Solid-phase Microextraction Procedure Research Articles

Development of a dispersive micro-solid phase extraction method based on using cobalamin as a green adsorbent for the extraction of Cd(II) and Pb(II) from oil samples

ABSTRACT A dispersive micro-solid phase extraction procedure using cobalamin as a green sorbent has been developed for the extraction of Cd(II) and Pb(II) ions from oil samples. At first, a desired amount of oil sample was dissolved in chloroform. Then, the specified amount of cobalamin was added and vortexed. After centrifuging, the separated solid particles were dissolved in nitric acid solution. Finally, the analytes were analysed by flame atomic absorption spectrometry. Effects of different analytical parameters such as amounts of sample and cobalamin, vortex time, complexing agent amount, type and volume of dissolving solvent, and temperature on the extraction efficiency of Pb(II) and Cd(II) ions were investigated and optimised. Under optimised conditions, calibration curves were established with the linear ranges of 1.5–150 μg Kg−1 for Cd(II) and 1–150 μg Kg−1 for Pb(II). The detection limits were found to be 0.48 and 0.34 µg Kg−1 along with extraction recoveries of 89.1% and 94.8% for Cd(II) and Pb(II) ions, respectively. The proposed method demonstrated good repeatability, with the relative standard deviation ranging from 3.8% to 4.1% (n = 6, C = 10 μg Kg−1 of each cation). Finally, the method was successfully applied to determine the concentrations of Cd(II) and Pb(II) ions in various oil samples.

Design and construction of pilot sludge drying package for the excess sludge in petrochemical industries: Heavy metals determination in sludge by polarography and atomic absorption spectrometry

In this research, according to the high amount of sludge in a petrochemical company, an iron package type of drying sludge bed was made/designed with carbon steel. Then, the drying sludge pond was filled with layers of sand with different mesh sizes. The excess sludge from the sedimentation pond was passed over this bed, and the amount of sludge removed by the bed was obtained at %96. The values of heavy metal and microbial forms were determined using the proposed method based on activated sludge after wastewater treatment. For the validation process, 10 mL of deionized water (DW) was mixed with 1.0 g of dried sludge with pure nitric acid (2% HNO3), and then the solid phase was filtered with the Whatman filter (WF). The concentration of heavy metals (As, Cd, Cu, Pb, Hg, Mo, Ni, Co, Se, Zn) in the remaining solution of sludge (mg kg-1) and wastewater (µg L-1) was extracted/ separated based on sulfur-doped graphene oxide adsorbent (SDGO) by solid-phase microextraction procedure (SPME) before being determined by the flame and hydride generation atomic absorption spectrometry (F-AAS; HG-AAS) which had similar range to the polarography analysis. The LOD, linear range and preconcentration factor (PF) for metals were obtained.

Ultra-Sensitive Determination of Cadmium in Food and Water by Flame-AAS after a New Polyvinyl Benzyl Xanthate as an Adsorbent Based Vortex Assisted Dispersive Solid-Phase Microextraction: Multivariate Optimization.

Background: Cadmium (Cd) is a very toxic and carcinogenic heavy metal even at low levels and it is naturally present in water as well as in food. Methods: A new polyvinyl benzyl xanthate (PvbXa) was synthesized and used as a new adsorbent in this work. It contains pendant sulfide groups on the main polystyryl chain. Using this new adsorbent, PvbXa, a vortex-assisted dispersive solid-phase microextraction (VA-dSPµE) procedure was developed for the determination of cadmium from food and water samples via flame atomic absorption spectrophotometry (FAAS). Synthesized PvbXa was characterized by 1H Nuclear magnetic resonance (NMR) Spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR), and X-ray Photoelectron Spectroscopy (XPS). The different parameters of pH, sample volume, mixing type and time, sorbent amount, and eluent time were optimized using standard analytical methods. Results: The optimized method for assessment of Cd in food and water samples shows good reliability. The optimum conditions were found to be a 0.20-150 µg L-1 linear range, 0.06 µg L-1 LOD, 0.20 µg L-1 LOQ, 4.3 RSD %, and a preconcentration factor of 160. Conclusions: The statistically experimental variables were utilized using a central composite design (CCD). The present method is a low-cost, simple, sensitive, and very effective tool for the recovery of Cd.

