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Background: Phospholipids (PLs) are major constituents of cell membranes, play important roles in cell proliferation and death, as well as in signal transduction, and therefore are relevant biomarkers for different pathologies. On the other hand, when the analysis of small compounds, such as therapeutics in blood is desired, then phospholipids are part of the matrix and cause serious interference during analysis. Currently, both the analysis and removal of PLs from biological samples are limited by extensive sample preparation and instrumental separation., Results: A fast and simple quantitative Ti 4+ -modified paper spray tandem mass spectrometric (TiPS-MS/MS) method was established in urine, where the enrichment of phospholipids was achieved, as well as reduction of matrix effects (primarily caused by high salt content) that ultimately led to improved sensitivity and selectivity. The method could achieve a physiologically relevant limit of detection (0.01-0.03 μg mL -1 ). Also, the usefulness of the Ti 4+ -modified paper was investigated in the opposite mode, namely for the selective removal of phospholipids from matrices such as plasma. Clonidine is used as model compound, as the detection of this compound is known to suffer from ion suppression by phospholipids. Compared with blank paper spray tandem mass spectrometry, the limit of detection could be improved from 0.3 μg mL -1 to 0.03 μg mL -1 by employing a Ti 4+ -modified paper on top of the spray tip to capture phospholipids from the sample., Significance and Novelty: A novel Ti 4+ -modified paper was developed to allow for rapid solid-phase extraction of phospholipids from urine or selective removal from plasma, followed by direct paper spray mass spectrometric detection as a fast and convenient sample preparation and analysis combination. The paper properties are based on the Ti 4+ metal ion, which can selectively bind phosphate-containing compounds under acidic conditions, and its applicability was demonstrated in relevant biological matrices., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier B.V.)

Chloride (Cl - ) is an inorganic anion present in a broad range of samples (e.g. biological, environmental, food, water, etc.), the determination of which is of widespread significance. In this work, we translate the well-established traditional argentometric method (Mohr's precipitation titration) into a small, simple, portable, and low-cost paper-based microfluidic diagnostic device, which provides rapid and quantitative analysis. The developed device enables the determination of chloride sample volumes as small as 5 μL. A distance-based detection method is implemented providing fully instrument-free quantitation. The beneficial effects of channel geometry (variable widths with constant heights) on analytical parameters were investigated. Trapezoidal channels (channel width changes linearly with height) were used to create a gradient of paper surface (titrant) available for the reaction, compared to the typical uniform rectangular channels (constant channel width). The trapezoid with increasing width offered higher sensitivity and lower detection limits (i.e. 0.05 mM vs 0.1 mM from the rectangular channel) for chloride determination across the concentration range of 0.05-25 mM. In addition, the effect of concentration of the deposited reagent on the obtained distance signals was investigated using varying concentrations of titrant (AgNO 3 ), which allowed determination of chloride across a wider dynamic range (up to 200 mM). The utility of the paper devices was demonstrated by determination of chloride in a variety of matrices including body fluids (sweat, serum, and urine) and water samples (drinking, mineral, river water)., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Background: Gas chromatography-ion mobility spectrometry (GC-IMS) is a powerful analytical technique which has gained widespread use in a variety of fields. Detecting peaks in GC-IMS data is essential for chemical identification. Topological data analysis (TDA) has the ability to record alterations in topology throughout the entire spectrum of GC-IMS data and retain this data in diagrams known as persistence diagrams. To put it differently, TDA naturally identifies characteristics such as mountains, volcanoes, and their higher-dimensional equivalents within the original data and measures their significance., Results: In the present contribution, a novel approach based on persistent homology (a flagship technique of TDA) is suggested for automatic 2D peak detection in GC-IMS. For this purpose, two different GC-IMS data examples (urine and olive oil) are used to show the performance of the proposed method. The outputs of the algorithm are GC-IMS chromatogram with detected peaks, persistence plot showing the importance (intensity) of the detected peaks and a table with retention times (RT), drift times (DT), and persistence scores of