INTRODUCTION: The analysis of plant and herbal samples is a challenging task for analytical chemists due to the complexity of the matrix combined with the low concentration of analytes. In recent years different liquid-phase microextraction (LPME) techniques coupled with a variety of analytical equipment have been developed for the determination of both organic and inorganic analytes. OBJECTIVE: Over the past few years, the number of research papers in this field has shown a markedly growing tendency. Therefore, the purpose of this review paper is to summarise and critically evaluate research articles focused on the application of LPME techniques for the analysis of plant and herbal samples. RESULTS: Due to the complex nature of the samples, the direct application of LPME techniques to the analysis of plants has not often been done. LPME techniques as well as their modalities have been commonly applied in combination with other pretreatment techniques, including a solid-liquid extraction technique supported by mechanical agitation or auxiliary energies for plant analysis. Applications and the most important parameters are summarised in the tables. CONCLUSION: This review summarises the application of the LPME procedure and shows the major benefits of LPME, such as the low volume of solvents used, high enrichment factor, simplicity of operation and wide selection of applicable detection techniques. We can expect further development of microextraction analytical methods that focus on direct sample analysis with the application of green extraction solvents while fully automating procedures for the analysis of plant materials.

• Klíčová slova
• dispersive liquid-liquid microextraction, herbal, liquid-phase microextraction, plant, single-drop microextraction, solid samples,
• MeSH
• mikroextrakce kapalné fáze * MeSH
• rostliny MeSH
• rozpouštědla MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH
• Názvy látek
• rozpouštědla MeSH

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-1 and 23 nmol L-1 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.

• Klíčová slova
• Automation, Direct-immersion single-drop microextraction, Drinking water, In-drop stirring microextraction, Lab-In-Syringe, Lead, dithizone assay,
• MeSH
• automatizace * MeSH
• injekční stříkačky * MeSH
• magnetické jevy MeSH
• mikroextrakce kapalné fáze * přístrojové vybavení   MeSH
• olovo analýza   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• olovo MeSH

A critical overview on automation of modern liquid phase microextraction (LPME) approaches based on the liquid impregnation of porous sorbents and membranes is presented. It is the continuation of part 1, in which non-dispersive LPME techniques based on the use of the extraction phase (EP) in the form of drop, plug, film, or microflow have been surveyed. Compared to the approaches described in part 1, porous materials provide an improved support for the EP. Simultaneously they allow to enlarge its contact surface and to reduce the risk of loss by incident flow or by components of surrounding matrix. Solvent-impregnated membranes or hollow fibres are further ideally suited for analyte extraction with simultaneous or subsequent back-extraction. Their use can therefore improve the procedure robustness and reproducibility as well as it "opens the door" to the new operation modes and fields of application. However, additional work and time are required for membrane replacement and renewed impregnation. Automation of porous support-based and membrane-based approaches plays an important role in the achievement of better reliability, rapidness, and reproducibility compared to manual assays. Automated renewal of the extraction solvent and coupling of sample pretreatment with the detection instrumentation can be named as examples. The different LPME methodologies using impregnated membranes and porous supports for the extraction phase and the different strategies of their automation, and their analytical applications are comprehensively described and discussed in this part. Finally, an outlook on future demands and perspectives of LPME techniques from both parts as a promising area in the field of sample pretreatment is given.

• Klíčová slova
• Automation, Chromatomembrane, Dynamic liquid phase microextraction, Hollow-fibre liquid phase microextraction, Liquid phase microextraction, Miniaturisation, Static liquid phase microextraction, Supported liquid membrane microextraction,
• MeSH
• automatizace * MeSH
• membrány umělé * MeSH
• mikroextrakce kapalné fáze metody   MeSH
• poréznost MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH
• Názvy látek
• membrány umělé * MeSH

