Stir bar sorptive extraction and liquid chromatography with UV detection for determination of antidepressants in plasma samples

A novel nanocomposite based on covalent organic polymer and nanocellulose for thin-film microextraction of imipramine from biological samples

A novel covalent organic polymer was prepared using 1,5-diaminonaphthalene as a linker and cyanuric chloride as a node. A thin-film nanocomposite of 1,5-diaminonaphthalene covalent organic polymer and cellulose nanocrystalline was then fabricated via filtering and casting method. The effect of incorporation of various amounts of 1,5-diaminonaphthalene covalent organic polymer and cellulose nanocrystalline was studied to obtain an efficient nanocomposite thin-film with a large number of polar functional groups and high mechanical stability. Field emission scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectrometry, and thermogravimetric analysis techniques were applied for the characterization of physicochemical properties of the prepared materials. Imipramine was determined in the biological samples using thin-film microextraction followed by gas chromatography flame ionization detection. Parameters affecting the extraction efficiency of imipramine were investigated. Under the optimized conditions, the limit of detection was 0.5 ng/mL. Film-to-film reproducibility for three different films fabricated under the same conditions (at three concentration levels) varied between 8.9 and 9.7%. The linear dynamic range covered more than three orders of magnitude (2-5000 ng/mL) with a determination coefficient of 0.9985. The method was successfully applied for preconcentration and determination of imipramine in biological samples with spiking recoveries between 78 and 93%.

Sensitive determination of Fluoxetine and Citalopram antidepressants in urine and wastewater samples by liquid chromatography coupled with photodiode array detector

A new analyte separation and preconcentration method for the trace determination of antidepressant drugs, Fluoxetine (FLU) and Citalopram (CIT) in urine and wastewaters, was developed based on HPLC-DAD analysis after magnetic solid phase extraction (MSPE). In the proposed method, FLU and CIT were retained on the newly synthetized magnetic sorbent (Fe₃O₄@PPy-GO) in the presence of buffer (pH 10.0) and then were desorbed into a lower volume of acetonitrile prior to the chromatographic determinations. Before HPLC analysis, all samples were filtered through a 0.45 µm PTFE filter. Experimental parameters such as interaction time, desorption solvent and volume, and pH were studied and optimized in order to establish the detection limit, linearity, enrichment factor and other analytical figures of merit under optimum operation conditions. In the developed method, FLU and CIT were analyzed by diode array detector at the corresponding maximum wavelengths of 227 and 238 nm, respectively, by using an isocratic elution of 60% pH 3.0 buffer, 30% acetonitrile, and 10% methanol. By using the optimum conditions, limit of detections for FLU and CIT were 1.58 and 1.43 ng mL^-1, respectively, while the limit of quantifications was 4.82 and 4.71 ng mL^-1, respectively. Relative standard deviations (RSD%) for triplicate analyses of model solutions containing 100 ng mL^-1 target molecules were found to be less than 5.0 %. Finally, the method was successfully applied to urine (both simulated and real healthy human) and wastewater samples, and quantitative results were obtained in recovery experiments.

Magnetic solid-phase extraction coupled with UHPLC-MS/MS for four antidepressants and one metabolite in clinical plasma and urine samples

Aim: Routine therapeutic drug monitoring is highly recommended since common antidepressant combinations increase the risk of drug-drug interactions or overlapping toxicity. Materials & methods: A magnetic solid-phase extraction by using C₁₈-functionalized magnetic silica nanoparticles (C₁₈-Fe₃O₄@SiO₂ NPs) as sorbent was proposed for rapid extraction of venlafaxine, paroxetine, fluoxetine, norfluoxetine and sertraline from clinical plasma and urine samples followed by ultra-HPLC-MS/MS assay. Results: The synthesized C₁₈-Fe₃O₄@SiO₂ NPs showed high magnetization and efficient extraction for the analytes. After cleanup by magnetic solid-phase extraction, no matrix effects were found in plasma and urine matrices. The analytes showed LODs among 0.15-0.75 ng ml^-1, appropriate linearity (R ≥ 0.9990) from 2.5 to 1000 ng ml^-1, acceptable accuracies 89.1-110.9% with precisions ≤11.0%. The protocol was successfully applied for the analysis of patients' plasma and urine samples. Conclusion: It shows high potential in routine therapeutic drug monitoring of clinical biological samples.