Oxygen-doped graphite carbon nitride as a fiber coating material for headspace solid-phase microextraction of organic phosphate esters

Efficient enrichment of trace organic phosphate ester (OPEs) pollutants from complex matrixes is essential for chromatographic analysis. Herein, oxygen-doped graphite carbon nitride (denoted as O-g-C3N4) was fabricated though thermal polycondensation of urea using H2O2 as an oxygen source. The resulting O-g-C3N4 material was loose and had homogeneous pores structure, with a specific surface area of 73.74 m2/g. The O-g-C3N4 was served as fiber coating material to create solid phase microextraction (SPME) device, with silica sol as adhesive for OPEs determination. Owing to the well-developed porosity of O-g-C3N4, which provides effective mass transfer channels for OPEs, the whole SPME procedure could be accomplished within 25 min. The O-g-C3N4 fiber coating offers excellent mechanical strength and high stability and being workable after 180 sampling. The developed approach revealed a good linearity for OPEs in ultrapure water at the concentrations of 0.01–100 µg/L with the LODs between 0.001 µg/L and 0.003 µg/L. In addition, relative recoveries of 85.24% ∼99.73% were achieved in tap water and river water. These findings suggested that the oxygen-doped g-C3N4 material has potential for headspace SPME of trace OPEs in various matrixes.

GC/EI-MS and UV-Vis analysis of pesticide residues in cultivated Catha edulis Forsk (Khat) from selected farms in Meru County, Kenya

In this study, an analysis of pesticide residues was performed using a gas chromatography/ electron impact mass spectrometer (GC/EI-MS) to qualitatively assess and characterize pesticide residues in khat leaves sampled from selected agricultural farms in Meru County, Kenya. A solid-phase microextraction (SPME) procedure followed by GC/EI-MS analysis led to the detection and identification of six pesticide compounds from the sample-ion chromatograms. They include cypermethrin, acephate, cyhalothrin, cyfluthrin, chlorpyrifos, and chlorfenvinphos. The prevalence rate of pesticide contamination was determined to be 54.5% of the sample size. Of the identified pesticide residues, 50% were compounds based on pyrethroids and the other 50% were based on organophosphate. Four of the six identified pesticides were chlorinated compounds. A quick, easy, cheap, effective, rugged, and safe UV-vis double beam spectrophotometric technique based on copper (II) chelation reactions leading to colored copper pesticide complexes was developed, validated, and applied to quantify and compare the levels of selected pesticide compounds found in the khat samples. UV-vis wavelength-scan measurements performed on pesticide compounds chelated with copper (II) ions revealed maximum absorption of Cu-cypermethrin and Cu-acephate at 321 and 207 nm, respectively. The standards calibration curves developed from the UV-Vis quantitation technique showed excellent linearity in the concentration range of 0.5-10.0 µg/L (R2 = 0.99) for both cypermethrin and acephate standards. The estimated limits of quantification (LOQ) were 0.25-0.26 µg/L, respectively. The UV-Vis quantitation results from the selected samples (in which residues were confirmed to be present) revealed that acephate (an organophosphate residue) occurred at higher concentration levels (range 2.897-7.978 µg/L) than cypermethrin (2.145 µg/L). For the pesticides quantitatively analysed in the selected samples, the levels were below the maximum residue limit (MRL). The hazard quotients (HQ) were in the range of between 0.247-0.797.

Use of a simple magnetic material for the determination and speciation of very low amounts of silver and gold

Silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs) can be separated of their ions by a magnetic dispersive micro-solid phase extraction procedure using non-functionalised ferrite particles. The separation and speciation are based on careful control of the acidity of the medium, without involving oxidation-reduction processes. Thus, using a small amount of ferrite particles (2 mg for a typical 10 mL sample) which is added to the sample as a suspension, Ag(I) as well as both gold species are retained in the sorbent at pH 4, while AgNPs are retained at pH 8. For the selective retention of AuNPs, ammonium diethyl dithiophosphate is added to the medium and the extraction process is repeated at pH 4. In all cases, the analytes are desorbed by treating the solid phase separated by the magnet with 0.1 mL of a thiourea solution at pH 3 and determined by electrothermal atomization atomic absorption spectrometry. For the measurement of silver, a palladium salt is used as a chemical modifier. This is not required for the determination of gold. The enrichment factor is 97 and the detection limits are 12 and 4 ng L−1 for gold and silver, respectively. The reproducibility is close to 5% for the four analytes studied. The reliability of the procedures is checked by standard additions and by the use of four standard reference materials with certified total silver content. Several water samples are analysed, and speciation results are given.

