AN INTEGRATED ON-LINE METHOD FOR THE PRECONCENTRATION AND SIMULTANEOUS DETERMINATION OF METSULFURON METHYL AND CHLORSULFURON USING OXIDIZED CARBON NANOTUBES AND SECOND ORDER FLUORESCENT DATA

CAROLINA C. ACEBAL; MATÍAS INSAUSTI; PETR SOLICH; NATALIA E. LLAMAS; HANA SKLENAřOVA; MARCOS GRÜNHUT; LUCIE ZELENÁ; BEATRIZ S. FERNÁNDEZ BAND

MICROCHEMICAL JOURNAL

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2016 vol. 129 p. 90 - 97

0026-265X

Trace amounts of two sulfonylurea herbicides widely used for crops protection, metsulfuron methyl (MSM) andchlorsulfuron (CSF) were simultaneously determined taking into account the different kinetic photodegradationbehavior of their photoproducts in alkaline medium. As the analytes are present at trace concentration levels, apreconcentration by sorption on a mini-column packed with oxidized multiwall carbon nanotubes (ox-MWCNTs) at pH 3.0 was performed. The retained analytes were removed from the ox-MWCNTs mini-columnwith a mixture of ACN contained 10% (v/v) of NaOH pH 12.5. A total enrichment factor of 26-fold for a14.50 mLsample volumewas obtained. The eluate was photodegraded by UV radiation during 126 s and the fluorescentspectra corresponding to the analytes photoproductswere registered overtime between 300 and 500nm.The kinetic second order data were analyzed by unfolded-partial least squares-residual bilinearization (U-PLS/RBL) and multidimensional-partial least squares-residual bilinearization (N-PLS/RBL) algorithms. The relativeerror of prediction (REP %) for N-PLS/RBLwas 7.73% for MSMand 6.37% for CSF. In the case of U-PLS/RBL, this statisticalparameter was 7.75% for MSM and 7.23% for CSF, respectively. The limits of detection (LOD) were0.19 μg L−1 for MSM and 1.14 μg L−1 for CSF using N-PLS/RBL and 0.21 μg L−1 for MSM and 1.03 μg L−1 forCSF when U-PLS/RBL was applied.The entire procedurewas performed in an on-line integrated fully automated flowsystem coupled to a lowmercuryUV lamp(15 W, 254 nm) and a spectrofluorometer. In this manner, the preconcentration, photodegradationand detection steps were performed in a reproducible way.After optimization, the method was successfully applied to the analysis of real water samples obtained in thesouth part of Buenos Aires province and used for irrigation and consumption.