New-generation bar adsorptive microextraction (BAμE) devices for a better eco-user-friendly analytical approach-Application for the determination of antidepressant pharmaceuticals in biological fluids

The present contribution aims to design new-generation bar adsorptive microextraction (BAμE) devices that promote an innovative and much better user-friendly analytical approach. The novel BAμE devices were lab-made prepared having smaller dimensions by using flexible nylon-based supports (7.5 × 1.0 mm) coated with convenient sorbents (≈ 0.5 mg). This novel advance allows effective microextraction and back-extraction ('only single liquid desorption step') stages as well as interfacing enhancement with the instrumental systems dedicated for routine analysis. To evaluate the achievements of these improvements, four antidepressant agents (bupropion, citalopram, amitriptyline and trazodone) were used as model compounds in aqueous media combined with liquid chromatography (LC) systems. By using an N-vinylpyrrolidone based-polymer phase good selectivity and efficiency were obtained. Assays performed on 25 mL spiked aqueous samples, yielded average recoveries in between 67.8 ± 12.4% (bupropion) and 88.3 ± 12.1% (citalopram), under optimized experimental conditions. The analytical performance also showed convenient precision (RSD < 12%) and detection limits (50 ng L^-1), as well as linear dynamic ranges (160-2000 ng L^-1) with suitable determination coefficients (r² > 0.9820). The application of the proposed analytical approach on biological fluids showed negligible matrix effects by using the standard addition methodology. From the data obtained, the new-generation BAμE devices presented herein provide an innovative and robust analytical cycle, are simple to prepare, cost-effective, user-friendly and compatible with the current LC autosampler systems. Furthermore, the novel devices were designed to be disposable and used together with negligible amounts of organic solvents (100 μL) during back-extraction, in compliance with the green analytical chemistry principles. In short, the new-generation BAμE devices showed to be an eco-user-friendly approach for trace analysis of priority compounds in biological fluids and a versatile alternative over other well-stablished sorption-based microextraction techniques.

QbD-Driven Development and Validation of a Bioanalytical LC-MS Method for Quantification of Fluoxetine in Human Plasma

The current studies describe the Quality by Design (QbD)-based development and validation of a LC-MS-MS method for quantification of fluoxetine in human plasma using fluoxetine-D5 as an internal standard (IS). Solid-phase extraction was employed for sample preparation, and linearity was observed for drug concentrations ranging between 2 and 30 ng/mL. Systematic optimization of the method was carried out by employing Box-Behnken design with mobile phase flow rate (X1), pH (X2) and mobile phase composition (X3) as the method variables, followed by evaluating retention time (Rt) (Y1) and peak area (Y2) as the responses. The optimization studies revealed reduction in the variability associated with the method variables for improving the method robustness. Validation studies of the developed method revealed good linearity, accuracy, precision, selectivity and sensitivity of fluoxetine in human plasma. Stability studies performed in human plasma through freeze-thaw, bench-top, short-term and long-term cycles, and autosampler stability revealed lack of any change in the percent recovery of the drug. In a nutshell, the developed method demonstrated satisfactory results for analysis of fluoxetine in human plasma with plausible utility in pharmacokinetic and bioequivalence studies.

Determination of selective serotonin reuptake inhibitors in biological samples via magnetic stirring-assisted dispersive liquid–liquid microextraction followed by high performance liquid chromatography

This work reports an efficient, quick and low-cost procedure for the determination of serotonin reuptake inhibitors (SSRIs) in low concentration levels in biological fluids.

