Search results for "Sample preparation"
showing 10 items of 343 documents
Analysis of Trace Pharmaceuticals and Related Compounds in Municipal Wastewaters by Preconcentration, Chromatography, Derivatization, and Separation …
2014
A significant portion of pharmaceuticals and other organic chemicals consumed by people and animals are released into municipal wastewater treatment plants. Most of them are degraded during the wastewater treatment processes, but some of them degrade only partially and may be widely transported and dispersed into the aquatic environment. This is why efficient and fast analytical methods are needed for detection of organic compounds in wastewaters at trace levels. Because wastewaters often consist of complex matrices and high-molecular mass materials, e.g., lignocellulosic biomass, which may bring challenges to the sample preparation procedures, efficient pre-concentration methods such as so…
Fractionation of mercury in sediments during draining of Augusta (Italy) coastal area by modified Tessier method
2013
Abstract A modified Tessier method was applied to sediments dredged from Augusta (Italy) coastal area with the purpose of establishing the amount and the forms in which mercury is present in the different sediment fractions. The mercury fractionation was made by measuring the concentration of the metal ion on the solutions and directly on the sediment fractions obtained by sequential extraction. The measurements on the solutions as well as that on the solid fractions were carried out by using a Direct Mercury Analyser, DMA 80. This new instrument does not require sample preparation, and gives results comparable to those obtained with CV-AAS and ICP-MS and few minutes are necessary for each …
Derivatization of ephedrine with o-phthaldialdehyde for liquid chromatography after treatment with sodium hypochlorite.
2000
The usefulness of the reaction with NaClO followed by derivatization with o-phthaldialdehyde (OPA) and N-acetyl-L-cysteine (NAC) has been investigated for the chromatographic analysis of ephedrine. The influence of parameters affecting the two-stage reaction has been evaluated, including concentration of NaClO, time of reaction, temperature and pH. On the basis of these studies, conditions for the pre-column and (automated) post-column determination of ephedrine are presented. The described conditions have been applied to the measurement of ephedrine in the concentration intervals 0.2-20.0 microg/ml and 2.0-50.0 microg/ml for the pre-column and post-column methods, respectively. The possibi…
Micellar electrokinetic chromatography of polyamines and monoacetylpolyamines
2001
A selective procedure for qualitative and quantitative analysis of ten polyamines by micellar electrokinetic chromatography (MEKC) was developed. Benzoylated polyamines and acetylpolyamines in micellar phase of SDS (10 mM) were separated at 25 degrees C by 20 mM borate buffer pH 8.5, containing 8% ethanol, with an applied voltage of 25 kV (5 microA) and then detected at 198 nm. The experimental factors and operational parameters were optimized by performing analysis at different surfactant concentrations, pH, voltage and temperature with and without ethanol. The repeatibility of migration times and peak heights is a peculiarity of the method here described.
Exopeptidase digestion in combination with field desorption mass spectrometry for amino acid sequence determination
1982
Numerous studies have been devoted in the last years to the development of mass spectrometric methods for the sequence determination of peptides [ 1,2]. Most advanced among this work has been so far the rigorous chemical derivatization of oligopeptides to achieve sufficient volatility for the application of conventional (electron impact, EI) mass spectrometry [2-41. For example, the analysis by gas chromatography-mass spectrometry (GC-MS) of mixtures of oligopeptide fragments derivatized after chemical or enzymatic hydrolysis of polypeptides has been successfully used for sequence determinations [2,5]. Major limitations of this approach are that only small peptide derivatives are amenable t…
Automation of the determination of hydrogen peroxide, dichromate, formaldehyde and bicarbonate in milk by flow injection analysis
1992
Automatic flow injection methods for the determination of hydrogen peroxide, dichromate, formaldehyde and bicarbonate in dairy products are proposed. They are based on reaction with vanadium pentoxide, diphenyl-carbazide, fuchsine-sulphur dioxide and alizarin, respectively. Sample pre-treatment (paper and membrane filtration, dialysis) is widely discussed for on-line incorporation. The usefulness of these methods was tested by applying them to different commercial samples, satisfactory results being obtained in all instances.
FIA-fluorimetric determination of adrenaline by oxidation with a solid-phase reactor of manganese dioxide incorporated in polyester resin beads
1995
Abstract The FIA-spectrofluorimetric determination of adrenaline was carried out by reaction of the drug with manganese dioxide entrapped in a polymeric material in a solid-phase reactor; the oxidized drug was monitored fluorimetrically at 540 nm (Ioxg. 330.0 nm). The calibration graph for adrenaline was linear over the range 0.5 - 20 μg ml−1 with a relative standard deviation of 2.0% (at 5 ug ml−1) and the sample throughput of 65 h−1. The influence of foreign compounds was studied and the method was applied to the determination of adrenaline content in a pharmaceutical formulation . ∗Present address: Institut of Chemistry, Warsawa University, Bialystok Branch, Bialystok, Poland.
Determination of essential metals in complete diet feed by flow injection and flame atomic absorption spectrometry
2002
A prior study of different sample pre-treatments for the determination of metallic elements in complete diet feeds was performed in order to choose the most suitable for these samples. The studied pre-treatment were: acid extraction (lixiviation), wet digestion (on microwave oven) and dry ashing mineralization (calcination). Lixiviation (acid extraction) with hydrochloric acid was selected due to its accuracy, fast and simple pre-treatment procedure. Due of the different levels of concentration of the metallic elements in the samples, the same manifold was used but with small variations. Copper (with on-line pre-concentration by chelating Chelex-100 resin), calcium (with on-line dilution) a…
Applications of Super Resolution Expansion Microscopy in Yeast
2021
Super-resolution microscopy includes multiple techniques in optical microscopy that enable sub-diffraction resolution fluorescence imaging of cellular structures. Expansion microscopy (EXM) is a method of physical expansion to obtain super-resolution images of a biological sample on conventional microscopy. We present images of yeast organelles, applying the combination of super-resolution and ExM techniques. When preparing pre-expanded samples, conventional methods lead to breakage of dividing yeast cells and difficulties in studying division-related proteins. Here, we describe an improved sample preparation technique that avoids such damage. ExM in combination with Airyscan and structured…
Analytical procedures for short chain chlorinated paraffins determination - How to make them greener?
2019
Abstract The aim of the following paper was to gather current scientific information about the analytical protocols dedicated to measuring the content level of short-chain chlorinated paraffins (SCCPs) in various types of environmental samples. Moreover, the data about the basic validation parameters of applied procedures for SCCPs determination are listed. The main issue which is highlighted in the paper is the possibility of the application of green analytical chemistry (GAC) principals in the SCCPs measuring process to reduce the environmental impact of the applied methodology. Analytical methods dedicated to SCCPs determination contain a significant number of steps and require advanced …