Solid-phase microextraction Arrow combined with comprehensive two-dimensional gas chromatography-mass spectrometry for the elucidation of the volatile composition of honey samples.

In this work, a solid-phase microextraction (SPME) Arrow method combined with comprehensive two-dimensional gas chromatography-mass spectrometry (GC × GC-MS) was developed for the elucidation of the volatile composition of honey samples. The sample preparation protocol was optimized to ensure high extraction efficiency of the volatile organic compounds (VOCs) which are directly associated with the organoleptic properties of honey and its acceptance by the consumers. Following its optimization, SPME Arrow was compared to conventional SPME in terms of sensitivity, precision, and number of extracted VOCs. The utilization of SPME Arrow fibers enabled the determination of 203, 147, and 149 compounds in honeydew honey, flower honey, and pine honey, respectively, while a significantly lower number of compounds (124, 94, and 111 for honeydew honey, flower honey, and pine honey, respectively) was determined using conventional SPME. At the same time, the utilization of SPME Arrow resulted in enhanced sensitivity and precision. All things considered, SPME Arrow and GC × GC-MS can be considered as highly suitable for the elucidation of the volatile composition of complex food samples resulting in high sensitivity and separation efficiency.

Recent advances in the extraction of triazine herbicides from water samples.

Pesticides are excessively used in agriculture to improve the quality of crops by eliminating the negative effects of pests. Among the different groups of pesticides, triazine pesticides are a group of compounds that contain a substituted C3 H3 N3 heterocyclic ring, and they are widely used. Triazine pesticides can be dangerous for humans as well as for the aquatic environment because of their high toxicity and endocrine disrupting effect. However, the concentration of these chemical compounds in water samples is low. Moreover, other compounds that may exist in the water samples can interfere with the determination of triazine pesticides. As a result, it is important to develop sample preparation methods that provide preconcentration of the target analyte and sufficient clean-up of the samples. Recently, a wide variety of novel microextraction and miniaturized extraction techniques (e.g., solid-phase microextraction and liquid-phase microextraction, stir bar sorptive extraction, fabric phase sorptive extraction, dispersive solid-phase extraction, and magnetic solid-phase extraction) have been developed. In this review, we aim to discuss the recent advances regarding the extraction of triazine pesticides from environmental water samples. Emphasis will be given to novel sample preparation methods and novel sorbents developed for sorbent-based extraction techniques.

Multi-Element Analysis Based on an Automated On-Line Microcolumn Separation/Preconcentration System Using a Novel Sol-Gel Thiocyanatopropyl-Functionalized Silica Sorbent Prior to ICP-AES for Environmental Water Samples.

A sol-gel thiocyanatopropyl-functionalized silica sorbent was synthesized and employed for an automated on-line microcolumn preconcentration platform as a front-end to inductively coupled plasma atomic emission spectroscopy (ICP-AES) for the simultaneous determination of Cd(II), Pb(II), Cu(II), Cr(III), Co(II), Ni(II), Zn(II), Mn(II), Hg(II), and V(II). The developed system is based on an easy-to-repack microcolumn construction integrated into a flow injection manifold coupled directly to ICP-AES's nebulizer. After on-line extraction/preconcentration of the target analyte onto the surface of the sorbent, successive elution with 1.0 mol L-1 HNO3 was performed. All main chemical and hydrodynamic factors affecting the effectiveness of the system were thoroughly investigated and optimized. Under optimized experimental conditions, for 60 s preconcentration time, the enhancement factor achieved for the target analytes was between 31 to 53. The limits of detection varied in the range of 0.05 to 0.24 µg L-1, while the limits of quantification ranged from 0.17 to 0.79 µg L-1. The precision of the method was expressed in terms of relative standard deviation (RSD%) and was less than 7.9%. Furthermore, good method accuracy was observed by analyzing three certified reference materials. The proposed method was also successfully employed for the analysis of environmental water samples.

Green Bioanalytical Applications of Graphene Oxide for the Extraction of Small Organic Molecules.

