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This report presents a novel methodology based in the quickly acquisition of full UV-vis range spectra combined with the joint determination of kinetic parameters and chemiluminescence signals. Then this technique allows obtaining three-dimensional chemiluminescence spectra profiles containing kinetic and spectroscopic information. That is especially useful for resolving mixtures of luminophors because of more analytical information for each analyte is available increasing the selectivity relative to conventional chemiluminescence methods. To accomplish this, a conventional Back-Thinned CCD detector is used and the three-dimensional chemiluminescence spectra is subsequently processed so that two-dimensional spectra with different trajectories can be obtained by dedicated software CLTotal. The potential of the proposed analytical methodology was assessed for the simultaneous determination of two polycyclic aromatic hydrocarbons. The chemiluminescent reaction between DNPO and hydrogen peroxide induced by their presence was used to record 3D spectra and the software CLTotal to subsequently construct linear variable-angle trajectories in the spectra, in order to obtain more selective 2D spectra facilitating the simultaneous determination of the analytes. The results of the statistical analysis testify to the usefulness of the proposed method for the intended purpose., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

This work proposes a new method for the in vitro evaluation of the effect of UV irradiation on the production of free radicals and other reactive species during the photodecomposition of drugs. The method was based on the UV irradiation of antibiotics molecules to generate excited states that undergo to homolytic bond cleavages. These reactive species can be detected by their ability to oxidize the luminol, producing the electronically excited aminophtalate, which decays to the ground state releasing electromagnetic radiation in the visible zone of the spectrum. This method was applied to penicillin G, nafcillin, azlocillin and neomycin dissolved in water. It was found that the intensity of the luminol chemiluminescence emission (CL) was proportional to the concentration and dependent on the molecular structure of these drugs. Under the optimized conditions, it was found that penicillin and azlocillin were the most susceptible to photodegradation, while neomycin sulfate was the less affected by the UV light. It was observed that the addition to the antibiotics dissolutions of a hydro-alcoholic extract of petals of calyxes of Roselle reduced the CL intensity, indicating that the extract was able to scavenge the free radicals in the irradiated drugs. This result suggest that its addition to the antibiotics can help in the protection against the radicals formed during the exposition to solar light of patients treated with topic similar antibiotics., (Copyright © 2018. Published by Elsevier B.V.)

High-performance liquid chromatography (HPLC) was used to separate oxamyl from other pesticides in drinking water and tomato paste. The eluate emerging from the column tail was mixed with an alkaline solution of Co 2+ in EDTA and irradiated with UV light to induce photolysis of the carbamate in order to obtain free radicals and other reactive species that oxidize luminol and produce chemiluminescence (CL) as a result. The intensity of the CL signal was monitored in the form of chromatographic peaks. Under the optimum operating conditions for the HPLC-UV-CL system, the analyte concentration was linearly related to peak area. The limit of detection as determined in accordance with the IUPAC criterion was 0.17 mg L -1 . Oxamyl was successfully extracted with recoveries of 88.7-103.1% from spiked tomato paste by using a simple QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) sample preparation approach. Similar recoveries were obtained from drinking water samples spiked with oxamyl concentrations above the LOD. The proposed method is a simple, fast, accurate choice for quantifying this pesticide.

A simple, sensitive method for determining gibberellic acid based on photochemically induced fluorescence detection was developed to determine this plant growth regulator in a technical formulation, tomato, and fruit samples. The principle for the determination is the photochemical reactivity of the gibberellic acid, being consistent with the occurrence of photoaromatization and photochemical dimerization with loss of carbon dioxide, and with the likely formation of various fluorescent photoproducts. Six min of UV (mainly at 253.7 nm) irradiation in a solution containing 50% (v/v) methanol and buffer at pH 5 provided the best results. The calibration curve was linear over the concentration range 50-150 ng mL(-1), and the limit of detection was 1.7 ng mL(-1). The method is useful to determine gibberellic acid in samples with background fluorescence such as plum and tomato without the need for labor-intensive preparation as a result of UV irradiation suppressing the fluorescent background.

