Mineral composition
Principle: Trace metals present in dried fish tissue are extracted through acid digestion using a tri-acid mixture (HNO₃:HClO₄:H₂SO₄) on a hot plate. The resulting clear solution is diluted and analyzed using ICP-MS (Inductively Coupled Plasma Mass Spectrometry), which enables ultra-trace detection and quantification of toxic metal elements such as mercury, lead, cadmium, and arsenic.
Procedure
1. Sample Digestion
- Weigh 1 g of dried, powdered fish sample into a digestion vessel.
- Add tri-acid mixture in a ratio of 10:4:1 (v/v):
- Nitric acid (HNO₃)
- Perchloric acid (HClO₄)
- Sulfuric acid (H₂SO₄)
- Heat the mixture on a hot plate at 130–200 °C until digestion is complete and the solution becomes clear.
2. Filtration and Dilution
- Allow the digested samples to cool.
- Filter using Whatman No. 42 filter paper to remove any particulates.
- Dilute the filtrate with Milli-Q water to a final volume of 50 mL.
ICP-MS Analysis
Instrument:
- Model: NexION 1000, PerkinElmer, USA
- Nebulizer: Meinhard
- Spray Chamber: Cyclonic type
Operating Conditions:
| Parameter | Setting |
| Plasma argon flow rate | 15 L/min |
| Auxiliary gas flow rate | 2 L/min |
| Nebulizer gas flow rate | 1.5 L/min |
| ICP RF power | 1600 W |
| Deflector voltage | 20 V |
| Ce⁺⁺/Ce⁺ (double-charged ratio) | 0.028 |
| CeO/Ce (oxide ratio) | 0.018 |
*The prepared solutions were made using Milli-Q water (resistivity: 18.2 MΩ·cm at 25 °C).
References
- Mohanty, B.P., Sankar, T.V., Ganguly, S., Mahanty, A., Anandan, R., Chakraborty, K., Paul, B.N., Sarma, D., Dayal, J.S., Mathew, S., Asha, K.K., Mitra, T., Karunakaran, D., Chanda, S., Shahi, N., Das, P., Das, P., Akhtar, M.S., Vijayagopal, P., Sridhar, N., 2016. Micronutrient composition of 35 food fishes from India and their significance in human nutrition. Biological Trace Element Research 174, 448-458.
- Das, B.K., Ganguly, S., Sarkar, D.J., Bayen, S., Dutta, S., Paul, S., Ray, A., Das Gupta, S., Roy, S., Chauhan, S.K., 2025. Toxic metal element concentration in 31 food Fishes from river Ganga: Risk assessment on human consumption. Biological Trace Element Research 203, 2339–2354 (2025).