Electroless‐coated magnetic three‐dimensional graphene with silver nanoparticles used for the determination of pesticides in fruit samples

A new type of adsorbent composed of magnetic three‐dimensional graphene coated with silver nanoparticles was synthesized by an electroless technique and used in the magnetic solid‐phase extraction of selected pesticides (fenitrothion, chlorpyrifos, and hexaconazole) before gas chromatography with a micro‐electron capture detector. The adsorbent was characterized using Fourier‐transform infrared spectroscopy, X‐ray diffraction, vibrating sample magnetometry, and field‐emission scanning electron microscopy. The important extraction parameters such as pH, adsorbent dose, extraction time, and desorption conditions were investigated. Under the optimal conditions, the analytical figures of merit were obtained as: linear dynamic range of 0.1–5 ng/g with determination coefficients of 0.991–0.996; limit of detection of 0.07–0.13 ng/g; limit of quantification of 0.242–0.448 ng/g; and the intraday and interday relative standard deviations (C = 5 ng/g, n = 3) were 3.8–8.7 and 6.6–8.9%, respectively. The developed method was successfully applied for analysis of the selected pesticides in tomato and grape with extraction recoveries in the range of 72.8–109.6%.     

A hybrid triazine‐imine core‐shell magnetic covalent organic polymer for analysis of pesticides in fruit samples by ultra high performance liquid chromatography with tandem mass spectrometry

A novel hybrid triazine‐imine core‐shell magnetic covalent organic polymer with high adsorption capacity and excellent stability was fabricated by surface‐assisted in situ growth technique. The composite possesses porous and extended π‐conjugated system, and was applied as the magnetic sorbent for efficient enrichment and rapid separation of pesticides. A new analytical method for simultaneous determination of eight pesticides in fruit samples was developed by magnetic solid phase extraction combined with ultra high performance liquid chromatography and tandem mass spectrometry. The effect of extraction time, desorption time, and the type of desorption solvent on the extraction efficiency were evaluated. The established method shows good repeatability and high sensitivity. The repeatability of this method was estimated with relative standard deviations in the range of 0.7–7.0% (n = 5) for the same batch, and 1.7–10% (n = 3) for batch to batch. Good linearity for eight pesticides was obtained with coefficient of determination in the range of 0.9942–0.9990. Limit of detections ranged from 0.4 to 1.2 ng/L. Real sample determination showed that four and two pesticides were detected in strawberry and grape, respectively. The results demonstrated that the established method was efficient, sensitive, and convenient for trace determination of pesticides in fruit samples.     

Preparation of highly hydrophilic magnetic nanoparticles with anion‐exchange ability and their application for the extraction of non‐steroidal anti‐inflammatory drugs in environmental samples

Diallyldimethylammonium chloride modified magnetic nanoparticles were synthesized by the “thiol‐ene” click chemistry reaction. Diallyldimethylammonium chloride rendered the material plenty of quaternary ammonium groups, and thus the excellent aqueous dispersibility and anion‐exchange capability. The novel material was then used as the magnetic solid‐phase extraction sorbent to extract eight non‐steroidal anti‐inflammatory drugs from water samples. Combined with high‐performance liquid chromatography and ultraviolet detection, under the optimal conditions, the developed method exhibited wide linearity ranges (1–1000, 2–1000, and 5–1000 ng/mL) with recoveries of 88.0–108.6% and low limits of detection (0.3–1.5 ng/mL). Acceptable precision was obtained with satisfactory intra‐ and inter‐day relative standard deviations of 0.4–4.4% (n = 3) and 1.1–5.5% (n = 3), respectively. Batch‐to‐batch reproducibility was acceptable with relative standard deviations <9.7%. The hydrophilic magnetic nanoparticle featured with quaternary ammonium groups showed high analytical potential for acidic analytes in environmental water samples.     

