Simple and green synthesis of carbon dots (CDs) from valerian root and application of modified mesoporous boehmite (AlOOH) with CDs as a fluorescence probe for determination of imipramine.

A novel, sensitive, rapid, and simple fluorescent probe has been developed based on green-synthesized carbon dots (CDs). In this work, CDs have been synthesized from valerian root by hydrothermal method. Transmission electron microscopy (TEM) and dynamic light scattering (DLS) results confirm the formation of CDs with sizes of less than 10 nm. Fluorescence quenching of CDs was due to the aggregation of the negative charges of CDs with the positive charge of imipramine (IMI) and was then used as the signal for determination of IMI. In addition, the cytotoxicity of CDs was determined using the MTT assay. The probe responses under optimum conditions were linear in the range of 1.0-200.0 ng mL-1 with a limit of detection of 0.6 ng mL-1. Afterwards, mesoporous boehmite (MB) was modified with synthesized CDs (CDs/MB). TEM images confirmed MB modification with CDs. In this case, the variations in the fluorescence signal for different concentrations of IMI increased leading to the higher sensitivity for IMI detection. The limit of detection and linear range for determination of IMI with CDs/MB were obtained as 0.2 and 0.5-200.0 ng mL-1, respectively. To evaluate the fluorescent probe, IMI was measured in real samples. Graphical abstract.

Extraction and determination of tricyclic antidepressants in real samples using air-dispersed liquid-liquid microextraction prior to gas chromatography and flame ionization detection.

In the present research, a novel microextraction method was used based on dispersive liquid-liquid microextraction using low-density solvent for the determination of trace amounts of amitriptyline and doxepin as model compounds in human plasma and spring water samples before gas chromatography and flame ionization detection. The parameters influencing the extraction efficiencies including type of the extracting solvent, volume of the aqueous sample solution (donor phase), volume of the extraction solvent (acceptor phase), the number of air-injection, and the effects of pH and ionic strength were optimized. Under the optimized conditions, the obtained enrichment factors were >80. By plotting peak areas of the sample solutions versus various concentrations of the analytes, calibration curves were obtained which show the linear ranges of 10-3000 ng/mL with correlation coefficients of >0.996. The precision of the method was calculated <4.2 and the limit of detection was 1 ng/mL for two analytes. The proposed microextraction method was used for the extraction of the analytes in environmental water and plasma samples and the calculated relative recoveries were all >91%.

Determination of tricyclic antidepressants in biota tissue and environmental waters by liquid chromatography-tandem mass spectrometry.

This work describes the optimization, validation, and application in real samples of accurate and precise analytical methods to determine tricyclic antidepressants (TCAs), including amitriptyline, nortriptyline, imipramine, and clomipramine in different environmental matrices, such as water (estuary, seawater, and wastewater treatment plant effluent) and biota (fish muscle, fish liver, and mussels), which would lead to supplement the scarce information on the presence of TCAs in aquatic organisms. The analysis step performed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) was fully optimized to improve the sensitivity of the separation and detection steps. The extraction of solid samples was accomplished using focused ultrasonic solid-liquid extraction (FUSLE), which required a low amount of sample (0.5 g), solvent (7 mL acetonitrile/H2O, 95:5 v/v) and short extraction time (30 s). In the optimisation of the clean-up step, mixed mode solid-phase extraction (SPE) using a strong cation exchanger rendered clean extracts and the best results in terms of extraction efficiency and matrix effect. The same SPE mode was also used for the extraction and pre-concentration of TCAs from environmental water matrices. The methods afforded satisfactory apparent recovery values (86-122%) and repeatability (RSD < 5%), regardless of the matrix. Finally, the developed methods were applied to the analysis of real samples from the Biscay Coast, where TCAs were detected in both water and biota samples up to 25.9 ng/L and 1.8 ng/g, respectively. Up to our knowledge, this is the first work using FUSLE for the determination of TCAs and one of the few analyzing TCAs in biota samples.

[The determination of amitriptyline and its metabolite, nortriptyline, in the biological objects of the corpse by the high-performance liquid chromatography technique].

