Zobrazeno 1 - 10
of 11
pro vyhledávání: '"Hilda Ledo de Medina"'
Autor:
Julio Cesar Marín Leal, María Elena Romero González, Marinela Colina de Vargas, Hilda Ledo de Medina
Publikováno v:
Revista Técnica de la Facultad de Ingeniería, Vol 20, Iss 2 (2011)
Pigrnents such as chlorophyll. pheophytins and carotenoids are originated from organic vegetable matter and therefore can provide irúonnation about the load of deposition of organic matter in sediments. Concentrations of these pigrnents. as well a s
Externí odkaz:
https://doaj.org/article/d904d7c8192849a99c7b1e739bbc1947
Publikováno v:
Flow Injection Analysis of Food Additives ISBN: 9780429170300
A food additive is usually dened in the literature as an ingredient added to food as a part of its production (Furia, 1968; Branen et al., 1990). The use of food additives is normally regulated by the corresponding authorities and governmental organi
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::57aff3b8f9d7eaee0f1048afde9ba3ae
https://doi.org/10.1201/b19644-24
https://doi.org/10.1201/b19644-24
Publikováno v:
Water, Air, and Soil Pollution. 145:341-357
Nitrogen is one of the two most important elements in the metabolism of aquatic eco- systems. At low concentrations it can limit primary productivity and when present at very high concentrations it can participate in the eutrophication process of the
Publikováno v:
Hydrobiologia. 450:47-55
The distribution of phosphate species in the Catatumbo River, Venezuela, was studied using a sequential extraction scheme. Extraction was performed using 1.0 M NH4Cl, 0.1 M Na2S2O4–NaHCO3, 1.0 M NaOH and 0.5 M HCl. Total phosphate was in the range
Publikováno v:
Water, Air, and Soil Pollution. 117:27-37
Nitrogen (N) and phosphorus (P) concentrations were determined in sediment samples along the bed of Catatumbo river in both Colombian and Venezuelan territories until the river outlet in Maracaibo lake. Total phosphorus was determined by digestion wi
Autor:
Graciela González, Elizabeth Gutiérrez, Julio Marín, Marinela Colina de Vargas, Eduardo Andueza, Hilda Ledo de Medina
Publikováno v:
Journal of Chromatography A. 739:207-215
Phosphorus in aquatic systems is generally considered the limiting nutrient in most of cases. Its concentration may be below 0.01 mg/l. The sensitivity of the standard method for phosphate with ascorbic acid does not allow its determination in these
Publikováno v:
Journal of Chromatography A. 671:287-293
The standard method for the determination of organic nitrogen in water samples in the past has been based on the Kjeldahl digestion technique that converts organic nitrogen into ammonia, which can then be determined along with any ammonia originally
Autor:
Hilda Ledo de Medina, Harvi Velásquez, Magaly Santana, José Morales, Marlene González de Nava
Publikováno v:
Journal of Chromatography A. 671:193-196
Ion-exchange chromatography with a Dionex Model QIC system was used to identify and determine formic and acetic acid in event rains collected at the La Esperanza site (Zulia, Venezuela). Pyruvic acid was observed infrequently and always at very low c
Publikováno v:
Analytical Letters. 27:625-641
This paper describes a potentiometric method for the determination of sulphur in solid and liquid samples, using a sulphide ion selective electrode after the reduction distillation step. The determination of sulphide in solid and liquid samples witho
Autor:
Elizabeth Gutiérrez, Enrique Villalobos, Marinela Colina de Vargas, Hilda Ledo de Medina, Roman Mazurek
Publikováno v:
The Analyst. 120:761
The standard method for the determination of organic nitrogen in water samples has in the past been based on Kjeldahl's digestion technique which determines nitrogen in the triply negative state. In the presence of sulfuric acid, potassium sulfate, m