GC-TOF & INSIGHT Flow Modulator

 Normally motor rotation is 1000 Hz. During venting process, once motor rotation goes below 500 Hz, nitrogen will purge the flight tube.

·       Minimize moisture during venting cycle

·       Able to pump down rapidly again

Make sure high voltage is off

At 5 min: flight tube maintenance when newly installed. Size 5 allen key

At 9.20 min internal of flight tube

Note flight tube screw have washer. Blanking plate don’t have washer

At 11.20 min removal of blanking plate (very important to know where is it stored)

At 13.30 transfer line installation start.

For tuning

Low ionization use DHN

PFTFBA for tuning 70 eV

16.36 min: installation of maku tip (ceramic) installation on transfer line

17.20 min: hole of the ion source where the macor tip+transfer line will go into. Column will pass through the centre into the ion source

18.00 min installation of the macor tip

·       Hold down the string on the transfer line

·       Thinner part of the macor tip will goes into the source

·       Thicker part put on the transfer line while holding down the spring turn it counterclockwise till it bites on the spring

 19.20 min: orientation of how to install the transfer line

 ·       Caliber (calibration) gas on left

·       Plug connector for heating cable on right

·       Impt install wrong way maku tip will snap

When tightening: Screw at 12 and 6 first to secure

20.40 min:  move flight tube lid out to see how the maku tip+transfer line properly goes into the hole of the ion source

DO NOT LET GO TILL SECURE

Screw at 12 and 6 first to secure

Finger tighten enough then secure with tools (lightly tightened)

Secure evenly the rest

Make sure to the left we have about 20 cm for maintenance.

28.15 min installation of the caliber gas and heating cable

Need 2x 5/16 inch spanner. Secure bottom, loosen the top blanking nut.

30.36 min Loop the connecting line to reduce excess length

Hand tightened. Then tightend the nut same way with the 2 spanner. Secure bottom make sure it don’t move. Tightened till feel resistance, and add another 15 more degree. As tight as possible.

33.50 min: installing heating cable to the right

37.00 min: nipple of ferrule facing away MS, point to the nuts. Flat part to MS

38.00 min: securing flight tube

39.36min left 2 to 3 thread left. Do not bolt down! Thread should be loose

40.50 min: put on the bracket before securing the nut and ferrule

Note: here Anthony is blinding the detector.

Starting the vacuum, pumping down the system.

 

0.19 min: purpose of the bracket.

1.09 min: starting of the pumping down process.

2.13 and 4.03 min: Turn the Roughing pump on first. Wait for flight tube pressure to reach 3.00 E+00

Then can turn pump on (This is tmp turbo pump switch) (After flight tube reaches 3.00 E+00 then can turn it on).

4.34 min able to auto vent. Cool down source and transferline first below 125 degree C. then turbo pump off

Start of video, turn off the roughing pump. After prolong duration flight tube pressure does not attain 3E+00 using external roughing pump

0.21 min: symptoms of imperfectly sealed flight tube. Screw cannot move easily.

1.40 min: how to pump nitrogen into the flight tube. click open vent valve. Nitrogen will be pump into the flight tube.

 This can be done to rapidly get rid of residual vacuum. Make it easier to re-seat the lid.

2.15 min: how long can the system last once shipped with nitrogen already purged in system, without turning the system on.

·       Turn roughing pump on manually with external power supply.

·       Protect the MCP detector (multi channel plate)

·       MCP sensitive to moisture will crack!!

4.42 min: if concern about cracking MCP plate, pump down for a day or 2 before applying voltages (don’t turn on high voltage).

4.55 min: what happen in the flight tube. ionization till detection

5.31 min: if roughing pump does not drop flight tube pressure 9/10 times is due to flight tube lid.

5.47 min: if transfer line – blind ferrule- nut interface slightly loose, will not cause this. At most minor leak.

5.57 min: flight tube lid totally flush if properly seated. Screws nuts are easily moved, no resistance. Do not bolt down.

7.30 min: if takes roughing pump like 30 mins to reach 3 E 00. There is a leak. Stop!

8.46 min: turning turbo pump on.

 

9.25 min: motor rotation if cannot hit 1000 Hz in 10 mins, it will turn the turbo pump off as there is a serious leak to protect itself.

9.45 min: successfully pump down when motor rotation hit 1000 Hz. Initially about 30 W for motor power, till pump down then do not need to work as hard. Motor power will drop.

10.21: definition of cut off value.

System is in ideal state when flight tube vacuum dropped below 3.5 E-006. Then it will allow us to turn the voltage on and start heating.

11.30 min: after 1 hour can perform qualitative analysis once pump down. Quantitative let vacuum mature overnight. For IDL testing leave it overnight, better background.

12.30 min: pressure limit high = alarm limit. Pressure limit low = ideal working condition.

13.40 min: if a lot moisture, will struggle a bit to lower further at x E-005

2min: Thermo vs flow: Thermo very big, flow smaller

5.30min: why need a modulator. Example of fitting 2 columns of very different stationary phase with just press fit joint.

will have very bad resolution.

