Showing papers in "Analytical and Bioanalytical Chemistry in 2016"
TL;DR: A further size division within the smaller microplastics fraction into 500–50 μm (rapid and reliable analysis by FTIR imaging) and into 50–1 μm (detailed and more time-consuming analysis by Raman imaging) is proposed.
Abstract: The contamination of aquatic ecosystems with microplastics has recently been reported through many studies, and negative impacts on the aquatic biota have been described. For the chemical identification of microplastics, mainly Fourier transform infrared (FTIR) and Raman spectroscopy are used. But up to now, a critical comparison and validation of both spectroscopic methods with respect to microplastics analysis is missing. To close this knowledge gap, we investigated environmental samples by both Raman and FTIR spectroscopy. Firstly, particles and fibres >500 μm extracted from beach sediment samples were analysed by Raman and FTIR microspectroscopic single measurements. Our results illustrate that both methods are in principle suitable to identify microplastics from the environment. However, in some cases, especially for coloured particles, a combination of both spectroscopic methods is necessary for a complete and reliable characterisation of the chemical composition. Secondly, a marine sample containing particles <400 μm was investigated by Raman imaging and FTIR transmission imaging. The results were compared regarding number, size and type of detectable microplastics as well as spectra quality, measurement time and handling. We show that FTIR imaging leads to significant underestimation (about 35 %) of microplastics compared to Raman imaging, especially in the size range <20 μm. However, the measurement time of Raman imaging is considerably higher compared to FTIR imaging. In summary, we propose a further size division within the smaller microplastics fraction into 500–50 μm (rapid and reliable analysis by FTIR imaging) and into 50–1 μm (detailed and more time-consuming analysis by Raman imaging).
522 citations
TL;DR: An overview of spICP-MS development from a niche technique to application for routine analysis, a discussion of the key issues for quantitative analysis, and examples of its further advancement for analysis of increasingly complex environmental and biological samples are provided.
Abstract: From its early beginnings in characterizing aerosol particles to its recent applications for investigating natural waters and waste streams, single particle inductively coupled plasma-mass spectrometry (spICP-MS) has proven to be a powerful technique for the detection and characterization of aqueous dispersions of metal-containing nanomaterials. Combining the high-throughput of an ensemble technique with the specificity of a single particle counting technique and the elemental specificity of ICP-MS, spICP-MS is capable of rapidly providing researchers with information pertaining to size, size distribution, particle number concentration, and major elemental composition with minimal sample perturbation. Recently, advances in data acquisition, signal processing, and the implementation of alternative mass analyzers (e.g., time-of-flight) has resulted in a wider breadth of particle analyses and made significant progress toward overcoming many of the challenges in the quantitative analysis of nanoparticles. This review provides an overview of spICP-MS development from a niche technique to application for routine analysis, a discussion of the key issues for quantitative analysis, and examples of its further advancement for analysis of increasingly complex environmental and biological samples. Graphical Abstract Single particle ICP-MS workflow for the analysis of suspended nanoparticles.
242 citations
TL;DR: The results provide the biochemical basis for the development of SERS as a rapid bacterial diagnostic and illustrate how SERS can be applied more generally for metabolic profiling as a probe of cellular activity.
Abstract: The dominant molecular species contributing to the surface-enhanced Raman spectroscopy (SERS) spectra of bacteria excited at 785 nm are the metabolites of purine degradation: adenine, hypoxanthine, xanthine, guanine, uric acid, and adenosine monophosphate. These molecules result from the starvation response of the bacterial cells in pure water washes following enrichment from nutrient-rich environments. Vibrational shifts due to isotopic labeling, bacterial SERS spectral fitting, SERS and mass spectrometry analysis of bacterial supernatant, SERS spectra of defined bacterial mutants, and the enzymatic substrate dependence of SERS spectra are used to identify these molecular components. The absence or presence of different degradation/salvage enzymes in the known purine metabolism pathways of these organisms plays a central role in determining the bacterial specificity of these purine-base SERS signatures. These results provide the biochemical basis for the development of SERS as a rapid bacterial diagnostic and illustrate how SERS can be applied more generally for metabolic profiling as a probe of cellular activity.
192 citations
TL;DR: This review aims to provide insight into advances of plant and animal DNA barcoding and highlights current practices and recent developments for DNA metabarcoding of food and wildlife forensic samples from a practical point of view.
Abstract: Species identification using DNA barcodes has been widely adopted by forensic scientists as an effective molecular tool for tracking adulterations in food and for analysing samples from alleged wildlife crime incidents. DNA barcoding is an approach that involves sequencing of short DNA sequences from standardized regions and comparison to a reference database as a molecular diagnostic tool in species identification. In recent years, remarkable progress has been made towards developing DNA metabarcoding strategies, which involves next-generation sequencing of DNA barcodes for the simultaneous detection of multiple species in complex samples. Metabarcoding strategies can be used in processed materials containing highly degraded DNA e.g. for the identification of endangered and hazardous species in traditional medicine. This review aims to provide insight into advances of plant and animal DNA barcoding and highlights current practices and recent developments for DNA metabarcoding of food and wildlife forensic samples from a practical point of view. Special emphasis is placed on new developments for identifying species listed in the Convention on International Trade of Endangered Species (CITES) appendices for which reliable methods for species identification may signal and/or prevent illegal trade. Current technological developments and challenges of DNA metabarcoding for forensic scientists will be assessed in the light of stakeholders’ needs.
