Sample Preparation Techniques Research Articles

Bubble‐Assisted Sample Preparation Techniques for Mass Spectrometry

ABSTRACTThis review delves into the efficacy of utilizing bubbles to extract analytes into the gas phase, offering a faster and greener alternative to traditional sample preparation methods for mass spectrometry. Generating numerous bubbles in liquids rapidly transfers volatile and surface‐active species to the gas phase. Recently, effervescence has found application in chemical laboratories for swiftly extracting volatile organic compounds, facilitating instantaneous analysis. In the so‐called fizzy extraction, liquid matrices are pressurized with gas and then subjected to sudden decompression to induce effervescence. Alternatively, specifically designed effervescent tablets are introduced into the liquid samples. In situ bubble generation has also enhanced dispersion of extractant in microextraction techniques. Furthermore, droplets from bursting bubbles are collected to analyze non‐volatile species. Various methods exist to induce bubbling for sample preparation. The polydispersity of generated bubbles and the limited control of bubble size pose critical challenges in the stability of the bubble–liquid interface and the ability to quantify analytes using bubble‐based sample preparation techniques. This review covers different bubble‐assisted sample preparation methods and gives practical guidance on their implementation in mass spectrometry workflows. Traditional, offline, and online approaches for sample preparation relying on bubbles are discussed. Unconventional bubbling techniques for sample preparation are also covered.

Experimental determination of the coefficient of viscosity of the dry snow

Snow compaction is a natural process in the evolution of any snow cover, and this obviously changes the physical and mechanical properties of a snow thickness. The quantitative estimate of this process is a coefficient of the snow viscosity, which is linearly related to the rate of the snow cover deformation The technique for preparation and testing of samples with the fine-grain snow under condition of uniaxial compression at negative temperatures is described. It was determined that values of the snow viscosity coefficient fall within the range from 0.10 to 0.30 g/cm³ for three temperature intervals. The viscosity coefficient of the fine-grain snow varies from 10⁸ до 10¹⁰ Па. The data obtained made possible to find the limits of variability of this coefficient for winter conditions on the Russian plain. A dependence of the viscosity coefficient on the snow density and temperature is proposed, and it describes the series of the above shown experimental data. It is shown that influence of changes in the viscosity coefficient of fine-grain snow on the snow properties depending on its density are comparable in scale to the influence of the temperature. The result may be useful for modeling the evolution of snow cover.

Endochondral ossification: insights into the cartilage mineralization processes achieved by an anhydrous freeze substitution protocol

Growth plate cartilage (GP) serves as a dynamic site of active mineralization and offers a unique opportunity to investigate the cell-regulated matrix mineralization process. Transmission electron microscopy (TEM) provides a means for the direct observation of these mechanisms, offering the necessary resolution and chemical analysis capabilities. However, as mineral crystallinity is prone to artifacts using aqueous fixation protocols, sample preparation techniques are critical to preserve the mineralized tissue in its native form. We optimized cryofixation by high-pressure freezing followed by freeze substitution in anhydrous acetone containing 0.5% uranyl acetate to prepare murine GP for TEM analysis. This sample preparation workflow maintains cellular and extracellular protein structural integrity with sufficient contrast for observation and without compromising mineral crystallinity. By employing appropriate sample preparation techniques, we were able to observe two parallel mineralization processes driven by chondrocytes: 1) intracellular- and 2) extracellular-originating mineralized vesicles. Both mechanisms are based on sequestering calcium phosphate (CaP) within a membrane-limited structure, albeit originating from different compartments of the chondrocytes. In the intracellular originating pathway, CaP accumulates within mitochondria as globular CaP granules, which are incorporated into intracellular vesicles (500-1000 nm) and transported as granules to the extracellular matrix (ECM). In contrast, membrane budding vesicles with a size of approximately 100-200nm, filled with needle-shaped minerals were observed only in the ECM. Both processes transport CaP to the collagenous matrix via vesicles, they can be differentiated based on the vesicle size and mineral morphologies. Their individual importance to the cartilage mineralization process is yet to be determined. Statement of SignificanceWe do not fully understand the process by which epiphyseal cartilage mineralizes - a vital step in endochondral bone formation. Previous work has proposed that mitochondria and intracellular vesicles are storage sites for the delivery of mineral to collagen fibrils. However, these concepts are founded on results from in vitro models of mineralization; no prior work has observed mineral-containing intracellular vesicles or mitochondria in developing epiphyseal cartilage. Here we developed a new cryofixation preparation route for transmission electron microscopy (TEM) imaging that has disclosed a cell-regulated process of mineralization in epiphyseal cartilage. High resolution TEM images revealed an involvement of mitochondria and intracellular and extracellular vesicles in delivering transient mineral phases to the collagen fibrils to promote cartilage mineralization.

