Hi, I need to remove air bubbles from a water sample before running it through a particle counter. I was wondering what common methods were available for removing air bubbles from oil samples so that they will not affect the particle count. I have looked into inline vacuum, and centrifugal; the inline vacuum looks like it uses a filter which would also block some particles, the centrifugal is only available for large volumes and I only need approx 3mL/min for small samples.

You can sparge helium through the water. The helium will carry away the dissolved oxygen and nitrogen, and the solubility of helium is extremely low in water. There shouldn't be any bubbles left behind. This is a common technique in HPLC where mobile phases need to be degassed prior to running into the instrument.

We use a small shop ultra sonic machine. The type used to clean small parts. The ultra sonic agitation will cause the air bubbles to rise to the surface where they pop. We used this method for our particle counter for several years and obtained almost identical results to the lab.

We removed the lid and held the sample bottle in the utlra sonic for a min. of one minute, depending on the viscocity of the oil.

We used to use ultrasonic agitation but found vacuuming the samples (in a vacuum chamber) to be the best.