160 citations
TL;DR: A spectral collection of over 150 ATR-FT-IR spectra of materials related to cultural heritage and conservation science has been presented that have been measured in the extended region of 4000-80 cm–1 (mid-IR and far-IR region).
Abstract: In this paper, a spectral collection of over 150 ATR-FT-IR spectra of materials related to cultural heritage and conservation science has been presented that have been measured in the extended region of 4000-80 cm–1 (mid-IR and far-IR region). The applicability of the spectra and, in particular, the extended spectral range, for investigation of art-related materials is demonstrated on a case study. This collection of ATRFT-IR reference spectra is freely available online (
http://tera.chem.ut.ee/IR_spectra/
) and is meant to be a useful tool for researchers in the field of conservation and materials science.
157 citations
TL;DR: This paper will summarize and critically review the exhaled-breath VOC-related sampling, collection, detection, and analytical methods, especially the recent development in VOC sensors.
Abstract: The detection of cancer at an early stage is often significant in the successful treatment of the disease. Tumor cells have been reported to generate unique cancer volatile organic compound (VOC) profiles which can reflect the disease conditions. The detection and analysis of VOC biomarkers from exhaled breath has been recognized as a new frontier in cancer diagnostics and health inspections owing to its potential in developing rapid, noninvasive, and inexpensive cancer screening tools. To detect specific VOCs of low concentrations from exhaled breath, and to enhance the accuracy of early diagnosis, many breath collection and analysis approaches have been developed. This paper will summarize and critically review the exhaled-breath VOC-related sampling, collection, detection, and analytical methods, especially the recent development in VOC sensors. VOC sensors are commonly inexpensive, portable, programmable, easy to use, and can obtain data in real time with high sensitivities. Therefore, many sensor-based VOC detection techniques have huge potential in clinical point-of-care use.
124 citations
TL;DR: The state-of-the-art of peptidomics methods for the identification and discovery of bioactive peptides are described, also considering recent progress in their analysis and highlighting the difficulty in the analysis of short amino acid sequences and endogenous peptides.
Abstract: Food-derived constituents represent important sources of several classes of bioactive compounds. Among them peptides have gained great attention in the last two decades thanks to the scientific evidence of their beneficial effects on health in addition to their established nutritional value. Several functionalities for bioactive peptides have been described, including antioxidative, antihypertensive, anti-inflammatory, immunomodulatory, and antimicrobial activity. They are now considered as novel and potential dietary ingredients to promote human health, though in some cases they may also have detrimental effects on health. Bioactive peptides can be naturally occurring, produced in vitro by enzymatic hydrolysis, and formed in vivo during gastrointestinal digestion of proteins. Thus, the need to gain a better understanding of the positive health effects of food peptides has prompted the development of analytical strategies for their isolation, separation, and identification in complex food matrices. Dairy products and milk are potential sources of bioactive peptides: several of them possess extra-nutritional physiological functions that qualify them to be classified under the functional food label. In this trends article we briefly describe the state-of-the-art of peptidomics methods for the identification and discovery of bioactive peptides, also considering recent progress in their analysis and highlighting the difficulty in the analysis of short amino acid sequences and endogenous peptides.
115 citations
TL;DR: This review focuses on several post-SELEX optimization strategies of aptamers identified in recent years and describes four common methods in detail: truncation, chemical modification, bivalent or multivalent aptamer construction, and mutagenesis.
Abstract: Aptamers are functional single-stranded DNA or RNA oligonucleotides, selected in vitro by SELEX (Systematic Evolution of Ligands by Exponential Enrichment), which can fold into stable unique three-dimensional structures that bind their target ligands with high affinity and specificity. Although aptamers show a number of favorable advantages such as better stability and easier modification when compared with the properties of antibodies, only a handful of aptamers have entered clinical trials and only one, pegaptanib, has received US Food and Drug Administration approval for clinical use. The main reasons that limit the practical application of aptamers are insufficient nuclease stability, bioavailability, thermal stability, or even affinity. Some aptamers obtained from modified libraries show better properties; however, polymerase amplification of nucleic acids containing non-natural bases is currently a primary drawback of the SELEX process. This review focuses on several post-SELEX optimization strategies of aptamers identified in recent years. We describe four common methods in detail: truncation, chemical modification, bivalent or multivalent aptamer construction, and mutagenesis. We believe that these optimization strategies should improve one or more specific properties of aptamers, and the type of feature(s) selected for improvement will be dependent on the application purpose.
