Development Of Sample Preparation Techniques Research Articles

Advances in sample preparation and HPLC-MS/MS methods for determining amyloid-β peptide in biological samples: a review.

Alzheimer's disease (AD), a neurological disorder, is a major public health concern and the most common form of dementia. Its typical symptoms include memory loss, confusion, changes in personality, and cognitive impairment, which result in patients gradually losing independence. Over the last decades, some studies have focused on searching for effective biomarkers as early diagnostic indicators of AD. Amyloid-β (Aβ) peptides have been consolidated as reliable AD biomarkers and have been incorporated into modern diagnostic research criteria. However, quantitative analysis of Aβ peptides in biological samples remains a challenge because both the sample and the physical-chemical properties of these peptides are complex. During clinical routine, Aβ peptides are measured in the cerebrospinal fluid by immunoassays, but the availability of a specific antibody is critical-in some cases, an antibody may not exist, or its specificity may be inadequate, leading to low sensitivity and false results. HPLC-MS/MS has been reported as a sensitive and selective method for determining different fragments of Aβ peptides in biological samples simultaneously. Developments in sample preparation techniques (preconcentration platforms) such as immunoprecipitation, 96-well plate SPME,onlineSPME, andfiber-in-tubeSPME have enabled not only effective enrichment of Aβ peptides present at trace levels in biological samples, but also efficient exclusion of interferents from the sample matrix (sample cleanup). This high extraction efficiency has provided MS platforms with higher sensitivity. Recently, methods affording LLOQ values as low as 5pgmL-1 have been reported. Such low LLOQ values are adequate for quantifying Aβ peptides in complex matrixes including cerebrospinal fluid (CSF) and plasma samples. This review summarizes the advances in mass spectrometry (MS)-based methods for quantifying Aβ peptides and covers the period 1992-2022. Important considerations regarding the development of the HPLC-MS/MS method such as the sample preparation step, optimization of the HPLC-MS/MS parameters, and matrix effects are described. Clinical applications, difficulties related to analysis of plasma samples, and future trends of these MS/MS-based methods are also discussed.

THE VALIDATION OF THE METHOD FOR QUINOLONES RESIDUES DETERMINATION IN SAMPLES OF MILK, EGG POWDER, TISSUES, BLOOD PLASMA OF ANIMALS USING THE METHOD OF ENZYME-LINKED IMMUNOSORBENT ASSAY

The article presents the results of validation of screening method for the determination of quinolone antibiotics residues (enrofloxacin, ciprofloxacin, marbofloxacin, danofloxacin) in tissue samples, egg powder, milk and blood plasma using RIDASCREEN®Chinolone/Quinolones test kits from R-Biopharm (Germany). According to the information provided by the manufacturer of the kit, the quantitative determination of quinolones content of can be carried out in the following matrices: shrimp, fish, eggs, meat. In accordance with European Commission Decision 2002/657/EC, the methods proposed by the manufacturer were validated taking into account the maximum permissible levels (MRLs), and the results of the development of sample preparation techniques for the assay of liver, milk and blood plasma for various representatives of antibiotics of quinolone group and the corresponding validation results were presented.
 The suitability of the technique was confirmed on the basis of establishing of main validation parameters for screening methods (technical threshold and cut-off factor) using control (blank) samples (muscle and parenchymal tissues of poultry and animals, cow’s milk, blood plasma of broiler chickens and egg powder) and spiked with quinolones standard solutions at the level of ½ MRL according to the "added-found" criterion. The main advantages of the developed method are the simplicity of performance, rapidity and economic efficiency.
 The reliability of the results obtained by the developed method was verified using confirmatory UPLC-MS/MS method. The results of comparative study of control (blank) samples of chicken muscle tissues, egg powder and cow’s milk and spiked with enrofloxacin standard solution at the level of 2.5 and 5.0 μg/kg are presented.
 The proposed methods for liver, milk and blood plasma sample preparation can be used to study withdrawal periods and bioequivalence of veterinary drugs based on quinolone antibiotics.

