A surface-enhanced infrared absorption spectroscopy (SEIRA) multivariate approach for atrazine detection.

A green, fast and effective multivariate method for the determination of atrazine (ATZ) was developed using conventional infrared equipment furnished with an attenuated total reflectance module (ATR-IR), providing limit of detection (LOD) and limit of quantification (LOQ) in the ranges from 1.9 to 4.6 µg/mL and from 5.

Underwater determination of calcium and strontium ions in oilfield produced water by laser-induced breakdown spectroscopy (LIBS).

Laser-induced breakdown spectroscopy (LIBS) was applied to the determination of scaling ions in oilfield-produced water employing underwater measurements. Initially, the stability of plasma was verified using four different optical setups and expansion of the laser beam, and a combination of an achromatic lens with a meniscus lens were necessary to stabilize the plasma. Preliminary experiments demonstrated that only the determinations of Ca(II) and Sr(II) ions were feasible while the signal for the Mg(II) ion was absent and the sensitivity for Ba(II) was very low.

A fluorescent magnetic core-shell nanosensor for detection of copper ions in natural waters.

A nanosensor based on magnetic core-shell nanoparticles functionalized with rhodamine derivative, N-(3-carboxy)acryloyl rhodamine B hydrazide (RhBCARB), using (3-aminopropyl)triethoxysilane (APTES) as a linker, has been synthesized for detection of Cu(II) ions in water. The magnetic nanoparticle and the modified rhodamine were fully characterized, showing a strong orange emission sensitive to Cu(II) ions. The sensor shows a linear response from 10 to 90 µg L, detection limit of 3 µg L and no interference of Ni(II), Co(II), Cd(II), Zn(II), Pb(II), Hg(II) and Fe(II) ions.

Biocompatibility analysis in subcutaneous tissue and physico-chemical analysis of pre-mixed calcium silicate-based sealers.

Objectives: To evaluate the biocompatibility, physical and chemical properties of three pre-mixed calcium silicate-based sealers and an epoxy resin-based material were assessed. Pre-mixed sealers supposedly obtain water from the root canal moist to hydrate and set.

Materials And Methods: Polyethylene tubes were filled with the materials Bio-C Sealer Ion+, Bio-C Sealer, EndoSequence BC Sealer and AH Plus Jet, or left empty and surgically implanted in the subcutaneous tissue of Wistar rats.

Analysis of sugars and sweeteners terahertz time-domain spectroscopy.

A THz-TDS spectrometer (terahertz time-domain spectroscopy) with ASOPS technology (asynchronous optical sampling) was employed in this study, aiming to explore the potential of the technique and to develop analytical applications for the identification of some saccharides. Analytical curves with linear responses were obtained in the saccharide concentration range from 1.7 to 11.

Detection of Low Lithium Concentrations Using Laser-Induced Breakdown Spectroscopy (LIBS) in High-Pressure and High-Flow Conditions.

This paper describes the effects of laser pulse rate and solution flow rate on the determination of lithium at high pressure for water and 2.5% sodium chloride solutions using laser-induced breakdown spectroscopy (LIBS). Preliminary studies were performed with 0-40 mg L Li solutions, at ambient pressure and at 210 bar, and in static and flowing (6 mL · min) regimes, for a combination of four different measurement conditions.

Development of a reusable fluorescent nanosensor based on rhodamine B immobilized in Stöber silica for copper ion detection.

This work has the goal of developing and evaluating a reusable fluorescent nanosensor for detection of Cu(ii) ion in aqueous solution, based on the immobilization of rhodamine B in silica nanoparticles prepared according to a modified Stöber method. In order to do this, a standard ammonium hydroxide ethanolic solution was mixed to ethanol under constant stirring, followed by the addition of tetraethoxysilane (TEOS). To immobilize the fluorescent reagent in the silica nanoparticles, rhodamine B ethanolic solution was added to the reacting mixture at different times (2; 3; 4 and 5 h) after starting the synthesis (which always lasts 7 h).

Depleting high-abundant and enriching low-abundant proteins in human serum: An evaluation of sample preparation methods using magnetic nanoparticle, chemical depletion and immunoaffinity techniques.

