Search results for "High-performance liquid chromatography"
showing 9 items of 629 documents
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…
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…
Increasing Yield and Antioxidative Performance of Litchi Pericarp Procyanidins in Baked Food by Ultrasound-Assisted Extraction Coupled with Enzymatic…
2018
Extraction with organic solvents is a traditional method to isolate bioactive compounds, which is energy-wasting and time-consuming. Therefore, enzyme and ultrasound treatments were combined to assist the extraction of oligomeric procyanidins from litchi pericarp (LPOPC), as an innovative approach to replace conventional extraction methods. Under optimum conditions (enzyme concentration 0.12 mg/mL, ultrasonic power 300 W, ultrasonic time 80 min, and liquid/solid ratio 10 mL/g), the yield of LPOPC could be improved up to 13.5%. HPLC analysis indicated that the oligomeric procyanidins (OPC) content of LPOPC from proposed extraction was up to 89.6%, mainly including (&minus
Polyphenols and Pharmacological Screening of a Monarda fistulosa L. dry Extract Based on a Hydrodistilled Residue By-Product
2021
This study aimed to determine the composition and content of polyphenols in the dry extract obtained from the hydrodistilled residue by-product of the wild bergamot (Monarda fistulosa L., Lamiaceae Martinov family) herb (MFDE) and to evaluate its safety and pharmacological properties. The total phenolic content (TPC) in the MFDE was 120.64 mg GAE/g. The high-performance liquid chromatography (HPLC) analysis showed the presence of a plethora of phenolic compounds, including hydroxycinnamic acids and flavone derivatives in the MFDE, with rosmarinic acid and luteolin-7-O-glucoside being the main components. With an IC50 value of 0.285 mg/mL, it was found to be a strong DPPH radical scavenger. …
Assays for detection of fungal hallucinogens such as psilocybin and psilocin
2016
Methods applicable to the detection of hallucinogenic indole compounds, namely psilocybin, psilocin, and related molecules, that have been developed so far for purposes of mycological research, toxicological studies, or forensic investigations are described in this chapter. The most current literature as well as some interesting older publications are cited, providing a historical overview of the subject. Methods of qualitative and quantitative analysis are presented. Additionally, preliminary purification steps and sample treatment before the exact quantitative determination are proposed. The methods described utilized various analytical techniques for the measurement of psilocybin/psiloci…
Determination of glyphosate and its metabolite aminomethylphosphonic acid in fruit juices using supported-liquid membrane preconcentration method wit…
2005
Abstract The application of supported-liquid membrane (SLM) technique for effective extraction of N -(phosphonomethyl)glycine (glyphosate) and its primary metabolite aminomethylphosphonic acid (AMPA) from juices (orange, grapefruit, apple and blackcurrant) in combination with HPLC-UV detection after derivatization with p -toluenesulphonyl chloride (TsCl) is presented. The influence of various parameters such as the composition of acceptor phase, flow-rate, concentration of analytes, on the performance of extraction procedure, was studied. It was shown that by appropriate manipulation of SLM parameters the level of detection could be significantly improved. The influence of SLM conditions on…
Behaviour of Extractives in Norway Spruce (Picea abies) Bark during Pile Storage
2022
The current practices regarding the procurement chain of forest industry sidestreams, such as conifer bark, do not always lead to optimal conditions for preserving individual chemical compounds. This study investigates the standard way of storing bark in large piles in an open area. We mainly focus on the degradation of the most essential hydrophilic and hydrophobic extractives and carbohydrates. First, two large 450 m3 piles of bark from Norway spruce (Picea abies) were formed, one of which was covered with snow. The degradation of the bark extractives was monitored for 24 weeks. Samples were taken from the middle, side and top of the pile. Each sample was extracted at 120 °C with both n-h…
Development of an immunochromatographic assay based on carbon nanoparticles for the determination of the phytoregulator forchlorfenuron
2013
Rapid analytical methods enabling the determination of diverse targets are essential in a number of research areas, from clinical diagnostics to feed and food quality and safety. Herein, the development of a quantitative immunochromatographic assay for the detection of the synthetic phytoregulator forchlorfenuron (CPPU) is described. The competitive lateral flow immunoassay (LFIA) was based on the immobilization onto a nitrocellulose membrane of an ovalbumin-CPPU conjugate (test line) and on the use of an immunodetection ligand consisting of carbon nanoparticles labeled with an anti-CPPU monoclonal antibody through interaction with a secondary antibody. The presence of CPPU in horticultural…