Solid‐phase extraction using chloropropyl functionalized sol–gel hybrid sorbent for simultaneous determination of organophosphorus pesticides in selected fruit samples

A new sol–gel hybrid methyltrimethoxysilane‐chloropropyltriethoxysilane was prepared as sorbent for solid‐phase extraction. The extraction efficiency of the prepared sol–gel hybrid methyltrimethoxysilane‐chloropropyltriethoxysilane was assessed by using three selected organophosphorus pesticides, namely, chlorpyrifos, profenofos, and malathion. Gas chromatography–mass spectrometry was used for detection of organophosphorus pesticides. Several vital parameters were optimized to identify the best extraction conditions. Under the optimum extraction conditions, solid‐phase extraction‐methyltrimethoxysilane‐chloropropyltriethoxysilane method showed good linearity range (0.05‐1 μg/mL) with coefficient of determination more than 0.995. The limits of detection obtained were in the range of 0.01–0.07 μg/mL and limits of quantification ranging from 0.03 to 0.21 μg/mL. The limits of detection obtained for the developed method were 2.3–6.5× lower than the limits of detection of commercial octadecyl silica sorbent. Real samples analysis was carried out by applying the developed method on red apple and purple grape samples. The developed method exhibited good recoveries (88.33–120.7%) with low relative standard deviations ranging from 1.6 to 3.3% compared to commercial octadecyl silica sorbent, which showed acceptable recoveries (70.3–100.2%) and relative standard deviations (6.3–8.8%). The solid‐phase extraction‐methyltrimethoxysilane‐chloropropyltriethoxysilane method is presented as an alternative extraction method for determination of organophosphorus pesticides.     

Magnetic core micelles as a nanosorbent for the efficient removal and recovery of three organophosphorus pesticides from fruit juice and environmental water samples

Sodium dodecyl sulfate coated amino‐functionalized magnetic iron oxide nanoparticles were used as an efficient adsorbent for rapid removal and preconcentration of three important organophosphorus pesticides, chlorpyrifos, diazinon and phosalone, by ultrasound‐assisted dispersive magnetic solid‐phase microextraction. Fabrication of amino‐functionalized magnetic nanoparticles was certified by characteristic analyses, including Fourier transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy, and transmission electron microscopy. Affecting parameters on the removal efficiency were investigated and optimized through half‐fractional factorial design and Doehlert design, respectively. The analysis of analytes was performed by high‐performance liquid chromatography with ultraviolet detection. Under the optimum conditions, extraction recoveries for 20 ng/mL of organophosphorus pesticides were in the range of 84–97% with preconcentration factors in the range of 134–155. Replicating the experiment in above condition for five times gave the relative standard deviations <6%. The calibration curves showed high linearity in the range of 0.2–700 ng/mL and the limits of detection were in the range of 0.08–0.13 ng/mL. The proposed method was successfully applied for both removal and trace determination of these three organophosphorus pesticides in environmental water and fruit juice samples.     

Graphene‐coated magnetic‐sheet solid‐phase extraction followed by high‐performance liquid chromatography with fluorescence detection for the determination of aflatoxins B1, B2, G1, and G2 in soy‐based samples

A new method named graphene‐coated magnetic‐sheet solid‐phase extraction based on a magnetic three‐dimensional graphene sorbent was developed for the extraction of aflatoxins prior to high‐performance liquid chromatography with fluorescence detection. The use of a perforated magnetic‐sheet for fixing the magnetic nanoparticles is a new feature of the method. Hence, the adsorbent particles can be separated from sample solution without using an external magnetic field. This made the procedure very simple and easy to operate so that all steps of the extraction process (sample loading, washing, and desorption) were carried out continuously using two lab‐made syringe pumps. The factors affecting the performance of extraction procedure such as the extraction solvent, adsorbent dose, sample loading flow rate, ionic strength, pH, and desorption parameters were investigated and optimized. Under the optimal conditions, the obtained enrichment factors and limits of detection were in the range of 205–236 and 0.09–0.15 μg/kg, respectively. The relative standard deviations were <3.4 and 7.5% for the intraday (n = 6) and interday (n = 4) precisions, respectively. The developed method was successfully applied to determine aflatoxins B₁, B₂, G₁, and G₂ in different soy‐based food samples.     

