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Method Development of Sampling Preparation Techniques

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A special issue of Molecules (ISSN 1420-3049). This special issue belongs to the section "Analytical Chemistry".

Deadline for manuscript submissions: closed (31 May 2022) | Viewed by 41012

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Dr. Giorgio Marrubini

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Department of Drug Sciences, University of Pavia, Pavia, Italy
Interests: analytical chemistry; pharmaceutical analysis; analytical toxicology; method validation; robustness testing; chromatographic techniques; data analysis; design of experiments (DoE)
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Special Issue Information

Dear Colleagues,

Method development and validation are fundamental phases of the life-cycle of measurement procedures in analytical chemistry. The approaches to method development are limited and rely on the skills and culture of the researchers. Validation, instead, is in most fields described as a list of requirements that the method must fulfill to ensure the quality and reliability of the results.

Following the success of two Special Issues of Molecules dedicated to solid-phase microextraction (SPME), and to Method Development and Validation in Food and Pharmaceutical Analysis, in collaboration with the editors of the journal, we have decided to edit a Special Issue dedicated to the strategies for method development and validation of sampling preparation techniques.

We aim to collect studies describing the approaches adopted for the development and validation of methods, including not only miniaturized extraction techniques coupled to chromatography instruments (HPLC, GC) but also offline extraction techniques such as ultrasonic-assisted and microwave-assisted extraction techniques. Studies could also focus on recent robotic automation techniques applied to innovative extraction, purification, and concentration of biological/environmental matrices, in order to minimize resource consumption (economic and human), in line with what is required by current international requirements and regulations.

This Special Issue on “Method Development of Sampling Preparation Techniques” aims to cover research trends in the development of new analytical and bioanalytical methods relevant to the isolation, separation, identification, and determination of substances in biomedical, forensic, industrial hygiene, pharmaceutical, and food analysis.

Dr. Giorgio Marrubini
Guest Editor

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Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Molecules is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2700 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

Method development
Sample preparation
Robotic automation techniques
Innovative procedures
Green chemistry

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Published Papers (10 papers)

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Research

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12 pages, 1282 KiB

Open AccessArticle

Guiding Molecularly Imprinted Polymer Design by Pharmacophore Modeling

by Wiebke Derz, Melita Fleischmann and Paul W. Elsinghorst

Molecules 2021, 26(16), 5101; https://doi.org/10.3390/molecules26165101 - 23 Aug 2021

Cited by 4 | Viewed by 2931

Abstract

Molecularly imprinted polymers (MIP) combine the selectivity of immunoaffinity chromatography with the robustness of common solid-phase extraction in what is referred to as molecularly imprinted solid-phase extraction (MISPE). This contribution shows how MIP design may be guided by pharmacophore modeling for the example of citrinin, which is an emerging mycotoxin from cereals. The obtained pharmacophore model allowed searching public databases for a set of citrinin-mimicking molecular surrogates. Imprinted and non-imprinted polymers were subsequently obtained through bulk and core-shell polymerization in the presence of these surrogates. Evaluation of their binding ability for citrinin and structurally related ochratoxin A revealed a promising MIP derived from rhodizonic acid. A protocol for MISPE of citrinin from cereals was subsequently developed and compared to immunoaffinity chromatography with respect to clean-up efficiency and recovery. Full article

(This article belongs to the Special Issue Method Development of Sampling Preparation Techniques)

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21 pages, 5130 KiB

Open AccessArticle

Effect of Sample Preparation on the Detection and Quantification of Selected Nuts Allergenic Proteins by LC-MS/MS

by Sorel Tchewonpi Sagu, Gerd Huschek, Thomas Homann and Harshadrai M. Rawel

Molecules 2021, 26(15), 4698; https://doi.org/10.3390/molecules26154698 - 3 Aug 2021

