Search results for "liquid chromatography"
showing 10 items of 942 documents
Single hollow fiber SLM extraction of polyamines followed by tosyl chloride derivatization and HPLC determination
2007
Determination of polyamines in biological fluids possesses medical diagnostic relevance. Despite the vast panel of analytical methods developed for polyamines they are not applied in routine clinical usage, mainly due to the time and labor consuming sample preparation step and complicated derivatization procedures. Thus, new simpler methods are needed. This paper describes a single hollow fiber SLM extraction method of polyamines followed by simple pre-column derivatization with tosyl chloride and HPLC-UV analysis. The influence of different parameters such as the extraction time, organic phase composition, acceptor pH, donor pH, acceptor volume, donor volume and stirring speed on the trans…
Risk assessment of exposure to organic chemicals in children and mothers using human biomonitoring
2022
Today, global chemical manufacturing is increasing each year, making environmental pollution and exposure to chemicals a serious public health problem linked to the development of many non-genetic diseases. Approximately, 70 % of chemicals consumed in Europe in 2019 were hazardous for human health. These harmful substances can enter to the food chain and remain in the environment, making humans exposed to them mainly by ingestion, inhalation or dermal exposure. Consequently, exposure to chemicals should be continuously monitored for assuring health protection of citizens by two ways: i) studying their presence in environmental compartments, such as water, food, soil or air, by environmental…
[35] Determination of oxidized glutathione in blood: High-performance liquid chromatography
1994
Publisher Summary The measurement of glutathione status is important in determining oxidative stress in tissues and biological fluids. The ratio of reduced to oxidized glutathione (GSH/GSSG) is a good indicator of the oxidative stress that may occur under physiological and pathological conditions. Changes in GSSG levels have been considered as intracellular signals able to modulate enzyme activity. Thus, it is important to have accurate methods to determine GSSG in biological fluids and in cells. In many cases, it is possible to use tissues, such as liver, muscle, or brain to determine GSH/GSSG. However, especially in human studies, samples from these tissues are not readily available; the …
Trace Analysis of Plutonium and Technetium by Resonance Ionization Mass Spectrometry Using an Atomic Beam and a Laser Ion Source
1990
A method for low level detection of plutonium and technetium is described with a detection limit of less than 107 atoms. Plutonium is a very toxic element due to its radioactive decay as well as its chemical behaviour. It was released to the environment in large amounts during the fifties and sixties of his century, principally by nuclear-weapon tests and some accidents. As a result about 0.4 − 4 mBq per gram 239Pu(T1/2 = 24390 y), corresponding to 4 × 108 − 4 × 109 atoms, can be found in the Northern Hemisphere in soil samples.
Occurrence of pharmaceuticals in municipal wastewater treatment plants and receiving surface waters in Central and Southern Finland
2016
The presence of five selected pharmaceuticals, four anti-inflammatory drugs, diclofenac, ibuprofen, ketoprofen, naproxen, and an antiepileptic drug carbamazepine, was determined at four municipal wastewater treatment plants (WWTPs) and in the receiving waterway near the city of Jyväskylä, in central Finland and also in the River Vantaa. First, an analytical method was developed including a pretreatment and purification followed by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) in the multiple reaction monitoring mode. The studied pharmaceuticals were detected from influents and effluents of four municipal WWTPs and from surface water of eight locations along the water …
N-Cinnamoyltetraketide Derivatives from the Leaves of Toussaintia orientalis
2015
Seven N-cinnamoyltetraketides (1−7), including the new Ztoussaintine E (2), toussaintine F (6), and toussaintine G (7), were isolated from the methanol extract of the leaves of Toussaintia orientalis using column chromatography and HPLC. The configurations of E-toussaintine E (1) and toussaintines A (3) and D (5) are revised based on single-crystal X-ray diffraction data from racemic crystals. Both the crude methanol extract and the isolated constituents exhibit antimycobacterial activities (MIC 83.3−107.7 μM) against the H37Rv strain of Mycobacterium tuberculosis. Compounds 1, 3, 4, and 5 are cytotoxic (ED50 15.3−105.7 μM) against the MDA-MB-231 triple negative aggressive breast cancer cel…
Temperature effects explain continental scale distribution of cyanobacterial toxins
2018
Insight into how environmental change determines the production and distribution of cyanobacterial toxins is necessary for risk assessment. Management guidelines currently focus on hepatotoxins (microcystins). Increasing attention is given to other classes, such as neurotoxins (e.g., anatoxin-a) and cytotoxins (e.g., cylindrospermopsin) due to their potency. Most studies examine the relationship between individual toxin variants and environmental factors, such as nutrients, temperature and light. In summer 2015, we collected samples across Europe to investigate the effect of nutrient and temperature gradients on the variability of toxin production at a continental scale. Direct and indirect…
Availability of extractives from various Norway spruce (Picea abies) stumps assortments
2022
Stumps and knotwood of Norway spruce (Picea abies) are valuable sources of wood extractives. Although lignans from knotwood have already been utilized in value-added products, the behavior and valorization of stump-derived extractives are less studied. In this study, the composition of lipophilic and hydrophilic extractives, particularly lignans, from various spruce stump samples (stump bottom, stump heart, and crushed stump samples) stored outside were studied. Lipophilic and hydrophilic extracts were separated with an accelerated solvent extraction (ASE) apparatus using n-hexane and hot water, respectively. The detailed extractives content of samples was then determined by gas chromatogra…
A multiresidue analytical method for trace level determination of antibiotics and antiretroviral drugs in wastewater and surface water using SPE-LC-M…
2016
An analytical method for simultaneous determination of seven commonly used antibiotics and three antiretrovirals in surface water and urban wastewater at the ng L−1 level has been developed. The method involves concentration and clean-up by solid phase extraction (SPE) followed by identification and quantification by liquid chromatography tandem mass spectrometry (LC-ESI-MS/MS). The use of matrix-matched calibration curves constructed by spiking surface water was evaluated for quantification and compared with the internal standard method using isotopically labelled compounds. The method gave absolute recoveries of 41–116% with most of the compounds having recoveries >50%. The LOQs ranged fr…
Triacylglycerol Analysis in Human Milk and Other Mammalian Species: Small-Scale Sample Preparation, Characterization, and Statistical Classification …
2015
In this work, a method for the separation of triacylglycerols (TAGs) present in human milk and from other mammalian species by reversed-phase high-performance liquid chromatography using a core–shell particle packed column with UV and evaporative light-scattering detectors is described. Under optimal conditions, a mobile phase containing acetonitrile/n-pentanol at 10 °C gave an excellent resolution among more than 50 TAG peaks. A small-scale method for fat extraction in these milks (particularly of interest for human milk samples) using minimal amounts of sample and reagents was also developed. The proposed extraction protocol and the traditional method were compared, giving similar results…