Search results for "SAM"
showing 10 items of 7385 documents
Automated Photo-Induced Fluorescence Determination of Flumetsulam
2009
The present article deals with a new procedure for determination of the herbicide flumetsulam. The fluorimetric procedure is performed on the basis of photo-increased fluorimetric emission of the pesticide solution and by means of a multicommutation continuous-flow assembly. The alkaline solution containing the analyte is irradiated online and then directly forced through the fluorimeter flow cell. The analysis of different samples is completely automated, as the analyte separation was performed online by including a separation cartridge in the manifold. When dealing with solid samples (such as soil samples), the automation was completed by adding to the manifold the corresponding device fo…
In-tube solid-phase microextraction-capillary liquid chromatography as a solution for the screening analysis of organophosphorus pesticides in untrea…
2006
This paper describes a method for the selective screening of organophosphorus pesticides in water. In-tube solid-phase microextraction (SPME) in an open capillary column coupled to capillary liquid chromatography (LC) with UV detection has been used to effect preconcentration, separation and detection of the analytes in the same assembly. For in-tube SPME two capillary columns of the same length and different internal diameters and coating thicknesses have been tested and compared, a 30 cm x 0.25 mm I.D., 0.25 micro m thickness coating column, and a 30 cm x 0.1 mm I.D., 0.1 micro m of coating thickness column. In both columns the coating was 95% dimethylpolysiloxane (PDMS)-5% diphenylpolysi…
Validation of a confirmatory method for the determination of macrolides in liver and kidney animal tissues in accordance with the European Union regu…
2006
Abstract This study proposes a simple multiresidue liquid chromatography–diode array detector (LC–DAD) method capable of determining seven macrolide antibiotics in samples of liver and kidney animals at concentrations lower than those allowed by current legislation. Samples were prepared by homogenizing the tissue with EDTA–McIlvaine's buffer and extracted with an Oasis HLB cartridge. The consumption of organic solvent during extraction was minimum. The analytes were detected by LC–DAD and also by liquid chromatography–mass spectrometry with electrospray ionization (LC–(ESI)MS). The method was specific, stable and robust enough for the required purposes. The DAD method was validated in acco…
Green aspects, developments and perspectives of liquid phase microextraction techniques.
2014
Determination of analytes at trace levels in complex samples (e.g. biological or contaminated water or soils) are often required for the environmental assessment and monitoring as well as for scientific research in the field of environmental pollution. A limited number of analytical techniques are sensitive enough for the direct determination of trace components in samples and, because of that, a preliminary step of the analyte isolation/enrichment prior to analysis is required in many cases. In this work the newest trends and innovations in liquid phase microextraction, like: single-drop microextraction (SDME), hollow fiber liquid-phase microextraction (HF-LPME), and dispersive liquid-liqu…
A preliminary study on the stability of benzodiazepines in blood and plasma stored at 4 degrees C.
1997
An approach to determine the stability of benzodiazepines and some of their metabolites (n = 13) by means of a routinely applied gas chromatographic method using electron capture detection was made in this preliminary study. Validation data of the method are given. Spiked blood and plasma samples were stored at 4 degrees C and analysed at selected times up to 240 days. The concentrations of all analytes had decreased to at least 60% of the original levels at the end of the observation period. A clear pattern of breakdown could not be established. The data obtained suggest that results from long-term stored samples should be interpreted cautiously. Further investigations concerning the stabi…
Development and validation of a fast and sensitive chromatographic assay for all-trans-retinol and tocopherols in human serum and plasma using liquid…
2002
A sensitive HPLC assay for all-trans-retinol, alpha-tocopherol, and gamma-tocopherols in human serum and plasma is reported. Sample preparation is performed in one step and involves precipitation of proteins and extraction of lipids with two volumes of an ethanol-chloroform mixture (3:1, v/v) without I.S. addition. After removal of the precipitated protein, 20 microl aliquots of the supernatant (equivalent to 6.7 microl of serum or plasma) were injected into the HPLC system and analyzed using fluorometric detection. RP-HPLC was performed using a C(18) S3 ODS2 column with a methanol-water step gradient (97:3 to 100) at 1.0 ml/min. The quantification limit expressed as nanograms of analyte pe…
Development of a Rapid Method for the Determination of Phenolic Antioxidants in Dark Chocolate Using Ultra Performance Liquid Chromatography Coupled …
2017
Development of a new comprehensive method based on one-step liquid-liquid extraction (LLE) combined with ultra-high-performance liquid chromatography-Orbitrap high resolution mass spectrometry (UHPLC-Orbitrap-HRMS) for the determination of eight phenolic compounds in dark chocolate is demonstrated. The study focuses on the optimization of sample preparation, chromatographic separation and Orbitrap-HRMS detection parameters to adjust selectivity and sensitivity of the method. The LLE mixture of formic acid-water-acetonitrile (2:58:40, v/v) and hexane at the component ratio of 1:1 (v/v) was applied for sample preparation. The inter-day and intra-day precision expressed from the relative stand…
Generalised H-point standard addition method for the isolation of the analyte signal from the sample signal when coelution of unknown compounds occur…
1999
The generalised H-point standard addition method (GHPSAM) is proposed for isolating the analytical signal of an analyte from the signal of an unknown sample. Samples containing two and three coeluting compounds have been analysed. The accuracy of the predictions depends on the shape of the analyte and interferent spectra but not on the degree of chromatographic overlap. This methodology involves the location of linear intervals for the unknown interference spectrum from the spectrum of the sample. Once the linear interval has been found the selection of three wavelengths within the interval will allow the cancellation of the signal of the unknown interferent. The method has been applied to …
One-Pot Analysis: a New Integrated Methodology for Determination of TAG and FA Determination through LC/MS and in-silico Saponification
2017
Vegetable oils differ significantly for their lipid profile and are mainly constituted by triacylglycerols (TAGs). These are esters formed bonding glycerol to three fatty acids (FAs). To the best of our knowledge, FA and TAG profiles in oils and fats are obtained using at least two different experimental techniques. In particular, FA determination requires elaborated procedures for sample preparation and analyte derivatization. In this work, we propose a one-pot analysis able to determine both TAG and FA contents of edible oils, using experimental data obtained from a simple liquid chromatography/mass spectrometry determination of TAGs. This experimental procedure is followed by an in silic…
Real-time polarimetric biosensing using macroporous alumina membranes
2013
We report the first demonstration of real-time biosensing in free standing macroporous alumina membranes. The membranes with their 200 nm diameter pores are ideal candidates for biosensing applications where fast response times for small sample volumes are needed as they allow analytes to flow through the pores close to the bioreceptors immobilized on the pores walls. A bulk refractive index sensitivity of 5.2x10 -6 refractive index units was obtained from signal responses to different concentrations of NaCl solutions flowing through the pores. Finally, after functionalizing the alumina pore surfaces with an epoxysilane and then spotting it with β-Lactoglobulin protein, the interactions bet…