Publications by authors named "Petr Solich"

166 Publications

A simple method to quantify azo dyes in spices based on flow injection chromatography combined with chemometric tools.

J Food Sci Technol 2022 Jul 27;59(7):2764-2775. Epub 2021 Oct 27.

Departamento de Química, INQUISUR, Universidad Nacional del Sur (UNS)-CONICET, Av. Alem 1253, 8000 Bahía Blanca, Argentina.

Para Red (PR) and Sudan dyes have been illegally used as colorants to adulterate certain foods by enhancing their red/orange colour. In addition, they are toxic and carcinogenic. This work presents the development of a simple flow injection chromatographic method combined with chemometric tools to perform the determination of PR, Sudan I (SI) and Sudan II (SII) in food samples. The flow chromatographic system consisted of a low-pressure manifold coupled to a reverse phase monolithic column. A Partial Least Square (PLS) model was applied to resolve overlapped absorption spectra registered for each dye at the corresponding retention time. The relative errors of calibration (RMSECV, %) were 0.49, 0.85 and 0.23, and the relative errors of prediction (RMSEP, %) were 1.12, 0.75 and 0.33 for PR, SI and SII, respectively. The residual predictive deviation (RPD) values obtained were higher than 3.00 for all analytes. The method was successfully applied to quantify the dyes in six different commercial spices samples. The results were compared with the HPLC reference method concluding that there were no significant differences at the studied confidence level (α = 0.05). The proposed method can be used to rapidly determine the analytes in a simple, reliable, low-cost and environmentally-friendly manner.

Supplementary Information: The online version contains supplementary material available at 10.1007/s13197-021-05299-8.
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http://dx.doi.org/10.1007/s13197-021-05299-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC9207011PMC
July 2022

Renewable sorbent dispersive solid phase extraction automated by Lab-In-Syringe using magnetite-functionalized hydrophilic-lipophilic balanced sorbent coupled online to HPLC for determination of surface water contaminants.

Anal Chim Acta 2022 Jun 26;1210:339874. Epub 2022 Apr 26.

Department of Analytical Chemistry, Faculty of Pharmacy in Hradec Králové, Charles University, Akademika Heyrovského 1203, Hradec Králové, 500 05, Czech Republic. Electronic address:

An automated methodology for magnetic dispersive solid phase microextraction integrating bead injection approach for renewable sorbent introduction is presented for the first time and was successfully applied to the enrichment of water contaminants. For this purpose, a simple procedure was developed for the functionalization of commercial SupelTM-Select HLB (Hydrophilic modified styrene polymer) sorbent beads that allowed embedding magnetite nanoparticles (FeO). The sorbent was then used in a dispersive solid phase extraction procedure that was carried out entirely inside the void of an automatic syringe pump following the flow-batch concept of Lab-In-Syringe including automated renewal of the sorbent for each analysis. Mixing processes, sorbent dispersion, and sorbent recovery were enabled by using a strong magnetic stirring bar, fabricated from a 3D printed polypropylene casing and neodymium magnets, inside the syringe. The final extract was submitted to online coupled liquid chromatography with spectrometric detection. System and methodology were applied to determine mebendazole, bisphenol A, benzyl 4-hydroxybenzoate, diclofenac, and triclosan selected as models from different groups of environmental contaminants of current concern. Experimental parameters including extraction and elution times, composition and volume of eluent, and bead recollection were optimized. Required system elements were produced by 3D printing. Enlarging the sample volume by repeated extraction to enhance the sensitivity of the method was studied. Using double extraction from 3.5 mL, limits of detection ranged from 1.2 μg L to 6.5 μg L with an RSD (n = 6) value less than 7% for all the analytes at 25 μg L level. The method was linear in the range of 5-200 μg L and was successfully implemented for the analysis of surface waters with analyte recoveries ranging from 78.4% to 105.6%.
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http://dx.doi.org/10.1016/j.aca.2022.339874DOI Listing
June 2022

Lab-In-Syringe automation of deep eutectic solvent-based direct immersion single drop microextraction coupled online to high-performance liquid chromatography for the determination of fluoroquinolones.

Talanta 2022 Aug 13;246:123476. Epub 2022 Apr 13.

Charles University, Faculty of Pharmacy, Department of Analytical Chemistry, Akademika Heyrovského 1203, 50005, Hradec Králové, Czech Republic. Electronic address:

Lab-In-Syringe direct immersion single drop microextraction is proposed as an automated sample pretreatment methodology and coupled online to HPLC with fluorescence detection for the determination of fluoroquinolones in environmental waters. For the first time, a drop of a natural deep eutectic solvent (NADES), synthesized from hexanoic acid and thymol, has been used as an extractant in automated single-drop microextraction. The extraction procedure was carried out within the 5 mL void of an automatic syringe pump. A 9-position head valve served the aspiration of all required solutions, air, waste disposal, and hyphenation with the HPLC instrument. Sample mixing during extraction was done by a magnetic stirring bar placed inside the syringe. Only 60 μL of NADES were required omitting toxic classical solvents and improving the greenness of the proposed methodology. By direct injection, linear working ranges between 0.1 and 5 μg L were achieved for all fluoroquinolones. The limit of quantification values and enrichment factors ranged from 20 ng L to 30 ng L and 35 to 45, respectively. Accuracies obtained from the analysis of spiked surface water and wastewater treatment plant effluent analysis at two concentration levels (0.5 and 4 μg L) ranged from 84.6% to 119.7%, with RSD values typically <3%.
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http://dx.doi.org/10.1016/j.talanta.2022.123476DOI Listing
August 2022

Sequential Injection Analysis for Automation and Evaluation of Drug Liberation Profiles: Clotrimazole Liberation Monitoring.

Molecules 2021 Sep 12;26(18). Epub 2021 Sep 12.

Department of Analytical Chemistry, Faculty of Pharmacy in Hradec Králové, Charles University, 500 05 Hradec Králové, Czech Republic.

