PubMed Health⌕ Search

Biomedical subjects

S Pinzauti

Publications and source records attributed to S Pinzauti.

At least 37 records · Page 2Linked to original sources
PubMed1994

High-performance liquid chromatographic determination of benzalkonium and naphazoline or tetrahydrozoline in nasal and ophthalmic solutions.

A high-performance liquid chromatographic method is described for the determination of benzalkonium chloride homologues and naphazoline nitrate or tetrahydrozoline hydrochloride in ophthalmic and nasal solutions. The technique involves a one-step dilution (1:5) for sample preparation and direct injection onto a 5 mm RP C-8 column. The mobile phase is acetonitrile-diluted acetic acid (80:20, v/v) with 6 mM tetramethylammonium bromide. Detection is carried out at 260 nm with a diode array. The method is rapid, specific, reproducible and is especially useful for quality control procedures.

Benzalkonium Compounds↗
PubMed1991

Characterization of Sanguinaria canadensis L. fluid extract by FAB mass spectrometry.

Positive-ion fast atom bombardment mass spectrometry was used for the rapid characterization of commercial Sanguinaria canadensis L. fluid extracts. Quaternary and non-quaternary benzophenanthridine alkaloids afford persistent peaks due to [M]+ and [M+H]+ ionic species, respectively, and their relative abundances are in good agreement with previously reported per cent analytical data. The procedure allowed sanguinarine, chelerythrine, chelirubine, sanguilutine, protopine, allocryptopine and the isomers sanguirubine and/or chelilutine to be effectively detected by means of persistent and intense peaks in all the samples examined.

Alkaloids↗
PubMed1990

High-performance liquid chromatographic determination of aliphatic thiols with aroylacrylic acids as fluorogenic precolumn derivatization reagents.

The use of the methyl ester of 4-(6-methoxynaphthalen-2-yl)-4-oxo-2-butenoic acid as a fluorogenic labelling reagent for the high-performance liquid chromatography (HPLC) of biologically important thiols (glutathione, cysteine, acetylcysteine, homocysteine, cysteamine, sodium 2-mercaptoethanesulphonate and thiola) was investigated. The compound reacts selectively and rapidly (10 min at ambient temperature and pH 7.5) with the thiols to give fluorescent adducts that can be separated by reversed-phase HPLC and detected fluorimetrically (lambda em = 450 nm; lambda em = 310 nm). Applications to the determination of L-cysteine and mesna in pharmaceutical formulations are described.

Chromatography, High Pressure Liquid↗
PubMed1990

Determination of flubendazole in pharmaceutical dosage forms by differential pulse polarography and UV spectroscopy.

A precise and accurate differential pulse polarographic method was developed for the determination of flubendazole in dosage forms without any prior extraction procedure of interference from the other stated ingredients. A UV spectroscopic procedure was also described and used as reference method. Analyses were generally performed at the 4 micrograms ml-1 flubendazole level. Flubendazole or its dosage forms were dissolved in 70% perchloric acid and diluted with a pH 2.6 sodium phosphate-citric acid buffer as polarographic supporting electrolyte or spectrophotometric solvent. The peak potential occurred at about -0.9 V (vs. Ag/AgCl reference electrode), depending on the pH of the assayed solution. The irreversible electrochemical reduction involved the transfer of two electrons. The UV absorption spectrum showed a sharp maximum at 237 nm with a specific extinction coefficient of 886. No advantage was found in the use of first and second-order derivative spectrophotometry.

Indicators and Reagents↗
PubMed1989

Determination of benzalkonium chloride in contact lens solutions by positive-ion fast atom bombardment mass spectrometry.

Under positive-ion fast atom bombardment (FAB) mass spectrometric conditions, benzalkonium chloride (BAK) afforded intense peaks at m/z 304 and 332, corresponding to the intact cations [M--Cl]+ of C12 and C14 homologues, respectively. The use of benzethonium chloride as an internal standard and thioglycerol as a FAB matrix allowed the direct and specific determination of the BAK content (0.004-0.020%) in commercial hard contact lens solutions through the individual assay of the two alkyl homologues. A linear relationship between the homologue concentration and the peak-area ratio was observed over the concentration range 3-180 micrograms ml-1.

Benzalkonium Compounds↗
PubMed1989

Determination of isosorbide-5-mononitrate in tablets by differential pulse polarography.

A differential pulse polarographic method requiring little sample separation was developed for the determination of isosorbide-5-mononitrate in tablet dosage form with the standard addition technique and without interference from common excipients. Britton-Welford buffer (pH 3.0) was used as the supporting electrolyte, the single peak occurring at -0.36 V vs. a reference Ag/AgCl electrode. The irreversible, diffusion controlled, two-electron reduction process at the dropping mercury electrode permits a precise and accurate determination of the active ingredient in the 0.4-20 microgram/ml concentration range.

Indicators and Reagents↗
PubMed1984

Direct quantitation of antiseptic quaternary ammonium compounds by fast atom bombardment mass spectrometry.

The medicinally important quaternary ammonium salts benzyldimethyltetradecylammonium chloride (BDTA), cetylpyridinium chloride and benzethonium chloride, all afford, under fast atom bombardment (FAB) mass spectrometric conditions, abundant and persistent [M-Cl]+ species usefully amenable to quantitative analysis with the aid of thioglycerol as a liquid FAB matrix. The use of BDTA as an internal standard allowed a direct, precise and accurate determination of cetylpyridinium and benzethonium chlorides, either as pure samples or in dosage forms, in the concentration range 0.05-2 mg/ml.

Journal Article↗
PubMed1983

Potentiometric titration of thiols, cationic surfactants and halides using a solid-state silver-silver sulphide electrode.

A rugged, low resistance silver-silver sulphide solid-state electrode for determining pharmaceuticals as authentic samples or in dosage forms by potentiometric titration is described. Sodium tetraphenylborate, mercury(II) acetate and silver nitrate (0.01) M were employed as titrants in the analysis of cationic surfactants (cetylpyridinium chloride, benzethonium chloride, benzalkonium chloride and chlorhexidine salts), antithyroid drugs (methimazole and propylthiouracil) or sodium halides respectively.

Journal Article↗