Editorial

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2 pages, 172 KiB

Open AccessEditorial

Editorial for Special Issue “Sample Preparation-Quo Vadis: Current Status of Sample Preparation Approaches-2nd Edition”

by Victoria Samanidou and Irene Panderi

Molecules 2022, 27(19), 6142; https://doi.org/10.3390/molecules27196142 - 20 Sep 2022

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Abstract

Sample preparation is and will always be the most important step in chemical analysis [...] Full article

(This article belongs to the Special Issue Sample Preparation-Quo Vadis: Current Status of Sample Preparation Approaches-2nd Edition)

Research

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22 pages, 4036 KiB

Open AccessArticle

Comparative Study of Sample Carriers for the Identification of Volatile Compounds in Biological Fluids Using Raman Spectroscopy

by Panagiota Papaspyridakou, Michail Lykouras, Christos Kontoyannis and Malvina Orkoula

Molecules 2022, 27(10), 3279; https://doi.org/10.3390/molecules27103279 - 20 May 2022

Cited by 4 | Viewed by 1714

Abstract

Vibrational spectroscopic techniques and especially Raman spectroscopy are gaining ground in substituting the officially established chromatographic methods in the identification of ethanol and other volatile substances in body fluids, such as blood, urine, saliva, semen, and vaginal fluids. Although a couple of different [...] Read more.

Vibrational spectroscopic techniques and especially Raman spectroscopy are gaining ground in substituting the officially established chromatographic methods in the identification of ethanol and other volatile substances in body fluids, such as blood, urine, saliva, semen, and vaginal fluids. Although a couple of different carriers and substrates have been employed for the biochemical analysis of these samples, most of them are suffering from important weaknesses as far as the analysis of volatile compounds is concerned. For this reason, in this study three carriers are proposed, and the respective sample preparation methods are described for the determination of ethanol in human urine samples. More specifically, a droplet of the sample on a highly reflective carrier of gold layer, a commercially available cuvette with a mirror to enhance backscattered radiation sealed with a lid, and a home designed microscope slide with a cavity coated with gold layer and covered with transparent cling film have been evaluated. Among the three proposed carriers, the last one achieved a quick, simple, and inexpensive identification of ethanol, which was used as a case study for the volatile compound, in the biological samples. The limit of detection (LoD) was found to be 1.00 μL/mL, while at the same time evaporation of ethanol was prevented. Full article

(This article belongs to the Special Issue Sample Preparation-Quo Vadis: Current Status of Sample Preparation Approaches-2nd Edition)

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16 pages, 3532 KiB

Open AccessArticle

A Simple and Reliable Dispersive Liquid-Liquid Microextraction with Smartphone-Based Digital Images for Determination of Carbaryl Residues in Andrographis paniculata Herbal Medicines Using Simple Peroxidase Extract from Senna siamea Lam. Bark

by Sam-ang Supharoek, Watsaka Siriangkhawut, Kate Grudpan and Kraingkrai Ponhong

Molecules 2022, 27(10), 3261; https://doi.org/10.3390/molecules27103261 - 19 May 2022

Cited by 3 | Viewed by 1827

Abstract

A simple and reliable dispersive liquid-liquid microextraction (DLLME) coupled with smartphone-based digital images using crude peroxidase extracts from cassia bark (Senna siamea Lam.) was proposed to determine carbaryl residues in Andrographis paniculata herbal medicines. The method was based on the reaction of [...] Read more.

A simple and reliable dispersive liquid-liquid microextraction (DLLME) coupled with smartphone-based digital images using crude peroxidase extracts from cassia bark (Senna siamea Lam.) was proposed to determine carbaryl residues in Andrographis paniculata herbal medicines. The method was based on the reaction of 1-naphthol (hydrolysis of carbaryl) with 4-aminoantipyrine (4-AP) in the presence of hydrogen peroxide, using peroxidase enzyme simple extracts from cassia bark as biocatalysts under pH 6.0. The red product, after preconcentration by DLLME using dichloromethane as extraction solvent, was measured for blue intensity by daily life smartphone-based digital image analysis. Under optimized conditions, good linearity of the calibration graph was found at 0.10–0.50 mg·L⁻¹ (r² = 0.9932). Limits of detection (LOD) (3SD/slope) and quantification (LOQ) (10SD/slope) were 0.03 and 0.09 mg·L⁻¹, respectively, with a precision of less than 5%. Accuracy of the proposed method as percentage recovery gave satisfactory results. The proposed method was successfully applied to analyze carbaryl in Andrographis paniculata herbal medicines. Results agreed well with values obtained from the HPLC-UV method at 95% confidence level. This was simple, convenient, reliable, cost-effective and traceable as an alternative method for the determination of carbaryl. Full article