111 citations
TL;DR: A minimally invasive glucose biosensor based on a microneedle array electrode fabricated from an epoxy-based negative photoresist and designed for continuous measurement in the dermal compartment with minimal pain is described.
Abstract: We describe here a minimally invasive glucose biosensor based on a microneedle array electrode fabricated from an epoxy-based negative photoresist (SU8 50) and designed for continuous measurement in the dermal compartment with minimal pain. These minimally invasive, continuous monitoring sensor devices (MICoMS) were produced by casting the structures in SU8 50, crosslinking and then metallising them with platinum or silver to obtain the working and reference electrodes, respectively. The metallised microneedle array electrodes were subsequently functionalised by entrapping glucose oxidase in electropolymerised polyphenol (PP) film. Sensor performance in vitro showed that glucose concentrations down to 0.5 mM could be measured with a response times (T90) of 15 s. The effect of sterilisation by Co60 irradiation was evaluated. In preparation for further clinical studies, these sensors were tested in vivo in a healthy volunteer for a period of 3–6 h. The sensor currents were compared against point measurements obtained with a commercial capillary blood glucometer. The epoxy MICoMS devices showed currents values that could be correlated with these.
97 citations
TL;DR: This review article summarizes the efforts made to produce VHHs to various environmental targets, compares the VHH-based assays with conventional antibody assays, and discusses the advantages and limitations in developing these new antibody reagents particularly to small molecule targets.
Abstract: A VHH antibody (or nanobody) is the antigen binding fragment of heavy chain only antibodies Discovered nearly 25 years ago, they have been investigated for their use in clinical therapeutics and immunodiagnostics, and more recently for environmental monitoring applications A new and valuable immunoreagent for the analysis of small molecular weight environmental chemicals, VHH will overcome many pitfalls encountered with conventional reagents In the work so far, VHH antibodies often perform comparably to conventional antibodies for small molecule analysis, are amenable to numerous genetic engineering techniques, and show ease of adaption to other immunodiagnostic platforms for use in environmental monitoring Recent reviews cover the structure and production of VHH antibodies as well as their use in clinical settings However, no report focuses on the use of these VHH antibodies to detect small environmental chemicals (MW < 1500 Da) This review article summarizes the efforts made to produce VHHs to various environmental targets, compares the VHH-based assays with conventional antibody assays, and discusses the advantages and limitations in developing these new antibody reagents particularly to small molecule targets
97 citations
TL;DR: The potential and challenges of mid-infrared spectroscopy for protein analysis are discussed as are the potential and limitations of different IR spectroscopic techniques enabling protein analysis.
Abstract: Mid-infrared (MIR) spectroscopy investigates the interaction of MIR photons with both organic and inorganic molecules via the excitation of vibrational and rotational modes, providing inherent molecular selectivity. In general, infrared (IR) spectroscopy is particularly sensitive to protein structure and structural changes via vibrational resonances originating from the polypeptide backbone or side chains; hence information on the secondary structure of proteins can be obtained in a label-free fashion. In this review, the challenges for IR spectroscopy for protein analysis are discussed as are the potential and limitations of different IR spectroscopic techniques enabling protein analysis. In particular, the amide I spectral range has been widely used to study protein secondary structure, conformational changes, protein aggregation, protein adsorption, and the formation of amyloid fibrils. In addition to representative examples of the potential of IR spectroscopy in various fields related to protein analysis, the potential of protein analysis taking advantage of miniaturized MIR systems, including waveguide-enhanced MIR sensors, is detailed.
TL;DR: A theoretical overview of the techniques and underlying physics are presented, followed by a practical guide to all of the facets involved in designing a super-resolution experiment, including an approachable explanation of the photochemistry involved, labeling methods available, and sample preparation procedures.
Abstract: Super-resolution microscopy is the term commonly given to fluorescence microscopy techniques with resolutions that are not limited by the diffraction of light. Since their conception a little over a decade ago, these techniques have quickly become the method of choice for many biologists studying structures and processes of single cells at the nanoscale. In this review, we present the three main approaches used to tackle the diffraction barrier of ∼200 nm: stimulated-emission depletion (STED) microscopy, structured illumination microscopy (SIM), and single-molecule localization microscopy (SMLM). We first present a theoretical overview of the techniques and underlying physics, followed by a practical guide to all of the facets involved in designing a super-resolution experiment, including an approachable explanation of the photochemistry involved, labeling methods available, and sample preparation procedures. Finally, we highlight some of the most exciting recent applications of and developments in these techniques, and discuss the outlook for this field.
TL;DR: The present study reports a highly simple and rapid method for the detection of a widely used and extremely toxic organophosphorus pesticide, phorate, which employs a pesticide-specific aptamer as the recognition element and gold nanoparticles as the optical sensors.
