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[EN] This paper concerns the analysis of random second order linear differential equations. Usually, solving these equations consists of computing the first statistics of the response process, and that task has been an essential goal in the literature. A more ambitious objective is the computation of the solution probability density function. We present advances on these two aspects in the case of general random non-autonomous second order linear differential equations with analytic data processes. The Frobenius method is employed to obtain the stochastic solution in the form of a mean square convergent power series. We demonstrate that the convergence requires the boundedness of the random input coefficients. Further, the mean square error of the Frobenius method is proved to decrease exponentially with the number of terms in the series, although not uniformly in time. Regarding the probability density function of the solution at a given time, which is the focus of the paper, we rely on the law of total probability to express it in closed-form as an expectation. For the computation of this expectation, a sequence of approximating density functions is constructed by reducing the dimensionality of the problem using the truncated power series of the fundamental set. We prove several theoretical results regarding the pointwise convergence of the sequence of density functions and the convergence in total variation. The pointwise convergence turns out to be exponential under a Lipschitz hypothesis. As the density functions are expressed in terms of expectations, we propose a crude Monte Carlo sampling algorithm for their estimation. This algorithm is implemented and applied on several numerical examples designed to illustrate the theoretical findings of the paper. After that, the efficiency of the algorithm is improved by employing the control variates method. Numerical examples corroborate the variance reduction of the Monte Carlo approach. (C) 2020 Elsevier B.V. All ri

[EN] In this paper we extend the study on the linear advection equation with independent stochastic velocity and initial condition performed in Dorini and Cunha (2011). By using both existing and novel results on the stochastic chain rule, we solve the random linear advection equation in the mean square sense. We provide a new expression for the probability density function of the solution stochastic process, which can be computed as accurately as wanted via Monte Carlo simulations, and which does not require the specific probability distribution of the integral of the velocity. This allows us to solve the non-Gaussian velocity case, which was not treated in the aforementioned contribution. Several numerical results illustrate the computations of the probability density function by using our approach. On the other hand, we derive a theoretical partial differential equation for the probability density function of the solution stochastic process. Finally, a shorter and easier derivation of the joint probability density function of the response process at two spatial points is obtained by applying conditional expectations appropriately. (C) 2019 International Association for Mathematics and Computers in Simulation (IMACS). Published by Elsevier B.V. All rights reserved.

[EN] We study the random heat partial differential equation on a bounded domain assuming that the diffusion coefficient and the boundary conditions are random variables, and the initial condition is a stochastic process. Under general conditions, this stochastic system possesses a unique solution stochastic process in the almost sure and mean square senses. To quantify the uncertainty for this solution process, the computation of the probability density function is a major goal. By using a random finite difference scheme, we approximate the stochastic solution at each point by a sequence of random variables, whose probability density functions are computable, i.e., we construct a sequence of approximating density functions. We include numerical experiments to illustrate the applicability of our method.

[EN] In this paper, we deal with the logistic growth model with a time-dependent carrying capacity that was proposed in the literature for the study of the total bacterial biomass during occlusion of healthy human skin. Accounting for data and model errors, randomness is incorporated into the equation by assuming that the input parameters are random variables. The uncertainty is quantified by approximations of the solution stochastic process via truncated series solution together with the random variable transformation method. Numerical examples illustrate the theoretical results.

[EN] A computational approach to approximate the probability density function of random differential equations is based on transformation of random variables and finite difference schemes. The theoretical analysis of this computational method has not been performed in the extant literature. In this paper, we deal with a particular random differential equation: a random diffusion-reaction Poisson-type problem of the form , , with boundary conditions , . Here, alpha, A and B are random variables and is a stochastic process. The term is a stochastic process that solves the random problem in the sample path sense. Via a finite difference scheme, we approximate with a sequence of stochastic processes in both the almost sure and senses. This allows us to find mild conditions under which the probability density function of can be approximated. Illustrative examples are included.

[EN] In this paper we extend the study on the linear advection equation with independent stochastic velocity and initial condition performed in Dorini and Cunha (2011). By using both existing and novel results on the stochastic chain rule, we solve the random linear advection equation in the mean square sense. We provide a new expression for the probability density function of the solution stochastic process, which can be computed as accurately as wanted via Monte Carlo simulations, and which does not require the specific probability distribution of the integral of the velocity. This allows us to solve the non-Gaussian velocity case, which was not treated in the aforementioned contribution. Several numerical results illustrate the computations of the probability density function by using our approach. On the other hand, we derive a theoretical partial differential equation for the probability density function of the solution stochastic process. Finally, a shorter and easier derivation of the joint probability density function of the response process at two spatial points is obtained by applying conditional expectations appropriately. (C) 2019 International Association for Mathematics and Computers in Simulation (IMACS). Published by Elsevier B.V. All rights reserved.

