Search results for "ample"

The Role of the Liquid Chromatography-Mass Spectrometry in Pesticide Residue Determination in Food

2008

The use of liquid chromatography (LC) in pesticide residue determination was usually limited to groups of compounds or single compounds for which no suitable gas chromatographic (GC) conditions were available. However, recent developments have significantly enlarged the LC scope in this field of analysis. One of the most important advances was the on-line coupling of efficient LC separation with mass spectrometry detectors (LC-MS and LC-MS/MS) that makes this technique an excellent method for the determination of pesticides and their transformation products in complex matrices such as food. This review considers the application of LC-MS/MS in this field. Emphasis is placed on the tandem MS …

Last trends in pesticide residue determination by liquid chromatography–mass spectrometry

2014

Liquid chromatography–mass spectrometry (LC–MS) is as an excellent analytical tool in the determination of pesticides. Multiresidue analysis of these compounds at trace levels is one of the oldest analytical schemes within environmental and food safety. However, the issue of “pesticide residue determination” is still a hot topic for the analytical community. This review discusses current approaches and recent advances in using LC–MS for pesticide identification and quantification. We outline how MS has influenced the sample preparation process. We critically assess and compare various mass spectrometers, highlighting their strengths and limitations. We, then, review the main applications of…

Infrared biospectroscopy for a fast qualitative evaluation of sample preparation in metabolomics.

2014

Liquid chromatography-mass spectrometry (LC-MS) has been increasingly used in biomedicine to study the dynamic metabolomic responses of biological systems under different physiological or pathological conditions. To obtain an integrated snapshot of the system, metabolomic methods in biomedicine typically analyze biofluids (e.g. plasma) that require clean-up before being injected into LC-MS systems. However, high resolution LC-MS is costly in terms of resources required for sample and data analysis and care must be taken to prevent chemical (e.g. ion suppression) or statistical artifacts. Because of that, the effect of sample preparation on the metabolomic profile during metabolomic method d…

Effect of solvents on the selectivity of terbutylazine imprinted polymer sorbents used in solid-phase extraction

2002

A solid-phase extraction sample preparation method using a molecularly imprinted polymer (MIP) selective for the triazine type pesticide terbutylazine has been developed. The method involves preconcentration from large volumes of water samples on a C18 disk coupled to selective clean-up on the MIP. The method has been optimised by studying the recovery and retention of terbutylazine and some other structurally related triazine derivates as a function of the selective washing solvent used. The effect of the water content of the selective washing solvent was also investigated on the recovery of the MIP. River water samples were analysed with the coupled technique, and efficient clean-up of th…

Determination of water-soluble vitamins in energy and sport drinks by micellar electrokinetic capillary chromatography

2016

Abstract A method for the determination of water-soluble vitamins in several energy and sport drinks by micellar electrokinetic chromatography (MEKC) has been developed in this work. The separation of vitamins was studied in terms of background electrolyte composition (borate content, pH, surfactant type and content) and in other MEKC parameters. A study of the possible compounds found in the vitamin-enriched drinks that could interfere in vitamin determination was also performed, and a modified procedure with enhanced resolution was developed. The proposed method was successfully applied to the analysis of water-soluble vitamins in a variety of energy and sport drinks and also in fruit nec…

Solubility of some pesticides in supercritical CO2

1988

The solubility limits of some pesticides (Linuron, Methoxychlor, Diclofopmethyl, Diclofop and 2,4-D) and of 3,4-dichloroaniline have been determined in supercritical CO2 at 200 bar and 40° C, using the Milton Roy sample preparation accessory SPATM. Depending on the polarity and vapour pressure of the investigated compounds, the solubility was found to be between 0.3 and 12 gl−1.

Supercritical Fluid Extraction and Supercritical Fluid Chromatography of Vitamin E in Pharmaceutical Preparations

1999

Peptides analysis in blood plasma using on-line system of supported liquid membrane and high-performance liquid chromatography

2005

The potential of using supported liquid membrane (SLM) technique, combined with reversed-phase high-performance liquid chromatography (RP-HPLC) has been investigated for the determination of peptides in human blood plasma. The peptides studied were (DL)Leu(DL)Phe, MetLeuPhe, GlyLeuTyr and ValGluProlleProTyr. The carrier (Aliquat 336) was incorporated in membrane phase in order to facilitate the transport of investigated peptides. After extraction, the analyte-enriched acceptor phase was directly injected into an HPLC system for analysis. With SLM, high selectivity and efficiency were achieved for extraction of peptides in aqueous solutions. Lower extraction efficiency was obtained in plasma…

Botanical Origin Authentication of Polish Phacelia Honey Using the Combination of Volatile Fraction Profiling by HS-SPME and Lipophilic Fraction Prof…

2019

Eleven samples of Polish Phacelia tanacetifolia Benth., three Brassica napus and one Salix spp. honeys were characterized by melissopalynology and analysis of the compositions of their volatile fractions. Headspace solid-phase microextraction coupled with gas chromatography mass spectrometry (HS-SPME/GC–MS) using PDMS/CAR/DVB fiber was used for the isolation of low-molecular weight compounds which create a volatile fraction. To differentiate and indicate the most representative unifloral samples, chemometric techniques such as principal component analysis (PCA) and hierarchical-tree clustering (HTC) were applied to the dataset of the chromatographic fingerprints. Based on the obtained resul…

Erfassung niedriger Legionellen-Konzentrationen in Badebeckenwasser

2001

The Legionella proof is necessary in pool water according to DIN 19 643 in case of possible aerosol formation. In lab tests it was proven that the direct spatulation of 1 ml water offers high-grade proof with high correlation of the determined concentration to the actual germ content. With very small germ concentrations, however, preceding filtration of larger sample volumes is necessary. During the investigation of routine samples a Legionella proof was possible thereby in individual cases, whereas direct spatulation remained negative.