Résumé
@#Objective To develop and verify a chemical choromogenic method for the determination of residual cetyltrimethylammonium bromide(CTAB)content in ACYW135 meningococcal polysaccharide stock solution. Methods A chemical chromogenic method was developed for the determination of residual CTAB content by using titan yellow as chromogenic reagent,and verified for the linear range,intermediate precision and accuracy. ACYW135 meningococcal polysaccharide stock solution were determined for residual CTAB content by the developed method. Results The CTAB reference at concentrations of 4. 0～10. 0 μg/mL showed good linear relationship to A_(500),with a R~2 value of more than 0. 990. The recovery rates of CTAB standard at concentrations of 5. 0,7. 0,and 9. 0 μg/mL were all within 95% ～ 110% in six repeated tests,with the CV values of determination results of less than 10%. All the residual CTAB contents in four batches of meningococcal polysaccharide stock solutions were less than 8. 0 μg/mL. Conclusion The chemical chromogenic method showed good linearity,intermediate precision and accuracy,which might be used for the determination of residual CTAB content in ACYW135 meningococcal polysaccharide stock solution.
Résumé
El uso de biosurfactantes en biorremediación facilita y acelera la degradación microbiana de hidrocarburos. El método del agar CTAB/MB creado por Siegmund y Wagner para el screening de cepas productoras de ramnolípidos (RL), ha sido ampliamente utilizado sin sufrir mejoras significativas en más de 20 años. Con el fin de optimizar la técnica como método cuantitativo, se hicieron placas con agar CTAB/MB y se probaron diferentes variables, tales como tiempo de incubación, refrigeración, concentración de CTAB, presencia de azul de metileno, diámetro de los pozos y volumen del inóculo. Adicionalmente, se desarrolló un nuevo método para detectar el RL de los halos mediante precipitación con HCl, lo cual permite la observación de un nuevo patrón de halos más fáciles de observar y medir. Esta investigación reafirma que este método no es del todo apropiado para un análisis cuantitativo fino, debido a la dificultad de correlacionar de forma precisa la concentración de RL y el área de los halos formados. La difusión del RL no parece tener un comportamiento simple y existen numerosos factores que afectan la velocidad de migración del RL.
Use of biosurfactants in bioremediation, facilitates and accelerates microbial degradation of hydrocarbons. CTAB/MB agar method created by Siegmund & Wagner for screening of rhamnolipids (RL) producing strains, has been widely used but has not improved significantly for more than 20 years. To optimize the technique as a quantitative method, CTAB/MB agar plates were made and different variables were tested, like incubation time, cooling, CTAB concentration, methylene blue presence, wells diameter and inocula volume. Furthermore, a new method for RL detection within halos was developed: precipitation of RL with HCl, allows the formation a new halos pattern, easier to observe and to measure. This research reaffirm that this method is not totally suitable for a fine quantitative analysis, because of the difficulty to accurately correlate RL concentration and the area of the halos. RL diffusion does not seem to have a simple behavior and there are a lot of factors that affect RL migration rate.
Résumé
Melamine is a kind of triazine compound and the fluorescence of it can get enhanced in the presence of cationic surfactant in weak alkaline medium. A new fluorescent spectrophotometry based on this principle) has been developed to determine melamine under the optimum conditions such as Tris-HCl buffer solution), pH 8.0 and with CTMAB as sensitizing agent. The linear range, detection limit and relative standard deviation were 25-1000 μg/L, 19 μg/L and 1.6%,respectively. The samples were pretreated according to the solid phase extraction monolithic column to carry out the detection of real milk. This method is simple, rapid and accurate. It can be used to screen and detect the milk samples primarily.