detected peaks. The RT and DT can be used for identification of the peaks and persistence scores for quantitation. Additionally, watershed segmentation is applied to the GC-IMS images to index individual peaks and segment overlapping compounds allowing for a more accurate identification and quantification of individual peaks., Significance: Inspection of the results for GC-IMS datasets showed the accurate and reliable performance of the proposed strategy based on persistent homology for automatic 2D GC-IMS peak detection for qualitative and quantitative analysis. In addition, this approach can be easily extended to other types of hyphenated chromatographic and/or spectroscopic data., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Background: The detection and quantification of urinary metabolites play an important role in disease diagnosis. In most cases, urinary analyses are done with liquid urine samples, which must be quickly transported to the laboratory to avoid metabolites degradation that is associated with temperature fluctuations. Consequently, dried sampling devices have emerged to minimize analyte degradation. However, most commercial dried sampling devices are expensive, aggregate low volumes, and need better analytical sensitivity. Therefore, a new dry urine sampling device that is inexpensive, suitable for domestic sampling operation, and efficient for quantifying metabolites without requiring high-resolution instruments is proposed in the present study., Results: The newly designed dry urine sampling device was produced by 3D printing that efficiently determines 63 urinary organic acids using liquid chromatography coupled with mass spectrometry (LC-MS/MS). The system's efficiency was demonstrated with analytical figures of merit, such as precision, accuracy, and stability of analytes after the sampling and storing of ordinary urine samples. The limits of quantification ranged from 0.01 to 0.42 ng mL-1. Precision and accuracy tests showed relative standard deviations of less than 15 %. The urine stability in the sampling device was high within seven days without any significant degradation of the metabolites. The method was applied to the analysis of 10 human urine samples and compared to a conventional method without the use of the sampling device. The results showed no statistically significant differences, demonstrating the method's efficiency., Significance: The proposed 3-D printing device was developed with fast, low-cost manufacturing features and can be manufactured with different volumetric capacities, adaptable to the needs of each user. Furthermore, it is innovative because this is the first sampling device that is effective for the simultaneous storage and preservation of several important urinary metabolites. Thus, it is anticipated that its application would contribute significantly to the identification of metabolic disorders., Competing Interests: Declaration of competing interest The authors declare that they are not aware of competing financial interests or personal relationships that could influence the work presented in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Analysis of dried urine spots (DUSs) is becoming an emerging technique in clinical, toxicological, and forensic chemistry due to the fully non-invasive collection, facile transportation, and simple storage of DUS samples. Correct DUS collection and elution is of the utmost importance because inadequate DUS sampling/processing may have direct consequences on quantitative DUS analyses and these aspects were, for the first time, comprehensively investigated in this contribution. Various groups of endogenous and exogenous species were selected as model analytes and their concentrations were monitored in DUSs collected on standard cellulose-based sampling cards. Strong chromatographic effects were observed for most analytes having a crucial impact on their distribution within the DUSs during sampling. Concentrations of target analytes were up to 3.75-fold higher in the central DUS sub-punch in comparison to the liquid urine. Consequently, substantially reduced concentrations of these analytes were determined in peripheral DUS sub-punches demonstrating that sub-punching, often applied to dried material spots, is not acceptable for quantitative DUS analyses. Hence, a simple, rapid, and user-friendly procedure was suggested, which employed an in-vial collection of a known urine volume on a pre-punched sampling disc (using a low-cost micropipette designed for patient-centric clinical sampling) and in-vial processing of the whole DUS. Excellent accuracy (0.20%) and precision (0.89%) of liquid transfers were achieved by the micropipette, which was also applied to remote DUS collection by laic and expert users. The resulting DUS eluates were analysed by capillary electrophoresis (CE) for the determination of endogenous urine species. The CE results demonstrated no significant differences between the two user groups, elution efficiencies of 88-100% (in comparison to the liquid urine), and precision better than 5.5%., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