An immobilization of aminopropyl trimethoxysilane-phenanthrene carbaldehyde on graphene oxide for toluene extraction and separation in water samples

A new functionalized Nano graphene with aminopropyl trimethoxysilane-phenanthrene-4-carbaldehyde (NGO@APTMS-PNTCA) as a novel adsorbent was used to extract toluene from water samples by the ultrasound-assisted dispersive solid-phase microextraction procedure (USA-D-SPME). So, 50 mg of NGO@APTMS-PNTCA adsorbent was added to water samples and sonicated for 20 min. After toluene extraction, the NGO@APTMS-PNTCA adsorbent separated from the liquid phase with a Whatman membrane filter (200 nm). Then, the toluene was back-extracted from the adsorbent by 2.0 mL of the acetone/ethanol (1:1, eluent) at 25 °C. Due to the physical properties and structure of toluene, fluorobenzene was used as an internal standard. Finally, the toluene values were measured by a gas chromatography-flame ionization detector (GC-FID). In optimized conditions, the limit of detection (LOD), the working range (WR), and the enrichment factor (EF) were obtained at 2.5 μg L−1, 0.01–1.2 mg L−1, and 9.63, respectively (MRSD% = 3.38). Also, the limit of quantification (LOQ) 10 μg L−1 and extraction recovery of more than 95% was efficiently achieved for toluene. Standard additions of toluene to blank solutions had high recoveries between 95.2% and 104.5% with a relative standard deviation (RSD%) of 0.27–5.2. The absorption capacities of NGO and NGO@APTMS-PNTCA adsorbents for toluene extraction were obtained at 32.8 mg g−1 and 154.9 mg g−1, respectively. The USA-D-SPME method was validated by spiking the standard concentrations of toluene. The proposed method demonstrated relevant and suitable statistical results with high accuracy and precision for toluene extraction by a novel adsorbent synthesis.

Solid-phase microextraction of endogenous metabolites from intact tissue validated using a Biocrates standard reference method kit

Improved analytical methods for the metabolomic profiling of tissue samples are constantly needed. Currently, conventional sample preparation methods often involve tissue biopsy and/or homogenization, which disrupts the endogenous metabolome. In this study, solid-phase microextraction (SPME) fibers were used to monitor changes in endogenous compounds in homogenized and intact ovine lung tissue. Following SPME, a Biocrates AbsoluteIDQ assay was applied to make a downstream targeted metabolomics analysis and confirm the advantages of in vivo SPME metabolomics. The AbsoluteIDQ kit enabled the targeted analysis of over 100 metabolites via solid-liquid extraction and SPME. Statistical analysis revealed significant differences between conventional liquid extractions from homogenized tissue and SPME results for both homogenized and intact tissue samples. In addition, principal component analysis revealed separated clustering among all the three sample groups, indicating changes in the metabolome due to tissue homogenization and the chosen sample preparation method. Furthermore, clear differences in free metabolites were observed when extractions were performed on the intact and homogenized tissue using identical SPME procedures. Specifically, a direct comparison showed that 47 statistically distinct metabolites were detected between the homogenized and intact lung tissue samples (P < 0.05) using mixed-mode SPME fibers. These changes were probably due to the disruptive homogenization of the tissue. This study's findings highlight both the importance of sample preparation in tissue-based metabolomics studies and SPME's unique ability to perform minimally invasive extractions without tissue biopsy or homogenization while providing broad metabolite coverage.

