BASi
Bioanalytical System Inc.
BASi is a drug development firm providing contract research services and unique products for the pharmaceutical, biotechnology and medical device industries.
BASi Pollen-8 On-Line Injector
The BASi Pollen-8 On-Line Injector directs dialysate into the loop of an LC injection valve, which in turn loads samples sequentially into a liquid chromatograph at predetermined intervals. An on-line injector maintains sample order (no vials to drop or mix up) and saves both time and materials (no samples to manage, no vials to purchase). Injection frequency is determined by the time required to complete the chromatogram. In cases where the chromatography takes longer to complete than the time required to fill the loop, it may be necessary to overfill the loops until the chromatograph is ready for the next injection. Alternate injection and collection of samples in a fraction collector is another option during long chromatograms.
Capture All of the Dialysate
The Pollen-8 utilizes a 10-port injector with two injection loops. While one loop is filled with dialysate, the contents of the other are loaded onto the LC system. When the next interval begins, these loops reverse their roles so that dialysate is always flowing into one loop or the other. This type of approach makes it possible to "capture" all of the dialysate (if the loop is underloaded).
One Valve for Two Chromatographs
A 10-port valve also makes it possible to inject dialysate into two separate chromatographs. Both LC methods would have to monitor the targeted analyte directly, without pretreatment. For example, one LC would determine dopamine while the other LC was dedicated to acetylcholine analysis. Injection frequency would depend on the longer of the two chromatograms. Or, different loop sizes could be used for each side of the valve and the injection interval could be controlled by an appropriate external device.
One Chromatograph for Two Probes
The 10-port valve can also be configured so that two separate flow streams load into the valve and are alternately injected into the same chromatograph. This allows two microdialysis experiments to run simultaneously. The outflow from one probe would fill one loop while the outflow from the other probe would fill the second loop. Both probes could be placed in the same animal, as in a blood/brain barrier study. If the probes were in two separate animals, this approach could be used to study the response to different doses of the same drug.
One Now, One Later
When the 10-port valve is used with the BASi HoneyComb Fraction Collector it is possible to divide the dialysate between the injection loop and vials in the fraction collector. You can monitor one analyte on-line while collecting dialysate in a vial for later derivatization or analysis of other analytes such as amino acids or peptides. This approach also offers security by providing back-up samples in vials.
Microdialysis Probe Port
When the Pollen-8 is used as an on-line injector with a microdialysis system, the outlet tubing from the microdialysis probe is connected directly to the valve. This is best accomplished using a special fitting which grips the 0.65 mm OD Teflon or PEEK tubing without closing it. The same fitting can be used as a needle port to accommodate gas-tight syringes when injecting standards directly into the valve. It is lined with 1/16" OD Teflon tubing, flanged at one end. The long length of the Probe Port isolates it from fittings on the other valve ports.
Matched and Calibrated Loops
When sample loops on the Pollen-8 are overloaded and then injected onto the same LC system, it is useful to have them matched and calibrated. Otherwise, the peak height will differ when one loop is compared to the other due to differences in internal volume. For this reason, we offer sample loops as matched and calibrated pairs. Loops are purchased separately when the Pollen-8 is ordered.
Upgrade to Microbore
To change the valve from analytical to microbore operation, just purchase another valve and install it on the actuator. Changeover is quick and simple. Software in the Pollen-8 controller recognizes each valve and aligns the actuator accordingly. An additional waste port (MD-1265) and port connector (MD-1259) are required for use with microbore LC columns.
Place It Where You Need It
The valve and actuator are unbundled from the Pollen-8 controller to allow maximum flexibility when positioning the valve. You can stack the Pollen-8 controller in your BAS 480 liquid chromatograph while the valve rests on a bench top, inside a Faraday cage or column oven, or on top of an Awake Animal System. A 3.5 ft. (107 cm) cable connects the valve actuator to the Pollen-8 controller. The sole power cord attaches to the back panel of the controller.
Pollen-8 in Action
Current Separations feature 1 of Vol. 15 No. 2 details one experiment in which a Pollen-8 was used.