Tricyclic antidepressants are among the preparations that most frequently cause intoxication in adults and children; moreover, poisoning with these substances not infrequently has a fatal outcome. Medications belonging to this group, such as amitriptyline, are extensively used to manage manifestations of depression, anxiety, migraine, neuropathic pain, and hyperactivity syndrome. Amitriptyline overdosage causes non-specific symptoms of intoxication, and its clinical picture does not allow to identify the nature of a psychotropic xenobiotic. Of primary importance in connection with this is to establish the cause of intoxication or death by the clinical toxicological and forensic medical methods based on the results of the fast identification and quantitation of amitriptyline in biological materials including blood, urine, hepatic tissues, etc. The authors describe the method for the determination of amitriptyline and its principal physiological metabolite nortriptyline in biological objects with the help of high performance liquid chromatography (HPLC).

Application of a new fiber coating based on electrochemically reduced graphene oxide for the cold-fiber headspace solid-phase microextraction of tricyclic antidepressants.

A new fiber based on the electrochemical reduction of graphene oxide was prepared on a copper wire for solid-phase microextraction (SPME) applications. The prepared fiber was used for the SPME and gas chromatographic analysis of tricyclic antidepressants (TCADs), including amitriptyline, trimipramine, and clomipramine. The feasibility of direct-immersion and headspace modes of SPME for the determination of TCADs was studied. The effects of four parameters including pH, salt content, extraction temperature with and without cooling the fiber, and extraction time were investigated. The comparison showed that headspace cold fiber SPME results in the best outcome for the extraction of TCADs. Under the optimized conditions of this mode, the calibration curves were linear between 2.0 and 500 ng/mL and the detection limits were between 0.30 and 0.53 ng/mL. The intraday and interday RSDs obtained at 20 ng/mL (n = 5), using a single fiber, were 5.5-9.0 and 7.5-9.8, respectively. The fiber to fiber repeatability (n = 4), expressed as the RSD, was between 12.8 and 13.2% at a 20 ng/mL concentration level. The method was successfully applied to the analysis of TCADs in plasma samples showing recoveries from 73 to 96%.

[The identification and quantitative measurement of mirtazapine isolated from the biological material by high performance liquid chromatography].

The present study was designed to estimate the effectiveness of isolation of mirtazapine from the liver, blood, and urine. The conditions were developed for the identification and quantitative measurement of the isolated mirtazapine with the use of high performance liquid chromatography and detection from the UV-spectrum and mass-spectrometry. The retention time of mirtazapine isolated from the liver was 2.88 +/- 0.08 min. The straight-line equation within the range of mirtazapine concentrations from 1 to 20 mc/ml was characterized by the dependence: Y = 3.25 x 10(4)X - 6.27 x 10(3) (r = 0.9997). The study showed that it is possible to isolate 46.44 +/- 1.89% of mirtazapine present in the liver and 50.4 +/- 1.05% from blood using extraction by acetonitrile acidified with an 1 M hydrochloric acid solution. Chloroform extraction from urine at pH 7.0-8.0 releases 90.22 +/- 1.88% of mirtazapine.

Adsorptive stripping voltammetric determination of imipramine, trimipramine and desipramine employing titanium dioxide nanoparticles and an Amberlite XAD-2 modified glassy carbon paste electrode.

An Amberlite XAD-2 (XAD2) and titanium dioxide nanoparticles (TNPs) modified glassy carbon paste electrode (XAD2-TNP-GCPE) was developed for the determination of imipramine (IMI), trimipramine (TRI) and desipramine (DES). The electrochemical behavior of these molecules was investigated employing cyclic voltammetry (CV), chronocoulometry (CC), electrochemical impedance spectroscopy (EIS) and adsorptive stripping differential pulse voltammetry (AdSDPV). After optimization of analytical conditions using a XAD2-TNP-GCPE electrode at pH 6.0 phosphate buffer (0.1 M), the peak currents were found to vary linearly with its concentration in the range of 1.30 × 10(-9) to 6.23 × 10(-6) M for IMI, 1.16 × 10(-9) to 6.87 × 10(-6) M for TRI and 1.43 × 10(-9) to 5.68 × 10(-6) M for DES. The detection limits (S/N = 3) of 3.93 × 10(-10), 3.51 × 10(-10) and 4.35 × 10(-10) M were obtained for IMI, TRI and DES respectively using AdSDPV. The prepared modified electrode showed several advantages such as a simple preparation method, high sensitivity, very low detection limits and excellent reproducibility. The proposed method was employed for the determination of IMI, TRI and DES in pharmaceutical formulations, blood serum and urine samples.

In-situ growth of covalent organic framework on stainless steel needles as solid-phase microextraction probe coupled with electrospray ionization mass spectrometry for rapid and sensitive determination of tricyclic antidepressants in biosamples.