A fully automated sequential injection system was tested in terms of its application in liberation testing, and capabilities and limitations were discussed for clotrimazole liberation from three semisolid formulations. An evaluation based on kinetic profiles obtained in short and longer sampling intervals and steady-state flux values were applied as traditional methods. The obtained clotrimazole liberation profile was faster in the case of Delcore and slower for Clotrimazol AL and Canesten cream commercial formulations. The steady-state flux values for the tested formulations were 52 µg cm h for Canesten, 35 µg cm h for Clotrimazol AL, and 7.2 µg cm h for Delcore measured in 4 min sampling intervals. A simplified approach for the evaluation of the initial rate based on the gradient between the second and third sampling points was used for the first time and was found to correspond well with the results of the conventional methods. A comparison based on the ratio of the steady-state flux and the initial rate values for Canesten and Clotrimazol AL proved the similarity of the obtained results. The proposed alternative was successfully implemented for the comparison of short-term kinetic profiles. Consequently, a faster and simpler approach for dissolution/liberation testing can be used.
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http://dx.doi.org/10.3390/molecules26185538DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8467677PMC
September 2021

Lab-In-Syringe with Bead Injection Coupled Online to High-Performance Liquid Chromatography as Versatile Tool for Determination of Nonsteroidal Anti-Inflammatory Drugs in Surface Waters.

Molecules 2021 Sep 3;26(17). Epub 2021 Sep 3.

Department of Analytical Chemistry, Faculty of Pharmacy in Hradec Králové, Charles University, Akademika Heyrovského 1203, 500 05 Hradec Králové, Czech Republic.

We report on the hyphenation of the modern flow techniques Lab-In-Syringe and Lab-On-Valve for automated sample preparation coupled online with high-performance liquid chromatography. Adopting the bead injection concept on the Lab-On-Valve platform, the on-demand, renewable, solid-phase extraction of five nonsteroidal anti-inflammatory drugs, namely ketoprofen, naproxen, flurbiprofen, diclofenac, and ibuprofen, was carried out as a proof-of-concept. In-syringe mixing of the sample with buffer and standards allowed straightforward pre-load sample modification for the preconcentration of large sample volumes. Packing of ca. 4.4 mg microSPE columns from Oasis HLB sorbent slurry was performed for each sample analysis using a simple microcolumn adapted to the Lab-On-Valve manifold to achieve low backpressure during loading. Eluted analytes were injected into online coupled HPLC with subsequent separation on a Symmetry C18 column in isocratic mode. The optimized method was highly reproducible, with RSD values of 3.2% to 7.6% on 20 µg L level. Linearity was confirmed up to 200 µg L and LOD values were between 0.06 and 1.98 µg L. Recovery factors between 91 and 109% were obtained in the analysis of spiked surface water samples.
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http://dx.doi.org/10.3390/molecules26175358DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8433787PMC
September 2021

Inhibition of AKR1B10-mediated metabolism of daunorubicin as a novel off-target effect for the Bcr-Abl tyrosine kinase inhibitor dasatinib.

Biochem Pharmacol 2021 10 30;192:114710. Epub 2021 Jul 30.

Department of Biochemical Sciences, Faculty of Pharmacy, Charles University, Akademika Heyrovskeho 1203, 50005 Hradec Kralove, Czech Republic. Electronic address:

Bcr-Abl tyrosine kinase inhibitors significantly improved Philadelphia chromosome-positive leukaemia therapy. Apart from Bcr-Abl kinase, imatinib, dasatinib, nilotinib, bosutinib and ponatinib are known to have additional off-target effects that might contribute to their antitumoural activities. In our study, we identified aldo-keto reductase 1B10 (AKR1B10) as a novel target for dasatinib. The enzyme AKR1B10 is upregulated in several cancers and influences the metabolism of chemotherapy drugs, including anthracyclines. AKR1B10 reduces anthracyclines to alcohol metabolites that show less antineoplastic properties and tend to accumulate in cardiac tissue. In our experiments, clinically achievable concentrations of dasatinib selectively inhibited AKR1B10 both in experiments with recombinant enzyme (Ki = 0.6 µM) and in a cellular model (IC = 0.5 µM). Subsequently, the ability of dasatinib to attenuate AKR1B10-mediated daunorubicin (Daun) resistance was determined in AKR1B10-overexpressing cells. We have demonstrated that dasatinib can synergize with Daun in human cancer cells and enhance its therapeutic effectiveness. Taken together, our results provide new information on how dasatinib may act beyond targeting Bcr-Abl kinase, which may help to design new chemotherapy regimens, including those with anthracyclines.
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http://dx.doi.org/10.1016/j.bcp.2021.114710DOI Listing
October 2021

The role of pKa, log P of analytes, and protein matrix in solid-phase extraction using native and coated nanofibrous and microfibrous polymers prepared via meltblowing and combined meltblowing/electrospinning technologies.

Talanta 2021 Sep 30;232:122470. Epub 2021 Apr 30.

Charles University, Faculty of Pharmacy in Hradec Králové, Department of Analytical Chemistry, Akademika Heyrovského 1203, 50005, Hradec Králové, Czech Republic. Electronic address:

Effect of physicochemical properties including dissociation constant (pKa) and partition coefficient (log P) of the compounds on their extraction efficiency in sample preparation using fibrous polymer sorbents has been demonstrated. Poly-ε-caprolactone as meltblown/electrospun composite fibers, and polypropylene, polyethylene, poly(3-hydroxybutyrate), poly(lactic acid), and polyamide 6 in the meltblown fiber format were used as sorbents in solid-phase extraction. In addition, the polycaprolactone fibers were coated with dopamine, dopamine combined with heparin, and tannin, respectively, to modify their extraction properties. These fibers that were not yet used for extractions and the unique combination of sorbents and analytes significantly extends the scope of nanofibrous extraction. The extraction efficiency was determined using model pharmaceuticals including acetylsalicylic acid, moxonidine, metoprolol, propranolol, propafenone, diltiazem, atorvastatin, and amiodarone. These model compounds displayed the widest differences in both pKa and log P values. The extraction efficiency of some of the fibers reached 96.64%. Coating of polycaprolactone fibers with dopamine significantly improved extraction efficiency of slightly retained metoprolol while moxonidine was not retained on any sorbent. The fibrous sorbents were also tested for extraction of pharmaceuticals in bovine serum albumin and human serum, respectively, to demonstrate their capability to extract them from a complex protein-containing matrix. The clean-up efficiency of our fibers was compared with that of a commercial restricted access media (RAM) C-18 alkyl-diol silica column. Our technique is in accordance with the requirements of modern sample preparation techniques.
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http://dx.doi.org/10.1016/j.talanta.2021.122470DOI Listing
September 2021

3D printed permeation module to monitor interaction of cell membrane transporters with exogenic compounds in real-time.

