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A method for the determination of trace amounts of beryllium has been developed, based on ion-exchange spectrofluorimetry. Beryllium reacts with morin to give a highly fluorescent complex, which was fixed on a dextran-type anion-exchange resin. The fluorescence of the resin, packed in a I-mm quartz cell, was measured directly using a solid-surface attachment. The concentration range of the method is 0.10-0.70 pg 1-1, the relative standard deviation 1.4% and the detection limit 0.02 pg I-'. The method was applied to the determination of beryllium in natural waters. The aluminium and calcium levels can be determined first in order to reduce their interfering effect. The proposed method is more sensitive and selective than that using morin alone.

A new, sensitive and simple spectrofluorometric method for the determination of thiabendazole (TBZ) residues was studied. TBZ on Sephadex G-15 gel, pH 4.70 acetate buffer, is fixed to give fluorescence. The fluorescence of the gel-TBZ system, packed in a 1-mm quartz cell was measured directly using a solid-surface attachment. The applicable concentration range was 1.5-10.0 ng.mL-1 with a relative standard deviation of 1.4% and a detection limit of 0.1 ng.mL-1. The method was applied to the determination of thiabendazole in natural, waste, sea, and residual waters (98-100% recovery). The method is more sensitive and selective than other methods described in the literature. The presence of other fluorescent pesticides (dichlone, carbaryl, morestan, o-phenylphenol) with similar spectral features (lambda exc and lambda em neighboring to excitation and emission wavelengths of the TBZ) did not cause interference.

Abstract.A spectrofluorimetric method for the determination of aluminium at ng/ml level has been developed. The method is based on the formation of a fluorescent 1 : 1 complex between AI(III) and 2,6-bis [(o-hydroxy)phenyliminomethyl]-l-hydroxybenzene at an apparent pH of 5.0 in an aqueous-ethanol medium (70% v/v ethanol). The influence of reaction variables is discussed. The range of concentration of the method is 1.0-10.0 ng/ml aluminium, the relative standard deviation 1.5% and the limit of detection 0.1 ng/ml. The advantages of the proposed method include high sensitivity and selectivity. The method has been applied to the determination of Muminium in natural waters.Key words: spectrofluorimetry, aluminium determination, natural waters, 2,6-bis[(o-hydroxy) phenyliminomethyl]-l-hydroxybenzene.Assays for aluminium in body fluids and water have taken on considerable importance over the past few years, ever since the metal was first suspected of being involved in cases of encephalopathy in patients with renal insufficiency treated by dialysis [1][2][3].Aluminium toxicity is also associated with osteomalacy and osteodistrophy [4,5], anaemia [6,7], gastrointestinal symptoms [8] and possible cardio toxicity [9] features.The determination of aluminium in waters is desirable, as the most important source of this element in patients with renal failure is the water used for dilution of dialysis solutions [10,11].Commercial aluminium salts are used as flocculants in water-treatment plants; aluminium sulphate, chloride and chlorosulphate are the most commonly employed. This implies that flocculation with commercial aluminium salts increases the aluminium content in tap water.Aromatic Schiff's bases of salicylidene-o-aminophenol (I) type have been extensively proposed for the spectrofluorimetric determination of metals, through forma-

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