Abstract: The present study reports a highly simple and rapid method for the detection of a widely used and extremely toxic organophosphorus pesticide, phorate. The detection employs a pesticide-specific aptamer as the recognition element and gold nanoparticles as the optical sensors. The aptamer, owing to its random coil structure, provides stability to the gold nanoparticles upon linking, thereby keeping the nanoparticles well dispersed. However, on the addition of the target pesticide, the aptamer acquires a rigid conformation resulting in the aggregation of the gold nanoparticles. Consequently, the color of the solution changes from red to blue and is easily observable with the naked eye. The proposed method was linear in the concentration range of 0.01 nM to 1.3 μm with the limit of detection as low as 0.01 nM. Moreover, the proposed assay selectively recognized phorate in the presence of other interfering substances and, thus, can be applied to real samples for the rapid and efficient screening of phorate.
TL;DR: A non-targeted lipidomics strategy using ultra performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry was performed to reveal differential lipids between MDD and healthy controls and provides a specific potential biomarker for MDD diagnose.
Abstract: Major depressive disorder (MDD) is a grave debilitating mental disease with a high incidence and severely impairs quality of life. Therefore, its physiopathological basis study and diagnostic biomarker discovery are extremely valuable. In this study, a non-targeted lipidomics strategy using ultra performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF/MS) was performed to reveal differential lipids between MDD (n = 60) and healthy controls (HCs, n = 60). Validation of changed lipid species was performed in an independent batch including 75 MDD and 52 HC using the same lipidomic method. Pronouncedly changed lipid species in MDD were discovered, which mainly were lysophosphatidylcholine (LPC), lysophosphatidylethanolamine (LPE), phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylinositol (PI), 1-O-alkyl-2-acyl-PE (PE O), 1-O-alkyl-2-acyl-PC (PC O), sphingomyelin (SM), diacylglycerol (DG), and triacylglycerol (TG). Among these lipid species, LPC, LPE, PC, PE, PI, TG, etc. remarkably increased in MDD and showed pronounced positive relationships with depression severity, while 1-O-alkyl-2-acyl-PE and SM with odd summed carbon number significantly decreased in MDD and demonstrated negative relationships with depression severity. A combinational lipid panel including LPE 20:4, PC 34:1, PI 40:4, SM 39:1, 2, and TG 44:2 was defined as potential diagnostic biomarker with a good sensitivity and specificity for distinguishing MDD from HCs. Our study brings insights into lipid metabolism disorder in MDD and provides a specific potential biomarker for MDD diagnose.
TL;DR: The usefulness of the nanochip platform-based techniques for medical diagnostics was illustrated by the detection of host genetic biomarkers for respiratory viral infection and of the dengue virus gene.
Abstract: The development of rapid, cost-effective DNA detection methods for molecular diagnostics at the point-of-care (POC) has been receiving increasing interest. This article reviews several DNA detection techniques based on plasmonic-active nanochip platforms developed in our laboratory over the last 5 years, including the molecular sentinel-on-chip (MSC), the multiplex MSC, and the inverse molecular sentinel-on-chip (iMS-on-Chip). DNA probes were used as the recognition elements, and surface-enhanced Raman scattering (SERS) was used as the signal detection method. Sensing mechanisms were based on hybridization of target sequences and DNA probes, resulting in a distance change between SERS reporters and the nanochip’s plasmonic-active surface. As the field intensity of the surface plasmon decays exponentially as a function of distance, the distance change in turn affects SERS signal intensity, thus indicating the presence and capture of the target sequences. Our techniques were single-step DNA detection techniques. Target sequences were detected by simple delivery of sample solutions onto DNA probe-functionalized nanochips and measuring the SERS signal after appropriate incubation times. Target sequence labeling or washing to remove unreacted components was not required, making the techniques simple, easy-to-use, and cost-effective. The usefulness of the nanochip platform-based techniques for medical diagnostics was illustrated by the detection of host genetic biomarkers for respiratory viral infection and of the dengue virus gene.
TL;DR: A growing trend in recent years has been the use of molecularly imprinted polymers as replacements for antibodies in various assay formats, as indicated by a steady increase in publications in the area.
Abstract: Many efforts have been made to produce artificial materials with biomimetic properties for applications in binding assays. Among these efforts, the technique of molecular imprinting has received much attention because of the high selectivity obtainable for molecules of interest, robustness of the produced polymers, simple and short synthesis, and excellent cost efficiency. In this review, progress in the field of molecularly imprinted sorbent assays is discussed—with a focus on work conducted from 2005 to date.
TL;DR: AuNPs applications for analytical, biotechnology and proteomics, Characterization of Au nanoclusters (AuNCs) by mass spectrometry, pros and cons were also highlighted.
