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Nanospray desorption electrospray ionization (nano-DESI) is one of the ambient desorption ionization methods for mass spectrometry (MS), and it utilizes a steady-state liquid junction formed between two microcapillaries to directly extract analytes from sample surfaces with minimal sample damage. In this study, we employed nano-DESI MS to perform a metabolite fingerprinting analysis directly from a Hypericum leaf surface. Moreover, we investigated whether changes in metabolite fingerprints with time can be related to metabolite distribution according to depth. From a raw Hypericum leaf, the mass spectral fingerprints of key metabolites, including flavonoids and prenylated phloroglucinols, were successfully obtained using ethanol as a nano-DESI solvent, and the changes in their intensities were observed with time via full mass scan experiments. In addition, the differential extraction patterns of the obtained mass spectral fingerprints were clearly visualized over time through selected ion monitoring and pseudo-selected reaction monitoring experiments. To examine the correlation between the time-dependent changes in the metabolite fingerprints and depth-wise metabolite distribution, we performed a nano-DESI MS analysis against leaves whose surface layers were removed multiple times by forming polymeric gum Arabic films on their surfaces, followed by detaching. The preliminary results showed that the changes in the metabolite fingerprints according to the number of peelings showed a similar pattern with those obtained from the raw leaves over time. [ABSTRACT FROM AUTHOR]

Sulfite, a widely used food additive, is subject to regulated labeling. The extraction of sulfite as the stable hydroxymethylsulfonate (HMS) form and its quantitative analysis by liquid chromatography-tandem mass spectrometry (LC-MS/MS) has been recognized for their good sensitivity, selectivity, and versatility across various food materials. This study aimed to develop a cost-effective and simpler method for sulfite quantitation, while maintaining the superior sensitivity and selectivity of mass spectrometry (MS). To achieve this, we introduced paper spray ionization (PSI), an ambient desorption ionization technique that could achieve the direct measurement of analytes without employing separation. We also employed a novel internal standard (IS) structurally similar to the analyte, replacing the more expensive isotopically labeled IS. Although the PSI-MS/MS method developed in this study exhibited slightly lower analytical performance compared to the conventional LC-MS/MS, it remained effective for sulfite analysis in dried fruits. [ABSTRACT FROM AUTHOR]

Paper spray ionization (PSI) is an extractive ambient ionization technique for mass spectrometry (MS), whereby a triangular paper tip serves as the sampling base and the electrospray tip. During PSI, analytes are extracted and transported to the edge of the paper tip by the applied spraying solvent. Analytes can be purified from a sample matrix and separated from each other by this transportation process. In this study, we investigated and utilized the analyte transportation process of PSI for the in situ separation and analysis of lipid mixtures. We found that differential transport of phosphatidylcholine (PC) and triacylglycerol (TAG), the two most abundant lipid classes in animals, occurred during PSI. We also found that the order in which these lipids moved strongly depended on how the spraying solvent was applied to the paper base. The more polar PC moved faster than the less polar TAG during PSI, when a polar solvent was slowly fed into a paper tip, whereas TAG was transported faster than PC when excess solvent was applied to the tip at once. In addition, we achieved a complete separation and detection of PC and TAG by slowly supplying a nonpolar solvent to a PSI tip. [ABSTRACT FROM AUTHOR]

Paper spray ionization mass spectrometry (PSI MS) has emerged as a notable method for the rapid analysis of biological samples. However, the typical cellulose-based paper tip is incompatible with protein detection due to the strong interaction between cellulose hydroxyl groups and proteins. In this study, we utilized a commercially available polyolefin-based synthetic paper, Teslin®, as an alternative PSI substrate for simple protein analysis. We have named this method "droplet PSI" MS, as the aqueous protein solution droplet retains its shape on the Teslin® paper tip. For droplet PSI, no further chemical pretreatment was necessary for the Teslin® substrate; the only required preparation was shaping the Teslin® paper into a triangular tip. In droplet PSI MS, protein ion signals were instantly detected from a protein solution droplet upon applying a spray solvent in situ along with high voltage (HV). When compared with conventional PSI MS, our method demonstrated superior sensitivity. The droplet PSI MS utilizing Teslin® also showcased flexibility in real-time observation of protein alterations induced by an acid additive. Additionally, the effects of spray solvent composition and the application method were discussed. [ABSTRACT FROM AUTHOR]

Antibiotics in environment can be of concern as they can enter the food chain posing risks to ecosystems and human health. Photodegradation has been considered as a promising way of naturally degrading antibiotics in environment. Antibiotics are usually present in mixtures in environment; however, previous studies focused on individual compounds. Therefore, this study investigated the effect of UV irradiation on the degradation of tetracycline (TC) and sulfathiazole (STH) in individual solutions and mixtures. Under dark conditions, the initial masses of TC and STH were reduced by about 35% and 26%, respectively, over a 35 d-reaction period. With UV irradiation TC and STH were completely removed within 14 d and 35 d, respectively, regardless of the initial concentrations. Both the TC and STH removals were faster (i.e., 2–4 times) when they were in mixtures. This may be partly attributed to the byproducts such as sulfate that can promote indirect photolysis and partly to the enhanced hydrolysis due to changes in the solution pH. Overall, this study suggests that when photodegradation is used to remove antibiotics in water, the removal kinetics of antibiotics individually and in mixtures can be considered to develop more efficient treatment technologies. [ABSTRACT FROM AUTHOR]

