Analytical and Bioanalytical Chemistry最新文献

A molecular beacon is an oligonucleotide hybridization probe that can report the presence of specific nucleic acids in homogeneous solutions. Using an aptamer has allowed an aptamer-based molecular beacon-aptamer beacon to be developed, which has shown advantages of simplicity, rapidity, and sensitivity in imaging and sensing non-nucleic acid substances. However, due to requirement for a deliberate DNA hairpin structure for the preparation of a molecular beacon, not any given aptamer is suitable for designing an aptamer beacon probe. This paper provides a general design strategy for the preparation of an aptamer beacon probe, which theoretically can be used for any given aptamer. Through coupling an aptamer and a short complementary DNA into one DNA molecule via a rational poly thymidine (T) linker, novel molecular beacon probes are successfully prepared and used for the detection of targets (aflatoxin B1 and ochratoxin A). The working mechanism of this aptamer beacon probe is based on intramolecular hybridization/dehybridization, which is more efficient than commonly aptasensor strategies based on intermolecular reactions. This aptamer beacon probe shows advantages of low background, a signal-on response, a large signal change, as well as simplicity and rapidity of analysis, which have promising application potential.

The visual evaluation of data derived from screening and optimization experiments in the development of new analytical methods poses a considerable time investment and introduces the risk of subjectivity. This study presents a novel approach to processing such data, based on factor analysis of mixed data and hierarchical clustering - multivariate techniques implemented in the R programming language. The methodology is demonstrated in the early-stage screening and optimization of the chromatographic separation of 15 structurally diverse drugs that affect the central nervous system, using a custom R Language script. The presented explorative approach enabled the identification of key parameters affecting the separation and significantly reduced the time required to evaluate the comprehensive dataset from the screening experiments. Based on the data analysis results, the optimal combination of stationary phase and mobile phase composition was selected, considering retention, overall resolution, and peak shape of compounds. Additionally, compounds vulnerable to changes in selected chromatographic conditions were identified. As a complement to the presented R Language script, a web-based application ChromaFAMDeX has been developed to offer an intuitive interface that enhances the accessibility of the used statistical methods. Accompanying the publication, the R script and the link to the standalone application are provided, enabling replication and adaptation of the methodology.

The recent surge in popularity of cannabidiol-infused products extends beyond food and supplements to the cosmetic industry. Accurate labeling remains a significant concern, as many products fail to meet advertised cannabidiol content and/or contain psychoactive tetrahydrocannabinol above the permissible levels. In this work, we present the use of an HPLC-UV-MS/MS method for the quantification of five major cannabinoids (cannabidiol, cannabidiolic acid, tetrahydrocannabinol, tetrahydrocannabinolic acid, and cannabigerol) in oil-in-water cosmetic emulsions. The sample extraction is based on dispersing the sample in isopropanol, followed by solid-phase extraction using Bond Elut Plexa PAX cartridge. The viability of this method is demonstrated by comparing matrix effects in samples subjected to solid-phase extraction (0‒11% suppression of cannabidiol ionization) to samples extracted without additional purification steps (0‒84% ionization suppression of cannabidiol ionization). The limit of quantification is determined at 0.1 mg/g and the calibration is employed in the range of 0.1‒50 mg/g for cannabidiol and 0.1‒10 mg/g for all other analytes. Finally, 36 real cosmetic samples from the Czech market were analyzed. Of these, 14 indicated the amount of CBD on the label but only five (36%) were accurate, i.e., within 90‒110% of the labeled amount, and a considerable amount of THC (0.16 ± 0.01 mg/g) was found in one sample. These findings contribute to the cumulating evidence that cannabidiol-based consumer products are often mislabeled and highlight the importance of better regulatory compliance.

A polarimeter is a common but critical instrument for measuring the optical rotation of chiral compounds, ranging from the pharmaceutical to chemical industry, or even employed in monitoring chemical reactions for research purposes. Developing a portable polarimeter helps to transfer the measurements from the laboratory to on-site detection. Herein, we design a new portable polarimeter with a "hand-held" scale. Technically, we innovatively adopted a rotary potentiometer coupled with a high-precision voltmeter to signify the angle changes after polarized light travels through the chiral compound solution. Compared with the commercial disc polarimeter that uses a dial to measure the optical rotation, such a design shows superiority in being easy to read. This "hand-held" polarimeter meets the high demand for on-site detection on the premise of low cost. Bland-Altman analysis results showed consistency between our device's optical rotation detection method and the commercial disc polarimeter. The "hand-held" polarimeter can measure the optical rotation of a chiral drug and be applicable to monitor the progress of a chemical reaction. As such, this "hand-held" polarimeter shows great potential to assist scientists in scientific research, or for on-site measurement with high portability.