Forensic Entomotoxicology: A Brief Look at Sample Preparation Techniques – A Review

Forensic entomotoxicology is a relatively new science whose applications aims the detection of toxic substances through a matrix of necrophagous insects in a crime scene. In addition, it aims the investigation of the impacts of the xenobiotics on these insects, generating impacts in the measurement of the post-mortem interval (PMI). Calliphoridae larvae, the most important insect for forensic entomology, has an average amount of 25% of crude fat and 53% of crude protein, being a complex matrix that requires some sample preparation methodology before inserting the sample in some equipment to perform the chemical instrumental analysis. Sample preparation methods should be applied in order to increase the protection of analytical equipment from impurities present in the arthropod matrix, as well as increase the detectability of the test analyte by the analytical instrumentation of choice. Thus, the objective of the present work is to compile sample preparation techniques since traditional procedures until new approaches found in the scientific literature applied for entomotoxicological analysis in Calliphoridae specimens and respective analytes. It was observed the lack of a complete standardization for entomotoxicological approach, mainly for traditional extractions preparations. In this sense, microextraction-based techniques become an even greater challenge for arthropod–like matrix, especially in specimens from Calliphoridae family for xenobiotics determination. So, the development of sample preparation techniques with more sustainable approaches, such as reduced use of solvents, added to the increase of the powerfulness of analytical instrumental techniques should be encourage in order to improve the forensic entomotoxicology approach.

Novel Applications of Microextraction Techniques Focused on Biological and Forensic Analyses

In recent years, major attention has been focused on microextraction procedures that allow high recovery of target analytes, regardless of the complexity of the sample matrices. The most used techniques included liquid-liquid extraction (LLE), solid-phase extraction (SPE), solid-phase microextraction (SPME), dispersive liquid-liquid microextraction (DLLME), microextraction by packed sorbent (MEPS), and fabric-phase sorptive extraction (FPSE). These techniques manifest a rapid development of sample preparation techniques in different fields, such as biological, environmental, food sciences, natural products, forensic medicine, and toxicology. In the biological and forensic fields, where a wide variety of drugs with different chemical properties are analyzed, the sample preparation is required to make the sample suitable for the instrumental analysis, which often includes gas chromatography (GC) and liquid chromatography (LC) coupled with mass detectors or tandem mass detectors (MS/MS). In this review, we have focused our attention on the biological and forensic application of these innovative procedures, highlighting the major advantages and results that have been accomplished in laboratory and clinical practice.

Utilizing imaging mass spectrometry to analyze microbial biofilm chemical responses to exogenous compounds.

Matrix-assisted laser desorption/ionization imaging mass spectrometry (MALDI-IMS) is an appealing label-free method for imaging biological samples which focuses on the spatial distribution of chemical signals. This approach has been used to study the chemical ecology of microbes and can be applied to study the chemical responses of microbes to treatment with exogenous compounds. Specific conjugated cholic acids such as taurocholic acid (TCA), have been shown to inhibit biofilm formation in the enteric pathogen Vibrio cholerae and MALDI-IMS can be used to directly observe the chemical responses of V. cholerae biofilm colonies to treatment with TCA. A major challenge of MALDI-IMS is optimizing the sample preparation and drying for a particular growth condition and microbial strain. Here we demonstrate how V. cholerae is cultured and prepared for MALDI-IMS analysis and highlight critical steps to ensure proper sample adherence to a MALDI target plate and maintain spatial distributions when applying this technique to any microbial strain. We additionally show how to use both manual interrogation and statistical analyses of MALDI-IMS data to establish the adequacy of the sample preparation protocol. This protocol can serve as a guideline for the development of sample preparation techniques and the acquisition of high quality MALDI-IMS data.

Recent advance of new sample preparation materials in the analysis and detection of environmental pollutants

针对复杂样品的分析和痕量目标物的检测,样品前处理是必不可少的,高效的样品前处理技术不仅可以去除或减小样品基质干扰而且能够实现分析物的富集,提高分析检测的准确性和灵敏度。近年来,固相萃取、磁分散固相萃取、枪头固相萃取、搅拌棒萃取、固相微萃取等高效的样品前处理技术已在环境污染物分析检测中获得广泛关注,萃取效率主要取决于萃取材料,所以新型的高效萃取材料一直是样品前处理研究领域的重要发展方向。该文总结和讨论了近年来新型样品前处理材料在环境污染物分析检测中的研究进展,主要聚焦在石墨烯、氧化石墨烯、碳纳米管、无机气凝胶、有机气凝胶、三嗪基功能材料、三嗪基聚合物、分子印迹聚合物、共价有机框架材料、金属有机框架材料以及它们的功能化萃取材料等。这些材料已经被应用于环境样品中不同类别污染物的萃取富集,如重金属离子、多环芳烃、塑化剂、烷烃、苯酚、氯酚、氯苯、多溴联苯醚、全氟磺酸、全氟羧酸、雌激素、药物残留、农药残留等。这些样品前处理材料具有高的表面积、大量的吸附位点,并涉及多种萃取机理如π-π、静电、疏水、亲水、氢键、卤键等相互作用。基于这些萃取材料的多种样品前处理技术与各类检测方法如色谱、质谱、原子吸收光谱、荧光光谱、离子迁移谱等相结合,已广泛应用于环境污染物的高灵敏分析检测。最后,该文总结了样品前处理发展中存在的问题,并展望了其未来在环境分析中的发展趋势。

