RESUMEN
A treatment with cyanide for the analysis of S-sulfonates in meat and meat derivatives, after a study of the effectiveness of this agent and that of dithiothreitol (DTT), is proposed. Once the protein-bound sulfite has been released, it is determined by HPLC ion exclusion with electrochemical detection. In the assay on the reproducibility of the method, standard deviations were 7.4, 9.2, and 11.4 for mean S-sulfonate values of 69, 107, and 130 microg of SO(2)/g, respectively. Mean recovery was 91.2% for different amounts (56, 111, and 223 microg of SO(2)/g) of S-sulfocysteine added. A study was made of the formation of S-sulfonates in model systems and in meat from different species-chicken and beef-with different fat contents. In the assays with meat, two different levels of sulfite addition were used: 600 and 1200 microg of SO(2)/g. From the assays carried out in model systems with sulfite and cystine it may be concluded that one factor limiting the interaction is the accessibility to disulfide groups. The proportion of S-sulfonates in sulfited meat remains relatively constant and does not seem to be governed by the meat component, the level of sulfite addition, or the fat content. However, the latter two factors are inversely correlated with the retention of sulfite in the foods analyzed.
Asunto(s)
Productos de la Carne/análisis , Ácidos Sulfónicos/análisis , Cromatografía Líquida de Alta Presión , Cianuros/farmacología , Ditiotreitol/farmacología , Productos Avícolas/análisis , Reproducibilidad de los Resultados , Sulfitos/análisis , Sulfitos/metabolismoRESUMEN
A method for the determination of sulfites in shrimp developed by Kim and Kim and modified by Paíno-Campa et al. for sausages has been further modified. Total sulfites are extracted by initially adding aluminum oxide to the sample and using an extraction solution at pH 12. In the reproducibility assays, coefficients of variation (CVs) were 4.8% for free sulfite and 7.8% for total sulfite in the edible part of the shrimp. In the inedible part, CVs were 7.5% and 8.9% for free and total sulfite, respectively. Mean recovery was 87.8% for the edible part and 84.4% for the inedible part of the shrimp. The method was compared with the optimized Monier-Williams method. The results obtained with both methods for determination of total SO2 in the edible part of the shrimp did not show significant differences (P = 0.05).
Asunto(s)
Decápodos/química , Sulfitos/análisis , Animales , Cromatografía Liquida , Concentración de Iones de Hidrógeno , Indicadores y Reactivos , Reproducibilidad de los ResultadosRESUMEN
Forty samples of fresh and fried burgers were analysed. A habitual use and often abuse of sulphites was detected. In the case of the uncooked samples, 62.5% contained residual levels of total SO2 above 450 micrograms/g. The frying process was found to lead to a mean reduction of 36.8 +/- 11.1% in the case of free sulphite and of 40.9 +/- 12.6% for total sulphite. This reduction was independent of the concentration of sulphite present and did not seem to be related to the type of meat used. Most burgers cooked in restaurants were found to contain sulphites, sometimes at elevated levels. The HPLC analytical method for the determination of sulphite contents in burgers, previously applied to fresh sausages, was compared with the optimized Monier-Williams method. The results obtained with both methods in the determination of total SO2 were found to have the same precision although there were significant differences in the contents of additive (p < 0.05).
Asunto(s)
Productos de la Carne/análisis , Sulfitos/análisis , Animales , Bovinos , Pollos , Cromatografía Líquida de Alta Presión , Calor , Productos Avícolas/análisis , Restaurantes , PorcinosRESUMEN
The urinary excretion kinetics of p-nitrophenol were studied in rabbits following oral administration of parathion at a dose of 3 mg/kg. Elimination of p-nitrophenol began rapidly, and of the total amount excreted during the study period, 46% was excreted in the first 3 h; 85% was excreted at 6 h after administration of the pesticide. The mean maximum excretion rate of p-nitrophenol was 111.15 +/- 61.02 micrograms/h reached in a time of 0.77 +/- 0.26 h. The formation and disappearance rate constants of the metabolite were 2.85 +/- 2.80 h-1 and 0.80 +/- 0.28 h-1, respectively. A linear relationship was observed between the plasma concentrations of parathion and the urinary excretion rate of p-nitrophenol.
Asunto(s)
Nitrofenoles/orina , Paratión/farmacocinética , Administración Oral , Animales , Masculino , Paratión/toxicidad , ConejosRESUMEN
The plasma kinetics of parathion were studied in rabbits after i.v. administration of a dose of 1.5 mg/kg and oral administration of 3 mg/kg. The time course of parathion plasma levels administered intravenously followed a three-compartment kinetic model statistically, whereas when administration was oral, the optimum kinetic model proved to be two-compartmental. The process of the absorption of parathion is very fast with a mean value for the absorption constant (ka) of 33 +/- 15.41 h-1. The slow disposition half-lives for i.v. and oral administration had mean values of 5.08 +/- 3.08 and 1.08 +/- 0.27 h, respectively. From the values established for the parameters defining the distribution process the wide accessibility of parathion to the different body organs and tissues may be seen. Although the compound has a high elimination constant, this process is not limiting to distribution.
Asunto(s)
Paratión/farmacocinética , Administración Oral , Animales , Inyecciones Intravenosas , Masculino , Paratión/administración & dosificación , ConejosRESUMEN
A previously described method to identify and quantitate serotonin in foods has been improved. The extraction and separation of serotonin from interfering substances has been improved, and the scope of material to which the method may be applied has been widened. The relative standard deviation (RSD) for repeated determinations of serotonin in canned fried tomato purée and the average recovery of serotonin added to the same sample was 6.25 and 89.9%, respectively. The method showed the presence of serotonin in apricots, cherries, and peaches.