Abstract: Gold nanoparticles (AuNPs) assisted laser desorption/ionization mass spectrometry (GALDI-MS) provided new horizons and offered many functions for various applications. This review summarized AuNPs applications for analytical, biotechnology and proteomics. AuNPs efficiently absorbed the laser radiation and transferred the energy to the analyte for the desorption/ionization process. The unique features of AuNPs such as large surface area and high absorption coefficient lead not only to high resolution, low interference and low limit of detection, but also offered selective detection for certain species. AuNPs provided an excellent surface for the analysis of several species such as small molecules, biomarkers, proteins and cells (pathogenic bacteria or cancer cells). AuNPs played many roles such as surface for LDI-MS, probe and stationary phase for separation or preconcentration. AuNPs modified various surface chemistry was applied for a wide range of different wavelength. AuNPs severed as a source of Au(+) ions that were suitable for analyte cationisation. Characterization of Au nanoclusters (AuNCs) by mass spectrometry, pros and cons were also highlighted. Graphical Abstract Schematic representation of the analysis by Gold Nanoparticles Assisted Laser Desorption/Ionization Mass Spectrometry (GALDI-MS).
TL;DR: Results indicate a significant benefit in extraction efficiency due to the larger sorption phase volume of the novel PAL SPME Arrow, accompanied by faultless mechanical robustness and thus better reliability, especially in case of prolonged, unattended, and automated operation.
Abstract: After more than 25 years, solid-phase microextraction (SPME) has gained widespread acceptance as a well-automatable and flexible microextraction technique, while its instrumental basis remained mostly unchanged. The novel PAL (Prep And Load solution) SPME Arrow combines the advantages of SPME with the benefits of extraction techniques providing larger sorption phase volumes such as stir bar sorptive extraction (SBSE). It thereby avoids the inherent drawbacks of both techniques such as limitations in method automation in the case of SBSE, as well as the small sorption phase volumes and the lacking fiber robustness of classical SPME fibers. This new design is based on a robust stainless steel backbone, carrying, the screw connection to the PAL sampler, the enlarged sorption phase, and an arrow-shaped tip for conservative penetration of septa (hence the name). An outer capillary encloses this phase apart from enrichment and desorption processes and rests against the tip during transfer and penetrations, resulting in a homogeneously closed device. Here, we present an evaluation and a comparison of the novel PAL SPME Arrow with classical SPME fibers, extracting polycyclic aromatic hydrocarbons (PAHs) as model analytes, from the freely dissolved fraction in lab water and groundwater via direct immersion using polydimethylsiloxane (PDMS) as common sorption phase material. Limits of detection, repeatabilities, and extraction yields were determined for the PAL SPME Arrow and compared to data of classical SPME fibers and SBSE bars. Results indicate a significant benefit in extraction efficiency due to the larger sorption phase volume. It is accompanied by faultless mechanical robustness and thus better reliability, especially in case of prolonged, unattended, and automated operation. As an exemplary application, the water-soluble fraction of PAHs and derivatives in a roofing felt sample was quantified.
TL;DR: This review presents a combined survey of various approaches to formulate glucose sensors using various nanostructure materials, with emphasis on the current progress in the use of electrospun nanofibers and their composites.
Abstract: The worldwide increase in the number of people suffering from diabetes has been the driving force for the development of glucose sensors. The recent past has devised various approaches to formulate glucose sensors using various nanostructure materials. This review presents a combined survey of these various approaches, with emphasis on the current progress in the use of electrospun nanofibers and their composites. Outstanding characteristics of electrospun nanofibers, including high surface area, porosity, flexibility, cost effectiveness, and portable nature, make them a good choice for sensor applications. Particularly, their nature of possessing a high surface area makes them the right fit for large immobilization sites, resulting in increased interaction with analytes. Thus, these electrospun nanofiber-based glucose sensors present a number of advantages, including increased life time, which is greatly needed for practical applications. Taking all these facts into consideration, we have highlighted the latest significant developments in the field of glucose sensors across diverse approaches.
TL;DR: An electrochemical sensor based on molecularly imprinted polymer (MIP) nanoparticles for selective and sensitive determination of diazinon (DZN) pesticides was developed and showed that the carbon paste electrode modified by MIP nanoparticles (nano-MIP-CP) has much higher adsorption ability for d Diazinon than the CPE based non-imprinted polymer nanoparticles.
Abstract: In this research, an electrochemical sensor based on molecularly imprinted polymer (MIP) nanoparticles for selective and sensitive determination of diazinon (DZN) pesticides was developed. The nanoparticles of diazinon imprinted polymer were synthesized by suspension polymerization and then used for modification of carbon paste electrode (CPE) composition in order to prepare the sensor. Cyclic voltammetry (CV) and square wave voltammetry (SWV) methods were applied for electrochemical measurements. The obtained results showed that the carbon paste electrode modified by MIP nanoparticles (nano-MIP-CP) has much higher adsorption ability for diazinon than the CPE based non-imprinted polymer nanoparticles (nano-NIP-CP). Under optimized extraction and analysis conditions, the proposed sensor exhibited excellent sensitivity (95.08 μA L μmol(-1)) for diazinon with two linear ranges of 2.5 × 10(-9) to 1.0 × 10(-7) mol L(-1) (R (2) = 0.9971) and 1.0 × 10(-7) to 2.0 × 10(-6) mol L(-1) (R (2) = 0.9832) and also a detection limit of 7.9 × 10(-10) mol.L(-1). The sensor was successfully applied for determination of diaznon in well water and apple fruit samples with recovery values in the range of 92.53-100.86 %. Graphical abstract Procedure for preparation of electrochemical sensor based on MIP nanoparticles for determination of diazinon.