Application of magnetic nanomaterials in bioanalysis

The importance of magnetic nanomaterials and magnetic hybrid materials, which are classified as new generation materials, in analytical applications is increasingly understood, and research on the adaptation of these materials to analytical methods has gained momentum. Development of sample preparation techniques and sensor systems using magnetic nanomaterials for the analysis of inorganic, organic and biomolecules in biological samples, which are among the samples that analytical chemists work on most, are among the priority issues. Therefore in this review, we focused on the use of magnetic nanomaterials for the bioanalytical applications including inorganic and organic species and biomolecules in different biological samples such as primarily blood, serum, plasma, tissue extracts, urine and milk. We summarized recent progresses, prevailing techniques, applied formats, and future trends in sample preparation-analysis methods and sensors based on magnetic nanomaterials (Mag-NMs). First, we provided a brief introduction of magnetic nanomaterials, especially their magnetic properties that can be utilized for bioanalytical applications. Second, we discussed the synthesis of these Mag-NMs. Third, we reviewed recent advances in bioanalytical applications of the Mag-NMs in different formats. Finally, recently literature studies on the relevance of Mag-NMs for bioanalysis applications were presented.

Recent advances in sample preparation techniques for the lipid profiling based on chromatography-mass spectrometry

As the main structural components of cellular and sub-cellular membranes, lipids are a major source of energy and play an important role in various biological processes such as cellular signaling. Lipid profiling has attracted increasing attention in recent years, and chromatography-mass spectrometry techniques for lipid profiling occupy a dominant position in this regard. Sample preparation, which aims at enriching trace substances and reducing matrix interferences, is a crucial step in the analysis of lipids for the intricacy of sample matrices. Here, we review recent developments in sample preparation techniques based on chromatography-mass spectrometry and their application to lipid profiling. Various sample preparation techniques are described and summarized. The extraction methods based on liquid phase included liquid-liquid extraction and single organic solvent extraction. The extraction methods based on solid phase involved solid-phase extraction and solid-phase microextraction. The field-assisted extraction methods cover supercritical fluid extraction, pressurized liquid extraction, microwave-assisted extraction, and ultrasound-assisted extraction. Moreover, online coupling sample preparation methods and sample preparation methods for in vivo lipid analysis are presented. Finally, the problems and trends in sample preparation techniques for lipid profiling based on chromatography-mass spectrometry are discussed. It is believed that efficient development of sample preparation techniques would help improve the sensitivity and selectivity of lipid profiling as well as the analysis speed.

Recent advances in sample preparation techniques in China.

Sample preparation is the procedure before instrumental analysis and significant to its effectiveness and efficiency. However, this procedure is usually time-consuming, labor intensive, and prone to error. In the last decade, the development of sample preparation techniques has received increasing attention, especially in complex sample application. To pretreat samples faster and more effectively, advanced materials, instrumentation, and methods have been combined with typical techniques, including extraction, membrane separation, and chemical conversion techniques. Researchers in China focused on the development of simple, efficient sample preparation methods with selective enrichment and rapid separation capabilities for target analysis in complicated sample matrix and contribute almost a half of the publications in this specific field. In this review, a panorama of sample preparation techniques in China has been composed from more than 140 references, and we highlight some promising methods developed during recent years and introduce different separation materials with respect to these methods.

