Identification and assay of underivatized urinary acylcarnitines by paper spray tandem mass spectrometry.

A new analytical approach, using paper spray tandem mass spectrometry, has been developed for assay of carnitine and acylcarnitines in urine. Paper spray (PS) is a very promising technique, especially in clinical investigations, because of its simplicity, low cost, and rapid sample preparation. A home-made paper spray device was used for assay of urinary acylcarnitines (C2-C18). The performance of solvents with different elution efficiency and paper substrates with different porosity grade and structure were tested by use of spiked synthetic urine. Tandem mass spectrometry in multiple reaction monitoring (MRM) mode was optimized to obtain better specificity and sensitivity. Analyte signals were evaluated for stability and reproducibility. Calibration with [(2)H3]propionylcarnitine (C3-d3), [(2)H3]octanoylcarnitine (C8-d3), and [(2)H3] palmitoylcarnitine (C16-d3) as internal standards was used for quantification. Very good linearity was obtained, with correlation coefficients >0.99 for C0-C12 and C16 acylcarnitines and >0.96 for C14 and C18 acylcarnitines. Accuracy and precision (RSD, %) of the proposed procedure were tested at concentrations of 0.8, 8, and 20 mg L(-1) with very satisfactory results: overall mean accuracy was 98.9% and overall mean relative standard deviation 1%. Limits of detection (LOD) between 6 and 208 µg L(-1) for propionylcarnitine and tetradecanoylcarnitine, respectively, can be regarded as very satisfactory. Application of the method to real urine proved that paper spray tandem mass spectrometry is a simple, rapid, and direct tool (no derivatization is required) for assay of carnitine and C2-C12 acylcarnitines in urine.

Analytical study on the primary and secondary organic carbon and elemental carbon in the particulate matter at the high-altitude Monte Curcio GAW station, Italy.

This study provides a thorough investigation of the trends of organic carbon (OC) and elemental carbon (EC) in particulate matter (PM)10 and PM2.5 samples collected at the Monte Curcio Observatory (1780 m a.s.l.), a station of the Global Atmosphere Watch (GAW) program and Global Mercury Observation System (GMOS) network. Although the drawn attention toward these pollutants, there is still a lack of data for southern Italy, and this work is a contribution toward the filling of this gap. PM was sampled daily in 2016 and analyzed by thermo-optical transmittance method, while equivalent black carbon (eBC) concentrations in PM10 were simultaneously measured using a multiangle absorption photometer. The results showed that in PM10, the average values of OC and EC were 1.43 µgC/m3 and 0.12 µgC/m3, whereas in PM2.5, these concentrations were 1.09 µgC/m3 and 0.12 µgC/m3, respectively. We detected a clear seasonal variability in OC and EC with higher concentrations during the warm period. Moreover, the analysis of the OC/EC ratio revealed that most of the carbonaceous aerosol was transported by long-range air masses, as further confirmed by the use of the concentration-weighed trajectory (CWT) model. The mass absorption cross-section at 632 nm of EC (MACEC) over the entire period was 9.67 ± 4.86 m2/g and 8.70 ± 3.18 m2/g in PM2.5 and PM10, respectively, and did not exhibit a clear seasonal variation. The concentrations for OC and EC were also used for the computation of the secondary organic carbon (SOC) content, whose outcomes resulted in a seasonal trend similar to those obtained for OC and EC. As regards the eBC, its weekly pattern showed a slight increase during the weekend in the warm period, consistent with the anthropic activities in the touristic area surrounding the observatory.

Modification of the EPA method 1631E for the quantification of total mercury in natural waters.

To support the effectiveness of the Minamata Convention, the accurate determinations of mercury (Hg) in natural waters is an important but certainly challenging task due to the low concentrations expected in ambient samples. Mercury contamination may occur from many sources such as the unproperly-cleaning of storage bottles or the use of reagents for sample analysis with Hg traces, thus leading the analyst to easily run into errors. In our work, we propose some key modifications to the United States Environmental Protection Agency(EPA) method 1631E aimed at reducing the Hg contamination of reagents, storage containers, and minimizing the carryover effect in the instrumental line of sampling. The changes introduced have been tailored for the use of the method with cold vapor atomic fluorescence spectroscopy (CV-AFS) instrumentation and tested as part of a United Nations Environment Program (UNEP) ring test. Although the edited method was tested with natural water samples, the proposed method improvements can also apply to the Hg analysis in solid matrices that require the prior acid digestion of the samples.•A customized version of the EPA method 1631E is proposed for the analysis of aqueous samples.•New protocols for the reduction of contamination in the storage bottles and reagents used for the preparation of BrCl solution are provided.•A useful strategy for the control of the memory effect is included.

Electronic structure of MAPbI3 and MAPbCl3: importance of band alignment.

Since their first appearance, organic-inorganic perovskite absorbers have been capturing the attention of the scientific community. While high efficiency devices highlight the importance of band level alignment, very little is known on the origin of the strong n-doping character observed in the perovskite. Here, by means of a highly accurate photoemission study, we shed light on the energy alignment in perovskite-based devices. Our results suggest that the interaction with the substrate may be the driver for the observed doping in the perovskite samples.

A green approach for organophosphate ester determination in airborne particulate matter: Microwave-assisted extraction using hydroalcoholic mixture coupled with solid-phase microextraction gas chromatography-tandem mass spectrometry.

Particulate matter (PM) is among the most dangerous air pollutants, and there is a growing concern related to the effects of airborne particles on human health. Their harmful effects can be derived are directly linked to the size of particles themselves and the associated pollutants after they have been taken up by inhalation. In this work was developed a new analytical method for the quantification of organophosphorus esters (OPE) bound to airborne PM. The proposed protocol provides for the microwave-assisted extraction (MAE) of the analytes from the PM followed by solid-phase microextraction gas chromatography-tandem mass spectrometry determination (SPME-GC-MS/MS). Unlike to the traditional protocol, which provides for the use of tedious Soxhlet extraction with environmentally damaging organic solvents, the proposed method allows for a reliable quantification by using an eco-friendly hydroalcoholic mixture (water/ethanol; 50:50, v/v). The method was developed using as target compounds ten organophosphate esters, namely tripropyl phosphate (TPP), tri-n-butyl phosphate (TBP), tris(2-chloroethyl) phosphate (TCEP), tris(1-chloro-2-propyl) phosphate (TCPP), tris(1,3-dichloro-2-propyl) phosphate (TDCPP), tributoxyethyl phosphate (TBEP), triphenyl phosphate (TPhP), 2-ethylhexyl-diphenyl phosphate (EHDPP), tris(2-ethylhexyl) phosphate (TEHP) and tricresyl phosphate (TCP). The extraction performance of five SPME fibers was evaluated and the DVB/CAR/PDMS coating demonstrated to be the most suitable for the extraction of the target analytes. Experimental Design was used for the multivariate optimization of the parameters affecting the MAE process as well as the SPME extraction, and the optimal working conditions were determined by using Derringer's desirability function. The developed method was validated in terms of linearity, sensitivity (LLOQ values of 0.5 ng/mL for TDCPP and 0.1 ng/mL for the other analytes), matrix effect (81-117%), intra and inter day accuracy (83-115% and 80-115%, respectively), and precision (repeatability and reproducibility in the range 1.0-12.4% and 2.3-15.2%, respectively). The satisfactory performances reached make the proposed protocol a green and high-throughput alternative for OPE quantification in particulate matter.