Cited by 14 | Viewed by 5017

Abstract

The detection and quantification of nut allergens remains a major challenge. The liquid chroma-tography tandem mass spectrometry (LC-MS/MS) is emerging as one of the most widely used methods, but sample preparation prior to the analysis is still a key issue. The objective of this work was to establish optimized protocols for extraction, tryptic digestion and LC-MS analysis of almond, cashew, hazelnut, peanut, pistachio and walnut samples. Ammonium bicar-bonate/urea extraction (Ambi/urea), SDS buffer extraction (SDS), polyvinylpolypyrroli-done (PVPP) extraction, trichloroacetic acid/acetone extraction (TCA/acetone) and chloro-form/methanol/sodium chloride precipitation (CM/NaCl) as well as the performances of con-ventional tryptic digestion and microwave-assisted breakdown were investigated. Overall, the protein extraction yields ranged from 14.9 ± 0.5 (almond extract from CM/NaCl) to 76.5 ± 1.3% (hazelnut extract from Ambi/urea). Electrophoretic profiling showed that the SDS extraction method clearly presented a high amount of extracted proteins in the range of 0–15 kDa, 15–35 kDa, 35–70 kDa and 70–250 kDa compared to the other methods. The linearity of the LC-MS methods in the range of 0 to 0.4 µg equivalent defatted nut flour was assessed and recovery of internal standards GWGG and DPLNV(d8)LKPR ranged from 80 to 120%. The identified bi-omarkers peptides were used to relatively quantifier selected allergenic protein form the inves-tigated nut samples. Considering the overall results, it can be concluded that SDS buffer allows a better protein extraction from almond, peanut and walnut samples while PVPP buffer is more appropriate for cashew, pistachio and hazelnut samples. It was also found that conventional overnight digestion is indicated for cashew, pistachio and hazelnut samples, while microwave assisted tryptic digestion is recommended for almond, hazelnut and peanut extracts. Full article

(This article belongs to the Special Issue Method Development of Sampling Preparation Techniques)

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16 pages, 1385 KiB

Open AccessArticle

Optimization of Sample Preparation for Metabolomics Exploration of Urine, Feces, Blood and Saliva in Humans Using Combined NMR and UHPLC-HRMS Platforms

by Cécile Martias, Nadine Baroukh, Sylvie Mavel, Hélène Blasco, Antoine Lefèvre, Léa Roch, Frédéric Montigny, Julie Gatien, Laurent Schibler, Diane Dufour-Rainfray, Lydie Nadal-Desbarats and Patrick Emond

Molecules 2021, 26(14), 4111; https://doi.org/10.3390/molecules26144111 - 6 Jul 2021

Cited by 38 | Viewed by 6314

Abstract

Currently, most clinical studies in metabolomics only consider a single type of sample such as urine, plasma, or feces and use a single analytical platform, either NMR or MS. Although some studies have already investigated metabolomics data from multiple fluids, the information is limited to a unique analytical platform. On the other hand, clinical studies investigating the human metabolome that combine multi-analytical platforms have focused on a single biofluid. Combining data from multiple sample types for one patient using a multimodal analytical approach (NMR and MS) should extend the metabolome coverage. Pre-analytical and analytical phases are time consuming. These steps need to be improved in order to move into clinical studies that deal with a large number of patient samples. Our study describes a standard operating procedure for biological specimens (urine, blood, saliva, and feces) using multiple platforms (¹H-NMR, RP-UHPLC-MS, and HILIC-UHPLC-MS). Each sample type follows a unique sample preparation procedure for analysis on a multi-platform basis. Our method was evaluated for its robustness and was able to generate a representative metabolic map. Full article

(This article belongs to the Special Issue Method Development of Sampling Preparation Techniques)

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8 pages, 744 KiB

Open AccessArticle

The Effect of Blood Contained in the Samples on the Metabolomic Profile of Mouse Brain Tissue: A Study by NMR Spectroscopy

by Anastasia Glinskikh, Olga Snytnikova, Ekaterina Zelentsova, Maria Borisova, Yuri Tsentalovich and Andrey Akulov

Molecules 2021, 26(11), 3096; https://doi.org/10.3390/molecules26113096 - 22 May 2021