Computational and experimental investigation on functional monomer selection for a novel molecularly imprinting polymer of remdesivir

Molecularly-imprinted polymers (MIPs) are a sample preparation technique with a functional cavity that can rebind the same or similar analyte to the template. It also can increase the selectivity of the analytical method. Computational approaches are capable of making predictions about the most optimal synthesis conditions, including the most appropriate monomers and solvents. This study used the DFT method, GFN2-xTB, and molecular dynamics simulation to predict MIP synthesis’s best functional monomer, solvent, and stoichiometric ratio. Remdesivir (RMD), used as a template, has also never been developed to be made as MIP. The monomers were acrylic acid (AA), 2-hydroxyethyl methacrylate (HEMA), and acrylamide (AM). Laboratory testing, association constant, and Job plot analysis are carried out to confirm the results of computational tests. The polymer was synthesized using precipitation and characterized using SEM, FTIR, and TGA. The adsorption capacity was evaluated in two different solvents, i.e. acetonitrile (ACN) and water: ACN=9: 1 (v/v). Computational study results identified acrylamide as the most interactive ligand with RMD as a template. The results of molecular dynamics simulations identify that the RMD: AM=1: 1 complex is the most stable in terms of the radial distribution function, hydrogen bond occupancy, and Gibbs bond free energy. The adsorption ability test results show that MIP 1 and MIP 2 have imprinting factor values of 1.36 and 1.15, respectively.

Ionic liquids-based adsorbents for extraction and separation: A review emphasizing recent advances in sample preparation

Ionic liquids (ILs) exhibit remarkable physical and chemical properties, encompassing negligible vapor pressure, non-flammability, high thermal stability and mechanical robustness. Moreover, ILs can be readily tailored for specific functions by altering the combination of cations and anions. These unique attributes have led to the widespread adoption of ILs as highly efficient adsorbents in sample preparation. To meet the requirements of various applications, ILs are often immobilized or functionalized. This review summarizes the primary types of currently available ILs-based adsorbents, including poly(ionic liquids), ILs-modified silica-based adsorbents, ILs-modified carbon-based adsorbents, ILs@metal–organic frameworks composite adsorbents, and ILs@covalent organic frameworks composite adsorbents. Additionally, the applications of ILs-based adsorbents in sample preparation techniques such as dispersive liquid-liquid microextraction, single-drop microextraction, hollow fiber liquid-phase microextraction, solid-phase extraction, magnetic solid-phase extraction, and solid-phase microextraction are introduced. Furthermore, the review provides insights into the challenges and prospects for the future development of ILs-based adsorbents.

On-site extraction of phenoxycarboxylic acid herbicides in environmental waters utilizing monolith-based in-tip microextraction technique