A review: Total vaporization solid-phase microextraction procedure in different matrixes

Total vaporization solid-phase microextraction (TV-SPME) is a type of extraction technique in which a specific solvent dissolves the analyte. Then a tiny amount of solvent is taken to the vial of SPME. Then, the solvent vaporizes in the SPME vial, and sampling is carried out on the headspace of the SPME fiber. As a result, the partitioning phase of the analyte between the headspace and liquid sample is omitted. The equilibrium phase remains the analyte partitioning between the headspace and SPME. TV-SPME was introduced in 2014 by Goodpaster to increase the recovery compared to the liquid injection method. This review discusses different aspects of TV-SPME, including its impact on sampling techniques, theoretical part, sampling procedure, and method optimization. Special attention was paid to its applications. A comprehensive literature study was conducted in the relevant databases to summarize the research work that has been done on this technique. In TV-SPME, the liquid samples completely vaporized and had a less matrix effect and better adsorption. This method needs no sample preparation, consumes less supply, and can be done automatically. Also, TV-SPME enables a cost-effective and efficient extraction for different matrixes. This review summarizes aspects related to TV-SPME.

Improved solid-phase microextraction extraction procedure to detect trace-level epichlorohydrin in municipal water systems by HS-SPME-GC/MS.

Epichlorohydrin (ECH) is toxic to humans via multiple routes and is a potential carcinogen. The accurate measurement of ECH at trace level (<0.1 μg/L) is still an obstacle hindering the monitoring and regulation of municipal water systems. In this study, an improved headspace solid-phase microextraction (HS-SPME) procedure is developed and optimized to extract and enrich ECH with high sensitivity, accuracy, and precision. A total 17.4-time enhancement in extraction efficiency is achieved compared with the default condition. Specifically, the AC/PDMS/DVB fiber offered a 4.4-time enhancement comparing with the PDMS/DVB fiber. The effects of different mineral salts in SPME were studied and it was found that an addition of 3 g Na₂SO₄ in the SPME head achieved an additional 3.3-time increase. The pattern how sodium sulfate enhanced ECH extraction by salting out is discussed. The optimization of extraction conditions (pH = 7, 35°C, and 20 min extraction duration) brought another 1.2 times further. Combined with gas chromatography with mass spectrometry, the optimized method exhibits curve linearity in the range of 0.02–1.00 μg/L with an R2 of 0.998. The limit of detection, precision, and accuracy of the method are 0.006 μg/L, 2.6%–5.3%, and −3.5% to −2.0%, respectively. The recovery of ECH spiking in tap water and surface water was investigated, with recovery rates of 88.0%–116% and 72.5%–108%, respectively. Adhering to the requirements of existing water quality regulations, our method shows a high potential to be applied in drinking water quality monitoring and water treatment process assessment.

Dietary intakes of trihalomethanes and haloacetic acids from ready-to-eat vegetables in taiwan.

Chlorine-based disinfectants are often used to sanitize fruit and vegetables to produce a product called ready-to-eat (RTE) vegetables. During the disinfection process, disinfection byproducts (DBPs), such as trihalomethanes (THMs) and haloacetic acids (HAAs), might be formed via chlorination. To determine the amounts of DBPs that occur in RTE vegetables in Taiwan, an analytical method which can detect THMs and HAAs simultaneously was developed for this study. For HAAs, dimethyl sulfate (DMS) was first added into the sample as derivatization reagent and tetrabutylammonium hydrogen sulfate (TBA-H2SO4) was used as the ion-pairing agent to improve the derivatization process. Afterwards, the solid-phase microextraction (SPME) procedure coupled with gas chromatography with tandem mass spectrometers (GC/MS/MS) was performed to measure the HAAs derivatives and THMs in the sample. A total of 92 single RTE ingredients were analyzed in this study. Among various THMs and HAAs, the results showed that dibromochloromethane (21%) and dichloroacetic acid (12%) had the highest detection rates, respectively. Compared with fruits, vegetables were more easily to contain DBPs. For adults in Taiwan, the maximum daily exposure of THMs and HAAs estimated via the consumption of RTE vegetables were 28.53 and 77.83 μg, respectively. The findings from this study suggest that the exposure of DBPs from RTE vegetables is an important food safety issue in Taiwan.

