Search results for "solution"
showing 10 items of 5638 documents
An Infrared Method, with Reduced Solvent Consumption, for the Determination of Chlorsulfuron in Pesticide Formulations
2003
A simple method has been developed for the determination of Chlorsulfuron in pesticide formulations by Fourier Transform Infrared (FTIR). Samples were diluted with CHCl3− , and the FTIR spectra of the samples and standards were obtained at a nominal resolution of 4 cm− 1 from 4000 to 900 cm− 1 with the accumulation of 25 scans. Chlorsulfuron determination was based on the measurement of peak area values from 1373 to 1363 cm− 1 which were corrected by use of a two points baseline defined from 1401 to 1302 cm− 1. The limit of detection achieved, which was of the order of 6 µg g− 1, was appropriate for the determination of Chlorsulfuron in commercially available formulations. FTIR results were…
Supercritical fluid chromatography in drug analysis: A literature survey
1996
The applications of supercritical fluid chromatography to the analysis of drugs have been carefully revised from the literature compiled in the Analytical Abstracts until March 1994. Easy-to-read tables provide useful information about the state-of-the-art and possibilities offered by SFC in pharmaceutical analysis. The tables comprise extensive data about samples analyzed, pharmaceutical principles determined, solvents used and sample quantity injected, supercritical fluids and modifiers employed, injection system, instrumentation, experimental conditions for chromatographic separations (density, pressure, flow, temperature), characteristics of columns employed (type, support, length, diam…
A rapid HPLC assay for zearalenone in laboratory cultures ofFusarium graminearum
1993
A high pressure liquid chromatographic (HPLC) method to determine zearalenone in corn contaminated withFusarium graminearum is described. After extraction with methanol-water and solvent partition, samples were cleaned up by applying the extract to a disposable silica cartridge and by eluting the toxin with a mixture of hexane/dry ethyl ether (5/5). Separation was achieved by a reverse phase μBondapak C18 column followed by fluorescence detection using an excitation wavelength at 274 nm and an emission wavelength at 440 nm. Detection limit was about 5 ng. Recoveries ranging from 85.37 to 100.97%, in standard solutions range 30–0.5 µg/ml, were found.
Flow injection Fourier transform infrared determination of caffeine in coffee
1999
Abstract A fully automatized procedure has been developed for the Fourier transform infrared (FT-IR) spectroscopic determination of caffeine in coffee samples. The method involves the on-line extraction of caffeine with CHCl3. Samples, weighed inside empty PTFE cartridges of 0.5 cm internal diameter (i.d.) and 1.5 ml volume, were humidified with four drops of 0.25 M NH3. The cartridge was installed in a flow manifold, in which samples were extracted in a closed-flow system with 1 ml CHCl3 during 6 min. Four hundred microliters of the extract were introduced in a microflow cell and absorbance measured as a function of time at 1659 cm−1, with a baseline established between 1900 and 830 cm−1, …
First-order derivative resolution of overlapped PAH peaks with common mass spectra in gas chromatography–mass spectrometry
2007
Abstract First-order derivative of 15 points smoothed chromatograms of mixtures of benzo( b )fluoranthene (BbF) and benzo( k )fluoranthene (BkF) for the m / z 252 ion obtained using two microscans has been proposed as a simple alternative to the resolution of overlapped chromatographic peaks of these two compounds which have identical mass spectra. The procedure provides limits of detection of 12 and 29 ng g −1 for BbF and BkF, respectively and offers the possibility to use the 250 and 248 ions to confirm the identity of these analytes.
Antibody-Capped Mesoporous Nanoscopic Materials: Design of a Probe for the Selective Chromo-Fluorogenic Detection of Finasteride
2012
[EN] The synthesis of capped mesoporous silica nanoparticles (MSN) conjugated with an antibody (AB) as a gatekeeper has been carried out in order to obtain a delivery system able to release an entrapped cargo (dye) in the presence of a target molecule (antigen) to which the conjugated antibody binds selectively. In particular, MSN loaded with rhodamine B and functionalized on the external surface with a suitable derivative of N-(t-butyl)- 3-oxo-(5a,17b)-4-aza-androst-1-ene-17-carboxamide (finasteride) have been prepared (S1). The addition of polyclonal antibodies against finasteride induced capping of the pores due to the interaction with the anchored hapten-like finasteride derivative to g…
Influence of water sample storage protocols in chemiluminescence detection of trace elements.
2002
This paper shows the influence of different sample storage protocols, on the chemiluminescence signal of some metal ions. The storage protocols studied were: acid addition (HCl or HNO(3)) and no reagent addition to filtered and refrigerated (T=4 degrees C) samples. Light emission was produced for the chemiluminescence reaction between luminol and hydrogen peroxide in buffer carbonate conditions (pH 10.8) catalysed by Cr(III), Co(II) and Cu(II). Batch and/or flow modes in different conditions were tested. Fe(II), Fe(III), Ni(II) and Mn(II) did not give chemiluminescence in the studied conditions. A parallel study of sensitivity and selectivity was performed. Then the presence or absence of t…
Simultaneous quantification of the main organic acids and carbohydrates involved in tomato flavour using capillary zone electrophoresis
2002
A capillary zone electrophoresis (CZE) procedure for the simultaneous determination of the major organic acids (oxalate, malate and citrate) and carbohydrates (fructose, glucose and sucrose) in Lycopersicon fruits is reported. Comparison of this method with routine HPLC methods indicates that the CZE method offers several attractive features (speed, resolution, sensitivity and cost) which significantly improve the determination of these compounds. Detection limits were better than 1.6 µg ml−1 for organic acids and from 13 to 24 µg ml−1 for carbohydrates; repeatabilities were better than 2.1% for migration times and between 1.4 and 7.3% for peak areas. The proposed protocol is very useful to…
Automated trace enrichment for screening and/or determination of primary, secondary and tertiary amphetamines in biological samples by liquid chromat…
1999
A rapid and simple liquid chromatographic method for the automated determination of amphetamines in biological fluids was developed. The proposed procedure is based on the injection of 250 microL of sample into a 20 x 2.1 mm id precolumn (packed with a 30 microns Hypersil C18 stationary phase) for enrichment and purification of the analytes. Next, the analytes are transferred to a 5 microns LiChrospher 100 RP18, 125 x 4 mm id analytical column for their separation under reversed-phase conditions. Water was used to eliminate the matrix components from the precolumn and a 0.2 M phosphate buffer (pH 3) containing 2% triethylamine was the mobile phase for the resolution of the amphetamines. The…
Optimization of transmission near infrared spectrometry procedures for quality control of pesticide formulations
2006
The use of different response functions to be optimized in the frame of the use of near infrared spectrometry for quality control of active principles in agrochemical formulations has been evaluated. Both, simple functions, based on parameters like sensitivity, repeatability, accuracy, signal to noise ratio, limit of detection or sample throughput, and a complex function, considering all the aforementioned aspects, were employed in the development of a new method for Iprodione determination in agrochemicals. Optimization strategies were based on the previous screening of the most important instrumental factors like number of cumulated scans, nominal resolution, mirror velocity and zero fill…