Magnesium is an essential mineral found naturally in fish and plays an important role in human nutrition. Determining the magnesium content of dried fish helps evaluate its nutritional value, ensure product quality, and verify compliance with food quality standards.
We have taken dry fish(Bombay Duck/Lote Fish) sample for this test.
Glassware used in Magnesium Testing Of Dry Fish Sample:
Equipment Used
- Beakers (100 ml) – For sample extraction.
- Silica Crucible(30 ml capacity) -To hold the sample.
- Volumetric Flasks (100 ml, 1000 ml) – For standard and sample dilution.
- Pipettes (5 ml) – For transferring reagent & standard solutions.
- Glass Funnel & Filter Paper Watman No. 42 – Used for filtration purpose.
- Hot -plate – To boil the sample.
Chemicals Used
- Ethylenediaminetetraacetic acid(EDTA) Solution (0.01 M)– Complexing agent that reacts with Ca²⁺ and Mg²⁺ ions. EDTA binds with Ca²⁺ and Mg²⁺, breaking the indicator-metal complex.Preparation described previously.
- EBT indicator- Ca & Mg ions are complexed by EDTA, the free EBT turns blue, indicating the endpoint.
- Patton & Reeder Indicator– Forms a wine-red complex with Ca²⁺ and Mg²⁺, signaling that all hardness-causing ions have been complexed by EDTA. Here we have used all the following chemicals/reagents of Researchlab company. You can use the same company or any other companies.
- 40% sodium hydroxide solution-Adjusts pH for accurate titration. Preparation described previously
- Distilled Water –To make the titrant. The conductivity of distilled water should be <5 μS/cm to prevent contamination
- Hydrochloric acid (HCl) – Dissolves ash and maintains acidic medium for complex formation.
- Nitric acid (HNO₃) – Oxidizes organic matter and converts iron into soluble ferric form during digestion.
Method for Testing Of Magnesium in Dry Fish :
| Step | Process | Calculation |
| Calcium Hardness Testing | 1. Weigh desired of dry fish sample.Ignite it into muffle furnace to make it ash (Process previously described) .Add 50–100 ml of distilled water ,5 ml HCl & 5 ml HNO3, boil gently. 2.Filter it through filter paper.Volume make up to 250 ml. 3. Take 100 ml of the water sample into a 250 ml conical flask.Add Titration as total hardness. Procedure described previously. 4.Ca hardness procedure described previously. | Note the burette reading (ml of EDTA used) at the endpoint.Use the formula Calcium Hardness (as CaCO₃ in mg/L) = (Volume of EDTA(V1) × 100 x 1000 × Strength of EDTA) / Sample Volume (V) |
| Magnesium Hardness Testing | After doing the ca hardness calculate the Magnesium Hardness. | Magnesium hardness=(Total Hardness – Calcium Hardness) |
| Magnesium Calculation | Magnesium(%)=(Magnesium hardness x 0.024312 X100X DF )/ Sample taken |
Importance of Magnesium Testing in Dry Fish :
- Determines the nutritional value of dried fish & Supports correct nutritional labeling.
- Measures the magnesium content accurately.
- Ensures product quality and consistency.
- Helps meet food safety and quality standards.
- Assists in quality control during processing.
- Detects variations in mineral content.
- Provides reliable information for consumers.
- Increases consumer confidence in the product.
Handling Mistakes During Magnesium Test of Dry Fish :
- Using contaminated glassware or equipment.Proper cleaning Process described previously.
- Weighing the sample inaccurately.
- Adding the wrong amount of acid during digestion.
- Incomplete digestion of the sample.
- Incorrect labeling or recording of samples and results.
- Poor mixing of the sample solution before analysis.
Conclusion:
Magnesium testing of dried fish is an important analysis for determining the nutritional quality. Accurate sample preparation, proper digestion, and correct instrument calibration help ensure reliable results. The test supports quality control, nutritional labeling, and compliance with food quality standards, ensuring that consumers receive safe and nutritious dried fish products.To perform magnesium test at manufacturing company or laboratory should ensure by following standard procedures mentioned above to accurately determine the iron and assess the quality of any feed with availability of the apparatus & chemicals and also the above real-time photo attachment will help to understand the testing process completely. In addition, if expert guidance is needed ,please reach out to ProResearch & Testing Laboratory
FAQ Related to Magnessium Testing of Dry Fish:
What is the purpose of sample digestion before titration?
Acid digestion dissolves the fish tissue and releases magnesium into solution by removing the organic matrix.
What is the principle of the EDTA titration method for magnesium determination?
The method is based on the formation of a stable 1:1 complex between magnesium ions (Mg²⁺) and EDTA (ethylenediaminetetraacetic acid). The endpoint is detected using a suitable metal ion indicator at an appropriate pH.EDTA is a strong chelating agent that forms stable complexes with magnesium ions, allowing accurate quantitative determination.
Why is pH adjustment necessary before EDTA titration?
The pH is adjusted to about 10 using an ammonia-ammonium chloride buffer because magnesium forms a stable complex with EDTA under alkaline conditions.
Which indicator is used in the EDTA titration of magnesium?
Eriochrome Black T (EBT) is the most commonly used indicator. It forms a wine-red complex with magnesium, which changes to blue at the endpoint.
What is the endpoint of the titration?
The endpoint is indicated by a color change from wine red to pure blue.
What precautions should be taken?
Use clean glassware,measure reagents accurately,handle concentrated acid carefully.
How We Verified This Testing/Research Procedure :
This testing is done under qualified analysts in our lab.Continually monitored by expertise.Repeatedly testing is always done to get accurate result.
Written by
Riya Ghosh (M.Sc. Food Technology, MAKAUT)
Designation – Chemist
Reviewed by
Anwesha Das (M.Sc Microbiology,BU)
Designation – Microbiologist
Verified By
Dr. Jyotirmoy Kumar Dey (Phd,Chemistry)
Designation – Senior/Chief Chemist
Experience – 25 Years +