Trace2O AquaSafe WSL25 Plus, Instruction Manual

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SECTION 2: PREPARING BACTERIOLOGICAL MEDIA IN A LABORATORY
FACILITY
Membrane Lauryl Sulfate Broth:
For 50 tests, dissolve 7.62g of Membrane Lauryl Sulfate
Broth (one sachet) in 100mL deionised water.
The broth is supplied in a pre-weighed sterile sachet, with indicating silica gel that will turn
from orange to green, to indicate moisture penetration.
Tear open the sachet and remove the silica gel with the forceps. If the silica gel is green,
discard the sachet without using.
Pour the entire contents of the sachet into 100mL of deionised water.
Gently heat the mixture to ensure that the powder is fully dissolved, but do not boil.
After ensuring that the 125mL plastic bottles provided contain no residues of previous MLSB
or cleansing agent, pour the prepared medium carefully into the bottles.
Replace bottle lids but leave them slightly loose - do not fully tighten.
Sterilise in an autoclave at 121°C for 10 minutes, or place bottles in a pressure cooker and
maintain in steam at pressure for 15 minutes. Remove the bottles, allow them to cool to room
temperature, fully tighten the tops and then store in a cool, dark place.
When the media has cooled to room temperature, pour sufficient MLSB (2mL) onto each
membrane pad to saturate the pad.
When the pad is fully saturated, decant any excess MLSB as waste
Media Ampoules: Media Ampoules are pre-sterilised ampoules containing 2 mL of dissolved
media. They have the advantage of convenience and of always being sterile. These
ampoules are available for Faecal Coliform Counts (pack of 50) and Total Coliform Counts
(pack of 50). Simply unscrew the cap, pour the media onto the pad and discard the empty
ampoule.