The performance of inductively-coupled plasma optical emission spectrometers with axial and radial views for determination of iodine in table salt was evaluated. Interference and memory effects in nitric acid and water-soluble tertiary amines (CFA-C) media were studied. Based on a factorial experiment, one optimum instrument operational condition for axial configuration, and two optima conditions for radial configuration was established. The ICP OES with axial view was 5-fold more sensitive than the radial view. Both matrix matching and standard addition methods were used for iodine quantification and for most samples, both strategies of calibration led to similar results. Recoveries ranged from 104 to 114%.

Quantitative analysis of colored substances is generally performed using a spectrophotometer for detection of radiation. However, the combination of digital images and mathematical conversion of colors is an alternative for quantitative procedures based on colored chemical reactions. This work proposes a didactic experiment using a scanner for determination of ascorbic acid in medicines based on the formation of the Prussian blue complex. Results were in good agreement with a conventional spectrophotometer method and the procedure is attractive for instrumental analysis undergraduate courses.

Geralmente aceita-se que espectrômetros de emissão óptica com plasma acoplado indutivamente (ICP OES) com configuração axial apresentam efeitos de matriz mais severos quando comparados aos equipamentos com configuração radial, embora gerem menores limites de detecção. Entretanto, o desenvolvimento de detectores de estado sólido associado ao arranjo óptico Littrow com rede echelle e interfaces apropriadas para remoção da zona fria do plasma vêm possibilitando a expansão do uso dessa configuração. Nesta revisão são discutidos trabalhos publicados no período de 1999 a 2006 que fazem uso da configuração axial para avaliação dos efeitos de matriz, otimização das condições de operação e análise de diversos tipos de amostras, incluindo a introdução de amostras complexas, tais como suspensões.

It is generally assumed that inductively coupled plasma optical emission spectrometers (ICP OES) with axial configuration present severe matrix effects when compared to radially viewed ones, although lower detection limits are obtained. However, the development of solid state detectors associated with a Littrow optical arrangement with an echelle grating and proper interfaces for plasma tail cut off led to an increase of analytical applications based on axially viewed configuration. In this review, papers published from 1999 to 2006 using this configuration for matrix effects evaluation, optimization of the operating conditions and analysis of complex samples, such as slurries, are discussed.

Simple experiments are proposed for measuring molecular absorption of chromate and dichromate ions using an atomic absorption spectrometer. The experiments can help undergraduate students in instrumental analysis courses understand important aspects involving conceptual and instrumental similarities and differences between frequently used analytical techniques. Hollow cathode lamps were selected with wavelengths in the region of molecular absorption of chromate and dichromate. Calibration curves were obtained and the linear dynamic range was evaluated. Results were compared with those obtained in a molecular absorption spectrometer. The molar absorptivities obtained were also compared.