Tricyclic antidepressants (TCAs) including amitriptyline (AT), doxepin (DOX) and nortriptyline (NT) are the first-line drugs for the clinical treatment of depression; however, monitoring TCA concentrations in biological fluids and tissues is necessary to improve therapeutic effect and determine the cause of death in patients. It is of great significance to develop a rapid and sensitive method for real-time monitoring of TCAs in various biosamples. In this work, we fabricated a novel covalent organic framework (COF) based solid-phase microextraction (SPME) probe by an in-situ step-by-step strategy, which was obtained by sequentially modifying 1,3,5-tri (4-aminophenyl) benzene (TPB) and 2, 5-divinylbenzaldehyde (DVA) on the surface of polydopamine layer. The TPB-DVA-COF-SPME probe possessed high specific surface area (1244 m2·g - 1), regular pores (3.23 nm), good hydrophobicity and stability, resulting in efficient enrichment for TCAs. Furthermore, the combination of TPB-DVA-COF-SPME probe and ambient electrospray ionization mass spectrometry system (ESI/MS) was firstly proposed for rapid and sensitive determination of TCAs in biosamples. As a result, the developed method exhibited low limits of detection (LODs) (0.1-0.5 µg∙L - 1), high enrichment factors (39-218), and low relative standard deviations (RSDs) for one probe (1.2-3.8%) and probe-to-probe (2.0-3.7%). Benefiting from these outstanding performance, TPB-DVA-COF-SPME probe was further successfully applied to biosamples (i.e., serum, liver, kidney, and brain) with excellent reusability, indicating the promising applicability of the TPB-DVA-COF-SPME-ESI/MS as a powerful tool for drug monitoring.

On-Chip Electromembrane Surrounded Solid Phase Microextraction for Determination of Tricyclic Antidepressants from Biological Fluids Using Poly(3,4-ethylenedioxythiophene)-Graphene Oxide Nanocomposite as a Fiber Coating.

In the present study, on-chip electromembrane surrounded solid phase microextraction (EM-SPME) was employed in the determination of tricyclic antidepressants (TCAs), including amitriptyline, nortriptyline, imipramine, desipramine, maprotiline, and sertraline, from various biological fluids. In this regard, poly(3,4-ethylenedioxythiophene)-graphene oxide (PEDOT-GO) was electrodeposited on an SPME fiber as a conductive coating, then the fiber played the acceptor-electrode role during the extraction. Thus, the immigration of the analytes under the influence of an electric field and their absorption onto the fiber coating were accomplished simultaneously. Under the optimized conditions, the limits of detection for the target analytes were acquired in the range of 0.005-0.025 µg L-1 using gas chromatography-mass spectrometry. The linearity of the method was 0.010-500 µg L-1 for the imipramine and sertraline, 0.025-500 µg L-1 for the amitriptyline, nortriptyline, and desipramine, and 1.000-250 µg L-1 for the maprotiline (R2 ≥ 0.9984). Moreover, this method provided suitable precision and fiber-to-fiber reproducibility, with RSDs ≤ 8.4%. The applicability of the proposed setup was eventually investigated for extraction of the drugs from human bone marrow aspirate, urine, plasma, and well water samples, in which satisfactory relative recoveries, from 93-105%, were obtained.

Reversed-phase liquid chromatography without organic solvent for determination of tricyclic antidepressants.

The chromatographic behavior of seven tricyclic antidepressants (amitryptiline, clomipramine, doxepin, imipramine, maprotiline, nortryptiline, and trimipramine) was examined with micellar mobile phases containing the nonionic surfactant Brij-35. Acetonitrile-water mixtures were also used for comparison purposes. Tricyclic antidepressants are moderately polar basic drugs, which are positively charged in the usual working pH. This gives rise to a strong association with the alkyl chains and residual ionized silanols in silica-based stationary phases, which is translated in a high consumption of organic solvent to get appropriate retention times. Brij-35 modifies the surface of the stationary phases creating a neutral bilayer that masks silanols and reduces the polarity. Consequently, the retention times are decreased. A simple chromatographic procedure for the control of tricyclic antidepressants in pharmaceutical formulations was developed, using 0.02 M Brij-35 at pH 3 and UV detection. Satisfactory recoveries were achieved, with intra- and inter-day relative standard deviations usually below 1 and 2%, respectively. The preparation of the samples was simple and only required solubilization and filtration steps previous to injection. The proposed procedure has the advantage of not using an organic solvent in the mobile phase, and the biodegradable character of Brij-35. This makes an example of "green" liquid chromatographic analysis.