Introduction: 1-Naphthylacetic and 2-naphthoxyacetic acids belong to the synthetic branch of auxins. Auxins have attracted considerable interest as a subject of study by virtue of their biological and physiological significance. Their broad use as plant growth regulators has raised the need for simple, rapid, sensitive and selective analytical methods for their determination in real samples., Objective: The primary aim of this work was to develop an analytical method for the simultaneous determination of 1-naphthylacetic acid and 2-naphthoxyacetic acid in commercial technical formulations, tomato and various fruit types (apple, strawberry, orange and plum) by room temperature phosphorescence., Methodology: Filtrated solutions of aqueous slurries from ecological fruit and tomato samples are acidified and then extracted with dichloromethane. Once the solvent is evaporated, the dried residue is dissolved in sodium dodecyl sulphate (a micellar agent), and supplied with thallium (I) nitrate as an external heavy atom source and sodium sulphite as deoxygenation agent to enhance the ensuing phosphorescence., Results: The broad-band overlapping spectra for the two analytes were resolved by first- and second-derivative phosphorescence spectrometry. Zero-crossing measurements at 488.5 nm in the first-derivative spectrum and 469.5 nm in the second derivative spectrum exhibited a linear dependence on the 2-naphthoxyacetic acid and 1-naphthylacetic acid concentration, respectively. The detection limits as determined in accordance with the error propagation theory were 11.5 ng/mL for 1-naphthylacetic acid and 15.6 ng/mL for 2-naphthoxyacetic acid., Conclusion: The proposed method affords the determination of 1-naphthylacetic acid and 2-naphthoxyacetic acid in real samples with near-quantitative recoveries from agricultural products., (Copyright © 2011 John Wiley & Sons, Ltd.)

A sensitive chemiluminescence method for vitamin B(12) using a charge-coupled device (CCD) photodetector combined with on-line UV-persulfate oxidation in a simple continuous flow system has been developed. The principle for the determination of vitamin B(12) is based on the enhancive effect of cobalt (II) on the chemiluminescence reaction between luminol and percarbonate in alkaline medium. In addition, percarbonate has been investigated and proposed as a powerful source of hydrogen peroxide as oxidant agent in this chemiluminescence reaction. The digestion of vitamin B(12) to release the cobalt (II) is reached by UV irradiation treatment in a persulfate medium. The CCD detector, directly connected to the flow cell, is used with the continuous flow manifold to obtain the full spectral characteristics of cobalt (II) catalyzed luminol-percarbonate reaction. The vitamin B(12) oxidation process and chemical conditions for the chemiluminescence reaction were investigated and optimized. The increment of the emission intensity was proportional to the concentration of vitamin B(12) , giving a second-order calibration graph over the cobalt (II) concentration range from 10 to 5000 μg L(-1)(r(2) = 0.9985) with a detection limit of 9.3 μg L(-1). The proposed method was applied to the determination of vitamin B(12) in different kinds of pharmaceuticals., (Copyright © 2011 John Wiley & Sons, Ltd.)

It was found that the ions Cu(II), Ni(II) and Zn(II) can attenuate the peroxyoxalate chemiluminescence emission, which was used to develop an analytical procedure for the simultaneous determination of these ions in a stopped-flow system using Partial Least Square (PLS) calibration. Acetonitrile was used to dissolve TCPO and to prepare a mixture of fluorescein, H(2)O(2) and imidazole. These solutions were carried using two peristaltic pumps, while a third pump was employed to propel the aqueous solutions of the metallic ions. All solutions were mixed in the quartz cell of a Campsec CL detector connected to a personal computer to register the CL development using the Clarity software. Under the optimum operative conditions each ion produced a specific CL development with maximum intensities at 0.280 min for Zn(II), 0.307 min for Ni(II) and 0.327 min for Cu(II). The latter exhibited the highest inhibition effect. The experimental calibration set was composed of 16 sample solutions using a central design for three component mixtures with scaled values. The proposed method offers the advantages of simplicity, good precision and accuracy for the simultaneous determination of Ni(2+), Cu(2+) and Zn(2+) in water samples.