The efficiency of three different depletion methods to remove the most abundant proteins, enriching those human serum proteins with low abundance is checked to make more efficient the search and discovery of biomarkers. These methods utilize magnetic nanoparticles (MNPs), chemical reagents (sequential application of dithiothreitol and acetonitrile, DTT/ACN), and commercial apparatus based on immunoaffinity (ProteoMiner, PM). The comparison between methods shows significant removal of abundant protein, remaining in the supernatant at concentrations of 4.

A Simple Device for Lens-to-Sample Distance Adjustment in Laser-Induced Breakdown Spectroscopy (LIBS).

A simple device based on two commercial laser pointers is described to assist in the analysis of samples that present uneven surfaces and/or irregular shapes using laser-induced breakdown spectroscopy (LIBS). The device allows for easy positioning of the sample surface at a reproducible distance from the focusing lens that conveys the laser pulse to generate the micro-plasma in a LIBS system, with reproducibility better than ±0.2 mm.

iHEART: a miniaturized near-infrared in-line gas sensor using heart-shaped substrate-integrated hollow waveguides.

A novel heart-shaped substrate-integrated hollow waveguide (hiHWG) was integrated with a near-infrared micro-spectrometer (μNIR) for sensing natural gases, resulting in an ultra-compact near-infrared gas sensing system - iHEART. The iHEART system was evaluated using two different μNIR spectrometers, and the performance was compared with a laboratory NIR spectrometer for gas analysis based on an acousto-optic tunable filter (AOTF). The spectral data were pre-processed using the 1(st) derivative Savitzky-Golay algorithm, and then used for establishing multivariate regression models based on partial least squares (PLS).

Sensing hydrocarbons with interband cascade lasers and substrate-integrated hollow waveguides.

Tunable diode laser absorption spectroscopy (TDLAS) is an excellent analytical technique for gas sensing applications. In situ sensing of relevant hydrocarbon gases is of substantial interest for a variety of in-field scenarios including environmental monitoring and process analysis, ideally providing accurate, molecule specific, and rapid information with minimal sampling requirements. Substrate-integrated hollow waveguides (iHWGs) have demonstrated superior properties for gas sensing applications owing to minimal sample volumes required while simultaneously serving as efficient photon conduits.

Photostable, Oxygen-Sensitive Optical Probe Based on a Homonuclear Terbium(III) Complex Covalently Bound to Functionalized Polydimethylsiloxane.

A new oxygen-sensitive optical probe based on the [Tb(3,5-dcba) ]⋅1/2 H O (3,5-dcba=3,5-dichlorobenzoate) complex, which is chemically attached to a phosphine-oxide-functionalized polydimethylsiloxane is presented. The hybrid material shows green emission and transparency in the visible range. The optically sensitive probe is photostable under excitation at 350 nm and shows the highest oxygen sensitivity, I /I equal to 8.

Analysis of immersed silica optical microfiber knot resonator and its application as a moisture sensor.

An embedded silica optical microfiber knot resonator humidity sensor is presented. As silica has a poor response to environmental humidity changes, a surrounding layer of Nafion is used as a transducer. Spectral characterization and also a procedure to determine the coupling and total loss coefficients are presented.

Monitoring of hydrogen sulfide via substrate-integrated hollow waveguide mid-infrared sensors in real-time.

Hydrogen sulfide is a highly corrosive, harmful, and toxic gas produced under anaerobic conditions within industrial processes or in natural environments, and plays an important role in the sulfur cycle. According to the U.S.

Real-time monitoring of ozone in air using substrate-integrated hollow waveguide mid-infrared sensors.

Ozone is a strong oxidant that is globally used as disinfection agent for many purposes including indoor building air cleaning, during food preparation procedures, and for control and killing of bacteria such as E. coli and S. aureus.

Fluorescent ion-imprinted polymers for selective Cu(II) optosensing.

