Search results for "Liquid Chromatography"
showing 10 items of 942 documents
Pharmaceuticals in processing of municipal sewage sludge studied by grab and passive sampling
2018
Abstract Concentrations of pharmaceuticals, consisting of four anti-inflammatory and one antiepileptic drug, were studied in the aqueous and solid phase of municipal sewage sludge, collected from a wastewater treatment plant (WWTP) in central Finland. The samples included untreated municipal sludge from the biological wastewater treatment, digested sludge and sludge before and after composting. First, samples were taken as grab samples to study the bioavailable part in aqueous phase but also the part in solid fraction. Later, the long-term concentrations were studied by passive sampling with styrene divinylbenzene-reverse phase sulfonated (SDB-RPS) disks. In the untreated solid sludge, the …
Synthesis of fluorine-18 labeled sulfonureas as ?-cell imaging agents
2001
Tolbutamide (1) and glyburide (7) are hypoglycemic drugs used to stimulate insulin secretion in type 2 diabetic patients. We have synthesized their fluorine-18 labeled analogs, 1-[(4-[ 18 F]fluorobenzenesulfonyl)]-3-butyl]urea (p-[ 18 F]fluorotolbutamide, 3a) and N-{4-[β-(2-[ 18 F]fluoroethoxybenzene carboxamido)ethyl]benzenesulfonyl)-N'-cyclohexylurea (2-[ 18 F]fluoroethoxyglyburide, 6a) as β-cell imaging agents. Compound 3a was synthesized via two approaches: One-step synthesis via nucleophilic substitution of p-nitrotolbutamide (2) with K[ 18 F]/Kryptofix 2.2.2 in either CH 3 CN or DMSO gave a complicated mixture; a two-step synthesis via preparation and reaction of 4-[ 18 F]fluorobenzen…
Compatibility of irinotecan-loaded DC Bead with different volumes and types of non-ionic contrast media.
2015
Objectives Irinotecan-loaded microspheres are used for simultaneous embolisation and chemotherapy of liver metastases of colorectal carcinoma. The aim of the study was to evaluate the compatibility of recently introduced DC Bead M1 (bead size 70–150 µm) loaded with irinotecan after admixture with different types and volumes of non-ionic contrast media over a maximum period of 24 h and storage at room temperature. Methods Test suspensions were prepared by loading 2 mL DC Bead M1 with 100 mg irinotecan within 2 h. The loading efficiency was determined by measuring the concentrations of irinotecan in the excess solutions via a reversed phase high pressure liquid chromatography (RP-HPLC) assay …
High performance liquid chromatography analysis of tear protein patterns in diabetic and non-diabetic dry-eye patients.
2001
To analyze and compare the high performance liquid chromatography (HPLC) runs of tear proteins from diabetic (DIDRY) and non-diabetic (DRY) dry-eye patients, and healthy subjects (CTRL). The patterns were analyzed using multivariate statistical methods.Tears (total 56 eyes: CTRL: n=16, DIDRY: n=21, and DRY: n=19) were analyzed by HPLC, using a size-exclusion column with an eluent of 0.5 M sodium phosphate buffer. The patients were primarily grouped according to the results of the basic secretory test (BST) in combination with subjective symptoms such as burning, foreign body sensations, tearing, and "dryness" of the eyes. Patients with BST valuesor = 10 mm/5 min plus two subjective symptoms…
Stability of Ascorbic Acid in Several Blood Collecting Procedures
2003
Purpose: There is good evidence that ascorbic acid (AA) status influences the onset of post-operative complications in intensive care patients. Light and room temperature cause the spontaneous oxidation of AA. Therefore, the stability of AA during modified sample preparation was investigated. Design: Prospective, single centre study. Methods: The AA plasma concentration was analysed in arterial and venous blood with added ethylene-diamine-tetra-acetic acid (EDTA) from 165 subjects. In addition, EDTA or heparin was added as an anticoagulant in venous blood of 79 subjects. Analyses were carried out using high performance liquid chromatography with ultraviolet detection. Results: In samples of…
Determination of Nuclear Prostatic Androgen Receptors by FPLC (Fast Protein Liquid Chromatography)
1987
The experimental detection of steroid receptors, quantitative as well as qualitative, has been received with wide-spread interest in the research of the various effects of steroid hormones during recent years. The quantitative measurement of cyto- and karyoplasmatic prostatic androgen receptors, carried out through such methods as the Dextran-Coated-Charcoal-Method (DCC) (Snochowsky et al. 1977), the gradient centrifugation method (Mainwaring and Milroy 1975; Menon et al. 1978) or the Hydroxyl-apatite process (Murthy et al. 1984; Pavlik and Coulson 1976), represent unprecise or complicated analytical processes, which are due to technical factors, such as proteolytical degradation, the time …
Assessing alcohol consumption through wastewater-based epidemiology: Spain as a case study
2020
Background In this study, an alternative and complementary method to those approaches currently used to estimate alcohol consumption by the population is described. This method, known as wastewater-based epidemiology (WBE), allows back-calculating the alcohol consumption rate in a given population from the concentrations of a selected biomarker measured in wastewater. Methods Composite (24-h) wastewater samples were collected at the inlet of 17 wastewater treatment plants located in 13 Spanish cities for seven consecutive days in 2018. The sampled area covered 12.8% of the Spanish population. Wastewater samples were analyzed to determine the concentration of ethyl sulfate, the biomarker use…
Use of a three-factor interpretive optimisation strategy in the development of an isocratic chromatographic procedure for the screening of diuretics …
2000
Screening of diuretics in urine is feasible through direct injection of the samples into the chromatographic system and isocratic reversed-phase liquid chromatography (RPLC) with micellar-organic mobile phases of sodium dodecyl sulfate (SDS) and 1-propanol. The surfactant coverage of the chromatographic column makes the addition of organic competing amines less necessary than in conventional aqueous-organic RPLC to achieve well-shaped peaks. Also, the range of elution strengths of micellar mobile phases required to elute mixtures of hydrophobic and hydrophilic diuretics is smaller. This allows the isocratic separation of the diuretics within adequate analysis times. An interpretive methodol…
High-performance liquid chromatographic determination of diuretics in urine by micellar liquid chromatography.
1992
The use of micellar liquid chromatography for the determination of diuretics in urine by direct injection of the sample into the chromatographic system is discussed. The retention of the urine matrix at the beginning of the chromatograms was observed for different sodium dodecyl sulphate (SDS) mobile phases. The eluent strengths of a hybrid SDS-methanol micellar mobile phase for several diuretics were compared and related to the stationary phase/water partition coefficient with a purely micellar mobile phase. The urine band was appreciably narrower with a mobile phase of 0.05 M SDS-5% methanol (v/v) at 50 degrees C (pH 6.9). With this mobile phase the determination of bendroflumethiazide an…
Rearrangement of N-(3-pyridyl)nitramine
2009
AbstractContrary to other N-(pyridyl)nitramines, the title compound cannot be rearranged to 3-amino-2-nitropyridine or other isomers. Hypothetical products of its transformation under influence of concentrated sulphuric acid, viz. 3-hydroxypyridine, 3,3′-azoxypyridine and 3,3′-azopyridine, were obtained from 3-nitro- and 3-aminopyridine in oxidation and reduction reactions. N-(3-Pyridyl)nitramine was prepared and rearranged in concentrated sulphuric acid. 3-Hydroxypyridine and 3,3′-azoxypyridine were isolated from the reaction mixture, other products were identified by the HPLC and GCMS methods. The results indicate that N-(3-pyridyl)hydroxylamine is an intermediate formed from N-(3-pyridyl…