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Per- and polyfluoroalkyl substances (PFASs) include persistent organic pollutants whose spread is still ubiquitous. Efforts to substitute substances of high concern with fluorinated alternatives, such as HFPO-DA (GenX), DONA (ADONA), and cC6O4, have been made. The aim of this work was to develop and validate an isotopic dilution liquid chromatography-tandem mass spectrometry (LC–MS/MS) method suitable to quantify 30 PFASs in human plasma. Analytes included legacy PFASs (PFOA, PFOS, and PFHxS), fluorinated alternatives (PFBA, PFBS, 6:2 FTSA, HFPO-DA, DONA, and cC6O4), and newly identified compounds (F-53B and PFECHS). The sample preparation was rapid and consisted of simple protein precipitation and centrifugation. Calibration standards and quality control solutions were prepared with a human pooled plasma containing relatively low background levels of the considered analytes. A complete validation was carried out: the lower limits of quantitation (LLOQs) ranged from 0.009 to 0.245 µg/L; suitable linearity (determination coefficients, R2 0.989–0.999), precision (2.0–19.5%, relative standard deviation), and accuracy (87.9–113.1% of theoretical) were obtained for considered concentration ranges. No significant variations of analyte responses were recorded under investigated storage conditions and during matrix effect tests. The external verification confirmed the accuracy of the method, although limited to 12 analytes. The method was also applied to 38 human plasma samples to confirm its applicability. The developed assay is suitable for large-scale analyses of a wide range of legacy and emerging PFASs in human plasma. To our knowledge, this is the first published method including cC6O4 for human biomonitoring.

cC6O4 is a new-generation perfluoroalkyl surfactant used in the chemical industry for the synthesis of perfluoroalkyl polymers. It was introduced as a less biopersistent substitute of traditional perfluoroalkyl surfactants such as PFOA, but its kinetics in humans was never investigated. This work is aimed to investigate the kinetics of elimination of cC6O4 in exposed workers. Eighteen male individuals occupationally exposed to cC6O4 in the production of fluoropolymers volunteered for the study. Blood and urine samples were collected from the end of a work-shift for the following 5 days off work. Serum and urinary cC6O4 were measured by LC-MS/MS. Seventy-two samples with serum cC6O4 ranging from 0.38 to 11.29 µg/L were obtained; mean levels were 3.07, 2.82, 2.67 and 2.01 µg/L at times 0, 18, 42 and 114 h. Two hundred and fifty-four urine samples with cC6O4 ranging from 0.19 to 5.92 µg/L were obtained. A random-intercept multiple regression model was applied to serum data and a half-life of 184 (95% CI 162–213) h for a first-order kinetics elimination was calculated; a mean distribution volume of 80 mL/kg was also estimated. Pearson’s correlation between ln-transformed serum and daily urine concentrations was good, with r ranging from 0.802 to 0.838. The amount of cC6O4 excreted daily in urine was about 20% of the amount present in serum. The study allowed calculating a half-life for cC6O4 in blood of about 8 days in humans, supporting its much shorter biopersistence in comparison with legacy PFAS. The good correlation between urine and serum cC6O4 suggests urine as a possible non-invasive matrix for biomonitoring. The amount of cC6O4 excreted daily in urine suggests urine as the sole elimination route.

cC O is a new-generation perfluoroalkyl surfactant used in the chemical industry for the synthesis of perfluoroalkyl polymers. It was introduced as a less biopersistent substitute of traditional perfluoroalkyl surfactants such as PFOA, but its kinetics in humans was never investigated. This work is aimed to investigate the kinetics of elimination of cC O in exposed workers. Eighteen male individuals occupationally exposed to cC O in the production of fluoropolymers volunteered for the study. Blood and urine samples were collected from the end of a work-shift for the following 5 days off work. Serum and urinary cC O were measured by LC-MS/MS. Seventy-two samples with serum cC O ranging from 0.38 to 11.29 µg/L were obtained; mean levels were 3.07, 2.82, 2.67 and 2.01 µg/L at times 0, 18, 42 and 114 h. Two hundred and fifty-four urine samples with cC O ranging from 0.19 to 5.92 µg/L were obtained. A random-intercept multiple regression model was applied to serum data and a half-life of 184 (95% CI 162-213) h for a first-order kinetics elimination was calculated; a mean distribution volume of 80 mL/kg was also estimated. Pearson's correlation between ln-transformed serum and daily urine concentrations was good, with r ranging from 0.802 to 0.838. The amount of cC O excreted daily in urine was about 20% of the amount present in serum. The study allowed calculating a half-life for cC O in blood of about 8 days in humans, supporting its much shorter biopersistence in comparison with legacy PFAS. The good correlation between urine and serum cC O suggests urine as a possible non-invasive matrix for biomonitoring. The amount of cC O excreted daily in urine suggests urine as the sole elimination route.