TL;DR: The present study confirms the increasing diffusion of new designer drugs with enhanced stimulant activity among the target population of poly-abuse consumers.
Abstract: The detection of new psychoactive substances (NPS) in hair proved to provide insight into their current diffusion among the population and the social characteristics of these synthetic drugs' users. Therefore, a UHPLC-MS/MS method was developed in order to determine 31 stimulant and psychedelic substituted phenethylamines, and dissociative drugs in hair samples. The method proved to be simple, fast, specific, and sensitive. The absence of matrix interferents, together with excellent repeatability of both retention times and relative abundances of diagnostic transitions, allowed the correct identification of all analytes tested. The method showed optimal linearity in the interval 10-1000 pg/mg, with correlation coefficient values varying between 0.9981 and 0.9997. Quantitation limits ranged from 1.8 pg/mg for 4-methoxyphencyclidine (4-MeO-PCP) up to 35 pg/mg for 6-(2-aminopropyl)benzofuran (6-APB). The method was applied to (i) 23 real samples taken from proven MDMA and ketamine abusers and (ii) 54 real hair samples which had been previously tested negative during regular drug screening in driver's license recovery. Six samples tested positive for at least one target analyte. Methoxetamine (MXE) was found in three cases (range of concentration 7.7-27 pg/mg); mephedrone (4-MMC) was found in two cases (50-59 pg/mg) while one sample tested positive for methylone at 28 pg/mg. Other positive findings included 4-methylethcathinone (4-MEC), alpha-pyrrolidinovalerophenone (α-PVP), 4-fluoroamphetamine (4-FA), 3,4-methylenedioxypyrovalerone (MDPV), and diphenidine. The present study confirms the increasing diffusion of new designer drugs with enhanced stimulant activity among the target population of poly-abuse consumers.
TL;DR: This study is the first to report and demonstrate the presence of dissolved cerium in plant seedling shoots exposed to CeO2NPs hydroponically, and the extent of plant uptake and accumulation appears to be dependent on the plant species.
Abstract: Cerium dioxide nanoparticles (CeO2NPs) are among the most broadly used engineered nanoparticles that will be increasingly released into the environment. Thus, understanding their uptake, transportation, and transformation in plants, especially food crops, is critical because it represents a potential pathway for human consumption. One of the primary challenges for the endeavor is the inadequacy of current analytical methodologies to characterize and quantify the nanomaterial in complex biological samples at environmentally relevant concentrations. Herein, a method was developed using single particle-inductively coupled plasma-mass spectrometry (SP-ICP-MS) technology to simultaneously detect the size and size distribution of particulate Ce, particle concentration, and dissolved cerium in the shoots of four plant species including cucumber, tomato, soybean, and pumpkin. An enzymatic digestion method with Macerozyme R-10 enzyme previously used for gold nanoparticle extraction from the tomato plant was adapted successfully for CeO2NP extraction from all four plant species. This study is the first to report and demonstrate the presence of dissolved cerium in plant seedling shoots exposed to CeO2NPs hydroponically. The extent of plant uptake and accumulation appears to be dependent on the plant species, requiring further systematic investigation of the mechanisms.
TL;DR: The microsensor principle is compared with other methods applied in biomedical research to show advantages and drawbacks, and different concepts to reject interfering substances by additional membranes, aspects of instrumentation and biocompatibility are examined.
Abstract: Miniaturized electrochemical in vivo biosensors allow the measurement of fast extracellular dynamics of neurotransmitter and energy metabolism directly in the tissue. Enzyme-based amperometric biosensing is characterized by high specificity and precision as well as high spatial and temporal resolution. Aside from glucose monitoring, many systems have been introduced mainly for application in the central nervous system in animal models. We compare the microsensor principle with other methods applied in biomedical research to show advantages and drawbacks. Electrochemical sensor systems are easily miniaturized and fabricated by microtechnology processes. We review different microfabrication approaches for in vivo sensor platforms, ranging from simple modified wires and fibres to fully microfabricated systems on silicon, ceramic or polymer substrates. The various immobilization methods for the enzyme such as chemical cross-linking and entrapment in polymer membranes are discussed. The resulting sensor performance is compared in detail. We also examine different concepts to reject interfering substances by additional membranes, aspects of instrumentation and biocompatibility. Practical considerations are elaborated, and conclusions for future developments are presented. Graphical Abstract ᅟ.
TL;DR: This approach shows promise for immediate practical use in the field to predict the TSD with a high degree of accuracy and demonstrates that Raman spectroscopy can be used as a nondestructive analytical tool for discriminating between bloodstains on the scale of hours to days.