7.00min: GC+GC (Shimadzu MDGE heartcutting) vs GCxGC (GC by GC)

12.20: GCxGC: Primary column flow rate 0.5 ml/min. very slow flow rate will have wide peak. But allow us to slice it up.

 

13.15min: 2nd Dimension column high flow rate 20 ml/min.

X axis took place in min (1st dimension)

Y axis in sec (2nd dimension) (separation took place isothermal)

14.00 min:          1D column dimension: 20m x 0.18 mm (or 0.15 mm)  x 0.18 um (or 0.15 um) 

                             2D dimension: 2m to 5m x (0.25 mm) x 0.1 um

19.16 min: raw data reconstruction to GCxGC data

25.00 min: gc x gc focusing effect higher apex value

0.30 min: how the modulator works

1.00 min: fill mode

1.15 min: flush mode

2.30 min: zero mechanic switch on the plate. Explanation how the control valve works. Control via pressure differential to direct where the sample from 1st D column to sample loop, or from sample loop to 2nd D column

7.02 min: Bleed line function; 0.1 mm ID x 5m very small very high impedance

8.10 min: common issue faced with flow insight modulator. Column break and choked. Affects the flow dynamics. One

9.20 min: when choked, will face constant leaking issue. Cannot seal properly

9.30 min: how to clean up when choked. Fastest way pressurise use air duster

12.50 min: in Psi pressure diff of 25 psi will be able to maintain the diff in flow. 80 is consider high. Inlet to ambient is around 25 to 30 psi. When ramp to top temp, the diff can be around 50 to 60 psi.

15.20 min: pressure ramp to ensure constant flow when temp raises (similar to constant linear velocity control of shimadzu AFC). Below depict the pressure ramp calculator

 17.23 min. advantage of thermos over flow modulator. Flow method requires high flow rate in 2nd dimension and only max 4ml per min can goes into the MS (no MS can take 20 ml/min flow rate). Diluted the sample.

Purge splitter control via a flow controller is there to ensure a constant flow of 4ml per min goes into the MS from start to end of run (regardless of temp ramping).

19.00 min why a good idea to complement FID with MS as detector for gcxgc. Hard to saturate FID, good for quantitation. Quantitation via FID, qualitative via MS.

21.50 min reverse fill flush vs forward fill flush (older technology by agilent, no one really use this anymore)

22.50 min why not do not set method to fill sample loop to 100 percent. Will lose signal via bleed line. Forward fill flush if that happens, the excess will go directly to the detector.

2D tailing will be observed. Such effect is less pronounce in reverse fill flush.

 25.55: advantage of flow over thermos, flow suitable for very volatile compounds. Such volatile compound cannot freeze it. Eg less than c6

 28.15: group type analysis

 Eg jet fuel. Very easily get the area percent of each group

29.40: FID complement MS for quantitation example

30.27: eg GCxGC TOFMS complementing other kind of detector like ECD/SCD

31.00: Tandem ionisation 14 eV and 70eV

32.13min: How the valve looks like

32.17: gcxgc and heart cutting

Heart cutting purposely overfill the sample loop goes to the bleedline connect to another detector

33.00 calculator excel

- x and y pri and secondary column flow, help u calculate how much split to your tof and to your fid

- what length of time can u set for sample loop to be fill/optimum setting

6.10: Chemometrics defination: combinations of chromatography and statistic

8.05: Max scan speed of TOF is 400 Hz. (Shimadzu Quadropole ~100Hz (to check)).

We just need to run at around 50 Hz.

GCxGC peak width around 100 to 200 ms.

Agilent scan around 23 Hz only.  

11.15: Mass accuracy around 50ppm (around 3 decimal places)

12.36: TOF vs Quadrupole

14.30: Schematic diagram of TOF

Note potential differences of 5000 v. U bent.

16.10: how TOF works. Record time it takes for ion to leave the ion source to detector. Raw data in nanosec.

17.00 min: logic behind Sepsolve TOF. Larger molecules requires more kinetic energy to leave the source

17.30 min: MCP Detector honeycomb, ions inside it will bounce faster and faster and then hit the detector with higher kinetic energy = stronger signal

The system has 2 MCP plate for amplifying the signal

18.55 min: during PM extending the lifetime of the MCP plate. Can rotate to avoid the ion burn.

19.15 min: all ions are focus as ion package then send out at the same time (except those m/z range we did not want to see). The frequency of firing is basically the scanning frequency in Hz. In GCxGC this is around 50 Hz in 1D GC around 4 Hz.

20.38: NIST library built using Single Quad.

Larger m/z need more kinetic energy = slower in TOF flight tube. Response will be slower because of the way MCP plate detect signal. Mass discrimination effect. Eg Sepsolve competitor

The high potential difference 5000 v larger ions will be pulled towards the detector to offset mass discrimination effect.

23.00 longer flight tube better mass accuracy but more pronoun mass discrimination. Diff approach from Sepsolve aiming to get better match in NIST

Good for unknown unknown analysis.

25.00 using TOF high res mass spec to guess molecular formulae. 3 decimal places. Useful for unknown analysis. Isotope pattern.