This paper describes the synthesis and characterization of a fluorescent ion-imprinted polymer (IIP) for selective determination of copper ions in aqueous samples. The IIP has been prepared using a novel functional monomer, 4-[(E)-2-(4'-methyl-2,2'-bipyridin-4-yl)vinyl]phenyl methacrylate (abbreviated as BSOMe) that has been spectroscopically characterized in methanolic solution, in the absence and in the presence of several metal ions, including Cd(II), Cu(II), Hg(II), Ni(II), Pb(II), and Zn(II). The stability constant (2.

Simultaneous determination of copper, mercury and zinc in water with a tailored fluorescent bipyridine ligand entrapped in silica sol-gel.

A novel fluorescent ligand, (4-[(E)-2-(4'-methyl-2,2'-bipyridin-4-yl)vinyl]phenol) (abbreviated BSOH), has been designed and prepared for simultaneous determination of heavy metals in water. Its photophysical and photochemical properties in the absence and in the presence of Cd(II), Cu(II), Hg(II), Ni(II) and Zn(II) were determined, and the respective complexation constants (7.4 × 10(3)-2.

A microfluidic device with integrated fluorimetric detection for flow injection analysis.

This work describes the development of flow analysis microsystems with integrated fluorimetric detection cells. Channels (width of 300-540 microm and depth of 200-590 microm) were manufactured by deep-UV lithography in urethane-acrylate (UA) resin. Plastic optical fibers (diameter of 250 microm) were coupled to a 2.

Assessment of infrared spectroscopy and multivariate techniques for monitoring the service condition of diesel-engine lubricating oils.

This paper presents two methodologies for monitoring the service condition of diesel-engine lubricating oils on the basis of infrared spectra. In the first approach, oils samples are discriminated into three groups, each one associated to a given wear stage. An algorithm is proposed to select spectral variables with good discriminant power and small collinearity for the purpose of discriminant analysis classification.

Application of amperometric sol-gel biosensor to flow injection determination of glucose.

A glucose biosensor with enzyme immobilised by sol-gel technology was constructed and evaluated. The glucose biosensor reported is based on encapsulated GOX within a sol-gel glass, prepared with 3-aminopropyltriethoxy silane, 2-(3,4-epoxycyclohexyl)-ethyltrimetoxy silane and HCl. A flow system incorporating the amperometric biosensor constructed was developed for the determination of glucose in the 1x10(-4)-5x10(-3) moll(-1) range with a precision of 1.

Design and development of a multichannel potentiometer for monitoring an electrode array and its application in flow analysis.

A versatile potentiometer that works with electrode arrays in flow injection and/or monosegmented flow systems is described. The potentiometer is controlled by a microcomputer that allows individual, sequential multiplexed or random accesses to eight electrodes while employing only one reference electrode. The instrument was demonstrated by monitoring an array of seven flow-through ion-selective electrodes for Ag+ and for three electrodes for Cl(-), Ca2+ and K+.

Simultaneous determination of methanol and ethanol in gasoline using NIR spectroscopy: effect of gasoline composition.

Near infrared (NIR) spectroscopy was employed for simultaneous determination of methanol and ethanol contents in gasoline. Spectra were collected in the range from 714 to 2500 nm and were used to construct quantitative models based on partial least squares (PLS) regression. Samples were prepared in the laboratory and the PLS regression models were developed using the spectral range from 1105 to 1682 nm, showing a root mean square error of prediction (RMSEP) of 0.

Construction and evaluation of a flow injection micro-analyser based on urethane-acrylate resin.

A flow injection micro-analyser with an integrated injection device and photometric detection is described. Channels measuring 205-295 microm depth by 265-290 microm maximum width were manufactured by deep UV lithography on two layers of urethane-acrylate oligomers-based photoresist. Hypodermic syringe needles (450 microm diameter) were connected to the channels for introduction of solutions into the system.

A simple method for water discrimination based on an light emitting diode (LED) photometer.

This work describes the use of a multi-LED photometer for discrimination of mineral water samples, employing chromogenic reagents and chemometric techniques. Forty-five water samples (including 7 different brands of mineral water and samples of deionised, distilled and tap waters) were analysed in a monosegmented flow system, using three different chromogenic reagents (murexide, PAR and eriochrome black T) in a pH 10.0 NH3/NH4(+) buffer in separate injections.