Study of analytical techniques to determine chlorpyrifos in the surface waterways of the rural zone of Ouro Branco, Brazil : a case study.

The presence of insecticides in the waterways of the municipality of Ouro Branco, MG, Southeastern Brazil, has become a public health problem. Recent research correlates the presence of these toxins in the water to the high indexes for hypertension and abortions occurring in the rural area. These insecticide residues are only slightly concentrated in the water, and as such, it is necessary to search for and optimize analytic methods that are capable of detecting these very low concentrations. To define the method that presents the best detectability for the organochlorine chlorpyrifos, one of the most used pesticides in the area, sample extraction techniques such as liquid?liquid extraction with low temperature partition (LLE-LTP) and headspace solid-phase microextraction (HS-SPME) were used, followed by gas chromatography analysis with electron capture detection (GC-ECD). Full factorial design 24 and the Doehlert matrix were used to optimize both extraction techniques. The results displayed that HS-SPME-GCECD was the method that presented the best performance for determining the presence of chlorpyrifos in the water. The optimum condition was defined at the extraction time and temperature of 60 min and 85 ?C, respectively, with a sample volume of 11 mL and Na2HPO4 concentration of 0.04 mol/L. The optimized method was validated for the principal figures of merit. The method displayed linearity with R2 equal to 0.992 and detection limit (LOD) and quantification limit (LOQ) of 0.50 and 1.67 ?g/L, respectively. The results indicate that the HS-SPME-GC-ECD technique proposed is efficient for determining the presence of chlorpyrifos in water, and analyses of the collected sample indicated the presence of chlorpyrifos in water bodies in the rural zone of Ouro Branco in concentrations within detection and quantification limits

The value of open-source clinical science in pandemic response: lessons from ISARIC

International audienc

Measurements of the Total and Differential Higgs Boson Production Cross Sections Combining the H??????? and H???ZZ*???4??? Decay Channels at s\sqrt{s}=8??????TeV with the ATLAS Detector

Measurements of the total and differential cross sections of Higgs boson production are performed using 20.3~fb$^{-1}$ of $pp$ collisions produced by the Large Hadron Collider at a center-of-mass energy of $\sqrt{s} = 8$ TeV and recorded by the ATLAS detector. Cross sections are obtained from measured $H \rightarrow \gamma \gamma$ and $H \rightarrow ZZ ^{*}\rightarrow 4\ell$ event yields, which are combined accounting for detector efficiencies, fiducial acceptances and branching fractions. Differential cross sections are reported as a function of Higgs boson transverse momentum, Higgs boson rapidity, number of jets in the event, and transverse momentum of the leading jet. The total production cross section is determined to be $\sigma_{pp \to H} = 33.0 \pm 5.3 \, ({\rm stat}) \pm 1.6 \, ({\rm sys}) \mathrm{pb}$. The measurements are compared to state-of-the-art predictions.Measurements of the total and differential cross sections of Higgs boson production are performed using 20.3  fb-1 of pp collisions produced by the Large Hadron Collider at a center-of-mass energy of s=8  TeV and recorded by the ATLAS detector. Cross sections are obtained from measured H→γγ and H→ZZ*→4ℓ event yields, which are combined accounting for detector efficiencies, fiducial acceptances, and branching fractions. Differential cross sections are reported as a function of Higgs boson transverse momentum, Higgs boson rapidity, number of jets in the event, and transverse momentum of the leading jet. The total production cross section is determined to be σpp→H=33.0±5.3 (stat)±1.6 (syst)  pb. The measurements are compared to state-of-the-art predictions.Measurements of the total and differential cross sections of Higgs boson production are performed using 20.3 fb$^{-1}$ of $pp$ collisions produced by the Large Hadron Collider at a center-of-mass energy of $\sqrt{s} = 8$ TeV and recorded by the ATLAS detector. Cross sections are obtained from measured $H \rightarrow \gamma \gamma$ and $H \rightarrow ZZ ^{*}\rightarrow 4\ell$ event yields, which are combined accounting for detector efficiencies, fiducial acceptances and branching fractions. Differential cross sections are reported as a function of Higgs boson transverse momentum, Higgs boson rapidity, number of jets in the event, and transverse momentum of the leading jet. The total production cross section is determined to be $\sigma_{pp \to H} = 33.0 \pm 5.3 \, ({\rm stat}) \pm 1.6 \, ({\rm sys}) \mathrm{pb}$. The measurements are compared to state-of-the-art predictions