Use of solid phase extraction for the determination of additives in automotive oils using the GC / MS

Currently, the determination of additives in lubricating oils is carried out using such analysis methods as IR spectroscopy, TLC, HPLC-UV, GC, GC-MS. To eliminate the interfering influence of the base oil components, various sample preparation methods are used, which are often not suitable for isolating a wide range of additives, are poorly reproduced, or are completely absent. In this regard, the urgent problem is the development of sample preparation techniques that can effectively isolate various additives for subsequent analysis. This paper presents a methodology for determining additives for the subsequent identification of automotive lubricating oils (MO). The method includes sample preparation by the method of solid phase extraction (SPE) with subsequent analysis by GC / MS. The optimal conditions for obtaining a characteristic and reproducible additives profile were determined: silica gel drying temperature, analyte elution rate, composition of the elution mixture, volumes of washing liquid and eluent. This method of SPE allows to isolate a wide range of additives: sterically hindered phenols, alkyl diphenylamines, dialkyldithiophosphates of zinc, alkyl salicylates, alkyl phenolates and components of extreme pressure additives. Also reduced the number of stages of the procedure SPE was compared with known methods. Keywords : lubricating oils, additives, solid-phase extraction, gas-liquid chromatography / mass spectrometry, GC/MS (Russian) DOI: http://dx.doi.org/10.15826/analitika.2019.23.4.001 R.L. Akhmedov 1 , S.S. Kravtsova 1 , K.A . Dychko 1 , I.V. Ramus’ 2 1 Tomsk State University, Lenin Ave, 36, Tomsk, 634050, Russian Federation 2 EFC DMIA of Russia in Tomsk region, Vershinina st, 17/1, Tomsk, 634041, Russian Federation

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.

Development of sample preparation technique to characterize chemical structure of humin by synchrotron‐radiation–based X‐ray photoelectron spectroscopy

Carbon‐binding state of humin (HM, a non‐conductive insoluble organo‐mineral humic substance) was successfully characterized for the first time by synchrotron‐radiation–based X‐ray photoelectron spectroscopy (XPS). Four sample preparation techniques—HM on double‐sided carbon tape, indium sheet, copper mesh, and in pellet formed from the mixture of HM and copper powder (Cu) at different mixing ratios (1:1, 1:2, and 1:6 v/v)—were compared. The results show that HM samples prepared using the first three methods had significant charge buildup, which made the interpretation of the XPS spectra impossible because of the shifts in the binding energy of C 1s XPS spectra. Pellets of HM:Cu mixture enhanced the electrical conductivity and reduced charge buildup on the sample surface. Pellets prepared with HM:Cu ratio of 1:1 (v/v) provided the minimum charge buildup and high sensitivity with difference in C 1s spectra regardless of the observing position. The C 1s spectra, estimated by the subtraction of the carbon contamination in Cu, showed the resolution of CC (284.0 eV), CC/CH (285.1 eV), CO (286.3 eV), CO (287.3 eV), and OCO (288.3 eV) and three additional peaks of CF (289.3 eV), CF2 (290.2 eV), and CF3 (291.4 eV). Soft X‐ray absorption spectroscopic (XAS) analysis further proved the existence of fluoride (F 1s) in HM structure. The detection of fluorinated carbon in HM showed a great advancement of XPS compared with other conventional analyses. X‐ray with the incident angle of 0° provided the smallest (nearly negligible) energy shift in the C 1s spectra of HM and did not damage the surface of the sample.

Multiscale Characterization of N-Functionalized Carbon-Based Catalysts and Supports