Abstract: Knowing the time since deposition (TSD) of an evidentiary bloodstain is highly desired in forensics, yet it can be extremely complicated to accurately determine in practice. Although there have been numerous attempts to solve this problem using a variety of different techniques, currently, no established, well-accepted method exists. Here, a Raman spectroscopic approach was developed for determining the age of bloodstains up to 1 week old. Raman spectroscopy, along with two-dimensional correlation spectroscopy (2D CoS) and statistical modeling, was used to analyze fresh bloodstains at ten time points under ambient conditions. The 2D CoS results indicate a high correlation between several Raman bands and the age of a bloodstain. A regression model was built to provide quantitative predictions of the TSD, with cross-validated root mean squared error and R (2) values of 0.13 and 0.97, respectively. It was determined that a "new" (1 h) bloodstain could be easily distinguished from older bloodstains, which is very important for forensic science in helping to establish the relevant association of multiple bloodstains. Additionally, all bloodstains were confirmatively identified as blood by comparing the experimentally measured spectra to multidimensional body fluid spectroscopic signatures of blood, saliva, semen, sweat, and vaginal fluid. These results demonstrate that Raman spectroscopy can be used as a nondestructive analytical tool for discriminating between bloodstains on the scale of hours to days. This approach shows promise for immediate practical use in the field to predict the TSD with a high degree of accuracy. Graphical Abstract Bloodstain aging over time illustrating naturally ocurring processes.
TL;DR: LC-MS/HRMS allows resolution of variable stable isotopes incorporated into acyl-CoAs, enabling simultaneous quantitation and metabolic tracing and will allow highly precise, multiplexed, and stable isotope-resolved determination of metabolism to refine metabolic models, characterize novel metabolism, and test modulators of metabolic pathways involving acyl.
Abstract: Acyl-coenzyme A (acyl-CoA) thioesters are evolutionarily conserved, compartmentalized, and energetically activated substrates for biochemical reactions. The ubiquitous involvement of acyl-CoA thioesters in metabolism, including the tricarboxylic acid cycle, fatty acid metabolism, amino acid degradation, and cholesterol metabolism highlights the broad applicability of applied measurements of acyl-CoA thioesters. However, quantitation of acyl-CoA levels provides only one dimension of metabolic information and a more complete description of metabolism requires the relative contribution of different precursors to individual substrates and pathways. Using two distinct stable isotope labeling approaches, acyl-CoA thioesters can be labeled with either a fixed [(13)C3(15)N1] label derived from pantothenate into the CoA moiety or via variable [(13)C] labeling into the acyl chain from metabolic precursors. Liquid chromatography-hybrid quadrupole/Orbitrap high-resolution mass spectrometry using parallel reaction monitoring, but not single ion monitoring, allowed the simultaneous quantitation of acyl-CoA thioesters by stable isotope dilution using the [(13)C3(15)N1] label and measurement of the incorporation of labeled carbon atoms derived from [(13)C6]-glucose, [(13)C5(15)N2]-glutamine, and [(13)C3]-propionate. As a proof of principle, we applied this method to human B cell lymphoma (WSU-DLCL2) cells in culture to precisely describe the relative pool size and enrichment of isotopic tracers into acetyl-, succinyl-, and propionyl-CoA. This method will allow highly precise, multiplexed, and stable isotope-resolved determination of metabolism to refine metabolic models, characterize novel metabolism, and test modulators of metabolic pathways involving acyl-CoA thioesters.
TL;DR: It is demonstrated that the CCS database can also help to distinguish between isobaric structures exemplified for cyclophosphamide and ifosfamide.
Abstract: Non-target analysis has become an important tool in the field of water analysis since a broad variety of pollutants from different sources are released to the water cycle. For identification of compounds in such complex samples, liquid chromatography coupled to high resolution mass spectrometry are often used. The introduction of ion mobility spectrometry provides an additional separation dimension and allows determining collision cross sections (CCS) of the analytes as a further physicochemical constant supporting the identification. A CCS database with more than 500 standard substances including drug-like compounds and pesticides was used for CCS data base search in this work. A non-target analysis of a wastewater sample was initially performed with high performance liquid chromatography (HPLC) coupled to an ion mobility-quadrupole-time of flight mass spectrometer (IM-qTOF-MS). A database search including exact mass (±5 ppm) and CCS (±1 %) delivered 22 different compounds. Furthermore, the same sample was analyzed with a two-dimensional LC method, called LC+LC, developed in our group for the coupling to IM-qTOF-MS. This four dimensional separation platform revealed 53 different compounds, identified over exact mass and CCS, in the examined wastewater sample. It is demonstrated that the CCS database can also help to distinguish between isobaric structures exemplified for cyclophosphamide and ifosfamide.
TL;DR: An intelligentized strategy by ultra-high performance hydrophilic interaction chromatography/quadrupole time-of-flight mass spectrometry (HILIC/QTOF-MSE) is presented, used for the ESMs characterization and differentiation of two geographic origins of earthworm as a case study.
