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Nowadays, the trend towards more compact, smarter and simpler devices is generally recognized as one of the most challenging aspects in the development of analytical instrumentation. Modern flow-based procedures do not escape this tendency. The level of integration and automation and the operational functionality of Multi-pumping flow systems (MPFS) would, in most of the situations, meet this requirement. The essential elements of MPFS are multiple solenoid actuated micro-pumps strategically positioned in the flow manifold, which are accountable for solutions insertion, propelling and commutation, conditioning the establishment and subsequent detection of the reaction zone. Being the only active components of the flow manifold they provide a great operational simplicity and assure a straightforward run-time control of important analytical variables. Moreover, the reduction of active components minimizes the probability of occurrence of equipment failures, malfunctions or errors. The low size and low cost of solenoid micro-pumps make them ideal tools to build up compact environmentally friendly analytical systems, which are characterized by low solutions consumptions and the minimisation of hazardous waste generation. Furthermore, the reproducible pulsed flowing stream produced by micro-pumps actuation has proven to be a valuable feature regarding sample/reagent mixing and reaction zone homogenisation. 相似文献
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A flow system designed with solenoid micro-pumps is proposed for fast and greener spectrophotometric determination of free glycerol in biodiesel. Glycerol was extracted from samples without using organic solvents. The determination involves glycerol oxidation by periodate, yielding formaldehyde followed by formation of the colored (3,5-diacetil-1,4-dihidrolutidine) product upon reaction with acetylacetone. The coefficient of variation, sampling rate and detection limit were estimated as 1.5% (20.0 mg L−1 glycerol, n = 10), 34 h−1, and 1.0 mg L−1 (99.7% confidence level), respectively. A linear response was observed from 5 to 50 mg L−1, with reagent consumption estimated as 345 μg of KIO4 and 15 mg of acetylacetone per determination. The procedure was successfully applied to the analysis of biodiesel samples and the results agreed with the batch reference method at the 95% confidence level. 相似文献
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The formation of the Mn(III)/EDTA complex in a flow system with solenoid micro-pumps was exploited for fast manganese determination in freshwater. Manganese(II) was oxidized in a solid-phase reactor containing lead dioxide immobilized on polyester. Long pathlength spectrophotometry was exploited to increase sensitivity, aiming to reach the threshold limit established by environmental legislation. A linear response was observed from 25 to 1500 μg L− 1, with a detection limit of 6 μg L− 1 (99.7% confidence level). Sample throughput and coefficient of variation were 36 samples/h and 2.6% (n = 10), respectively. EDTA consumption and waste generation were estimated as 500 μg and 3 mL per determination, respectively. The amount of Pb in the residue corresponds to 250 μg per determination and a solid-phase reactor could be used for up to 1600 determinations. Adsorption in active charcoal avoided interferences caused by organic matter and the developed procedure was successfully applied for determination of manganese in freshwater samples. Results were in agreement with those attained by GFAAS at the 95% confidence level. 相似文献
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Fábio R.P. Rocha Ángel Morales-Rubio Miguel de la Guardia 《Analytica chimica acta》2005,547(2):204-208
A flow system based on the multicommutation is proposed for fast and clean determination of cyclamate. The procedure exploits the reaction of cyclamate with nitrite in acidic medium and the spectrophotometric determination of the excess of nitrite by iodometry. The flow system was designed with a set of solenoid micro-pumps to minimize reagent consumption and waste generation. The detection limit was estimated as 30 μmol L−1 (99.7% confidence level) with linear response ranging up to 3.0 mmol L−1. The coefficient of variation was estimated as 1.7% for a solution containing 2.0 mmol L−1 cyclamate (n = 20). About 60 samples can be analyzed per hour, consuming only 3 mg KI and 1.3 μg NaNO2, and generating 2.0 mL of effluent per determination, thus providing an environmentally friendly alternative to previously proposed procedures. Common artificial and natural sweeteners did not interfere when present in concentrations 10-times higher than cyclamate. The procedure was successfully applied for determination of cyclamate in artificial table sweeteners with results in agreement with the reference method at the 95% confidence level. 相似文献
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(1) Pions produced in the development of extended atmospheric cosmic ray air showers subsequently decay to muons. The measured yield of those muons is generally underestimated by current phenomenological models and event generators optimized for cosmic ray physics. The importance of those disagreements motivates the feasibility studies for testing these models at the Large Hadron Collider (LHC) energies, at the highest center-of-mass energies achievable in a laboratory. The interaction of a nucleus and a virtual pion created in a charge exchange reaction at the LHC is a similar process to those contributing to the development of air showers in case of cosmic rays. The crucial problem of such an analysis is the selection of charge exchange events with the highest possible efficiency and high purity from proton–proton collisions at the LHC. (2) For this we consider distributions of various measurable quantities given by event generators commonly used in cosmic ray physics. (3) We examine the expected distributions of energy deposited in different calorimeters of an LHC experiment. We consider the geometrical acceptance and energy resolution of the detectors at the Compact Muon Solenoid (CMS) experiment, as an example. We determine a working point cut from the various options for event selection, and compare signal and background predictions using different models for a representative simple observable, such as average transverse momentum or charge particle yield. (4) A set of event selection cuts along these considerations is proposed, with the aim of achieving optimal efficiency and purity. 相似文献
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Vlasta Matijevi? 《Topology and its Applications》2010,157(17):2746-2756
We consider finite-sheeted covering maps from 2-dimensional compact connected abelian groups to Klein bottle weak solenoidal spaces, metric continua which are not groups. We show that whenever a group covers a Klein bottle weak solenoidal space it covers groups as well, moreover it covers the product of two solenoids. The converse is not true, we give an example of group which covers groups with any finite number of sheets, but does not cover any Klein bottle weak solenoidal space. 相似文献
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