Purpose

To describe the preparation of 25X Phosphate Buffered Saline-0.05% Tween 20 (PBS-Tween 20) for use in ELISA assays.

References

None

Materials

  • RMS-104 Sodium Phosphate Monobasic, Monohydrate
  • RMS-105 Sodium Phosphate Dibasic, Anhydrous
  • RMS-106 Sodium Chloride
  • RMS-107 Tween 20
  • RMS-108 Thimerosal

Equipment

  • Appropriately sized clean container
  • Stir plate and stir bar
  • Weigh Boats
  • Balance
  • pH Meter
  • pH Standards (pH 4 and pH 7)
  • Pipet and pipet bulb
  • Appropriately sized graduated cylinder

 

Procedure

  1. Per liter of 25X PBS-Tween 20 to be made, measure the following:

         - 6.5 g Sodium Phosphate Monobasic, monohydrate

         - 28.75 g Sodium Phosphate Dibasic, anhydrous

         - 225 g Sodium Chloride

         - 12.5 ml Tween 20

         - 0.1 g Thimerosal

  2. Place the measured components into a container appropriate for the batch size.

  3. Per liter of 25X PBS-Tween 20 to be made, add 950 ml deionized water to the container.

  4. Add a stir bar, place container on stir plate and stir for approximately four hours at room temperature until all solids are dissolved.

  5. Standardize pH meter at pH 4 and pH 7.

  6. Measure pH of 25X PBS-Tween 20 while stirring. pH should be pH 6.0 - 6.2.

  7. Place in closed container and label with contents, date and batch number.

  8. Store at room temperature up to one year.