Biomedical subjects

A Segura Carretero

Publications and source records attributed to A Segura Carretero.

12 recordsLinked to original sources

PubMed2005

Interfacing capillary electrophoresis and surface-enhanced resonance Raman spectroscopy for the determination of dye compounds.

The at-line coupling of capillary electrophoresis (CE) and surface-enhanced resonance Raman spectroscopy (SERRS) was optimized for the separation and subsequent spectroscopic identification of charged analytes (dye compounds). Raman spectra were recorded following deposition of the electropherogram onto a moving substrate. To this end a new interface was developed using a stainless steel needle as a (grounded) cathode. The outlet end of the CE capillary was inserted into this metal needle; CE buffer touching the needle tip served as the electrical connection for the CE separation. A translation table was used to move the TLC plate at a constant speed during the deposition. The distance between the tip of the fused silica column and the TLC plate was kept as small as possible in order to establish a constant bridge-flow, while avoiding direct contact. The dyes Basic Red 9 (BR9), Acid Orange 7 (AO7) and Food Yellow 3 (FY3) were used as test compounds. After CE separation in a 20 mM borate buffer at pH 10, after deposition, concentrated silver colloid was added to each analyte spot, followed by irradiation with 514.5 nm light from an argon ion laser to record the SERRS signal using a Raman microscope. Different types of silver colloids were tested: Lee-Meisel type (citrate), borate, and gold-coated silver. BR9 (positively charged) gave much more intense SERRS spectra than the two negatively charged dyes. For BR9 and AO7 the citrate-coated Lee-Meisel colloid yielded the most intense SERRS spectra. The CE-SERRS system was used to separate and detect the negatively charged dyes. Silver colloid and nitric acid (to improve adsorption) were added post-deposition. Even though their chemical structures are very similar, AO7 and FY3 could be readily distinguished based on their SERRS spectra. The limits of detection (S/N = 3) of the CE-SERRS system ranged from 6.7 x 10(-5) M (2.6 x 10(-12) mol injected) for FY3 down to 1.8 x 10(-6) M (7.0 x 10(-14) mol injected) for BR9.

Journal Article↗

PubMed2005

A fluorescence optosensor for analyzing naphazoline in pharmaceutical preparations. Comparison with other sensors.

We have developed an optical sensor for determining and quantifying naphazoline (NPZ) based on its inherent fluorescence property. We have placed a non-ionic-exchanger solid support (Amberlite XAD-7) in a flow cell in the light path of the excitation beam and the fluorescence signal for NPZ is continuously monitored at lambda(exc/nm)=294/306 nm. The response time for this sensor is acceptably fast, 80s, obtaining a detection limit of 2.6 ng mL(-1) with standard deviations of 2.0% at 125 ng mL(-1). This device has been satisfactorily applied to two commercial formulations and its selectivity has been demonstrated with an interference study. The advantages have been compared with the only published sensor for determining NPZ in pharmaceutical preparations and with other analytical methods in the literature.

Adrenergic alpha-Agonists↗

PubMed2004

Determination of phytohormones of environmental impact by capillary zone electrophoresis.

A test mixture of five phytohormones [naphthaleneacetic acid (NAA), naphthoxyacetic acid (NOA), indoleacetic acid (IAA), indolebutyric acid (IBA), and indolepropionic acid (IPA)] was investigated. These compounds were cleanly separated with good resolution by capillary zone electrophoresis with a UV diode array detector using 20 mM sodium phosphate buffer (pH 7.25). The lowest detection limit was obtained for IPA (0.45 mg L(-)(1) or 0.005 mg kg(-)(1)) and the highest for NAA (1.04 mg L(-)(1) or 0.014 mg kg(-)(1)). The method has been applied for tomato samples fortified with the five phytohormones using a liquid-liquid extraction procedure, obtaining recovery percentages ranging from 91 to 109.0%.

Agriculture↗

PubMed2003

Sensitive and simple determination of the vasodilator agent dipyridamole in pharmaceutical preparations by phosphorimetry.

