Analytical Method

The size distribution of polycyclic aromatic hydrocarbons (PAH) was determined for airborne particles from a large city with high vehicular traffic. The analytical method was optimised and validated using NIST standard reference material (SRM 1649a Urban Dust). The 16 priority PAH listed in the US-EPA were Soxhlet-extracted from filtered particulate matter and then fractionated using on-column chromatography. The aromatic fraction was quantified by gas chromatography-mass spectrometry. Real samples of particles collected in Seville (Spain) were analysed using the validated method. Values for the total concentration of PAH in the air, as well as the concentrations of each PAH in six particle-size ranges were obtained. Values of the PAH in TSP, PM10, PM2.5 and PM1 were assessed.

A reversed-phase high-performance thin-layer chromatographic method combined with image analysis was developed and validated for simultaneous quantitative evaluation of paracetamol and caffeine in pharmaceutical preparations. RP-HPTLC-W18 chromatographic plates were used as the stationary phase and methanol:glacial acetic acid:water (25:4.3:70.7; v:v:v) as the mobile phase. The detection of the spots and the image documentation were carried out under 254 nm UV radiation.

The purpose of the study was to optimise analytical methods for determination of the chemical speciation of mercury in studies of protective mechanisms of selenium. Optimisation of the methods was performed using CRM DOLT-2 (Dogfish liver), both in its original form and after separation of various fractions. The sample was homogenised with 10 mM Tris-HCl buffer (pH 7.6) and ultracentrifuged. The soluble phase obtained was applied to a size exclusion chromatography column (Sephadex G-75 column) for separation of various protein fractions. Total mercury (total Hg), monomethyl mercury (MeHg) and selenium (Se) were determined in whole dogfish liver tissue and its soluble and insoluble phases (pellet). Different approaches for determination of total Hg and MeHg were compared. Simultaneous determination of MeHg and inorganic mercury (Hg2+) was based on alkaline dissolution and/or acid leaching, followed by ethylation, room temperature precollection, isothermal gas chromatography (GC), pyr...

An accurate analytical interpretation method to determine the Leverett function (fw) and its derivative (f w') from immiscible displacement data in core plugs is presented. Linear equations are developed to describe the displacement processes occurring before and ...

This article presents a system of computer aided costs of weld operations by welding for mechanical assemblages. We propose a system based on the combination of two cost estimation methods: on one hand we use the analytic method to formulate the time for weld and for gas and filling metal consumption according to the different parameters of preparing and welding features. The estimating is based upon an evaluation of the filling metal mass used in the welding process. On the other hand, we use the parametric method for the structuring of costs generated by the different features costs which compose the welding process: preparing, pointing and welding. In this case, the estimating is based on the structure of inductors suitable for the scale of each feature. The system we have developed has been implemented with Microsoft Access which permits us to rapidly and efficiently define important and strong data base. The latter constitutes in majority a library of expertise for the enterprise such as the used processes, the preparations, the metals, etc. At last, and to show the developed methods interest and the efficiency of the model, we have treated an industrial project proposed by a collaborating enterprise. The results obtained compared to real time made by welding staff prove the rapidity and the accuracy of the model we have developed.

Aqueous solution properties of polyethylene oxide–block-polypropylene oxide–block-polyethylene oxide TBP [(PEO)103(PPO)39(PEO)103] were studied in the presence of sodium salts with different anions (NaI, NaBr, NaCl, NaF, Na2SO4, Na3PO4) to investigate unimer-to-micelle transition [critical micelle concentration (CMC), critical micellization temperature (CMT)], micelle size and the phase separation (cloud point). This TBP, due to its very hydrophilic (80% PEO) nature does not form micelles at ambient temperatures. Micellization can be induced much below its CMT in water on addition of sodium salts having different anions. Analytical methods viz. fluorescence, FTIR and dynamic light scattering (DLS) were used to monitor the salt-induced micellization. The hydration of respective anion and resultant contribution to its salting-out effect was found to be the governing factor in promoting micellization. The presence of salt decreases the CMC, CMT and phase separation temperature. The salts affect the aggregation process in agreement with an order mentioned in Hofmeister series.

The application of science and engineering to the analysis of priceless paintings and statues dates back several centuries. However, only over the past few decades have analytical methods developed in the physical sciences been able to glean information, from the past and contribute to the analysis, conservation, and dissemination of works of art. By specifically focusing on the visual arts (e.g., on the binomial image processing and paintings), it is the purpose of this column to: 1) sketch the main applications that could benefit from the introduction of ad hoc image processing tools, 2) outline the state-of-the-art, 3) describe the main peculiarities of this field, and 4) discuss the main obstacles impeding a more fruitful cooperation between the image processing community and art historians, restorers, and artists in general.

Acrylamide is a potential cause of a wide spectrum of toxic effects and is classified as probably “carcinogenic in humans”. The discovery of acrylamide in human foods has given rise to extensive studies exploring its formation mechanisms and levels of exposure and has spurred search into suitable analytical procedures for its determination in foodstuffs. However, the exact chemical mechanisms governing

To investigate the composition of dissolved organic matter (DOM) as a function of apparent molecular weight (MW) by rapid analytical methods, high performance liquid chromatography (HPLC)-size exclusion chromatography (SEC) was conducted with sequential on-line detectors ...

Enzyme-linked immunosorbent assays (ELISAs) are the most extensively studied types of immunoassay and their application in pesticide residue monitoring is an area with enormous potential for growth. In comparison with classical analytical methods, ELISA methods offer the possibility of highly sensitive, relatively rapid, and cost-effective measurements. This review introduces the general ELISA formats used, focusing on their use in pesticide analysis. Identifying and studying the effects of interferences in immunoassays is an active area of research and we discuss the matrix effects observed in several studies involving e.g. food, crop and environmental samples. The procedures to eliminate the matrix interferences are briefly discussed.