Investigation of the performance of cross-linked poly(acrylic acid) and poly(methacrylic acid) as efficient adsorbents in SPE columns for simultaneous preconcentration of tricyclic antidepressants in water samples.

A solid phase extraction-based (SPE) procedure for simultaneous preconcentration of five tricyclic antidepressants (TCAs), amitriptyline hydrochloride (AMT), nortriptyline hydrochloride (NOR), doxepin hydrochloride (DOX), imipramine hydrochloride (IMI), and clomipramine hydrochloride (CLO) from water samples with determination by HPLC-DAD is proposed. Polymers were characterized by FT-IR, SEM, and thermogravimetric analysis. SPE-based methods were carried out by the preconcentration of 320.0 mL of TCAs at pH 7.0 (buffered with 0.01 mol L-1 phosphate buffer) through 70.0 mg of adsorbent packed into a SPE cartridge, followed by elution with 1.0 mL of ACN : MeOH : acetic acid solution (45 : 45 : 10% v/v). Higher preconcentration factors were obtained ranging from 117.9 to 372.2 and 207.1 to 396.1 by using poly(MAA-co-EGDMA) and poly(AA-co-EGDMA), respectively, yielding lower limits of detection (0.03 to 0.12 µg L-1) and (0.03 to 0.15 µg L-1). These outcomes show satisfactory detectability of SPE-based methods, with slightly better performance using poly(MAA-co-EGDMA). On the other hand, poly(AA-co-EGDMA) was able to preconcentrate TCAs in the presence of humic acid (7.0 mg L-1) without interference. The precision of methods assessed as RSD (%) was very similar, ranging from 1.7% to 16.3% for poly(MAA-co-EGDMA) and 1.7% to 13.4% for poly(AA-co-EGDMA). SPE cartridges packed with the polymers showed high reusability (52 cycles of preconcentration and elution) without losing adsorption efficiency. The methods were applied to determine TCAs in tap, lake, and stream water samples and the accuracy was attested by addition and recovery tests (86.7-116.0%), with determined nortriptyline ranging from 0.48 to 0.52 µg L-1 in lake water samples.

Evaluation of the potential of surface enhancement Raman spectroscopy for detection of tricyclic psychotropic drugs. Case studies on imipramine and its metabolite.

The potential use of surface Raman enhanced spectroscopy (SERS) for confirmatory identification and the semi-quantitative analysis of selected tricyclic antidepressants (TCAs) is examined utilizing a conventional silver colloid. Raman and SERS spectra of aqueous solutions of imipramine (Imi) and its metabolite, desipramine (Des), were recorded as the function of concentration using NIR excitation. A good linear correlation is observed for the dependence of the SERS signal at 684 cm(-1) (R(2) = 0.9997) on Imi concentration over the range of 0.75-7.5 µM. The limit of detection of imipramine in the silver colloidal solution is 0.98 µM. SERS spectra of Imi and Des were also recorded for blood plasma samples without prior purification as well as after the use of standard solid phase extraction. All spectra show the characteristic spectral profile of the molecules and moreover, stronger signal enhancement is observed for Imi in the "raw" samples as opposed to Imi extracted from a biological matrix.

Microwave-assisted hydrolysis and extraction of tricyclic antidepressants from human hair.

The objective of this research was to develop, optimize, and validate a modern, rapid method of preparation of human hair samples, using microwave irradiation, for analysis of eight tricyclic antidepressants (TCADs): nordoxepin, nortriptyline, imipramine, amitriptyline, doxepin, desipramine, clomipramine, and norclomipramine. It was based on simultaneous alkaline hair microwave-assisted hydrolysis and microwave-assisted extraction (MAH-MAE). Extracts were analyzed by high-performance liquid chromatography with diode-array detection (HPLC-DAD). A mixture of n-hexane and isoamyl alcohol (99:1, v/v) was used as extraction solvent and the process was performed at 60°C. Application of 1.0 mol L(-1) NaOH and microwave irradiation for 40 min were found to be optimum for hair samples. Limits of detection ranged from 0.3 to 1.2 µg g(-1) and LOQ from 0.9 to 4.0 µg g(-1) for the different drugs. This enabled us to quantify them in hair samples within average therapeutic concentration ranges.

Source characterization of nervous system active pharmaceutical ingredients in healthcare facility wastewaters.

