The sensitive method DPASV with HMDE in the presence of DTPA and acetic buffer was used for determination of Tl(I) and Tl(III) in spiked seawater sample. The proposed method was based on the appropriate chemical conservation of Tl speciation. To determine the total amount of Tl, an addition of ascorbic acid to sub-sample was necessary, but to determine Tl(I) to the second sub-sample addition of DTPA was needed. Various factors influencing the stability of Tl(III) and electrochemical parameters were investigated. The quantification limit of 1.8 ng mL À1 Tl(I) was found for 8 min preconcentration. The procedure was validated using recovery study and HPLC ICP MS determinations.

No abstract

Cathodic stripping voltammetry (CSV) with a hanging mercury drop electrode (HMDE) was applied to the determination of arsenic content in samples of nettle plants growing in the area characterized by contamination of anthropogenic origin. The arsenic determinations, preceded by As(V) to As(III) reduction, were carried out in acidic medium in the presence of Cu(II). The plant material digestion was conducted in a HNO 3 aHClO 4 mixture using a modi®ed pressurized microwave decomposition method to improve the sensitivity 10-fold. ETAAS technique was used as a reference method. The whole procedure was tested on OTL 1 (Tobacco leaves) certi®ed reference material.

A very sensitive procedure for the determination of platinum in hydroponically cultivated plant samples (Sinapis alba L and Lolium perenne) is presented. A microwave digestion with HNO 3 , HClO 4 and HCl acids with additional UV irradiation is followed by the platinum determination by adsorptive stripping voltammetry at hanging mercury drop electrode. The influence of HNO 3 acid on voltammetric determination of platinum is discussed. For validation of the obtained results the recovery of Pt was examined and the Pt determination by ICP MS was carried out. The highest platinum amounts were found in the roots of the plants, nevertheless the effective transport of platinum to the steams and leaves was also observed.

Experimental parameters for determination of aluminum (up to 15 ppb) were evaluated in acetate (pH = 4.2) and borate (pH = 8.9) buffer solutions. Because the reaction of Calmagite in acetate buffer requires heating (10 min, 90°C) the total analysis time is relatively long. This inconvenience is circumvented by using a borate buffer. The complexation reaction is nonspecific in both media. Iron( 111) should be reduced using hydroxylamine hydrochloride, whereas copper( 11) and some other metals may be eliminated by electrolysis. The developed method was used for aluminum determination in reference material-flour V-8 (m-Vienna), tap water, and commercial 4% acetic acid before and after boiling in an aluminum pot. UVTRODUCTIONRecently, among various instrumental analytical methods for determination of trace amounts of aluminum, adsorptive stripping voltammetry has also been applied. In such procedures the aluminum complex with selective ligands, at a proper potential, is adsorbed at the stripping mercury drop electrode; next, the ligand bound in a complex is reduced, giving a peak related to the metal amount. For such a determination Wang and co-workers [ 1-21 applied the aluminum complex with Solochrome Violet RS (142-hydroxy-l-naphthylazo)-2-hydroxybenzene-5-sulfonic acid). Our laboratory used this process to determine aluminum traces in dialysis solutions for renal failure treatment [3]. Van den Berg and co-workers [4] used a procedure for analysis of fresh and sea waters based on a similar principle but with 1,2-dihydroxy-antraquinone-3-sulfonic acid as a ligand.Because of the unfavorable kinetics of Al-Solochrome Violet RS complex formation and numerous interferences, an attempt was undertaken, in this study, to apply another ligand, namely Calmagite (l-hydroxy-4-methyl-2-phenylazo)-2-naphthol-4-sulfonic acid). Bem and Rubel [ 5-81 used Calmagite for indirect polarographic determination of aluminum in several materials based on splitting the reduction wave of this ligand in the presence of aluminum. They investigated and estimated the composition of AlCalmagite complexes and their electrochemical parameters. The range of polarographically determined concentrations was 0.1-14 mg/dm3 of aluminum. This article 'To whom correspondence should be addressed.8 1992 VCH Publishers, Inc presents a stripping procedure that focuses on ultratrace determination of significantly (3 orders of magnitude) lower levels of aluminum, as desired for ecological and toxicological diagnosis. EXPERIMEhTAL ApparatusPolarographic measurements were carried on in a threeelectrode system; hanging mercury drop electrode (HMDE), (IChF, PAN, Poland), saturated calomel electrode (SCE), and platinum wire.Polarographic analyzer, Model 174A (PAR, USA) with XY recorder-RE0089 (PAR, USA) was employed. A pHmeter, type N 5122 (Mera-Elmat, Poland), was also used. Reagents and SolutionsAcetic acid (96%, d = 1.061 g/cm3), perchloric acid (70%, d = 1.67g/cm3), hydrochloric acid (30%, d = 1.15 g/cm3), ammonia (25%, d = 0.91 g/cm3), sodium hydroxide-a...