Ringer's Solution is used for the preparation of suspension of samples in bacteriological studies and for use as a diluent in dilution techniques for enumeration. Also used in the microbial control of apparatus by the rinse and swab method.

Approximate Formula:

Directions:

To prepare a 1/4-strength Ringer's Solution:

1.Take 1 piece of ampoule, shortly tap to ensure the granules are at the bottom.

2. Bend the upper part of the ampoule until it breaks open.

3. Suspend granules of 1 ampoule in 500ml of deionized or distilled water. Shake to dissolve the granules completely.

4. Sterilize in an autoclave at 121℃(15 lbs.) for 15 minutes.

5. The appearance of the solution is clear and colorless (after autoclave).

Principle and Interpretation:

1/4-strength Ringer's Solution is isotonic with bacteria and thus prevents them from being subjected to osmotic shock or from being osmotically damaged when they are removed from their customary environment. It is also more physiologically suitable for sensitive microorganisms than physiological saline.

Appearance:

Dehydrated medium is a free-flowing white granule. The prepared broth is a kind of colorless transparent liquid.

Precautions:

This medium is for laboratory use only. Dried medium which is past shelf life, caking or colour variation cannot be used.

Storage conditions and Shelf life:

Ringer ampoules for the preparation of Ringer's Solution must be stored tightly capped in the original container at 5-30°C. The dehydrated medium has a shelf life of 3 years from date of manufacturing. Prepared medium may be stored, out of direct light at 2-8°C.

Quality control:

Prepare the culture medium as per label directions. Inoculate cultures into test solution. At time zero (directly after inoculation) and after 45 minutes incubation at 20-25℃, subculture to TSA and incubate at 30-35°C for 18-24 hours. Determine colony counts at time zero and after 45 minutes.

References:

1. Ministry of Health (1937). Bacteriological tests for graded milk. Memo 139/Foods. London.

2. J.G. Davis, Laboratory Control of Dairy Plant, Dairy lndustries Ltd., London (1956)

3.Internationaler Milchwirtschaftsverband (1985). Zählung coliformer Bakterien in Milch und Milchprodukten (Internationaler Standard FIL-IDF 73).

4.Internationaler Milchwirtschaftsverband (1992). Milch und Milchprodukte – Vorbereitung der Untersuchungsproben und Herstellung der Verdünnungen für mikrobiologische Untersuchungen (Internationaler IMV-Standard 122).