Breast milk analysis provides useful information about acute newborn exposure to harmful substances, such as psychoactive drugs abused by a nursing mother. Since breast milk represents a complex matrix with large amounts of interfering compounds, a comprehensive sample pre-treatment is necessary. This work focuses on determination of amphetamines and synthetic cathinones in human breast milk by microextraction techniques (liquid-phase microextraction and electromembrane extraction), and their comparison to more conventional treatment methods (protein precipitation, liquid-liquid extraction, and salting-out assisted liquid-liquid extraction). The aim of this work was to optimize and validate all the extraction procedures and thoroughly assess their advantages and disadvantages with special regard to their routine clinical use. The applicability of the extractions was further verified by the analysis of six real samples collected from breastfeeding mothers suspected of amphetamine abuse. The membrane microextraction techniques turned out to be the most advantageous as they required low amounts of organic solvents but still provided efficient sample clean-up, excellent quantification limit (0.5 ng mL-1), and good recovery (81-91% and 40-89% for electromembrane extraction and liquid-phase microextraction, respectively). The traditional liquid-liquid extraction as well as the salting-out assisted liquid-liquid extraction showed comparable recoveries (41-85% and 63-88%, respectively), but higher quantification limits (2.5 ng mL-1 and 5 ng mL-1, respectively). Moreover, these methods required multiple operating steps and were time consuming. Protein precipitation was fast and simple, but it demonstrated poor sample clean-up, low recovery (56-58%) and high quantification limit (5 ng mL-1). Based on the overall results, microextraction methods can be considered promising candidates, even for routine laboratory use.

• Klíčová slova
• Amphetamines, Breast milk, Electromembrane extraction, Liquid-phase microextraction, Sample treatment, Synthetic cathinones,
• MeSH
• amfetaminy MeSH
• extrakce kapalina-kapalina MeSH
• lidé MeSH
• limita detekce MeSH
• mateřské mléko * MeSH
• mikroextrakce kapalné fáze * MeSH
• novorozenec MeSH
• rozpouštědla MeSH
• Check Tag
• lidé MeSH
• novorozenec MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• amfetaminy MeSH
• rozpouštědla MeSH

Direct analysis of complex samples is demonstrated by the at-line coupling of hollow fiber liquid-phase microextraction (HF-LPME) to capillary electrophoresis (CE). The hyphenation of the preparative and the analytical technique is achieved through a 3D-printed microextraction device with an HF located in a sample vial of a commercial CE instrument. The internal geometry of the device guides the CE separation capillary into the HF and the CE injection of the HF-LPME extract is performed directly from the HF lumen. The 3D-printing process ensures uniform dimensions of the devices, their constant position inside the sample vial, and excellent repeatability of the HF-LPME as well as the CE injection. The devices are cheap (∼0.01 €) and disposable, thus eliminating any possible sample-carryover, moreover, the at-line CE analysis of the extract is performed fully autonomously with no need for operator's intervention. The developed HF-LPME/CE-UV method is applied to the determination of acidic drugs in dried blood spot and wastewater samples and is characterized by excellent repeatability (RSD, 0.6-9.6%), linearity (r2, 0.9991-0.9999), enrichment (EF, 29-97), sensitivity (LOD, 0.2-3.4 μg/L), and sample throughput (7 samples/h). A further improvement of selected characteristics of the analytical method is achieved by the at-line coupling of HF-LPME to capillary isotachophoresis (ITP) with electrospray ionization-mass spectrometry (ESI-MS). The HF-LPME/ITP-ESI-MS system facilitates enhanced selectivity, matrix-free analytical signals, and up to 34-fold better sensitivity due to the use of ESI-MS detection and additional on-capillary ITP preconcentration of the HF-LPME extracts.