Application of magnetized MOF‐74 to phthalate esters extraction from Chinese liquor

In this study, magnetized MOF‐74 (Ni) was prepared using an ultrasound‐assisted synthesis method. This novel functional magnetic adsorbent was characterized using various techniques. Using the prepared material as adsorbents, a magnetic solid‐phase extraction method coupled with high‐performance liquid chromatography was proposed for determining four phthalate esters in Chinese liquor samples. The extraction parameters, including solution pH, adsorbent amount, extraction time, and eluent type and volume, were optimized. Under the optimized conditions, proposed method showed good linearity within the range of 1.53–200 μg/L for diphenyl phthalate, 2.03–200 μg/L for butyl benzyl phthalate, 7.02–200 μg/L for diamyl phthalate, and 6.03–200 μg/L for dicyclohexyl phthalate, with correlation coefficients > 0.9944, low limits of detection (0.46–2.10 μg/L, S/N = 3), and good extraction repeatability (relative standard deviations of 3.7%, n = 6). This method was successfully used to analyze phthalate esters in Chinese liquor samples with recoveries of 74.4–104.8%. Two phthalate esters were detected in two samples, both at concentrations that satisfied the Chinese national standard, indicating this method has practical application prospects. The extraction efficiency of this method was also compared with conventional solid‐phase extraction using commercial C₁₈ cartridges. The results demonstrated that the proposed magnetic solid‐phase extraction is a simple, time‐saving, efficient, and low‐cost method.     

Determination of trace amounts of aromatic amines after magnetic solid‐phase extraction using silver‐modified Fe3O4/graphene nanocomposite

In this work, a fast and simple magnetic dispersive solid phase extraction methodology was developed utilizing Ag@magnetite nanoparticles@graphene nanocomposite as an efficient magnetic nanosorbent for preconcentration and determine of five aromatic amines in water samples. The sorbent was characterized by diverse characterization techniques. After the extraction, high‐performance liquid chromatography with UV detection was utilized to analysis the aromatic amines. The effects of different factors on the extraction process were studied thoroughly via design of experiment and desirability function. Detection limits and linear dynamic ranges were obtained in the range of 0.10–0.20 and 0.3–300 μg/L, respectively. The relative standard deviations (n = 5) were in the range of 4.3–6.5%. Eventually, the method was employed for determination of target aromatic amines in various water samples.     

Magnetic solid‐phase extraction of benzoylurea insecticides in tea samples with Fe3O4‐hyperbranched polyester magnetic composite as sorbent

In this work, a method for the analysis of benzoylurea insecticides, including hexaflumuron, flufenoxuron, lufenuron and chlorfluazuron, in tea samples by high‐performance liquid chromatography with Fe₃O₄‐hyperbranched polyester nanocomposite as the adsorbent for magnetic solid‐phase extraction was developed. The magnetic nanocomposite was prepared and characterized by infrared spectroscopy, vibrating sample magnetometry, and scanning electron microscopy. The as‐prepared nanocomposite was used as a sorbent for the extraction and preconcentration of pesticide residues in tea samples. The extraction and desorption conditions, including mass ratios of raw materials, amount of sorbent, pH value, extraction time, and desorption time, were investigated. Under the final conditions chosen for the analysis, good linearity was obtained for all the tested compounds, with R² values of at least 0.9979. The limits of detection were determined in the range of 0.15–0.3 μg/L. The recovery obtained from the analysis of tea samples with various spiked concentrations was between 90.7 and 98.4%, with relative standard deviations (n = 4) lower than 4.1%. Furthermore, the present approach was successfully applied to the quantitative determination of residues of benzoylurea insecticides in real samples.     

Dispersive magnetic solid‐phase extraction of phthalate esters from water samples and human plasma based on a nanosorbent composed of MIL‐101(Cr) metal–organic framework and magnetite nanoparticles before their determination by GC–MS

In this study, a magnetic metal–organic framework was synthesized simply and utilized in the dispersive magnetic solid‐phase extraction of five phthalate esters followed by their determination by gas chromatography with mass spectrometry. First, MIL‐101(Cr) was prepared hydrothermally in water medium without using highly corrosive hydrofluoric acid, utilizing an autoclave oven heat supply. Afterward, Fe₃O₄ nanoparticles were decorated into the matrix of MIL‐101(Cr) to fabricate magnetic MIL‐101 nanocomposite. The nanocomposite was characterized by various techniques. The parameters affecting dispersive magnetic solid‐phase extraction efficiency were optimized and obtained as: a sorbent amount of 15 mg; a sorption time of 20 min; an elution time of 5 min; NaCl concentration, 10% w/v; type and volume of the eluent 1 mL n‐hexane/acetone (1:1 v/v). Under the optimum conditions detection limits and linear dynamic ranges were achieved in the range of 0.08–0.15 and 0.5–200 μg/L, respectively. The intra‐ and interday RSD% values were obtained in the range of 2.5–9.5 and 4.6–10.4, respectively. Ultimately, the applicability of the method was successfully confirmed by the extraction and determination of the model analytes in water samples, and human plasma in the range of microgram per liter and satisfactory results were obtained.     