In this study, an amphiphilic near-infrared fluorescent molecule (denoted BCPB) was employed as a fluorescent probe to detect free bilirubin. In an aqueous solution, the micellar assemblies of BCPB possess a strong excimer emission at 660 nm, which was dramatically quenched upon the addition of bilirubin. It has been proven that fluorescence quenching is mainly attributed to photoinduced electron transfer (PET) from BCPB to bilirubin. As a fluorescent probe of bilirubin, BCPB showed advantages, such as fast response (<1 min), good anti-interference ability, and low limit of detection (0.33 μmol L -1 , S/N = 3). BCPB was successfully applied to detect free bilirubin in human serum and urine, and the detection showed very high accuracy., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

The growing demand for a better understanding of the effects of chemical mixtures on human health has fostered the need for extensive estimation of uptake rates from identified sources and/or biomonitoring, which has encouraged the development of analyte- and matrix-independent analytical methods. In this paper, we report a comprehensive sample treatment platform for the efficient extraction and interference removal in the determination of twenty-one bisphenols and derivatives (log K ow from 1.254 to 6.564) in a variety of human exposure sources and biological fluids. Treatment of both liquid (canned beverages, urine and serum) and solid (canned food, dust) samples was based on the use of low volumes (190-200 μL) of a hexanol-based supramolecular solvent having properties of restricted access materials. The efficient extraction of bisphenol and derivatives (absolute recoveries 70-114%) was due to the mixed-mode mechanisms (hydrogen bonding, polar and dispersion interactions) and the huge number of binding sites offered by the supramolecular solvent with properties of restricted access materials for solute solubilization. Signal suppression or enhancement (SSE) values kept in the range 78-116% for samples encompassing a wide range of macromolecules content (e.g. protein, fat, carbohydrates, etc.). Quantification was carried out by liquid chromatography, electrospray tandem mass spectrometry using external calibration. Method quantitation limits for bisphenols in liquid and solid samples were in the interval 0.019-0.19 μg L -1 and 0.06-0.81 μg kg -1 . The method was applied to the determination of bisphenols and derivatives in thirteen human exposure sources and biological fluids. Only four bisphenols out of twenty-one were not found in the analyzed samples. This supramolecular solvent-based bisphenol- and matrix-independent method constitutes a valuable strategy in terms of analytical and operational characteristics for the assessment of human exposure to mixtures of bisphenols and derivatives., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Urinary 5-hydroxyindole-3-acetic acid (5-HIAA) is a marker for diagnosis of patients with carcinoid tumors. In clinical practice, a simple colorimetric assay has widely been utilized for urinary 5-HIAA via its reaction with 1-nitroso-2-naphthol (NNa) in nitrous acid medium. However, this colorimetric assay has been criticized for lack of specificity. Herein, we proposed a novel SERS-based method for selective detection of urinary 5-HIAA by the use of a modified nitrosonaphthol reaction, in which hydrochloric acid is substituted for nitric acid to control the reaction conditions. This slight modification is crucial to be able to detect the cationic products in the acidic reaction mixture, because the chloride-aggregated Ag colloids not only create enormous hot spots for SERS enhancement, but also improve the chemical stability of nanostructured Ag substrates in acidic environment. Under optimized conditions, the present method can detect 5-HIAA within 12 min at concentrations as low as 1.2 ng/mL, which is 1000 times lower than that of conventional colorimetric method. And more importantly, the present method exhibits specific response toward 5-HIAA against other metabolites with similar structures in the urine. The relative standard deviation (RSD) of the present method is less than 5%, suggesting the acceptable reproducibility. The recoveries ranging from 89.6% to 106.3% were obtained for spiked human urine samples with RSD of 3.7-4.9%. Furthermore, several healthy person's urine samples were also analyzed using the present method, and experimental results are in compliance with the levels recorded in a healthy population. On the basis of these results we can conclude that the present SERS-based method can provide a valuable alternative to conventional colorimetric assay for clinical diagnosis, evaluating prognosis, and monitoring of treatment in carcinoid tumors., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