• Klíčová slova
• Acidic drugs, Automation, Capillary electrophoresis, Dried blood spot, Hollow fiber liquid-phase microextraction, Wastewater,
• MeSH
• elektroforéza kapilární MeSH
• hmotnostní spektrometrie s elektrosprejovou ionizací MeSH
• izotachoforéza * MeSH
• léčivé přípravky * MeSH
• mikroextrakce kapalné fáze * MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• léčivé přípravky * MeSH

For the first time, the use of a magnetic stirrer within the syringe of an automated syringe pump and the resulting possible analytical applications are described. A simple instrumentation following roughly the one from sequential injection analyzer systems is used in combination with an adaptor, which is placed onto the barrel of a glass syringe. Swirling around the longitudinal axis of the syringe and holding two strong neodymium magnets, it causes a rotating magnetic field and serves as driver for a magnetic stirring bar placed inside of the syringe. In a first study it was shown that this approach leads to a sealed but also automatically adaptable reaction vessel, the syringe, in which rapid and homogeneous mixing of sample with the required reagents within short time can be carried out. In a second study in-a-syringe magnetic stirring-assisted dispersive liquid-liquid microextraction (MSA-DLLME) was demonstrated by the application of the analyzer system to fluorimetric determination of aluminum in seawater samples using lumogallion. A linear working range up to 1.1 μmol L(-1) and a limit of detection of 6.1 nmol L(-1) were found. An average recovery of 106.0% was achieved for coastal seawaters with a reproducibility of 4.4%. The procedure lasted 210 s including syringe cleaning and only 150 μL of hexanol and 4.1 mL of sample were required.

• Klíčová slova
• Aluminum, In-syringe magnetic stirring-assisted liquid–liquid microextraction, Lumogallion, Seawater, Single-drop extraction,
• MeSH
• časové faktory MeSH
• design vybavení MeSH
• hliník izolace a purifikace   MeSH
• injekční stříkačky MeSH
• limita detekce MeSH
• magnetismus MeSH
• mikroextrakce kapalné fáze přístrojové vybavení   metody   MeSH
• mořská voda analýza   MeSH
• pufry MeSH
• reprodukovatelnost výsledků MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• hliník MeSH
• pufry MeSH

A novel ferrofluid of Fe3O4 nanoparticles and a deep eutectic solvent (DES) composed of menthol and pentanoic acid was introduced as a green microextraction medium. The ferrofluid was successfully used as an extractant for vortex-assisted liquid-liquid microextraction (VALLME) of nonsteroidal anti-inflammatory drugs (NSAIDs) in environmental waters prior to their determination by HPLC-DAD. Once the ferrofluid was dispersed in the sample by vortex agitation, phase separation could be easily achieved by placing a neodymium magnet next to the tube, which eliminated the centrifugation step and simplified the operational procedure. As a result, the sample pretreatment took only ≈2 min. The experimental parameters, including pH, nanoparticle amount, ferrofluid volume, vortex time, salt amount, and disruptive solvent type and its volume, were optimized stepwise. The method showed linear behavior for all NSAIDs from 5 to 100 μg/L, with limit of detection values and enrichment factors in the ranges of 1.68-2.05 μg/L and 38.9-50.6, respectively. Intra- and Inter-day accuracies obtained from the analysis of spiked river, lake, and tap water samples at low and high-quality control levels (20 and 80 μg/L) ranged from 90.3% to 108.0%, with relative standard deviations less than <12.3%. The results of this study demonstrate that the use of DES-based ferrofluid in VALLME can be considered a simple, environmentally friendly, and reliable alternative for the determination of NSAIDs in environmental waters.

• Klíčová slova
• Environmental analysis, Ferrofluid, Green sample preparation, Liquid chromatography, Liquid-phase microextraction, Nonsteroidal anti-inflammatory drugs,
• MeSH
• antiflogistika nesteroidní MeSH
• hluboce eutektická rozpouštědla * MeSH
• koloidy MeSH
• limita detekce MeSH
• mikroextrakce kapalné fáze * metody   MeSH
• rozpouštědla MeSH
• voda MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• antiflogistika nesteroidní MeSH
• hluboce eutektická rozpouštědla * MeSH
• koloidy MeSH
• rozpouštědla MeSH
• voda MeSH

Sample pretreatment techniques or preconcentration constitute a very important step before the analysis of environmental, clinical, pharmaceutical, and other complex samples. Thanks to extraction techniques it is possible to achieve higher method sensitivities and selectivities. Miniaturization microextraction methods make them more environmentally friendly and only small amounts of samples are required. In the past 30 years, a number of microextraction methods have been developed and used and are documented in thousands of articles. Many reviews have been written focusing on their use in specified professional fields or on the latest trends. Unfortunately, no uniform nomenclature has been introduced for these methods. Therefore, this review attempts to classify all the essential microextraction techniques and describes their advantages, disadvantages, and the latest innovations. The methods are divided into two main groups: single drop and sorbent-based techniques according to the type of extraction phase.

