Determinação de nitrogênio em Peptídeos Farmacêuticos Ativos
A determinação do nitrogênio e da proteína total em produtos farmacêuticos está descrita nas seções 2.5.9 e 2.5.33 da Farmacopeia Europeia (Ph. Eur.) método 7 [1, 2]. Na Farmacopeia dos Estados Unidos (USP), a determinação de nitrogênio é descrita na seção 461 [3]. Nela, diferentes técnicas de titulação são especificadas. A Farmacopeia Europeia descreve a titulação reversa na presença da solução mista indicadora de vermelho de metila, e a USP, a titulação de ácido bórico potenciométrica.
The wet digestion is used to remove all carbonous material from the sample. The remaining inorganic content can be weighed out, resulting in the sulfated ash, or then be used for further elemental analysis. The digestion is performed using concentrated sulfuric acid while heating the mixture. The heat is ramped automatically using the BUCHI Wet Digester B-440. Once the sulfuric acid has digested the sample and is evaporated, the sample is eventually ashed in a muffle oven to remove any remaining organic material.
This application guide describes important aspects of the evaporation of solvents and the concentration of a sample to a predefined volume using the SyncorePlus. Guidelines for the evaporation of your specific solvent and solvent mixtures are presented. They will help you to streamline your own process with sample applications, checklists, hints, rules, tables, and tests.
Achieve higher distillation efficiency when using a rotary evaporator by reading on the impact of immersion angle.
The evaporation rate of a rotary evaporator depends to a large extend on the immersion angle of the evaporating flask. The flatter the immersion angle, the higher the evaporation rate. This is, among other reasons, due to the fact that a flat immersion angle increases turbulence inside the evaporating flask, hence accelerating the evaporation. However, with a flatter immersion angle the evaporating flask cannot be as deeply immersed in the heating bath medium compared with a steep immersion angle. This can be an issue especially working with smaller evaporating flasks. Generally speaking, a 40 degrees immersion angle leads to a maximum efficiency rate without restriction in handling or risking losing parts of the sample due to over spilling and bumping into the receiving flask.
Achieve higher distillation efficiency when using a rotary evaporator by reading on the impact of flask size.
Generally, the larger the evaporating flask the greater is the evaporation rate. This is due to the greater turbulence inside a larger flask, enlarging the active surface and leading to a higher evaporation output. On the other hand, smaller flasks are advantageous when the residue needs to be collected for further quantitative analyses. Moreover, larger flasks generally allow easier handling.