The tunability of SELEX procedure is an essential feature to supply bioaffinity receptors (aptamers) almost on demand for analytical and therapeutic purposes. This longstanding ambition is, however, not straightforward. Non-invasive cancer diagnosis, so called liquid biopsy, requires collection of body fluids with minimal or no sample pretreatment. In those raw matrices, aptamers must recognize minute amounts of biomarkers that are not unique entities but large sets of variants evolving with the disease stage. The susceptibility of aptasensors to assay conditions has driven the selection of aptamers to natural environments to ensure their optimum performance in clinical samples. We present herein a compilation of the SELEX procedures in natural milieus. By revising the electrochemical aptasensors applied to clinical samples for cancer diagnosis and tracing back to the original SELEX we analyze whether aptamers raised using these SELEX strategies are being incorporated to the diagnostic devices and how aptasensors are finding their way to a market dominated by antibody-based assays., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

In this study, an electromembrane extraction-dispersive liquid-liquid microextraction (EME-DLLME) was performed using a lab-on-a-disc device. It was used for sample microextraction, preconcentration, and quantitative determination of tricyclic antidepressants as model analytes in biofluids. The disc consisted of six extraction units for six parallel extractions. First, 100 μL of a biofluid was used to extract the analytes by the drop-to-drop EME to clean-up the sample. The extraction then was followed by applying the DLLME method to preconcentrate the analytes and make them ready for being analyzed by gas chromatography (GC). Implementing the EME-DLLME method on a chip device brought some significant advantages over the conventional methods, including saving space, cost, and materials as well as low sample and energy consumption. In the designed device, centrifugal force was used to move the fluids in the disc. Both sample preparation methods were performed on the same disc without manual transference of the donor phases for doing the two methods. Scalable centrifugal force made it possible to adjust the injection speed of the organic solvent into the aqueous solution in the DLLME step by changing the spin speed. Spin speed of 100 rpm was used in dispersion step and spin speed of 3500 rpm was used to sediment organic phase in DLLME step. The proposed device provides effective and reproducible extraction using a low volume of the sample solution. After optimization of the effective parameters, an EME-DLLME followed by GC-MS was performed for determination of amitriptyline and imipramine in saliva, urine, and blood plasma samples. The method provides extraction recoveries and preconcentration factors in the range of 43%-70.8% and 21.5-35.5 respectively. The detection limits less than 0.5 μg L -1 with the relative standard deviations of the analysis which were found in the range of 1.9%-3.5% (n = 5). The method is suitable for drug monitoring and analyzing biofluids containing low levels of the model analytes., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

A methamphetamine-based molecularly imprinted polymer (MIP) has been prepared by bulk polymerization to recognize new psychoactive substances (NPS) of the amphetamine, cathinones and 2C families in oral fluid samples, being the first precedent of a synthetized MIP for the extraction and preconcentration 32 NPS including amphetamine type substances and synthetic cathinones from oral fluids. Pre-polymerization complex and resulting materials were appropriately characterized by infrared spectroscopy, scanning electron microscopy, and nitrogen adsorption-desorption isotherms. Appropriateness of the material for the specific recognition of the target analytes was also evaluated through computational calculations and experimentally assessed by solid phase extraction (SPE). The most appropriate SPE conditions were evaluated and recoveries of 32 different NPS were obtained, ranging from 80 to 120% with a relative standard deviation (RSD) in all cases lower than 12%. Amphetamine-related NPS were analyzed by a fast and portable methodology based on ion mobility spectrometry (IMS) and a rearguard procedure based on ultra-high performance liquid chromatography coupled to mass spectrometry (UHPLC-MS) providing limit of detection values from 10 to 80 μg L -1 and from 0.03 to 1.3 μg L -1 , respectively. Oral fluid samples, containing different interferents like caffeine, fluticasone and cetirizine, were spiked with 300 μg L -1 amphetamine and subsequently analyzed, showing recoveries ranging from 81 to 115% using both methodologies. Thus, this paper shows preliminary results to demonstrate the applicability of the developed procedure which could be used with minor modifications as screening technique in on-road drug analysis., (Copyright © 2018 Elsevier B.V. All rights reserved.)