Anal Chim Acta 2021 Apr 7;1153:338296. Epub 2021 Feb 7.

Department of Analytical Chemistry, Faculty of Pharmacy in Hradec Králové, Charles University, Akademika Heyrovského 1203, 500 05, Hradec Králové, Czech Republic.

A new design of permeation module based on 3D printing was developed to monitor the interaction of exogenic compounds with cell membrane transporters in real-time. The fluorescent marker Rhodamine 123 (Rho123) was applied as a substrate to study the activity of the P-glycoprotein membrane transporter using the MDCKII-MDR1 genetically modified cell line. In addition, the inhibitory effect of verapamil (Ver), a prototype P-glycoprotein inhibitor, was examined in the module, demonstrating an enhanced Rho123 transfer and accumulation into cells as well as the applicability of the module for P-glycoprotein inhibitor testing. Inhibition was demonstrated for different ratios of Rho123 and Ver, and their competition in terms of interaction with the P-glycoprotein transporter was monitored in real-time. Employing the 3D-printed module, permeation testing was shortened from 8 h in the conventional module to 2 h and evaluation based on kinetic profiles in every 10 min was possible in both donor and acceptor compartments. We also show that monitoring Rho123 levels in both compartments enables calculate the amount of Rho123 accumulated inside cells without the need of cell lysis.
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http://dx.doi.org/10.1016/j.aca.2021.338296DOI Listing
April 2021

Determination of Ochratoxin A and Ochratoxin B in Archived Tokaj Wines (Vintage 1959-2017) Using On-Line Solid Phase Extraction Coupled to Liquid Chromatography.

Toxins (Basel) 2020 11 24;12(12). Epub 2020 Nov 24.

The Department of Analytical Chemistry, Faculty of Pharmacy in Hradec Králové, Charles University, Ak. Heyrovského 1203, 500 05 Hradec Králové, Czech Republic.

According to the EU legislation, ochratoxin A contamination is controlled in wines. Tokaj wine is a special type of sweet wine produced from botrytized grapes infected by "noble rot" . Although a high contamination was reported in sweet wines and noble rot grapes could be susceptible to coinfection with other fungi, including ochratoxigenic species, no screening of Tokaj wines for mycotoxin contamination has been carried out so far. Therefore, we developed an analytical method for the determination of ochratoxin A (OTA) and ochratoxin B (OTB) involving online SPE coupled to HPLC-FD using column switching to achieve the fast and sensitive control of mycotoxin contamination. The method was validated with recoveries ranging from 91.6% to 99.1% with an RSD less than 2%. The limits of quantification were 0.1 and 0.2 µg L for OTA and OTB, respectively. The total analysis time of the online SPE-HPLC-FD method was a mere 6 min. This high throughput enables routine analysis. Finally, we carried out an extensive investigation of the ochratoxin contamination in 59 Slovak Tokaj wines of 1959-2017 vintage. Only a few positives were detected. The OTA content in most of the checked wines did not exceed the EU maximum tolerable limit of 2 µg L, indicating a good quality of winegrowing and storing.
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http://dx.doi.org/10.3390/toxins12120739DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7761308PMC
November 2020

Lab-In-Syringe for automated double-stage sample preparation by coupling salting out liquid-liquid extraction with online solid-phase extraction and liquid chromatographic separation for sulfonamide antibiotics from urine.

Talanta 2021 Jan 23;221:121427. Epub 2020 Jul 23.

Charles University, Faculty of Pharmacy in Hradec Králové, Department of Analytical Chemistry, Akademika Heyrovského 1203, 500 05, Hradec Králové, Czech Republic.

A double-stage Lab-In-Syringe automated extraction procedure coupled online to HPLC for the determination of four sulfonamides in urine has been developed. Our method is based on homogeneous liquid-liquid extraction at pH 3 using water-miscible acetonitrile with induction of phase separation by the addition of a saturated solution of kosmotropic salts MgSO and NaCl. The procedure allowed extraction of the moderately polar model analytes and the use of a solvent that is compatible with the used separation technique. The automated sample preparation system based on the stirring-assisted Lab-In-Syringe approach was coupled on-line with HPLC-UV for the subsequent separation of the sulfonamide antibiotics. To improve both preconcentration factor and extract cleanup, the analytes were trapped at pH 10 in an anion-exchange resin cartridge integrated into the HPLC injection loop thus achieving a double-stage sample clean-up. Analytes were eluted using an acidic HPLC mobile phase in gradient elution mode. Running the analytes separation and the two-step preparation of the following sample in parallel reduced the total time of analysis to mere 13.5 min. Limits of detection ranged from 5.0 to 7.5 μg/L with linear working ranges of 50-5000 μg/L (r > 0.9997) and RSD ≤ 5% (n = 6) at a concentration level of 50 μg/L. Average recovery values were 102.7 ± 7.4% after spiking of urine with sulfonamides at concentrations of 2.5 and 5 mg/L followed by 5 times dilution. To the best of our knowledge, the use of Lab-In-Syringe for the automation of coupled homogeneous liquid-liquid extraction and SPE for preparation of the complex matrices suitable for separation techniques is here presented for the first time.
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http://dx.doi.org/10.1016/j.talanta.2020.121427DOI Listing
January 2021

On-line polydopamine coating as a new way to functionalize polypropylene fiber sorbent for solid phase extraction.

Talanta 2020 Nov 29;219:121189. Epub 2020 May 29.

Charles University, Faculty of Pharmacy, The Department of Analytical Chemistry, Ak. Heyrovského 1203, 500 05, Hradec Králové, Czech Republic.

