Chromatography Forum

Hi all.

So our LCQ Deca has stopped giving us a signal mysteriously when injecting something. We are trying to manually inject MeOH into the system to get a signal, and a lot of random high weight molecular ions seem to be appearing but nothing else after injection. There is proper instrument communication and gas flow, all the lights (power, vacuum, communication, and system) are green and the scan light is blinking blue. Everything seems to be OK on the surface.

Any suggestion?

I am also getting an error that the "Syringe Pump Out of Sample!" even though it's turned off...

Me and my colleague are not LC/MS experts and are trying random things, but any direction would be appreciated. I think calling for help is out of the question right now.

Apologies, we are trying to inject acetophenone in MeOH

OK. We have worked for a couple hours and ran the diagnostics, the detector seems to have failed? Our dynode voltage is -14.93 kV and the multiplier voltage is -6.3 kV. Is this normal. Is there any troubleshooting we can do for the detector to get it working?

Here were the results for the diagnostics:

Begin All Diagnostics Status Test Loop
10:58:41: Multiplier (V) -- Out of range: -6.299
10:58:41: -205 V supply voltage (V) -- Out of range: -189.568
10:58:42: Multiplier (V) -- Out of range: -4.736
10:58:42: -205 V supply voltage (V) -- Out of range: -189.691
10:58:42: Multiplier (V) -- Out of range: -4.736
10:58:42: -205 V supply voltage (V) -- Out of range: -189.568
10:58:42: Multiplier (V) -- Out of range: -6.299
10:58:42: -205 V supply voltage (V) -- Out of range: -189.445
10:58:43: Multiplier (V) -- Out of range: -4.736
10:58:43: -205 V supply voltage (V) -- Out of range: -189.568
10:58:43: Multiplier (V) -- Out of range: -4.736
10:58:43: -205 V supply voltage (V) -- Out of range: -189.568
10:58:44: Multiplier (V) -- Out of range: -4.736
10:58:44: -205 V supply voltage (V) -- Out of range: -189.568
End All Diagnostics Status Test Loop
10:58:44: Multiplier (V) -- Fail
10:58:44: -205 V supply voltage (V) -- Fail

All Diagnostics Status Test Results

+15 V - Pass
+150 V - Pass
+205 V - Pass
+24 V - Pass
+28 V - Pass
+35 V - Pass
+36 V - Pass
+5 V - Pass
-15 V - Pass
-150 V - Pass
-205 V - Fail
-28 V - Pass
8 kV PS voltage - Pass
Ambient temp. - Pass
Analyzer temp. - Pass
Aux gas flow - Pass
Capillary temp. - Pass
Capillary voltage - Pass
Convectron - Pass
Detected RF - Pass
Dynode voltage - Pass
Entrance lens - Pass
Intermultipole lens - Pass
Ion gauge - Pass
Main RF DAC - Pass
Multiplier setting - Pass
Multiplier voltage - Fail
Multipole 1 offset - Pass
Multipole 2 offset - Pass
Multipole RF mod. - Pass
Multipole det. RF - Pass
RF amp. output - Pass
RF det. temp. - Pass
RF gen. temp. - Pass
RF modulation - Pass
Sheath gas flow - Pass
Trap DC Offset - Pass
Tube/gate lens - Pass


Starting All Diagnostics Scan Tests

10:58:44: Start scan readback test on device Auxiliary amplitude (V)
-- 0 to 83.2
10:58:47: Scan readback test ended
10:58:48: Result: PASSED
10:58:48: Start scan readback test on device Main RF DAC (16-bit) -- 0 to 65535
10:58:52: Scan readback test ended
10:58:52: Result: PASSED
10:58:52: Start scan readback test on device Vernier det. RF amp. (V)
-- 0 to 65535
10:58:56: Scan readback test ended
10:58:56: Result: PASSED
10:58:56: Start scan readback test on device Vernier RF DAC (16-bit)
-- 0 to 65535
10:59:00: Scan readback test ended
10:59:01: Result: PASSED
10:59:01: Start scan readback test on device Multipole RF DAC (V) -- 0 to 1000
10:59:04: Scan readback test ended
10:59:05: Result: PASSED
10:59:05: Start scan readback test on device Multipole 1 offset (V)
-- -132 to 132
10:59:09: Scan readback test ended
10:59:09: Result: PASSED
10:59:09: Start scan readback test on device Multipole 2 offset (V)
-- -132 to 132
10:59:13: Scan readback test ended
10:59:13: Result: PASSED
10:59:13: Start scan readback test on device Multipole lens (V) -- -132 to 132
10:59:17: Scan readback test ended
10:59:17: Result: PASSED
10:59:17: Start scan readback test on device Multipole det. RF amp.
(Vp-p) -- 0 to 1000
10:59:21: Scan readback test ended
10:59:22: Result: PASSED
10:59:22: Start scan readback test on device Trap Offset (V) --
-133.786 to 133.882
10:59:25: Scan readback test ended
10:59:26: Result: PASSED
10:59:26: Start scan readback test on device Tube gate (V) -- -200 to 198.01
10:59:30: Scan readback test ended
10:59:30: Result: FAILED
10:59:30: Start scan readback test on device Multiplier (V) -- 0 to -2200
10:59:43: Scan readback test ended
10:59:43: Result: FAILED
10:59:43: Start scan readback test on device Aux/sweep gas flow (arb)
-- 0 to 60
11:01:17: Scan readback test ended
11:01:18: Result: PASSED
11:01:18: Start scan readback test on device Sheath gas flow (arb) -- 20 to 100
11:02:53: Scan readback test ended
11:02:54: Result: PASSED
11:02:54: Start scan readback test on device Capillary Voltage (V) --
-132 to 132
11:02:57: Scan readback test ended
11:02:58: Result: PASSED
11:02:58: Final result: FAILED


Thanks!!!!!

The EM voltage shouldn't ever get anywhere near -6.3kV. I didn't even know a voltage that huge was possible. It will increase with age of EM horn but should sit around 2kV I'd imagine. I think it only changes when you do a tune. This instrument is no longer supported properly by Thermo, but there's an off-chance they might be prepared to advise, particularly if they think you might consider buying a new instrument in a few years time if only they can convince you how helpful they are...

Thanks. Begged Thermo tech support and got someone helpful. He thinks its either the convection gauge or the electronics. I am going to run a few diagnostics (pressure test, and an electronics diagnostics screen graph) to see if that gives any idea.