Analysis of trace levels of pesticides in rainwater by SPME and GC-tandem mass spectrometry after derivatisation with PFFBr

Abstract

Solid-phase microextraction (SPME) was used for the analysis of some pesticides (bromoxynil, chlorotoluron, diuron, isoproturon, 2,4-MCPA, MCPP and 2,4-D) in rainwater after derivatisation with PFBBr and gas chromatography-ion trap mass spectrometry. The derivatisation procedure was optimized by testing different methods: direct derivatisation in the aqueous phase followed by SPME extraction, on-fibre derivatisation and derivatisation in the injector. The best result was obtained by headspace coating the PDMS/DVB fibre with PFBBr for 10 min followed by direct SPME extraction for 60 min at 68 degrees C (pH 2 and 75% NaCl). Good detection limits were obtained for all the compounds: these ranged between 10 and 1,000 ng L-1 with a relatively high uncertainty due to the combination of derivatisation and SPME extraction steps. The optimized procedure was applied to the analysis of pesticides in rainwater and results obtained shows that this method is a fast and simple technique to assess the spatial and temporal variations of concentrations of pesticides in rainwater.

Utilization of long duration high-volume sampling coupled to SPME-GC-MS/MS for the assessment of airborne pesticides variability in an urban area (Strasbourg, France) during agricultural application

“…Variabilities are in many case relatively important and are the consequence of the successive steps (ASE C evaporation C SPME C GC-MS/MS) used in the method. However, these variabilities are in the same order of magnitude with those obtained by Scheyer et al, [16] Salqu ebre et al, [18] and Raeppel et al [15] for the same type of pesticides.…”

“…[13] It was observed in previous studies that the optimum temperature and time of extraction varied strongly in function of pesticides. [13,[16][17][18] Indeed Salqu ebre et al [18] have observed that polar pesticides present maximum extraction efficiency when exposed at low temperature while apolar pesticides present maximum extraction efficiency when exposed at high temperature. Then, three temperature of extraction (40, 60, and 80 C), permitting the higher response, were determined and selected for pesticides under study ( Table 1).…”

“…This was also observed by Jaber et al (2007) for bromoxynil and confirmed by Raeppel et al [15] for aryloxyacids herbicides (mecoprop-p, triclopyr, 2,4 MPCA and 2,4D). The SPME solution was acidified to pH 3 in order to obtain protonated aryloxyacids [16] and this pH modification did not alter the other molecules that were extracted by PDMS/DVB fiber. [13] It was observed in previous studies that the optimum temperature and time of extraction varied strongly in function of pesticides.…”

Innovative Monitoring of Atmospheric Gaseous Hydrogen Fluoride

“…Kage et al, 2008 [36], used PFBBr followed by liquid-liquid extraction with n-hexane; in a similar manner, we have developed a new and different approach by using on-sample derivatisation followed by HS-SPME. A study proposed three procedures for SPME derivatisation by using PFBBr: on-sample and HS or direct immersion extraction, on-fiber, and in the injector [37]. A sensitive GC method has been established for determining anions, including cyanide, formate, acetate, iodide, nitrite, nitrate, sulphide, and thiocyanate, as their volatile organic derivatives by using PFBBr [38–42].…”

FI-photoinduced Chemiluminescence Method for Diuron Determination in Water Samples

“…As diuron is thermally unstable, it has to be changed into a stable derivative in order to use gas chromatography (GC). For instance, ethyl iodide has been used as an alkylating agent, 18 as has iodoethane with sodium hydride 19 or pentafluorobenzylbromide, 20 while heptafluorobutyric anhydride has been used for acetylation of various phenylureas. 21 It complicates the analysis, which is why liquid chromatography (LC) with spectrophotometric 22,23 or fluorometric detection is usually preferred.…”