Effective process, including a cartridge packing polypropylene fiber sorbent modified by following on-line polydopamine coating, for on-line solid phase extraction in 2D UHPLC system has been developed. Hydrophobic surface of mechanically stable polypropylene fibers was hydrophilized using an automated and reproducible in situ coating process to enable good wettability and effective extraction of polar compounds. Polymerization mixture consisting dopamine and TRIS buffer was circulated through the cartridge containing polypropylene fibers using a peristaltic pump to achieve polymerization. This process was optimized in terms of dopamine amount in the polymerization mixture, its flow rate, and polymerization time. Best results were obtained with 25 mL polymerization mixture containing 20 mg dopamine circulated through the cartridge at a flow rate of 2.07 mL min for 60 min. Prepared cartridges were evaluated via measurement of the recovery and reproducibility using chlorogenic acid as a model compound. Overall reproducibility of our multistep process including eight cartridges in 2D UHPLC system, each measured in triplicate, was 3.61% (n = 24).
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http://dx.doi.org/10.1016/j.talanta.2020.121189DOI Listing
November 2020

Doping Polysulfone Membrane with Alpha-Tocopherol and Alpha-Lipoic Acid for Suppressing Oxidative Stress Induced by Hemodialysis Treatment.

Macromol Biosci 2020 07 15;20(7):e2000046. Epub 2020 Jun 15.

LAQV-REQUIMTE, Department of Chemical Sciences, Faculty of Pharmacy, University of Porto, Rua de Jorge Viterbo Ferreira 228, Porto, 4050-313, Portugal.

The reduction of free radicals by bioactive membranes used for hemodialysis treatment is an important topic due to the constant rise of oxidative stress-associated cardiovascular mortality by hemodialysis patients. Therefore, it is urgent to find an effective solution that helps to solve this problem. Polysulfone membranes enriched with α-lipoic acid, α-tocopherol, and with both components are fabricated by spin coating. The antioxidant properties of these membranes are evaluated in vitro by determining the lipid-peroxidation level and the total antioxidant status of the blood plasma. The biocompatibility is assessed by quantifying the protein adsorption, platelet adhesion, complement activation, and hemolytic effect. All types of membranes show in vitro antioxidant activity and a trend to reduce oxidative stress in vivo; the best results show membranes prepared with a combination of both compounds and prove to be nonhemolytic and hemocompatible. Moreover, the membrane specific separation ability for the main waste products is not affected by antioxidants incorporation.
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http://dx.doi.org/10.1002/mabi.202000046DOI Listing
July 2020

Nanofibers as advanced sorbents for on-line solid phase extraction in liquid chromatography: A tutorial.

Anal Chim Acta 2020 Jul 22;1121:83-96. Epub 2020 Apr 22.

Charles University, Faculty of Pharmacy, The Department of Analytical Chemistry, Ak. Heyrovského 1203, 500 05, Hradec Králové, Czech Republic. Electronic address:

Polymers in nanofiber format promise a great potential as sorbents for extraction techniques. This tutorial provides an overview of direct coupling of extraction techniques based on nanofibers to liquid chromatography. Arrangements of the fibers in conventional extraction cartridges are demonstrated. Selection of suitable nanomaterials according to their surface density, wettability, and mechanical stability is proposed and personal experience of the authors commented. Optimization of on-line extraction procedure, practical aspects, technical problems, pitfalls, pros, and cons of using nanofibers for extraction in high-pressure chromatography systems are also discussed and several examples presented. The following text comprehensively summarizes numerous reports that dealt with the topic. Future perspectives of advanced nanofiber materials and approaches that concern polymer fibers modifications are also included.
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http://dx.doi.org/10.1016/j.aca.2020.04.045DOI Listing
July 2020

Poly-ε-caprolactone Nanofibrous Polymers: A Simple Alternative to Restricted Access Media for Extraction of Small Molecules from Biological Matrixes.

Anal Chem 2020 05 30;92(10):6801-6805. Epub 2020 Apr 30.

Faculty of Pharmacy, Department of Analytical Chemistry, Charles University, 50005 Hradec Králové, Czech Republic.

Poly-ε-caprolactone nanofibrous polymer has been used as an alternative to restricted access media for extraction of protein-containing biological samples and direct transfer in the chromatographic system. Three commercial cartridges differing in length and internal diameter have been manually packed with the composite material prepared from poly-ε-caprolactone nanofibers coated on poly-ε-caprolactone microfibrous scaffold and connected to the column-switching chromatographic system. Bovine milk and human serum (25 μL) spiked with a mixture of methyl-, ethyl-, propyl-, and butylparaben in a concentration range of 1-100 μg mL were online extracted using the cartridge-containing fibers. Then, 5 and 20% (v/v) aqueous methanol was applied as the washing mobile phase. While the ballast protein macromolecules were quantitatively eluted from the nano/microfibrous composite sorbent, the parabens were retained. After the mobile phase was switched to a stronger one, these compounds were then eluted from the extraction sorbent, directed in the analytical column, and finally separated. An extraction efficiency of 86-101% for all parabens achieved using the optimum-sized cartridge and a repeatability of the extraction procedure of 0.06-1.95% RSD were obtained.
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http://dx.doi.org/10.1021/acs.analchem.0c00544DOI Listing
May 2020

The Automation Technique Lab-In-Syringe: A Practical Guide.

Molecules 2020 Apr 1;25(7). Epub 2020 Apr 1.

Department of Analytical Chemistry, Charles University, Faculty of Pharmacy, Akademika Heyrovského 1203, 500 05 Hradec Králové, Czech Republic.

About eight years ago, a new automation approach and flow technique called "Lab-In-Syringe" was proposed. It was derived from previous flow techniques, all based on handling reagent and sample solutions in a flow manifold. To date Lab-In-Syringe has evidently gained the interest of researchers in many countries, with new modifications, operation modes, and technical improvements still popping up. It has proven to be a versatile tool for the automation of sample preparation, particularly, liquid-phase microextraction approaches. This article aims to assist newcomers to this technique in system planning and setup by overviewing the different options for configurations, limitations, and feasible operations. This includes syringe orientation, in-syringe stirring modes, in-syringe detection, additional inlets, and addable features. The authors give also a chronological overview of technical milestones and a critical explanation on the potentials and shortcomings of this technique, calculations of characteristics, and tips and tricks on method development. Moreover, a comprehensive overview of the different operation modes of Lab-In-Syringe automated sample pretreatment is given focusing on the technical aspects and challenges of the related operations. We further deal with possibilities on how to fabricate required or useful system components, in particular by 3D printing technology, with over 20 different elements exemplarily shown. Finally, a short discussion on shortcomings and required improvements is given.
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http://dx.doi.org/10.3390/molecules25071612DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7181287PMC
April 2020

Development of novel liquid chromatography method for clinical monitoring of vitamin B metabolites and B status in the whole blood.

