avatar: Klund
1 posts
Replied to Klund's post on April 23rd, 2018

We have purchased a Rheodyne 9725 injection valve for use in our system, but we would like to use a PEEK injection needle which requires a  16 gauge injection port size.  I have been looking at the 3725 model (with modified injection port for 1/16" OD tubing), but it is rated for a flow rate of 10 to 800 mL/min.  Our application has a flow rate of < 1 mL/min. (usually 0.7 mL/min.).   Is it possible to purchase a model 9725 with a 16 gauge injection port?  Or is it okay to use the 3725 at a lower flow rate?  Could you please tell me what potential problems are associated with using the 3725 under flow conditions of < 1 mL/min.   Thank you for our advise,

Karen Lund 

avatar: chromatology
41 posts
Replied to Klund's post on April 23rd, 2018

Dear Karen,

The 3725 is a prep injector the internal diameter is bigger, you will get more diffusion and dilution of your peaks, this will translate in a lower plate count for your system.

Analytical injectors from Rheodyne uses a 22 gauge syringe This translates into a 0.413mm ID while a 16 gauge syringe is much bigger at 1.194mm ID.

Working under 1ml per minute means analytical flow rates and separations, I would then not advise using such a big needle and a prep injector, brand spreading will be very important destroying your resolution.