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Biomedical subjects

M Valcárcel

Publications and source records attributed to M Valcárcel.

At least 19 recordsLinked to original sources
PubMed1992

Diagnostic exposure in a primary care clinic during pediatric training.

A retrospective and descriptive study was done in a general pediatric training site with the purpose of identifying the diagnoses to which the trainees have been exposed, as well as the changes in the pattern of these diagnoses. The number of patient-doctor contacts, type of patient visit, and frequency of diagnoses were compared. A total of 66,054 patient-doctor contacts occurred during the years 1979 to 1989, comprising 79.6 percent scheduled health visits and 20.4 percent emergency visits. The main diagnoses were: healthy child/adolescent (HV), well baby (WB), upper respiratory infection, skin diseases, bronchial asthma, acute gastroenteritis, otitis media, anemia, incomplete immunization, psychosocial problems, nutritional/linear growth problems, psychosomatic disturbances, parasitosis, and pneumonia. There was a significant decrease (P < .005) in the diagnosis of infectious diseases and a significant increase (P < .005) in the proportion of WB and HV. The latter were the two most common diagnoses in the year 1989.

Acute Disease↗
PubMed1990

Gas chromatographic determination of phenol compounds with automatic extraction and derivatization.

Two gas chromatographic procedures for the determination of a variety of substituted phenols in water samples are described. The phenols were extracted or extracted-derivatized by using a continuous liquid-liquid extraction-derivatization system and quantified with flame ionization detection. Ethyl acetate was found to be the most efficient solvent for phenols whereas n-hexane yielded essentially the same recoveries for derivatized phenols. Between 0.1 and 300 mg/l of the different phenols can be detected with a relative standard deviation 1.1 and 3.7%. The acetate esters of six phenols were formed by the direct addition of acetic anhydride to the organic extractant. The stable acetate esters thus formed were isolated by using a standard dimethyl polysiloxane gas chromatographic column.

Chlorophenols↗
PubMed1990

Determination of alanine aminotransferase in human serum in an open-closed flow injection configuration.

Open-closed flow injection systems allow the development of methods based on multidetection by using conventional detectors. The methods proposed here for the determination of alanine aminotransferase (ALT) utilize a photometric detector included in the closed circuit, which allows one to perform fixed-time and reaction-rate measurements whose sensitivity can be increased by using the sum of the analytical signals. The methods, with determination ranges between 1 and 500 U l-1 of ALT, feature sampling frequencies up to 60 h-1. Their application to serum samples provided excellent results, with recoveries between 95 and 106% and averaging at 99.9%.

Alanine Transaminase↗
PubMed1990

Automation of pharmaceutical dissolution testing by flow injection analysis.

The different types of instruments used for monitoring pharmaceutical dissolution testing are presented. Their features and the need for automation are critically discussed. The advantages of flow injection analysis in this respect are illustrated by a variety of examples clearly showing its adaptability to the different problems posed by other automatic and non-automatic alternatives.

Autoanalysis↗
PubMed1990

Indirect continuous automatic determination of pharmaceuticals by atomic absorption spectroscopy.

The implementation of continuous separation techniques such as precipitation, liquid-liquid and solid-liquid extraction in FIA manifolds coupled on-line with an atomic absorption spectrometer for the determination of active components (sulphonamides, local anaesthetics, amphetamines, benzodiazepines, chloramphenicol and methadone) in pharmaceuticals and biological fluids is systematically described. The basic features of the analytical methodologies described (sensitivity, selectivity, precision and rapidity) are also discussed and critically compared.

Amphetamines↗
PubMed1990

Use of photochemical reactions in flow injection: determination of oxalate in urine.

The use of photochemical reactions in flow injection (FI) is reported. The irradiation of an FI reactor with a suitable source facilitates the development of the iron(III)-oxalate reaction, allowing the amperometric determination of the anion in the range 1.0-13.0 micrograms ml-1, with a relative standard deviation of 1.1% and a sampling frequency of 40 h-1. The proposed method was applied successfully to the determination of oxalate in urine samples.

Humans↗
PubMed1989

Flow injection analysis of pharmaceuticals.

An overview of the most representative problems solved by flow injection analysis (FIA) in drug analysis is presented. Different aspects of this technique which can be manipulated with specific purposes are discussed and special emphasis is placed on the possibilities of FIA in dissolution test control.

Chemistry, Pharmaceutical↗
PubMed1987

Determination of total cholesterol in serum by flow injection analysis with immobilized enzymes.

Several photometric and fluorimetric methods are proposed for the determination of cholesterol by use of enzymes immobilized on controlled-pore glass and the normal and stopped-flow injection modes, achieving linear ranges of the calibration curves between 26-776 mumol/l and 5-265 mumol/l with excellent regression coefficients and good coefficients of variation. The methods have been applied to the determination of this analyte in serum with excellent results.

Cholesterol↗
PubMed1987

Direct quantification of coproporphyrins and uroporphyrins in urine by derivative synchronous fluorescence spectroscopy.

The second-derivative synchronous fluorescence spectroscopic technique is applied to the simultaneous and direct assay of coproporphyrins and uroporphyrins in human urine. This technique resolves the overlapping conventional spectra, obviating the need for pre-analysis sample separation techniques, and measurements can be made in a single scan. The amplitudes of the derivative peaks are linearly related to uroporphyrin (0.4 to 300 micrograms/L) and coproporphyrin (0.4 to 250 micrograms/L) concentrations. The detection limit for both porphyrins is 0.1 microgram/L. Analytical recoveries range between 98 and 101%. Within- and between-assay CVs are reported. Results for 24-h urine specimens correlated well with those obtained by an extraction-ion-exchange chromatography combined method. The proposed method is inexpensive and requires no sophisticated detection equipment.

Coproporphyrins↗