Magnetic amino‐functionalized hollow silica‐titania microsphere as an efficient sorbent for extraction of pesticides in green and roasted coffee beans

This study describes the synthesis and application of a magnetic amino‐functionalized hollow silica‐titania microsphere as a new sorbent for magnetic dispersive micro‐solid phase extraction of selected pesticides in coffee bean samples. The sorbent was fully characterized by Fourier‐transform infrared spectroscopy, field emission scanning electron microscopy, transition electron microscopy, energy‐dispersive X‐ray spectroscopy, and vibrating sample magnetometry techniques. Significant extraction parameters affecting the proposed method, such as extraction time, sorbent amount, sample solution pH, salt amount, and desorption conditions (desorption solvent and time) were investigated and optimized. All the figures of merits were validated in coffee bean samples under the matrix‐matched calibration method. Linear dynamic ranges were 5–250 µg/kg with the determination coefficients (R²) > 0.9980. The limits of detection for the pesticides of chlorpyrifos, malathion, hexaconazole, and atrazine were 1.42, 1.43, 1.35, and 1.33 µg/kg, respectively. Finally, the method was successfully applied for the determination of the pesticides in green and roasted coffee bean samples, and the obtained recoveries were in the range of 74–113% for spiked samples. The prepared sorbent could be used for the magnetic dispersive micro‐solid phase extraction of pesticides in the plant‐derived food matrix.     

Extraction of diclofenac by SiO2‐NH2@Fe3O4 and its determination: Central composite design

In this work, magnetic nanoparticles (Fe₃O₄) were prepared by simple co‐precipitation method in aqueous medium and then subsequently modified with tetraethyl orthosilicate and 3‐aminopropyl triethylenesilane. The properties of the particles were characterized by FTIR spectroscopy X‐ray diffraction, transmission electron microscopy, and scanning electron microscopy. The SiO₂‐NH₂@Fe₃O₄ particles were successfully applied to simultaneously enrich and separate diclofenac from water, urine, and plasma samples. The method, which takes the advantages of both nanoparticle adsorption and magnetic phase separation from the sample solution, could avoid some of the time‐consuming experimental procedures related to the traditional solid phase extraction. The main parameters affecting extraction and desorption efficiency such as pH, amount of SiO₂‐NH₂@Fe₃O₄, volume of desorption solvent, and extraction time were screened. The significant variables were optimized by using central composite design. At optimum conditions values of variables set as pH = 4, 10 mg SiO₂‐NH₂@Fe₃O₄, 0.5 mL methanol, and 15 min extraction time and then the extracted diclofenac were injected to HPLC for analysis. The linear response (r² > 0.9992) was obtained in the range of 0.004–15 µg/mL with detection limit 0.0012 µg/mL and extraction recovery was in the range of 92–96% with RSD < 5% (n = 6).     

Magnetic solid-phase extraction of organophosphorus pesticides from apple juice and environmental water samples using magnetic graphene oxide coated with poly(2-aminoterephthalic acid-co-aniline) nanocomposite as a sorbent

An effective magnetic solid-phase extraction method was proposed using magnetic graphene oxide coated with poly(2-aminoterephthalic acid-co-aniline) as a sorbent for preconcentration and extraction of organophosphorus pesticides from environmental water and apple juice samples, and determined using the gas chromatography-mass spectrometry analysis. To approve the successful synthesis of the magnetic nanocomposite, the prepared sorbent was characterized by field emission scanning electron microscopy, X-ray diffraction, vibrating sample magnetometer, and Fourier transforms infrared techniques. The main parameters affecting the extraction efficiency were considered and studied to afford an optimized procedure. Systematic method validation verified its suitable recoveries (89.4–107.3%), and precision (relative standard deviations < 6.8%). The method showed a wide linear dynamic range (0.04–700 ng/mL) with low limits of detection (0.01–0.06 ng/mL) and quantification (0.04–0.21 ng/mL). This method presented good potential and great sensitivity for the pesticides determination.     