Nervous system active pharmaceutical ingredients (APIs), including anti-depressants and opioids, are important clinically administered pharmaceuticals within healthcare facilities. This study provides source characterization data describing the composition and magnitude of nervous system APIs present in healthcare facility wastewaters. Concentrations and mass loadings of ten nervous system APIs and three nervous system API metabolites are reported for wastewaters from a hospital, nursing, assisted living, and independent living facility within a single municipality. Concentrations of nervous system APIs ranged from non-detectable levels for alprazolam in all four facility wastewaters to a high of 290 ng/L amitriptyline in nursing facility wastewater. The summed mean concentration of all thirteen analytes ranged from 402 ng/L in independent living facility wastewater to 624 ng/L in assisted living facility wastewater. Wastewater flow rates from each facility were combined with concentration data to estimate the daily mass loading of nervous system APIs leaving each facility through wastewater discharge to the municipal sewer system. The total mass loading of all thirteen analytes for the hospital, nursing, assisted living, and independent living facility was 228, 44, 29.5, and 28.1 mg/day, respectively. The total mass loading of nervous system APIs contributed to the municipality's wastewater from all four facilities was 330 mg/day.

Enantioselective analysis of mirtazapine, demethylmirtazapine and 8-hydroxy mirtazapine in human urine after solid-phase microextraction.

A selective and reproducible off-line solid-phase microextraction procedure was developed for the simultaneous enantioselective determination of mirtazapine (MRT), demethylmirtazapine and 8-hydroxymirtazapine in human urine. CE was used for optimization of the extraction procedure whereas LC-MS was used for method validation and application. The influence of important factors in the solid-phase microextraction efficiency is discussed, such as the fiber coatings, extraction time, pH, ionic strength, temperature and desorption time. Before extraction, human urine samples were submitted to enzymatic hydrolysis at 37 degrees C for 16 h. Then, the enzyme was precipitated with trichloroacetic acid and the pH was adjusted to 8 with 1 mol/L pH 11 phosphate buffer solution. In the extraction, the analytes were transferred from the aqueous solution to the polydimethylsiloxane-divinylbenzene fiber coating and then desorbed in methanol. The mean recoveries were 5.4, 1.7 and 1.0% for MRT, demethylmirtazapine and 8-hydroxymirtazapine enantiomers, respectively. The method was linear over the concentration range of 62-1250 ng/mL. The within-day and between-day assay precision and accuracy were lower than 15%. The method was successfully employed in a preliminary cumulative urinary excretion study after administration of racemic MRT to a healthy volunteer.

Simultaneous determination of imipramine hydrochloride and chlordiazepoxide in pharmaceutical preparations by spectrophotometric, RP-HPLC, and HPTLC methods.

A binary mixture of imipramine HCl and chlordiazepoxide was determined by three different methods. The first involved determination of imipramine HCl and chlordiazepoxide using the first derivative spectrophotometric technique at 219 and 231.5 nm over the concentration ranges of 1-20 and 2-24 microg/mL with mean accuracies of 99.47 +/- 0.78 and 101.43 +/- 1.20%, respectively. The second method utilized RP-HPLC with methanol-acetonitrile-0.065 M ammonium acetate buffer (45 + 25 + 30, v/v/v, pH adjusted to 5.6 +/- 0.02 with phosphoric acid) as the mobile phase pumped at a flow rate of 1.0 mL/min. Quantification was achieved using UV detection at 240 nm over concentration ranges of 0.25-4.0 and 0.1-1.6 microg/mL, with mean accuracies of 101.17 +/- 0.56 and 100.67 +/- 0.40% for imipramine HCl and chlordiazepoxide, respectively. The third method was HPTLC with carbon tetrachloride-acetone-triethylamine (pH 8.3; 6 + 3 + 0.3, v/v/v) as the mobile phase. Quantification was achieved with UV detection at 240 nm over concentration ranges of 50-600 and 20-240 ng/spot with mean accuracies of 99.51 +/- 0.59 and 100.59 +/- 0.84% for imipramine HCl and chlordiazepoxide, respectively. The suggested procedures were checked using prepared mixtures, and were successfully applied for the analysis of pharmaceutical preparations. The accuracy and precision of the methods were confirmed when the standard addition technique was applied. The results obtained by applying the proposed methods were statistically analyzed.

Recent Advances in the HPLC Analysis of Tricyclic Antidepressants in Bio-Samples.

