Concentrations In Biological Samples Research Articles

Therapeutic Drug Monitoring in Psychiatry: Enhancing Treatment Precision and Patient Outcomes.

Psychiatric disorders often require pharmacological interventions to alleviate symptoms and improve quality of life. However, achieving an optimal therapeutic outcome is challenging due to several factors, including variability in the individual response, inter-individual differences in drug metabolism, and drug interactions in polytherapy. Therapeutic drug monitoring (TDM), by measuring drug concentrations in biological samples, represents a valuable tool to address these challenges, by tailoring medication regimens to each individual. This review analyzes the current landscape of TDM in psychiatric practice, highlighting its significance in optimizing drug dosages, minimizing adverse effects, and improving therapeutic efficacy. The metabolism of psychiatric medications (i.e., mood stabilizers, antipsychotics, antidepressants) often exhibits significant inter-patient variability. TDM can help address this variability by enhancing treatment personalization, facilitating early suboptimal- or toxic-level detection, and allowing for timely interventions to prevent treatment failure or adverse effects. Furthermore, this review briefly discusses technological advancements and analytical methods supporting the implementation of TDM in psychiatric settings. These innovations enable quick and cost-effective drug concentration measurements, fostering the widespread adoption of TDM as a routine practice in psychiatric care. In conclusion, the integration of TDM in psychiatry can improve treatment outcomes by individualizing medication regimens within the so-called precision medicine.

Newly Synthesized Reagent [TREN 3 (2 Quinoline)] for Determination of Nickel (II) in Biological Samples by Extractive-Differential Pulse Polarography

Abstract: The synthesis and application of a novel analytical reagent, [TREN 3 (2 Quinoline)], was detailed for the precise determination of nickel (II) concentrations in biological samples and plant materials. The analysis involved extracting the nickel(II)-TREN3(2Quinoline) complex from chloroform before injection into the instrument. To ensure accuracy and various parameters such as pH, pulse amplitude, scan rate, and choice of solvent were meticulously optimized. A calibration curve constructed in the concentration range from 0.05 to 42 µg mL-1 under pH 4.0, conditions using an acetate buffer, exhibiting a high correlation coefficient of 0.992. The study also thoroughly investigated potential interference from diverse ions, Validation of the proposed method was conducted using Certified Reference Materials provided by the National Institute of Standard Technology, affirming its accuracy and reliability. Furthermore, the reagent underwent characterization through techniques including infrared spectroscopy (IR), mass spectrometry (Mass), and elemental analysis, bolstering confidence in its suitability for analytical purposes.

Determination of L-selectin in blood plasma using DNA aptamer-based surface-enhanced Raman spectroscopy assay.

In the human body, tumor cell occurrence can be indirectly monitored using theL-selectin concentration in theblood, since selectin ligands are present on the surface of tumor cells, and with tumor progression, a decrease in L-selectin levels can be expected and observed. In this study, we present a selective DNA-based surface-enhanced Raman spectroscopy (SERS) assay for the detection and determination of L-selectin in biological samples. Two calibration curves (linear in the 40-190ngmL-1 region and exponential in the 40-500ngmL-1 region) are fitted to the obtained SERS experimental data, i.e., the ratio of I732/I1334 band intensities (LOQ = 46ngmL-1). Calculated determination coefficients are found to be R2 = 0.997 for the linear region of the calibration curve and R2 = 0.977 for the exponential region. Moreover, we demonstrate very good selectivity of theassay even in the presence of P- and E-selectin in a sample containing L-selectin. With our SERS assay, the L-selectin concentration in biological samples can be estimated directly from the calibration curves.

Comparison between Microwave Digestion and Conventional Open Digestion Method for Heavy Metals determination

In the present study a comparison between microwave assisted digestion and conventional wet acid open digestion system for dissolution of bivalve tissue samples was carried out. Sample matrix decomposition was done by using a mixture of concentrated nitric acid and hydrogen peroxide. The determination of trace elements (Zn, Co, Cu, Cd and Pb) in commercially popular bivalve species from two important fish landing centers in Mumbai was used for this purpose. The recovery of heavy metals after analysis was done using certified reference material TORT 2- Lobster hepatopancreas for both the digestion methods. The results of the present study indicate that microwave digestion system for heavy metal analysis is the preferred method for rapid and good quality results. It provides better recovery and precision for heavy metal analysis. The sample preparation step is much easier by microwave digestion system compared to conventional open digestion methods for heavy metal analysis. It is particularly ideal for trace metals like lead and cadmium as they are generally present in very small concentration in biological samples. In the current study microwave digestion proved to be better method than conventional open digestion method with rapid sample digestion process and least sample contamination problem.