Talanta 2020 May 2;211:120702. Epub 2020 Jan 2.

The Department of Analytical Chemistry, Faculty of Pharmacy, Charles University, Akademika Heyrovského, 1203, Hradec Králové, 500 05, Czech Republic.

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http://dx.doi.org/10.1016/j.talanta.2019.120702DOI Listing
May 2020

3D-Printed Magnetic Stirring Cages for Semidispersive Extraction of Bisphenols from Water Using Polymer Micro- and Nanofibers.

Anal Chem 2020 03 13;92(5):3964-3971. Epub 2020 Feb 13.

Department of Analytical Chemistry, Faculty of Pharmacy in Hradec Králové, Charles University, Akademika Heyrovského 1203, Hradec Králové 50 005, Czech Republic.

A magnetic stirring device allowing semidispersive solid phase extraction of eight bisphenols (A, AF, AP, C, BP, G, M, and Z) from river waters using polymer nano- and microfibers followed by HPLC with spectrophotometric detection has been developed and applied. About 50 mg of fibers was placed in a round, cage-like housing consisting of two identical 3D printed pieces that were locked together by a magnetic stirring bar. Magnetic stirring action of the cage devices enabled highly efficient interaction of the fibers housed inside with the aqueous samples and analyte transfer without risking fiber compaction and/or damaging. Polypropylene was found to be the best-suited filament material for the cage 3D printing, and polycaprolactone fibers appeared the most efficient sorbent out of eight tested polymers. Experimental design revealed that analytes extraction from 100 mL aqueous samples was completed within 50 min and stripping in methanol required less than 35 min. Cage housing enabled simple and robust handling of the fibrous sorbent that could be used repeatedly up to at least 5 times. Procedural repeatability was less than 5% RSD, and limits of detection and quantitation were 0.1-2.1 and 0.4-7.0 μg L, respectively. Analyte recoveries at 50 μg L level ranged from 87.1% to 106.5% in the analysis of two spiked river and two lake waters.
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http://dx.doi.org/10.1021/acs.analchem.9b05455DOI Listing
March 2020

Polycaprolactone nanofibers functionalized with a dopamine coating for on-line solid phase extraction of bisphenols, betablockers, nonsteroidal drugs, and phenolic acids.

Mikrochim Acta 2019 10 24;186(11):710. Epub 2019 Oct 24.

The Department of Analytical Chemistry, Faculty of Pharmacy, Charles University, Ak. Heyrovského 1203, 500 05, Hradec Králové, Czech Republic.

Polycaprolactone composite nanofibers coated with a polydopamine layer are introduced as a new type of absorption material for on-line solid phase extraction (SPE) in chromatographic system. A hybrid technology combining the electrospinning and melt blowing was used for the preparation of 3D-structured microfiber/nanofibrous polycaprolactone composite. The dopamine coating was then applied to functionalize the micro/nanofibers. Polydopamine-coated polycaprolactone fibers were tested as an extraction phase in on-line SPE prior to HPLC separation and UV detection. Four groups of biologically active substances including bisphenols (Bisphenol S, Bisphenol AF, Bisphenol A, Bisphenol C, Bisphenol AP, Bisphenol Z, Bisphenol BP, and Bisphenol M), betablockers (Timolol, Metoprolol, Labetalol, and Propranolol), nonsteroidal antiphlogistic drugs (Salicylic acid, Ketoprofen, Naproxen, Indomethacin, Diclofenac, Ibuprophen, and Meclofenamic acid), and phenolic acids (Chlorogenic acid, Caffeic acid, Sinapic acid, m-Coumaric acid, Benzoic acid, and Cinnamic acid) were used as the model analytes. Neat and coated fibers were compared and applied as sorbents for the on-line extraction set-up. Both materials produced good extraction potential for the determination of bisphenols and nonsteroidal drugs in model biological and environmental samples including river water, human urine, and blood serum. However, the polydopamine layer significantly increased the extraction efficiency of polar drugs. Typical repeatability of on-line extraction procedure on polydopamine coated fibers was in the range 0.12-4.11% for bisphenols, 0.55-1.41% for antiphlogistic drugs, 0.59-2.52% for phenolic acids, and 1.01-1.65% for betablockers. Graphical abstract Schematic representation of polycaprolactone composite nanofibers coated with a polydopamine layer as an advanced absorption material for on-line solid phase extraction in chromatography.
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http://dx.doi.org/10.1007/s00604-019-3846-2DOI Listing
October 2019

Novel nanofibrous sorbents for the extraction and determination of resveratrol in wine.

Talanta 2020 Jan 26;206:120181. Epub 2019 Jul 26.

Charles University, Faculty of Pharmacy, The Department of Analytical Chemistry, Ak. Heyrovského 1203, 500 05, Hradec Králové, Czech Republic. Electronic address:

On-line SPE HPLC method using nanofibrous sorbents for the extraction and determination of resveratrol in wine was developed and validated. Different types of nanofibrous and microfibrous polymers were tested and compared with commercial monolithic C18 sorbent. Polyamide and polyacrylonitrile nanofibers and composite materials composed of respective polycaprolactone and poly(vinylidene difluoride) nanofibers at microfibrous scaffold were included among tested materials. Two different polycaprolactone-based materials were prepared and their effect on the extraction properties studied. Alternatively, dopamine-coated polycaprolactone fibers were also used. Poly(vinylidene difluoride) nanofibers/polycaprolactone microfibers composite was found as the most effective sorbent and utilized for the method validation. Resveratrol in red wine was determined using our validated on-line SPE HPLC method.
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http://dx.doi.org/10.1016/j.talanta.2019.120181DOI Listing
January 2020

New generation of sequential injection chromatography: Great enhancement of capabilities of separation using flow analysis.