A Simple, Rapid and Reliable Method to Determine Imipramine and Desipramine in Mouse Serum Using Ultra-High-Performance Liquid Chromatography-Quadrupole-Time-of-Flight Mass Spectrometry

A rapid and sensitive ultra-high-performance liquid chromatography-quadrupole-time-of-flight mass spectrometric (UHPLC-Q-TOF-MS) method was developed for quantification of imipramine, one of the most widely used tricyclic antidepressants, and desipramine, an active metabolite of imipramine, in mouse serum. The developed method included a simple protein precipitation with acetonitrile in 50 μL of serum and analyte separation on an Acquity UPLC BEH C18 column using a gradient elution of acetonitrile with 0.1% formic acid and 20 mM ammonium formate. As a result, the entire analysis time was <20 min including the sample preparation and the LC-MS analysis. The limit of quantification was 5.0 ng mL(-1) for both imipramine and desipramine, and calibration curves were linear over the concentration range of 5.0-1,000.0 and 5.0-250.0 ng mL(-1) for imipramine and desipramine, respectively. Intraday precisions at three levels were 2.2-3.6 and 1.7-4.2% for imipramine and desipramine, respectively, whereas interday precisions were 2.6-5.0 and 2.0-8.4% for imipramine and desipramine, respectively. Accuracy ranged between 93.6 and 106.6% for imipramine and 94.1 and 106.4% for desipramine. Absolute recovery was 96.0-97.6% for imipramine and 87.0-99.5% for desipramine. Finally, the described method was applied to mice administered with imipramine, demonstrating the suitability for quantification of imipramine and desipramine for therapeutic drug monitoring or bioequivalence studies.

Stir bar sorptive extraction applied to the analysis of biological fluids

Stir bar sorptive extraction (SBSE) is a sample preparation technique, which is used for the extraction as well as the preconcentration of organic substances from various aqueous matrices, prior to the determination of the analytes with a separation technique, such as LC or GC, coupled to different detectors. Since 1999, when SBSE was first developed by Sandra and co-workers, SBSE has been used in the analysis of samples of environmental, food, pharmaceutical and biomedical origin. In this article, we focus on the application of SBSE in biological fluids.

Hollow fiber based liquid–liquid–liquid microextraction combined with sweeping micellar electrokinetic chromatography for the sensitive determination of second-generation antidepressants in human fluids

HF-LPME is combined with sweeping MEKC for the sensitive determination of second-generation antidepressants in human fluids.

Magnetic solid phase extraction coupled with desorption corona beam ionization-mass spectrometry for rapid analysis of antidepressants in human body fluids

A rapid analysis method by coupling magnetic solid phase extraction (MSPE) with desorption corona beam ionization (DCBI) is presented.

Biological sample preparation: attempts on productivity increasing in bioanalysis

Sample preparation is an important step of any biomedical analysis. Development and validation of fast, reproducible and reliable sample preparation methods would be very helpful in increasing productivity. Except for a few direct injection methods, almost all biological samples should at least be diluted before any analysis. Sometimes dilution is not possible because of the low concentration of the target analyte in the sample, and alternative pretreatments, such as filtration, precipitation and sample clean up using different extraction methods, are needed. This review focuses on the recent achievements in the pretreatment of biological samples and investigates them in six categories (i.e., dilution, filtration/dialysis, precipitation, extraction [solid-phase extraction, liquid–liquid extraction], novel techniques [turbulent flow chromatography, immunoaffinity method, electromembrane extraction] and combined methods). Each category will be discussed according to its productivity rate and suitability for routine analysis, and the discussed methods will be compared according to the mentioned indices.

A critical review of microextraction by packed sorbent as a sample preparation approach in drug bioanalysis

Sample preparation is widely accepted as the most labor-intensive and error-prone part of the bioanalytical process. The recent advances in this field have been focused on the miniaturization and integration of sample preparation online with analytical instrumentation, in order to reduce laboratory workload and increase analytical performance. From this perspective, microextraction by packed sorbent (MEPS) has emerged in the last few years as a powerful sample preparation approach suitable to be easily automated with liquid and gas chromatographic systems applied in a variety of bioanalytical areas (pharmaceutical, clinical, toxicological, environmental and food research). This paper aims to provide an overview and a critical discussion of recent bioanalytical methods reported in literature based on MEPS, with special emphasis on those developed for the quantification of therapeutic drugs and/or metabolites in biological samples. The advantages and some limitations of MEPS, as well as its comparison with other extraction techniques, are also addressed herein.