26.25 min extended dynamic ranges introduction. Define a particular ion how much kinetic energy it has when it leaves the ion source. Enables a wide dynamic ranges low sens and high sens and plot together in the software. Useful in situation you not sure of the concentration. Minimise the risk of saturating the detector.

29.32 Compound explorer intro.

32.50 tandem ionisation example. 70ev vs 12 ev fragmentation peak. Still can use 70ev to search in NIST

Can build own low EI library ourselves.

35.19: can use Tandem ionisation to differentiate between isomers.

36.09 match factor definition

37.30 example of how to use their software using TI data

39.52 the software is capable of making use of rentetion index information (AART)

42.30 need to convert shimadzu data to CDF format.

0.00 Venting the MS

Instrument will cool the transfer line and ion source to 125 degree, DO NOT TURN OFF THE HIGH VOLTAGE AT THIS STAGE.

Then it will vent down.

 

1.00 min High voltage should be turn off when doing maintenance inside the TOF

2.05 min cool rate transfer line will be faster than source

2.55 min things to observe flight tube pressure and motor power and motor rotation.

When transferline and source cooled to 125, turbo will turned off, motor power and motor rotation will dropped eventually reached zero.

3.36 min. note: 4 E-07 in situation when the benchTOF2 is blinded with no column flow.

Flight tube pressure

Zero flow < 1 D GC (~1.5ml per min) < GCxGC (4ml per min)

1.00 min: left click Workflow Sequencer

Sequence: For acquisition controlling the TOF

Processing: post processing. Eg integration, deconvolution

History: past runs

2.00 min. Left click on Sequence tab

2.10 min creating new sequence

Choose <new project> can create and named new project

Left click this can choose the path where is it being saved.

Then name the sequence file. Can have multiple sequences in the same project

 3.50 to delete the sequence right click can delete

 4.13 min: performing AO (auto-optimisation: we call it tuning in shimadzu)

Left click on the newly created project AO

 For file name avoid using scripting symbols like µ # // this sort, will cause bug

Comment is fine as it is

{d} this is the date

{n} number auto increment, if same file name first run will be 1, and so on and so fro

If same file name, computer actually will auto put a time stamp behind

6.29 min. Double left click Global Method

 Choose template method. Template method here are hard coded. Cannot be over written.

 Choose auto-optimise BenchTOF. It will load onto the Global Method.

 Right click view method

 Pre-run pause: should not need to touch. don’t touch. Slight delay before TOF starts collecting data.

Filament voltage also don’t touch just leave it as 1.6 V. For brand new system, should not need to change this above 1.6V

Define transfer line and ion source temperature, make sure they are the same as the acquisition method.

Mode selection drop down option

 We will do standard AO (at 70eV) for this exercise. Can use this to just do 14ev if we just want to tune soft ionization.

 We can click on the pad lock and unlock it. Save it as a new name

 Choose Yes

 Rename the file

 Now we can edit the parameters in the sequence

 This is useful for method development can run sequence of multiple setting. Rather than save eg 10 different method just because of slight difference in parameters.

If select TI, we will have one more mode of auto-optimisation

 Lower ionization, drop in sensitivity. If struggle to see try -16, but if have slightly higher in abundance can try -12.

The library trainer passed us is at -14.

14min: if a warning popup when we save the method due to change in parameters of the source. This is normal. No need be alarm. Will not see such warning if the method save the parameters is same as current setting.

 

14.45: the tune files are saved in the background configuration. If you run a acquisition method that it does not have the tune file for it, the software will choose the tune file closest to it.

Eg you did not tune at -14 eV but you perform acquisition at -14 eV. You have a tune file at -16 eV. It will use that

A warning popup will appear.

16.00: tune file will keep overwrite the last one for the similar eV

To view old tune file info

 Right click on BenchTOF, choose generate report.

 Can generate report according to mode: Standard AO or Tandem AO,

Ionization energy:

Or filament current

 

18.00 min starting the auto-optimization tuning
Starting Click play.

 It will perform short validation to make sure file path is ok. If make an external drive and unplugged will cause issue.

Instrument will hang and stopped if drive not found.

After clicking play a popup will appear. Ignore them all when doing a tune.

 The repeat features is useful to keep repeating that line. Flush contamination until its cleared.

  

23.02 min during auto tuning.

First thing it does is make sure getting ionisation

Then check for electronic noise on detector by scanning the whole mass range. This process is known as DarkCounts

 If very high Darkcount means something wrong with detector maybe got dust on MCP.

 The !!! marks are signs the detectors are overloaded (very normal during AO, ignore)

 It also check for SigmaNoise. That is the electronic noise

  

26.55 min Acceptance criteria

 low eV (14 or 16)
 70 eV
 For 70 eV mass resolution above 1100 = passed else fail

For 14 or 16 eV mass resolution above 800 = passed else fail

Ion intensity (70 eV) 2000000 passed (2 million)

Ion intensity (low eV) 500 000 (0.5 million)

 

29.40 min: generating of report note the value here have to divide by 40 as its using older scripting for older instruments of Sepsolve

Right click on

Choose Generate Report. On the new popup choose the setting required

Values here divide by 40 will be same as what we got in the sequence view.