Determination of gallium in aluminium oxide by atomic absorption spectrometry with electrothermal atomisation: effect of gallium bond and aluminium oxide modification on the analytical signal under slurry atomisation conditions

Abstract

A method is reported for the determination of gallium in a-alumina powder (corundum) by electrothermal atomisation of the sample introduced in the form of a suspension (slurry) into a graphite atomiser, either on the wall or a platform [ l o pI of 0.25% mlv suspension in ethanolwater (9 + I)]. The measurements were carried out at 294.4 nm with deuterium background correction. For calibration, standard oxides were prepared either with gallium occluded within the alumina matrix or adsorbed on alumina present in the a-or y-modification. It was found that alumina decreases markedly the volatility of gallium and increases the sensitivity of the determination in comparison with aqueous nitrate solutions containing no aluminium (ca. 8-fold when atomised from the wall for gallium occluded within a-alumina). The mini-platform effect of alumina on the atomiser wall is considered to be the main reason for the increase in peak size. When atomising from the platform, the peak of gallium occluded within a-alumina exhibits a time delay of about 500 ms compared with y-alumina. Based on the ascertained dependences of the atomisation signal on several variables (including the mode of combining gallium with alumina, i.e., occlusion or adsorption), suitable procedures for correct Cali bration are suggested.

ETAAS determination of gallium in soils using slurry sampling

“…Gallium and its compounds are used in a variety of high technology applications and, consequently, the levels of the element in the environment are gradually increasing. 1 Electrothermal atomic absorption spectrometry (ETAAS) has been used for the determination of gallium in different samples [2][3][4][5][6][7][8][9][10][11] but, to the best of our knowledge, the literature contains only one paper dealing with its determination in soils. 12 The determination shows a number of problems 13 and nickel is the most commonly used chemical modifier.…”

“…Such an approach, which was first used by Bendicho and de Loos-Vollebregt, 18,19 allows a fraction of the analyte to be leached from the solid sample to the liquid phase and facilitates silicon removal during the heating cycle. The literature reports three papers describing slurry-ETAAS procedures for gallium determination 5,6,12 but none, even the detailed report recently published by Langodegard and Wibetoe 12 that especifically deals with the determination in soils, takes advantage of the use of hydrofluoric acid in the suspension medium.…”

Atomic absorption, atomic emission, and flame emission spectrometry

“…The carbon remaining after pyrolysis of the polymer aided the reduction process and prevented vaporization of molecular species. An aluminum oxide matrix was also shown to stabilize Ga (431). There were several reviews of the applications of slurry-ETAAS (82,432,433), and Miller-Ihli (434) described some of the strategies for its use.…”

Simultaneous determination of chromium and manganese in alumina by slurry sampling graphite furnace atomic absorption spectrometry using NbC and NaF as modifiers

“…Cr 3+ ) to alumina leads to spectacular colors, gem stones, and practical applications such as ruby lasers. 7 Trace element determination in aluminium-based matrix have been performed by high sensitivity spectrochemical techniques, such as graphite furnace atomic absorption spectrometry (GF AAS), [8][9][10][11][12][13][14][15] inductively coupled plasma optical emission spectrometry (ICP OES) [16][17][18][19][20][21] and inductively coupled plasma mass spectrometry (ICP-MS). 22,23 Acid digestion procedures for alumina analysis may have some characteristics that become their application hard in routine analysis: (i) the time spent for total digestion is too long (around 4 h), (ii) the possibility of contamination or analyte volatilization in each one of the successive steps, (iii) sometimes the incomplete sample decomposition and (iv) additionally, the final acidity of the digestion product could cause some drawbacks, depending on the analytical technique used for measurements.…”

“…16,20 Alternatively, direct solid analysis can be more attractive and, for high purity samples, presents advantages over the conventional procedures of dissolution: (i) shortening the sample preparation time (good for routine analysis), (ii) less sample contamination and decreased losses of analyte, (iii) prevents the use of hazardous and corrosive reagents, (iv) improve the detectability of method, and (v) it is a clean method of analysis. 24,25 The majority of the direct methods mentioned above for the determination of impurities in alumina-based matrix use slurry 8,9,11,14 and direct solid 12,15 sampling for GF AAS and slurry sampling combined with electrothermal vaporization for ICP OES 20,21 and ICP-MS. 22,23 Also, a direct aluminium oxide analysis by continuous powder sampling into microwave induced plasma optical emission spectrometry (MIP OES) has been reported in the literature. 26 Compared with ICP OES and ICP-MS, GF AAS is well suited for the direct analysis of solids.…”