It has been almost a month since you posted this question, it has had over 80 hits, and you have no replies. That’s not right. This forum is to simulate discussion. I would change your question to ask people to tell you about their tandem quadrupole rather than comparing so many different models.
I have a Varian 320 and its predecessor, the 1200. Both have been vey good rugged instruments with little down-time and do not require a great deal of maintenance to keep them running and producing good data. I have had the 320 less than a year and the 1200 over five years. The 1200 required the replacement of a PC board out of warranty which was quite expensive. Other than that we have had no problems. The 1200 has both ES and APCI sources and the 320 has only an ES source. I do not have the last generation ES source Varian introduced just before they became Agilent. I find the software very complete, easy to used and mature.
My concern about the 320 as an LC tandem quadrupole instrument is that it now belongs to Agilent, and I don’t believe Agilent will continue this instrument as a competitor to its already large selection of tandem quadrupoles.
I hear that the Agilent instruments are very good. There are a couple of different models of the tandem quadrupole and I am not sure what all the differences are. They just introduced a new model at ASMS last years. Agilent has been introducing a new software platform, Mass Hunter.
I understand that the API 5000 is very solid and has good sensitivity. There is also a model of it that has a linear QIT as the second MS stage which can be used as trap or are as a transmission quadrupole. I really know nothing about their software.
You should also look at the Waters tandem quadrupole. They two have several different models and introduced a new instrument at ASMS in Salt Lake City last year. Waters has very mature software and builds sound instruments.
The ne kid on the block is Shimadzu. The LCMS-8030 will make its U.S. début at PittCon in Atlanta in March of this year.
Last, but far from least, are the tandem quadrupole mass spectrometers from Thermo Fisher (formally Finnigan). The Xcalibur software is some of the most mature on the market and almost everyone that uses it thinks it is outstanding.
To make the best decision for you, you need to test drive all of them. Make sure you feel comfortable with software. That is the part of the instrument you will spend most of your time with. Get references from the manufacturers. Ask these references for the names of other people that they know that have these instruments. Always ask the questions, “What do you like least about your instrument?” and “What do you like the most about it?” Talk about down-time and how much maintenance is required.
Good luck -- have fun.
Maybe my reply will stimulate others to reply and we will get a good discussion going.
