A new cloud point methodology was successfully used for the extraction of carcinogenic pesticides in milk samples as a prior step to their determination by spectrophotometry. In this work, non-ionic silicone surfactant, also known as 3-(3-hydroxypropyl-heptatrimethylxyloxane), was chosen as a green extraction solvent because of its structure and properties. The effect of different parameters, such as the type of surfactant, concentration and volume of surfactant, pH, salt, temperature, incubation time and water content on the cloud point extraction of carcinogenic pesticides such as atrazine and propazine, was studied in detail and a set of optimum conditions was established. A good correlation coefficient (R2 ) in the range of 0.991-0.997 for all calibration curves was obtained. The limit of detection was 1.06 µg l-1 (atrazine) and 1.22 µg l-1 (propazine), and the limit of quantitation was 3.54 µg l-1 (atrazine) and 4.07 µg l-1 (propazine). Satisfactory recoveries in the range of 81-108% were determined in milk samples at 5 and 1000 µg l-1, respectively, with low relative standard deviation, n = 3 of 0.301-7.45% in milk matrices. The proposed method is very convenient, rapid, cost-effective and environmentally friendly for food analysis.
The non-ionic silicone surfactant (OFX 0309) has been applied in cloud point extraction for the extraction of triazine herbicides in food samples. Evidence has shown that the non-ionic silicone surfactant demonstrated a good performance as an extractor toward triazine herbicides. In this present study, OFX 0309 surfactant was combined with activated charcoal (AC) due to their valuable properties. Activated charcoal modified with non-ionic silicone surfactant coated with magnetic nanoparticles (AC-OFX MNPs) was synthesized and characterized by FT-IR, VSM, SEM, TEM and BET. This novel material was applied as a magnetic adsorbent for the pre-concentration and separation of triazine herbicides due to hydrophobic interaction between polysiloxane polyether of OFX 0309 surfactant and triazine herbicides. Under optimal conditions, the proposed magnetic solid phase extraction method using AC-OFX MNPs adsorbent was applied to extract triazine herbicides from selected milk and rice samples using high performance liquid chromatography coupled with diode array detector. The validation method revealed a good linearity (1 - 500 μg L-1) with the coefficient of determination (R2) in the range of 0.992-0.998 for the samples. The limits of detection (LOD) of the developed method were 0.04 - 0.05 µg L-1 (milk sample) and 0.02 - 0.05 µg L-1 (rice sample). The limits of quantification (LOQ) were 0.134 - 0.176 µg L-1 (milk sample) and 0.075 - 0.159 µg L-1 (rice sample). The recoveries of the triazine compounds ranged from 81% to 109% in spiked milk samples and from 81% to 111% in spiked rice samples, with relative standard deviations (RSD) values lower than 13.5% and 12.1% for milk and rice samples, respectively. To the best of our knowledge, this is the first study that have investigated the use of magnetic nanoparticles coated activated charcoal modified with OFX 0309 surfactant for pretreatment of triazine herbicides in food samples analysis for simultaneous separation of organic pollutants.