The effect of pH on the simultaneous determination of Sulfamethoxazole and Trimethoprim by Ultraviolet Spectrophotometry and Multivariate Calibration

Analytical techniques based on Ultraviolet (UV) spectrophotometry are widely used in pharmaceutical analysis, because they are simple and inexpensive. The choice of pH is critical in the development of univariate methods for pharmaceutical quantitation by UV spectrophotometry since changes may modify the absorption spectrum profile. Similar to univariate methods by UV spectrophotometry changes in pH may influence the predictive ability of multivariate models, affecting the resultant analytical performance. We report herein on the influence of pH on the simultaneous determination of sulfamethoxazole (SMZ) and trimethoprim (TMP) in tablets using UV spectrophotometry and multivariate calibration. Data were recorded using a UV spectrophotometer in the wavelength range of 200 to 350 nm. The experimental matrix was constructed using 36 synthetic samples of SMZ-TMP mixtures. The concentration ranges used for the investigation were 14.0 to 26.0 mg L-1 for SMZ and 2.8 to 5.2 mg L-1 for TMP. The Partial Least Squares (PLS) regression models were generated with full-spectrum and multiple pH levels. At pH 4.3, lower values of relative standard error of prediction (RSEP %) for SMZ (1.83) and TMP (1.13) were obtained. The PLS model at pH 4.3 was used for the quantification of real samples (tablets obtained from 13 different manufacturers) and the results were compared with conventional procedures using high performance liquid chromatography (HPLC).

Determination of total sugar in raw coffee using near infrared spectroscopy and pls regression

In this work a fast method for the determination of the total sugar levels in samples of raw coffee was developed using the near infrared spectroscopy technique and multivariate regression. The sugar levels were initially obtained using gravimety as the reference method. Later on, the regression models were built from the near infrared spectra of the coffee samples. The original spectra were pre-treated according to the Kubelka-Munk transformation and multiplicative signal correction. The proposed analytical method made possible the direct determination of the total sugar levels in the samples with an error lower by 8% with respect to the conventional methodology.34635

Quantitative determination of sulphamethoxazole and trimethoprim in powder mixtures using raman spectroscopy and PLS

Raman spectroscopy in combination with partial least-squares (PLS) regression method was developed for sulphamethoxazole (SMZ) and trimethoprim (TMP) simultaneous determination in powder mixtures. The calibration set was designed with 18 samples and validation set with 9 samples, containing different SMZ and TMP concentrations. The concentration ranges were 400-900 mg/g for SMZ and 80- 240 mg/g for TMP. The proposed procedure was validated by comparison with the official method (HPLC). Mean root square error of calibration (RMSEC) and mean root square error of prediction (RMSEP) were calculated. RMSEC found was 30.96 mg/g to SMZ and 14.36 mg/g to TMP, respectively. RMSEP found was 25.60 mg/g to SMZ and 14.36 mg/g to TMP, respectively. Correlation coefficient (R2) was 0.99 for SMZ and 0.99 for TMP. This parameter evidences a very good agreement between estimated and real values. The results showed that PLS regression model combined with Raman spectroscopy provides a sensitive, fast and simple method for the quantitative analysis of SMZ and TMP mixtures in powder quality control.Colegio de Farmacéuticos de la Provincia de Buenos Aire

Miniaturized Method for Chemical Oxygen Demand Determination Using the PhotoMetrix PRO Application

The analysis of chemical oxygen demand (COD) plays an important role in measuring water pollution, but it normally has a high ecological price. Advances in image acquisition and processing techniques enable the use of mobile devices for analytical purposes. Here, the PhotoMetrix PRO application was used for image acquisition and multivariate analysis. Statistical analysis showed no significant difference in the results compared to the standard method, with no adverse effect of the volume reduction. The cost of analysis and waste generation were reduced by one third, while the analysis time was reduced by one fifth. The miniaturized method was successfully employed in the analysis of several matrices and for the evaluation of advanced oxidation processes. The AGREE score was improved by 25% due to miniaturization. For these reasons, the miniaturized PhotoMetrix PRO method is a suitable option for COD analysis, being less hazardous to the environment due to reductions in the chemicals used and in waste generation

Influência das condições de conservação nas características físico-químicas, sensoriais e microbiológicas de avelãs

Este trabalho focar-se-á na influência das condições de armazenagem nas características das avelãs cultivadas na região Centro de Portugal, de forma a potenciar a sua eficiente utilização, minimizar perdas pós-colheita e salientar as suas propriedades, assim como o seu contributo para a nutrição humana. Primeiramente serão analisadas três variedades de avelã (Grada de Viseu, Tonda de Giffoni e Butler) atendendo a parâmetros físico-químicos, caracterização sensorial e microbiológica. Posteriormente, serão realizados vários ensaios de conservação de avelãs, variando as condições de armazenagem (temperatura, humidade relativa e o tipo de embalagem). A monitorização das alterações nos frutos terá por base os mesmos testes que se realizaram para a caracterização de variedades, exceto a avaliação biométrica. Por fim, serão avaliadas as propriedades das avelãs após um processo de transformação, a torra. Com este estudo pretende-se, assim, aprofundar os conhecimentos sobre as boas práticas pós-colheita da avelã, diminuindo o seu desperdício, o que consequentemente permitirá aumentar a produtividade e o rendimento deste setor.This work will focus on the influence of storage conditions on the characteristics of hazelnuts grown in the Central region of Portugal, in order to enhance their efficient use, minimize post-harvest losses and highlight their properties, as well as their contribution to human nutrition. First, three hazelnut varieties (Grada de Viseu, Tonda de Giffoni and Butler) will be analysed according to their physicochemical parameters, sensory and microbiological characterization. Subsequently, several hazelnut conservation tests will be carried out, varying the storage conditions (temperature, relative humidity and type of packaging). The monitoring of the changes in the fruits will be based on the same tests that were performed for the characterization of varieties, except for the biometric evaluation. Finally, hazelnuts properties will be evaluated after the roasting transformation process. With good post-harvest practices, reducing their waste, which will consequently increase the productivity and income of this sector.info:eu-repo/semantics/publishedVersio