[EN] This paper concerns the analysis of random second order linear differential equations. Usually, solving these equations consists of computing the first statistics of the response process, and that task has been an essential goal in the literature. A more ambitious objective is the computation of the solution probability density function. We present advances on these two aspects in the case of general random non-autonomous second order linear differential equations with analytic data processes. The Frobenius method is employed to obtain the stochastic solution in the form of a mean square convergent power series. We demonstrate that the convergence requires the boundedness of the random input coefficients. Further, the mean square error of the Frobenius method is proved to decrease exponentially with the number of terms in the series, although not uniformly in time. Regarding the probability density function of the solution at a given time, which is the focus of the paper, we rely on the law of total probability to express it in closed-form as an expectation. For the computation of this expectation, a sequence of approximating density functions is constructed by reducing the dimensionality of the problem using the truncated power series of the fundamental set. We prove several theoretical results regarding the pointwise convergence of the sequence of density functions and the convergence in total variation. The pointwise convergence turns out to be exponential under a Lipschitz hypothesis. As the density functions are expressed in terms of expectations, we propose a crude Monte Carlo sampling algorithm for their estimation. This algorithm is implemented and applied on several numerical examples designed to illustrate the theoretical findings of the paper. After that, the efficiency of the algorithm is improved by employing the control variates method. Numerical examples corroborate the variance reduction of the Monte Carlo approach. (C) 2020 Elsevier B.V. All ri

[EN] We study the random heat partial differential equation on a bounded domain assuming that the diffusion coefficient and the boundary conditions are random variables, and the initial condition is a stochastic process. Under general conditions, this stochastic system possesses a unique solution stochastic process in the almost sure and mean square senses. To quantify the uncertainty for this solution process, the computation of the probability density function is a major goal. By using a random finite difference scheme, we approximate the stochastic solution at each point by a sequence of random variables, whose probability density functions are computable, i.e., we construct a sequence of approximating density functions. We include numerical experiments to illustrate the applicability of our method.

[EN] In this paper, we deal with the logistic growth model with a time-dependent carrying capacity that was proposed in the literature for the study of the total bacterial biomass during occlusion of healthy human skin. Accounting for data and model errors, randomness is incorporated into the equation by assuming that the input parameters are random variables. The uncertainty is quantified by approximations of the solution stochastic process via truncated series solution together with the random variable transformation method. Numerical examples illustrate the theoretical results.

More tree species can increase the carbon storage capacity of forests (here referred to as the more species hypothesis) through increased tree productivity and tree abundance resulting from complementarity, but they can also be the consequence of increased tree abundance through increased available energy (more individuals hypothesis). To test these two contrasting hypotheses, we analyse the most plausible pathways in the richness-abundance relationship and its stability along global climatic gradients. We show that positive effect of species richness on tree abundance only prevails in eight of the twenty-three forest regions considered in this study. In the other forest regions, any benefit from having more species is just as likely (9 regions) or even less likely (6 regions) than the effects of having more individuals. We demonstrate that diversity effects prevail in the most productive environments, and abundance effects become dominant towards the most limiting conditions. These findings can contribute to refining cost-effective mitigation strategies based on fostering carbon storage through increased tree diversity. Specifically, in less productive environments, mitigation measures should promote abundance of locally adapted and stress tolerant tree species instead of increasing species richness.

[EN] This paper shows a nice connection between Differential Equations and Probability through an illustrative example. We apply a successfull algebraic strategy together with properties of expectation operator to determine the main statistical properties (mean, variance and covariance) of the solution to a non-autonomous linear differential equation whose initial condition is a random variable. Theoretical findings are illustrated by means of one example.

[EN] This paper shows a nice connection between Differential Equations and Probability through an illustrative example. We apply a successfull algebraic strategy together with properties of expectation operator to determine the main statistical properties (mean, variance and covariance) of the solution to a non-autonomous linear differential equation whose initial condition is a random variable. Theoretical findings are illustrated by means of one example.

Aim In several ecosystems, the diversity of functional species traits has been shown to have a stronger effect on ecosystem functioning than taxonomic diversity alone. However, few studies have explored this idea at a large geographical scale. In a multisite experiment, we unravelled the relationship between ecosystem function and functional completeness of species assemblages using dung beetles as a model group, focusing on dung removal and secondary seed dispersal. Location Seventeen grassland locations across the Western Palaearctic. Methods We used a randomized block design with different exclosure types to control the dung and seed removing activities of individual functional groups of the local dung beetle assemblage. We classified dung beetle species according to resource specialization and into functional groups based on dung processing behaviour (dwellers, tunnellers, rollers) and body size (small, large). Additionally, we assessed the role of other soil macro‐invertebrates. By sampling the dung beetle community and measuring the remaining dung and seeds after the experiment, the impact of each functional group was estimated. Results Dung beetle assemblages differed along a north–south and east–west gradient. Dwellers dominated northernmost sites, whereas at lower latitudes we observed more tunnellers and rollers indicating a functional shift. Resource specialists were more abundant in southern and eastern areas. Overall, functional group diversity enhanced dung removal. More dung (+46.9%) and seeds (+32.1%) were removed in the southern sites and tunnellers and rollers were more effective. At the northernmost sites, where tunnellers were scarce or absent, other soil macro‐invertebrates removed the majority of dung. Main conclusions The conservation of functionally complete dung beetle assemblages is crucial to maintain the ecosystem functions provided by dung beetles. Given the latitudinal variation in functional group diversity, it is reasonable to expect

