The best is to make a test with only HNO3 in your beaker (few milliliters depending on the amount that you get) on a hot plate, then bring it to evaporation and add the solution used for your AAS analysis.

However, it coud be not sufficient especially for livers. You can try the following:

- 2 ml HNO3 (environ 2-3ml) on a beaker and an hot plate, evaporation ear dryness

- HCl + HNO3 on a closed beaker for one or two days (120°C)

if it still not sufficient you can add HF to HCL and HNO3, always on a hot plate and closed beaker for two days.

We would use a high pressure asher (HPA) from Anton Paar and use pure HNO3. Though a very expensive instrument, it is very efficient (280°C or even more), save and quick. In addition to low blanks you will not have any losses of analytes.

You have to determine either to use wet or dried tissue sample/s. Concentrated HNO3 (69%-70%) can be use to digest tissue sample, plus cheaper and easy to buy. Normally in our lab, we use about 0.5 to 1.0 gram of sample for 1 replicate. Sample will be placed in digestion vessel (tube / beaker). Afterwards,about 10mL of concentrated HNO3 (analytical grade, 69%) will be poured into the vessel. If possible, put a watch glass at the mouth of the vessel. Then, vessels will be placed on a digestion block or hot plate. Heating process should start at 40°C for 1 hour (to prevent vigorous reactions) and increase to 140°C for another 3 hours. Once the digestion completed (all tissue samples dissolved completely in the acid), all digested samples should be let to cool to room temperature. Ultrapurified / purified / distilled water should be added into the vessel to a fixed volume (advisable to 40 mL --> enough concentration for AAS detection most heavy metals). The samples should be then filtered by using filter papers (any brand but equivalent with Whatman No.1 grade). The filtrates can be stored (advisable in refrigerator: temperature at 4oC) until the metal determination AAS.

Dear Syaizwan. I am also working on trace element content in liver, muscle and gills of fishs. i have taken fish tissue, dried in hot air oven, then grinded it by mortar and pestle, then 1g of dried fish powder is used fro digstion by adding HNO3 on hot plate. Now I want to ask you Whether i should take fresh wet sample or dried one.plz help. 

Dear sir 

I want to know the procedure for drying fish sample on what temperature and how much time we have to dry the fish samples for trace metal analysis. I am confused now.

Thank you 

Dear sir

For wet tissue,HNO3 digestion is enough ?

Hello Adrian and Honey,

here is a method for heavy metal analysis in fish tissues in AAS that you could follow, they have used microwave digestion though, '1.0 g fish and 0.5 g feed samples were digested in teflon vessels with 10 ml HNO3 (65%):H2O2 (30%) (4:1) mixture in a microwave digestion unit (MARSXpress, CEM)'

For reference of this article; http://www.sciencedirect.com.ezp.sub.su.se/science/article/pii/S004896971731152X?via%3Dihub

Good Luck!

Arifin

Syaizwan Zahmir Zulkifli do you have refernce to method you menetioned

Microwave dig ester is a good option. ICP-MS is good for detailed ionic analysis,

Microwave digester