(This article belongs to the Special Issue Sample Preparation-Quo Vadis: Current Status of Sample Preparation Approaches-2nd Edition)

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12 pages, 4257 KiB

Open AccessArticle

Measuring Bismuth Oxide Particle Size and Morphology in Film-Coated Tablets

by Stefani Fertaki, Georgios Bagourakis, Malvina Orkoula and Christos Kontoyannis

Molecules 2022, 27(8), 2602; https://doi.org/10.3390/molecules27082602 - 18 Apr 2022

Viewed by 1884

Abstract

The assessment of active pharmaceutical ingredient (API) particle size and morphology is of great importance for the pharmaceutical industry since it is expected to significantly affect physicochemical properties. However, very few methods are published for the determination of API morphology and particle size [...] Read more.

The assessment of active pharmaceutical ingredient (API) particle size and morphology is of great importance for the pharmaceutical industry since it is expected to significantly affect physicochemical properties. However, very few methods are published for the determination of API morphology and particle size of film-coated (FC) tablets. In the current study we provide a methodology for the measurement of API particle size and morphology which could be applied in several final products. Bismuth Oxide 120 mg FC Tabs were used for our method development, which contain bismuth oxide (as tripotassium dicitratobismuthate (bismuth subcitrate)) as the active substance. The sample preparation consists of partial excipient dissolution in different solvents. Following this procedure, the API particles were successfully extracted from the granules. Particle size and morphology identification in Bismuth Oxide 120 mg FC Tabs was conducted using micro-Raman mapping spectroscopy and ImageJ software. The proposed methodology was repeated for the raw API material and against a reference listed drug (RLD) for comparative purposes. The API particle size was found to have decreased compared to the raw API, while the API morphology was also affected from the formulation manufacturing process. Comparison with the RLD product also revealed differences, mainly in the API particle size and secondarily in the crystal morphology. Full article

(This article belongs to the Special Issue Sample Preparation-Quo Vadis: Current Status of Sample Preparation Approaches-2nd Edition)

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11 pages, 1396 KiB

Open AccessArticle

Microwave-Assisted Extraction Coupled to HPLC-UV Combined with Chemometrics for the Determination of Bioactive Compounds in Pistachio Nuts and the Guarantee of Quality and Authenticity

by Natasa P. Kalogiouri, Petros D. Mitsikaris, Athanasios N. Papadopoulos and Victoria F. Samanidou

Molecules 2022, 27(4), 1435; https://doi.org/10.3390/molecules27041435 - 21 Feb 2022

Cited by 2 | Viewed by 2040

Abstract

Two novel microwave-assisted extraction (MAE) methods were developed for the isolation of phenols and tocopherols from pistachio nuts. The extracts were analyzed by reversed-phase high-pressure liquid chromatography coupled with a UV detector (RP-HPLC-UV). In total, eighteen pistachio samples, originating from Greece and Turkey, [...] Read more.

Two novel microwave-assisted extraction (MAE) methods were developed for the isolation of phenols and tocopherols from pistachio nuts. The extracts were analyzed by reversed-phase high-pressure liquid chromatography coupled with a UV detector (RP-HPLC-UV). In total, eighteen pistachio samples, originating from Greece and Turkey, were analyzed and thirteen phenolic compounds, as well as α-tocopherol, (β + γ)-tocopherol, and δ-tocopherol, were identified. The analytical methods were validated and presented good linearity (r² > 0.990) and a high recovery rate over the range of 82.4 to 95.3% for phenols, and 93.1 to 96.4% for tocopherols. Repeatablility was calculated over the range 1.8–5.8%RSD for intra-day experiments, and reproducibility over the range 3.2–9.4%RSD for inter-day experiments, respectively. Principal component analysis (PCA) was employed to analyze the differences between the concentrations of the bioactive compounds with respect to geographical origin, while agglomerative hierarchical clustering (AHC) was used to cluster the samples based on their similarity and according to the geographical origin. Full article