Bioanalysis is the scientific field of the quantitative determination of xenobiotics (e.g., drugs and their metabolites) and biotics (e.g., macromolecules) in biological matrices. The most common samples in bioanalysis include blood (i.e., serum, plasma and whole blood) and urine. However, the analysis of alternative biosamples, such as hair and nails are gaining more and more attention. The main limitations for the determination of small organic compounds in biological samples is their low concentration in these matrices, in combination with the sample complexity. Therefore, a sample preparation/analyte preconcentration step is typically required. Currently, the development of novel microextraction and miniaturized extraction techniques, as well as novel adsorbents for the analysis of biosamples, in compliance with the requirements of Green Analytical Chemistry, is in the forefront of research in analytical chemistry. Graphene oxide (GO) is undoubtedly a powerful adsorbent for sample preparation that has been successfully coupled with a plethora of green extraction techniques. GO is composed of carbon atoms in a sp2 single-atom layer of a hybrid connection, and it exhibits high surface area, as well as good mechanical and thermal stability. In this review, we aim to discuss the applications of GO and functionalized GO derivatives in microextraction and miniaturized extraction techniques for the determination of small organic molecules in biological samples.

Recent Advances in the Extraction of Polycyclic Aromatic Hydrocarbons from Environmental Samples.

Polycyclic aromatic hydrocarbons (PAHs) comprise a group of chemical compounds consisting of two or more fused benzene rings. PAHs exhibit hydrophobicity and low water solubility, while some of their members are toxic substances resistant to degradation. Due to their low levels in environmental matrices, a preconcentration step is usually required for their determination. Nowadays, there is a wide variety of sample preparation techniques, including micro-extraction techniques (e.g., solid-phase microextraction and liquid phase microextraction) and miniaturized extraction techniques (e.g., dispersive solid-phase extraction, magnetic solid-phase extraction, stir bar sorptive extraction, fabric phase sorptive extraction etc.). Compared to the conventional sample preparation techniques, these novel techniques show some benefits, including reduced organic solvent consumption, while they are time and cost efficient. A plethora of adsorbents, such as metal-organic frameworks, carbon-based materials and molecularly imprinted polymers, have been successfully coupled with a wide variety of extraction techniques. This review focuses on the recent advances in the extraction techniques of PAHs from environmental matrices, utilizing novel sample preparation approaches and adsorbents.

Sample Preparation Using Graphene-Oxide-Derived Nanomaterials for the Extraction of Metals.

Graphene oxide is a compound with a form similar to graphene, composed of carbon atoms in a sp2 single-atom layer of a hybrid connection. Due to its significant surface area and its good mechanical and thermal stability, graphene oxide has a plethora of applications in various scientific fields including heterogenous catalysis, gas storage, environmental remediation, etc. In analytical chemistry, graphene oxide has been successfully employed for the extraction and preconcentration of organic compounds, metal ions, and proteins. Since graphene oxide sheets are negatively charged in aqueous solutions, the material and its derivatives are ideal sorbents to bind with metal ions. To date, various graphene oxide nanocomposites have been successfully synthesized and evaluated for the extraction and preconcentration of metal ions from biological, environmental, agricultural, and food samples. In this review article, we aim to discuss the application of graphene oxide and functionalized graphene oxide nanocomposites for the extraction of metal ions prior to their determination via an instrumental analytical technique. Applications of ionic liquids and deep eutectic solvents for the modification of graphene oxide and its functionalized derivatives are also discussed.

Magnetic Solid-Phase Extraction of Organic Compounds Based on Graphene Oxide Nanocomposites.

Graphene oxide (GO) is a chemical compound with a form similar to graphene that consists of one-atom-thick two-dimensional layers of sp2-bonded carbon. Graphene oxide exhibits high hydrophilicity and dispersibility. Thus, it is difficult to be separated from aqueous solutions. Therefore, functionalization with magnetic nanoparticles is performed in order to prepare a magnetic GO nanocomposite that combines the sufficient adsorption capacity of graphene oxide and the convenience of magnetic separation. Moreover, the magnetic material can be further functionalized with different groups to prevent aggregation and extends its potential application. Until today, a plethora of magnetic GO hybrid materials have been synthesized and successfully employed for the magnetic solid-phase extraction of organic compounds from environmental, agricultural, biological, and food samples. The developed GO nanocomposites exhibit satisfactory stability in aqueous solutions, as well as sufficient surface area. Thus, they are considered as an alternative to conventional sorbents by enriching the analytical toolbox for the analysis of trace organic compounds.