Non-targeted analysis (NTA) is commonly used for the detection and identification of emerging pollutants, including many per- and polyfluoroalkyl substances (PFAS). While NTA outputs are often non-quantitative, concentration estimation is now possible using quantitative non-targeted analysis (qNTA) approaches. To date, few studies have examined matrix effects on qNTA performance, and little is therefore known about the implications of matrix effects on qNTA results and interpretations. Using a set of 19 PFAS, we examined the impacts of drinking water (DW) and waste-activated sludge matrices on qNTA performance across three qNTA approaches: one structure-independent approach based on "global" surrogates and two structure-dependent approaches based on "expert-selected" surrogates and predicted ionization efficiency (IE) regression. The performance of each qNTA approach was examined separately for the PFAS prepared in pure solvent, DW extract, and sludge extract using leave-one-out modeling. Performance was evaluated using previously defined qNTA metrics that describe predictive accuracy, uncertainty, and reliability. The studied sample matrices had minimal effects on qNTA accuracy and larger effects on qNTA uncertainty and reliability. Using solvent-based surrogate data to inform matrix-based estimations yielded lower uncertainty, but also lower reliability, emphasizing that uncertainty must be considered in context of reliability. No single qNTA approach uniformly performed best across all comparisons. Since the IE regression and global surrogates approaches proved most reliable, we recommended them for future qNTA applications. This study highlights the importance of examining multiple performance metrics and utilizing matrix-matched surrogate data in qNTA studies.

Metal-organic frameworks (MOFs) are often applied for enzyme immobilization, while they are limited for bioelectrochemical applications due to poor electronic conductivity. Two-dimensional (2D) metal-organic layers (MOLs) with an ultra-thin lamellar structure can effectively shorten the electron transport path and improve the electron transfer rate. In this study, ferrocene as an electron mediator is covalently bound to a 2D-MOL (Fc-NH₂-Hf-BTB-MOL) to accelerate electron transfer between the electrode surface and enzyme. Glucose oxidase (GOx) is immobilized on the electrode modified with Fc-NH₂-Hf-BTB-MOL with the addition of chitosan and carboxylated carbon nanotubes. Electrochemical tests such as cyclic voltammetry are carried out on the glucose biosensor, which shows linear detection ranges of 5 ~ 400 μM and 3 ~ 9 mM, with a detection limit of 3.9 μM (S/N = 3). Therefore, this strategy of construction of an enzyme electrode based on 2D-MOLs with enhanced electron transfer results in a biosensor with excellent specificity and activity for practical glucose detection.

In this study, we developed a customized high-resolution mass spectrometry metabolomics workflow integrating the dual sugar test employing lactulose and mannitol as test probes for intestinal permeability assessment with untargeted screening of small molecules. Urine samples were collected from patients with major depression and healthy controls as part of a clinical study at the psychiatric department. Using a dual injection/dual chromatography setup, the test probes were quantified by hydrophilic interaction liquid chromatography (HILIC) in a targeted assay, while drugs and their metabolites were profiled in an untargeted manner by reversed-phase separation. Rigorous method development and validation allowed for selective separation of sugar isomers and consequently accurate quantification of lactulose and mannitol in urine. Internal standardization with compound specific stable isotope-labeled standards enabled excellent analytical figures of merit such as high recoveries, precision (< 5%), and working range (5 orders of magnitude). Within one analytical run, intestinal permeability was assessed together with drugs and their metabolites, allowing to screen for confounding drugs and patient compliance to the therapeutic scheme.

A vital challenge in using imprinted membranes for selective sensing is their non-specific adsorption (NSA). In this study, a novel, rapid, and green approach of NSA-free molecularly imprinted membrane (MIM) preparation was proposed. Sodium alginate was employed as a functional polymer (to interact with the template) and as a membrane matrix, then cross-linked with calcium before template removal to block the unreacted groups, followed by exposure to phosphate to chelate any remaining sites. Unlike the non-imprinted membrane (NIM), which is prepared similarly to MIM and lacks the template cavities, the MIM demonstrated exceptional imprinting factor (IF) (Q(NIM) ≈ 0 mg/g) compared to the initial IF of around 4 before NSA suppress, and a selectivity factor over 10 times greater than that of existing MIMs in the literature. The NSA-free MIM was used as a ready-to-use sensor for spectro-fluorescence and smartphone-based fluorescence detection of tetracycline (TC), achieving detection limits of 0.005 mg/L and 0.015 mg/L, respectively, which were below the maximal acceptable concentrations of TC in real samples. The detection of TC in milk and honey samples using the NSA-free MIM showed significant recoveries (86-101%) compared to those found by MIM before NSA supress (114-122%). The proposed methodology serves as an inspiration for extending NSA removal strategies to other MIMs based on various anionic polymers, including carboxylate, sulfonate, phosphonate, and phenolate anionic groups.

Recently, the use of mass distribution-based isotopic shifts in high-resolution ion mobility spectrometry-mass spectrometry-based separations have enabled isomer delineation by measuring the relative arrival times of their heavy and light isotopologues. However, all previous efforts to induce such shifts have focused solely on the introduction of one type of isotopic substitution for a given molecule or isomer set. Herein, for the first time, we present a two-dimensional isotopic labeling strategy where two unique derivatizations are performed on various steroid isomer molecules to induce two distinct isotopic shifts and thus simultaneously measure them in a single ion mobility separations experiment. Derivatization strategies were chosen to target two specific functional groups in these steroids (i.e., hydroxyl and carbonyl), and heavy-labeled versions of the derivatizing reagents were used to induce isotopic shifts at each of these positions. We found that isotopic shifts were orthogonal to one another, diagnostic for certain steroid isomers, and that the simultaneous analysis of two different isotopic shifts was necessary for complete characterization of each steroid isomer set. We envision this multidimensional isotopic shift strategy as a new method for delineating amongst isomeric molecules, especially those with several different functional groups causing their isomerism.