Tricyclic Antidepressants (TCAs) are a group of the main category of antidepressant drugs, which are commonly prescribed to treat major depressive disorder. Determination of TCA drugs is very important for clinical and forensic toxicology, especially for therapeutic drug monitoring in various biofluids. High Performance Liquid Chromatography (HPLC) is a well-established technique for this purpose. A lot of progress has been made in this field since the past 10 years. Novel extraction techniques, and novel materials for sample preparation, novel columns and novel applications of analysis of various biofluids for the determination of TCAs in combination with other drugs are some typical examples. Moreover, advances have been performed in terms of Green Analytical Chemistry principles. Herein, we aim to discuss the developed HPLC methods that were reported in the literature for the time span of 2008-2018.

HPLC as a tool in medicinal chemistry for the monitoring of tricyclic antidepressants in biofluids.

HPLC is discussed as an essential tool in medicinal chemistry for the monitoring of tricyclic antidepressants in biofluids, providing clinicians with efficient fast and reliable methods to define individual optimum therapeutic concentrations in treatment of depressions. Additional information on mechanism of action, structure activity relationship and metabolism is provided.

A whole-cell assay for the high throughput screening of calmodulin antagonists.

Cell-based screening systems for pharmaceuticals are desired over molecular biosensing systems because of the information they provide on toxicity and bioavailability. However, the majority of sensing systems developed are molecular biosensing type screening systems and cannot be easily adapted to cell-based screening. In this study, we demonstrate that protein-based molecular sensing systems that employ a fluorescent protein as a signal transducer are amenable to cell-based sensing by expressing the protein molecular sensing system in the cell and employing these cells for screening of desired molecules. To achieve this, we expressed a molecular sensing system based on the fusion protein of calmodulin (CaM) and enhanced green fluorescent protein (EGFP) in bacterial cells, and utilized these cells for the screening of CaM antagonists. In the presence of Ca(2+), CaM undergoes a conformational change exposing a hydrophobic pocket that interacts with CaM-binding proteins, peptides, and drugs. This conformational change induced in CaM leads to a change in the microenvironment of EGFP, resulting in a change in its fluorescence intensity. The observed change in fluorescence intensity of EGFP can be correlated to the concentration of the analyte present in the sample. Dose-response curves for various tricyclic antidepressants were generated using cells containing CaM-EGFP fusion protein. Additionally, we demonstrate the versatility of our system for studying protein-protein interactions by using cells to study the binding of a peptide to CaM. The study showed that the CaM-EGFP fusion protein within the intact cells responds similarly to that of the isolated fusion protein, hence eliminating the need for any isolation and purification steps. We have demonstrated that this system can be used for the rapid screening of various CaM antagonists that are potential antipsychotic drugs.

Liquid-phase microextraction for rapid AP-MALDI and quantitation of nortriptyline in biological matrices.

A liquid-phase microextraction (LPME) method using a micropipette with disposable tips was demonstrated for coupling to atmospheric pressure MALDI-MS (AP-MALDI/MS) as a concentrating probe for rapid analysis and quantitative determination of nortriptyline drug from biological matrices including human urine and human plasma. This technique was named as micropipette extraction (MPE). The best optimized parameters of MPE coupled to AP-MALDI/MS experiments were extraction solvent, toluene; extraction time, 5 min; sample agitation rate, 480 rpm; sample pH, 7; salt concentration, 30%; hole size of micropipette tips, 0.61 mm (id); and matrix concentration, 1000 ppm using alpha-cyano-4-hydroxycinnamic acid (CHCA) as a matrix. Three detection modes of AP-MALDI/MS analysis including full scan, selective ion monitor (SIM), and selective reaction monitor (SRM) of MS/MS were also compared for the MPE performance. The results clearly demonstrated that the MS/MS method provides a wider linear range and lower LODs but poor RSDs than the full scan and SIM methods. The LOD values for the MPE under SIM and MS/MS modes in water, urine, and plasma were 6.26, 47.5, and 94.9 nM, respectively. The enrichment factors (EFs) of this current approach were 36.5-43.0 fold in water. In addition, compared to single drop microextraction (SDME) and LPME using a dual gauge microsyringe with a hollow fiber (LPME-HF) technique, the LODs acquired by the MPE method under MS/MS modes were comparable to those of LPME-HF and SDME but it is more convenient than both methods. The advantages of this novel method are simple, easy to use, low cost, and no contamination between experiments since disposable tips were used for the micropipettes. The MPE has the potential to be widely used in the future because it only requires a simple micropipette to perform all extraction processes. We believe that this technique can be a powerful tool for MALDI/MS analysis of biological samples and clinical applications.