Purpose: The aim of this publication is to compile available literature data and expert experience regarding skin brachytherapy (BT) in order to produce general recommendations on behalf of the GEC-ESTRO Group. Methods: We have done an exhaustive review of published articles to look for general recommendations. Results: Randomized controlled trials, systemic reviews and meta-analysis are lacking in literature and there is wide variety of prescription techniques successfully used across the radiotherapy centers. BT can be delivered as superficial application (also called contact BT or plesiotherapy) or as interstitial for tumours thicker than 5 mm within any surface, including very irregular. In selected cases, particularly in tumours located within curved surfaces, BT can be advantageous modality from dosimetric and planning point of view when compared to external beam radiotherapy. The general rule in skin BT is that the smaller the target volume, the highest dose per fraction and the shortest overall length of treatment can be used. Conclusion: Skin cancer incidence is rising worldwide. BT offers an effective non-invasive or minimally invasive and relative short treatment that particularly appeals to elder and frail population.

In this paper, we deal with uncertainty quantification for the random Legendre differential equation, with input coefficient $A$ and initial conditions $X_0$ and $X_1$. In a previous study [Calbo G. et al, Comput. Math. Appl., 61(9), 2782--2792 (2011)], a mean square convergent power series solution on $(-1/e,1/e)$ was constructed, under the assumptions of mean fourth integrability of $X_0$ and $X_1$, independence, and at most exponential growth of the absolute moments of $A$. In this paper, we relax these conditions to construct an $\mathrm{L}^p$ solution ($1\leq p\leq\infty$) to the random Legendre differential equation on the whole domain $(-1,1)$, as in its deterministic counterpart. Our hypotheses assume no independence and less integrability of $X_0$ and $X_1$. Moreover, the growth condition on the moments of $A$ is characterized by the boundedness of $A$, which simplifies the proofs significantly. We also provide approximations of the expectation and variance of the response process. The numerical experiments show the wide applicability of our findings. A comparison with Monte Carlo simulations and gPC expansions is performed., Comment: 13 pages; 6 tables

Angiosperms, http://name.umdl.umich.edu/IC-HERB00IC-X-1532580%5DMICH-V-1532580, https://quod.lib.umich.edu/cgi/i/image/api/thumb/herb00ic/1532580/MICH-V-1532580/!250,250, The University of Michigan Library provides access to these materials for educational and research purposes. Some materials may be protected by copyright. If you decide to use any of these materials, you are responsible for making your own legal assessment and securing any necessary permission. If you have questions about the collection, please contact the Herbarium professional staff: herb-dlps-help@umich.edu. If you have concerns about the inclusion of an item in this collection, please contact Library Information Technology: libraryit-info@umich.edu., https://www.lib.umich.edu/about-us/policies/copyright-policy

Angiosperms, http://name.umdl.umich.edu/IC-HERB00IC-X-1518787%5DMICH-V-1518787, https://quod.lib.umich.edu/cgi/i/image/api/thumb/herb00ic/1518787/MICH-V-1518787/!250,250, The University of Michigan Library provides access to these materials for educational and research purposes. Some materials may be protected by copyright. If you decide to use any of these materials, you are responsible for making your own legal assessment and securing any necessary permission. If you have questions about the collection, please contact the Herbarium professional staff: herb-dlps-help@umich.edu. If you have concerns about the inclusion of an item in this collection, please contact Library Information Technology: libraryit-info@umich.edu., https://www.lib.umich.edu/about-us/policies/copyright-policy

An analytical imaging approach to the quantitation of dissolved chemical species absorbed in the visible spectral region is reported. The approach uses digital images of a series of standard solutions of the target substance and their processing with appropriate software to assign a numeric value to each standard in terms of color intensity. Such a value is directly proportional to the analyte concentration and allows the construction of a calibration graph. The results thus obtained are compared with those provided by the classical spectrophotometricmethod used to run calibration curves for colored substances. The chemical imaging technique is relative simple and affordable; in fact, it can be implemented with a commercially available digital camera and the highly user-friendly public domain software ImageJ, developed by the National Institutes of Health and freely available for download on the Internet. The proposed approach can in theory be used to adapt any classic colorimetric method. In a world dominated by increasingly sophisticated equipment, this analytical procedure relies on straightforward, "solidary" analytical chemical principles; in fact, it can facilitate quantitative determinations wherever the purchase and maintenance of spectrophotometersis unaffordable. © Taylor & Francis Group, LLC.

