Search results for "Quantitative analysis."

Supercritical Fluid Extraction and Supercritical Fluid Chromatography of Vitamin E in Pharmaceutical Preparations

1999

Quantitative retention- and migration-toxicity relationships of phenoxy acid herbicides in micellar liquid chromatography and micellar electrokinetic…

2001

Abstract The need to obtain a tool for estimation of toxicity parameters for chemicals supports, the postulation of predictive models as an alternative to conventional classical assays. The use of micellar solutions of Brij35 as mobile phases in reversed phase liquid chromatography has proven to be valid in predicting some biological activities of different kinds of drugs. In this paper, the correlations between retention of phenoxy acids using different concentrations of Brij35 as micellar mobile phase in micellar liquid chromatography (MLC) and migration in micellar electrokinetic chromatography (MEKC) with several toxicity parameters are studied. Adequate correlations retention- and migr…

Kinetic-Spectrophotometric Determination of Primary and Secondary Amines by Reaction with 1-2 Naphthoquinone-4-Sulphonate.

1994

Abstract A kinetic-spectrophotometric method for the determination of primary and secondary amines is described. It is based on the coloured reaction of these amines with sodium 1,2 Naphthoquinone 4-sulphonate (NQS) in the presence of a non-ionic surfactant. For each determination the optimum conditions were studied and found to be as follows: pH 10.5. Carbonate-bicarbonate buffer 0.1M, Triton X-100 0.1%, Temperature 45°C, and NQS 6.4 × 10−3 M and interval of time 45–180s at wavelength 490 nm. The parameters used for the quantitative determinations are the reaction rate and the increase in the absorbance of the kinetic curves. This procedure has been applied to the determination of ephedrin…

Flow injection-spectrophotometric determination of metoclopramide hydrochloride.

1997

Abstract The determination of metoclopramide hydrochloride is spectrophotometrically determined by the Bratton-Marshall method in a flow injection assembly. The required nitrite is prepared on-line in the flow assembly by reducing a nitrate solution with the aid of a copperised cadmium solid-phase reactor. The calibration graph is linear over the range 0.5–85 mg l−1, with a relative standard deviation (RSD) of 0.89%, and sample throughput of 51 samples h−1. The method is easy and simple, and it is applied to determination of metoclopramide in some pharmaceutical formulations. The method eliminates the need for frequent preparation of unstable nitrite solutions.

Comparative Study on the Determination of Cephalexin in its Dosage Forms by Spectrophotometry and HPLC with UV-vis Detection

1997

This paper discusses the spectrophotometric determination of cephalexin as the intact cephalexin or as its acid-induced degradation product. Cephalexin can be determined in the range 1 × 10−5−18 × 10−5M with relative standard deviations of 5-1%. The limits of quantitation and detection were 10−5 and 0.3 × 10−5M, respectively. These procedures were compared with reversed-phase HPLC determination. No interference was observed in the presence of common pharmaceutical adjuvants. The H-point standard additions method was applied in order to correct for the possible presence of the cephalexin precursor, 7-aminocephalosporanic acid; this improves the selectivity of the UV-vis spectrophotometric me…

Spectrophotometric determination of nalidixic and pipemidic acids in a flow injection assembly with a solid-phase reactor as a highly stable reagent …

2001

Abstract The flow-injection spectrophotometric determination of nalidixic (I) and pipemidic (II) acids were carried out by reaction with Fe(III) ions entrapped in a polymeric material and filling a packed-bed reactor; the released Fe(III) complexed with the quinolone is monitored at 426 nm. The method worked with a high reproducibility, even when using different reactors, days and solutions. Selectivity of the procedure was tested with different foreign compounds found in human urine as well as in pharmaceutical formulations containing both quinolones; no relevant interferences were observed. The calibration graph for (I) was linear over the range 1–250 μg ml −1 with a relative standard dev…

Rapid and simultaneous high-performance liquid chromatography assay of polyamines and monoacetylpolyamines in biological specimens

2000

A rapid, resolutive and reproducible reversed-phase high-performance liquid chromatography (RP-HPLC) method was developed for polyamines and acetylpolyamines by adopting pre-column derivatization with benzoyl chloride. In a single run lasting less than 15 min ten polyamines were separated as well as traces of benzoic acid, methylbenzoate and benzoic anhydride. These contaminants, produced during the derivatization reaction, were almost all eliminated by washing steps envisaged in the same procedure. This simple and sensitive method can be applied to routine determination of polyamines in biological samples. A fine application of this procedure to the determination of endogenous content of p…

Combining workload balance and patient priority maximisation in operating room planning through hierarchical multi-objective optimisation

2022

Abstract Previous analysis suggested the opportunity to consider the preferences of different stakeholders (hospital, patients, doctors and nurses) through the adoption of both patient priority maximisation and workload balance as performance criteria. The aim of this paper is to develop an effective and efficient solution approach for the operating room planning and scheduling capable to take into account the patient priority maximisation and workload balance criteria at the same time. This work is inspired by the need of a deeper understanding of the quality of the solutions obtained when a combination of the two criteria leads the OR planning decisions. Starting from a hierarchical multi…

Producing social mobility. Class and Travel in the Romanian Novel 1901-1932

2020

The present article addresses the Romanian novelistic production between 1901 and 1932 in the attempt of identifying a series of patterns regarding the protagonists’ social mobility. Starting with the most mentioned destinations throughout the novels, I analyse how and why the different social classes travel and try to determine the landmarks between which they dispute their physical presence, on the one hand, and their aspirations, on the other. On this basis, the second part of the article conducts a quantitative analysis of the major means of transport in the period – the train, the tramway, the coach/carriage, the automobile, the aeroplane, the ship, and the waggon – and attempts to pin…

Furosemide assay in pharmaceuticals by Micellar liquid chromatography: study of the stability of the drug.

2000

A simplified high-performance liquid chromatographic procedure is described for the determination of furosemide (4-chloro-N-furfuryl-5-sulphamoylanthranillic acid), which makes use of UV detection, a C18, reversed-phase column, and micellar mobile phases of sodium dodecyl sulphate (SDS) and 1-propanol at pH 3 buffered with phosphate system. The most adequate experimental conditions to handle furosemide solutions in the analytical laboratory are studied. The mixture of furosemide and its degradation products which are formed upon light exposition was resolved with a mobile phase of 0.04 M SDS-2% propanol. Separation of furosemide from its common impurities and the hydrolytic product, 4-chlor…