M-Filter Rinse Broth

Composition**

**Formula adjusted, standardized to suit performance parameters

Directions

Suspend 9 grams in 1000 ml distilled water. Heat if necessary to dissolve the medium completely and sterilize by autoclaving at 15 lbs pressure (121°C) for 15 minutes. If desired add up to 9 g/litre of Polysorbate 80 and filter the broth medium before autoclaving.

Principle And Interpretation

The membrane filter technique is highly reproducible, can be used to test relatively large sample volumes and usually yields numerical results more rapidly than the multiple tube fermentation procedure. The membrane filter technique is extremely useful in monitoring drinking water and a variety of natural waters. M-Filter Rinse Broth complies with the formulation as described in USP (1). After membrane filtration it is often necessary to rinse the membrane filter in order to remove residues of liquid sample materials. Use of this medium is recommended if the sample contains higher hydrocarbons or fats.

The rinsing fluid protects the microorganisms retained by the filter from physiological shock, thus enabling microbes to grow rapidly. Polysorbate 80 emulsifies the carbohydrate and fats without harming the microorganisms. If the sample contains large quantities of carbohydrates or fats, additional quantities of polysorbate 80 upto 9.0 gm/litre can be added to the broth medium in accordance with USP recommendations.

After filtering the liquid sample, rinse the filter 3 times with 100 ml portions of the M-Filter Rinse Broth, then complete the test in usual way.

Quality Control

Appearance: Cream to yellow homogeneous free flowing powder

Colour and Clarity of prepared medium: Light yellow coloured clear solution forms in tubes

Reaction: Reaction of 0.9% w/v aqueous solution at 25°C. pH: 6.9±0.2

pH: 6.70-7.10

Cultural Response

M1323: Cultural characteristics observed after an incubation at 35-37°C for 18-24 hours.

Storage and Shelf Life

Store below 30°C in tightly closed container and the prepared medium at 2 - 8°C. Use before expiry date on the label.

Reference

1. The United States Pharmacopoeia, 2006, USP29/NF24. The united States Pharmacopoeial Convention, Rockville, MD.