Search results for "cura"

A new flow cell design for chemiluminiscence analysis.

2001

The present study proposes a new flow cell called a bundle cell for chemiluminescence analysis. The results obtained were compared with those achieved by manual and automated batch procedures and flow manifolds with different cells: an common quartz flow cell, a helix cell and the most used spiral cell. Figures of merit such as limit of detection, sensitivity, accuracy and precision for the Cr(III) determination were established with light emission produced by catalysed Cr(III) luminol oxidation by hydrogen peroxide in a basic aqueous solution. An improvement in sensitivity about 50% as compared with the spiral cell and even larger with respect to the other flow cells tested was observed. T…

Addition of thiourea and hydrochloric acid: Accurate nanogram level analysis of mercury in humic-rich natural waters by inductively coupled plasma ma…

2020

Abstract An analytical method was developed for the direct determination of total mercury in natural waters at low ng L−1 level by inductively coupled plasma mass spectrometry (ICP-MS). The presented method overcomes previously observed problems relating to poor spike recoveries by adding 0.12% thiourea in addition to 3% HCl to all samples and standards. The sample preparation is fast and easy to perform by the developed method since it requires only the addition of HCl and thiourea to the water samples. A very low instrument detection limit (0.4 ng L−1) was obtained without time-consuming preconcentration procedures. The accuracy and precision of the developed method were found excellent b…

Copper, iron and zinc determinations in human milk using FAAS with microwave digestion

2000

Abstract A method for determining copper, iron and zinc in human milk was optimized and validated. It includes microwave mineralization of the sample and measuring the elements by flame atomic absorption spectroscopy (FAAS). Only 2 ml of milk is needed, and the method is free of matrix interferences. The values obtained for the detection limits (0.07; 0.07; 0.11 μg/ml milk, for copper, iron and zinc) precision of the method, intra-assay (2.9; 5.2; 6.1%RSD for copper, iron and zinc) and accuracy, evaluated using recovery assays (98.8; 100.4; 95.9% for copper, iron and zinc) show that the method is useful for the purpose mentioned. Moreover, the method is rapid and simple, and the determinati…

Determination of methamphetamine in urine samples with sodium 1,2-naphthoquinone-4-sulphonate

1994

Optimal conditions have been studied for the determination of methamphetamine in urine samples by an extractive-spectrophotometric method with sodium 1,2-naphthoquinone-4-sulphonate (NQS) as reagent. These conditions are: NaHCO3 pH 10, NQS 6.3 × 10−3 mol/l and heating for 5 min at 45°C. The accuracy and precision of the method were tested. The detection limits were 0.2 mg/l in the standard and 0.9 mg/l when 5 ml of urine sample were taken. The standard deviation of blank urine was evaluated from 12 different samples. The relative errors found in the determination of methamphetamine in urine were lower than 10% if the methamphetamine-amphetamine ratio was higher than 4.

Influence of the differentiation system on the analytical parameters for the spectrophotometric determination of clonazepam in urine

1991

Abstract Electronic and mathematical differentiation of the ultraviolet visible spectra were compared from the study of the analytical parameters of the direct determination of clonazepam in urine samples. Third-order derivative spectra were used. The mathematical differentiation provides higher sensitivity, a lower limit of detection, and better accuracy and precision than the electronic one. The use of a diode array instrument provides lower sensitivity than that found using a conventional spectrometer; however, the limit of detection obtained in both cases is of the same order.

FI automatic method for the determination of copper(II) based on coproporphyrin I-Cu(II)/TCPO/H(2)O(2) chemiluminescence reaction for the screening o…

2004

Abstract In this paper, an automatic method for the screening of water samples containing Cu(II) was proposed, based on peryoxalate chemiluminescence reaction using coproporphyrin I as fluorophor compound to provide selectivity and a simple flow injection (FI) chemiluminescence detector (CLD). FI system conditions were chosen in order to distinguish samples over or under legislation limit established (50 μg l−1) with high reliability. The detection limit found was 9 μg l−1 and the linear dynamic range was 15–125 μg l−1 of Cu(II). Repeatibility and reproducibility studies gave good precision and accuracy with recovery near 100%. Under these conditions, the method resulted selective and only …

Diffuse Liver Diseases: Role of imaging

2018

Nowadays, the most common imaging techniques allow to study focal liver lesions with high diagnostic accuracy but a relatively recent emerging field of interest is represented by diffuse liver disease. They include a variegated series of storage and metabolic pathologies (ie, iron overload disorders and steatosis) requiring a precise diagnosis not always possible at imaging due to the overlapping of findings at conventional ultrasound, CT, or MR studies. In recent years, several imaging tecniques and specific softwares have been developed, especially for ultrasound and MR imaging, in order to identify different parameters useful in the noninvasive recognition and follow-up of these diffuse …

Small-x, Diffraction and Vector Mesons

2015

This talk discusses recent progress in some topics relevant for deep inelastic scattering at small x. We discuss first differences and similarities between conventional collinear factorization and the dipole picture of deep inelastic scattering. Many of the recent theoretical advances at small x are related to taking calculations in the nonlinear saturation regime to next-to-leading order accuracy in the QCD coupling. On the experimental side significant recent progress has been made in exclusive and diffractive processes, in particular in ultraperipheral nucleus-nucleus collisions.

Responsabilità giuridica e politica della Procura Europea nell'esercizio dell'azione penale e nello svolgimento delle indagini: l'asimmetria dei cont…

2018

HIGH-ORDER ACCURATE EMBEDDED-BOUNDARY DISCONTINUOUS GALERKIN METHODS FOR INVISCID GAS DYNAMICS

2022

This work presents a computational framework for solving the equations of inviscid gas dynamics over embedded geometries based on the discontinuous Galerkin (DG) method. The novelty of the framework is the ability to achieve high-order accuracy in the regions of smooth flow and to handle the presence of solution discontinuities via suitably introduced damping terms, which allow controlling spurious oscillations that are typical of high-order methods for first-order hyperbolic PDEs. The framework employs block structured Cartesian grids where a level set function defines implicitly the considered geometry. The domain is partitioned by intersecting the grid and the level set function, such th…