Introduction: The cobalt is an essential element for leguminous plants but may be harmful for other species; for that reason determination of Co(II) is very important for the management of polluted areas and for discover plants with capacity for the hyperaccumulation of heavy metals, which has produced a growing necessity of fast, sensitive and selective analytical techniques., Objective: To develop an analytical procedure for the determination of cobalt in plant tissue by coupling the ionic chromatography to the luminol-based chemiluminescence detection., Methodology: The sample was digested in a mixture of concentrated nitric acid and hydrogen peroxide, using an microwave oven to dissolve the Co(II). The solution containing Co(II) ions was injected to an ionic chromatograph using oxalic acid as the eluent. The detection was based on the catalytic effect of Co(II) on the luminol chemiluminescence using perborate or percarbonate as oxidants. Experimental variables, such as concentrations, pH, flow rates and acid digestion conditions were optimised., Results: Well-resolved chromatographic peaks were obtained. The height and area showed linear dependences with the Co(II) concentration, which were used to quantify the heavy metal, with recoveries up to 95%. The microwave irradiation (60  s) was sufficient for the complete mineralisation of 200  mg of sample, employing 2  mL of the acid mixture. The method was free from the interferences, requiring less than 12 minutes to complete the analysis., Conclusion: The method was simple and rapid for the determination of cobalt in plant tissue with detection limits comparable to those obtained with more sophisticated and expensive analytical equipment., (Copyright © 2010 John Wiley & Sons, Ltd.)

The first application of the flow analysis coupled with chemiluminescence detection and based on stopped-flow chemistry to the simultaneous determination of two components, using a two equation system, is described. The proposed method to determine simultaneously morphine and naloxone is based on the chemiluminescence oxidation of these compounds by their reaction with potassium permanganate in an acidic medium. The main feature of the system used is that the recording of the whole chemiluminescence intensity-versus-time profiles can be obtained, using the stopped-flow technique in a continuous-flow system. Then, the chemiluminescent signals obtained at two times of these profiles can be used to determine the concentration of both opiate narcotics. The effect of common emission enhancers on the chemiluminescence emission of these compounds in different acidic media, using the above-mentioned technique, was studied, in order to achieve the best conditions in which, the CL profiles of both compounds should be additive. The parameters selected were sulphuric acid 1.0 mol L(-1), permanganate 0.2 mmolL(-1) and formaldehyde 0.8 mol L(-1). Taken in account the different profiles of the transient CL signal obtained with each compounds, using the selected chemical conditions, two measurement times (1.4 and 4.8s) of these responses curves were considered with the purpose to establish a simple 2 x 2 matrix calculation. Using the chemiluminiscent signals obtained at these times, a linear calibration graph was obtained for each one of the compounds between 0.01 and 1.00 mg L(-1) for morphine and 0.10-1.50 mg L(-1) for naloxone. The present chemiluminescence procedure was applied to the determination of both compounds in mixtures and was found to be satisfactory.

A novel alternative for the simultaneous determination of compounds with similar structure is described, using the whole chemiluminescence-time profiles, acquired by the stopped-flow technique, in combination with mathematical treatments of multivariate calibration. The proposed method is based on the chemiluminescent oxidation of morphine and naloxone by their reaction with potassium permanganate in an acidic medium, using formaldehyde as co-factor. The whole chemiluminescence-time profiles, acquired using the stopped-flow technique in a continuous-flow system, allowed the use of the time-resolved chemiluminescence (CL) data in combination with multivariate calibration techniques, as partial least squares (PLS), for the quantitative determination of both opiate narcotics in binary mixtures. In order to achieve overcoat the additivity of the CL profiles and beside to obtain CL profiles for each drug the most separated as possible in the time, the optimum chemical conditions for the CL emission were investigated. The effect of common emission enhancers on the CL emission obtained in the oxidation reaction of these compounds in different acidic media was studied. The parameters selected were sulphuric acid 1.0 mol L(-1), permanganate 0.2 mmol L(-1) and formaldehyde 0.8 mol L(-1). A calibration set of standard samples was designed by combination of a factorial design, with three levels for each factor and a central composite design. Finally, with the aim of validating the chemometric proposed method, a prediction set of binary samples was prepared. Using the multivariate calibration method proposed, the analytes were determined in synthetic samples, obtaining recoveries of 97-109%.