The applicability of heavy atom-induced room-temperature phosphorescence to pharmaceutical samples is demonstrated in this work. Thus a new, simple, rapid, and selective phosphorimetric method for dipyridamole determination is proposed. The phosphorescence signals are a consequence of intermolecular protection when analytes are exclusively in the presence of heavy atom salts and sodium sulfite as an oxygen scavenger to minimize RTP quenching. The determination was performed in 0.1 mol L(-1) thallium(I) nitrate and 8 mmol L(-1) sodium sulfite at a measurement temperature of 20 degrees C. The phosphorescence intensity was measured at 635 nm, with excitation at 305 nm. Phosphorescence was easily developed; a linear concentration range was obtained between 0 and 100 ng mL(-1) with a detection limit of 940 ng L(-1), an analytical sensitivity of 2.5 ng mL(-1), and a standard deviation of 2.7% at 60 ng mL(-1) concentration. The method has been successfully applied to the analysis of dipyridamole in a unique Spanish commercial formulation containing 100 ng mL(-1) per capsule. The recovery was 101.6% with 6.5% standard deviation of analytical measurement. The method using the standard addition methodology has been validated.

Calibration↗

PubMed2003

Determination of imidacloprid and its metabolite 6-chloronicotinic acid in greenhouse air by application of micellar electrokinetic capillary chromatography with solid-phase extraction.

A method is described for the analysis of the insecticide imidacloprid [1-(6-chloro-3-pyridylmethyl)-N-nitroimidazolidin-2-ylideneamine] and its metabolite 6-chloronicotinic acid by micellar electrokinetic chromatography with diode-array detection at 270 and 227 nm, respectively. The best results were obtained using sodium dodecyl sulphate at a concentration of 60 mM and a running buffer of NH4Cl/NH3 at 15 mM (pH 8.5). The selection of instrumental parameters such as voltage at 30 kV with an injection time of 20 s gave the best resolution with an analysis time of less than 6 min. The method yields similar sensitivity for the parent compound and for the metabolite, with detection limits of 0.71 and 1.18 microg/ml for imidacloprid and 6-chloronicotinic acid, respectively. The sampling and analysis of these two pesticides in greenhouse air was carried out using personal samplers connected to XAD-2 cartridges as sampling media, investigating the dissipation of analytes in a 24-h period after their application.

Agriculture↗

PubMed2003

A sensitive fluorescence optosensor for analysing propranolol in pharmaceutical preparations and a test for its control in urine in sport.

We describe a simple and selective method for analysing propranolol and a sensitive test for its control in urine. A flow-through fluorescence optosensor based on on-line immobilization in a non-ionic-exchanger (Amberlite XAD-7) solid support in a continuous flow was used in both cases. Determination was made in 5 mM H(2)PO(4)(-)/HPO(4)(2-) buffer solution at pH 6 at a working temperature of 20 degrees C. Fluorescence intensities were measured at lambda(ex/em) = 300/338 nm with a response time of 80 s, thus obtaining a linear concentration range of between 0 and 250.0 ng ml(-1) with a detection limit of 1.3 ng ml(-1), an analytical sensitivity of 6.0 ng ml(-1) and a standard deviation of 2.40% at a 150 ng ml(-1) concentration level for propranolol. We also propose a test to detect propranolol in urine with a linear concentration range between 0 and 100.0 ng ml(-1), a detection limit of 0.2 ng ml(-1), an analytical sensitivity of 1.0 ng ml(-1), and a standard deviation of 0.84% at a 75 ng ml(-1) concentration level. The effect of proteins presents in urine samples were evaluated. The two proposed methods were satisfactorily applied to commercial formulations and urine samples respectively.

Adrenergic beta-Antagonists↗

PubMed2003

Simultaneous determination of the pesticides carbaryl and thiabendazole in environmental samples by a three-dimensional derivative variable-angle and a synchronous room-temperature phosphorescence spectroscopy.

A three-dimensional derivative variable-angle synchronous scanning (DVASS) and a synchronous scanning (SS) heavy-atom room-temperature phosphorimetry (HAI-RTP) method are reported, for the first time, to identify and quantify the spectral overlapping phosphorescent pesticides thiabendazole (TBZ) and carbaryl (CBL). These pesticides are widely used in agriculture. The phosphorescence emission of the two compounds was obtained using sodium sulfite as the O2 scavenger and an external heavy atom salt. A careful selection of these experimental variables has been carried out. The increase of selectivity afforded by the DVASS and the SS methodology permitted the demonstration of its applicability to the simultaneous determination of phosphorescent signals of these two pesticides with overlapping spectral profiles. Limits of detection ranged between 1.4 ng/mL for TBZ and 1.7 ng/mL for CBL. The proposed method has been satisfactorily applied to the analysis of both pesticides in different types of water samples.