Nitrogen-functionalized carbon-based materials are an intriguing class of materials finding utility in many energy and environmental applications [1]. These materials have been explored as alternatives to conventional carbon supports for precious and non-precious catalysts in polymer electrolyte fuel cells (PEMFCs), demonstrating improvements in catalyst-support interactions resulting in enhanced activity and stability. Incorporation of atomically-dispersed transition metal into the network of nitrogen-doped carbon leads to significant enhancement in activity of nitrogen sites producing one of the most promising classes of platinum group metal-free (PGM-free) catalysts for oxygen reduction reaction (ORR) at the cathode of the PEMFCs [2]. These catalysts have shown significant improvements in activities over the past decade, offering opportunity to reduce the cost of PEMFCs, eliminate reliance on scarce elements, and motivating further studies to improve their activity, active site density, and stability. Since current synthetic methods are not capable of producing a perfectly homogeneous material with only one dopant configuration, this work aims to better understand the heterogeneities present in N-doped carbons (N-Cs) and PGM-free catalysts based on iron, nitrogen and carbon (Fe-N-Cs) by combining synthesis efforts with multi-technique characterization. High surface area N-C nanospheres are synthesized by a two-step process of solvothermal treatment followed by pyrolysis. A solvothermally treated, aqueous alcohol solution of resorcinol, formaldehyde, and ethylenediamine is pyrolyzed to produce porous carbon nanospheres which contain a diverse set of nitrogen sites [3]. The amount of ethylenediamine added to the solution and the temperature of pyrolysis are modified in order to produce nanospheres with controlled size and relevant compositions. Iron is integrated into the carbon using various iron precursors, either during or after carbon synthesis [4]. Similar to the N-C spheres, alterations in this synthesis allow for a diverse array of materials with different prominent active sites. Initial assessment of a two-dimensional morphology of these materials is made using transmission electron microscopy (TEM) and elemental distributions are acquired with energy dispersive x-ray spectroscopy (EDS). Three-dimensional, atomic distribution of the species, demonstrating differences between surface and bulk are studied with atom probe tomography (APT). Since APT analysis of carbon materials is not developed yet, this work focuses on both, development of sample preparation techniques using a focused ion beam (FIB) to produce specimens with appropriate dimensions and APT data analysis to generate reconstructions of such soft materials such as these N-C and Fe-N-C spheres. Integration of 2D and 3D data at multiple scales provides a pathway to better understand these complex materials and to maximize active site density for higher efficiency of these materials in various electrocatalytic reactions. Figure 1. a) STEM image of several N-C spheres, b) EDS map showing elemental distribution of N (green) and C (red) across the spheres. Wood, K. N., O’Hayre, R., and Pylypenko, S. Energy Environ. Sci. 7, 1212 (2014).Jaouen, F., Proietti, E., Lefèvre, M., Chenitz, R., Dodelet, J.P., Wu, G., Chung, H.T., Johnston, C.M., and Zelenay, P., Energy Environ. Sci. 4, 114 (2011).Wickramaratne, N. P., Xu, J., Wang, M., Zhu, L., Dai, L., and Jaroniec, M. Chemistry of Materials 26, 2820 (2014).Pylypenko, S., Borisevich, A., More, K.L., Corpuz, A.R.., Holme, T., Dameron, A.A., Olson, T.S., Dinh, H.N., Gennett, T., and O' Hayre, R. Energy Environ. Sci. 6, 2957 (2013). Figure 1

Imaging of wood tissue by ToF-SIMS: Critical evaluation and development of sample preparation techniques

Tissue of Norway spruce wood was investigated by time-of-flight secondary-ion mass spectrometry (ToF-SIMS) and field-emission scanning electron microscopy (FE-SEM). Different sample preparation techniques (including sectioning and drying) traditionally used for SEM analysis were compared and critically evaluated. A high contamination of wood surfaces by polytetrafluoroethylene (PTFE) introduced onto the sample during sectioning was detected by ToF-SIMS. A new protocol was developed and images of wood sections dried in different ways were compared. Main location of Mg, Na, K and Ca, but no lignin in membranes of bordered pits in spruce section surfaces was detected by ToF-SIMS imaging if critical point drying (CPD) or acetone extraction followed by drying under nitrogen flow (AEND) was applied. No specific locations of wood components as well as low signals from metal ions (Mg and Na) were observed on the wood surfaces of freeze-dried (FD) or air-dried (AD) sections. It was found that extractive substances, presenting on surfaces of FD and AD wood section, were evenly distributed on the surfaces and interfered with ToF-SIMS analysis. Our results indicated that ToF-SIMS imaging was critically sensitive to the sample preparation technique and a strict protocol for characterization of metals, lignin and polysaccharides in wood was suggested.

A review of focused ion beam technology and its applications in transmission electron microscopy

The role of focused ion beam (FIB) fabrication in the development of sample preparation techniques for transmission electron microscopy (TEM) has been described in this paper. Since the repeatability of FIB sampling and TEM observations has become important, the microsampling and in situ lift-out methods are currently in wide use. Furthermore, artifacts induced during FIB milling and the consequent difficulties with energy dispersive X-ray spectroscopy are detailed. The remarkably increased capability of scanning ion microscopy and its applications are also discussed.

鋼中微量成分分析のための試料前処理技術

鋼中微量成分分析のための試料前処理技術

Transmission electron microscopy of semiconductor devices

The search for further miniaturization in the semiconductor industry has resulted in the reduction in the dimensions of devices to a size which can no longer be effectively seen by the conventional methods of light microscopy. The use of both transmission and scanning electron microscopy in the field of silicon device characterization has now become an essential ingredient of the design and manufacture of new technologies. It is often the only way in which a device designer can know for certain whether the manufacturing process is producing the required structure. Cross-sectional TEM has therefore become an integral part of both quality control and development.One of the most important areas which resulted in the increased importance of TEM in the semiconductor device field was the development of sample preparation techniques which enable cross-sections through layers of widely differing compositions that are found in the devices structures.