Might be this may be helpful

J Anal Toxicol. 2001 Nov-Dec;25(8):680-4.

Determination of glufosinate ammonium and its metabolite, 3-methylphosphinicopropionic acid, in human serum by gas chromatography-mass spectrometry following mixed-mode solid-phase extraction and t-BDMS derivatization.

Hori Y1, Fujisawa M, Shimada K, Hirose Y.

Author information

1Department of Analytical Chemistry, Niigata College of Pharmacy, Japan. [email protected]

Abstract

A method for the analysis of glufosinate ammonium (GLUF) and its metabolite 3-methylphosphinicopropionic acid (MPPA) in human serum by gas chromatography-mass spectrometry (GC-MS) was developed. Employing a mixed-mode cartridge with both anion exchange action and weak nonpolar interaction, we extracted GLUF and MPPA from the serum and carried out GC-MS analysis of their tert-butyldimethylsilyl derivatives. The detection limits of GLUF and MPPA were 10 pg and 1 pg, respectively. Full mass spectra of 100 pg GLUF and of 10 pg MPPA were easily obtainable. The recovery rate of 90.0+/-11.9% (or better) when the serum concentrations of GLUF and MPPA were 10-0.1 microg/mL. Results of 23 serum samples, from patients with GLUF poisoning, measured by this method correlate well with those derived from the conventional high-performance liquid chromatography method (r = 0.996). The developed GC-MS method is likely to become a useful analytical technique in clinical settings

why don't you try  to pass through polysuphone membrane/ Tlc nmembrane ie semipermeable membrane piece or pore size smaller than your molecular size rhe maximum 90 % water shall be discarded

Dear Mahesh, the target molecule is pretty small so that may not be such a good option.

there is a lot of recent works dealing with Glyphosate/ AMPA and glufosinate : a derivatizatiop step with FMOC agent followed by reconcentration on SPE cartridges. We use on line SPE combined with HPLC/MS/MS for detection and obtained very good detection limit for the three compounds. This method need the use of radiolabelled compounds for good quantitation but it's work very well !! We applied this method succesfully on groundwater , surface water and leachate