LC/MS/MS Parameter Seeting

waters2695,Agilent Extend C18,waters2420ELSD?

(1) ELSD?
(2) & (3) : 225 nm.

For Traditional Chinese Herbs only: -> Chromatogram Peaks and Retention Time(Chromatographic Activity) -> Chromatographic finger identification...

Biosample Assay by LC-MS (2)

(1) Capillary Voltage: -3.0 kv.
(2) Cone Voltage: -40 v.
(3) Collision Energy: 18 ev.
(4) MRM: m/z 299.5 →m/z 255.2.

Biosample Assay by LC-MS (1)

Happy Spring Festivals 2009!

Ionization Suppression Summary

(1) Compounds That Cause Sensitivity Suppression.
-Salts can interfere with ionization and can cluster to complicate spectrum (but also aid in identification).
-Strong bases or quaternary amines can interfere with positive mode analytes, e.g. Triethylamine(TFA).
-Acid -Sulfuric/Sulfonicacids and TFA interfere in negative mode.
-Phosphate buffer and non-volatile ion pairing agents (e.g. SDS) can cause severe suppression and complex spectrum.

(2) Dimerization([2M+H]+) can occur at high concentration, leading to non-linearity during quantitation.
-DimerSignal at m/z = (MW*2) + 1.
-Can cause non-linearity at high concentrations.

Five Ways to Reduce Acetonitrile Consumption

The current global shortage of Acetonitrile has pushed us to find 5 ways to reduce thedependence on Acetonitrile

Option 1: Reduce column ID:

Reducing the HPLC column ID from 4.6 mm to 3.0 mm can result in > 50 % reduction in mobile phase consumption.

Option 2: Reduce particle size and column dimensions:

* Reduces solvent consumption
* Maintains resolution
* Reduces run time

Option 3: Reduce column length:

Option 4: Substitute Acetonitrile with Methanol:

http://www.phenomenex.com/images/methanal_replacement.gif

Option 5: Solvent recycling (Isocratic separations only)

Reference by Phenomenex.

VIP reference for the Method Transfer....

It's time to clean the Inlet....

Agilent 6890N ECD.
Temp Ramp: 80℃（1min)----20℃/min--- 260℃（15min)----5℃/min---300℃（3min),
Detector Temp: 300℃
Inlet: 250℃
GC Column:HP-5.

Baseline drift?

Maybe the collision energy (CE) is too LOW

(1) Maybe the collision energy is too LOW. The First MS is not full a fragment.
(2) Are you using ESI mode?
(3) If the Molecular weight is 237, for SIM -> Here are three characteristic ions (m/z) 164，149，122 I highly recommend them.
(4) MS-MS (MRM): Need to search online for the product ion and parent ions.
(5) If only need the full scan, why not adjust the concentration of analyte.

Hope it helps.

Agilent MassHunter could meet your request.

Go to MassHunter, File->TIC->.....

m/z (563.10761) is NOT the Molecular Ion? (II)

(1) Try to adjust the the capillary voltage: increase it a little bit each time.
If the the mass response of [M＋H2O －Ｈ]－ is decrease, the mass response of [M-H]- increase: then the m/z (563.10761) definitely is the molecular Ion.
If No such change happened, then the m/z (563.10761) definitely is NOT the Molecular Ion.

(2) From my view, the possibility of ［Ｍ＋Ｈ２Ｏ－Ｈ］( belongs to Molecular ion) is very low. Under ESI (-) negative mode, the trend of forming
the ［Ｍ＋ＨＣＯＯmore high.
Doubt the H2O have that much acidity for forming the ion peak.

m/z (563.10761) is NOT the Molecular Ion? (I)

What is the capillary voltage?
Did you try to increase a little bit?

Where M/Z 425 from? ( II )

Please click the elucidation Scheme for more details:
(Sorry for the confusion in the last post.)

From M/Z (471) to M/Z (425) , maybe belong the loss of Formic Acid (46) .

That is interesting Mass Spectrum, Good luck.

Where M/Z 425 from? ( I )

The molecular weight of your analyte is 548: 1st Mass is 549, 2nd Mass is 489, 3rd Mass are 471, 425.

Here is HUGE challenge for the structural elucidation of your analyte.
From M/Z (471) to M/Z (425) , maybe belong the loss of Acetoxyl M/Z.

But it is NOT right because there are two Acyloxy in your analyte.

Will Update you by Monday Night.

PPG Standard Prep for AB API4000

Come on, Man: Don't be silly to send us this Newbie question? Are you want to test our GC knowledge?
(1) Condition the GC Column according the manufacturer' recommend.
(2) Check the septum and the inlet, make sure NO cross-contamination -> inject the Blank.
(3) Optimize your method, change the Oven temp Ramp -> Higher the Initial temp, Low down the Temp Ramp.
(4) Low down the Split Ratio.
(5) Adjust the GC gas Flow Rate.

Sample Overload on Column? Example 2

That maybe Sample Overload: Low down the injection Concentration per injection or Injection volume per column. Or increase the Split Ratio that maybe help.

Sample Overload on Column?

From my view, maybe Sample Overload on the column.

Inlet Temp: 250， Initial Temp: 100; Hold 5 min，then 10 C/min to 230 C，Hold 5 min.
FID Temp: 280，Injection Vol. 0.2ul.

How do you define the Limit of Detection?

In figure 5b, [M+Na-H2O]+ ion peak at m/z 475 was observed. The peak is hidden by back ground. How do you define the limit of detection?

(1) From the reviewer's point, you should explain why the Low response in the Mass Spectrum?

(2) Optimize the Mass Spectrum of product ion: adjust the CID little by little, do not need to change the energy of cone voltage. low down the gas flow rate of CID, wait 10 min until equilibrium, increase the collision energy at Q2.

(3) If the Professor only care the Low response in the Mass Spectrum, here I have one "non-professional" shortcut: Inject twice in one time ( do not use the syringe pump), one could use low CID, other use high CID for about 2-5 min. Then use the second one as background to extract the First one. you definitely get high abundance on your mass spectrum. ( actually they are the same, but you could hide the response value in the Y axis, only put the abundance.)
Do not abuse the tip a lots, some reviewer hates that so much.

Good Luck...