Cited by 9 | Viewed by 2539

Abstract

(1) Recently, metabolic profiling of the tissue in the native state or extracts of its metabolites has become increasingly important in the field of metabolomics. An important factor, in this case, is the presence of blood in a tissue sample, which can potentially lead to a change in the concentration of tissue metabolites and, as a result, distortion of experimental data and their interpretation. (2) In this paper, the metabolomic profiling based on NMR spectroscopy was performed to determine the effect of blood contained in the studied samples of brain tissue on their metabolomic profile. We used 13 male laboratory CD-1^® IGS mice for this study. The animals were divided into two groups. The first group of animals (n = 7) was subjected to the perfusion procedure, and the second group of animals (n = 6) was not perfused. The brain tissues of the animals were homogenized, and the metabolite fraction was extracted with a water/methanol/chloroform solution. Samples were studied by high-frequency ¹H-NMR spectroscopy with subsequent statistical data analysis. The group comparison was performed with the use of the Student’s test. We identified 36 metabolites in the brain tissue with the use of NMR spectroscopy. (3) For the major set of studied metabolites, no significant differences were found in the brain tissue metabolite concentrations in the native state and after the blood removal procedure. (4) Thus, it was shown that the presence of blood does not have a significant effect on the metabolomic profile of the brain in animals without pathologies. Full article

(This article belongs to the Special Issue Method Development of Sampling Preparation Techniques)

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10 pages, 2359 KiB

Open AccessCommunication

N-Glycomics of Cerebrospinal Fluid: Method Comparison

by Byeong Gwan Cho, Cristian D. Gutierrez Reyes and Yehia Mechref

Molecules 2021, 26(6), 1712; https://doi.org/10.3390/molecules26061712 - 19 Mar 2021

Cited by 9 | Viewed by 2901

Abstract

Cerebrospinal fluid (CSF) contains valuable biological and neurological information. However, its glycomics analysis is hampered due to the low amount of protein in the biofluid, as has been demonstrated by other glycomics studies using a substantial amount of CSF. In this work, we investigated different N-glycan sample preparation approaches to develop a more sensitive method. These methods, one with an increased amount of buffer solution during the N-glycan release step with a lower amount of sample volume and the other with Filter-Aided N-Glycan Separation (FANGS), were compared with recent work to demonstrate their effectiveness. It was demonstrated that an increased amount of buffer solution showed higher intensity in comparison to the previously published method and FANGS. This suggested that digestion efficiency during the N-glycan release step was not in an optimal condition from the previously published method, and that there is a substantial loss of sample with FANGS when preparing N-glycans from CSF. Full article

(This article belongs to the Special Issue Method Development of Sampling Preparation Techniques)

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10 pages, 4911 KiB

Open AccessArticle

On-Line Preconcentration and Simultaneous Determination of Cu and Mn in Water Samples Using a Minicolumn Packed with Sisal Fiber by MIP OES

by Javier Silva and Mariela Pistón

Molecules 2021, 26(6), 1662; https://doi.org/10.3390/molecules26061662 - 16 Mar 2021

Cited by 4 | Viewed by 1912

Abstract

An on-line preconcentration system for the simultaneous determination of Copper (Cu) and manganese (Mn) in water samples was developed and coupled to a microwave-induced plasma optical emission spectrometer (MIP OES). The flow injection system was designed with a minicolumn packed with sisal fiber (Agave sisalana). A multivariate experimental design was performed to evaluate the influence of pH, preconcentration time, and eluent concentration. Optimal conditions for sample preparation were pH 5.5, preconcentration time was 90 s, and HCl 0.5 mol L⁻¹ was the eluent. The main figures of merit were detection limits 3.7 and 9.0 µg L⁻¹ for Cu and Mn, respectively. Precision was expressed as a relative standard deviation better than 10%. Accuracy was evaluated via spiked recovery assays with recoveries between 75–125%. The enrichment factor was 30 for both analytes. These results were adequate for water samples analysis for monitoring purposes. The preconcentration system was coupled and synchronized with the MIP OES nebulizer to allow simultaneous determination of Cu and Mn as a novel sample introduction strategy. The sampling rate was 20 samples/h. Sisal fiber resulted an economical biosorbent for trace element preconcentration without extra derivatization steps and with an awfully time of use without replacement complying with the principles of green analytical methods. Full article