On-site extraction plays a significant role in the reliable quantification of strong polar phenoxycarboxylic acid herbicides (PCAs) in aqueous samples. In current study, a new technique for the field sample preparation of PCAs was developed by means of three channels in-tip microextraction device (TCIM). To capture PCAs effectively, an extraction phase based on monolith (EPM) using vinylimidazole and divinylbenzene/ethylene dimethacrylate as monomer and cross-linkers, respectively, was in-situ synthesized in pipette tips. The EPM fabricated at optimal conditions were characterized by a series of techniques and employed as the adsorbent of TCIM for the on-site extraction of PCAs. The adsorption isotherm was studied so as to inspect the extraction behaviors of EPM towards PCAs. Results revealed that the proposed EPM/TCIM presented satisfactory extraction performance towards PCAs through multiple interactions. The enrichment factors and adsorption capacity were 74-277 and 20 mg/g, respectively. Under the most beneficial extraction parameters, the developed EPM/TCIM was successfully employed to on-site extract PCAs, and then combining with HPLC equipped with diode array detector to monitor trace PCAs in actual waters. The limits of detection (LODs) towards investigated PCAs varied from 0.071 μg/L to 0.30 μg/L. In addition, the accuracy of established approach was inspected with documented method. Compared with existing lab-based sample preparation approaches, the introduced field sample preparation technique exhibits some merits such as avoidance of transporting large volume of water, prevention of analytes loss during sampling procedure, less usage of organic solvent and achievement of satisfactory efficient in sample preparation.

Accuracy of various matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS)-based rapid identification methods—As a tool to augment diagnostic stewardship in blood culture laboratory, South India

BackgroundBlood stream infection is a medical emergency associated with high morbidity and mortality. Prompt identification of bloodstream infection-causing microorganisms directly from positive blood culture will significantly enhance patient care by reducing the turnaround time of pathogen recognition. MethodsA total of 256 freshly flagged positive blood culture bottles were subjected to Gram staining. Direct MALDI-TOF MS analysis was performed following sample preparation techniques such as lysis centrifugation, lysis filtration and VITEK® MS BC kit to directly identify microorganisms from positive blood cultures. Along with these short-term incubation methods of Choco spot and minute colony(8–10h) were also performed. All those positive bottles were identified by the routine (reference) laboratory method. Results177 isolates (69.14 %) were correctly identified by Lysis centrifugation, 163 isolates (63.67 %) were correctly identified by Lysis filtration, 206 isolates (80.47 %) were correctly identified by Choco spot,250 isolates (97.65 %) were correctly identified from minute colony (8–10h) of incubation. Of 162 isolates,115 isolates (70.99 %) were correctly identified by VITEK® MS Blood culture kit, (BioMérieux). VITEK® MS BC kit method revealed higher agreement with the kappa value of 0.697 than lysis centrifugation (0.672) followed by lysis filtration (0.611). ConclusionsIn house method of lysis centrifugation is found to be equivalent to VITEK® MS BC kit method and superior to lysis filtration method in correct direct identification of bacteria from positive blood cultures by MALDI-TOF MS analysis. As lysis centrifugation requires only 10 min of processing time as compared to overnight incubation, thus it offers a less expensive substitute for the VITEK® MS BC kit in the clinical laboratory. As a consequence of this study, we have implemented direct MALDI-TOF-based identification from positive BCs in our daily routine diagnostic management.

Assessment of greenness for solid phase microextraction techniques of sample preparation for flavors by AGREE Prep & SPMS tools

Assessing the greenness of sample preparation techniques is essential due to the use of various solvents, chemicals, reagents, sorbents, pH adjustments, and energetic inputs. Solid-Phase Microextraction (SPME) is preferred over traditional flavor extraction methods such as Simultaneous Distillation Extraction (SDE) and Solvent-Assisted Flavor Evaporation (SAFE) because of its sensitivity, efficiency, speed, versatility, and economy. SPME fibers coated with stationary phases can extract volatile and semi-volatile flavor compounds from food samples, which are then desorbed and analyzed by Gas Chromatography-Mass Spectrometry (GC–MS). This article provides an assessment of the greenness of 50 SPME techniques for flavor analysis using the AGREE Prep and Sample Preparation Metric of Sustainability (SPMS) tools. This evaluation offers valuable insights into the environmental impact and sustainability of SPME as sample preparation techniques for flavour analysis. As per AGREE Prep, method 34 was found to be environmental friendly with score of 0.66, attributed to safe solvents, minimized waste, high sample throughput, and low energy consumption where as method 7 with SPMS scores of 7.05 is more sustainable due to miniaturization, fewer steps, and low energy use.