Abstract: Animal-derived medicines have been a vital component for traditional Chinese medicine. However, their quality control remains challenging due to the large polarity of the contained endogenous small molecules (ESMs) that are difficult to separate by reversed-phase HPLC. Herein, an intelligentized strategy by ultra-high performance hydrophilic interaction chromatography/quadrupole time-of-flight mass spectrometry (HILIC/QTOF-MSE) is presented, and used for the ESMs characterization and differentiation of two geographic origins of earthworm (Guang Di-long, GD; Hu Di-long, HD) as a case study. Chromatographic separation was performed on a BEH Amide column (2.1 × 100 mm, 1.7 μm). The MSE data in both negative and positive ion modes were acquired to record the high-accuracy MS and MS/MS data of all precursor ions. Automatic data processing was enabled by use of Progenesis QI software. As a consequence, 926 metabolites among 4705 features and 761 among 3418 features were characterized in the negative and positive modes, respectively, by searching the human metabolome database (HMDB). To reduce the false positive identifications, structural confirmation was conducted by comparison with the reference standards (tR and MS, MS/MS data) or matching with theoretical data or commercial library. Principal component analysis (PCA) of the GD and HD samples showed distinct classifications. Further orthogonal partial least squares discriminant analysis (OPLS-DA) and variable importance in projection (VIP) plot revealed the potential discriminatory markers between GD and HD. The present study provides a powerful and practical strategy that facilitates the primary metabolites characterization and quality evaluation of animal-derived medicines more efficiently.
TL;DR: This review focuses primarily on analytical methods for BPA detection that have emerged in recent years including sample pre-treatment and analytical methods used in the detection of bisphenol A.
Abstract: Bisphenol A (BPA) is an important industrial chemical used as a plasticizer in polycarbonate and epoxy resins in the plastic and paper industries. Because of its estrogenic properties, BPA has attracted increasing attention from many researchers. This review focuses primarily on analytical methods for BPA detection that have emerged in recent years. We present and discuss the advantages and disadvantages of sample preparation techniques (e.g., solvent extraction, solid-phase extraction, molecularly imprinted polymer solid-phase extraction, and micro-extraction techniques) and analytical methods (e.g., liquid chromatography, liquid chromatography−mass spectrometry, gas chromatography−mass spectrometry, capillary electrophoresis, immunoassay, and several novel sensors). We also discuss expected future developments for the detection of BPA.
TL;DR: Current paradigms of LA–ICPMS imaging are examined and how newly developed LA cell technology combined with simultaneous ICPMS instrumentation is poised to overcome current instrumental limitations to deliver faster, higher resolution elemental imaging is discussed.
Abstract: We describe trends in fast, high resolution elemental imaging by laser ablation-inductively coupled plasma mass spectrometry (LA-ICPMS). Recently developed low dispersion LA cells deliver quantitative transport of ablated aerosols within 10 ms and also provide enhanced sensitivity compared to conventional LA cells because the analyte ion signal becomes less diluted during aerosol transport. When connected to simultaneous ICPMS instruments, these low dispersion LA cells offer a platform for high speed and high lateral resolution shot-resolved LA-ICPMS imaging. Here, we examine the current paradigms of LA-ICPMS imaging and discuss how newly developed LA cell technology combined with simultaneous ICPMS instrumentation is poised to overcome current instrumental limitations to deliver faster, higher resolution elemental imaging.
TL;DR: It is shown that HILIC sorbents having highly orthogonal selectivity and specificity enhance the coverage of major metabolite groups in (semi-) targeted applications compared to RP, and fast and highly reproducible separations on zwitterionic columns are demonstrated.
Abstract: Liquid chromatography-mass spectrometry-based metabolomics studies require highly selective and efficient chromatographic techniques. Typically employed reversed-phase (RP) methods fail to target polar metabolites, but the introduction of hydrophilic interaction liquid chromatography (HILIC) is slow due to perceived issues of reproducibility and ruggedness and a limited understanding of the complex retention mechanisms. In this study, we present a comparison of the chromatographic performance of a traditional RP-C18 column with zwitterionic, amide-, alkyl diol-, and aminoalkyl-based HILIC and mixed-mode columns. Our metabolite library represents one of the largest analyte sets available and consists of 764 authentic metabolite standards, including amino acids, nucleotides, sugars, and other metabolites, representing all major biological pathways and commonly observed exogenous metabolites (drugs). The coverage, retention patterns, and selectivity of the individual methods are highly diverse even between conceptually related HILIC methods. Furthermore, we show that HILIC sorbents having highly orthogonal selectivity and specificity enhance the coverage of major metabolite groups in (semi-) targeted applications compared to RP. Finally, we discuss issues encountered in the analysis of biological samples based on the results obtained with human plasma extracts. Our results demonstrate that fast and highly reproducible separations on zwitterionic columns are feasible, but knowledge of analyte properties is essential to avoid chromatographic bias and exclusion of key analytes in metabolomics studies. Graphical Abstract The chromatographic parameters of 764 authentic metabolite standards provide the basis for a comparison of coverage, selectivity and orthogonality of 7 reversed-phase (RP), mixed-mode (MM) and hydrophilic interaction liquid chromatography (HILIC) methods.