Glyphosate analysis in black tea.

[Indumini]

Can any one help me to analyze Glyphosate in black tea using LCMSMS? Tried several methods and the solvent linearity is very good but tea matrix match calibration or spiked samples not giving proper recovery. I need non derivatized method.

[Jesse Bischof]

It might be helpful to tell us a few of the methods that you've tried so far. At the very least, the type of column and solvents you're using.

[Indumini]

I have tried Acclaim Trinity column and also Accucore aq column with water ACN mobile phase.
Accucore column giving good linearity for solvent calibration.
Black tea 2 g weigh 10 ml water and 10 ml 1%formic in methanol extraction used and sonicate for 15 mins.

100ppb solvent calibration vial I add bank matrix 50 ul also then peak is suppressed and not giving properly. I think it is due to Glyphosate cheating effect. Can you suggest a method which can use for black tea?

[Jesse Bischof]

I have not performed a separation of black tea; however, on first look at the structure of glyphosate, chelation was my immediate thought. Priming the system and column might help. You could also think about going to a metal-free column like PEEK, glass, or Dursan coated.

[Indumini]

Can we use EDTA for get rid of this? Some metals may be present in tea matrix also.

[Andy Alpert]

It may not be necessary to use a metal-free column if you passivate the column that you do have. To accomplish this, pump a solution of 40 mM EDTA.2Na through the column for 16-24 hours at a low flow rate. Next day, flush out the EDTA with water and then condition and use your column as usual. This procedure passivates the entire HPLC flow path at the same time. If you want to passivate your injector valve too, then have the liquid flow through the valve during the passivation process.

If this works, then it will passivate your system and column for about 3 weeks. Repeat the process at that time.

Do NOT use EDTA.4Na. If you use any EDTA salt other than EDTA.2Na and then attempt to convert it to the disodium salt, then measure the pH before you start using it. More than one customer of ours has killed an expensive column fast because they didn't do this. You want a pH < 7.4.

[Jesse Bischof]

Can we use EDTA for get rid of this? Some metals may be present in tea matrix also.

Absolutely. As Andy pointed out. Make sure you follow the correct passivization process, and do it routinely, especially if you're looking to measure trace levels.


Phenomenex published this a few years back: https://phenomenex.blob.core.windows.ne ... 3fd589.pdf

They did the derivitized separation via RP in the first method, but in the second method they did an un-derivitized method utilizing HILIC mode on an amino column.

Best of luck!

[Indumini]

Thank you very much. I will try these methods. Tea matrix extraction and the clean up also need a guide.

[Kazimierz]

Cytryna (limon) is very harmfull with black tea together. I.m not using it simultaneusly. Aluminium from tea react with citric acid from the limon and forms harmful chelate. Additionally Randoap also forms >12 types chelates with aluminium of very toxic.
So It is firstly need to consider eliminate any aluminium from tea samples or blood plasma before glyfosate analysis with HPLC-MS/MS or be sure that Al-glifosate chelates will dissotiated with extraction process.

[JI2002]

If matrix effect causes the spiking recovery problem, an isotope labeled internal standard can be added to mitigate it.