Synthesis of polydopamine‐functionalized magnetic graphene and carbon nanotubes hybrid nanocomposites as an adsorbent for the fast determination of 16 priority polycyclic aromatic hydrocarbons in aqueous samples

A novel adsorbent made of polydopamine‐functionalized magnetic graphene and carbon nanotubes hybrid nanocomposite was synthesized and applied to determine 16 priority polycyclic aromatic hydrocarbons by magnetic solid phase extraction in water samples. FTIR spectroscopy, transmission electron microscopy, scanning electron microscopy, and Raman spectroscopy consistently indicate that the synthesized adsorbents are made of core–shell nanoparticles well dispersed on the surface of graphene and carbon nanotubes. The major factors affecting the extraction efficiency, including the pH value of samples, the amount of adsorbent, adsorption time and desorption time, type and volume of desorption solvent, were systematically optimized. Under the optimum extraction conditions, a linear response was obtained for polycyclic aromatic hydrocarbons between concentrations of 10 and 500 ng/L with the correlation coefficients ranging from 0.9958 to 0.9989, and the limits of detection (S/N = 3) were between 0.1 and 3.0 ng/L. Satisfactory results were also obtained when applying these magnetic graphene/carbon nanotubes/polydopamine hybrid nanocomposites to detect polycyclic aromatic hydrocarbons in several environmental aqueous samples.     

Electrospun magnetic polybutylene terephthalate nanofibers for thin film microextraction

A thin film microextraction method using elecrospun magnetic polybutylene terephthalate nanofibers is developed and implemented to isolate some selected triazines. Due to the high mechanical stability of these nanofibers, they are repeatedly used under harsh magnetic stirring and ultrasonic conditions without any damage and structure degradation. The presence of magnetic nanoparticles within the nanofiber structure increases the extraction efficiency while the fibers could be collected by an external magnet. The synthesized nanocomposite showed strong affinity toward the selected analytes. Apart from the concentration of magnetic nanoparticles within the nanocomposite network, the effect of different parameters on the extraction and desorption processes including the sample pH, extraction time, sample volume, type of desorption solvent, solvent volume, and desorption time were optimized. Eventually, the detection limits were in the range of 0.02–0.05 ng/mL, while the limits of quantification were between 0.1 and 0.2 ng/mL. The linear dynamic range was 0.1–100 ng/mL, and the relative standard deviations were 4–9% (n =  3). The developed method was extended to the real water samples, and the relative recoveries were in the range of 86–103%, indicating that the prepared sorbent is suitable for extraction of triazines from environmental samples.     

Liquid chromatographic determination of trace levels of nitrophenols in water samples after dispersive magnetic solid phase extraction

An efficient and fast dispersive magnetic solid phase extraction method was developed using MIL‐101(Cr)/poly (mercaptobenzothiazole)@magnetite nanoparticles for the preconcentration and determination of nitrophenols in river and rain water samples. High‐performance liquid chromatography‐Ultraviolet instrument was applied for the analysis of target nitrophenols. The effect of several variables on the extraction performance was explored via design of experiment approach. Limits of detection and linear dynamic ranges were attained in the range of 0.05–0.10 µg/L and 0.2–250 µg/L, respectively. The enrichment factors were in the range of 317–363. The precision (n = 3) of dispersive magnetic solid phase extraction method was in the range of 5.3–6.8%. Eventually, the method was utilized for the analysis of target nitrophenols in river and rain water samples.     

Fe3O4 nanoparticles coated with polyhedral oligomeric silsesquioxanes and β‐cyclodextrin for magnetic solid‐phase extraction of carbaryl and carbofuran

In this study, porous sandwich structure Fe₃O₄ nanoparticles coated by polyhedral oligomeric silsesquioxanes and β‐cyclodextrin were prepared by surface polymerization and were used as the magnetic solid phase extraction adsorbent for the extraction and determination of carbaryl and carbofuran. The Fe₃O₄ nanoparticles coated with polyhedral oligomeric silsesquioxanes and β‐cyclodextrin were characterized by Fourier transform infrared spectroscopy, X‐ray diffraction, thermogravimetric analysis, vibrating sample magnetometry, and scanning electron microscopy. After optimizing the extraction conditions, a method that combined magnetic solid phase extraction with high‐performance liquid chromatography was developed for the determination of carbaryl and carbofuran in apple. The method exhibited a good linearity in the range of 2–400 μg/kg for carbaryl and carbofuran (R² = 0.9995), respectively. The limits of detection were 0.5 μg/kg of carbaryl and 0.7 μg/kg for carbofuran in apple, respectively. Extraction recoveries ranged from 94.2 to 103.1% with the preconcentration factor of 300 and the relative standard deviations were less than 5.9%. These results indicated that the method combined magnetic solid phase extraction with high‐performance liquid chromatography and was promising for the determination of carbaryl and carbofuran at trace amounts.     

