Antoni Rius

Standardization of a multivariate calibration model applied to the determination of chromium in tanning sewage.

A multivariate standardization procedure was used to extend the lifetime of a multivariate partial least squares (PLS) calibration model for determining chromium in tanning sewage. The Kennard/Stone algorithm was used to select the transfer samples and the F-test was used to decide whether slope/bias correction (SBC) or piecewise direct standardization (PDS) had to be applied. Special attention was paid to the transfer samples since the process can be invalidated if samples are selected which behave anomalously. The results of the F-test were extremely sensitive to heterogeneity in the transfer set. In these cases, it should be taken as an interpretation tool.

Time series: a complementary technique to control charts for monitoring analytical systems

Abstract In this study, the time series method was used as a complement to the most common control charts (X and R charts) to monitor a sequential injection analysis (SIA) system with UV/visible detection for determining sulphates in water. Time series confirm the most important results of control charts and provide better understanding of how the system behaves over time. They provide information about the possible relationship between one datum and the previous data in the series. This opens up more realistic possibilities if an out-of-control point has to be substituted (once what has caused it is known) or if some missing data have to be evaluated. They also provide information for reducing the frequency of the analysis, if this proves necessary, and for avoiding autocorrelation in the data.

Use of Rapeseed Straight Vegetable Oil as Fuel Produced in Small-Scale Exploitations

This chapter presents a method to produce rapeseed and process it to obtain rapeseed oil and rapeseed cake meal from a small-scale point of view. It also shows how rapeseed oil can be used as fuel in diesel engines for agriculture self-consumption. A production, processing and use-as-fuel model for rapeseed oil is also presented, analysing environmentally and economically the use of rapeseed oil as fuel compared to other agricultural production alternatives. The results are evaluated for dry Mediterranean area conditions