Salvador Garrigues

Determination of total sterols in brown algae by Fourier transform infrared spectroscopy

A procedure is proposed for the determination of the total amount of sterols in brown algae Bifurcaria bifurcata, Cladostephus hirsitus, Dictyota dichotoma and Cystoseira sedoides, globally determined as fucosterol, which is the major sterol contained in these algae. The method involves the use of cholesterol as reference standard and a correction factor of 1.259+/-0.003, which represents the ratio between the slopes of calibration lines obtained from fucosterol and cholesterol. The method provides precise and accurate results for the IR analysis of real samples.

Simple partial least squares–attenuated total reflectance Fourier transform infrared spectrometric method for the determination of sugars in fruit juices and soft drinks using aqueous standards

A simple analytical procedure was developed for the direct determination of sugars in fruit juices (apple, orange, grape) and soft drinks. The method is based on the partial least squares treatment of attenuated total reflectance Fourier transform infrared spectrometric data obtained in the wavenumber range 4000–700 cm–1 and does not require any sample pre-treatment. Absorbance and first-derivative spectra were employed for measurements, using a reduced set of eight aqueous standard mixtures of glucose, fructose and sucrose at two concentration levels for calibration. The limits of detection found for absorbance measurements were 0.2 g per 100 ml for total sugar and 0.1, 0.1 and 0.03 g per 100 ml for glucose, fructose and sucrose, respectively. Relative standard deviations varied from 1.7 to 2.0% for six independent measurements of individual and total sugar concentration. In the analysis of real and synthetic samples, precise and accurate results were obtained, providing accuracy errors lower than 2% in all cases. Average recoveries of 96 ± 4% for total sugar and between 93 ± 7 and 99 ± 7% for single sugars demonstrate the applicability of the methodology developed to the direct analysis of fruit juice and soft drink samples.

FTIR-determination of sterols from the red alga Asparagopsis armata: Comparative studies with HPLC

An analytical procedure was developed for the determination of the total amount of sterols in the red alga Asparagopsis armata, globally determined as cholesterol, which is the major sterol contained in red algae. Samples, previously saponified with KOH were preconcentrated on DSC-18 solid phase cartridges (SPE) and eluted with dichloromethane stabilized with beta-amylene. Fourier transform infrared (FTIR) spectrometry was employed for selective detection at 1049cm(-1) with a baseline established between 1000 and 1079cm(-1). The results were compared to those obtained by high performance liquid chromatography (HPLC). The concentration obtained in actual samples from alga was 3.37% (w/w) by FTIR and 3.30% (w/w) by HPLC, showing a good comparability between the two methods.

CHAPTER 2:Direct Determination Methods Without Sample Preparation

The greenest alternatives to the traditional methods of analysis based on sample digestion and/or analyte extraction, are clearly those that permit the direct determination of as many analytes as possible without any sample pretreatment. This chapter deals with the main aspects and applications of remote sensing and teledetection systems, and the use of non-invasive methods of analysis, which permit a direct analysis of samples without any sample damage. In addition, the possibilities offered by several techniques to analyse solids directly without the use of reagents through the direct atomization of small portions of samples, the arc, spark or laser ablation of materials for their analysis by optical emission or mass spectrometry, are evaluated. This chapter attempts to provide a literature survey of all the aforementioned tools which have been evaluated from the perspective of greening analytical practices.

Chapter 1:An Ethical Commitment and an Economic Opportunity

This chapter introduces the main concepts of so-called green analytical chemistry and sets in a historical framework the main contributions and developments aimed at avoiding the deleterious side-effects of analytical chemistry and establishing the basis of environmentally friendly analytical practice. The authors thesis is that the future development of green analytical chemistry depends heavily on its two main characteristics: to be respectful to the environment and to offer new economic opportunities. Based on these two concepts it is easy to imaging the tremendous possibilities of greening the different methods of analysis and the use of the green criteria in all fields of application. So, in this preliminary chapter the reader will find topics that will be treated in depth in the subsequent chapters.