(This article belongs to the Special Issue Sample Preparation-Quo Vadis: Current Status of Sample Preparation Approaches-2nd Edition)

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13 pages, 1705 KiB

Open AccessFeature PaperArticle

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

by Natalia Manousi, Abuzar Kabir, Kenneth G. Furton, George A. Zachariadis and Aristidis Anthemidis

Molecules 2021, 26(15), 4461; https://doi.org/10.3390/molecules26154461 - 24 Jul 2021

Cited by 11 | Viewed by 2528

Abstract

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). [...] Read more.

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. Full article

(This article belongs to the Special Issue Sample Preparation-Quo Vadis: Current Status of Sample Preparation Approaches-2nd Edition)

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15 pages, 1914 KiB

Open AccessArticle

Fluorimetric Analysis of Five Amino Acids in Chocolate: Development and Validation

by Maria S. Synaridou, Vasilis Tsamis, Georgia Sidiropoulou, Constantinos K. Zacharis, Irene Panderi and Catherine K. Markopoulou

Molecules 2021, 26(14), 4325; https://doi.org/10.3390/molecules26144325 - 16 Jul 2021

Cited by 3 | Viewed by 2470

Abstract

Amino acids present ergogenic action, helping to increase, protect, and restore the muscular system of young athletes. Moreover, the encapsulation of five relevant amino acids in chocolate pellet form will appeal to them, facilitating their daily consumption. A reliable HPLC fluorimetric method was [...] Read more.

Amino acids present ergogenic action, helping to increase, protect, and restore the muscular system of young athletes. Moreover, the encapsulation of five relevant amino acids in chocolate pellet form will appeal to them, facilitating their daily consumption. A reliable HPLC fluorimetric method was developed to detect and quantitatively determine L-Leucine, L-Isoleucine, L-Histidine, L-Valine, and β-Alanine in chocolate using aniline as an internal standard. Experimental design methodology was used to investigate and optimize the clean-up procedure of the samples. Therefore, three extraction techniques (solid-phase extraction (by two different SPE cartridges) and liquid–solid extraction (LSE)) were compared and evaluated. The LOQ values in chocolate varied from 24 to 118 ng/g (recovery 89.7–95.6%, %RSD < 2.5). Amino acids were pre-column derivatized with o-phthalaldehyde (OPA), while derivatization parameters were thoroughly investigated by experimental design methodology. The analysis was performed by HPLC-fluorescence (emission: λ = 455 nm, excitation: λ = 340 nm) method using a C₁₈ column and a mixture of phosphate buffer (pH = 2.8; 20 mM)-methanol as a mobile phase in gradient elution. The method was validated (r² > 0.999, %RSD < 2, LOD: 10 ng mL⁻¹ for histidine and leucine, 2 ng mL⁻¹ for alanine and valine, and 4 ng mL⁻¹ for Isoleucine) according to the International Conference on Harmonization guidelines. Full article

(This article belongs to the Special Issue Sample Preparation-Quo Vadis: Current Status of Sample Preparation Approaches-2nd Edition)

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18 pages, 1715 KiB

Open AccessArticle

Application of Bar Adsorptive Microextraction for the Determination of Levels of Tricyclic Antidepressants in Urine Samples

by Mariana N. Oliveira, Oriana C. Gonçalves, Samir M. Ahmad, Jaderson K. Schneider, Laiza C. Krause, Nuno R. Neng, Elina B. Caramão and José M. F. Nogueira

Molecules 2021, 26(11), 3101; https://doi.org/10.3390/molecules26113101 - 22 May 2021

Cited by 9 | Viewed by 2203

Abstract

This work entailed the development, optimization, validation, and application of a novel analytical approach, using the bar adsorptive microextraction technique (BAμE), for the determination of the six most common tricyclic antidepressants (TCAs; amitriptyline, mianserin, trimipramine, imipramine, mirtazapine and dosulepin) in urine matrices. To [...] Read more.