Online restricted access molecularly imprinted solid phase extraction coupled with electrospray ionization-tandem mass spectrometry for determination of mebendazole and albendazole in milk samples

Multifunctional materials, such as restricted access molecularly imprinted polymers covered with bovine serum albumin (RAMIP-BSA), are effective alternatives for sample preparation techniques. This material selectively adsorbs analytes while excluding macromolecules, enhancing the analysis's efficiency. Among analytical techniques, ESI-MS/MS (Electrospray Ionization-Tandem Mass Spectrometry) has successfully identified and quantified various molecules, including trace-level drugs. Therefore, we proposed, for the first time, an integrated online extraction/analysis system that combines the benefits of RAMIP-BSA and ESI-MS/MS for analyzing mebendazole (MBZ) and albendazole (ABZ) in milk samples without the need for chromatographic separation. Initially, a RAMIP selective for MBZ was synthesized using the bulk method with methacrylic acid and glycidyl methacrylate. Then, the polymer was covered with bovine serum albumin. Subsequently, this adsorbent was packed in a small column and coupled with an ESI-MS/MS instrument in an online configuration. Milli-Q water was used as the loading and reconditioning mobile phases, and a solution of formic acid in methanol (1:100 v/v) was employed as the elution phase. The system enabled simultaneous extraction and determination of MBZ and ABZ in milk samples. The method exhibited linearity between 15.0 and 125.0 μg L−1 for MBZ and 10.0 and 125.0 μg L−1 for ABZ (with a correlation coefficient exceeding 0.99). The limits of quantification were 15.0 and 10.0 μg L−1 for MBZ and ABZ, respectively. Good precision and accuracy were achieved. The developed method was used to analyze MBZ and ABZ in real milk samples and proved to be a viable alternative to conventional sample preparation and chromatographic techniques.

Application of salt-assisted liquid extraction in bioanalytical methods

This review provides a comprehensive analysis of bioanalytical methods employed for the quantification of drug molecules in various biological matrices, including human plasma, urine, breast milk, and mouse plasma. The study not only examines traditional sample preparation techniques such as protein precipitation (PP), liquid-liquid extraction (LLE), and solid-phase extraction (SPE), but also delves into the relatively new and innovative salting-assisted liquid-liquid extraction (SALLE). It offers a thorough comparison of analytical methods utilizing SALLE, focusing on key parameters such as analysis time, calibration range, and the type and quantity of salts and organic solvents used. This review aims to serve as an essential resource for researchers and practitioners in selecting the most suitable bioanalytical methods for pharmacokinetic studies and drug monitoring, ultimately enhancing data quality and analytical efficiency in both clinical and research settings.

The Addition of Transcriptomics to the Bead-Enabled Accelerated Monophasic Multi-Omics Method: A Step toward Universal Sample Preparation.

Omics-based measurements enable the study of biomolecules in a high-throughput fashion, leading to the characterization and quantification of biological systems. Multi-omics methods aim to incorporate several omics measurements for a more holistic approach, which is crucial for advancing our understanding of the diversity and redundancy of biological systems. Current multi-omics sample preparation methods have achieved proteomics, lipidomics, and metabolomics from individual samples; however, the bioinformatic tools currently available for interpreting data generated from these omics are limited. Alternately, transcriptomics has a wide arsenal of available bioinformatic tools offering intensive sample characterization but has yet to be incorporated into a unified, multi-omics sample preparation technique. Herein we describe the modified bead-enabled accelerated monophasic multi-omics (mBAMM) method, which incorporates RNA extraction for transcriptomics analysis. mBAMM was shown to enable RNA-seq without compromising the isolation of biomolecules for proteomics, lipidomics, and metabolomics. This methodology greatly improves sample characterization and represents a major innovation toward cohesive insights into biological systems.

Overview of Liquid Sample Preparation Techniques for Analysis, Using Metal-Organic Frameworks as Sorbents.

