Determination of neonicotinoid insecticides in environmental samples by micellar electrokinetic chromatography using solid‐phase treatments

Abstract

A sensitive and reliable method based on MEKC has been developed and validated for trace determination of neonicotinoid insecticides (thiamethoxam, acetamiprid, and imidacloprid) and the metabolite 6-chloronicotinic acid in water and soil matrices. Optimum separation of the neonicotinoid insecticides was obtained on a 58 cm long capillary (75 μm id) using as the running electrolyte 40 mM SDS, 5 mM borate (pH 10.4), and 5% (v/v) methanol at a temperature of 25°C, a voltage of 25 kV and with hydrodynamic injection (10 s). The analysis time was less than 7 min. Prior to MEKC determination, the samples were purified and enriched by carrying out extraction-preconcentration steps. For aqueous samples, off-line SPE with a sorptive material such as Strata-X (polymeric hydrophobic sorbent) and octadecylsilane (C₁₈) was carried out to clean up and preconcentrate the insecticides. However, for soil samples, matrix solid-phase dispersion (MSPD) was applied with C₁₈ used as the dispersant. Good linearity, accuracy, and precision were obtained and the detection limits were in the range between 0.01 and 0.07 μg mL⁻¹ for river water and 0.17 and 0.37 μg g⁻¹ for soil samples. Recovery levels reached greater than 92% for all of the assayed neonicotinoids in river water samples with Strata-X. In soil matrices, the best recoveries (63-99%) were obtained with MSPD.

Simultaneous determination of thiamethoxam, clothianidin, and metazachlor residues in soil by ultrahigh performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry

“…As can be seen in Table 3, low LODs and LOQs were obtained for all the compounds. Finally, it must be said that both limits obtained with our proposed method for the pesticide analysis in soil are lower [7][8][9]11,[13][14][15][16][17]19,20] in most cases or slightly higher [3,6,8,18] than those previously published (Supporting Information Table S1). This demonstrates the excellent degree of sensitivity achieved with the proposed method.…”

“…Moreover, the results were most satisfactory not only regarding extraction efficiency (Supporting Information Table S1), but also in terms of simplicity (three stages: extraction, centrifugation and concentration), rapidness (< 30 min) and solvent consumption (16 mL). Consequently, our proposed sample treatment has shown itself to be a good alternative to the existing procedures for analyzing these pesticides in soil, as they required a longer period of time [6,8,12,13,[16][17][18], more steps/instrumentation [3,[6][7][8][9][10][13][14][15][16][18][19][20][21], and a larger volume/amount of reagents [3,[6][7][8]11,12,[14][15][16][17][18]20] (Supporting Information Table S1).…”

Pesticides from the EU First and Second Watch Lists in the Water Environment

“…Despite the fact that the Regulation provides two methods, which by definition should not entail excessive costs, they are still too expensive for many laboratories . According to Ettiene et al, LC‐MS and LC‐MS/MS are two of the most expensive techniques and may not always be available as a routine analytical method for pesticide residues in water . Furthermore, classical methods for sample preparation such as proposed by Regulation (SPE, LLE) are also often expensive, laborious and time‐consuming, and without sample pre‐treatment, the limit of detection established by the Regulation or lower cannot be achieved .…”

“…[20] According to Ettiene et al, LC-MS and LC-MS/MS are two of the most expensive techniques and may not always be available as a routine analytical method for pesticide residues in water. [123] Furthermore, classical methods for sample preparation such as proposed by Regulation (SPE, LLE) are also often expensive, laborious and time-consuming, [124,125] and without sample pretreatment, the limit of detection established by the Regulation or lower cannot be achieved. [120] The majority of routine water monitoring programs only include the most common pesticides (organochlorine, organophosphate etc.)…”

Determination of imidacloprid in water samples via photochemically induced fluorescence and second-order multivariate calibration

“…The low concentration levels of imidacloprid that may be present in these types of samples make sample treatments that involve extraction and concentration steps necessary. The extraction of imidacloprid from aqueous samples has primarily been performed using liquid-liquid extraction (LLE) [7] and solid phase extraction (SPE) on C18 [7][8][9][10]. On the other hand, due to its low volatility and relatively high hydrophilicity, the determination of imidacloprid in environmental water samples has primarily been performed using liquid chromatography methods with UV or diode array detection [11][12][13][14][15], mass spectrometry detection [16][17][18], ion chromatography [19] and micellar electrokinetic chromatography [8].…”