Determination of Volatile Compounds in Nut-Based Milk Alternative Beverages by HS-SPME Prior to GC-MS Analysis.

A reliable Headspace-Solid Phase Microextraction (HS-SPME) method was developed for the determination of polar volatile components of commercial nut-based milk alternative drinks prior to Gas Chromatography-Mass Spectrometry (GC-MS) analysis. Under the optimum extraction conditions, a divinylbenzene (DVB)/Carboxen™ CAR)/polydimethylsiloxane (PDMS) fiber was used and 2 mL of sample was heated at 60 °C for 40 min under stirring, without salt addition. Ten compounds from different chemical classes (heptane, a-pinene, toluene, 2-methylpyrazine, 3-heptanone, heptanal, 2-octanone, 1-heptanol, benzaldehyde and 1-octanol) were chosen as model analytes for quantification. Limits of detection and limits of quantification were found to be 0.33-1.67 ng g-1 and 1-5 ng g-1, accordingly. Good linearity, precision and accuracy were obtained as well as a wide linear range. The proposed method was successfully applied to various beverages including almond milk, walnut milk, peanut milk and almond chocolate milk. More than 70 volatile compounds were detected in the different samples. Most of the detected volatiles were aldehydes, ketones and alcohols. This technique can be used for the determination of volatile compounds in nut-based beverages, to detect compositional changes during storage and technological treatment used for their production.

Extraction of Metal Ions with Metal-Organic Frameworks.

Metal-organic frameworks (MOFs) are crystalline porous materials composed of metal ions or clusters coordinated with organic linkers. Due to their extraordinary properties such as high porosity with homogeneous and tunable in size pores/cages, as well as high thermal and chemical stability, MOFs have gained attention in diverse analytical applications. MOFs have been coupled with a wide variety of extraction techniques including solid-phase extraction (SPE), dispersive solid-phase extraction (d-SPE), and magnetic solid-phase extraction (MSPE) for the extraction and preconcentration of metal ions from complex matrices. The low concentration levels of metal ions in real samples including food samples, environmental samples, and biological samples, as well as the increased number of potentially interfering ions, make the determination of trace levels of metal ions still challenging. A wide variety of MOF materials have been employed for the extraction of metals from sample matrices prior to their determination with spectrometric techniques.

Applications of Metal-Organic Frameworks in Food Sample Preparation.

Food samples such as milk, beverages, meat and chicken products, fish, etc. are complex and demanding matrices. Various novel materials such as molecular imprinted polymers (MIPs), carbon-based nanomaterials carbon nanotubes, graphene oxide and metal-organic frameworks (MOFs) have been recently introduced in sample preparation to improve clean up as well as to achieve better recoveries, all complying with green analytical chemistry demands. Metal-organic frameworks are hybrid organic inorganic materials, which have been used for gas storage, separation, catalysis and drug delivery. The last few years MOFs have been used for sample preparation of pharmaceutical, environmental samples and food matrices. Due to their high surface area MOFs can be used as adsorbents for the development of sample preparation techniques of food matrices prior to their analysis with chromatographic and spectrometric techniques with great performance characteristics.

A novel headspace solid-phase microextraction arrow method employing comprehensive two-dimensional gas chromatography-mass spectrometry combined with chemometric tools for the investigation of wine aging.

