Dip Slides are used to determine the total aerobic microbial contamination in aqueous (water) samples or on surfaces. Using them on non aqueous samples such as fuel or oil will lead to erratic results at best.
Dip Slides consists of a plastic slide carrying two different nutritive agar gels on opposite sides of the slide. One side has been designed to culture bacteria which grow as visible discrete red colonies when the slide is incubated for a few days. The other side of the slide will culture moulds (fuzzy or fluffy colonies) and yeast’s (usually white, cream or pink round colonies). The slide is dipped into the fluid to be tested or pressed against a surface, and then incubated. The slide appearance is compared to calibration charts.
Full instructions are supplied and no special training is required to use a Dip Slide. A warm dark place is needed for incubating a Dip Slide but for consistency, particularly if the ambient temperature fluctuates, a small incubator is preferable.
The Dip Slide technology was designed to test aqueous samples. It can also be used to test surfaces and instruction leaflets have calibration charts for surfaces. The Dip Slide technology works because a specific amount of water (approx 1/50 of a millilitre ) will be adsorbed onto the surface of the slide when it is dipped into water. Other aqueous fluids are often tested using Dip Slides but the actual amount of fluid that is adsorbed onto the slide will probably vary from fluid to fluid; hence Dip Slides may require re-calibrating for each fluid type tested. If a non-aqueous sample is tested, e.g. Fuel, the amount of sample that will be adsorbed onto the slide is not known. The MicrobMonitor2 test has been designed to test non-aqueous samples.