<p>A Multivariate Image Analysis (MIA) laboratory activity was proposed estimating pH of drinking water samples from its digital images after adding bromothymol blue as a pH indicator, and using the PLS multivariate calibration method. All computational work was done using GNU Octave free software. The MIA-PLS based approach exemplified with drinking water pH estimates is tailored to meet the needs of both students and researchers. MIA-PLS method was statically equivalent to the reference method using a conventional glass pH electrode. This lab activity combines analytical methodology, computing, and chemometrics.</p>

In 1996, the LDB (Law of Guidelines and Bases of Education) established that only graduated teachers are allowed to teach in Brazilian public high schools after 2007. Goiás public high schools have been facing changes in chemistry teacher level profile since then. Principal component analysis and Hierarchical cluster analysis have been applied as alternative research tools in Education in order to more rapidly assess similarities in the level of chemistry teachers in all regional offices of education. Chemometrics analysis on 2003 and 2007 chemistry teacher cadastral database supplied by the Goiás State Department of Education revealed a change in high school chemistry teachers forward to PIII level (stable job; graduated; teaching degree). In 2003, nine out of all thirty seven regional offices of education in the state had more than 50 % of its chemistry teachers having academic degree (PIII and PA-D levels). In 2007 all thirty eight regional offices achieved this figure. In 2003 no regional office had teachers having a master degree and in 2007 this number raised to thirty regional offices. Despite a significant increase in the number of qualified teachers it still stays far below demand.

En 1996 la Ley de Directrices y Bases de la Educación (LDB) estableció que a partir de 2007 se permitiría enseñar en los bachilleratos públicos brasileños sólo a profesores graduados. Los bachilleratos del estado de Goiás han encarado desde entonces cambios en el perfil de sus profesores. El "análisis de componentes principales" y el "análisis de cúmulos jerárquicos" han sido las técnicas aplicadas como investigación alternativa para evaluar similitudes en el nivel de los profesores de química de todas las oficinas educativas regionales. El análisis quimiométrico en 2003 y 2007 desarrollado con el instrumento proporcionado por el Departamento de Educación del Estado de Goiás ha revelado un cambio de los profesores de química del bachillerato hacia el nivel llamado PIII (trabajo estable, graduado, con grado obtenido para la enseñanza). En 2003 nueve de las treinta y siete oficinas de educación del estado tenían más de 50 % de los profesores de química con grado (niveles PIII y PA-D). En 2007 todas las treinta y ocho oficinas regionales llegaron a esa cifra. En 2003 ninguna oficina regional tenía profesores con grado de maestría y en 2007 ese número subió a treinta oficinas. A pesar del crecimiento en el número de los profesores calificados, ello todavía permanece por debajo de lo demandado.

This paper describes an approach for the colour-based classification of RGB (red-green-blue) images, acquired using a common scanner, of commercial carbonated soft drinks. Mean histograms of image colour channels were evaluated for the PCA classification of 29 brands of Guaraná, Cola, and orange flavors. Loadings for principal component axes resulted in different patterns for sample grouping on score plots according to RGB histograms. pH, sorbic acid and sucrose measurements were also correlated to the analyzed brands through PCA score plots of the digitalized images.