BACKGROUND: Omics is used as an analytical tool to investigate wine authenticity issues. Aging authentication ensures that the wine has undergone the necessary maturation and developed its desired organoleptic characteristics. Considering that aged wines constitute valuable commodities, the development of advanced omics techniques that guarantee aging authenticity and prevent fraud is essential. RESULTS: Α solid phase microextraction Arrow method combined with comprehensive two-dimensional gas chromatography-mass spectrometry was developed to identify volatiles in red wines and investigate how aging affects their volatile fingerprint. The method was optimized by examining the critical parameters that affect the solid phase microextraction Arrow extraction (stirring rate, extraction time) process. Under optimized conditions, extraction took place within 45 min under stirring at 1000 rpm. In all, 24 monovarietal red wine samples belonging to the Xinomavro variety from Naoussa (Imathia regional unit of Macedonia, Greece) produced during four different vintage years (1998, 2005, 2008 and 2015) were analyzed. Overall, 237 volatile compounds were tentatively identified and were treated with chemometric tools. Four major groups, one for each vintage year were revealed using the Hierarchical Clustering Analysis. The first two Principal Components of Principal Component Analysis explained 86.1% of the total variance, showing appropriate grouping of the wine samples produced in the same crop year. A two-way orthogonal partial least square - discriminant analysis model was developed and successfully classified all the samples to the proper class according to the vintage age, establishing 17 volatile markers as the most important features responsible for the classification, with an explained total variance of 88.5%. The developed prediction model was validated and the analyzed samples were classified with 100% accuracy according to the vintage age, based on their volatile fingerprint. SIGNIFICANCE: The developed methodology in combination with chemometric techniques allows to trace back and confirm the vintage year, and is proposed as a novel authenticity tool which opens completely new and hitherto unexplored possibilities for wine authenticity testing and confirmation.

Use of modified Doehlert-type experimental design in optimization of a hybrid electrospray ionization ion trap time-of-flight mass spectrometry technique for glutathione determination.

RATIONALE: The capabilities of modified non-spherical Doehlert-type experimental designs to optimize the performance of a hybrid mass spectrometer were investigated in this paper for the first time. The optimization process was completed in three successive steps with groups of variables avoiding any univariable approach. Glutathione (GSH, reduced) was selected as a very interesting analyte since it is considered to be one of the most abundant tripeptides in human organism and its action against xenobiotics and oxidative radicals is well known. METHODS: In particular, a tandem technique based on sequential ion management by an ion trap followed by a time-of-flight mass analyzer (ITTOFMS) was introduced commercially in recent years and investigated for glutathione determination. Glutathione was injected in a stream of a typical mobile phase used in liquid chromatography (LC) and analyzed after electrospray ionization (ESI) in tandem MS. RESULTS: The three main steps of the LC/MS system, namely the LC mobile phase, the ESI interface and the MS analyzer, were independently optimized in terms of maximum sensitivity. In this context quadratic models were found and their prediction power was evaluated. A calibration study was performed at default and optimum conditions in order to quantitatively estimate the sensitivity enhancement of the employed technique for this analyte. Satisfactory precision (RSD 5.7%) and detectability (LOD 0.07 µmol L(-1) ) were achieved. CONCLUSIONS: The results highlighted the possibilities offered by the employment of multifactorial optimization towards the improvement of performance of tandem mass spectrometry techniques.

Inhaled cisplatin deposition and distribution in lymph nodes in stage II lung cancer patients.

Lung cancer therapies during the last decade have focused on targeting the genome of cancer cells, and novel routes for administering lung cancer therapies have been investigated for decades. Aerosol therapies for several systematic diseases and systemic infections were introduced into the market a decade ago. One of the main issues of aerosol therapies has been the ability to investigate the deposition of a drug compound throughout the systematic circulation and lymph node circulation. Until now, none of the published studies have efficiently shown the deposition of a chemotherapy pharmaceutical within the lymph node tissue. In our current work we present, for the first time, with the novel CytoViva(®) (AL, USA) technique, the deposition of cisplatin aerosol therapy in surgically resected stage II lymph nodes from lung cancer patients. Finally, we present the distribution of cisplatin in correlation with the cisplatin concentration in different lymph stations and comment on the possible mechanisms of distribution.

Design and development of second-generation fabric phase sorptive extraction membranes: Proof-of-concept for the extraction of organophosphorus pesticides from apple juice prior to GC-MS analysis.

In this work, different sol-gel sorbent-coated second-generation fabric phase sorptive extraction (FPSE) membranes were synthesized using titania-based sol-gel precursors. The proposed membranes were tested for their efficiency to extract eleven selected organophosphorus pesticides (OPPs) from apple juice samples. Among the examined materials, sol-gel C18 coated titania-based FPSE membranes showed the highest extraction efficiency. These membranes were used for the optimization and validation of an FPSE method prior to analysis by gas chromatography-mass spectrometry. The detection limits for OPPs ranged between 0.03 and 0.08 ng mL-1. Moreover, the relative standard deviation was < 8.2% and 8.4% for intra-day and inter-day studies, respectively. The relative recoveries were 91-110% (intra-day study) and 90-106% (inter-day study) for all the target analytes, demonstrating good overall method accuracy. Moreover, the novel membranes were reusable at least 5 times. The titania-based membranes were compared to the conventional silica-based membranes and their utilization resulted in higher extraction recoveries.