Thallium - poisoner’s poison: An overview and review of current knowledge on the toxicological effects and mechanisms

Thallium (Tl) is one of the most toxic metals and its historic use in homicides has led it to be known as “the poisoner’s poison.” This review summarizes the methods for identifying Tl and determining its concentrations in biological samples in recently reported poisoning cases, as well as the toxicokinetics, toxicological effects, toxicity mechanisms, and detoxication methods of Tl. Recent findings regarding Tl neurotoxicological pathways and toxicological effects of Tl during pregnancy are also presented. Confirmation of elevated Tl concentrations in blood, urine, or hair is indispensable for diagnosing Tl poisoning. The kidneys show the highest Tl concentration within 24 h after ingestion, while the brain shows the highest concentration thereafter. Tl has a very slow excretion rate due to its large distribution volume. Following acute exposure, gastrointestinal symptoms are observed at an early stage, and neurological dysfunction is observed later: Tl causes the most severe damage in the central nervous system. Alopecia and Mees’ lines in the nails are observed within 1 month after Tl poisoning. The toxicological mechanism of Tl is considered to be interference of vital potassium-dependent processes with Tl+ because its ionic radius is similar to that of K+, as well as inhibition of enzyme reactions by the binding of Tl to -SH groups, which disturbs vital metabolic processes. Tl toxicity is also related to reactive oxygen species generation and mitochondrial dysfunction. Prussian blue is the most effective antidote, and metallothionein alone or in combination with Prussian blue was recently reported to have cytoprotective effects after Tl exposure. Because Tl poisoning cases are still reported, early determination of Tl in biological samples and treatment with an antidote are essential.

Method Validation for Quantification of PFOS and PFOA in Human Plasma and a Pilot Study in Blood Donors from Thai Red Cross Society.

Information regarding per- and polyfluorinated substances concentrations in biological samples from the Thai population was still lacking. A sensitive bioanalytical method was developed and validated for the quantification of perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) levels in human plasma. Simple protein precipitation and LC-MS/MS techniques were used with stable isotope internal standards of 13C8-PFOS and 13C8-PFOA. The validated method followed the ICH bioanalytical validation guideline, and the results showed good accuracy, precision, and reproducibility. The validated analytical method was then applied to determine PFOS and PFOA concentrations in 50 human plasma samples from the National Blood Center, Thai Red Cross Society. The concentrations were found to be in ranges of <0.91-6.27 ng/mL for PFOS and <0.49-2.72 ng/mL for PFOA. PFOS was also measured separately for its isomers, and the geometric means of the linear isomer (L-PFOS) and branched isomer (br-PFOS) in plasma samples were at 1.85 and 0.41 ng/mL, respectively. Both PFOS and PFOA concentrations were lower in comparison to previous reports from other countries. The present study showed the application of our reliable method to determine PFOS and PFOA in biological samples in order to monitor the human exposure of both chemicals in Thailand.

Signal Amplification for Detection of Nilutamide in Three-Dimensional Electrochemical Sensor Using Copper Metal–Organic Framework Decorated Carbon Nanofibers

The extensive use of antibiotics has rapidly spread antibiotic resistance, which poses significant health risks to humans. Unfortunately, despite this pressing issue, there is still a lack of a reliable on-site detection method for the residues of antibiotics, such as nilutamide (Nlu). Consequently, there is an urgent need to develop and perfect such a detection method to effectively monitor and control antibiotic residues. In this study, the hydrothermal development of copper-metal-organic framework (Cu-MOF) polyhedrons on the functionalized carbon nanofiber (f-CNF) matrix allowed for the detection of Nlu in biological liquids via a sensitive amperometry technique. Further electrochemical detection of Nlu took place with the cyclic voltammetry (CV) technique Cu-MOF/f-CNF. Analytical and spectroscopic approaches were used to confirm the successful synthesis of Cu-MOF/f-CNF. The prepared material was decorated on the surface of GCE and performed as an electrochemical Nlu sensor, with a broad linear range of 0.01 to 141.4 μM and 2 nM as a lower limit of detection. In addition, the composites had a large surface area and many dedicated sites, which improved electrocatalysis. In practical applications, Cu-MOF/f-CNF/GCE provides a novel strategy for improving electrochemical activity by measuring Nlu concentrations in biological samples.

