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Experiment Sharing:Microwave Digestion of Fish Oil

Microwave digestion technology is widely used in food, metallurgical samples, biological samples and other fields which digest samples completely and is conducive to further chemical analysis. Welso sorted out a microwave digestion method for fish oil samples.

Fish Oil

Fish oil capsules are capsules made of gelatin-encapsulated health products, which are partially degraded from collagen in animal skin, bones, muscle membranes and other tissues. Usually it is white, pale yellow translucent micro-shiny flakes or powder particles. In the process of microwave digestion, such samples are prone to explosion-like pressure surges, commonly known as "burst vessels". Welso offers a safe and effective method to improve the safety and efficiency of gelatin-based samples during microwave digestion.

Sample name: Fish oil softgel

Reagents: Nitric acid 65%, AR; Hydrogen peroxide 30%, AR

Instrument: WMD600 microwave digestion system

WMD600 microwave digestion system

Numbers of Samples: 10

Digestion Procedures:

1. Take 1 fish oil softgel (about 1.0g) and place it at the bottom of each inner vessel.

2. Add 5ml of hydrogen peroxide and gently shake the vessel to prevent the capsule from sticking to the bottom.

3. Place the inner vessels into a fume hood and pre-digest it for about 10 minutes. During this period, it is necessary to gently shake the vessel from time to time to soften the softgel.

4. After pre-digestion, wait solution cooling down to room temperature and add 8ml nitric acid. Mix them gently.

Note: Do not add concentrated nitric acid until the pre-digestion completes and cool down to room temperature, otherwise the sample will become foam and pour from the vessel.

5. Seal the vessel and load it into the digestion system for digestion.

Program As Followed:













Temp. Increase Time(s)




Temp. Decrese Time(s)




6、After digestion and cooling down, transfer digestion vessels into fume hood and wait for 10 minutes.

7、Unscrew outer vessels one by one and release pressure. Take out of the inner vessel, and put inner vessels into heating blocks to dry.

8、Transfer rest solution to volumetric flask, rinse vessel cap and walls.

9、Add to constant volume until digestion solution cooling down and wait for analysis.

Note: Above digestion uses hydrogen peroxide to digest. Also, it is possible to use nitric acid to digest, method as following:

Add 5mL nitric acid, and pre-digest at 120℃( solution turns clear or there is no brown gas, usually no less than 20 mins). Then add 2mL nitric acid, 1mL pure water and mix them. Seal the vessels and then digest.

WMD600 Which Ensures Safety

Welso WMD600 microwave digestion system uses non-contact all vessel scanning pressure control system. It monitors each vessel in real time. Once pressure is over, the system will stop immediately to protect the vessels.


Press-release Ring and Hole Design

Press-release Ring and Hole Design

Press-Release Ring And Hole Design

Each digestion vessel passed digestion pressure resistance test. There is no obvious deformation and damage and is still in good working condition after intensive experiments.

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