Help on the selection of refractive index detector

[lu_pharm]

Hi,

We need to buy a used RID. Currently we can either have a HP 1047A or waters 401. I have no experience on them. I just heard that it will take very long time to get stable baseline for some RID. I knew both are old model. Regarding performance, whcih one is better? Thanks.

lu_pharm

[Rafael Chust]

I worked with the Waters RI 401 detector years ago and it seemed quite acceptable - at least taking into account how tricky these detectors are.

Nevertheless, I also used a Shodex RI detector (I do not remember the model) and it proved to be more stable than Waters, as the cell had a small thermostat that helped a lot keeping it stable.

From my experience and waht I have heard, Japanese products are generally better than American and European ones...

[AA]

The 401 is 4 generations old (401,410,2410,2414). I doubt that you could get support or parts (if needed) on a long ago discontinued peice of equipment. You should check of course if you are concerned about that kind of thing.

[ljc]

If these are older units, you'd have to test them side by side, since they probably don't perform as new and their original specs could be meaningless. The HP1047 is HUGE and heavy due to the T-stabilizing heat sink in it. The Waters unit is smaller (if it's the one I used, thought it was a 410) and wasn't as stable as the HP1047. But I recently aquired the new Agilent RI detector and it blows 'em both away in every aspect (except cost I guess).

If you don't need very high sensitivity, it might not matter much which used one you get, but the HP1047 does have many contact closures to remotely actuate purging, autozeroing, etc. However, zeroing it out with the adjustments is somewhat tricky. Be sure you get a manual with the HP if you buy it, or download it from Agilent's website, since it's not at all intuitive how to balance it out with all the buttons and knobs ! BTW, I have been told that the HP1047 was actually OEM'd by ERMA.

p.s. Have you considered ELSD instead of RI for your application ?

[lu_pharm]

Thank you for all your helps. I knew it is tricky for RID as RI is stongly affected by the change of environment that take long time to get stable baseline. As far as I know, many peoples are happy with the new HP RI detector. Anyway, we will take a try on 401 as we can have some warranty on it. Hopefully it works well. Thanks again.

[Oliver]

All I can say is we have a Shimadzu RID and it works nicely, i don't know of stabilisation problems. Later this year we may get a Waters RID as well, then maybe i can compare.

[Uwe Neue]

The 401 must be close to 30 years old. Nice age for a still functioning instrument.

Noise in RI is related to the stuff that goes into it, not the quality of the detector. You can do something about the noise by electronic smoothing, but this is a computational trick and has nothing to do with the detector itself.

[bob]

Just a note from a users point of view. If you take the 401 detector then this may help in the noise department. Connect about three feet of tubing to the exit port of the detector 0.01 or0.02 inch diamenter. Place the end into your waste solvent bottle. This will eliminate the potential for a pulse on the signal from the eluant exiting the detector. Also if temperature in your lab varies overnight then try sticking the column and detector into a styrafoam cooler to even out the temperature change. Tmeoerature variation plays havoc with RI detectors.--Lastly save some money and get a newer unit --Shimadzu is solid.

bob

[sudhis]

I worked on waters RI detector model 2414 and i found really no such problems . If base line not get stabilises for long check these
1.Column should be new , if its old you may take 2 to week long time for stabilisation.
2.There is option in detector, purge detector . You need to do this for quick results.

Hope it helps you.