COMPARISON OF ONLINE ENRICHMENT BASED ON ION-PAIR AND CATION-EXCHANGELIQUID-CHROMATOGRAPHY FOR THE TRACE-LEVEL DETERMINATION OF 3-AMINO-1,2,4-TRIAZOLE (AMINOTRIAZOLE) IN WATER
V. Pichon et Mc. Hennion, COMPARISON OF ONLINE ENRICHMENT BASED ON ION-PAIR AND CATION-EXCHANGELIQUID-CHROMATOGRAPHY FOR THE TRACE-LEVEL DETERMINATION OF 3-AMINO-1,2,4-TRIAZOLE (AMINOTRIAZOLE) IN WATER, Analytica chimica acta, 284(2), 1993, pp. 317-326
Aminotriazole is a polar and water-soluble organic pesticide and its p
reconcentration cannot be performed using either liquid-liquid extract
ion or solid-phase extraction with reversed-phase sorbents such as C-1
8 Silica, apolar copolymers or porous graphitic carbon. Aminotriazole
can be ionised and its ionisation constants have been measured in orde
r to select the best conditions for both the chromatographic analysis
using ion-pair chromatography and the extraction from water in its cat
ionic form. On-line preconcentration based on cation-exchange and ion-
pair chromatography have been investigated. Breakthrough volumes measu
red on small precolumns were higher than 50 mi with spiked deionised L
C-grade water and detection limits as low as 0.1 mu g l(-1) have been
obtained. In real samples, a competition with inorganic cations occurs
lowering the cation-exchange capacity. A chemical pretreatment consis
ting of oxalate precipitation and EDTA complexation was applied in ord
er to remove inorganic cations, but the sample volume that could be ha
ndled without breakthrough was lower and quantitative determination wa
s obtained at the 0.5 mu g l(-1) level. The same competition occurred
when carrying out preconcentration based on ion-pair chromatography wi
th a precolumn packed with an apolar copolymer that has been preloaded
with a sodium dodecylsulfate solution.