An analytical imaging approach to the quantitation of dissolved chemical species absorbed in the visible spectral region is reported. The approach uses digital images of a series of standard solutions of the target substance and their processing with appropriate software to assign a numeric value to each standard in terms of color intensity. Such a value is directly proportional to the analyte concentration and allows the construction of a calibration graph. The results thus obtained are compared with those provided by the classical spectrophotometricmethod used to run calibration curves for colored substances. The chemical imaging technique is relative simple and affordable; in fact, it can be implemented with a commercially available digital camera and the highly user-friendly public domain software ImageJ, developed by the National Institutes of Health and freely available for download on the Internet. The proposed approach can in theory be used to adapt any classic colorimetric method. In a world dominated by increasingly sophisticated equipment, this analytical procedure relies on straightforward, "solidary" analytical chemical principles; in fact, it can facilitate quantitative determinations wherever the purchase and maintenance of spectrophotometersis unaffordable. © Taylor & Francis Group, LLC.

A quantitative analytical imaging approach for determining the nickel content of metallic meteorites is proposed. The approach uses a digital image of a series of standard solutions of the nickel-dimethylglyoxime coloured chelate and a meteorite sample solution subjected to the same treatment as the nickel standards for quantitation. The image is processed with suitable software to assign a colour-dependent numerical value (analytical signal) to each standard. Such a value is directly proportional to the analyte concentration, which facilitates construction of a calibration graph where the value for the unknown sample can be interpolated to calculate the nickel content of the meteorite. The results thus obtained were validated by comparison with the official, ISO-endorsed spectrophotometric method for nickel. The proposed method is fairly simple and inexpensive; in fact, it uses a commercially available digital camera as measuring instrument and the images it provides are processed with highly user-friendly public domain software (specifically, ImageJ, developed by the National Institutes of Health and freely available for download on the Internet). In a scenario dominated by increasingly sophisticated and expensive equipment, the proposed method provides a cost-effective alternative based on simple, robust hardware that is affordable and can be readily accessed worldwide. This can be especially advantageous for countries were available resources for analytical equipment investments are scant. The proposed method is essentially an adaptation of classical chemical analysis to current, straightforward, robust, cost-effective instrumentation. © 2010 Elsevier B.V. All rights reserved.

The present paper is a critical review dealing with the characteristics, reaction mechanisms and photoproducts, instrumentation and analytical applications of the photo-induced either chemiluminescence or fluorescence. Special attention is paid to the determination of pesticides by continuous-flow methodologies. The paper is divided into several sections covering the most relevant published papers.

Purpose: According to the GYN GEC-ESTRO Recommendations, MRI is needed with the modality of T2 weighted. CT-MR compatible tandem Plus colpostats (T/C) (Nucletron) is widely used in cervical brachytherapy. The major challenge of MRI is the lack of dummy catheters. Therefore, an additional imaging modality is usually required. One disadvantage of sliced-based reconstruction is that resolution in longitudinal directions can be affected by the slice thickness. The aim of this study is to present a modified T/C applicator in which the catheter visibility is significantly improved. Methods and materials: A modification to the existing T/C applicator has been made available, increasing the catheter entrance diameter. It allows a greater dummy catheter diameter, and consequently it can be filled with more material per unit length. Visibility was studied with different materials. Results: The catheter filled with saline water plus iodine Compound was clearly seen in both axial and longitudinal acquisitions, To avoid uncertainties introduced by the slice thickness, a simple procedure is presented using longitudinal acquisitions. Conclusions: The modified applicator plus catheter allows a powerful signal in T2 weighted MRI, using a very simple and accessible material. Also, a method is proposed to solve the problem of the uncertainty derived from slice thickness using few longitudinal acquisitions

The purpose of this study is to obtain the dosimetric parameters of a new Co-60 source used in high dose rate brachytherapy and manufactured by BEBIG (Eckert & Ziegler BEBIG GmbH, Germany). The Monte Carlo method has been used to obtain the dose rate distribution in the updated TG-43UI formalism of the American Association of Physicists in Medicine. In addition, to aid the quality control process on treatment planning systems (TPS), a two-dimensional rectangular dose rate table, coherent with the TG-43UI dose calculation formalism, is given. These dosimetric data sets can be used as input data of the TPS calculations and to validate them.

[EN] This paper presents the analytical determination of the pesticide Asulam based on its native fluorescence. The method was optimized in either a flow injection analysis (FIA) assembly or in batch. The maximum fluorescence intensity was observed for basic pH solutions and at a lambda(ex) of 258 nm and lambda(em) of 342 nm. The influence of different empirical parameters, such as the pH, the presence of surfactants, solvent polarity or solved oxygen amount, was studied. The calibration range was fitted with a linear equation from 0.01-3 mg l(-1) Asulam and 0.005-15 mg l(-1) Asulam for batch and continuous-flow, respectively. The RSD for both procedures was 1.0%. After testing the influence of a large series of potential interferents, the method was applied to water samples from different locations.

[EN] This paper presents the analytical determination of the pesticide Asulam based on its native fluorescence. The method was optimized in either a flow injection analysis (FIA) assembly or in batch. The maximum fluorescence intensity was observed for basic pH solutions and at a lambda(ex) of 258 nm and lambda(em) of 342 nm. The influence of different empirical parameters, such as the pH, the presence of surfactants, solvent polarity or solved oxygen amount, was studied. The calibration range was fitted with a linear equation from 0.01-3 mg l(-1) Asulam and 0.005-15 mg l(-1) Asulam for batch and continuous-flow, respectively. The RSD for both procedures was 1.0%. After testing the influence of a large series of potential interferents, the method was applied to water samples from different locations.

