What should I do if there are crystals in the concentrated wash solution? ( 4 July 2013 )

Warm and agitate the solution until all crystals are dissolved, and then prepare the 1X solution.

Will the sterility or the quality of the water used to reconstitute the wash solution affect test results? ( )

We recommend using water which is distilled or purified by reverse osmosis or a system such as MilliQ or Elga, which reduces the amount of bacteria in the water.
It is not necessary to use sterile water, or to store the distilled water in a sterile environment.
While the 1X wash solution will not be sterile in these conditions, its low level of bacteria will not affect results.

A high level of bacteria in the water, however, caused by the progressive contamination of the wash solution or the use of dirty glassware, can lower the quality of the test.

In this case, you will notice a reduction in the difference between the positive and negative signals, and an increase in the background signal.

Generally, it is recommended that the 1X wash solution be prepared at the beginning of the week, and not be kept for more than 5 days (ex. from Monday to Friday).
When making new 1X solution, it is important to wash the glassware and to rinse the wash system (manual or automatic).

What recommendations can you make to optimize the washing steps? ( )

The washing system plays an important role in the quality of the final results:

  • Fill the wells completely at each wash (300µl).
  • Tap hard after the last wash to remove all fluid.
  • Avoid drying of wells between washings. 
  • Do not scrape the bottom of the wells during the washing steps, which could remove the antigen/antibody complexes.
  • If using a manual wash method, overflowing of wells is not a problem. However, after the first wash it is important to empty the wells quickly to avoid contamination between wells.
  • The cleanliness of the wash system may affect the quality of the results. Bacterial contamination of a tube or pump may arise if the system is never washed. We suggest that you pay particular attention to the cleanliness of the washing apparatus, regularly decontaminating the washer with a suitable detergent.

What type of washing system should I use? ( )

All available washing methods are compatible with IDvet kits:

  • squeeze bottle
  • pipette
  • manual comb system
  • automatic washers

We suggest that you validate the internal washing system before testing high sample numbers.

Generally, systems which increase the contact time between the wash solution and the plate increase washing efficiency.

It is possible to include a soaking time between two steps (serum and conjugate or conjugate and substrate). Generally, the quality of the wash step is equivalent, or increased, with a soaking step. This observation is particularly true for milk tests, where the perfect dissolution of fat may require increased contact time between the wash solution and the plate.