Pre-concentration and determination of amitriptyline residues in waste water by ionic liquid based immersed droplet microextraction and HPLC

This paper describes a new approach for the determination of amitriptyline in wastewater by ionic liquid based immersed droplet microextraction (IL-IDME) prior to high-performance liquid chromatography with ultraviolet detection. 1-Hexyl-3-methylimidazolium hexafluorophosphate ([C₆MIM][PF₆]) was used as an ionic liquid. Various factors that affect extraction, such as volume of ionic liquid, stirring rate, extraction time, pH of the aqueous solution and salting effect, were optimized. The optimal conditions were as follows: microextraction time, 10 min; stirring rate, 720 rpm; pH, 11; ionic drop volume, 100 μL; and no sodium chloride addition. In quantitative experiments the method showed linearity in a range from 0.01 to 10 μg/mL, a limit of detection of 0.004 μg/mL and an excellent pre-concentration factor (PF) of 1100. Finally, the method was successfully applied to the determination of amitriptyline in the hospital wastewater samples.

Microextraction techniques in therapeutic drug monitoring

Therapeutic drug monitoring (TDM), as part of clinical process of medical treatments, is commonly used to maintain 'therapeutic' drug concentrations. TDM is useful to identify the causes of unwanted or unexpected responses, to prevent unnecessary diagnostic testing, to improve clinical outcomes, and even to save lives. The determination of drug concentration in blood samples requires an excellent sample preparation procedure. Recent trends in sample preparation include miniaturization, automation, high-throughput performance, on-line coupling with analytical instruments and low-cost operation through extremely low or no solvent consumption. Microextraction techniques, such as liquid- and solid-phase microextraction, have these advantages over the traditional techniques. This paper reviews the recent developments in microextraction techniques used for drug monitoring in serum, plasma or blood samples.

Role of microextraction sampling procedures in forensic toxicology

The last two decades have provided analysts with more sensitive technology, enabling scientists from all analytical fields to see what they were not able to see just a few years ago. This increased sensitivity has allowed drug detection at very low concentrations and testing in unconventional samples (e.g., hair, oral fluid and sweat), where despite having low analyte concentrations has also led to a reduction in sample size. Along with this reduction, and as a result of the use of excessive amounts of potentially toxic organic solvents (with the subsequent environmental pollution and costs associated with their proper disposal), there has been a growing tendency to use miniaturized sampling techniques. Those sampling procedures allow reducing organic solvent consumption to a minimum and at the same time provide a rapid, simple and cost-effective approach. In addition, it is possible to get at least some degree of automation when using these techniques, which will enhance sample throughput. Those miniaturized sample preparation techniques may be roughly categorized in solid-phase and liquid-phase microextraction, depending on the nature of the analyte. This paper reviews recently published literature on the use of microextraction sampling procedures, with a special focus on the field of forensic toxicology.

Microassay of drugs and modern measurement techniques

Details of the development of conventional analytical methods for the determination of drugs in pediatric plasma/serum samples via microassays are presented. Examples of the development of small-volume sampling and the use of the newer detection systems such as LC/MS/MS for enhanced detection are presented. Dried blood spot sampling has conventionally been used for the study of inborn errors of metabolism using Guthrie cards. Limited applications in the area of drug-level determination, for example, in therapeutic drug monitoring had been reported but the methodology had not been widely used up until relatively recently. In the last few years, there has been a resurgence of interest in this methodology for drug-level determinations, and examples of drug analysis in pediatric and neonatal patients where the small-volume samples are particularly useful are presented. The application of the methodology in pharmacokinetic/pharmacodynamic studies is discussed. The utilization of solid-phase microextraction and stir bar sorptive extraction in drug analysis is presented. Clinical applications of these methodologies are reported including the development of in vivo solid-phase microextraction.