[EN] A new, robust and simple method is proposed for the chemiluminescent determination of the pesticide Bromoxynil. The empirical procedure is performed with the aid of a flow-injection manifold provided with an on-line photo-reactor to obtain chemiluminescent photofragments. After a period of 12 s of irradiation with an 8 W low-pressure mercury lamp, a chemiluminescent oxidation was performed with the system potassium permanganate in a polyphosphoric acid medium. The photolysis required a basic medium (KOH 0.014 mol l(-1)) with ethanol (1%) as a sensitizer. The method allowed the determination of 134 samples h(-1) of Bromoxynil in a wide interval of concentrations, over the range 5 x 10(-3) - 1 mg l(-1); the detection limit was 5 x 10(-3) mg l(-1). The RSD (n = 24) at 0.25 mg l(-1) of the pesticide level was 2.3%. The method was applied to a water sample and to a formulation.

The present paper is dealing with an analytical strategy based on coupling photodegradation, chemiluminescence and multicommutation continuous-flow methodology for the determination of the pesticide Propanil, a common herbicide. The pesticide solution is inserted as small segments sequentially alternated with segments of the solution for adjusting the suitable medium for the photodegradation. Both flow-rates (sample and medium) are adjusted to required time for photodegradation, 2.0 min; and then, the resulting solution is also sequentially inserted as segments alternated with segments of the oxidizing solutions system, 1.00 x 10(-4) mol 1(-1) potassium permanganate in 2.00 mol 1(-1) sulphuric acid medium. The calibration range, from 10 mu g 1(-1) to 25 mg 1(-1), resulted in a linear behaviour over the range 10 mu g 1(-1)-5 mg 1(-1) and fitting the linear equation: I = 780.30C + 95.28; correlation coefficient 0.9999. The limit of detection was 8 mu g 1(-1) and the sample throughput 20 h(-1). After testing the influence of a large series of potential interferents the method is applied to water samples obtained from different places and to one formulation. The method is valid for the determination of other pesticides from the same chemical family, namely: alachlor, flumetsulam, furalaxyl and ofurace. Calibration graphs, limits of detection, repeatability and determination in water samples are obtained for each reported pesticide. (c) 2005 Elsevier B.V. All rights reserved.

We present a critical presentation and discussion on molecular connectivity applied to analytical fields, giving special attention to predicting the chemiluminescent behavior of pharmaceuticals and pesticides. Molecular connectivity has been largely applied to predict the therapeutic effects of pharmaceuticals and rarely to predictions in analytical chemistry-basically to chromatographic processes and recently to liquid-phase chemiluminescence. (c) 2005 Elsevier Ltd. All rights reserved.

[EN] A flow injection analysis (FIA) manifold for the determination of penicillamine in pharmaceutical preparations is proposed. The manifold includes a solid-phase reactor for the in situ production of the derivatizing reagent, Co(II) ion, which forms a coloured complex with penicillamine in an alkaline medium. The reactor is prepared by natural immobilization of cobalt carbonate on a polymer matrix, which endows it with a high mechanical and microbiological stability. The cobalt released by passage of a 5 x 10(-4) Mol l(-1) sulphuric acid stream at a flow-rate of 2.3 ml min(-1) is merged with a volume of 314 mu l of sample containing penicillamine in ammonium-ammonia buffer at pH 9.5 to measure the absorbance at 360 nm. Beer's law is obeyed over the penicillamine concentration range 5-60 mg l(-1). The limit of detection (LOD) of the method is 1 mg l(-1) and its throughput 70 samples h(-1). (c) 2005 Elsevier B.V. All rights reserved.

[EN] A flow injection analysis (FIA) manifold for the determination of penicillamine in pharmaceutical preparations is proposed. The manifold includes a solid-phase reactor for the in situ production of the derivatizing reagent, Co(II) ion, which forms a coloured complex with penicillamine in an alkaline medium. The reactor is prepared by natural immobilization of cobalt carbonate on a polymer matrix, which endows it with a high mechanical and microbiological stability. The cobalt released by passage of a 5 x 10(-4) Mol l(-1) sulphuric acid stream at a flow-rate of 2.3 ml min(-1) is merged with a volume of 314 mu l of sample containing penicillamine in ammonium-ammonia buffer at pH 9.5 to measure the absorbance at 360 nm. Beer's law is obeyed over the penicillamine concentration range 5-60 mg l(-1). The limit of detection (LOD) of the method is 1 mg l(-1) and its throughput 70 samples h(-1). (c) 2005 Elsevier B.V. All rights reserved.

We present a critical presentation and discussion on molecular connectivity applied to analytical fields, giving special attention to predicting the chemiluminescent behavior of pharmaceuticals and pesticides. Molecular connectivity has been largely applied to predict the therapeutic effects of pharmaceuticals and rarely to predictions in analytical chemistry-basically to chromatographic processes and recently to liquid-phase chemiluminescence. (c) 2005 Elsevier Ltd. All rights reserved.