Talanta 2019 Nov 4;204:272-277. Epub 2019 Jun 4.

Department of Analytical Chemistry, Charles University, Faculty of Pharmacy in Hradec Králové, Akademika Heyrovského 1203/8, 500 05, Hradec Králové, Czech Republic.

Since its inception, sequential injection chromatography (SIC) has evolved through several stages. Key moments including introduction of the novel technique combining sequential injection analysis and monolithic column, the first generation of commercial SIC system employing robust pump, the utilization of columns packed with fused-core particles, the on-line hyphenation of extraction and separation steps in SIC, are now followed by the second generation of commercial SIC system employing stainless steel syringe pump and parts optimized for chromatographic separation. The key developments always mean acceleration of the evolution by opening new avenues and reduction of compromises in automated analytical methods based on the flow analysis. The updates, new features, and prospects of the novel instrument are described and discussed on perspective of the method developed for extraction and separation of selected phenolic acids (gallic, protocatechuic, caffeic, p-coumaric and ferulic). The method hyphenates miniaturized on-line solid phase extraction using strong anion exchange sorbent in commercial cartridge for HPLC (20 × 1 mm) and liquid chromatography using chromatographic column (C18 50 × 4.6 mm, 5 μm particles) packed with fused-core particles in the SIC manifold. The separation in gradient mode used acetonitrile: aqueous formic acid pH 2.0 mobile phase and spectrophotometric detection at 270, 300, and 320 nm. Injected sample volumes were 200 and 500 μL. The performance of the extraction step was characterized by the recovery 94.0-107.8%, enrichment factors about 20 or 50, and the separation by peak capacities 13-34, peak symmetries 1.17-1.64, and resolutions 0.82-3.75). While using a sample volume of 200 μL, our method was characterized by the following validation parameters: LODs of 0.0075-0.03 mg L, LOQs of 0.025-0.10 mg L, calibration ranges 0.025-2.50 mg L (r > 0.999), repeatability of signal at 0.50 mg Lof RSD ≤ 1.46% (n = 6), and overall time of analysis 7.1 min. The results including pilot analysis of white and red wines demonstrated the capability of novel SIC instrument to enable fast, selective, and sensitive analysis.
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http://dx.doi.org/10.1016/j.talanta.2019.05.108DOI Listing
November 2019

Furosemide ethanol-free oral solutions for paediatric use: formulation, HPLC method and stability study.

Eur J Hosp Pharm 2018 May 2;25(3):144-149. Epub 2017 Aug 2.

Department of Analytical Chemistry, Charles University, Hradec Kralove, Czech Republic.

Background: Oral liquid solutions of the diuretic active ingredient furosemide (FUR) marketed across Europe do not comply with recent requirements for paediatric preparation owing to their ethanol content and, moreover, in some countries only tablet or injection dosage forms of furosemide are available.

Objectives: To formulate extemporaneous paediatric ethanol-free solutions of FUR (2 mg/mL) with suitable solubility in the aqueous vehicle and an acceptable taste and to evaluate their stability under two different storage conditions during a 9-month study period.

Methods: Our work presents two developed formulations of FUR ethanol-free paediatric oral solutions 2 mg/mL for easy extemporaneous compounding in a pharmacy. FUR solubility avoiding the use of ethanol was achieved using sodium hydroxide (formulation F1) or disodium hydrogen phosphate dodecahydrate (formulation F2). The preparations were stored at 25°C±3°C or at 40°C±0.5°C and protected from light. For FUR and preservative, methylparaben (MP), a stability assay was conducted by a high-performance liquid chromatography validated method and determination of pH stability.

Results: The remaining FUR concentration was >90% of the initial concentration after 270 days in both formulations at both storage conditions, 25°C and 40°C. The concentration of MP decreased significantly in the formulation F2 stored at 40°C.

Conclusions: Both formulations were stable when stored at room temperature for up to 9 months; formulation F1 was stable even at 40°C. MP used as an antimicrobial agent fully satisfied the recommended criteria for preservative efficacy in oral preparations according to the European Pharmacopoeia 9.0 (5.1.3).
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http://dx.doi.org/10.1136/ejhpharm-2017-001264DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6452408PMC
May 2018

Preparation of citrinin-selective molecularly imprinted polymer and its use for on-line solid-phase extraction coupled to liquid chromatography.

Anal Bioanal Chem 2019 Apr 19;411(11):2395-2404. Epub 2019 Feb 19.

The Department of Analytical Chemistry, Faculty of Pharmacy, Charles University, Heyrovského 1203, 500 05, Hradec Králové, Czech Republic.

A new selective molecularly imprinted polymer has been prepared and used for extraction in on-line SPE-HPLC to achieve the selective determination of citrinin. Four different imprinted polymers varying in combinations of components were prepared by bulk polymerization and evaluated in terms of binding capacity and selectivity. Imprinted polymer prepared from a mixture comprising 1-hydoxy-2-naphtoic acid as the template molecule, acrylamide as the structural monomer, ethylene dimethacrylate as the cross-linker (in a molar ratio of 1:4:16), and acetonitrile as the porogenic solvent exhibited the best properties. The selectivity of this sorbent was confirmed by comparison with the non-imprinted counterpart prepared using the same polymerization carried out in the absence of template. Imprinted polymer was packed in a 20 × 3 mm i.d. steel cartridge and coupled to the on-line SPE-HPLC system through a six-port switching valve. The method for determination of citrinin including the on-line extraction step was then developed and validated. The sample in the form of methanolic extract was loaded, cleaned, and preconcentrated in the imprinted SPE cartridge. Subsequent separation of citrinin from residual interferences was achieved using the analytical column Kinetex Biphenyl 100 × 4.6 mm i.d., 5 μm particle size, and fluorescence detection (Ex 335, Em 500 nm). The total analysis time was only 9.50 min. Our fully validated method was also applied to analysis of food supplements based on red yeast rice extracts, the control of which is implemented in European legislation. Only minor yet acceptable contamination was found in tested samples.
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http://dx.doi.org/10.1007/s00216-019-01682-9DOI Listing
April 2019

Screening of extraction properties of nanofibers in a sequential injection analysis system using a 3D printed device.

