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Arsenic speciation in xylem sap of cucumber (Cucumis sativus L.) Received: 16 February 2005 / Revised: 29 April 2005 / Accepted: 8 May 2005 / Published ...
Anal Bioanal Chem (2005) 383: 461–466 DOI 10.1007/s00216-005-3325-y

S PE CI AL IS SUE PA PER

Victor G. Mihucz Æ Enik} o Tata´r Æ Istva´n Vira´g Edit Cseh Æ Ferenc Fodor Æ Gyula Za´ray

Arsenic speciation in xylem sap of cucumber (Cucumis sativus L.)

Received: 16 February 2005 / Revised: 29 April 2005 / Accepted: 8 May 2005 / Published online: 28 June 2005  Springer-Verlag 2005

Abstract Flow injection analysis (FIA) and high-performance liquid chromatography double-focusing sector field inductively coupled plasma mass spectrometry (HPLC-DF-ICP-MS) were used for total arsenic determination and arsenic speciation of xylem sap of cucumber plants (Cucumis sativus L.) grown in hydroponics containing 2 lmol dm 3 arsenate or arsenite, respectively. Arsenite [As(III)], arsenate [As(V)] and dimethylarsinic acid (DMA) were identified in the sap of the plants. Arsenite was the predominant arsenic species in the xylem saps regardless of the type of arsenic treatment, and the following concentration order was determined: As(III) > As(V) > DMA. The amount of total As, calculated taking into consideration the mass of xylem sap collected, was almost equal for both treatments. Arsenite was taken up more easily by cucumber than arsenate. Partial oxidation of arsenite to arsenate ( As(V) > DMA independent of the arsenic treatment. The amount of total As transported in the xylem was almost equal for both treatments. Arsenic speciation Table 1 Quantitative determination of total arsenic and of arsenic species with FIA and anion-exchange column HPLC-ICP-MS methods Type of As treatment

cAs (ng cm 2 lmol dm As(V)

for As(III), DMA, MMA and As(V) on the anion-exchange column were 0.20, 0.14, 0.30 and 0.34 ng cm 3, respectively. The detection limit for total arsenic by FIA was 0.1 ng cm 3. Although accurate comparison of the results obtained with the anion-exchange and cationexchange HPLC columns could not be performed due to

As(III) DMA As(V) Sum of arsenic species Total As as of FIA

22.78±1.1 0.99±0.1 2.53±0.2 26.3 29.5±1.0

3 3

± SD) 2 lmol dm As(III)

3

38.46±1.5 1.51±0.2 4.59±0.4 44.6 45.7±2.6

SD Standard deviation of three independent measurements of samples pooled separately for As(III) and As(V) treatment

466

studies of the nutrient solutions revealed that the occurrence of As(V) in the xylem sap of plant treated with As(III) was due to the partial oxidation of As(III) to As(V) in the nutrient solution (