Full text
| |
| Author(s): |
Grazielle de Campos Anaia
Total Authors: 1
|
| Document type: | Doctoral Thesis |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Conjunto das Químicas (IQ e FCF) (CQ/DBDCQ) |
| Defense date: | 2014-05-30 |
| Examining board members: |
Marina Franco Maggi Tavares;
Ana Valéria Colnaghi Simionato Cantu;
Jorge Cesar Masini;
Cassiana Seimi Nomura;
Maria Olimpia de Oliveira Rezende
|
| Advisor: | Marina Franco Maggi Tavares |
| Abstract | |
In this work a method for determination of different chemical groupes of pesticides (organophosphorus, carbamates, triazines, organochlorine and ureas) is proposed using HPLC-MS/MS in samples from occupational exposed agriculture workers. Isocratic and gradien elution in reversed-phase chromatography using a Synergi Max RP (150 x 4,6 mm, 4 µm) column were investigated for separation proposal. Isocratic elution conditions 45:55, 60:40, 70:30 ACN/water provided unsatisfactory results with retention factor from 0.5 to 20. In gradient elution, effects of gradient time (30 to 100 min), initial concentration of ACN (8 to 14%), flow rate (0.5 to 1 mL min-1) and temperature (30 to 40 °C) were studied for increasing resolution and decreasing analysis time. For different proportion of ACN in the mobile phase, the logarithm of retention factor has been ploted against solvent hydrogen-bond donor (α), solvent hydrogen-bond acceptor (β), dieletric constant (ε) and Hildebrand solubility (δH). Dimethoate and methomyl presented different behaviour in relation to others, explained by H intramolecular bond. Applying a two level experimental design having as response functions COF and CRS, combined factors such as flow rate, gradient time, ACN initial concentration and temperature were investigated. Optimal conditions were obtained in 0.5 mL min-1, 40 °C, 75 min e 5% CAN, for flow rate, temperature, gradient time and ACN initial concentration, respectively. Applying a LC-MS/MS system equipped with an ion trap mass analyzer, direct infusion of standard solutions of pesticides for knowledge of ion molecular peak and their MRM transitions was obtained. Quantitative experiments using UPLC-MS/MS were based in reversed-phase separation with a Acquity UPLC HSS T3 (50 x 2,1 mm, 1,8 µm) column, mass spectrometry instrument equipped with triple quadrupole mass analyzer at positive ion polarity. Quantifying and confirming ion transitions were monitored for each pesticide compound. Linearity in range of 0.25 to 50 µg L-1 was established for all pesticides with high coefficients determination R2 0.999 were obtained. The method LOD varied between 0.192 to 3.19 µg L-1. LOQ varied from 0.582 to 13.6 µg L-1, with coefficient variation below 20% CV. Recoveries for samples spiked at 0.75 µg L-1 concentration level varied from 55.7 to 72.6% and precision in terms of CV between 1.94 and 19.1% CV. Spiked samples at 10 µg L-1 concentration level varied from 99.1 to 105% and precision between 0.751 and 8.98% CV. Recoveries for samples spiked at 50 µg L-1 concentration level varied from 99.5 to 101% and precision from 0.877 to 5.94% CV. From 25 samples quantified, 13 presented concentration values in linear range of the calibration curve. These values varied from 10 to 50 µg L-1. (AU) | |
| FAPESP's process: | 09/10296-9 - Pesticides multiresidue determination by HPLC in context of occupational exposure |
| Grantee: | Grazielle de Campos Anaia |
| Support Opportunities: | Scholarships in Brazil - Doctorate |