Amylodextrin hydrogel as a green sorbent for pipette-tip micro-solid phase extraction followed by ion mobility spectrometry for analysis of triazole fungicides in environmental water samples

Triazole compounds have been globally used for controlling fungal diseases such as rusts, powdery mildew, and many leaf-spotting fungi. These compounds also have adverse effects on the environment and human health. In the present work, a hydrogel-based sorbent was synthesized by a combination of hydrophilic acrylic polymer and biodegradable amylodextrin. The sorbent was characterized by Fourier-transform infrared (FT-IR) spectroscopy, Brunauer-Emmett-Teller (BET) surface area, elemental CHN analysis, field emission scanning electron microscopy (FE-SEM), and zeta potential. The synthesized hydrogel was used as a green sorbent in the pipette-tip micro-solid phase extraction procedure for extraction and quantification of triazole fungicides (penconazole, hexaconazole, and tebuconazole) in environmental water samples. The corona discharge-ion mobility spectrometry (CD-IMS) was used as a rapid and sensitive detection technique. The effects of important variables on the extraction efficiency were optimized by response surface methodology (RSM). The proposed method provided good linearity (r2 ≥ 0.995) over a concentration range of 0.5–1000 ng/mL, acceptable intra-day RSD (≤ 5.7%, n = 5) and inter-day RSD (≤ 8.7%, n = 5), low limits of detection (0.10–0.20 ng/mL), good preconcentration factors (16.9–17.9 times), and high extraction recoveries (93.1–98.3%) under optimum extraction conditions. The extraction conditions were as follows: the amount of sorbent: 6.0 mg, pH of sample solution: 7.5, the flow rate of sample solution: 2.0 mL/min, adsorption time: 16.5 min, volume of desorption solvent: 1.1 mL, the flow rate of desorption solvent: 0.5 mL/min, and desorption time: 11.7 min. Finally, the proposed method was successfully applied for the quantification of triazoles in river and agricultural water samples.

Enhanced adsorption/extraction of bisphenols by pyrrolic N-based 3D magnetic carbon nanocomposites for effervescence-assisted solid-phase microextraction of bisphenols from juices and the underlying interaction mechanisms

Herein, we fabricated a magnetic 3D nanocomposite based on Co,Ni-codoped and N-modified carbon nanotubes and reduced graphene (CoNi-N-CNTs/rGO). This nanomaterial possessed strong magnetism due to the presence of Co-Ni alloy, abundant defect sites owing to N doping, and a 3D multi-porous structure resulting from CNT in-situ growth on the graphene surface. Based on DFT calculations, H-bonding, hydrophobic and π-π conjugation were inferred to facilitate bisphenol adsorption by nanocomposites, among which π-π interactions provided the greatest adsorption contribution within a given N-doping type. By employing BPM as model compound, the adsorption energies (ΔEa) for π-π conjugation were −1.80, −1.59 and −2.08 eV for graphitic-N, pyridinic-N, and pyrrolic-N, respectively. This infers that pyrrolic-N sites form the strongest BP sorption bonds with the nanocomposite. The nanocomposites were utilized as an extractant in an effervescence tablet-assisted magnetic solid-phase microextraction (ET-MSPE) procedure that was optimized using Plackett-Burman design (PBD) and central composite design (CCD). Under optimized conditions, the ET-MSPE/HPLC-FLD method provided strong analytical performance for quantification of six BPs in juice with limits of detection of 0.06–0.20 μg/L, recoveries of 82.4–103.7 % and RSDs of 1.2–5.3 %. The particular novelty of this study lies in demonstrating the enhancement of adsorption/extraction efficiencies for BPs by nanocomposites resulting from N doping to generate the superior adsorption properties associated with the pyrrolic-N structure. These findings provide a theoretical foundation to inform the rational design of N-doped adsorbents/extractants based on a rigorus understanding of the molecular interactions occurring between carbon-based nanocomposites and BP analogues.

Preparation of electrospun polyacrylonitrile/ϒ-cyclodextrin metal–organic framework nanofibers for extraction of multi-classes herbicides from cereal samples before HPLC-UV analysis

This study employed thin-film solid-phase microextraction procedure as a simple, sensitive, green, and solvent-free method for the co-extraction of multi-classes herbicides from cereal samples before HPLC-UV analysis. To provide an efficient sorbent, electrospun nanofibers of the crosslinked polyacrilonitril/ϒ-cyclodextrin-metal–organic framework (PAN/ϒ-CD-MOF) were successfully fabricated and assessed as a new thin-film adsorbent. Under the optimal conditions (desorption solvent: acetonitrile, desorption time: 5 min, sample solution pH: 7.0, salt concentration: 15% (w/w), and extraction time: 15 min), good linearity in the range of 2.5–1250.0 ng/mL (r2 ≥ 0.992) was obtained. The detection limits were 0.75–2.50 ng/mL. The extraction recoveries and relative recoveries were 64.9–75.7% and 92.9–106.1%, respectively. The method showed good precision as the relative standard deviations were ≤ 6.3%. Finally, the developed method was applied efficiently for trace analysis of the herbicides in wheat, rice, and barley samples. Generally, the proposed method provided a simple, sensitive, environmentally friendly, and relatively fast approach.