A novel strategy for therapeutic drug monitoring: application of biosensors to quantify antimicrobials in biological matrices.

Over the past few years, therapeutic drug monitoring (TDM) has gained practical significance in antimicrobial precision therapy. Yet two categories of mainstream TDM techniques (chromatographic analysis and immunoassays) that are widely adopted nowadays retain certain inherent limitations. The use of biosensors, an innovative strategy for rapid evaluation of antimicrobial concentrations in biological samples, enables the implementation of point-of-care testing (POCT) and continuous monitoring, which may circumvent the constraints of conventional TDM and provide strong technological support for individualized antimicrobial treatment. This comprehensive review summarizes the investigations that have harnessed biosensors to detect antimicrobial drugs in biological matrices, provides insights into the performance and characteristics of each sensing form, and explores the feasibility of translating them into clinical practice. Furthermore, the future trends and obstacles to achieving POCT and continuous monitoring are discussed. More efforts are necessary to address the four key 'appropriateness' challenges to deploy biosensors in clinical practice, paving the way for personalized antimicrobial stewardship.

Simultaneous Assay of CA 72-4, CA 19-9, CEA and CA 125 in Biological Samples Using Needle Three-Dimensional Stochastic Microsensors.

Two-needle 3D stochastic microsensors based on boron- and nitrogen-decorated gra-phenes, modified with N-(2-mercapto-1H-benzo[d]imidazole-5-yl), were designed and used for the molecular recognition and quantification of CA 72-4, CA 19-9, CEA and CA 125 biomarkers in biological samples such as whole blood, urine, saliva and tumoral tissue. The NBGr-2 sensor yielded lower limits of determination. For CEA, the LOD was 4.10 × 10-15 s-1 g-1 mL, while for CA72-4, the LOD was 4.00 × 10-11 s-1 U-1 mL. When the NBGr-1 sensor was employed, the best results were obtained for CA12-5 and CA19-9, with values of LODs of 8.37 × 10-14 s-1 U-1 mL and 2.09 × 10-13 s-1 U-1 mL, respectively. High sensitivities were obtained when both sensors were employed. Broad linear concentration ranges favored their determination from very low to higher concentrations in biological samples, ranging from 8.37 × 10-14 to 8.37 × 103 s-1 U-1 mL for CA12-5 when using the NBGr-1 sensor, and from 4.10 × 10-15 to 2.00 × 10-7 s-1 g-1 mL for CEA when using the NBGr-2 sensor. Student's t-test showed that there was no significant difference between the results obtained utilizing the two microsensors for the screening tests, at a 99% confidence level, with the results obtained being lower than the tabulated values.

4D-printed needle panel meters coupled with enzymatic derivatization for reading urea and glucose concentrations in biological samples

On-site analytical techniques continue being developed with advances in modern technology. To demonstrate the applicability of four-dimensional printing (4DP) technologies in the direct fabrication of stimuli-responsive analytical devices for on-site determination of urea and glucose, we used digital light processing three-dimensional printing (3DP) and 2-carboxyethyl acrylate (CEA)–incorporated photocurable resins to fabricate all-in-one needle panel meters. When adding a sample having a value of pH above the pKa of CEA (ca. 4.6–5.0) into the fabricated needle panel meter, the [H+]-responsive layer of the needle, printed using the CEA-incorporated photocurable resins, swelled as a result of electrostatic repulsion among the dissociated carboxyl groups of the copolymer, leading to [H+]-dependent bending of the needle. When coupled with a derivatization reaction (urease-mediated hydrolysis of urea to decrease [H+]; glucose oxidase-mediated oxidization of glucose to increase [H+]), the bending of the needle allowed reliable quantification of urea or glucose when referencing pre-calibrated concentration scales. After method optimization, the method's detection limits for urea and glucose were 4.9 and 7.0 μM, respectively, within a working concentration range from 0.1 to 10 mM. We verified the reliability of this analytical method by determining the concentrations of urea and glucose in samples of human urine, fetal bovine serum, and rat plasma with spike analyses and comparing the results with those obtained using commercial assay kits. Our results confirm that 4DP technologies can allow the direct fabrication of stimuli-responsive devices for quantitative chemical analysis, and that they can advance the development and applicability of 3DP-enabling analytical methods.