This paper deals with a straightforward automated method for the determination of asulam in water based on the use of a flow manifold including three computer-controlled solenoid valves. The method involves irradiating on an aqueous solution of asulam in glycine buffer at pH 8.3 with UV light during 90 s, then follows the oxidation with potassium permanganate in a sulphuric medium and chemiluminescence-based detection of the resulting photoproducts. The limit of detection thus achieved is 40 mug l(-1). The detector response is linear up to a 5 mg l(-1) asulam concentration and the throughput is 30 samples h(-1). In parallel tests, oxidation with alkaline ferricyanide was also assessed and the results compared (sensitivity, selectivity and reproducibility) with those from oxidation with potassium permanganate in acidic medium. The use of a flow based on solenoid valves results in substantial reagent savings and constitutes a further extension of clean chemistry procedures. To the authors' knowledge, this is the first chemiluminescence-based determination of asulam and also the first based on multicommutation analysis. (C) 2004 Elsevier B.V. All rights reserved.

The present manuscript deals with a simple and sensitive flow-injection method for the chemiluminescent determination of thiazides. The method is based on the on-line photodegradation and chemiluminescent determination of the resulting photo-fragments. The on-line photodegradation is performed in basic medium by using a photoreactor consisting of a 550 cm long x 0.8 mm ID piece of PTFE tubing helically coiled around an 8 W low-pressure mercury lamp. The determination of the photo-irradiated thiazides is performed by a chemiluminescent oxidative reaction with Ce(IV) in sulphuric acid medium. A heterogeneous group of thiazides (indapamide, metolazone, hydroflumethiazide, chlorthalidone and bendroflumethiazide) has been studied. Hydrochlorothiazide was selected as a test substance. The "on-line" photochemical reaction approach allows the sensitive chemiluminescent determination of thiazides which do not present native chemiluminescence in the absence of sensitizers such as Rhodamine 6G. Linear calibration graphs were typically over the range 0.5-12 mug ml(-1) (indapamide, metolazone, hydroflumethiazide and chlorthalidone); and over the range 0.5-5 mug ml(-1) (hydrochlorothiazide). Limits of detection ranged between 0.005 mug ml(-1) (hydrochlorothiazide) and 0.06 mug ml(-1) (bendroflumethiazide). The relative standard deviation for the test substance was 2.0% for 2 mug l(-1) of the drug (n = 11) and the throughput was 65 h(-1) in all cases. The assessment of the photodegradation step on the molecular structure of thiazides was established by recording UV and fluorimetric spectra. The viability of the on-line photoinduced fluorescent determination of hydroflumethiazide and bendroflumethiazide was confirmed. The method was also applied to the determination of hydrochlorothiazide in commercially available formulation. (C) 2004 Elsevier B.V. All rights reserved.

The present manuscript is dealing with the application of molecular connectivity calculations to predict the chemiluminescent behaviour of ergot alkaloids when they react with common strong oxidants in liquid phase. Twenty compounds were theoretically studied by means of a discriminant equation formerly published, being 19 of them predicted as chemiluminescent with a high probability. Empirical confirmation of the chemiluminometric behaviour is performed with the few soluble and commercially available ergot alkaloids. On the basis of these results, a new FIA-direct chemiluminescent method is proposed for the determination of the ergot presenting the higher light emission, the pharmaceutical ergotamine. The method is based on the oxidation of the drug by K3[Fe(CN)6] in sodium hydroxide medium, at seventy degrees and enhanced by the presence of dioxane. The studied calibration up to 5.0 mg l−1, revealed a linear dynamic graph up to 0.5 mg l−1. The reproducibility between days resulted in a rsd (in slope %) of 8.9 (n, 5) and the repeatability with a %R.S.D. (n = 20) of 1.9 and 0.6 for 0.3 and 4.0 mg l−1, respectively. LOD (s/n = 3) of 6 × 10−7 mg l−1 and sample throughput of 73 h−1. The influence of foreign compounds is also tested and the optimised flow-assembly is applied to other compounds of the ergot alkaloids family. © 2004 Elsevier B.V. All rights reserved.