This work entailed the development, optimization, validation, and application of a novel analytical approach, using the bar adsorptive microextraction technique (BAμE), for the determination of the six most common tricyclic antidepressants (TCAs; amitriptyline, mianserin, trimipramine, imipramine, mirtazapine and dosulepin) in urine matrices. To achieve this goal, we employed, for the first time, new generation microextraction devices coated with convenient sorbent phases, polymers and novel activated carbons prepared from biomaterial waste, in combination with large-volume-injection gas chromatography-mass spectrometry operating in selected-ion monitoring mode (LVI-GC-MS(SIM)). Preliminary assays on sorbent coatings, showed that the polymeric phases present a much more effective performance, as the tested biosorbents exhibited low efficiency for application in microextraction techniques. By using BAμE coated with C₁₈ polymer, under optimized experimental conditions, the detection limits achieved for the six TCAs ranged from 0.2 to 1.6 μg L⁻¹ and, weighted linear regressions resulted in remarkable linearity (r² > 0.9960) between 10.0 and 1000.0 μg L⁻¹. The developed analytical methodology (BAμE(C18)/LVI-GC-MS(SIM)) provided suitable matrix effects (90.2–112.9%, RSD ≤ 13.9%), high recovery yields (92.3–111.5%, RSD ≤ 12.3%) and a remarkable overall process efficiency (ranging from 84.9% to 124.3%, RSD ≤ 13.9%). The developed and validated methodology was successfully applied for screening the six TCAs in real urine matrices. The proposed analytical methodology proved to be an eco-user-friendly approach to monitor trace levels of TCAs in complex urine matrices and an outstanding analytical alternative in comparison with other microextraction-based techniques. Full article

(This article belongs to the Special Issue Sample Preparation-Quo Vadis: Current Status of Sample Preparation Approaches-2nd Edition)

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9 pages, 1966 KiB

Open AccessArticle

Micro Salting-Out Assisted Matrix Solid-Phase Dispersion: A Simple and Fast Sample Preparation Method for the Analysis of Bisphenol Contaminants in Bee Pollen

by Jianing Zhang, Fengjie Yu, Yunmin Tao, Chunping Du, Wenchao Yang, Wenbin Chen and Xijuan Tu

Molecules 2021, 26(8), 2350; https://doi.org/10.3390/molecules26082350 - 18 Apr 2021

Cited by 7 | Viewed by 2219

Abstract

In the present work, a novel sample preparation method, micro salting-out assisted matrix solid-phase dispersion (μ-SOA-MSPD), was developed for the determination of bisphenol A (BPA) and bisphenol B (BPB) contaminants in bee pollen. The proposed method was designed to combine two classical sample [...] Read more.

In the present work, a novel sample preparation method, micro salting-out assisted matrix solid-phase dispersion (μ-SOA-MSPD), was developed for the determination of bisphenol A (BPA) and bisphenol B (BPB) contaminants in bee pollen. The proposed method was designed to combine two classical sample preparation methodologies, matrix solid-phase dispersion (MSPD) and homogenous liquid-liquid extraction (HLLE), to simplify and speed-up the preparation process. Parameters of μ-SOA-MSPD were systematically investigated, and results indicated the significant effect of salt and ACN-H₂O extractant on the signal response of analytes. In addition, excellent clean-up ability in removing matrix components was observed when primary secondary amine (PSA) sorbent was introduced into the blending operation. The developed method was fully validated, and the limits of detection for BPA and BPB were 20 μg/kg and 30 μg/kg, respectively. Average recoveries and precisions were ranged from 83.03% to 94.64% and 1.76% to 5.45%, respectively. This is the first report on the analysis of bisphenol contaminants in bee pollen sample, and also on the combination of MSPD and HLLE. The present method might provide a new strategy for simple and fast sample preparation of solid and semi-solid samples. Full article

(This article belongs to the Special Issue Sample Preparation-Quo Vadis: Current Status of Sample Preparation Approaches-2nd Edition)

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Review

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29 pages, 2039 KiB

Open AccessReview

Green Extraction Techniques as Advanced Sample Preparation Approaches in Biological, Food, and Environmental Matrices: A Review

by José S. Câmara, Rosa Perestrelo, Cristina V. Berenguer, Carolina F. P. Andrade, Telma M. Gomes, Basit Olayanju, Abuzar Kabir, Cristina M. R. Rocha, José António Teixeira and Jorge A. M. Pereira

Molecules 2022, 27(9), 2953; https://doi.org/10.3390/molecules27092953 - 06 May 2022

Cited by 56 | Viewed by 6705

Abstract

Green extraction techniques (GreETs) emerged in the last decade as greener and sustainable alternatives to classical sample preparation procedures aiming to improve the selectivity and sensitivity of analytical methods, simultaneously reducing the deleterious side effects of classical extraction techniques (CETs) for both the [...] Read more.

