Simultaneous Determination of Mineral Nutrients and Toxic Metals in M. stenopetala from Southern Ethiopia: A Comparative Study of Three Cultivating Areas Using MP-AES

Table 1

Optimization of acid mixture volume for the digestion of 0.5 g of leaf and seed samples at a constant temperature and digestion time.

Volume ratio (HNO3 : HClO4 : H2O2)	Total volume (mL)	Temp. (°C)	Digestion time (hrs)	Observations
2 : 1 : 1	4	300	3	Slightly green color
2.5 : 1 : 1	4.5	300	3	Slightly green color
3.5 : 1 : 1	5.5	300	3	Light yellow
4 : 1 : 1	5	300	3	Colorless and turbid
2.5 : 0.5 : 1	4	300	3	Colorless and turbid
2.5 : 0.75 : 1	4.25	300	3	Colorless with suspension
2.5 : 1 : 1	4.5	300	3	Colorless with suspension
2.5 : 1.25 : 1	4.75	300	3	Clear and colorless
2.5 : 0.75 : 0.5	3.75	300	3	Clear and colorless

The optimal acid mixture volume.