The preparation of samples for instrumental analysis is the most essential and time-consuming stage of the entire analytical process; it also has the greatest impact on the analysis results. Concentrating the sample, changing its matrix, and removing interferents are often necessary. Techniques for preparing samples for analysis are constantly being developed and modified to meet new challenges, facilitate work, and enable the determination of analytes in the most comprehensive concentration range possible. This paper focuses on using metal-organic frameworks (MOFs) as sorbents in the most popular techniques for preparing liquid samples for analysis, based on liquid-solid extraction. An increase in interest in MOFs-type materials has been observed for about 20 years, mainly due to their sorption properties, resulting, among others, from the high specific surface area, tunable pore size, and the theoretically wide possibility of their modification. This paper presents certain advantages and disadvantages of the most popular sample preparation techniques based on liquid-solid extraction, the newest trends in the application of MOFs as sorbents in those techniques, and, most importantly, presents the reader with a summary, which a specific technique and MOF for the desired application. To make a tailor-made and well-informed choice as to the extraction technique.

Extraction of synthetic cathinones from biological samples: A systematic review

Analysis of biological samples containing synthetic cathinones has become a significant area of interest for researchers in recent years, because synthetic cathinones can cause adverse reactions such as delusions and hallucinations. Generally, the intricate nature of the sample matrix and exceedingly low drug concentration in biological samples present significant challenges for the determination of target substances. Accordingly, scientists were dedicated to the advancement of effective sample preparation techniques to address these difficulties. However, the current reviews involved in synthetic cathinones all focused on detection methods. A systematic review focusing on sample preparation for the quantification of synthetic cathinones is still lacking. In light of that, this paper reviewed the most commonly used sample preparation techniques for synthetic cathinones. Recent advances in sample preparation techniques for synthetic cathinones in different biological samples such as blood, urine, oral fluid and hair samples were discussed. In addition, we prospected the challenges and the future perspectives of biological sample preparation techniques for synthetic cathinones determination.

Mass spectrometry-based proteomics for source-level attribution after DNA extraction

Biological traces recovered from crime scenes serve as vital evidence in forensic investigations. While DNA evidence is frequently used to address the sub-source level of the hierarchy of propositions, the biological source of the DNA can be highly probative at the source level. Current body fluid detection methods pose certain limitations, such as reports of false positive results from some of the presumptive and/or confirmatory tests in current use. These tests are also individual tests for the detection of one body fluid, meaning that if the sample is suspected to be a mixture of multiple body fluids, then different tests would need to be conducted to confirm the body fluid(s) present, which may exhaust small amounts of available biological trace. Proteomics applications for the identification of body fluids have been previously explored, and potential biomarkers indicative of body fluids discovered from liquid-chromatography tandem mass spectrometry (LC-MS/MS) methods have been reported. This work focuses on developing a mass spectrometry-based proteomics approach for the identification of body fluids by targeting discriminating peptide biomarkers from the non-DNA component left over after DNA extraction of samples. The non-DNA component is typically a waste product but with unappreciated evidential value. Our methodology for the purification of proteins from the post-DNA extraction waste includes an acetone precipitation and single-pot solid-phase-enhanced sample preparation (SP3) technique, microwave-assisted trypsin digestion, and LC-MS/MS analysis of the resultant peptides. Preliminary results from this proof-of-concept study include a list of potentially discriminating proteins and peptides for blood, saliva, and semen developed from the analysis of post-DNA extraction waste. Our method allows for multiple analytes to be targeted simultaneously from a DNA profiling waste stream and we anticipate that it could eventually be incorporated into standard forensic laboratory workflows.

Reshaping Capillary Electrophoresis With State-of-the-Art Sample Preparation Materials: Exploring New Horizons.

