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Biomedical subjects

J L Lima

Publications and source records attributed to J L Lima.

8 recordsLinked to original sources
PubMed1991

Flow injection system based on the sandwich technique for saving expensive reagents.

We report the application of a sandwich technique in flow injection systems which afford low consumption of expensive reagents and two reagent recirculation systems. The potential applicability of the technique thus developed was assessed by determining glucose in serum samples by the enzymatic glucosidase/peroxidase method. It was possible to perform up to 450 determinations with the same amount of reagent used to perform 50 determinations by batch procedures. The sampling rate was 80 determinations per hour with a 0.9% relative standard deviation.

Blood Glucose↗
PubMed1991

Vitamins B1 and B6 tubular electrodes as FIA detectors; their use in the analysis of pharmaceutical products.

Ion-selective electrodes without an inner reference solution and tubular potentiometric detectors for the determination of vitamins B1 and B6 in pharmaceutical preparations by flow injection analysis (FIA) are reported. The membranes were prepared with the vitamin tetra(2-chlorophenyl)borate (TCPB) dissolved in o-nitrophenyloctyl ether (o-NPOE) and immobilized on PVC. Intrinsic behaviour of the tubular detectors was assessed using a low-dispersion single-channel FIA manifold and was compared with conventionally-shaped electrodes using the same membrane. Data obtained in the determination of vitamins B1 and B6 in pharmaceutical preparations with a double channel flow injection manifold incorporating the tubular detectors are presented and compared with those obtained by the U.S. Pharmacopeia method and by direct potentiometry with conventionally-shaped electrodes.

Electrodes↗
PubMed1991

[Benzoate determination in medicinal syrups with a PVC membrane ion selective electrode without inner reference solution].

Two electrodes sensitives to benzoate ion, without inner reference solution, in which tetraoctylammonium benzoate in dibutylphtalate (type A) or 2-nitrophenyloctylether (type B) immobilized in PVC are used in membranes, applied on a conductive support, were prepared. The response characteristics and behaviour of this low-cost electrodes are presented. The analytical application possibilities are discussed and shown as practical examples on analyses of the ion in medicals syrups.

Benzoates↗
PubMed1989

Solid-state PVC flow-through benzoate electrode.

A general construction procedure for conventional shape ion-selective electrodes based on a conductive support prepared with a mixture of a non-conductive epoxy and graphite was used in the preparation of a flow-through benzoate electrode to be used as potentiometric detector in flow injection analysis manifolds. The membranes were prepared from tetraoctylammonium benzoate in o-nitrophenyloctylether immobilized on PVC. The results of the assessment of the tubular electrodes behaviour in low dispersion manifolds against that of conventional electrodes with the same membrane are reported. Data obtained with a double-channel flow injection manifold incorporating these tubular detectors for benzoate determinations in several commercially available pharmaceutical preparations are also presented.

Benzoates↗
PubMed1989

Flow injection analysis of inorganic cationic species in serum and urine.

This paper describes three flow injection analysis (FIA) systems for the automatic determination of sodium, potassium, lithium, calcium, magnesium, zinc, copper and iron in certain biological fluids and compares the results obtained to those of flame photometry and atomic absorption spectrometry. The set-ups were designed to allow the samples to be prepared in the same manner as that used for batch procedures with the same analytical instrument. For determinations requiring a high sample dilution, it was found of definite advantage to split the stream and pass large amounts of liquid through the detection systems. The comparison of the results obtained by FIA and conventional methods yielded correlation coefficients in the range 0.990 to 0.999. The proposed methodology show good precision, with variation coefficients between 0.5% to 5%.

Calcium↗
PubMedDate not supplied

PVC membrane electrode without inner reference solution for the direct determination of ephedrine in pharmaceutical preparations.

A PVC membrane electrode, without inner reference solution, based on an ion association extraction system responding to ephedrine is described. It incorporates an ephedrine-tetrakis (4-chlorophenyl)borate ion-pair complex in 2-nitrophenyloctyl ether. The prepared electrode exhibits a near Nernstian response (57.5 mV per decade) over the concentration range of 2 x 10(-5)-10(-1) M ephedrine in solutions of pH 2.5-9. The reproducibility of the electrode potentials were +/- 1 mV by day during at least 6 months. Response time was about 6 s for ephedrine concentrations between 10(-5) and 10(-1) M. Determinations of ephedrine in pharmaceutical preparations (tablets, nasal drops and syrups) by direct potentiometry gave an average recovery of 99.1% (w/w) and a mean standard deviation of 1.9% (w/w).

Chemistry, Pharmaceutical↗