An efficient cleanup method coupled with gas chromatography and mass spectrometry for multi‐pesticides residue analysis in complex plant matrices

We aimed to develop an efficient cleanup method for multi‐pesticides residue analysis in complex plant matrices, shallot, ginger, garlic, onion, leek, and celery. Column chromatography was used as the cleanup method and fabricated with florisil and graphitized carbon black as the adsorbents. The amount of the graphitized carbon black adsorbent and the choice of the elution solvent were systematically investigated for exploring the best combination. The target pesticides covered organochlorine, pyrethroid, and organophosphorus pesticides, and were 38 in total. The method validation and comparison were performed to verify its feasibility and advantages in operation convenience and purification efficiency. The method limit of quantitation varied from 0.01 to 0.03 mg/kg, which depends on the pesticides and the sample matrices. The recoveries of the pesticides ranged from 60.5 to 128% (RSD ≤ 19.0%) at the spiked concentration level of 0.01 (or 0.03) mg/kg and 62.9 to 130% (RSD ≤ 13.0%) at 0.1 mg/kg. Compared with the commercial cleanup solid‐phase extraction cartridges, the present adsorbent combination displayed better purification effect and shorter sample pretreatment time, demonstrating potential application prospect in the complex matrix sample analysis.     

Determination of organophosphorus pesticides by gas chromatography with mass spectrometry using a large‐volume injection technique after magnetic extraction

A fast and efficient method was developed for the extraction and determination of organophosphorus pesticides in water samples. Organophosphorus pesticides were extracted by solid‐phase extraction using magnetic multi‐walled carbon nanotubes and determined by gas chromatography with ion‐trap mass spectrometry. Parameters affecting the extraction were investigated. Under optimum conditions of the method, 10 mg magnetic multi‐walled carbon nanotubes were added into 10 mL sample. After 2 min, adsorbent particles settled at the bottom of test tube with a magnet. After removing aqueous supernatant, the analytes were desorbed with acetonitrile. Then, 70 μL of acetonitrile phase was injected into the gas chromatography and mass spectrometry system that had an ion‐trap analyzer. To achieve high sensitivity, the large‐volume‐injection technique was used with a programmed temperature vaporization inlet, and the ion‐trap mass spectrometer was operated in single ion storage mode. Under the best conditions, the enrichment factors and extraction recoveries were in the range of 113–124 and 74–103%, respectively. The limits of detection were between 3 and 15 ng/L, and the relative standard deviations were < 10%. This method was successfully used for the determination of organophosphorus pesticides in dam water, lagoon water, and river water samples with good reproducibility and recovery.     

Magnetic micro‐solid‐phase extraction based on magnetite‐MCM‐41 with gas chromatography–mass spectrometry for the determination of antidepressant drugs in biological fluids

A new facile magnetic micro‐solid‐phase extraction coupled to gas chromatography and mass spectrometry detection was developed for the extraction and determination of selected antidepressant drugs in biological fluids using magnetite‐MCM‐41 as adsorbent. The synthesized sorbent was characterized by several spectroscopic techniques. The maximum extraction efficiency for extraction of 500 μg/L antidepressant drugs from aqueous solution was obtained with 15 mg of magnetite‐MCM‐41 at pH 12. The analyte was desorbed using 100 μL of acetonitrile prior to gas chromatography determination. This method was rapid in which the adsorption procedure was completed in 60 s. Under the optimized conditions using 15 mL of antidepressant drugs sample, the calibration curve showed good linearity in the range of 0.05–500 μg/L (r ² = 0.996–0.999). Good limits of detection (0.008–0.010 μg/L) were obtained for the analytes with good relative standard deviations of <8.0% (n  = 5) for the determination of 0.1, 5.0, and 500.0 μg/L of antidepressant drugs. This method was successfully applied to the determination of amitriptyline and chlorpromazine in plasma and urine samples. The recoveries of spiked plasma and urine samples were in the range of 86.1–115.4%. Results indicate that magnetite micro‐solid‐phase extraction with gas chromatography and mass spectrometry is a convenient, fast, and economical method for the extraction and determination of amitriptyline and chlorpromazine in biological samples.