By chemville on Thursday, April 22, 2004 - 03:56 pm:
I need to know the difference between the two. We both use them in our HPLC. Can anyone tell me the difference in application and its parameters. Thank you.
By Anonymous on Thursday, April 22, 2004 - 05:22 pm:
Although I dont really understand the true nature of your question, I'll do my best. The DAD is an Agilent product while the PDA (996/2996) are Waters products. Other companies may also use the DAD/PDA acronyms as well, I dont think they are trademarked. Both do the same job in a similar manner although there are differences in the design and software. The 2 biggest differences that would affect a user is the use of a reference wavelength (used to account for RI effects) and the variable slit width on the DAD. The PDA does not need a reference wavelength due to its cell design and has a fixed slit width. The slit width on the DAD is used to account for lowering lamp energy with time. The PDA uses a lamp normalization routine instead.
By Alex on Friday, April 23, 2004 - 06:20 am:
Hi chemville.
What are the differences from the practical point of view. Do you see any differences in the results?
up to now I thougt DAD and PDA to be synonyms of (Photo)Diode Arraray (Detector)
By DR on Friday, April 23, 2004 - 08:18 am:
They are synonyms - there is the same type of vendor to vendor variation among Diode Array detectors as you find among UV/VIS detectors, compounded by software issues. Waters/Agilent are discussed above. Thermo uses a 5cm flow cell and their own software to get a very high S/N ratios. Hardware from Shimadzu, PE and Dionex is a little different from the above too. You really have to evaluate diode array systems as a package.