Phenols are significant environmental endocrine disruptors that can have adverse health effects on exposed individuals. Correlating phenol exposure to potential health implications requires the development of a comprehensive and sensitive analytical method capable of analyzing multiple phenols in a single sample preparation and analytical run. Currently, no such method is available for multiple classes of phenols due to electrospray ionization (ESI) limitations in concurrent ionization and lack of sensitivity to certain phenols, particularly alkylphenols. In this study, we investigated the influence of mobile phase compositions in ESI on concurrent ionization and analytical sensitivity of liquid chromatography–electrospray ionization–tandem mass spectrometry (LC–ESI–MS/MS) during the analysis of multiple classes of phenols, and we propose a comprehensive and sensitive analytical method for various classes of phenols (i.e., bisphenols, parabens, benzophenones, chlorophenols, and alkylphenols). The proposed method was affected by 0.5 mM ammonium fluoride under methanol conditions. It enabled the concurrent ionization of all the phenols and significantly improved the analytical sensitivity for bisphenols and alkylphenols, which typically have poor ionization efficiency. This method, combined with a "dilute and shoot" approach, allowed us to simultaneously quantify 38 phenols with good chromatographic behavior and sensitivity. Furthermore, the method was successfully applied to the analysis of 61 urine samples collected from aquatic (swimming) and land (indoor volleyball and outdoor football) athletes. • Fluoride-assisted LC–ESI–MS/MS method to determine multiclass phenols in urine. • Ammonium fluoride and methanol as a phenol-specialized mobile-phase composition. • Dramatic sensitivity enhancement of alkylphenols and bisphenols by fluoride ions. • Fast, simple and practical sample preparation without uncontrolled sample loss. • Successful application to 61 urine samples from athletes. [ABSTRACT FROM AUTHOR]

Environmental pollutants (EPOLs), such as phthalates, volatile organic compounds, phenols, parabens, polycyclic aromatic hydrocarbons, pyrethroids, and environmental tobacco smoke, are highly heterogeneous compounds. Recently, attention has been drawn to the assessment of the combinatory effects of multiple EPs. To correlate multiple exposures with potential health implications, advanced comprehensive analytical methods covering multiclass EPOLs are essential. However, because of several technical problems associated with enzyme hydrolysis, simultaneous extraction, and multiresidue liquid chromatography–tandem mass spectrometry analysis, it is difficult to establish a comprehensive method covering a number of EPOLs in a single sample preparation and analytical run. We developed tandem hybrid hydrolysis, modified direct injection, and a comprehensive mobile phase to overcome these technical problems and established a comprehensive analytical method for simultaneous biomonitoring of multiclass EPOLs. Tandem hybrid hydrolysis using β-glucuronidase and consecutive acid hydrolysis allowed selective hydrolysis of glucuronide- and sulfate-conjugated metabolites without phthalate degradation. The comprehensive mobile phase composed of 0.01% acetic acid and acetonitrile enabled us to simultaneously analyze 86 EPOLs, with good chromatographic behavior and ionization efficiency. Modified direct injection allowed a small amount of sample and simultaneous urinary extraction. The method was validated and applied to 39 urine samples from 19 mother–newborn pairs for multiple exposure assessment. Results showed that BP-3, a general component in sunblock products, and monoethyl phthalate, a metabolite of diethyl phthalate, exhibit a clear positive correlation between mothers and newborns. Therefore, the developed method has potential as a novel analytical tool for long-term, large-scale, and data-rich human biomonitoring of EPOLs. • Comprehensive LC–ESI/MS/MS method for multiclass environmental pollutants. • Tandem hybrid hydrolysis and direct injection method without extraction. • Comprehensive mobile phase composition consisted of 0.01% acetic acid. • Analytical tool suitable for large-scale human biomonitoring. [ABSTRACT FROM AUTHOR]

Many studies have analyzed nicotine metabolites in blood and urine to determine the toxicity caused by smoking, and assess exposure to cigarettes. Recently, hair and nails have been used as alternative samples for the evaluation of smoking, as not only do they reflect long-term exposure but they are also stable and easy to collect. Liquid-liquid or solid-phase extraction has mainly been used to detect nicotine metabolites in biological samples; however, these have disadvantages, such as the use of toxic organic solvents and complex pretreatments. In this study, a modified QuEChERS method was proposed for the first time to prepare samples for the detection of nicotine metabolite cotinine (COT) and trans-3′-hydroxycotinine (3-HCOT) in hair and nails. High-performance liquid chromatography–tandem mass spectrometry (LC–MS/MS) was used to analyze traces of nicotine metabolites. The established method was validated for selectivity, linearity, lower limit of quantitation, accuracy, precision and recovery. In comparison with conventional liquid-liquid extraction (LLE), the proposed method was more robust, and resulted in higher recoveries with favorable analytical sensitivity. Using this method, clinical samples from 26 Korean infants were successfully analyzed. This method is expected to be applicable in the routine analysis of nicotine metabolites for environmental and biological exposure monitoring. [ABSTRACT FROM AUTHOR]