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...

Safety, Productivity, Accuracy, Credibility, Education

Hi, Guys, I need your help on the my current concern NOW.

How do you value the "Efficiency" in the lab?

How do you evaluate "SPACE" (safety, productivity, accuracy, credibility, education) system of laboratory management.

Could you call me at NOW?

Thanks,

the Different between ESI and APCI sources

Update @ Friday

(MRL) Maximum Residue Levels for Pesticides in or on food and feed of plant and animal

On the regulation of (MRL) Maximum Residue Levels for Pesticides in or on food and feed of plant and animal:

I think European Union and Japan really did a good job on that.

It is really dilemma to the using of the Pesticides: Some "Environmental-concern" people always want to Pesticides free in all everything. Some"Profit-oriented" always try to use all high efficient Pesticides without caring the impact.

As for me, European Union and Japan: from the regulation view, they are good example for USA and China.

http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2008:058:0001:0398:EN:PDF