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SPE Separation with a Vacuum Manifold.
Posted: Mon Jan 26, 2009 9:12 pm
by John R. Carver
I am currently using a 12-port SPE vacuum manifold. This is very time consuming to manually adjust the flow rate. Does anyone know of a semi-automatic or automatic system that will produce a constant flow rate?
Posted: Mon Jan 26, 2009 11:40 pm
by Uwe Neue
I assume that you adjust the flow with a vacuum gauge and a throttling valve. Once it is set, it should work for subsequent applications, right?
Posted: Tue Jan 27, 2009 8:11 am
by Spuzzin
Uwe,
From my experience of SPE this isn't the case. The density of the packing varies from cartridge to cartridge which has an effect on the flow rate as does the amount of particulate being drawn from the samples.
John,
I don't know of any automatic methods for this. I agree that it is a very time consuming process.
Rich
Posted: Tue Jan 27, 2009 8:38 am
by HW Mueller
We put a little faucet (Luer lock connections) on each cartridge to regulate them individually. There are metal as well as plastic versions available, I don´t remember from where we got them, but I seem to remeber that the plastic versions have a tendency to bind (get stuck). SPE manifolds were used extensively for RIA and ELISA.
Posted: Tue Jan 27, 2009 6:26 pm
by dr_Pyrex
It's two well known (and working well) "automatic" SPE systems :
1. Gilson - GX 271 ASPEC
http://www.gilson.com/Products/product.asp?pID=281
GX 274 ASPEC
http://www.gilson.com/Products/product.asp?pID=282
2. Caliper
Rapid Trace SPE Workstation
http://www.caliperls.com/products/rapid ... tation.htm
We use old Gilson system. Constant flow rate is obtain by air pressure from the needle. You can easy create you own methods with different parameters like flow rate, time of drying, time of loading of the sample etc. by software controlled the system.
Both system are quite expensive and (in my opinion) it is reasonable to use it only with high number of samples.
Posted: Tue Jan 27, 2009 7:44 pm
by adam
Some vendors sell SPE cartridges where you can push the liquid through with a syringe, instead of using the approach of pressurizing to push the liquid.
I have to admit that I have never tried this, but it sounds like a good option if you are doing something like 7 or 8 samples at a time. For situations where you have 40 samples at a shot (or more) the pressurized manifold is probably the better way to go.
Posted: Tue Jan 27, 2009 7:45 pm
by adam
To clarify: push through with a syringe piston.
Re: SPE Separation with a Vacuum Manifold.
Posted: Wed Jan 28, 2009 1:02 am
by Pragmatist3
I am currently using a 12-port SPE vacuum manifold. This is very time consuming to manually adjust the flow rate. Does anyone know of a semi-automatic or automatic system that will produce a constant flow rate?
You must have individual valves for each column and manually close off those columns that drain slightly quicker. I don't know how you could possibly have something "automatic" to shut off a particular column until it runs dry and then it's too late. I use a 24 port all the time but usually limit the number of samples to one side of twelve and pay attention.
Stopcocks for SPE flow control
Posted: Tue Feb 10, 2009 2:21 pm
by Tom Waeghe