentration, and desorption online with LC systems. This chapter describes the principle of in-tube SPME-LC, configurations, optimization of parameters, new stationary phases, bioanalysis application, and the present state of this technique and summarizes current trends and future perspectives.

Pheromones are essential for colony organization in honeybees. The pheromones 9-ODA ((E)-9-oxodec-2-enoic acid) and 9-HDA ((E)-9-hydroxydec-2-enoic acid), produced by the mandibular gland of the queen, have various functions within the colony, including inhibition of ovarian development of workers, attraction of swarms, and stabilization of the cluster group. An example of reaction of the colony to adverse conditions is absconding, which is defined as mass exit of all of the adult individuals, leaving even brood and food. In this study, the pheromones 9-ODA and 9-HDA were determined in virgin and normal mated, egg-laying European Carniolan and Africanized queens, as well as in mated queens that were in absconding colonies, using liquid chromatography with UV detection developed methodology. Absconding was induced by maintaining free-flying five-standard-Langstroth-frame colonies in a chamber artificially heated to 45 ºC. The obtained results showed that the amount of 9-ODA in Africanized queens (6.56 µg bee-1 ) is very low compared with European queens. However, large amounts of 9-HDA were found in the queens of absconding Africanized swarms (107.4 µg bee-1). According to our results, the quantities of 9-ODA and 9-HDA in Africanized honeybees in Brazil may be contributing to the high rates of absconding, promoting low effect of stabilizing agent, and high effect of attraction of dispersers cluster.

Alzheimer’s disease (AD), a neurological disorder, is a major public health concern and the most common form of dementia. Its typical symptoms include memory loss, confusion, changes in personality, and cognitive impairment, which result in patients gradually losing independence. Over the last decades, some studies have focused on searching for effective biomarkers as early diagnostic indicators of AD. Amyloid-β (Aβ) peptides have been consolidated as reliable AD biomarkers and have been incorporated into modern diagnostic research criteria. However, quantitative analysis of Aβ peptides in biological samples remains a challenge because both the sample and the physical–chemical properties of these peptides are complex. During clinical routine, Aβ peptides are measured in the cerebrospinal fluid by immunoassays, but the availability of a specific antibody is critical—in some cases, an antibody may not exist, or its specificity may be inadequate, leading to low sensitivity and false results. HPLC-MS/MS has been reported as a sensitive and selective method for determining different fragments of Aβ peptides in biological samples simultaneously. Developments in sample preparation techniques (preconcentration platforms) such as immunoprecipitation, 96-well plate SPME, online SPME, and fiber-in-tube SPME have enabled not only effective enrichment of Aβ peptides present at trace levels in biological samples, but also efficient exclusion of interferents from the sample matrix (sample cleanup). This high extraction efficiency has provided MS platforms with higher sensitivity. Recently, methods affording LLOQ values as low as 5 pg mL−1 have been reported. Such low LLOQ values are adequate for quantifying Aβ peptides in complex matrixes including cerebrospinal fluid (CSF) and plasma samples. This review summarizes the advances in mass spectrometry (MS)-based methods for quantifying Aβ peptides and covers the period 1992–2022. Important considerations regarding the development of the HPLC-MS/MS method such as the sample preparation step, optimization of the HPLC-MS/MS parameters, and matrix effects are described. Clinical applications, difficulties related to analysis of plasma samples, and future trends of these MS/MS-based methods are also discussed.

BackgroundSerotonergic hallucinogens and cannabinoids may alter the recognition of emotions in facial expressions (REFE). Cannabidiol (CBD) attenuates the psychoactive effects of the cannabinoid-1 agonist tetrahydrocannabinol. Ayahuasca is a dimethyltryptamine-containing hallucinogenic decoction. It is unknown if CBD may moderate and attenuate the effects of ayahuasca on REFE.ProceduresSeventeen healthy volunteers participated in a 1-week preliminary parallel-arm, randomized controlled trial for 18 months. Volunteers received a placebo or 600 mg of oral CBD followed by oral ayahuasca (1 mL/kg) 90 minutes later. Primary outcomes included REFE and empathy tasks (coprimary outcome). Tasks were performed at baseline and 6.5 hours, 1 and 7 days after the interventions. Secondary outcome measures included subjective effects, tolerability, and biochemical assessments.ResultsSignificant reductions (all P values <0.05) only in reaction times were observed in the 2 tasks in both groups, without between-group differences. Furthermore, significant reductions in anxiety, sedation, cognitive deterioration, and discomfort were observed in both groups, without between-group differences. Ayahuasca, with or without CBD, was well tolerated, producing mainly nausea and gastrointestinal discomfort. No clinically significant effects were observed on cardiovascular measurements and liver enzymes.ConclusionsThere was no evidence of interactive effects between ayahuasca and CBD. The safety of separate and concomitant drug intake suggests that both drugs could be applied to clinical populations with anxiety disorders and in further trials with larger samples to confirm findings.