No abstract

No abstract

Folic acid (FA) or pteroyl-L-glutamic acid, chemically known as N-[4-[[(2-amino-1,4-dihydro-4-oxo-6pteridinyl)methyl]amino]benzoyl]-L-glutamic acid, is a water-soluble B vitamin that helps build healthy cells. In this study, a new, simple, easy, accurate, precise, economic and sensitive UV spectrophotometric method for the determination of folic acid in commercial tablets and during dissolution tests is presented. Using a phosphate buffer solution at pH 9.0 it was possible to determine the concentration of folic acid in commercial tablets at a l max of 282.5 nm in a linear range of 1.0-17.5 mg ml À1 with a R 2 > 0.9999 and recovery between 100.6 and 101.1%. The method was also optimized for the quantification of folic acid in dissolution tests in the same linear concentration range. The pH effect on the UV spectra of folic acid solutions was eliminated with a first derivative. This procedure allowed the direct measurement of samples from the dissolution vessel (pH approximately equal to 6) without any pH correction. This method was based on the first derivative of the absorbance at l ¼ 377.2 nm, yielding an R 2 > 0.9997 with recovery percentages similar to those presented before. The statistical comparison between the proposed and the HPLC reference method showed excellent agreement and indicates no statistically significant difference in accuracy and precision at a 0.05 significance level.

The performance of an activated sludge reactor can be significantly enhanced through use of continuous and real-time process-state monitoring, which avoids the need to sample for off-line analysis and to use chemicals. Despite the complexity associated with wastewater treatment systems, spectroscopic methods coupled with chemometric tools have been shown to be powerful tools for bioprocess monitoring and control. Once implemented and optimized, these methods are fast, nondestructive, user friendly, and most importantly, they can be implemented in situ, permitting rapid inference of the process state at any moment. In this work, UV-visible and NIR spectroscopy were used to monitor an activated sludge reactor using in situ immersion probes connected to the respective analyzers by optical fibers. During the monitoring period, disturbances to the biological system were induced to test the ability of each spectroscopic method to detect the changes in the system. Calibration models based on partial least squares (PLS) regression were developed for three key process parameters, namely chemical oxygen demand (COD), nitrate concentration (N-NO(3)(-)), and total suspended solids (TSS). For NIR, the best results were achieved for TSS, with a relative error of 14.1% and a correlation coefficient of 0.91. The UV-visible technique gave similar results for the three parameters: an error of approximately 25% and correlation coefficients of approximately 0.82 for COD and TSS and 0.87 for N-NO(3)(-) . The results obtained demonstrate that both techniques are suitable for consideration as alternative methods for monitoring and controlling wastewater treatment processes, presenting clear advantages when compared with the reference methods for wastewater treatment process qualification.

No abstract

No abstract

No abstract

No abstract