Please include all necessary procedures and sample preparation (e.g wet digestion, dry ashing, etc.). If you have methods derived directly from AOAC, published article, or other standard handbooks, the better. Please help me in consolidating these methods so I can use them in my graduate analytical course involving AAS analysis.
This article should also be helpful, "Comparison of Four USEPS Digestion Methods for Trace Metal Analysis Using Certified and Florida Soils" by Chen and Ma. Journal of Environmental Quality vol. 27, issue 6 (1998) pp.1294-1300.
The paper shows the strengths and weakness of several different standard digestion procedures used by the United States Environmental Protection Agency.
Thanks for sharing some valuable articles regarding my request. Do you have copies of that articles? Please email it to me at [email protected]. Regards!
Low amounts of Pb and Cd after wet ashing can be determinedspecifically according to the method used several decades and discribed later by a student of mine.
Iskandar, Petersson L., Frank A. Determination of lead and multi metal in tissue samples using methyl isobutyl keton extraction and atomic absorption spectrometry.
Indon J. Trop Agric §998;3:14-19
If you have difficulties to get the artcle I can send you PDF file.
Regards
Thanks Dr. Frank. I have limited access to some journal articles here in our institution. Kindly send the paper at [email protected].
Dr. Garcia-Delgado and Dr. Dukes, I already received your papers. Thank you very much!
Thank you for the email attachment Dr. Frank. Thanks for all your valuable input.
hi dear, your question is depends on many things.first how much you want to digest? and the important one is the detection limit and the dynamic range of your method. and then you can digest the amounts of plant. the way i suggest was written in hand book of AAS. you can digest 1gr of plant tissue in 5ml HNO3+2ml HClO4 then heated on the heater stirrer until digestion (the volume of the solution should be 3ml at the end till toxic NO is removed and the solution become colorless or yellow) after that the digested sample solution was cooled to room temperature. thenfiltered and added distilled water in a volum of 50ml.in this step your digestion is completed. remember you should relat this method of digestion by your method and estimate how much acids you need to digest .
Hi my Friend! Working withHClO4 is eztremely dangarous! You must be careful because of risk for explosions. Warming must use a kind of temperatur program. More later! Take care please!
45 years with perchloric acid without accident
Control of temperature of bath or Al-block surrounding the reaction flask (tube) is obligatory.
Never place the reaction mixture directly on a heating plate!!!
All wet ashing is performed in ventilated hood with strong exhaust
TEN rules of work by using perchloric acid
1. Wet ashing program should worked out for every material (matrix) and acid mixture
2. Start with an experimental model
3. To max. 1 g biological material (dry weight) add 15 ml HNO3/HClO4 = 7/3
4. containing not more than 500 mg fat
5. Add always a previously prepared mixture of acids to the samples.
Notice the total volume by a pen.
6. Avoid sudden bump cooking by the use of boiling pins or thoroughly rinsed boiling stones
7. Digest at room temperature a few hours. (Over night) Solubilisation of fats at 132° C.
8. Follow the decrease of total volume and add more HNO3 if necessary
9. If getting dark, an indication of the nature, break off the ashing process!
10.Control the colour at 180° C before heating to 225° C..
Mr. Heravi, thanks for your input. I agree with Dr. Frank that using HClO4 is dangerous. I will follow your methods and remember to keep them in mind whenever I ash/digest my samples.
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