cC[sub.6] O[sub.4] is a new-generation perfluoroalkyl surfactant used in the chemical industry for the synthesis of perfluoroalkyl polymers. It was introduced as a less biopersistent substitute of traditional perfluoroalkyl surfactants such as PFOA, but its kinetics in humans was never investigated. This work is aimed to investigate the kinetics of elimination of cC[sub.6] O[sub.4] in exposed workers. Eighteen male individuals occupationally exposed to cC[sub.6] O[sub.4] in the production of fluoropolymers volunteered for the study. Blood and urine samples were collected from the end of a work-shift for the following 5 days off work. Serum and urinary cC[sub.6] O[sub.4] were measured by LC-MS/MS. Seventy-two samples with serum cC[sub.6] O[sub.4] ranging from 0.38 to 11.29 µg/L were obtained; mean levels were 3.07, 2.82, 2.67 and 2.01 µg/L at times 0, 18, 42 and 114 h. Two hundred and fifty-four urine samples with cC[sub.6] O[sub.4] ranging from 0.19 to 5.92 µg/L were obtained. A random-intercept multiple regression model was applied to serum data and a half-life of 184 (95% CI 162–213) h for a first-order kinetics elimination was calculated; a mean distribution volume of 80 mL/kg was also estimated. Pearson’s correlation between ln-transformed serum and daily urine concentrations was good, with r ranging from 0.802 to 0.838. The amount of cC[sub.6] O[sub.4] excreted daily in urine was about 20% of the amount present in serum. The study allowed calculating a half-life for cC[sub.6] O[sub.4] in blood of about 8 days in humans, supporting its much shorter biopersistence in comparison with legacy PFAS. The good correlation between urine and serum cC[sub.6] O[sub.4] suggests urine as a possible non-invasive matrix for biomonitoring. The amount of cC[sub.6] O[sub.4] excreted daily in urine suggests urine as the sole elimination route.

A hint of dark matter? Cosmic ray positrons are known to be produced in interactions in the interstellar medium. As well as originating from this 'secondary source', positrons might also be generated in primary sources such as pulsars and microquasars — or by dark matter annihilation. A new measurement of the positron fraction in the cosmic radiation for the energy range 1.5–100 GeV has been made using data from the PAMELA satellite experiment. Previous measurements, made predominantly by balloon-borne instruments, yield a positron fraction compatible with 'secondary source' production from interactions between cosmic ray nuclei and interstellar matter. Above 10 GeV the new measurements deviate significantly from this expectation, pointing to the presence of a primary source, either a nearby astrophysical object or dark matter particle annihilations. Cosmic ray positrons are known to be produced by interactions in the interstellar medium, but they might also originate in primary sources, such as pulsars, micro-quasars or through dark matter annihilation. Adriani et al . report that the positron fraction increases sharply over much of the energy range 1.5–100 GeV, which appears to be completely inconsistent with secondary sources—they therefore conclude that a primary source is necessary. Antiparticles account for a small fraction of cosmic rays and are known to be produced in interactions between cosmic-ray nuclei and atoms in the interstellar medium 1 , which is referred to as a ‘secondary source’. Positrons might also originate in objects such as pulsars 2 and microquasars 3 or through dark matter annihilation 4 , which would be ‘primary sources’. Previous statistically limited measurements 5 , 6 , 7 of the ratio of positron and electron fluxes have been interpreted as evidence for a primary source for the positrons, as has an increase in the total electron+positron flux at energies between 300 and 600 GeV (ref. 8 ). Here we report a measurement of the positron fraction in the energy range 1.5–100 GeV. We find that the positron fraction increases sharply over much of that range, in a way that appears to be completely inconsistent with secondary sources. We therefore conclude that a primary source, be it an astrophysical object or dark matter annihilation, is necessary.

Magnetic spectrometer PAMELA was launched onboard a satellite Resurs-DK1 into low-Earth polar orbit with altitude 350-600 km to study cosmic ray antiparticle fluxes in a wide energy range from ∼ 100 MeV to hundreds GeV. This paper presents the results of observations of temporal variations of the positron and electron fluxes in the 2006-2015. The ratio of the positron and electron fluxes below 2 GV shows sharp increasing since 2014 due to changing of the polarity of the solar magnetic field.

Measurements of electron and positron spatial distributions in energy range from 80 MeV to several GeV below the geomagnetic cutoff rigidity were carried out using the PAMELA magnetic spectrometer. The instrument is installed on board the Resurs-DK satellite which was launched June 15th 2006 on an elliptical orbit with the inclination 70 degrees and the altitude 350-600 km. The procedure of trajectories calculations in the geomagnetic filed gives a way to separate stably trapped and short lived albedo components produced in interactions of cosmic ray protons with the residual atmosphere. The work presents spatial distributions of trapped, quasitrapped and short-lived albedo electrons and positrons in the near Earth space. Electron to positron ratio points out on different production mechanism of trapped and quasitrapped particles.

In the framework of the PAMELA experiment the features of the large-scale anisotropy have been measured within the energy range 1-20 TeV/n. The measurements were carried out with the use of the calorimeter on the base of the hypothesis about the existence of a dipole anisotropy. The amplitude and phase of the dipole were obtained. The results are in agreement with the ground-based observations.

This paper presents precise measurements of the differential energy spectra of quasi‐trapped secondary electrons and positrons and their ratio between 80 MeV and 10 GeV in the near‐equatorial region (altitudes between 350 km and 600 km). Latitudinal dependences of the spectra are analyzed in detail. The results were obtained from July until November 2006 onboard the Resurs‐DK satellite by the PAMELA spectrometer, a general purpose cosmic ray detector system built around a permanent magnet spectrometer and a silicon‐tungsten calorimeter.