Capillary electrophoresis (CE) is a powerful analysis technique with advantages such as high separation efficiency with resolution factors above 1.5, low sample consumption of less than 10µL, cost-effectiveness, and eco-friendliness such as reduced solvent use and lower operational costs. However, CE also faces limitations, including limited detection sensitivity for low-concentration samples and interference from complex biological matrices. Prior to performing CE, it is common to utilize sample preparation procedures such as solid-phase microextraction (SPME) and liquid-phase microextraction (LPME) in order to improve the sensitivity and selectivity of the analysis. Recently, there have been advancements in the development of novel materials that have the potential to greatly enhance the performance of SPME and LPME. This review examines various materials and their uses in microextraction when combined with CE. These materials include carbon nanotubes, covalent organic frameworks, metal-organic frameworks, graphene and its derivatives, molecularly imprinted polymers, layered double hydroxides, ionic liquids, and deep eutectic solvents. The utilization of these innovative materials in extraction methods is being examined. Analyte recoveries and detection limits attained for a range of sample matrices are used to assess their effects on extraction selectivity, sensitivity, and efficiency. Exploring new materials for use in sample preparation techniques is important as it enables researchers to address current limitations of CE. The development of novel materials has the potential to greatly enhance extraction selectivity, sensitivity, and efficiency, thereby improving CE performance for complex biological analysis.

Development of the Diffusive Gradient in Thin Film (DGT) Method with CaO/Biochar Binding Agent from Eggshells and Rice Straw Waste for Determining the Concentration of Phosphate

Phosphorus, often found in the form of phosphate in the environment, especially aquatic environments, has been identified as the primary contaminant that causes algae blooms and eutrophication. Phosphate adsorption in the aquatic environment was carried out by comparing the adsorption capabilities of eggshell (CaO), rice straw (BC) and CaO/biochar materials at mass variations of 1:1, 1:2 and 2:1 from the use of eggshell and rice straw waste. Each material was synthesized using ball milling and pyrolysis methods. The adsorption isotherm and kinetics of the material are by the Langmuir adsorption isotherm and are pseudo-second-order (PSO) adsorption kinetics. The CaO/biochar 1:2 material shows the highest phosphate adsorption capacity at pH 12 with a contact time of 24 hours. CaO/biochar 1:2 was applied in the phosphate adsorption process using the Diffusive Gradient in Thin Film method as a binding agent, which acts as an adsorbent. The DGT technique is an in situ sample preparation technique for identifying the presence of phosphate, a labile species. The binding agent material was characterized using FTIR, XRD, and BJH-BET instruments. The success of synthesizing CaO/biochar 1:2 binding gel and ferrihydrite was demonstrated by the appearance of the same adsorption as the diffusive gel using FTIR. The CaO/biochar binding gel demonstrated that it is a better material compared to the ferrihydrite binding gel for phosphate adsorption, achieving CDGT values of 10.1727 mg/L and 2.5959 mg/L at pH 5 and 3, respectively, with a phosphate concentration of 10 mg/L. These findings underscore the potential of CaO/biochar as a more effective material for phosphate removal applications.

Sensing volatile organic compounds in aquatic samples: a review

ABSTRACT Volatile organic compounds (VOCs) are toxic and harmful to human health; thus, their detection in water samples is critical for ensuring safe drinking water and protecting public health. The aim of this review was to explore the various techniques available in the literature for detecting VOCs in water samples and discuss their features, advantages, and limitations in facilitating fast and rapid VOC analysis. Established techniques such as gas chromatography and mass spectrometry offer high sensitivity and selectivity but are often hindered by complexity and cost. In contrast, emerging technologies like microfluidic gas sensors and cantilever-based sensors provide portable and real-time monitoring capabilities, although they may be susceptible to matrix effects. Overcoming these challenges requires advanced sample preparation techniques and method optimization. Additionally, the integration of machine learning algorithms and nanotechnology shows promise for enhancing sensitivity and precision in the detection of VOCs. By overcoming these limitations and leveraging technological advancements, researchers can improve water quality monitoring and help protect the environment.