Green extraction techniques (GreETs) emerged in the last decade as greener and sustainable alternatives to classical sample preparation procedures aiming to improve the selectivity and sensitivity of analytical methods, simultaneously reducing the deleterious side effects of classical extraction techniques (CETs) for both the operator and the environment. The implementation of improved processes that overcome the main constraints of classical methods in terms of efficiency and ability to minimize or eliminate the use and generation of harmful substances will promote more efficient use of energy and resources in close association with the principles supporting the concept of green chemistry. The current review aims to update the state of the art of some cutting-edge GreETs developed and implemented in recent years focusing on the improvement of the main analytical features, practical aspects, and relevant applications in the biological, food, and environmental fields. Approaches to improve and accelerate the extraction efficiency and to lower solvent consumption, including sorbent-based techniques, such as solid-phase microextraction (SPME) and fabric-phase sorbent extraction (FPSE), and solvent-based techniques (μQuEChERS; micro quick, easy, cheap, effective, rugged, and safe), ultrasound-assisted extraction (UAE), and microwave-assisted extraction (MAE), in addition to supercritical fluid extraction (SFE) and pressurized solvent extraction (PSE), are highlighted. Full article

(This article belongs to the Special Issue Sample Preparation-Quo Vadis: Current Status of Sample Preparation Approaches-2nd Edition)

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23 pages, 998 KiB

Open AccessReview

Factors Affecting Preparation of Molecularly Imprinted Polymer and Methods on Finding Template-Monomer Interaction as the Key of Selective Properties of the Materials

by Aliya Nur Hasanah, Nisa Safitri, Aulia Zulfa, Neli Neli and Driyanti Rahayu

Molecules 2021, 26(18), 5612; https://doi.org/10.3390/molecules26185612 - 16 Sep 2021

Cited by 57 | Viewed by 6403

Abstract

Molecular imprinting is a technique for creating artificial recognition sites on polymer matrices that complement the template in terms of size, shape, and spatial arrangement of functional groups. The main advantage of Molecularly Imprinted Polymers (MIP) as the polymer for use with a [...] Read more.

Molecular imprinting is a technique for creating artificial recognition sites on polymer matrices that complement the template in terms of size, shape, and spatial arrangement of functional groups. The main advantage of Molecularly Imprinted Polymers (MIP) as the polymer for use with a molecular imprinting technique is that they have high selectivity and affinity for the target molecules used in the molding process. The components of a Molecularly Imprinted Polymer are template, functional monomer, cross-linker, solvent, and initiator. Many things determine the success of a Molecularly Imprinted Polymer, but the Molecularly Imprinted Polymer component and the interaction between template-monomers are the most critical factors. This review will discuss how to find the interaction between template and monomer in Molecularly Imprinted Polymer before polymerization and after polymerization and choose the suitable component for MIP development. Computer simulation, UV-Vis spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR), Proton-Nuclear Magnetic Resonance (¹H-NMR) are generally used to determine the type and strength of intermolecular interaction on pre-polymerization stage. In turn, Suspended State Saturation Transfer Difference High Resolution/Magic Angle Spinning (STD HR/MAS) NMR, Raman Spectroscopy, and Surface-Enhanced Raman Scattering (SERS) and Fluorescence Spectroscopy are used to detect chemical interaction after polymerization. Hydrogen bonding is the type of interaction that is becoming a focus to find on all methods as this interaction strongly contributes to the affinity of molecularly imprinted polymers (MIPs). Full article

(This article belongs to the Special Issue Sample Preparation-Quo Vadis: Current Status of Sample Preparation Approaches-2nd Edition)

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