(This article belongs to the Special Issue Method Development of Sampling Preparation Techniques)

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16 pages, 3931 KiB

Open AccessArticle

Novel Fast Chromatography-Tandem Mass Spectrometric Quantitative Approach for the Determination of Plant-Extracted Phytosterols and Tocopherols

by George Gachumi, Alice Demelenne, Asmita Poudel, Zafer Dallal Bashi and Anas El-Aneed

Molecules 2021, 26(5), 1402; https://doi.org/10.3390/molecules26051402 - 5 Mar 2021

Cited by 9 | Viewed by 3284

Abstract

Phytosterols and tocopherols are commonly used in food and pharmaceutical industries for their health benefits. Current analysis methods rely on conventional liquid chromatography, using an analytical column, which can be tedious and time consuming. However, simple, and fast analytical methods can facilitate their qualitative and quantitative analysis. In this study, a fast chromatography-tandem mass spectrometric (FC-MS/MS) method was developed and validated for the quantitative analysis of phytosterols and tocopherols. Omitting chromatography by employing flow injection analysis—mass spectrometry (FIA-MS) failed in the quantification of target analytes due to analyte-to-analyte interferences from phytosterols. These interferences arise from their ambiguous MS fingerprints that would lead to false identification and inaccurate quantification. Therefore, a C18 guard column with a 1.9 µm particle size was employed for FC-MS/MS under isocratic elution using acetonitrile/methanol (99:1 v/v) at a flow rate of 600 µL/min. Analyte-to-analyte interferences were identified and eliminated. The false peaks could then be easily identified due to chromatographic separation. In addition, two internal standards were evaluated, namely cholestanol and deuterated cholesterol. Both internal standards contributed to the observed analyte-to-analyte interferences; however, adequate shift in the retention time for deuterated cholesterol eliminated its interferences and allowed for an accurate quantification. The method is fast (1.3 min) compared to published methods and can distinguish false peaks observed in FIA-MS. Seven analytes were quantified simultaneously, namely brassicasterol, campesterol, stigmasterol, β-sitosterol, α-tocopherol, δ-tocopherol, and γ-tocopherol. The method was successfully applied in the quantitative analysis of phytosterols and tocopherols present in the unsaponifiable matter of canola oil deodorizer distillate (CODD). β-sitosterol and γ-tocopherol were the most abundant phytosterols and tocopherols, respectively. Full article

(This article belongs to the Special Issue Method Development of Sampling Preparation Techniques)

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16 pages, 1289 KiB

Open AccessArticle

UHPLC-UV/PDA Method Validation for Simultaneous Quantification of Luteolin and Apigenin Derivatives from Elaeis guineensis Leaf Extracts: An Application for Antioxidant Herbal Preparation

by Mohamad Shazeli Che Zain, Muhamad Faris Osman, Soo Yee Lee and Khozirah Shaari

Molecules 2021, 26(4), 1084; https://doi.org/10.3390/molecules26041084 - 19 Feb 2021

Cited by 14 | Viewed by 4686

Abstract

Luteolin and apigenin derivatives present in oil palm (Elaeis guineensis) leaves (OPL) are reported to possess excellent antioxidant properties relating to numerous health benefits. To meet the global demand for flavonoids, OPL, which is plentifully generated as an agricultural by-product from oil palm plantations, can be further exploited as a new source of natural antioxidant compounds. However, to produce a standardized herbal preparation, validation of the quantification method for these compounds is required. Therefore, in this investigation, we developed and validated an improved and rapid analytical method, ultra-high-performance liquid chromatography equipped with ultraviolet/photodiode array (UHPLC-UV/PDA) for the quantification of 12 luteolin and apigenin derivatives, particularly focusing on flavonoid isomeric pairs: orientin/isoorientin and vitexin/isovitexin, present in various OPL extracts. Several validation parameters were assessed, resulting in the UHPLC-UV/PDA technique offering good specificity, linearity, accuracy, precision, and robustness, where the values were within acceptable limits. Subsequently, the validated method was employed to quantify luteolin and apigenin derivatives from OPL subjected to different drying treatments and extraction with various solvent systems, giving total luteolin (TLC) and apigenin content (TAC) in the range of 2.04–56.30 and 1.84–160.38 µg/mg extract, respectively. Additionally, partial least square (PLS) analysis disclosed the combination of freeze dry-aqueous methanol yielded OPL extracts with high TLC and TAC, which are strongly correlated with antioxidant activity. Therefore, we provide the first validation report of the UHPLC-UV/PDA method for quantification of luteolin and apigenin derivatives present in various OPL extracts, suggesting that this approach could be employed in standardized herbal preparations by adopting orientin, isoorientin, vitexin, and isovitexin as chemical markers. Full article