Green Synthesis of Blue Light-Emitting Carbon Dots Using Tridax procumbens Leaves: Optical and Electrochemical Studies

We report the preparation of biocompatible blue emitting carbon dots (CDs) using Tridax procumbens (T. procumbens) leaf extract as a bio-source. A one-step hydrothermal method was employed to prepare highly effective photoluminescent CDs. As-synthesized CDs were characterized using Ultraviolet-visible spectroscopy (UV-visible), Photoluminescence (PL), Fourier transform infrared (FT-IR), transmission electron microscopy (TEM) and Confocal Raman spectroscopy techniques. In addition, the third-order optical nonlinearity of the prepared CDs was carried out using Z-scan technique with the help of continuous wave diode pumped Nd:YAG laser (532 nm). The nonlinear optical (NLO) susceptibility, nonlinear absorption coefficient and nonlinear refractive index were calculated. The synthesized CDs exhibited good excitation dependent properties. The CDs/Nafion modified glassy carbon electrode (CDs/Nf/GCE) was prepared and its electrochemical and catalytic properties were evaluated by using cyclic voltammetry (CV). The CDs/Nf/GCE exhibited high electrocatalytic activity for dopamine oxidation in physiological condition. This new CDs/Nf/GCE showed a linear range of Dopamine (DA) detection from 40 to 220 μM with the limit of detection (LOD) of 2.7 μM. The stability and reproducibility of the electrode were also investigated which indicated that this green synthesized CDs could be used for the development of electrochemical sensor to determine DA concentration in biological samples.

Minimally Invasive and Fast Diagnosis of Gastric Cancer Based on Maspin Levels in Different Biological Samples.

(1) Background: Human SERPINB5, commonly known as maspin, has diverse functions as a tumor suppressor. Maspin has a novel role in cell cycle control, and common variants were discovered to be associated with gastric cancer (GC). Maspin was proven to also affect the EMT and angiogenesis of gastric cancer cells via the ITGB1/FAK pathway. Information about the maspin concentrations correlated with different pathological features of the patients may facilitate the fast diagnosis and personalized treatment of patients. The novelty of this study is given by the correlations established for the maspin levels in different biological features and clinicopathological features. These correlations can be extremely useful for surgeons and oncologists. (2) Patients and methods: Patients with clinical and pathological features, given the small number of samples available for this study, were selected from the database of the project GRAPHSENSGASTROINTES, and used in accordance with the Ethics Committee approval nr. 32,647/2018 awarded by the County Emergency Hospital from Targu-Mures. Stochastic microsensors were used as new screening tools for the determination of the concentration of maspin in four types of samples: tumoral tissues, blood, saliva and urine. (3) Results: The results obtained using the stochastic sensors were correlated with those tabulated in the clinical and pathological database. A series of assumptions regarding the values and practice important features for surgeons and pathologists were made. (4) Conclusions: This study provided a few assumptions regarding the correlations between the values of maspin levels in the analyzed samples and the clinical and pathological features. These results may be useful as preoperative investigations in order to help surgeons localize, approximate and choose the best treatment. These correlations may facilitate minim invasive and fast diagnosis of gastric cancer based on reliable detection of maspin concentration in biological samples (tumoral tissues, blood, saliva and urine).

Validation of ELISA Test-system for Trastuzumab (Herceptin, Hertikad) quantitative determination in biological fluids