A method for quantitative spatial analysis of immunolabeled fibers at regenerative electrode interfaces

BackgroundRegenerative electrodes are being explored as robust peripheral nerve interfaces for neuro-prosthetic control and sensory feedback. Current designs differ in electrode number, spatial arrangement, and porosity which impacts the regeneration, activation, and spatial distribution of fibers at the device interface. Knowledge of sensory and motor fiber distributions are important in optimizing selective fiber activation and recording. New MethodWe use confocal microscopy and immunofluorescence methods to conduct spatial analysis of immunolabeled fibers across whole nerve cross sections. ResultsThis protocol was implemented to characterize motor fiber distribution within 3 macro-sieve electrode regenerated (MSE), 3 silicone-conduit regenerated, and 3 unmanipulated control rodent sciatic nerves. Total motor fiber counts were 1485 [SD: +/- 50.11], 1899 [SD: +/- 359], and 5732 [SD: +/- 1410] for control, MSE, and conduit nerves respectively. MSE motor fiber distributions exhibited evidence of deviation from complete spatial randomness and evidence of dispersion and clustering tendencies at varying scales. Notably, MSE motor fibers exhibited clustering within the central portion of the cross section, whereas conduit regenerated motor fibers exhibited clustering along the periphery. Comparison with Existing MethodsPrior exploration of fiber distributions at regenerative interfaces was limited to either quadrant-based density analysis of randomly sampled subregions or qualitative description. This method extends existing sample preparation and microscopy techniques to quantitatively assess immunolabeled fiber distributions within whole nerve cross-sections. ConclusionsThis approach is an effective way to examine the spatial organization of fiber subsets at regenerative electrode interfaces, enabling robust assessment of fiber distributions relative to electrode arrangement.

Spectroscopic techniques and chemometrics for ink analysis: Document analysis application

This study represents a methodology to determine the falsified documents via a combined method of spectroscopic techniques and chemometrics. The techniques of UV–Vis and FTIR-ATR spectroscopies and principal component analysis methods have been applied to black, blue, and red ballpoint pens available in the Türkiye market. The analysis results of the applied spectroscopic techniques were found to be consistent with each other for the examined eleven ink samples from three different brands, and it was observed that FTIR-ATR spectroscopy had higher discriminative power. A dried sample preparation technique developed for small amounts of samples for FTIR-ATR measurements and the increased the sensitivity of FTIR-ATR technique was associated with this sample preparation method. Statistical techniques showed that the UV–Vis technique proves useful outcomes in distinguishing inks according to their colors, whereas the FTIR-ATR technique is valuable for identifying ink brands. Additional analysis of the sub-brand of black inks and falsified old-dated check sample analysis validated that our methodology has the potential to classify and identify ballpoint inks in forensic applications. Due to the limited sample quantity available for analysis in real samples, only FTIR-ATR analysis was possible, and the results demonstrated that document forgery could be detected from small parts of samples in the document. When we look at the overall outcome of this study, a comprehensive methodology enriched with statistical calculations has been proposed that can be applied even in a laboratory with limited resources, having only UV–Vis and FTIR-ATR capabilities.

Interaction between modified magnetic nanoparticles and human albumin: Kinetics and isotherm studies and application in protein depletion

Magnetic nanoparticles modified with tetraethyl orthosilicate (Fe3O4@TEOS) and bovine serum albumin (Fe3O4@TEOS@BSA) were evaluated as sorbent in albumin depletion from human serum samples by magnetic dispersive solid phase extraction. Characterization studies were carried out by X-ray diffraction, thermogravimetry, Fourier transform infrared spectroscopy, zeta potential, and scanning electron microscopy. Both nanoparticles also showed high thermal stability and pH-dependent surface charges. The human serum albumin adsorption protocol was optimized using a central composite rotatable design. Nanoparticle mass, pH, and albumin concentration were the most influential variables. Avrami's fractional order and Freundlich isotherm models best fitted the data for human albumin adsorption kinetic and isotherm studies for Fe3O4@TEOS and Fe3O4@TEOS@BSA, and the maximum adsorption capacities were 11.93 and 14.89 mg g−1, respectively. The protein desorption was influenced by the pH of samples and eluent volume. Electrophoresis in a polyacrylamide gel containing sodium dodecyl sulfate showed different patterns of serum protein bands when consecutive depletions were performed. The Fe3O4@TEOS showed greater affinity for HSA and efficiency in depletion. The process was versatile, and the depleted albumin proportion could be controlled by the nanoparticle masses. The proposed method is a powerful sample preparation technique for rapid, reliable, and specific depletion of albumin.