(This article belongs to the Special Issue Method Development of Sampling Preparation Techniques)

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15 pages, 1875 KiB

Open AccessArticle

Microwave-Assisted Extraction and HPLC-UV-CD Determination of (S)-usnic Acid in Cladonia foliacea

by Valeria Cavalloro, Giorgio Marrubini, Rita Stabile, Daniela Rossi, Pasquale Linciano, Gabriele Gheza, Silvia Assini, Emanuela Martino and Simona Collina

Molecules 2021, 26(2), 455; https://doi.org/10.3390/molecules26020455 - 16 Jan 2021

Cited by 12 | Viewed by 3480

Abstract

During the years, many usnic acid (UA) conjugates have been synthesized to obtain potent endowed with biological properties. Since (S)-UA is less abundant in nature than (R)-enantiomer, it is difficult to source, thus precluding a deeper investigation. Among the lichens producing UA, Cladonia foliacea is a valuable (S)-UA source. In the present work, we report on a rapid HPLC-UV/PAD-CD protocol suitable for the analysis and the identification of the main secondary metabolites present in C. foliacea extract. Best results were achieved using XBridge Phenyl column and acetonitrile and water, which were both added with formic acid as mobile phase in gradient elution. By combining analytical, spectroscopical, and chiroptical analysis, the most abundant analyte was unambiguously identified as (S)-UA. Accordingly, a versatile microwave-assisted extractive (MAE) protocol, assisted by a design of experiment (DoE), to quantitatively recover (S)-UA was set up. The best result in terms of UA extraction yield was obtained using ethanol and heating at 80 °C under microwave irradiation for 5 min. Starting from 100 g of dried C. foliacea, 420 mg of (S)-UA were achieved. Thus, our extraction method resulted in a suitable protocol to produce (S)-UA from C. foliacea for biological and pharmaceutical investigation or commercial purposes. Full article

(This article belongs to the Special Issue Method Development of Sampling Preparation Techniques)

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20 pages, 4796 KiB

Open AccessReview

Sample Preparation and Diagnostic Methods for a Variety of Settings: A Comprehensive Review

by Zach E. Nichols and Chris D. Geddes

Molecules 2021, 26(18), 5666; https://doi.org/10.3390/molecules26185666 - 18 Sep 2021

Cited by 14 | Viewed by 6544

Abstract

Sample preparation is an essential step for nearly every type of biochemical analysis in use today. Among the most important of these analyses is the diagnosis of diseases, since their treatment may rely greatly on time and, in the case of infectious diseases, containing their spread within a population to prevent outbreaks. To address this, many different methods have been developed for use in the wide variety of settings for which they are needed. In this work, we have reviewed the literature and report on a broad range of methods that have been developed in recent years and their applications to point-of-care (POC), high-throughput screening, and low-resource and traditional clinical settings for diagnosis, including some of those that were developed in response to the coronavirus disease 2019 (COVID-19) pandemic. In addition to covering alternative approaches and improvements to traditional sample preparation techniques such as extractions and separations, techniques that have been developed with focuses on integration with smart devices, laboratory automation, and biosensors are also discussed. Full article

(This article belongs to the Special Issue Method Development of Sampling Preparation Techniques)

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