Bacteriological H2S field tst kit,bottle

General Description:
Bacteriological field testing kit for drinking water using H2S test medium

Technical Specifications:
This is a simple bacteriological testing kit that could be used to indicate the presence of pathogens. It does not attempt to identify the pathogens.
The kit can be used with any water irrespective of its source, including chlorinated water.
The kit comprises a simple sterilized plastic or glass bottle that contains dry powder medium. The powder is completely soluble in water and a dark amber colour solution is formed on the addition of water.
The solution will change colour to black in the presence of H2S producing organisms in ambient temperatures between 25ºC and 44ºC, preferably to be kept at 35-37ºC, for an observation time of 24 to 48 hours. No incubator is needed for this range of temperatures.

The medium
The composition of the medium powder is as follows:
Bacteriological grade Peptone (IP/USP/BP) 20.00 gm
Dipotassium Hydrogen Phosphate, A.R. 1.50 gm
Ferric Ammonium Citrate (Brown) (IP) 0.75 gm
Sodium Thiosulphate, A.R. 1.00 gm
L-Cysteine HCl 0.125gm
Teepol or Labolene (neutral pH) 1.00 gm
Total 24.375gm

The dry medium is in the form of brown to yellow homogeneous free flowing powder, or soaked in rolled filter paper and dried.
The pH of the aqueous solution with distilled water ranges between 6.5 and 7.2 at 25ºC.
The powder must be prepared according to Good Manufacturing Process (GMP).

The bottle
The bottle is a transparent screw-capped neutral glass of 30ml capacity without any crack or air bubbles and spotless surface. The glass bottle should withstand dry heat at 150ºC for three hours or steam at 130ºC at 20lb pressure for 30 minutes. The bottle should be marked at the 20ml. level.
The bottle has a plastic cap that fits the bottle exactly with a rubber washer to prevent leakage. The cap and washer must withstand autoclave temperature of 121ºC for 30 minutes.

The preparation
The bottles and caps are autoclaved at 121ºC for 15 minutes with caps loosely fitted. The amount of powder (490 mg) is dispensed in the sterilized bottles maintaining the GMP. The dispensation of the medium into the bottle should be done under dehumidified conditions.
The caps of the bottles are tightened in a laminar air cabinet. The capped bottle should be shrink-packed to eliminate any risk of moisture ingress during the transportation and storage.

Packaging and labelling:
Each bottle should be labeled or printed with permanent ink (which should withstand the 121ºC temperature for 30 minutes) at the 20 ml mark. Each bottle should be labeled with the name of the product, directions for use, name and address of the manufacturer, batch and code number, manufacturing and expiry dates and storage conditions.
Each 10 bottles should be packed in 5 ply corrugated carton box with label on the outer surface having similar information as mentioned above for the bottles. An additional user instructions sheet should be provided for the 10 bottles pack.
Suitable number of the 10 bottle carton boxes shall be placed in 7-ply tar coated main water-proof corrugated box marked with the name of the manufacturer, batch number and the manufacture and expiry dates.

Instructions for use:
The test is not to replace the conventional Presumptive Coliform test and other laboratory based tests, and the results should be treated with caution.
Problems that are likely to be encountered with these kits are false positive rather than false negative. In groundwater, there is a possibility of sulphides being present and giving positive results of H2S rather than the faecal contamination. Such misclassification of drinking water errs on the side of safety.
The kit is useful in educational and motivational campaigns to promote water sanitation and hygiene in outreach and dissemination programs.
The kit is used in regions where the ambient temperature ranges between 25ºC and 44ºC. The optimal incubation temperature would be 35-37ºC. The sample should be kept 24-48 hours where after it can be observed for potential colour change.
In cold climatic regions (where ambient temperature is below
25ºC) the kit should be used with an incubator.
The kits in their boxes should be stored in cool, dry place away from sunlight at room temperature of maximum 30ºC.
SHELF LIFE should be considered when ordering, since it is relatively short for the powder based kits. Whether shelf life of 12 months is acceptable, or 24 months is required should be specified when ordering. If longer shelf life is to be considered, CO should contact TF/WSE-Center at Supply Division before ordering.
The kit could be used in routine testing of water quality as well as during epidemics of water borne diseases to find the source and spread of pollution.