Speciation analysis of triethyl-lead and tributyl-tin compounds in human urine by liquid-liquid extraction and gas chromatography microwave-induced plasma atomic emission detection.

This work describes the development of a fast method for speciation analysis of triethyl-lead and tributyl-tin species in urine samples after in situ derivatization by tetraethyl- or tetrapropyl-borate reagents. The alkylation reaction is done in the aqueous and urine medium and the less-polar derivatives are extracted in hexane by liquid-liquid extraction. The species were extracted and the extract was efficiently collected from the aqueous phase after centrifugation. Finally, the organometallic species are separated by gas chromatography and determined from the emission signals of elemental lead and tin. Atomic lead and tin are formed from the organolead and organotin compounds during atomization of the column eluate in a microwave-induced helium plasma source. The simultaneous measurement of lead (Pb) at 405.780 nm and tin (Sn) at 303.419 nm was achieved by an atomic emission detector. Finally, the analytes were determined with satisfactory precision (<5%) and detection limits of 0.05 µg Pb/L and 0.48 µg Sn/L, respectively, when 10 mL of urine is extracted with 1 mL of hexane and 1 µL of extract is injected.

Headspace Solid-Phase Microextraction Followed by Gas Chromatography-Mass Spectrometry as a Powerful Analytical Tool for the Discrimination of Truffle Species According to Their Volatiles.

This study provides the first assessment of the volatile metabolome map of Tuber Aestivum and Tuber Borchii originating from Greece using headspace solid-phase micro-extraction (HS-SPME) coupled to gas chromatography-mass spectrometry (GC-MS). For the extraction of the volatile fraction, the SPME protocol was optimized after examining the effects of sample mass, extraction temperature, and extraction time using the one-variable at-a-time approach (OVAT). The optimum parameters involved the extraction of 100 mg of homogenized truffle for 45 min at 50°C. Overall, 19 truffle samples were analyzed, and the acquired data were normalized and further processed with chemometrics. Agglomerative hierarchical clustering (HCA) was used to identify the groups of the two species. Partial least squares-discriminant analysis (PLS-DA) was employed to develop a chemometric model that could discriminate the truffles according to the species and reveal characteristic volatile markers for Tuber Aestivum and Tuber Borchii grown in Greece.

Fabric phase sorptive extraction combined with gas chromatography-mass spectrometry as an innovative analytical technique for the determination of selected polycyclic aromatic hydrocarbons in herbal infusions and tea samples.

This study presents a fabric phase sorptive extraction (FPSE) protocol for the isolation and preconcentration of four selected polycyclic aromatic hydrocarbons from tea samples and herbal infusions, followed by their separation and quantification by gas chromatography-mass spectrometry (GC-MS). In FPSE, extraction of the target analytes is performed utilizing a flexible fabric substrate that is coated with a highly efficient sol-gel sorbent. In this work, eighteen different FPSE membranes were examined, with the highest extraction recoveries being observed with the sol-gel C18 coated FPSE membrane. The main parameters that influence the adsorption and desorption of the PAHs were optimized and the proposed method was validated. The detection limits and the quantification limits were 0.08-0.17 ng mL-1 and 0.25-0.50 ng mL-1, respectively, for the different target compounds with a 10 mL sample. The relative standard deviations for intra-day and inter-day repeatability were less than 7.9% and 8.5%, respectively. The sol-gel C18 coated FPSE membrane could be used for at least 5 subsequent sample preparation cycles. Finally, the proposed protocol was successfully employed for the determination of PAHs in a wide range of tea and herbal infusion samples.

Exploring the volatile profile of whiskey samples using solid-phase microextraction Arrow and comprehensive two-dimensional gas chromatography-mass spectrometry.

