Search results for "Extraction"

Evaluation of a new pooling strategy based on leukocyte count for rapid quantification of allele frequencies.

2007

Abstract Background: Allele frequencies of single-nucleotide polymorphisms (SNPs) can be quantified from DNA pools. The conventional preparation of DNA pools requires DNA isolation and quantification for each blood sample. We hypothesized that pooling of whole blood samples according to their leukocyte count, which determines DNA content, would be as reliable as the conventional pooling method but much less tedious to perform. Methods: We collected 100 whole blood samples and measured the leukocyte count. Samples were frozen until further use. After thawing, pools were generated by combining aliquots containing an equal number of leukocytes. In parallel, DNA was extracted from another aliqu…

LogDet divergence-based metric learning with triplet constraints and its applications.

2014

How to select and weigh features has always been a difficult problem in many image processing and pattern recognition applications. A data-dependent distance measure can address this problem to a certain extent, and therefore an accurate and efficient metric learning becomes necessary. In this paper, we propose a LogDet divergence-based metric learning with triplet constraints (LDMLT) approach, which can learn Mahalanobis distance metric accurately and efficiently. First of all, we demonstrate the good properties of triplet constraints and apply it in LogDet divergence-based metric learning model. Then, to deal with high-dimensional data, we apply a compressed representation method to learn…

Analysis of pesticides in fruits by pressurized liquid extraction and liquid chromatography-ion trap-triple stage mass spectrometry.

2005

A multi-residue method using pressurized liquid extraction (PLE) and liquid chromatography-quadrupole ion trap-triple stage mass spectrometry (LC-IT-MS(3)) has been developed for determining trace levels of pesticides in fruits. The selected pesticides can be distinguished in: benzimidazoles and azoles, organophosphorus, carbamates, neonicotinoids, and acaricides. PLE has been optimized to extract these pesticide residues from oranges and peaches by studying the effect of experimental variables on PLE efficiency. Samples were extracted at high temperature and pressure (75 degrees C and 1500psi) using ethyl acetate as extraction solvent and acidic alumina as drying agent. The recoveries obta…

Production of high value added nutraceuticals in a multi-trophic aquaculture system within a closed circuit marine hatchery (NUTRAQUA)

2022

Analytical methods to determine cocaine contamination of banknotes from around the world

2008

Abstract The presence of cocaine in a significant number of UK pounds (Xxxx), Euros (€) and North American banknotes ($) in general circulation requires appropriate tools to do determinations. This article discusses the-state-of-the-art in the analysis of cocaine on banknotes. We summarize the usual extraction methods of currency samples and compare them, especially with respect to avoiding sample damage. We critically discuss analytical methods, namely gas chromatography (GC) and liquid chromatography (LC), capillary electrophoresis (CE), immunoassay, thermal desorption tandem mass spectrometry (TD-MS2) and ion-mobility spectrometry (IMS). We also review cocaine levels on banknotes around …

Fundamentals and applications of stir bar sorptive dispersive microextraction: A tutorial review

2021

Current trends in sample preparation focus on the miniaturization of the process resulting in what is known as microextraction techniques. Among them stir bar sorptive dispersive microextraction (SBSDME) is one of the most recent techniques. It was presented a few years ago as a hybrid microextraction technique that combines the principles of stir bar sorptive extraction (SBSE) and dispersive solid phase extraction (DSPE). This novel technique introduces, into the sample solution, a bar-shaped magnet coated with a magnetic (nano)material, which is maintained on the surface by magnetism. Once stirring starts, the competitive action between magnetism and rotational force is exploited. At low …

Raw material variability as archaeological tools: Preliminary results from a geochemical study of the basalt vessel workshop at Iron Age Tel Hazor, I…

2016

The discovery of a basalt vessel workshop at Tel Hazor, one of the most important Iron Age sites in the Near East, marks a turning point in our understanding of stone artifact production and distribution during the1st millennium BCE. It offers a rare opportunity to characterize ancient raw material sources, production sites, and study production, trade and distribution systems. The basalt vessel workshop, the only one of its kind in the Levant, produced large quantities of bowl preforms and production waste. To better understand the production and distribution systems behind this specialized production center, in 2011 we initiated a focused geochemical project that concentrated on the produ…

Determination of phenytoin in plasma by molecularly imprinted solid-phase extraction.

2001

Abstract A molecularly imprinted polymer (MIP) using phenytoin as template and methacrylamide as the functional monomer was prepared. The selectivity was measured by comparing capacity factors of phenytoin and other structurally related compounds. The polymer was evaluated as a selective sorbent in molecularly imprinted solid-phase extraction (MISPE). Several washing solvents were tested to study their ability to disrupt the non-specific interactions occurring between the sample and the polymer matrix and the role of water in the recognition process was also investigated. It was shown that the key step of successful sample extraction is the right choice of the washing solvent. Plasma sample…

Trends in Online Intube Solid Phase Microextraction

2017

Recent advances of in-tube solid-phase microextraction

2015

Abstract In-tube solid-phase microextraction (SPME) is ideally suited to developing green extraction by combining miniaturization, automation and reduction of solvent consumption. SPME has been used for the analysis of environmental, biological, and food samples, and numerous works have shown the benefits of using SPME. However, for full development of in-tube SPME, effort is still needed to overcome limitations, such as low extraction efficiency, selectivity and mechanical stability. To achieve these objectives, research on in-tube SPME is mainly focused in two scenarios: (1) the coupling of in-tube SPME with new chromatographic modalities, such as miniaturized liquid chromatography; and, …