Talanta 2019 May 14;197:517-521. Epub 2019 Jan 14.

Department of Analytical Chemistry, Faculty of Pharmacy in Hradec Králové, Charles University, Heyrovského, 1203, Hradec Králové 50 005, Czech Republic.

A novel application of the three-dimensional printing technology for the automation of solid phase extraction procedures in a low-pressure sequential injection analysis system is presented. A 3D printed device was used as a housing for nanofiber membranes in solid phase extraction. The applicability of the device is demonstrated with the extraction of substances of various physical-chemical properties. Pharmaceuticals including non-steroidal anti-inflammatory drugs, antihistaminics, and steroidal structures, as well as emerging pollutants such as bisphenols and pesticide metsulfuron methyl were used as model analytes to study the extraction performance of the nanofibers. Six different nanofiber types comprising polyamide, polyethylene, polyvinylidene fluoride, polycaprolactone combined with polyvinylidene fluoride, and polyacrylonitrile, produced by electrospinning were tested in solid phase extraction. The suitability of specific nanofibers for particular analytes is demonstrated.
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http://dx.doi.org/10.1016/j.talanta.2019.01.050DOI Listing
May 2019

A Comparative Study of Advanced Stationary Phases for Fast Liquid Chromatography Separation of Synthetic Food Colorants.

Molecules 2018 Dec 15;23(12). Epub 2018 Dec 15.

Department of Analytical Chemistry, Faculty of Pharmacy in Hradec Králové, Charles University, Heyrovského 1203, Hradec Králové 50005, Czech Republic.

Food analysis demands fast methods for routine control and high throughput of samples. Chromatographic separation enables simultaneous determination of numerous compounds in complex matrices, several approaches increasing separation efficiency and speed of analysis were involved. In this work, modern types of column with monolithic rod or superficially porous particles were employed and compared for determination of eight synthetic food dyes, their chromatographic performance was evaluated. During method optimization, cyano stationary phase Chromolith Performance CN 100 × 4.6 mm and Ascentis Express ES-CN 100 × 4.6 mm, 5 µm were selected for the separation of polar colorants. The separation was performed by gradient elution of acetonitrile/methanol and 2% water solution of ammonium acetate at flow rate 2.0 mL min. Mobile phase composition and the gradients were optimized in order to enable efficient separation on both columns. The method using fused-core particle column provided higher separation efficiency, narrow peaks of analytes resulted in increased peak capacity and shortening of analysis time. After the validation, the method was applied for analysis of coloured beers, soft drinks and candies.
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http://dx.doi.org/10.3390/molecules23123335DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6321072PMC
December 2018

Current trends in the analysis and quality control of food supplements based on plant extracts.

Anal Chim Acta 2018 Dec 7;1036:1-15. Epub 2018 Aug 7.

The Department of Analytical Chemistry, Faculty of Pharmacy, Charles University, Akademika Heyrovského 1203, Hradec Králové 500 05, Czech Republic.

Food (dietary) supplements include a wide range of products that are designed to be taken because of their added nutrients and presumed health benefits. Global food supplement sales are experiencing rapid growth and supplements that based on botanicals are among the most popular. The meteoric rise in sales coupled with the general lack of a commitment to pass effective regulation make this market more vulnerable to dishonest producers, increase the likelihood that supplements containing adulterants are sold on the market, and a greater prevalence of safety and quality issues (contamination by pesticides and mycotoxins). In this paper, we present an overview of various sample preparation and analytical techniques that can be used for the determination of bioactive substances in food supplements based on plant extracts and for making purity assessments of plant extracts in these preparations. The analysis looks at data collected from 2012 to 2017. The work is divided according to the different approaches taken when analysing food supplements and groups of bioactive substances found in plant extracts (purity assessments and the determination of bioactive substances).
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http://dx.doi.org/10.1016/j.aca.2018.08.017DOI Listing
December 2018

Where are modern flow techniques heading to?

Anal Bioanal Chem 2018 Oct 6;410(25):6361-6370. Epub 2018 Aug 6.

Department of Analytical Chemistry, Faculty of Pharmacy in Hradec Králové, Charles University, Akademika Heyrovského 1203, 500 05, Hradec Králové, Czech Republic.

This article aims to provide an overview on the transition from earlier laboratory automation using analytical flow approaches toward today's applications of flow methodologies, recent developments, and future trends. The article is directed to flow practitioners while serving as a valuable reference to newcomers in the field in providing insight into flow techniques and conceptual differences in operation across the distinct flow generations. In the focus are the recently developed and complementary techniques Lab-On-Valve and Lab-In-Syringe. In the following, a brief comparison of the different application niches and contributions of flow techniques to past and modern analytical chemistry is given, including (i) the development of sample pretreatment approaches, (ii) the potential applicability for in-situ/on-site monitoring of environmental compartments or technical processes, (iii) the ability of miniaturization of laboratory chemistry, (iv) the unique advantages for implementation of kinetic assays, and finally (v) the beneficial online coupling with scanning or separation analytical techniques. We also give a critical comparison to alternative approaches for automation based on autosamplers and robotic systems. Finally, an outlook on future applications and developments including 3D prototyping and specific needs for further improvements is given. Graphical abstract ᅟ.
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http://dx.doi.org/10.1007/s00216-018-1285-2DOI Listing
October 2018

The biocompatibility and bioactivity of hemodialysis membranes: their impact in end-stage renal disease.

J Artif Organs 2019 Mar 14;22(1):14-28. Epub 2018 Jul 14.

Department of Chemical Sciences, Faculty of Pharmacy, LAQV-REQUIMTE, University of Porto, Rua de Jorge Viterbo Ferreira nº. 228, 450-313, Porto, Portugal.

