Um fotômetro LED-NIR duplo feixe microcontrolado e portátil para análise screening e quantitativa de medicamentos injetáveis de forma não invasiva

Abstract

In this work, a portable LED - NIR double beam micro-processor controlled photometer for non-destructive/non-invasive screening and quantitative analysis of injectable medicines was developed to assess conformity with values established by the Brazilian Pharmacopoeia. The product analyzed was injectable dipyrone (1g/2 mL) sold in amber colored vials of 1.1 cm outer diameter, and 6 cm in height. Initially, spectroscopic studies were carried out employing a commercial spectrophotometer to assess the best NIR spectrum regions that might be used. The instrument developed used two twin LEDs with NIR radiation emissions rated at 1050 ± 50 nm. Two InGaAs photodiodes (also identical), and a PIC18F455 microcontroller were used as well. The output of the instrument used a PIC microcontroller coupled to a 20x2 liquid crystal display which communicated with a PC by USB 2.0 for communication. The instrument evaluated commercial dipyrone injection samples using absorbance measurements made directly from ampoules of the injectable medicines. The photometer was calibrated with standard solutions of dipyrone, and its performance was evaluated by an analysis of 620 of the commercial dipyrone injection samples, where 320 were expired. The instrument had a high success rate for screening analysis (91%). For quantitative determination of the active dipyrone, a linear response was obtained [R2 = 0.9964, A = 0.0068 + 0.0043 C (% w/v)] in the concentration range of 5 to 60% m/v. We also obtained a low relative error of 0.40%, and good accuracy in the analyses with a relative standard deviation of 2.13%.