A novel chemiluminescence method for the determination of antu has been developed based on the reaction between potassium permanganate in acid medium with this rat-poison in the presence of formaldehyde as an emission enhancer. The main feature of the system used is that the recording of the whole chemiluminescence intensity-vs-time profiles can be obtained, using the stopped-flow technique in a continuous-flow system. This enables the use of three quantitative parameters adjustable via software settings, one of them a typically kinetic parameter, such as rate of the light-decay reaction, and the others conventional parameters, such as maximum emission intensity and total emission area, which are proportional to the analyte concentration. The optimum chemical conditions for the chemiluminescence emission were investigated. The effect of common emission enhancers, such as formic acid, formaldehyde, glutaraldehyde, acetaldehyde, quinine, fluorescein, rhodamine B, and rhodamine 6G, was studied. The parameters selected were sulfuric acid 4.0 mol L(-)(1), permanganate 0.1 mmol L(-)(1), and formaldehyde 1.0 mol L(-)(1). The calibration graphs obtained with each one of the measurement parameters were linear for the concentration range from 0.05 to 3.00 microg mL(-)(1). The detection limits ranged from 0.005 to 0.010 microg mL(-)(1), and RSD values (n = 10) of 0.99-1.79% at a 0.30 microg mL(-)(1) concentration level and 1.71-2.22% at a 1.0 microg mL(-)(1) concentration level were obtained. The present chemiluminescence procedures were applied to the determination of antu in different kinds of samples, such as river water, wheat, barley, and oat grain samples. Recovery values not significantly different from the spiked amount were found for these determinations.

The chemiluminescent behaviour of captopril when reacted with a common oxidant, potassium permanganate in different acidic media is described, using the stopped-flow technique in a continuous-flow system. A 22 bit analogue-to-digital converter that acquires analogue signals at -10 and +10V and allows the power supply to the peristaltic pump to be interrupted is used in the time-resolved chemiluminescence manifold to ensure rapid, efficient mixing of chemiluminescent reagent and sample immediately before reaching the detector; this results in high precision and detectability, particularly with fast, short-lived emissions. The optimum chemical conditions for the chemiluminescence emission were investigated. It was found that a weak CL emission was emitted during the oxidation of this drug with potassium permanganate in acidic solution. The effect of common emission enhancers such as formic acid, formaldehyde, glutaraldehyde, acetaldehyde, quinine, fluorescein, rhodamine B and rhodamine 6G was studied. The parameters selected were 4.0molL -1 sulphuric acid, 0.25mmolL -1 permanganate and 0.75molL -1 formaldehyde. Four quantitative parameters adjustable via software settings, two of them typically kinetic parameters, such as rate of the light-development reaction and rate of the light-decay reaction, and the other conventional parameters, such as maximum emission intensity and total emission area, were used to obtain linear calibration graphs with each measurement parameter. The detection limits ranged from 0.011 to 0.026μgmL -1 and R.S.D. values (n=10) of 1.21-3.93 at a 0.50μgmL -1 and 2.01-3.41 at a 1.60μgmL -1 concentration levels were obtained. The method was satisfactorily applied to the determination of captopril in pharmaceutical preparations.

A kinetic method has been developed for the determination of 1-naphthylacetic acid by means of micellar-stabilized room temperature phosphorescence (MSRTP) using the stopped-flow mixing technique. The main feature of this system is that it diminishes the time required for the deoxygenation of the micellar medium and for the phosphorescence development. Phosphorescence enhancers such thallium(I) nitrate, sodium dodecyl sulfate (SDS), and sodium sulfite were optimized to obtain maximum sensitivity. The pH was also optimized as it strongly affects the luminescent properties of 1-naphthylacetic acid. A pH of 6.6 was selected as adequate for the phosphorescence development. The kinetic curve of 1-naphthylacetic acid phosphorescence was scanned at lambda(ex) = 278 nm and lambda(em) = 490 nm, and the maximum rate of phosphorescence was taken as the analytical signal. This was obtained by calculating the maximum slope of the curve in an interval of 3.6 s as it provided a good noise-to-signal ratio. This method permitted the determination of 1-naphthylacetic acid throughout a concentration range of 100-1800 ng mL(-1) with high precision (relative standard error = 0.91% and relative standard deviation = 2.30%; 1-naphthylacetic acid concentration = 800 ng mL(-1)). According to the Clayton criterion, the detection limit was 45 ng mL(-1). The same limit resulted in 39.3 ng mL(-1) when the error propagation theory was applied. The applicability of the method was successfully demonstrated by determining 1-naphthylacetic acid in different kind of samples, such as phytosanitary products, soils, pears, and apples. Recovery values not significantly different from the nominal content or the spiked amount were found for these determinations.

