H2S Kit Preparation

Need of Project: To reduce the cost of H2S Strip Test Kit.

What is the H2S Strip Test?

H2S test performs to check the microbial contamination in water. H2S is produced if the sulfur compound is reduced by the bacterial strain. It shows that the microbe reduces sulfur-containing compounds to sulfides during this process.  

Chemicals to prepare H2S bottles

Bacteriological peptone                                                                        40.0g

Dipotassium hydrogen phosphate                                                         3.0g

Ferric ammonium citrate                                                                         1.5g

Sodium thiosulphate                                                                                 2.0g

Liquid detergent                                                                                      2.0ml

Water                                                                                                   100.0ml

We need to find Water holding Capacity of the different papers to select the paper type for the strips

The procedure of the H2S Strip Test?

Step-1: Clean the glassware. 

Step-2: Dissolve above mentioned chemicals in Distilled water or in tap water.

Step-3: Take absorbent paper, place a measured quantity of media on it. (Each paper strip for a 10 ml test sample needs to contain 0.5 ml of media.)

Step-4: Dry the paper strips at 55 degrees Celsius. After drying, store it in a dry container.

Step-5: While using strips keep it in the sterilized container and add the sample.

Expected Results of this test

The blackening of samples denotes the presence of H2S.

How to use H2S strips?

Step1: Autoclave the test tube and dry it completely.

Step2: Keep the stored H2S strips in the test tube.

Step3: Add a 5ml water sample to the test tube and cover the opening of the tube.

Step4: Observe the tubes after 48 hrs and not the observations as written above.

Costing of the H2S bottle:

Sr. No.	Chemicals	Quantity of Chemicals Used in gm	Cost/100ml water	Cost/Bottle 500gm
1	Di Potassium Hydrogen Phosphate	3	0.58 Rs	97 Rs
2	Bacteriological Peptone	40	118.96 Rs	1487 Rs
3	Ferric Ammonium Citrate	1.5	1.84 Rs	614 Rs
4	Sodium Thiosulphate	2	1.36 Rs	340 Rs
5	Liquid Detergent	2 ml	0.32 Rs	80 Rs

Sr. No.	Other Materials	Quantity	Cost/120 bottles
1	Filter Paper	2 A3 Size Papers	4 Rs
2	Electricity for Oven	2KW for 2Hrs	40 Rs
3	Cost of Bottle	120 bottles	480 Rs
4	Cost of 1 Sticker	120 Stickers	89 Rs
5	Labour Charge (25% of the material used)	2 Days	368 Rs

Manufacture cost per bottle is 9.20 Rs

Trials of H2S Kit:

For the testing of kit we had taken the water samples from Grey water, Vigyan Ashram Kitchen, Dream House, Tap water, UV filter

Observation Chart of Trial tests:

First Set of Experiment :

Second Set of Experiment :

From the above table we can say that our H2S Kit is showing Dissimilar results for UV filter.

References:

1.       THE HYDROGEN SULPHIDE PAPER-STRIP TEST, Luke M. Mosley & Donald S. Sharp (February 2005)

2. H2S PAPER STRIP METHOD – A BACTERIOLOGICAL TEST FOR FAECAL COLIFORMS IN DRINKING WATER AT VARIOUS TEMPERATURES J. Pillai, K. Mathew, R. Gibbs, and G. E. Ho.