Materials and Reagents

1. Rice tissue (roots, shoots, husks) (Muehe et al., 2014)
   
2. Liquid nitrogen
   
3. 65% HNO₃ (Merck KGaA, catalog number: 100456 )
   
4. Double-distilled or MilliQ water
   
5. >30% H₂O₂ (Merck KGaA, catalog number: 107298 )
   
6. 85% phosphoric acid (Merck KGaA, catalogue number: 100563 )
   
7. 0.05 mol/L as stock solution as arsenite (Merck KGaA, catalog number: 106277 ), a 1,000 mg/L as stock solution as arsenate (Merck KGaA, catalog number: 119773 ) diluted to the appropriate concentrations
   
8. NH₄NO₃ (Merck KGaA, catalog number: 102596 )
   
9. Eluent A for LC-HPLC-ICP-MS (see Recipes)
   
10. Eluent B for LC-HPLC-ICP-MS (see Recipes)
    

Equipment

1. Mortar (diameter of at least 10 cm) and pestle (approximately 15 cm long)
   
2. Drying oven (adjustable to 60 °C)
   
3. Whatman^TM #1 filter papers (GE Healthcare, catalog number: 1440-125 )
   
4. Duran^® test tubes, straight rim (13 x 100 mm) (Duran Group, catalog number: 26 131 12 )
   
5. Polyethylene flanged plug caps for tubes, natural (Globe Scientific, catalog number: 118240 )
   
6. Polytetrafluoroethylene (PTFE)-coated spatula (Fisher Scientific, catalog number: 10081074 ) to minimize metal contamination of the plant material from the spatula
   
7. Volumetric flask with glass stopper (10 ml)
   
8. Tube rack
   
9. Water bath
   
10. Glass funnel
    
11. Inductively coupled plasma atomic emission spectrometry ICP-AES (CIROS)
    
12. Inductively coupled plasma mass spectroscopy ICP-MS (Agilent Technologies, model: 7700 )
    
13. Autosampler vials (8 mm, brown glass, WICOM, vials are free of As) and screw caps with Teflon septum
    
14. Liquid chromatography (Agilent Technologies, model: 1200 ) equipped with a Shodex RSpak NN-614 column (150 mm x 6 mm; Shodex) coupled to inductively coupled plasma mass spectroscopy HPLC-ICP-MS (Agilent Technologies, model: 7700 )
    

Procedure