The world's largest mercury mine is placed at Almadén, Spain. However, there is a lack of information about the environmental impact of these mining activities in the ecosystem that surrounds this area. The aim of this article is to document the concentration of mercury in waters, sediments and bivalves of the aquatic system impacted by historic mine wastes. Simultaneously, a comprehensive study has been undertaken to characterise this hydrosystem and to determine the influence of some major physico-chemical parameters on the fate of mercury. Samplings were carried out for the last few years. Concentration of mercury in waters ranged from not detectable to 20 microg/l. For the sediments study, samples have been taken both from contaminated and non-contaminated sites within the basin. The regional background mercury concentration is higher than values typically cited for natural backgrounds. At exposed sites the mercury concentrations between 5 and 1000 microg/g were measured. These values are one to four order of magnitude greater than regional background levels. In the comparison between the results obtained at the present moment and those available for the 1974-1977 period, a general diminution of mercury levels is observed. Mercury concentrations in fresh water bivalves ranged between 1 and 4 microg/g (d.w.), with around 30% as monomethylmercury. In the discussion of the implications for risk assessment data available for other areas affected both for mine activities and mercuriferous belt are included.

A selective and sensitive method for determining napropamide by room-temperature phosphorescence in SDS micelles is proposed and applied to the determination of this substance in a technical formulation and in spiked soil, pepper, and tomato samples. The use of phosphorescence enhancers such as sodium dodecyl sulfate (micellar agent), thallium (I) nitrate (external heavy atom), and sodium sulfite (deoxygenation agent) was studied and optimized to obtain maximum sensitivity. The determination was performed in 66 mM SDS, 30 mM thallium (I) nitrate, and 8 mM sodium sulfite. Taking into account both maximum phosphorescence intensity and the time required to reach that, a pH value of 7.2 was selected. After the samples were left standing at room temperature for 10 min, the phosphorescence was totally developed. The intensity was then measured at lambda(ex) = 282 nm and lambda(em) = 528 nm. The calibration graph was linear for 50-600 ng mL(-1) napropamide. The detection limit, according to the error propagation theory, was 16 ng mL(-1). The method has been demonstrated for the analysis of soils, peppers, and tomatoes, but, because of matrix interference, the method of standard additions was applied to determine napropamide in the vegetable samples. Recoveries from all these matrixes of added napropamide were near 100%.

A method for the determination of salsalate at concentrations between 0.10 and 1.00 mug ml(-1) by means of fluorescence spectrometry technique is proposed. Salsalate, lightly soluble in water, is totally extracted into chloroform. In this organic phase, the drug shows low fluorescence but when an alkaline medium is provided, salsalate undergoes a substantial increase of the fluorescent intensity. Thus, the determination is performed in a chloroformic medium, where pyrrolidine chloroformic solution is added to give the basic character. The fluorescence measurements to quantify salsalate are carried out in its fluorescent band centered at lambda(ex)=299 nm and lambda(em)=410 nm. The method was successfully applied to the determination of salsalate in authentic pharmaceutical preparations, urine and serum. Samples of these latter two matrices, urine and serum, are extracted into chloroform, using in the aqueous phase a pH 4.8, provided by adding acetic acid/sodium acetate buffer solution. Owing to matrix interference, the method of standard additions was used to determine salsalate in the serum. The sensitivity and repeatability achieved with the proposed method are adequate for the determination of salsalate in these matrices.