Relevance. Trastuzumab is the drug of choice for the HER2+ breast cancer treatment. To determine the trastuzumab pharmacodynamics in personalized therapy a validated bioanalytical method for measuring the concentration of the drug in biological fluids is required. The aim: creation and assessment of the suitability (validation) of a test system based on enzyme-linked immunosorbent assay (ELISA) for the quantitative determination of trastuzumab concentration in human serum/plasma. Materials and methods. The presented test system is a classic ELISA kit with a 96-well polystyrene plate, the wells of which are coated with monoclonal antibodies specific to trastuzumab, secondary goat antibodies to the Fc fragment conjugated with horseradish peroxidase (HRP), substrate solution — (3,5,3',5')-tetramethylbenzidine (TMB) and stop solution. Quality control solutions were prepared by diluting known concentrations of trastuzumab in blank serum. Results. In the course of the work the limit of detection (0.84 ng/ml) and the lower limit of quantitative determination (1.41 ng/ml) of trastuzumab in serum/plasma were established and the high selectivity of analyte determination in a multicomponent matrix was proved. The found average values of trastuzumab concentrations did not deviate from the nominal values by more than 14 % in the entire range of determined concentrations, the intraand interseries precision of the test system did not exceed 8%, and the total method error was 20.1 %. The demonstrated dilution linearity allows the assay to be used to analyze a wide range of trastuzumab concentrations in biological samples. The stability of the components of the test system is defined as at least 1 year under storage conditions. Conclusion. The presented ELISA test system complies with international validation requirements and it is suitable for practical use.

Surface enhanced Raman scattering active substrate based on hydrogel microspheres for pretreatment-free detection of glucose in biological samples

Determining glucose in biological samples is tedious and time-consuming due to sample pretreatment. The sample is usually pretreated to remove lipids, proteins, hemocytes and other sugars that interfere with glucose detection. A surface-enhanced Raman scattering (SERS) active substrate based on hydrogel microspheres has been developed to detect glucose in biological samples. Due to the specific catalytic action of glucose oxidase (GOX), the high selectivity of detection is guaranteed. The hydrogel substrate prepared by microfluidic droplets technology protects the silver nanoparticles from the surrounding environment and improves the stability and reproducibility of the assay. In addition, the hydrogel microspheres have size-adjustable pores that selectively allow small molecules to pass through. The pores block the entry of large molecules, such as impurities, enabling glucose detection through glucose oxidase etching without sample pretreatment. This hydrogel microsphere-SERS platform is highly sensitive and enables reproducible detection of different glucose concentrations in biological samples. The use of SERS to detect glucose provides clinicians with new diagnostic methods for diabetes and a new application opportunity for SERS-based molecular detection techniques.

Determination of Hydrogen Peroxide Concentration in Biological Samples: a Biosensor-Based Approach

Determination of Hydrogen Peroxide Concentration in Biological Samples: a Biosensor-Based Approach

Profound Hyperthermia Associated With Fentanyl and Cocaine Use With Suspected Synephrine Adulteration

BackgroundAlthough hyperthermia is described after cocaine intoxication, the two hyperthermic cases discussed were unusual in severity and duration for cocaine alone. Synephrine was found in biological samples of these patients in high concentrations and was suspected to be an adulterant in illicitly obtained drugs. Case ReportTwo patients presented to a tertiary care university hospital within 2 days of each other after recreational drug use with delayed and protracted hyperthermia. Synephrine was later found in high concentrations in biological samples as an unexpected drug adulterant. The first patient's presentation came with delayed recognition of hyperthermia and implementation of aggressive cooling measures; he entered multisystem organ failure with prolonged intensive care unit stay and significant morbidity. The second patient's hyperthermia was recognized promptly, and she received early, aggressive cooling, including deep sedation and ice water submersion. She left against medical advice from the hospital at her baseline 3 days after presentation. Why Should an Emergency Physician Be Aware of This?Synephrine is a suspected adulterant that may be associated with profound hyperthermia. Early recognition of drug overdose and working knowledge of common adulterants can facilitate early targeted management, such as aggressive cooling measures, which may prevent morbidity and mortality.

Paraquat and Diquat: Recent Updates on Their Pretreatment and Analysis Methods since 2010 in Biological Samples.

Paraquat (PQ) and diquat (DQ) are quaternary ammonium herbicides which have been used worldwide for controlling the growth of weeds on land and in water. However, PQ and DQ are well known to be toxic. PQ is especially toxic to humans. Moreover, there is no specific antidote for PQ poisoning. The main treatment for PQ poisoning is hemoperfusion to reduce the PQ concentration in blood. Therefore, it is essential to be able to detect PQ and DQ concentrations in biological samples. This critical review summarizes the articles published from 2010 to 2022 and can help researchers to understand the development of the sample treatment and analytical methods for the determination of PQ and DQ in various types of biological samples. The sample preparation includes liquid-liquid extraction, solid-phase extraction based on different novel materials, microextration methods, and other methods. Analytical methods for quantifying PQ and DQ, such as different chromatography and spectroscopy methods, electrochemical methods, and immunological methods, are illustrated and compared. We focus on the latest advances in PQ and DQ treatment and the application of new technologies for these analyses. In our opinion, tandem mass spectrometry is a good choice for the determination of PQ and DQ, due to its high sensitivity, high selectivity, and high accuracy. As far as we are concerned, the best LOD of 4 pg/mL for PQ in serum can be obtained.