End-stage renal disease is a growing health problem with increasing prevalence and high health care costs. Patients suffering from end-stage renal disease exhibit higher morbidity and mortality rates compared to the general population. These patients, who are treated using hemodialysis, typically suffer from anemia, inflammation, and oxidative stress. Inadequate dialyzer membrane biocompatibility exacerbates these negative side effects. Modifications of the composition of hemodialysis membranes have improved their biocompatibility and improve the patients' quality of life. Recently, the use of dialyzer membranes coated with bioactive compounds has also been proposed to further ameliorate dialysis-associated problems. Based on a survey of the current literature, application of bioactive membranes decreases the inflammation and oxidative stress of patients treated with hemodialysis.
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http://dx.doi.org/10.1007/s10047-018-1059-9DOI Listing
March 2019

A comparison study of nanofiber, microfiber, and new composite nano/microfiber polymers used as sorbents for on-line solid phase extraction in chromatography system.

Anal Chim Acta 2018 Sep 21;1023:44-52. Epub 2018 Apr 21.

Charles University, Faculty of Pharmacy, The Department of Analytical Chemistry, Ak.Heyrovského 1203, 500 05, Hradec Králové, Czech Republic. Electronic address:

Three different approaches has been used to obtain nano/micro fibers and their diversity and extraction properties were examined. The effect of their structure on stability in an ultra-high-performance liquid chromatography (UHPLC) system during on-line SPE procedure was monitored. Five types of various nano/micro fiber polymers were used as sorbents: polyamide 6 nanofibers, polyvinylidene difluoride nanofibers, polyethylene microfibers, and two new polycaprolactone microfiber/nanofiber and polycaprolactone microfibers/polyvinylidene difluoride nanofibers composite polymers. The fiber polymers were filled in a cartridge directly connected to the UHPLC system and tested. For each polymer, the optimal conditions of the on-line extraction were found and potential applicability on real samples was tested. The determination of ochratoxin A (OTA) in beer matrix was chosen as a case study. Relevant factors such as the mechanical and chemical stability of the nano/microfibers, filling the cartridges, fiber reusability and the possibility and the repeatability of all processes were involved in the proposed study. A new nano/micro composite sorbent consisting of polycaprolactone microfibers/polyvinylidene difluoride nanofibers was chosen as the most suitable sorbent for the on-line extraction of OTA from a beer matrix. The tested validation parameters had the value of intra-day precision lower than 1.48%, linearity in the range from 0.5 to 100 μg L with r ≥ 0.9999 for standard and matrix calibration curve, and recovery in the range 99.1-103.9% at five concentration levels. Long-term precision evaluated for 31 analyses over the period of three months did not exceed 2.9% RSD. It confirmed the column reusability and perfect stability of nano/micro composite sorbent in the presence of organic solvents and after repeated injection of a complex beer matrix.
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http://dx.doi.org/10.1016/j.aca.2018.04.023DOI Listing
September 2018

Lab-In-Syringe automation of stirring-assisted room-temperature headspace extraction coupled online to gas chromatography with flame ionization detection for determination of benzene, toluene, ethylbenzene, and xylenes in surface waters.

J Chromatogr A 2018 Jun 23;1555:1-9. Epub 2018 Apr 23.

Charles University, Faculty of Pharmacy in Hradec Králové, Department of Analytical Chemistry, Akademika Heyrovského 1203, 500 05 Hradec Králové, Czech Republic.

Online coupling of Lab-In-Syringe automated headspace extraction to gas chromatography has been studied. The developed methodology was successfully applied to surface water analysis using benzene, toluene, ethylbenzene, and xylenes as model analytes. The extraction system consisted of an automatic syringe pump with a 5 mL syringe into which all solutions and air for headspace formation were aspirated. The syringe piston featured a longitudinal channel, which allowed connecting the syringe void directly to a gas chromatograph with flame ionization detector via a transfer capillary. Gas injection was achieved via opening a computer-controlled pinch valve and compressing the headspace, upon which separation was initialized. Extractions were performed at room temperature; yet sensitivity comparable to previous work was obtained by high headspace to sample ratio V/V of 1.6:1 and injection of about 77% of the headspace. Assistance by in-syringe magnetic stirring yielded an about threefold increase in extraction efficiency. Interferences were compensated by using chlorobenzene as an internal standard. Syringe cleaning and extraction lasting over 10 min was carried out in parallel to the chromatographic run enabling a time of analysis of <19 min. Excellent peak area repeatabilities with RSD of <4% when omitting and <2% RSD when using internal standard corrections on 100 μg L level were achieved. An average recovery of 97.7% and limit of detection of 1-2 μg L were obtained in analyses of surface water.
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http://dx.doi.org/10.1016/j.chroma.2018.04.055DOI Listing
June 2018

Direct-immersion single-drop microextraction and in-drop stirring microextraction for the determination of nanomolar concentrations of lead using automated Lab-In-Syringe technique.

Talanta 2018 Jul 6;184:162-172. Epub 2018 Mar 6.

Department of Analytical Chemistry, Faculty of Pharmacy in Hradec Králové, Charles University, Akademika Heyrovského 1203, 500 05 Hradec Králové, Czech Republic.

Two operational modes for Lab-In-Syringe automation of direct-immersion single-drop microextraction have been developed and critically compared using lead in drinking water as the model analyte. Dithizone was used in the presence of masking additives as a sensitive chromogenic complexing reagent. The analytical procedure was carried out inside the void of an automatic syringe pump. Normal pump orientation was used to study extraction in a floating drop of a toluene-hexanol mixture. Placing the syringe upside-down allowed the use of a denser-than-water drop of chloroform for the extraction. A magnetic stirring bar was placed inside the syringe for homogenous mixing of the aqueous phase and enabled in-drop stirring in the second configuration while resulting in enhanced extraction efficiency. The use of a syringe as the extraction chamber allowed drop confinement and support by gravitational differences in the syringe inlet. Keeping the stirring rates low, problems related to solvent dispersion such as droplet collection were avoided. With a drop volume of 60 µL, limits of detection of 75 nmol L and 23 nmol L were achieved for the floating drop extraction and the in-drop stirring approaches, respectively. Both methods were characterized by repeatability with RSD typically below 5%, quantitative analyte recoveries, and analyte selectivity achieved by interference masking. Operational differences were critically compared. The proposed methods permitted the routine determination of lead in drinking water to be achieved in less than 6 min.
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http://dx.doi.org/10.1016/j.talanta.2018.02.101DOI Listing
July 2018
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