I want to know how to prepare the root samples of the plants after removing them from soils for heavy metals measurement. how to wash the roots and shoots? are there any recommended washing solutions? Are acid solutions recommended or not? what are the concentrations?
Any reason not to use plain demi water after manual sorting? I doubt any solvent will be recommended, as that will influence your plant material. Roots are nasty things to clean, I always tried to use the exact same sifting and cleaning method, to be sure that overall you have the same loss of root material while removing the soil.
[A]In soil washing techniques, where soil-bound contaminants are transferred to the liquid phase by desorption and solubilization, acid washing and chelator soil washing are the two most prevalent removal methods. Using a mixture of Na-2S2O5 and Na2EDTA provides more economically optimum solution than using Na2EDTA for heavy metal removal.
[B]The solid: liquid extraction method was investigated for removal of heavy metals from compost. Distilled water was added to the compost samples at a 2:5 ratio ( 4 g sample/10 mL distilled water) to determine the pH values of the samples. After being mixed by a magnetic mixer for 10 minutes, pH values were read using a pH meter.
[C]A 1-g compost sample was dried in a drying oven at 105C for 24 hours. The compost samples were weighed before and after the drying process in order to calculate the moisture by applying following relation:
Moisture % = (M1- M2)100/ M1 (1)
where M1 is the compost weight before drying (gram) and M2 is the compost weight after drying (gram).
[D]To determine the amount of heavy metals (Cu, Ni, Zn, Pb, Zn, Cd) and other elements (Ca, Na, Mg, K, P) in the compost samples, a screened, fresh compost sample was dried at 105 C and ground until reaching a grain size of 0.25 mm. Then, a compost sample weighing 1-2 g was placed in an Erlenmeyer flask and 10 mL 1:1 (V/V) water and HNO3 was added to perform the decomposition process.
[E]Following completion of decomposition process, the sample was cooled; 5 mL H2O2, 5 mL concentrated HCl and 5 mL water were added; and the sample was re-heated. After cooling, the sample was diluted with distilled water and filtered using a 0.45 μπι membrane filter. The resulting solution was analyzed to determine the presence and concentration of various elements .
REFERENCE:
Journal of Soil Science and Plant Nutrition, 2012, 12 (3), 525-534.
Any reason not to use plain demi water after manual sorting? I doubt any solvent will be recommended, as that will influence your plant material. Roots are nasty things to clean, I always tried to use the exact same sifting and cleaning method, to be sure that overall you have the same loss of root material while removing the soil.
the most easy way to work on dry weight
so you could wash it with with buffer and dry it then weight
and digest it then determine the metal
I'm conducting pot experiment and I have the same problem. I'm making procedure:
- hand separation of roots;
- 2 h shaking with distilled water
- ultrasound celaning
- drying in 105 C
No general recommendations. But you should remove soil particles from root samples. I am recommend gentle procedure. I can be deionized water or buffer solution, but not for long time.. For heavy metals it can work. If you are not sure about your procedure, you can test your washing solutions on heavy metals. Ultrasonic treatment is effective, but be sure that you are not loosing analytes from roots. Make comparison studies with pooled samples.
I agree with MIchel Vorenhout said. Any solvent that you use can influence your plant material. Wash gently with deionised water.
I divided the plant in situ if possible (greenhouse or during the field campaing sampling) in this way I can transport the plant samples with less external contamination of the aerial part. At the lab,after air drying (it is easier to remove dust particles, etc), the plant fractions were then thoroughly washed, first with tap water, followed by rinsing three times with deionised water. Then, we finisshed by cleaning them using an ultrasonic bath to remove external contamination (5 cycles of 5 minutes), sometime additional ultrasonic cycles is needed depending of the types or leaves or roots. Be careful if you are going to perform OMICs or plant physiological analysis, in this case, check that ultrasonic treatment don't interfere.
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