Simultaneous determination of trace level riot control agents in environmental water by solid‐phase microextraction and gas chromatography coupled with a flame ionization detector

In this paper, a direct immersion solid-phase microextraction procedure for the simultaneous analyses of four primary riot control agents: 2-chloroacetophenone, o-chlorobenzylidene malonitrile, dibenz(b,f)-1,4-oxazepine, and oleoresin capsicum at μg/L concentration from environmental water was developed. Several parameters that influence the extraction effectiveness were investigated, including fiber type, extraction temperature, extraction time, starring rate, and salinity. Under the recommended conditions, the optimized method had reasonable linearity and accuracy. The average recovery of this method ranged from 84 to 108.1%. The limit of detection for all the analytes ranged from 0.2 to 3 μg/L and the limit of quantification ranged from 1 to 10 μg/L, respectively. A relative standard deviation from 3.0 to 4.3% can be achieved depending on the compounds. The procedure was applied to analyze all the four riot control agents simultaneously in several environmental samples.

A sustainable approach for the stability study of psychotropic substances using vitreous humor and liver as alternative matrices

The stability of psychotropic substances representing various drug groups important from the perspective of forensic chemistry, including benzodiazepines, antidepressants, carbamazepine, cocaine, and their selected metabolites, was investigated for 1 month in two alternative biological matrices, vitreous humor and liver homogenate. Three different thermal storage conditions (−20, 4, and 20 °C) were tested. Liquid chromatography-mass spectrometry (LC-MS) analysis was preceded by an effective solid-phase microextraction (SPME) procedure. The results were statistically analyzed using one-way ANOVA to find significant concentration variations over time. The results obtained allowed for dividing the analytes into four groups: stable under all tested conditions, only at −20 and 4 °C, only at 20 °C, and overall unstable. Nordiazepam, venlafaxine, and cocaine and its metabolites turned out to be the most unstable substances, while fluoxetine showed the highest storage stability in both matrices. The SPME/LC-MS method was comprehensively evaluated according to the principles of white analytical chemistry (WAC), which reconcile the greenness and functionality of the method. A close to 100% whiteness score proves its sustainability and suitability for the intended application.Graphical abstract

Determination of Nitrofuran Metabolites in Complex Food Matrices Using a Rough, Cheap, Easy-Made Wooden-Tip-Based Solid-Phase Microextraction Probe and LC-MS/MS

In this study, a rough, cheap, easy-made wooden-tip-based solid-phase microextraction (SPME) probe was first developed for simultaneous determination of 4 nitrofuran metabolite derivatives in complex food matrices via LC-MS/MS. A simple dip-coating method was used to coat wooden tips with biocompatible polyacrylonitrile (PAN) and N-vinylpyrrolidone-co-divinylbenzene, also known as HLB particles, which served as the extractive substrate in the proposed device. Compared with the traditional solid-phase extraction (SPE) method, the proposed device shortens sample clean-up time, reduces solvent consumption, and decreases testing costs. In addition, the main parameters affecting the SPME procedure efficiency were investigated in detail and the optimal conditions were found. The method was validated using three different food matrixes (pork, croaker, and honey) by spiking with the four metabolites at 0.5, 1.0, and 5.0 μg/kg, as well as their internal standards. The average recovery of all nitrofuran metabolite derivatives ranges from 97.4–109.5% (pork), 87.5–112.7% (croaker), and 98.6–109.0% (honey). Relative standard deviations were all &lt;10% for intraday and interday precision. The values of limit of detection and limit of quantification were, respectively, ranging from 0.011 to 0.123 and 0.033 to 0.369 μg/kg (pork), 0.009 to 0.112 and 0.027 to 0.339 μg/kg (croaker), and 0.010 to 0.131 and 0.030 to 0.293 μg/kg (honey). The presented method was applied to the analysis of real positive samples.