Green synthesis of silicon dioxide nanoparticles and L arginine@silicon dioxide nano- composites using cellulose of Zizyphus Spina-Christi along with biological evaluation

ABSTRACT. The recent research focused on the green synthesis of silicon dioxide nanoparticles, SiO2@Cellulose of Zizyphus Spina-Christi nanocomposites, and L-Arginine@SiO2@Cellulose of Zizyphus Spina-Christi nanocomposites using cellulose of Zizyphus Spina-Christi as a new green polymeric surfactant. The structures of nanoparticles and nanocomposites were characterized by different spectroscopy and microscopy techniques. Nanoparticles and nanocomposites were utilized to determine the concentration of chromium, cadmium, and lead in COVID-19 patients using double-vortex-ultrasonic assisted surfactant enhanced dispersive liquid-liquid microextraction. Mean recoveries of chromium, cadmium, and lead were obtained in the range of 86-98% with relative standard deviations below 4%. The advantages of the proposed method are green and novel polymer surfactant with low detection limit. Finally, antibacterial activities were investigated. The maximum inhibition zone of L-Arginine@SiO2@Cellulose of Zizyphus Spina-Christi nanocomposites was obtained for Staphylococcus Aureus (21.9±0.4 mm). L-Arginine@SiO2@Cellulose of Zizyphus Spina-Christi nanocomposites have low cytotoxicity against MCF-7 cancer cells. These results indicated the potential ability of L-Arginine@SiO2@Cellulose of Zizyphus Spina-Christi nanocomposites in the determination of metal concentrations in biological samples along with good antibacterial properties and cytotoxic properties.&#x0D; &#x0D; KEY WORDS: Green synthesis, Cellulose of Zizyphus Spina-Christi, Silicon dioxide nanoparticles, COVID-19, Biological activity&#x0D; &#x0D; Bull. Chem. Soc. Ethiop. 2023, 37(2), 265-276. &#x0D; DOI: https://dx.doi.org/10.4314/bcse.v37i2.2

A One‐step Fluorescence Sensor Based on Molybdenum Disulfide Nanosheets for the Detection of Potassium Ions

AbstractDetermination of potassium ion concentration in biological samples is of great significance due to its vital role in the maintenance of physiological activities. Single or few‐layered transition metal dichalcogenides (TMD, e. g., MoS2, WS2, TiS2) have recently found wide applications in optoelectronics and biomedical engineering. Herein, for the first time, MoS2 nanosheets were integrated with G‐quadraplex DNA secondary structures to construct a fluorescence sensor for detecting potassium ions. The biosensor showed merits such as ease of preparation, ease of use, low‐cost, broad linear working range, as well as sufficient sensitivity, specificity and practical applicability, demonstrating its promise as an effective potassium ion sensor for practical applications. To the best of our knowledge, this is the first report on the combination of TMD nanomaterials and DNA quadraplex for the development of nanodevices. The proposed TMD nanosheets‐G‐quadraplex sensing formulation could enable the devise of other nanomachines and nanosensors considering the versatility of TMD nanomaterials and G‐quadraplex‐containing aptamers.

LC-MS/MS Analysis of AEA and 2-AG.

LC-MS/MS is a powerful analytical technique that provides unequivocal identification and reliable quantification of the analytes, using Selected Reaction Monitoring or Multi Reaction Monitoring acquisition mode.Anandamide (N-arachidonoylethanolamine, AEA) and 2-Arachidonoylglycerol (2-AG) are the most abundant endocannabinoids (eCBs), which play a major role in a wide variety of physiological and pathological processes. Analysis of those compounds by means of LC-MS/MS allows the detection of very low concentrations in biological samples. Here, we describe how to determine AEA and 2-AG levels in tiny samples of tissues and plasma through LC-MS/MS, by using very quick and easy-to-perform extraction procedures, with reduced solvent consumption.