RÉSUMÉ
The exocellular polysaccharide S-7, a heteropolysaccharide from Azotobacter indicus var. myxogenes has been studied using methylation analysis, Smith degradation, partial acid hydrolysis, NMR spectroscopy and mass spectrometry as the principal methods. It is concluded that the repeating unit has the following structure: [structure: see text] The absolute configuration of the deoxyhexuronic acid was deduced from 1H NMR chemical shifts and is most likely D. Approximately two O-acetyl groups per repeating unit are present, one of which is presumably on the Rha residue. The structure bears great resemblance to another polysaccharide, recently studied, produced by Sphingomonas paucimobilis I-886.
Sujet(s)
Acides hexuroniques/analyse , Oses/analyse , Polyosides bactériens/composition chimique , Azotobacter/composition chimique , Conformation des glucides , Séquence glucidique , Hydrolyse , Spectroscopie par résonance magnétique , Spectrométrie de masse , Méthylation , Données de séquences moléculaires , Structure moléculaireRÉSUMÉ
A method for the determination of aflatoxicol in urine has been developed. The urine samples were cleaned up by an automated procedure using immunoaffinity columns before analysis by high-performance liquid chromatography and fluorescence detection. Post-column derivatization with bromine allowed the simultaneous determination of aflatoxicol and aflatoxins B1, B2, G1, G2, M1, and Q1. Average recovery of aflatoxicol was 99% in the range 4-40 pg ml-1 of spiked urine samples. The relative standard deviations were all between 1% and 3%. The limit of detection was 1 pg ml-1 urine. Authentic samples from exposed feed-factory workers were analysed, but aflatoxin levels were found to be below the detection limit.
Sujet(s)
Aflatoxines/urine , Chromatographie d'affinité/méthodes , Chromatographie en phase liquide à haute performance , Industrie alimentaire , Humains , Exposition professionnelle , Spectrométrie de fluorescenceRÉSUMÉ
A method for the determination of aflatoxins B1, B2, G1, G2, M1 and Q1 in human urine has been developed. The 10-ml urine samples were automatically cleaned up on immunoaffinity columns and analysed by high-performance liquid chromatography (HPLC), including post-column derivatization with bromine and fluorescence detection. Average aflatoxin recoveries were: B1 103%, B2 106%, G1 98% and G2 96% in the range 6.8-73 pg/ml of urine and M1 103% and Q1 100% in the range 18-97 pg/ml of urine. The relative standard deviations were all between 1% and 21%. The determination limits of aflatoxins in urine were 6.8 pg/ml for B1, B2, G1 and G2 and 18 pg/ml for M1 and Q1.
Sujet(s)
Aflatoxines/urine , Cancérogènes/analyse , Chromatographie en phase liquide à haute performance/méthodes , Techniques immunologiques , Aflatoxine B1/urine , Aflatoxine M1/urine , Chromatographie en phase liquide à haute performance/statistiques et données numériques , Humains , Reproductibilité des résultatsRÉSUMÉ
A liquid chromatography/electrospray ionization tandem mass spectrometry method is described for the determination of aflatoxins B1, B2, G1 and G2. Samples of naturally contaminated airborne dust and spiked urine were cleaned up on immunoaffinity columns and analysed by liquid chromatography using either mass spectrometry detection or post-column derivatization with bromine and fluorescence detection. With tandem mass spectrometry, detection limits (S/N = 3) calculated as amount ejected on column were: aflatoxin B1 4 pg, B2 4 pg, G1 5 pg, and G2 10 pg.
Sujet(s)
Aflatoxines/analyse , Poussière/analyse , Aflatoxines/urine , Chromatographie en phase liquide , Humains , Indicateurs et réactifs , Spectrométrie de masse , Spectrométrie de fluorescenceRÉSUMÉ
A liquid chromatographic system with an automated clean-up procedure for aflatoxin Q1 in human urine is described. The samples were cleaned up by using immunoaffinity columns originally designed for aflatoxin M1. The chromatographic system was a C18 column with an acidic mobile phase of acetonitrile-water containing potassium bromide. Fluorescence detection (365/440 nm) of aflatoxin Q1 was enhanced by addition of bromine, using post-column derivatization, which was studied by factorial designs. Average recovery of aflatoxin Q1 in spiked 10-ml urine samples was 88% (R.S.D. = 6.4%) at a level of 50 pg/ml. The determination limit was 49.5 pg/ml urine.
Sujet(s)
Aflatoxines/sang , Aflatoxines/urine , Aflatoxine M1/immunologie , Analyse automatique , Chromatographie d'affinité , Chromatographie en phase liquide à haute performance , Réactions croisées , Humains , Dosage immunologique , Normes de référence , Spectrométrie de fluorescenceRÉSUMÉ
An automated extraction and clean-up procedure was developed for the determination of aflatoxins in human urine at the 50 pg/ml level. Aflatoxins B1, B2, G1 and G2 are captured on C2 extraction columns and simultaneously cleaned up with the aid of a robotic system. The processed samples are analysed by reversed-phase high-performance liquid chromatography. Fluorescence detection was enhanced for aflatoxins B1 and G1 using factorial design optimization of the post-column reactor. Silylation of the glass vials used in the robotic system was of the utmost importance. With non-silylated glass vials, up to 75% of the analytes were lost. Average aflatoxin recoveries were B1 95%, B2 90%, G1 93% and G2 89%.