Effect of two types of ozone treatments on the quality of apple fruits

Abstract The aim of this research was to demonstrate the effect of the ozonation process (exposure to ozone in gaseous form and rinsing in water saturated with ozone) on selected apple parameters. The scope of the study included: conducting the ozonation process under controlled conditions at a concentration of 1 ppm and exposure times of 1, 5 and 10 min (ozone in gaseous form) and 10, 15 and 30 min (ozonated water), respectively; polyphenols research; determining antiradical activity using ABTS radicals; and determining the influence of the applied method on the volatiles that give rise to odor chemicals (fragrance and aroma). In both cases, measurements were taken 24 hours after the ozonation process. Both exposure to ozone in gaseous form and washing in ozonated water did not adversely affect the appearance of the fruit. The rinsing process in ozonated water did not significantly affect the composition of the compounds responsible for the fruit’s odor. The proposed washing conditions affected the biochemical balance of the fruit. Differences in polyphenol content and antioxidant potential were noted. The mean content of polyphenols expressed as gallic acid equivalent in the control sample was determined to be 15.22 mg/100 g. In comparing the content of polyphenols with the control sample, insignificant changes in their content were noted, except for the sample with the longest ozonation. In the case of fruit washed within 30 minutes, a significant increase by 53% in antioxidant potential was noted. α- Farnesene was identified as the main component established by headspace solid-phase microextraction (HS-SPME) procedure. The proposed ozonation conditions made it possible to keep the volatile compounds influencing the sensory properties of apples unchanged.

Determination of cobalt and copper in water, plant, and soil samples by magnetite nanoparticle-based solid-phase microextraction (SPME) coupled with microsample injection system-flame atomic absorption spectrometry (MIS-FAAS)

A magnetic solid-phase microextraction (SPME) procedure was optimized using Fe3O4 nanoparticles (NPs) to preconcentrate and determine cobalt and copper in real samples using microsample injection system-flame atomic absorption spectrometry (MIS-FAAS). Recoveries over 95% for Co(II) and 80% for Cu(II) from 90 mL of sample buffered to pH 4.0 were obtained using 50 mg Fe3O4 NPs as the adsorbent and 0.5 mL of 0.5 mol L−1 HNO3 as the eluent. The extraction time was 10 min. The preconcentration factors for Co(II) and Cu(II) were 180. The detection limits for Co(II) and Cu(II) were 1.2 and 0.9 µg L−1, respectively. The relative uncertainties and relative standard deviations were lower than 5.3% and 2.4%, respectively. The developed method was verified by analyzing TMDW-500 drinking water, NIST 1573a Tomato leaves, and NCS DC 78302 Tibet soil as standard reference materials. The spiking experiments provided recoveries exceeding 95%. The method was applied to determine cobalt and copper in water, soil, tea infusion, and vegetable samples.

Evaluation of electrosprayed graphene oxide coatings for elemental analysis by thin film microextraction followed by Laser-induced Breakdown Spectroscopy detection

In this work, a solid phase microextraction procedure, denoted as Thin Film Microextraction (TFME), was combined with Laser-induced Breakdown Spectroscopy for the detection of several analytes in aqueous solutions (Cu, Cr, Ni and Pb). The adsorbent films, consisting of a thin layer of graphene oxide deposited on glass substrates, were generated by using the electrospray deposition technique (ESD). Several parameters affecting the quality and shape of the films resulting from the ESD process were studied, and the morphology and adsorption capacity of the films were evaluated. The generated films were used for extraction of the target analytes from aqueous solutions and, after extraction, the analytes-enriched adsorbents were analysed by LIBS without the need of any desorption or elution step. In order to assess the analytical capability of the TFME-LIBS procedure, different analytical figures of merit of the proposed TFME-LIBS methodology were evaluated. The obtained limits of detection were 14 μg kg−1 for Pb and 15 μg kg−1 for the rest of the tested analytes. Measurement repeatability was better than 4% RSD at low concentration level (20 μg kg−1) but deteriorated by increasing the concentration level at 100 μg kg−1, with %RSD ranging from 3.6% (Cr) to 24% (Pb). Method trueness, evaluated from the analysis of a real sample of bottled water, led to recovery values in the range 85%–106%.