• Klíčová slova
• liquid phase microextraction, single drop microextraction, solid phase microextraction,
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

A simple and rapid method for the determination of the methylene blue active substances assay based on in-syringe automation of magnetic stirring-assisted dispersive liquid-liquid microextraction was developed. The proposed method proved to be valid for the determination of anionic surfactant in waste, pond, well, tap, and drinking water samples. Sample mixing with reagents, extraction and phase separation were performed within the syringe of an automated syringe pump containing a magnetic stirring bar for homogenization and solvent dispersion. The syringe module was used upside-down to enable the use of chloroform as an extraction solvent of higher density than water. The calibration was found to be linear up to 0.3mg/L using only 200 µL of solvent and 4 mL of sample. The limits of detection (3σ) and quantification (10σ) were 7.0 µg/L and 22 µg/L, respectively. The relative standard deviation for 10 replicate determinations of 0.1mg/L SBDS was below 3%. Concentrations of anionic surfactants in natural water samples were in the range of 0.032-0.213 mg/L and no significant differences towards the standard method were found. Standard additions gave analyte recoveries between 95% and 106% proving the general applicability and adequateness of the system to MBSA index determination. Compared to the tedious standard method requiring up to 50 mL of chloroform, the entire procedure took only 345 s using 250-times less solvent.

• Klíčová slova
• Anionic surfactants, In-syringe magnetic-stirring-assisted dispersive liquid–liquid microextraction, Methylene blue active substances assay, Sequential injection analysis,
• MeSH
• automatizace * MeSH
• biotest metody   MeSH
• chemické látky znečišťující vodu analýza   MeSH
• injekční stříkačky MeSH
• limita detekce MeSH
• magnetismus * MeSH
• methylenová modř analýza   MeSH
• mikroextrakce kapalné fáze metody   MeSH
• povrchově aktivní látky analýza   MeSH
• rozpouštědla chemie   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• chemické látky znečišťující vodu MeSH
• methylenová modř MeSH
• povrchově aktivní látky MeSH
• rozpouštědla MeSH

Speed and low cost, together with regulatory approval, are the most important requirements of clinical assays. Therefore, a fast and automated on-line sample preparation method is essential for the routine analysis of biological samples. Microextraction by packed sorbent is an option for optimal sample preparation due to its easy automation, minimal requirements for the sample and elution solvent volumes, elimination of evaporation and reconstitution steps, and ability to integrate sample preparation and injection into one step. The use of effective sample preparation steps circumvents the need for chromatographic separation and therefore allows more rapid and less expensive sample analysis in clinical and forensic practice. Two biologically active compounds, amphetamine and methadone, were chosen as representative drugs of abuse for the application of microextraction by packed sorbent coupled directly to mass spectrometry. The developed method was validated, with the results confirming the suitability of the combination of these techniques for the analysis of biological samples. The approach was confirmed to be appropriate for use in clinical and forensic practice with regard to cost and time requirements for analysis.

• Klíčová slova
• Amphetamine, Direct injection, Mass spectrometry, Methadone, Microextraction,
• MeSH
• amfetamin moč   MeSH
• analýza moči přístrojové vybavení   metody   MeSH
• chromatografie kapalinová MeSH
• farmaceutická chemie MeSH
• hmotnostní spektrometrie MeSH
• kalibrace MeSH
• koncentrace vodíkových iontů MeSH
• lidé MeSH
• methadon moč   MeSH
• mikroextrakce kapalné fáze MeSH
• rozpouštědla chemie   MeSH
• soudní lékařství MeSH
• tandemová hmotnostní spektrometrie MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• amfetamin MeSH
• methadon MeSH
• rozpouštědla MeSH