23 Fabruary 2025
Introduction :-
The H₂S water testing kit is a simple method to detect the presence of harmful bacteria in drinking water. It identifies bacterial contamination by detecting hydrogen sulfide (H₂S) gas produced by certain bacteria, indicated by a color change—usually turning black in contaminated samples.
Materials :-
| Forecep |
| Petri plate |
| Filter paper |
| Beaker |
| Plastic bottle |
Preparation of media for 200 H2S kit strip :-
| Chemicals | Quantity |
| Bacteriological grade peptone | 80gm |
| Dipotassium hydrogen phosphate | 6.0gm |
| Ferric ammonium nitrate | 3.0gm |
| Sodium thiosulphate | 4.0gm |
| L – cysteine HCl | 0.5gm |
| Liquid soap | 4.0ml |
| Distilled water | 200ml |
• Measure 200 ml of distilled water into a glass beaker, then add and dissolve the chemical.
• Stir until powder media is completely soluble in water.
• Cut the filter paper into pieces of 8 × 2.5 cm to make 200 strips.
Check pH :- pH should be maintained between 6.5 to 7.2.
Sterilization process :-
- Clean the glasswares such as forecep, petri plate etc.
- Autoclave the media, forecep, filter paper at 121°C for 15-20 minutes.
- After autoclaving, remove the media, filter paper and glasswares from sterilizer and place them in laminar air flow.
- Take 30 ml new 200 plastic bottles.
- Open the caps of bottle and keep in hot air oven at 55-60°C for 20 minutes.
- Sterile the bottles using Laminar Air Flow for 1 hrs.It helps to prevent Bacterial contamination.
Methodology :-
- Dip all the strips in the given media, then fold each strip using forceps and place them in a sterile Petri plate.
2. Use a hot air oven to dry the strips at 50°C for 40 minutes.
3. After that, place the strips in the laminar airflow cabinet for sterilization for 10 minutes.
4. The strips were then stored in a dry, sterilized plastic bottle.
5. One bottle was filled with tap water and the other with distilled water, and they will be kept for 48 hours. The bottle with tap water showed a black coloration, whereas the distilled water bottle showed no color change, retaining the original media color.
26 Fabruary 2025
Result :-
| Sample | Time | Result |
| Tap water | 48 hours | Positive |
| Distilled water | 48 hours | Negative |
