Search results for "PREP"
showing 10 items of 1334 documents
Ar jauniem bioloģiskiem preparātiem apstrādātās augsnes molekulāri bioloģiskais raksturojums
2017
Šī pētījuma mērķis bija noskaidrot divu jaunu bioloģisko preparātu ietekmi uz augsnes mikroorganismu ģenētiskā materiāla koncentrācijām un sugu sastāvu. Pētījums tika sadalīts divos neatkarīgos eksperimentos. Pirmajā eksperimentā pētāmie augsnes parauglaukumi tika apstrādāti ar mikroorganismus saturošu kūdras preparātu, bet otrajā – rapša salmiem un mikroorganismiem ar celulolītisko aktivitāti. Parauglaukumos audzēja miežus un rapsi. Pētījumā tika pielietotas gan klasiskās mikrobioloģijas metodes, lai identificētu augsnes mikrobiotas raksturīgākos pārstāvjus, gan molekulārās – PCR, qPCR, ARDRA, lai noteiktu augsnes mikroorganismu ģenētiskā materiāla koncentrācijas. Tika veikta klasteranalīz…
Safety and immunomodulatory effects of three probiotic strains isolated from the feces of breast-fed infants in healthy adults: SETOPROB study.
2013
We previously described the isolation and characterization of three probiotic strains from the feces of exclusively breast-fed newborn infants: Lactobacillus paracasei CNCM I-4034, Bifidobacterium breve CNCM I-4035 and Lactobacillus rhamnosus CNCM I-4036. These strains were shown to adhere to intestinal mucus in vitro, to be sensitive to antibiotics and to resist biliary salts and low pH. In the present study, a multicenter, randomized, double-blind, placebo-controlled trial with 100 healthy volunteers in three Spanish cities was carried out to evaluate the tolerance, safety, gut colonization and immunomodulatory effects of these three probiotics. Volunteers underwent a 15-day washout perio…
A comparative study on sample preparation procedures for supplementary foods by ICP-OES: Green chemistry considerations
2015
An inductively coupled plasma optical emission (ICP-OES) method was developed for the simultaneous determination of major, minor and trace elements in food. Preliminary studies focused on selecting suitable operational conditions in order to provide the highest sensitivity and to maximize the number of analytes to be determined without spectral or matrix interference. Ruthenium and rhenium were evaluated as internal standards and samples were analyzed at different dilution levels. Furthermore, a comparative study was carried out by using three sample digestion methods, microwave-assisted digestion with HNO3/H2O2, dry ashing and dry ashing with Mg(NO3)2/MgO as an ashing aid. Adequate precisi…
Development of microextraction techniques in combination with GC-MS/MS for the determination of mycotoxins and metabolites in human urine.
2017
Simple and highly efficient sample preparation procedures, namely, dispersive liquid–liquid microextraction and salting-out liquid–liquid extraction for the analysis of ten Fusarium mycotoxins and metabolites in human urine were compared. Various parameters affecting extraction efficiency were carefully evaluated. Under optimal extraction conditions, salting-out liquid–liquid extraction showed a better accuracy (84–96%) and precision (<14%) than dispersive liquid–liquid microextraction. Hence, a multibiomarker method based on salting-out liquid–liquid extraction followed by gas chromatography with tandem mass spectrometry was proposed. Satisfactory results in terms of validation were achiev…
Development of a GC–MS/MS strategy to determine 15 mycotoxins and metabolites in human urine
2014
The widespread mycotoxins contamination of food commodities has made the monitoring of their levels essential. To overcome the disadvantages of the indirect approach by food analysis, detection of mycotoxin as biomarkers in urine provides a useful and specific data for exposure assessment to these food contaminants. In this work, a sensitive, rapid and accurate method based on gas chromatography-tandem mass spectrometry procedure to determine 15 mycotoxins and metabolites in human urine was optimized and validated taking into consideration the guidelines specified in Commission Decision 2002/657/EC and 401/2006/EC. A salting-out assisted acetonitrile-based extraction was used for sample pre…
Use of the modified quick easy cheap effective rugged and safe sample preparation approach for the simultaneous analysis of type A- and B-trichothece…
2010
A suitable extraction and purification method for the simultaneous liquid chromatography-mass spectrometry (LC-MS) determination of five mycotoxins, three type A, diacetoxyscirpenol (DAS), T-2 toxin (T-2) and HT-2 toxin (HT-2), and two type B-trichothecenes, deoxynivalenol (DON) and nivalenol (NIV), has been optimised using a modified "Quick Easy Cheap Effective Rugged and Safe" (QuEChERS) method. Different solvents were studied in the extraction procedure to obtain better recoveries, which ranged from 86 to 108%, using a 85/15 (v/v) mixture of methanol/acetonitrile. The values obtained for recovery, repeatability and reproducibility of the optimized method are in agreement with Commission …
A chromatographic objective function to characterise chromatograms with unknown compounds or without standards available
2015
Abstract Getting useful chemical information from samples containing many compounds is still a challenge to analysts in liquid chromatography. The highest complexity corresponds to samples for which there is no prior knowledge about their chemical composition. Computer-based methodologies are currently considered as the most efficient tools to optimise the chromatographic resolution, and further finding the optimal separation conditions. However, most chromatographic objective functions (COFs) described in the literature to measure the resolution are based on mathematical models fitted with the information obtained from standards, and cannot be applied to samples with unknown compounds. In …
Sample Preparation Improvement in Polycyclic Aromatic Hydrocarbons Determination in Olive Oils by Gel Permeation Chromatography and Liquid Chromatogr…
2005
Abstract The determination of 15 polycyclic aromatic hydrocarbons (PAHs) in olive oil samples has been improved in order to obtain a fast methodology with a low limit of detection through the combination of liquid–liquid extraction with acetonitrile and preparative gel permeation chromatography (GPC) prior to the injection of purified extracts into a C18 column. Acetonitrile–water was used as the mobile phase with a gradient from 50 to 95%, w/w, acetonitrile in 30 min. The oven temperature was maintained at 15°C, and fluorometric detection was made at a fixed excitation wavelength of 264 nm and variable, optimal emission wavelength for each analyte ranging from 352 nm for 11-H-benzo(b)fluor…
Automatic detection and classification of retinal vascular landmarks
2014
The main contribution of this paper is introducing a method to distinguish between different landmarks of the retina: bifurcations and crossings. The methodology may help in differentiating between arteries and veins and is useful in identifying diseases and other special pathologies, too. The method does not need any special skills, thus it can be assimilated to an automatic way for pinpointing landmarks; moreover it gives good responses for very small vessels. A skeletonized representation, taken out from the segmented binary image (obtained through a preprocessing step), is used to identify pixels with three or more neighbors. Then, the junction points are classified into bifurcations or…
Development of a sensitive method for the determination of acrylamide in coffee using high-performance liquid chromatography coupled to a hybrid quad…
2015
The emerging trend towards high-resolution mass spectrometry (MS) alternatives was evaluated by the application of Orbitrap MS for the determination of acrylamide in coffee samples. The high resolving power of the Orbitrap MS provided the high selectivity and sensitivity that enabled quantitative analysis of acrylamide in complex matrices, such as coffee. Several sample preparation methods and scanning modes of the MS (full MS, t-SIM, t-MS2) were assessed in order to optimise parameters of the analytical method. The final procedure involved the extraction of acrylamide with acetonitrile, solid-phase extraction with dispersive primary secondary amine (PSA) and amino columns, and the detectio…