Alternaria fungi are widely distributed saprophytes and plant pathogens. As pathogens, Alternaria fungi infect crops and vegetables and cause losses in the fields and during postharvest storage. While farmers suffer from declining yields, consumers are endangered by the formation of secondary metabolites, because some of these exhibit a pronounced toxicological potential. The evaluation of the toxicological capabilities is still ongoing and will contribute to a valid risk assessment. Additionally, data on the incidence and the quantity of Alternaria mycotoxins found in food products is necessary for dietary exposure evaluations. A sensitive LC-MS/MS method for the determination of the Alternaria mycotoxins alternariol (AOH), alternariol monomethylether (AME), tentoxin (TEN), altertoxin I (ATX I), alterperylenol (ALTP), and tenuazonic acid (TA) was developed. AOH, AME, and TA were quantified using stable-isotopically labeled standards. TEN, ATX I, and ALTP were determined using matrix matched calibration. The developed method was validated by using starch and fresh tomato matrix and resulted in limits of detection ranging from 0.05 to 1.25 μg/kg for starch (as a model for cereals) and from 0.01 to 1.36 μg/kg for fresh tomatoes. Limits of quantification were determined between 0.16 and 4.13 μg/kg for starch and between 0.02 and 5.56 μg/kg for tomatoes. Recoveries varied between 83 and 108% for starch and between 95 and 111% for tomatoes. Intra-day precisions were below 4% and inter-day precisions varied from 3 to 8% in both matrices. Various cereal based infant foods, jars containing vegetables and fruits as well as tomato products for infants were analyzed for Alternaria mycotoxin contamination (n = 25). TA was the most frequently determined mycotoxin and was detected in much higher contents than the other toxins. AME and TEN were quantified in many samples, but in low concentrations, whereas AOH, ATX I, and ALTP were determined rarely, among which AOH had higher concentration. Some infant food products were highly contaminated with Alternaria mycotoxins and the consumption of these individual products might pose a risk to the health of infants. However, when the mean or median is considered, no toxicological risk was obvious.
As investigations carried out in an immersion basin of a sauna, with rinsed-off sweat and in indoor and outdoor swimming-baths have shown, from the total of 702 -t 529 mg/urea released per bather there are released 37.06f24.75 mg through the skin into water; hence a urine introduction of 30 ... 35 ml per bather resulting. The urea concentration in the bathing water does not show any correlation with the NHZ-concentration and the COD-Mn. Although urea-degrading bacteria are present with concentrations of up to 1 * 105 colonies/ml, there does not occur any enzymatic decomposition ofurea in the bathing water. Nitrification was not detected in the bathing water, either. The use of urea as a hygienic quality criterion for bathing water is not regarded as necessary: the determination of the NH$-concentration suffices as an indicator of the pollution with faecal matter and the bound effective chlorine. EinfiihrungDer Badegast gilt als Kauptverunreinigungsquelle des Schwimmbeckenwassers (THEUS, GUNKEL und SCHARF 1983). Entscheidenden EinfluB auf die Wasserqualitiit und die MaBnahmen der Wasseraufbereitung hat die Belastung mit Ammoniumionen, Harnstoff und anderen organischen N-Verbindungen, die mit dem Harn und iiber die Haut abgegeben werden. Der Harn muB als Infektionsquelle ( WEBER, LEMB-KE und BERTHOLDT; GERHARDT und MENZER) und als Vorlaufer fur die Haloformbildung ( EICHELSD~RFER, JANDIK und WELL) angesehen werden, Harnstoff und Ammonium gelten als Indikatoren fur fakale Verunreinigungen (THEUS, GUNKEL und SCHARF; WONNE und BIBO) und bilden mit Chlor die gesundheitsbedenklichen Chloramine und Chlorharnstoffe ( ROESKE ; SCHAETZLE ; FLICK).Der Anteil der N-Verbindungen, der mit dem Harn bzw. uber die Haut eingebracht wird, ist ebenso umstritten wie der Zusammenhang des Harnstoffgehaltes mit anderen Untersuchungskriterien. Ziel der Untersuchungen ist deshalb eine differenzierte Aussage iiher die Menge des Harnstoffeintrages zu erhalten, seine Konzentration im Schwimmbeckenwasser zu erniitteln und Ergebnisse uber den enzymatischen Harnstoffabbau im Badewasser zu gewinnen. , LiteraturubersichtDie Ursachen des Harnstoffeintrags, des Harnstoffabbaus durch enzymatische und chemische Hydrolyse sowie die Moglichkeiten der Harnstoffeliminierung werden seit etwa 60 Jahren untersucht. WETTE versuchte, aus der Harnstoffbestimmung jm Badewasser den Urineintrag zu berechnen. Dies gelang nicht, da der Harnstoff 33.
Schimmelpilze der Gattung Alternaria sind weit verbreitet, wachsen auf Nutzpflanzen und hinterlassen giftige Stoffwechselprodukte. Aber anders als Aspergillus‐, Penicillium‐ und Fusarium‐Arten sind sie nur wenig untersucht, und für die Toxine existieren keine Höchstgehalte in Lebens‐ und Futtermitteln. Mit neuen Analysenmethoden könnte sich das ändern.
Zum bioeheinischen Hariistoffabbau in wahiger Losung-Ubersieht Sumiiznry: Urea from natural and anthropogenic soiirc.es is one of the niost interesting nitrogen ronipoiinds in an aqiiat,ic cmvironmrnt . Rcsults of esperimcntd invcst.igat.ionx are prescntcd for the successive biochemical uiea transformat.ion into riitmtrs via nmmoniuru and nitrite species. Kinrtic models based on :I, cornbindtion of MICHAELIS-MENTEN and MONOD equat~ions have been tlerircd which dcscribe reasonably well the course of the enzymat,ic reactions and t'he concent'ration-time profiles of different N oxydation states. Main factors affecting t,he rates of nitrogen met;tbolization are the init,ial concentrat,ion of ureolytic bacteria, the physica.1 stat,c of the nit,rifging microorganisms, and the concentration of toxic orgiinics added to the system under study.
Harnstoffbestimmung im Wasserh'utnmory: For a prolonged time a photometric method of analysis for determining the urea content in waters was tested b y the author. With this method, the urea component of the water sample is hydrolysed into ammonium-ions and photometered by the use of a new indophenol-blue technique (selected methods of water analysis, 1985) with the Spekol a t 546 nm. The ammonium content of the untreated water sample should be taken into account in the esplanatory method of calculation of the urea content. If the state of the water sample is unchanged, urea concentrations of up to about GO mg/l can be determined. The detection limit is a t 0.15 ... 0.20 mgll.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.