A colorimeter method validation for rodhamine B
photodegradation assessment in cellulose acetate
nanofibers
Cândida Raquel Scherer Montero1, Sandra Jussara Nunes da Silva1,
Fernanda Stieven Soares1, Aline Procedi1, Patricia Pranke2, Renar João Bender 3,
Cláudio Nunes Pereira1
1- Tecnano Pesquisas e Serviços Ltda., Porto Alegre, RS, Brazil
2- Faculty of Pharmacy, Federal University of Rio Grande do Sul, Porto Alegre, RS,
Brazil
3- Faculty of Agronomy, Federal University of Rio Grande do Sul, Porto Alegre- RS,
Brazil
The incorporation and release of active ingredients from nanofibers is of great interest for
pharmaceutical and agricultural purposes. Due to their higher surface area to volume ratio,
nanofibers have been studied for drug delivery. Electrospinning is one of the most interesting
methods for drug delivery, and the nanofibers produced can also bring benefits to the area of
agriculture. One of the problems of nanoscale fibers is their high susceptibility to sunlight
exposure, leading to photocatalyctic degradation of the incorporated product. Volatile organic
compounds (VOC), such as those emitted by plants or even insects, like pheromone and
kairomone, are especially susceptible to this action. This compound attracts pests to the crops
and is used for insect control techniques. Being highly volatile, they lose their attraction
effects fast, so a formulation that gives a delayed delivery is desirable. Rhodamine B is a
known dye used for drug release assessment. The purpose of this work is to validate a
colorimeter method for rodhamine B photodegradation assessment in cellulose acetate
nanofibers. An electrospun nanofiber was produced with 1% rhodamine B in a 10 % solution
of cellulose acetate in acetone. Experiments for evaluation of rhodamine B nanofiber samples
were carried out at room temperature and exposed to light from a window for 63 days.
Electrospun readings of molecular absorption at 563 nm were realized using a UV
spectrophometer (Shimadzi UV-1700) and with a Minolta colorimeter. The colorimetric data
was presented as the values of a*, b* and hue angle (components of colour blend) .
Correlation analysis was performed with data of the colorimetric assessment and the
spectrophotometer. Data of the spectrophotometer shows that Rhodamine B degradation
occurs faster when exposed to light. The colorimetric methodology also shows the same
pattern at a 1% level of significance.A significant relation between the colorimeter and the
molecular absorption spectrophotometer results was found. The hue angle parameter is the
most suitable for nanofiber analysis. The photodegradation assessment measured by the
colorimeter was validated by the authors and in this study, the photodegradation of rhodamine
B was measured by the colorimetric hue angle, which is a much faster and non destructive
analysis method.
Keywords: Rhodamine B, electrospinning, nanofiber, light exposure
Work supported by CNPq and FAPERGS