The present manuscript deals with a simple and sensitive flow-injection method for the chemiluminescent determination of thiazides. The method is based on the on-line photodegradation and chemiluminescent determination of the resulting photo-fragments. The on-line photodegradation is performed in basic medium by using a photoreactor consisting of a 550 cm long x 0.8 mm ID piece of PTFE tubing helically coiled around an 8 W low-pressure mercury lamp. The determination of the photo-irradiated thiazides is performed by a chemiluminescent oxidative reaction with Ce(IV) in sulphuric acid medium. A heterogeneous group of thiazides (indapamide, metolazone, hydroflumethiazide, chlorthalidone and bendroflumethiazide) has been studied. Hydrochlorothiazide was selected as a test substance. The "on-line" photochemical reaction approach allows the sensitive chemiluminescent determination of thiazides which do not present native chemiluminescence in the absence of sensitizers such as Rhodamine 6G. Linear calibration graphs were typically over the range 0.5-12 mug ml(-1) (indapamide, metolazone, hydroflumethiazide and chlorthalidone); and over the range 0.5-5 mug ml(-1) (hydrochlorothiazide). Limits of detection ranged between 0.005 mug ml(-1) (hydrochlorothiazide) and 0.06 mug ml(-1) (bendroflumethiazide). The relative standard deviation for the test substance was 2.0% for 2 mug l(-1) of the drug (n = 11) and the throughput was 65 h(-1) in all cases. The assessment of the photodegradation step on the molecular structure of thiazides was established by recording UV and fluorimetric spectra. The viability of the on-line photoinduced fluorescent determination of hydroflumethiazide and bendroflumethiazide was confirmed. The method was also applied to the determination of hydrochlorothiazide in commercially available formulation. (C) 2004 Elsevier B.V. All rights reserved.

This paper deals with a straightforward automated method for the determination of asulam in water based on the use of a flow manifold including three computer-controlled solenoid valves. The method involves irradiating on an aqueous solution of asulam in glycine buffer at pH 8.3 with UV light during 90 s, then follows the oxidation with potassium permanganate in a sulphuric medium and chemiluminescence-based detection of the resulting photoproducts. The limit of detection thus achieved is 40 mug l(-1). The detector response is linear up to a 5 mg l(-1) asulam concentration and the throughput is 30 samples h(-1). In parallel tests, oxidation with alkaline ferricyanide was also assessed and the results compared (sensitivity, selectivity and reproducibility) with those from oxidation with potassium permanganate in acidic medium. The use of a flow based on solenoid valves results in substantial reagent savings and constitutes a further extension of clean chemistry procedures. To the authors' knowledge, this is the first chemiluminescence-based determination of asulam and also the first based on multicommutation analysis. (C) 2004 Elsevier B.V. All rights reserved.

[EN] A sensitive and fully automated method for determination of aldicarb in technical formulations (Temik) and mineral waters is proposed. The automation of the flow-assembly is based on the multicommutation approach, which uses a set of solenoid valves acting as independent switchers. The operating cycle for obtaining a typical analytical transient signal can be easily programmed by means of a home-made software running in the Windows environment. The manifold is provided with a photoreactor consisting of a 150 cm long x 0.8 mm i.d. piece of PTFE tubing coiled around a 20 W low-pressure mercury lamp. The determination of aldicarb is performed on the basis of the iron(III) catalytic mineralization of the pesticide by UV irradiation (150 s), and the chemiluminescent (CL) behavior of the photodegradated pesticide in presence of potassium permanganate and quinine sulphate as sensitizer. UV irradiation of aldicarb turns the very week chemiluminescent pesticide into a strongly chemiluminescent photoproduct. The method is linear over the range 2.2-100.0 mug l(-1) of aldicarb; the limit of detection is 0.069 mug l(-1); the reproducibility (as the R.S.D. of 20 peaks of a 24 mug l (1) solution) is 3.7% and the sample throughput is 17 h (C) 2004 Elsevier B.V. All rights reserved.

This article deals with the simultaneous determination of three dissolution profiles with the aid of the new and emerging continuous-flow methodology known as multicommutation. This methodology is based on a flow network of a set of solenoid valves controlled by the computer and acting as independent multicommutators to allow the easy and automated control of flowing solutions. The obtained three dissolution profiles from one dosage form are the whole formulation profile or "global profile" recommended by pharmacopoeias, and, at same time, are recorded two "individual" profiles from two drugs present in the formulation. This is the second attempt to obtain simultaneously three dissolution profiles with a single spectrophotometric detector and the first with the multicommutation methodology. The selected pharmaceutical formulations contained a couple of active principles with overlapped spectra, namely sulphamethoxazole and trimethoprim or hydrochlorothiazide and captopril. The obtained empirical plots profiles fitted with the Higuchi equation also known as the three-parameter equation. (C) 2004 Elsevier B.V. All rights reserved.

A direct chemiluminescent procedure for determination of hydroquinone based on the emergent flow methodology known as multicommutation or tandem-flow is presented for first time. The manifold was based on a set of three channels and three solenoid valves; and, the determination was performed at 60degreesC and at flow-rate of 7.5 ml min(-1). The complete cycle lasted 35 s, which resulted in a sample flow trough of 103 h(-1). The chemical process was the hydroquinone oxidation with the system sulphuric acid-potassium permanganate; and the light emission was clearly enhanced by the presence of quinine sulphate and benzalkonium chloride reaching a detection limit of 30 Rg l(-1). The dynamic interval was over the range 0.1-15.0 mgl(-1) and a large list of interferents were assayed; the chemical robustness was also tested. The method was applied to different type of samples: namely, pharmaceutical formulations, a photographic solution and irrigation and residual superficial waters. (C) 2004 Elsevier B.V. All rights reserved.