We present a novel sample preparation method for the extraction and preconcentration of volatile organic compounds from whiskey samples prior to their determination by comprehensive two-dimensional gas chromatography (GC × GC) coupled to mass spectrometry (MS). Sample preparation of the volatile compounds, important for the organoleptic characteristics of different whiskeys and their acceptance and liking by the consumers, is based on the use of the solid-phase microextraction (SPME) Arrow. After optimization, the proposed method was compared with conventional SPME regarding the analysis of different types of whiskey (i.e., Irish whiskey, single malt Scotch whiskey and blended Scotch whiskey) and was shown to exhibit an up to a factor of six higher sensitivity and better repeatability by a factor of up to five, depending on the compound class. A total of 167 volatile organic compounds, including terpenes, alcohols, esters, carboxylic acids, ketones, were tentatively-identified using the SPME Arrow technique, while a significantly lower number of compounds (126) were determined by means of conventional SPME. SPME Arrow combined with GC × GC-MS was demonstrated to be a powerful analytical tool for the exploration of the volatile profile of complex samples, allowing to identify differences in important flavour compounds for the three different types of whiskey investigated.

Exploring sol-gel zwitterionic fabric phase sorptive extraction sorbent as a new multi-mode platform for the extraction and preconcentration of triazine herbicides from juice samples.

Triazine herbicides are a class of common pesticides which are widely used to control the weeds in many agricultural crops. Although many studies have described methodologies for the determination of triazine herbicides in aqueous samples, the attention given to agricultural crops and their products is far more limited. In this study, a novel sol-gel zwitterionic multi-mode fabric phase sorptive extraction (FPSE) platform was developed for the matrix clean-up, extraction and preconcentration of five triazine herbicides from fruit juice samples prior to their determination by high performance liquid chromatography-diode array detection (HPLC-DAD). The novel zwitterionic multi-mode sorbent was characterized and its performance for fruit juice analysis was evaluated. Compared to other sol-gel sorbents, the novel zwitterionic sorbent helped cleaning all the acidic interferences from fruit juices. The herein reported FPSE protocol was optimized and validated. Under optimum conditions, the FPSE method showed good accuracy, precision and sensitivity. The limits of detection and limits of quantification for all analytes were 0.15 ng mL-1 and 0.50 ng mL-1, respectively. The enhancement factors of this method ranged between 36.7 and 51.8. The relative standard deviation for intra-day precision was below 5.6% and for inter-day precision was below 8.8%. Finally, the proposed FPSE-HPLC-DAD method was successfully employed for the analysis of various fruit juice samples.

Magnet integrated fabric phase sorptive extraction as a stand-alone extraction device for the monitoring of benzoyl urea insecticides in water samples by HPLC-DAD.

Benzoyl urea insecticides are a class of pesticides used in agriculture for the inhibition of chitin synthesis in pests. These compounds are persistent in environmental samples, and thus their monitoring is necessary to avoid detrimental effects to human health and the environment. Magnet integrated fabric phase sorptive extraction (MI-FPSE) is a recently introduced sample preparation technique that combines sample stirring and analyte extraction into one stand-alone device. However, the applicability and the potential benefits of this technique in environmental analysis remain unexplored. In the present study, MI-FPSE was employed for the first time for the extraction and preconcentration of benzoyl urea insecticides (i.e., diflubenzuron, triflumuron, hexaflumuron, lufenuron and chlorfluazuron) from environmental water samples prior to their determination by high performance liquid chromatography-diode array detection (HPLC-DAD). The main factors affecting the performance of the proposed methodology were thoroughly investigated and optimized and the MI-FPSE-HPLC-DAD method was validated. The proposed method enabled the handling of relatively high sample quantity resulting in high preconcentration factors (501 and 731) and good sensitivity. Under optimum conditions, the limits of detection and the limits of quantification for the benzoyl urea insecticides were 0.06 ng mL-1 and 0.20 ng mL-1, respectively. Moreover, the relative standard deviations were less than 6.1% for intra-day study and less than 8.2% for inter-day study showing good method precision. After its validation, the herein developed method was successfully employed for the analysis of tap, mineral, river, and lake water samples. In addition, the ComplexGAPI index was used to present the green potential of developed method from the step of MI-FPSE device preparation to final determination. All things considered, MI-FPSE could potentially serve as an efficient tool for the monitoring of pollutants in environmental analysis.