Coacervative microextraction: innovative preconcentration technique for determination of organophosphates pesticides in honey samples by GC-MS/MS

ARIEL R FONTANA; RODOLFO G WUILLOUD; ALEJANDRA B. CAMARGO; JORGELINA C. ALTAMIRANO

Santa Fe

Congreso; 2 nd Latin American Pesticide Residue Workshop; 2009

Universidad Nacional del Litoral. Facultad de ingeniería Química.

Introduction Organophosphates pesticides (OPs) are widely used for agricultural practices because they help to control pests and diseases. The extensive distribution of this group of pesticides caused several problems to apiculture industry including residues in hive products [1]. Honey is an exported product of Argentina and it is subjected to several quality controls. For the determination of pesticides in honey samples, routine methods typically involve several sample preparations steps such as extraction, clean-up and preconcentration before instrumental analysis. Objetives Development and validation of a method for OPs determination in honey of different regions of Argentine using coacervative-microextraction ultrasound-assisted back-extraction-gas chromatography–mass spectrometry (CM-UABE-GC–MS/MS). Material and methods 0.5 g honey samples contained into 10 mL aqueous solution pH 2 was extracted with xxxmL xxxmg/LTriton X-114 at 80 °C. Under these conditions the coacervate-phase started get agglomerated and decanted from the aqueous bulk. After centrifugation at 3500 rpm for 5 min the analytes were ultrasound-assisted back-extracted from the coacervate phase into hexane. Again, two phases were formed: the coacervate-phase (at the button of the tube) and the hexane one. A 1 µL of the hexane phase was injected and analyzed into the GC–MS/MS. Results Under optimum conditions, extraction efficiency (EE) ranged from 7 to 47 %. The LODs of the analytes were ranged from 14 ng L-1 to 213 ng L-1 with RSDs values ≤10.7%. The linear range was 500-100000 ng L-1 for Fenitrothion, Parathion and Methidathion; and 150-100000 for Chlorpirifos with r² ≥0.9992.The developed CM-UABE-GC–MS/MS method was applied to the analysis of pesticides in real honey samples; none of them reported the presence of the studied pesticides. Conclusion The CM-UABE can be successfully applied for extraction and preconcentration of polar pesticides. Even though, EE was low, the obtained LODs are suitable for real world applications. An important aspect of the proposed methodology to point out is the low organic solvent consumption. All these results disclosed that CM-UABE-GC– MS/MS is a sensitive, reproducible, rapid and versatile technique.