Thermo TSQ from a Sciex-users vantagepoint

[ublokr]

Hello, I use Sciex API 3000 and API 4000 triple quads but need to learn a
Thermo "TSQ" (the only name given in the manual or on the machine). Looking on a Thermo model release timeline, I see no such beast, but am told it was after the 7000, before the Quantum.
Can someone please answer these questions?
- Sciex machines have no heated capillary. Just how sensitive are TSQ
heated capillaries to salt? How easily unclogged when clogged?
- What are key maintenance/cleaning steps?
- What are some of the major "don'ts" with this machine?
- What things CAN'T the Windows version of Xcalibur do for which I need to
resort to the 'black screen' utility?
Thanks.
Joe

[MaryCarson]

Are you talking about the floor model TSQ that can be rigged with either a GC or LC interface? Is the spray in-line with the capillary, or orthogonal? If at all possible, I'd avoid salt on your TSQ, especially if you have the "in-line" version. The heated capillary is easy enough to clean (daily spritzing with methanol/water while reaming with a very narrow gauge tubing sold by Thermo for that purpose), but I don't think it will last very long between cleanings if you run NaCl or phosphate buffers. Ammonium acetate, formate, and various volatile acids are fine at moderate concentrations.

I ballasted pumps more frequently on TSQs than I do on Sciex.

I don't recall ever having to use "black screen" utilities in Xcalibur.

[ublokr]

Mary,
Thanks. That is an exact description of the model, and the spray indeed is inline. Since asking my questions, I received a reply from the vendor of this machine (I sent him a timeline display of Thermo models, from a Thermo website showing nothing between a 7000 and a Quantum), and he admitted it was a TSQ 7000. That helps, as I've long read of the strengths and weaknesses of that model. Your reply certainly helps, too. I see three burnt capillaries in drawers here (plus lots of bent and broken hypo tubing and a bent guitar string!) so this does appear to be a weak link, and your point about salts, etc., causing bigger problems with inline spray into Q0/Q1 is even more sobering. I'll be really careful. When I described to the vendor "3 cm of emulsion over the oil level", he said perhaps I should change the oil. I guess so!
One oddity for a Sciex user is that single or multiple reaction monitoring methods (SRM, MRM) seem to be specified from the same Xcalibur screen as scans -- I guess by entering a suitably narrow "scan" range for the product ion. Or am I missing a screen for non-scan methods? How can I specify resolution on the precursor? Is the default 0.25 mz units?
Do users usually tune their own, or wait for the field tech? I'm looking for a method.
Lots of questions...thanks for your help!

[yangz00g]

I am a user of a newer vesrion TSQ Quantum QQQ. Speaking of the Xcaliber, it's not a very user frriendly software, IMO.

Yes, Xcaliber uses "scans" for both SIM and MRM. Thermo Rep claims that a narrower scan window gives better S/N. For the Quabtum, you can put the number as low as 0.001amu (any comments on this?). Remember, this is scan window, not resolution.

Hope this help

[MaryCarson]

We tuned our own. Did most of our own maintenance, too. I have "fond memories" of cleaning pump oil off of Q0 after an unexpected power outage. Everything is on an UPS now.

I thought Xcalibur was easy and intuitive, and pulled my hair for the first few months on Analyst, but then I went in the opposite direction from you. I see advantages/disavantages to both now.

Once upon a time, we had a TSQ 7000 method set up with the following ESI conditions. Hope this gives you someplace to start. Item 5.6.2.5 is especially important to follow if you run an ACN mobile phase. This method was set up to optimize sensitivity at the expensive of selectivity. Hence monitoring products at a width of 1.5. I think the default unit resolution width value was 0.7.

5.6.2. Electrospray setup. The following settings were typical of those in use during method validation. These conditions provided reasonably stable performance and good sensitivity.
5.6.2.1. Sheath gas 50 psi
5.6.2.2. Auxiliary gas 40 (arbitrary units)
5.6.2.3. Heated capillary 350°C
5.6.2.4. Needle voltage 4.5 kV
5.6.2.5. Strip the exit of the fused silica transfer line of its polyimide coating by exposing it very briefly to a flame. (Remove the char with a wet wipe.) Otherwise the coating will creep past the tip when exposed to acetonitrile in an electric field. Adjust the tip of the fused silica to be flush with or barely inside the steel electrospray needle.
5.6.3. Electrospray through Q1 optimization. Adjust LC mobile phase to provide ACN + water (25 +75) at 200 uL/min. Use a syringe pump to infuse CAP into the mobile phase post-column (use a 10 ug/mL solution at 2 uL/min). Monitor the [M-H]- ion at m/z 321 in negative ion Q1 mode. Use the instrument’s manual tune capability to optimize the capillary, tube lens and lens 1 voltages. Reduce Q1 resolution (adjust PRES to provide peak widths about 2 amu) to increase response by about three-fold.
5.6.4. MS/MS optimization. Set Q1 to select the CAP [M-H]- ion at m/z 321. Monitor the major CAP ions at m/z 152, 176, 194, and 257. Adjust the CID voltage and CID gas pressure to maximize the m/z 152 signal. Typical values used during method validation were 20 V (COFF) and 2.8 mTorr argon. Reduce the Q3 resolution to provide peak widths of about 1.2 amu at half height (Adjust DRES). This may cause a slight downward shift in the centroided mass assignments. Typical relative abundances for the CAP MS/MS spectrum under these conditions were: 152 (100%), 257 (50%), 194 (35%), 176 (30%), 321 (25%). Acquire full MS/MS spectra of CAP and m-CAP to check the mass assignments.
5.6.5. Data acquisition. Use selected reaction monitoring (SRM). Select m/z 321 in Q1. Use Q3 to monitor a 1.5 amu width centered on the m/z values determined in the MS/MS spectra. Nominal masses are 152, 176, 194, 207, 257. Dwell time is 0.2 sec per ion.
5.6.6. Routine maintenance. The instrument should be maintained and calibrated according to applicable procedures. Before and after each batch of standards and extracts, flush the heated capillary with 50:50 methanol:water for 3 seconds (repeat 3x). Monitor the API skimmer pressure during the batch. If the capillary starts to become clogged, API skimmer pressure will be reduced and sensitivity will go down. Typical pressures during method validation were 980 mTorr (LC flow diverted) and 1010 mTorr (LC flow to MS). If pressure is dramatically reduced, use the 0.26 gauge hypodermic wire provided by ThermoFinnigan to ream out the capillary.
5.6.7. Instrument start-up. Allow the system to equilibrate at least 30 min after removing the heated capillary cap and turning on gas flow and liquid flows. Make at least one injection of a blank before beginning analysis.