How to decrease file size with Waters 2996 PDA?

Discussions about HPLC, CE, TLC, SFC, and other "liquid phase" separation techniques.

8 posts Page 1 of 1
Maybe a bizarre problem, but here goes. We got a PDA detector over the summer and now our computer's hard drive is full. I'm currently doing a 15 min run with a gradient of 5-95% ACN over that period. Each run takes up 700 MB! I could get away with just a UV detector, but now we have the PDA so I've got to figure out how to make this work. I've been looking for a way to decrease the raw data file size, but increasing the resolution (1.2 to either 2.4 or 3.6 nm) and decreasing the sampling rate (1 to 0.5 sample/sec) haven't helped. I'm trying to find something online or in the user manual but am coming up empty. Any suggestions?
Dr Zoidberg wrote:
Maybe a bizarre problem, but here goes. We got a PDA detector over the summer and now our computer's hard drive is full. I'm currently doing a 15 min run with a gradient of 5-95% ACN over that period. Each run takes up 700 MB! I could get away with just a UV detector, but now we have the PDA so I've got to figure out how to make this work. I've been looking for a way to decrease the raw data file size, but increasing the resolution (1.2 to either 2.4 or 3.6 nm) and decreasing the sampling rate (1 to 0.5 sample/sec) haven't helped. I'm trying to find something online or in the user manual but am coming up empty. Any suggestions?


Change Method Instrument. Uncheck "spectra".
You could also try compression software, if you decide you do want the spectral data. Zip is generally the most common, but I find .RAR (Winrar, the free download says it's a trial, but it really never stops working) to be superior in some situations. If you have a fast processor, select "Best" under compression method. I imagine your chromatography software probably doesn't apply any compression to the collected data, so you should be able to get some decent compression ratios.
On another note, hard drives are dirt cheap nowadays, with the increasing popularity of SSD's. A 2 terabyte internal hard drive can be had for around $50 before shipping. You'd be able to fit a few thousand chromatograms on one before compression.
Higher sampling rates, max resolution, huge wavelength range all lead to huge files for spectral data. Waters' defaults all tend to be too big/fast/narrow vs what's actually needed. You probably don't need 3d for your entire run either.
Thanks,
DR
Image
I'm not familiar with that software but does it allow you to take a spectrum at each peak apex? That was the old way to keep the file size down on my old PE system.
Thanks for the suggestions. I've been looking into buying a new large capacity hard drive as it seems like the best long term solution.

DR; I don't have the option to change from 3D to 2D, from what I've seen that's the 2998 detector.

Steve; I wish I knew the answer to that. I've been trying to dig through the software for ways to minimize the amount of spectra taken, but have come up empty. I wouldn't even know where to start looking for your suggestion.
In the instrumnet method you can select 2D data collection. Yuo can use as a ( channel UV detector
Good Evening,

Are you limiting the range of wavelengths in your scans? If you're not looking to acquire a spectrum or spectra, all you would need do is to set the wavelength range to a factor of 10 times the bandwidth. So at 1.2 nm resolution, for example, the minimum acceptable wavelength range would be 12 nm, or at 4.8 nm bandwidth, the minimum acceptable wavelength range would be 48 nm.

Also, you can minimize the data acquisition rate to include 15-20 data "points" (meaning spectral acquisitions) across the smallest peak of interest in your chromatograms.

Hopefully these will help your file size issue a bit. Best wishes!
MattM
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