M. Takino et al., Determination of diquat and paraquat in water by liquid chromatography/electrospray-mass spectrometry using volatile ion-pairing reagents, ANAL SCI, 16(7), 2000, pp. 707-711
A method for the determination of the herbicides paraquat and diquat in wat
er was developed using liquid-chromatography/electrospray ionization-mass s
pectrometry (LC/ESI-MS). This method did not include any sample-concentrati
on steps. Only 0.1 M nonafluoropentanoic acid (NFPA) was added to the filte
red sample. An aliquot (200 mu L) of this sample was analyzed by reversed-p
hase liquid chromatography with the postcolumn addition of 2-propanol follo
wed by ESI-MS. Paraquat and diquat were detected using the [M2(+)-H+] ion a
t m/z 185 and 183, respectively. Quantification was performed by an externa
l standard method. The detection limits were 0.1 ng/mL (paraquat) and 0.2 n
g/mL (diquat). The repeatability and reproducibility were 2.1% and 7.4% for
paraquat and 2.7% and 8.1% for diquat.