[EN] A sensitive and fully automated method for determination of aldicarb in technical formulations (Temik) and mineral waters is proposed. The automation of the flow-assembly is based on the multicommutation approach, which uses a set of solenoid valves acting as independent switchers. The operating cycle for obtaining a typical analytical transient signal can be easily programmed by means of a home-made software running in the Windows environment. The manifold is provided with a photoreactor consisting of a 150 cm long x 0.8 mm i.d. piece of PTFE tubing coiled around a 20 W low-pressure mercury lamp. The determination of aldicarb is performed on the basis of the iron(III) catalytic mineralization of the pesticide by UV irradiation (150 s), and the chemiluminescent (CL) behavior of the photodegradated pesticide in presence of potassium permanganate and quinine sulphate as sensitizer. UV irradiation of aldicarb turns the very week chemiluminescent pesticide into a strongly chemiluminescent photoproduct. The method is linear over the range 2.2-100.0 mug l(-1) of aldicarb; the limit of detection is 0.069 mug l(-1); the reproducibility (as the R.S.D. of 20 peaks of a 24 mug l (1) solution) is 3.7% and the sample throughput is 17 h (C) 2004 Elsevier B.V. All rights reserved.

The present manuscript is dealing with the application of molecular connectivity calculations to predict the chemiluminescent behaviour of ergot alkaloids when they react with common strong oxidants in liquid phase. Twenty compounds were theoretically studied by means of a discriminant equation formerly published, being 19 of them predicted as chemiluminescent with a high probability. Empirical confirmation of the chemiluminometric behaviour is performed with the few soluble and commercially available ergot alkaloids. On the basis of these results, a new FIA-direct chemiluminescent method is proposed for the determination of the ergot presenting the higher light emission, the pharmaceutical ergotamine. The method is based on the oxidation of the drug by K3[Fe(CN)6] in sodium hydroxide medium, at seventy degrees and enhanced by the presence of dioxane. The studied calibration up to 5.0 mg l−1, revealed a linear dynamic graph up to 0.5 mg l−1. The reproducibility between days resulted in a rsd (in slope %) of 8.9 (n, 5) and the repeatability with a %R.S.D. (n = 20) of 1.9 and 0.6 for 0.3 and 4.0 mg l−1, respectively. LOD (s/n = 3) of 6 × 10−7 mg l−1 and sample throughput of 73 h−1. The influence of foreign compounds is also tested and the optimised flow-assembly is applied to other compounds of the ergot alkaloids family. © 2004 Elsevier B.V. All rights reserved.

This article deals with the simultaneous determination of three dissolution profiles with the aid of the new and emerging continuous-flow methodology known as multicommutation. This methodology is based on a flow network of a set of solenoid valves controlled by the computer and acting as independent multicommutators to allow the easy and automated control of flowing solutions. The obtained three dissolution profiles from one dosage form are the whole formulation profile or "global profile" recommended by pharmacopoeias, and, at same time, are recorded two "individual" profiles from two drugs present in the formulation. This is the second attempt to obtain simultaneously three dissolution profiles with a single spectrophotometric detector and the first with the multicommutation methodology. The selected pharmaceutical formulations contained a couple of active principles with overlapped spectra, namely sulphamethoxazole and trimethoprim or hydrochlorothiazide and captopril. The obtained empirical plots profiles fitted with the Higuchi equation also known as the three-parameter equation. (C) 2004 Elsevier B.V. All rights reserved.

A direct chemiluminescent procedure for determination of hydroquinone based on the emergent flow methodology known as multicommutation or tandem-flow is presented for first time. The manifold was based on a set of three channels and three solenoid valves; and, the determination was performed at 60degreesC and at flow-rate of 7.5 ml min(-1). The complete cycle lasted 35 s, which resulted in a sample flow trough of 103 h(-1). The chemical process was the hydroquinone oxidation with the system sulphuric acid-potassium permanganate; and the light emission was clearly enhanced by the presence of quinine sulphate and benzalkonium chloride reaching a detection limit of 30 Rg l(-1). The dynamic interval was over the range 0.1-15.0 mgl(-1) and a large list of interferents were assayed; the chemical robustness was also tested. The method was applied to different type of samples: namely, pharmaceutical formulations, a photographic solution and irrigation and residual superficial waters. (C) 2004 Elsevier B.V. All rights reserved.

[EN] A flow injection assembly for the determination of chloramine-T is proposed. The sample (213 mu l) is inserted into the carrier, de-ionized water flowing at 4.1 mi min(-1). This carrier merges with a mixture of potassium iodide and sulphuric acid, and the resulting solution flows to the flow cell through a reactor 66 cm long. The chloramine-T oxidises the iodide to tri-iodide. The resulting iodide/iodine ratio is biamperometrically tested. The calibration graph is linear up to 65 mu g ml(-1) chloramine-T; the limit of detection is 0.5 mu g ml(-1); the relative standard deviation (r.s.d) of the calibration slope is 2.8% for a series of eight independent calibrations. The r.s.d. of a series of 74 peaks for 40 mu g ml(-1) chloramine-T) is 0.8%, and the sample throughput 220 h(-1). Few foreign substances interfered. The method is applied to pharmaceutical, veterinary and waste water samples.