Carbaryl↗

PubMed2002

Simple determination of propranolol in pharmaceutical preparations by heavy atom induced room temperature phosphorescence.

The applicability of heavy atom induced room temperature phosphorescence in real samples is demonstrated in this work. In this methodology only two reagents, potassium iodide as heavy atom salt and sodium sulphite as oxygen scavenger, were used to obtain phosphorescent signal of propranolol in solution. Thus a new simple, rapid and selective phosphorimetric method is proposed for propranolol determination in pharmaceutical preparations. The phosphorescence intensity was measured at 492 nm exciting at 294 nm. Phosphorescence was fully developed instantly, obtaining a linear concentration range between 0 and 500 ng ml(-1) with a detection limit of 14.4 ng ml(-1), an analytical sensitivity of 6.7 ng ml(-1) and a standard deviation of 1.4% at a 300 ng ml(-1) concentration level. The method has been successfully applied to the analysis of propranolol in an antidepressive pharmaceutical preparation and it was validated using standard addition methodology.

Luminescent Measurements↗

PubMed1999

Fluorimetric determination of procaine in pharmaceutical preparations based on its reaction with fluorescamine.

A simple spectrofluorimetric analysis of a local anaesthetic named procaine using a specific labelling reagent for primary amino groups, has been developed. Because procaine shows very weak native fluorescence, the technique of spectrofluorimetry has been very much limited for its determination. A detail study of the variables affecting the derivatisation reaction (pH, fluorescamine (FC) concentration, temperature, reaction time), have minuciously been studied. The minimum detectable quantity is estimated as 7.7 ng ml(-1), with a relative standard deviation of 2.16% (ten determinations) for a procaine concentration of 100 ng ml(-1). The present method can be employed for the analysis of procaine by direct fluorescence measurements, without the interference from other compounds. The applicability of the present methodology have been demonstrated analysing three pharmaceutical preparations containing the analyte with satisfactory results.

Anesthetics, Local↗

PubMed1998

Room-temperature phosphorimetric method for the determination of the drug naphazoline in pharmaceutical preparations.

A selective and sensitive micelle-stabilized room-temperature phosphorimetric (MS-RTP) method for the determination of naphazoline in pharmaceutical preparations is described. The method is based on obtaining a phosphorescence signal from naphazoline using a micellar agent (sodium dodecyl sulfate), a heavy atom salt (TINO3) and a deoxygenation agent (Na2SO3). Optimization of the various conditions permitted the establishment of an MS-RTP method for naphazoline determination with a detection limit of 64.2 ng ml-1 and a relative standard deviation of 3.74% at the 500 ng ml-1 level. The method was applied to the analysis of pharmaceutical preparations.

Adrenergic alpha-Agonists↗

PubMed1995

Micellar-enhanced synchronous-derivative fluorescence determination of derivatized folic acid in pharmaceutical preparations.

A sensitive and inexpensive micellar-enhanced synchronous-derivative spectrofluorimetric method is described for the determination of folic acid in pharmaceutical preparations. The method is based upon derivatization of the vitamin with fluorescamine in acid solution and enhancement of the fluorescence with a surfactant. Linear fluorimetric analytical curves were obtained for folic acid concentrations of 0.05-6 micrograms ml-1 (detection limit 0.012 micrograms ml-1); the RSD for 1 micrograms ml-1 of folic acid was 2.82%. The method has been applied to the determination of folic acid synthetic mixtures and pharmaceutical preparations.

Detergents↗

PubMedDate not supplied

Application of partial least-squares calibration to phosphorimetric data for determination of polycyclic aromatic hydrocarbons in spiked environmental samples.

A partial least-squares calibration method is proposed, for the first time, for phosphorescence signals. The proposed method is based on the determination of phenanthrene, fluoranthene, and benz[a]anthracene by room temperature phosphorimetry, using microemulsion solutions. The emission and first-derivative emission spectra of the ternary mixtures were tested to perform the calibration matrix. Improved recoveries were found for the prior differentiation step in the analysis of ternary mixtures of these polycyclic aromatic hydrocarbons in road dust samples. The proposed method yielded recoveries ranging from 93.2 to 115.3%, with relative standard deviations of < 6.8%.

Benz(a)Anthracenes↗