Search results for "liquid chromatography"
showing 10 items of 942 documents
Stability of Morphine, Morphine-3-Glucuronide, and Morphine-6-Glucuronide in Fresh Blood and Plasma and Postmortem Blood Samples
2001
The present study was designed to determine the stability of morphine and its glucuronides in spiked fresh blood and plasma from live individuals as well as in four authentic postmortem blood specimens for a time interval of up to six months. The samples were stored in glass vials at -20 degrees C, 4 degrees C, and 20 degrees C. Additionally, spiked samples were exposed to light through window glass and subjected to a forced-degradation study at 40 degrees C. Data were established using solid-phase extraction and high-performance liquid chromatography coupled to atmospheric pressure ionization mass spectrometry for isolation and quantitation, providing a sensitive and specific detection met…
Determination of ketosteroid hormones in meat by liquid chromatography tandem mass spectrometry and derivatization chemistry.
2015
A method for the determination and quantification of ketosteroid hormones in meat by mass spectrometry, based on the derivatization of the carbonyl moiety of steroids by O-methylhydroxylamine, is presented. The quantitative assay is performed by means of multiple-reaction-monitoring (MRM) scan mode and using the corresponding labelled species, obtained by reaction with d 3-methoxylamine, as internal standard. The accuracy of the method was established by evaluating artificially spiked samples, obtaining values in the range 90-110%. Recovery tests were performed on blank matrix samples spiked with non-natural steroids including trenbolone and melengestrol acetate. The latter experiment revea…
Determination of active ingredients in cough-cold preparations by micellar liquid chromatography.
2000
The chromatographic behaviour of some active ingredients in cough-cold pharmaceutical preparations, the antihistamine chlorpheniramine (or the dextro enantiomer dexchlorpheniramine), and the phenethylamines phenylephrine, phenylpropanolamine and pseudoephedrine, has been studied using a C(18) column, micellar mobile phases of sodium dodecyl sulphate (SDS) and pentanol, and with UV detection. All possible combinations of chlorpheniramine/phenethylamine were resolved and determined using a mobile phase of 0.15 M SDS-6% (v/v) pentanol at pH 7, with analysis time below 7 min. Repeatabilities and within laboratory precisions were evaluated at four different drug concentrations in the range 0.5-2…
Advances in surface ion suppression from RILIS: Towards the Time-of-Flight Laser Ion Source (ToF-LIS)
2016
Abstract We present results from the development towards the Time-of-Flight Laser Ion Source (ToF-LIS) aiming for the suppression of isobaric contaminants through fast beam gating. The capability to characterize high resistance ion sources has been successfully demonstrated. A ninefold selectivity gain has been achieved through suppression of surface ionized potassium, while maintaining >90% transmission for laser-ionized gallium using a thin wall graphite ionizer cavity combined with a fast beam gate. Initial results from the investigation of glassy carbon as a potential hot cavity ion source are presented. Power-cycle tests of a newly designed mount for fragile ion source cavities indicat…
Impact of glucuronide interferences on therapeutic drug monitoring of posaconazole by tandem mass spectrometry.
2010
Abstract Background: Posaconazole is a novel antifungal drug for oral application intended especially for therapy of invasive mycoses. Due to variable gastrointestinal absorption, adverse side effects, and suspected drug-drug interactions, therapeutic drug monitoring (TDM) of posaconazole is recommended. Method: A fast ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method for quantification of posaconazole with a run-time <3 min was developed and compared to a LC-MS/MS method and HPLC method with fluorescence detection. Results: During evaluation of UPLC-MS/MS, two earlier eluting peaks were observed in the MRM trace of posaconazole. This was only seen in p…
Simultaneous determination of mycotoxin in commercial coffee
2015
Abstract Mycotoxins are secondary metabolites produced by filamentous fungi that usually contaminate food products. Coffee is a natural product susceptible to mycotoxin contamination. The present study evaluates the presence of nivalenol, deoxynivalenol, T-2 and HT-2 Toxin, diacetoxyscirpenol, aflatoxin B 1 , aflatoxin B 2 , aflatoxin G 1 , aflatoxin G 2 , fumonisin B 1 , fumonisin B 2 , ochratoxin A, zearalenone, enniatin A, enniatin A 1 , enniatin B, enniatin B 1 , and beauvericin in coffee samples, using liquid chromatography tandem mass spectrometry (LC-MS/MS). The results show that zearalenone was not present in any sample. In the positive samples the contents of fumonisins ranged from…
Application of hybrid linear ion trap-high resolution mass spectrometry to the analysis of mycotoxins in beer
2011
This paper reports the application of liquid chromatography electrospray ionization ion trap-orbitrap mass spectrometry for the determination of 18 mycotoxins (aflatoxins, fumonisins, trichothecenes, ochratoxin A, sterogmatocystin, beauvaricin, zearalenone and zearalenol) in beer. The extraction procedure was carried out by solid phase extraction (SPE): SPE columns were conditioned with acetonitrile/methanol and water. Beer was loaded onto the column which was washed with water. In these conditions, the recoveries were more than 65% and the relative standard deviation (RSD) were below 18%. The lowest limits of quantification (LLOQ) ranged from 9 to 155 ng ml(-1). Matrix-matched calibration …
Occurrence of Free and Conjugated Mycotoxins in Aromatic and Medicinal Plants and Dietary Exposure Assessment in the Moroccan Population.
2021
Aromatic and medicinal plants (AMPs), as herbal material, are subjected to contamination by various mycotoxin-producing fungi, either free and conjugated. Such a problem is associated with poor storage practices, and lack of adopting good agricultural practices and good harvesting practices. Nevertheless, AMPs are poorly investigated. The purpose of this study was to investigate the co-occurrence of 15 mycotoxins (four aflatoxins (AFB1, AFB2, AFG1, and AFG2), ochratoxin A (OTA), beauvericin (BEA), four enniatins (ENA, ENA1, ENB, and ENB1), zearalenone (ZEN), alternariol (AOH), tentoxin (TENT), T-2, and HT-2 toxins) in 40 samples of AMPs frequently consumed in Morocco by using liquid chromat…
Influence of different coffee drinks preparations on ochratoxin A content and evaluation of the antioxidant activity and caffeine variations.
2011
Coffee is one of the most frequently consumed beverages in North America and Europe. It is well known that coffee contains caffeine and that coffee beans can be contaminated by Ochratoxin A (OTA). The operating conditions however affect OTA and caffeine extraction from the roasted coffee. OTA content found in the beverages can be greater than that found in the roasted coffee used to prepare it, representing a potential OTA related risk factor for the human health. Moreover the coffee beans and coffee based beverages have an anti oxidant activity. This study investigates the OTA content, the amount of caffeine, and the antioxidant activity in five different preparations: American coffee, Mok…
Determination of ochratoxin A in beer marketed in Spain by liquid chromatography with fluorescence detection using lead hydroxyacetate as a clean-up …
2005
Abstract A new sample treatment for liquid chromatographic analysis of ochratoxin A (OTA) in beer is proposed. Degassed beer is mixed with lead hydroxyacetate, which precipitates some bulk components but does not remove OTA. The precipitate is separated and the acidified liquid is extracted with chloroform. The solvent is evaporated and the residue is dissolved in mobile phase (acetonitrile–water, 40:60, v/v; acidified at pH 3.0 with phosphoric acid) and separated by liquid chromatography using fluorescence detection. The limit of detection was 0.005 ng/ml. The average recovery rate and the average RSD of recovery in the spiking level range 0.01–0.5 ng/ml were 95.5% and about 5%, respective…