Application of hollow fiber-protected liquid-phase microextraction combined with GC-MS in determining Endrin, Chlordane, and Dieldrin in rice samples.

This paper introduces a novel and minimized sample preparation technique based on hollow fiber-protected liquid-phase microextraction that can be used in joint with gas chromatography-mass spectrometry (GC-MS) detection to extract three organochlorine pesticides-Endrin, Chlordane, and Dieldrin-from rice samples. To that end, a single-walled carbon nanotube (SWCNT) and a proper ionic liquid (IL) were ultrasonically dispersed and injected into the lumen of hollow fiber as the extraction phase for preconcentrating and extracting the target analytes from the rice samples. The effects of the type of nanoparticles, ILs, and desorption solvent on the efficiency of extracting the analytes were investigated based on the one-factor-at-a-time (OFAT) approach. In addition, other parameters influencing the extraction procedure were optimized using an experimental design that decreased the number of experiments, reagent consumption, and costs. Under optimized conditions, the limits of detection and quantification in determining mentioned pesticides varied between 0.019-0.029 and 0.064-0.098 ng mL-1, respectively. The calibration graphs to measure Endrin, Chlordane, and Dieldrin were linear over the concentration range of 0.064-13.2, 0.098-16.7, and 0.092-11.4 ng mL-1, respectively. The relative standard deviations for inter-day and intra-day analysis were below 7.06 and 4.75% for the triplicate determination of three organochlorine pesticides. Besides, the relative recoveries and standard deviations of Endrin, Chlordane, and Dieldrin for analyzing several Iranian rice samples were between 86.0-92.9% and 4.5-5.8%, respectively. The results were compared with other similar works in literature, proving that the proposed method is efficient and useful for routine monitoring of organochlorine compounds in food samples.

Simultaneous determination of four antibiotics in human urine and hair samples employing a simple and efficient dispersive micro solid-phase extraction-high performance liquid chromatography.

BACKGROUND: Antibiotics containing azithromycin, amoxicillin, doxycycline, tetracycline, and azithromycin are widely utilized in the treatment of bacterial infections, and their determination in biological samples is critical to evaluate their side effects. METHODS: A dispersive micro solid-phase extraction (DMSPE) as an efficient sample preparation was developed for the simultaneous extraction of the antibiotics in biological samples. For this purpose, chitosan@Fe3O4 nanoparticles were prepared as a green and magnetic sorbent based on a chemical coating of Fe3O4 nanoparticles with chitosan. RESULTS: The sorbent was compared with several sorbents such as ZnO NPs, CuO NPs, and Fe3O4 NPs to extract the antibiotics. In addition, effective factors for antibiotic extraction were evaluated and optimized using a central composite design and one factor at a time. The method has wide linearity in the concentration ranges of 2.1-800.0, 3.5-1000.0, 2.0-800.0, and 2.7-1000.0 µg L-1 with an R-squared higher than 0.9958 for the determination of azithromycin, amoxicillin, doxycycline, and tetracycline, respectively. The limit of detection and limit of quantitation was lower than 1.1 and 3.5 µg L-1, respectively. The relative standard deviations (RSDs) were also lower than 4.90% for the determination of the analytes at a concentration of 20.0 µg L-1. High recoveries in the percentage range of 94.70-106.75%, with RSDs between 4.64 and 5.83%, were obtained to analyze spiked urine and hair samples. CONCLUSIONS: The DMSPE-HPLC-DAD procedure displayed various advantages for determining antibiotics, including simple operation, high recoveries, low sample solution and desorption solvent consumption, high preconcentration factors, proper determination time, and simple and inexpensive method of sorbent preparation.

Application of response surface modeling and chemometrics methods for the determination of Atenolol, Metoprolol and Propranolol in blood sample using dispersive liquid-liquid microextraction combined with HPLC-DAD.

A novel dispersive liquid-liquid microextraction (DLLME) method using ionic liquids (ILs) followed by high-performance liquid chromatography-diode array detector (HPLC-DAD) has been devised to specify Atenolol, Atenolol, Metoprolol and Propranolol in blood real samples. Fourteen effective parameters in DLLME process, including pH of aqueous sample, volume of the dispersion and extraction solvents and ionic strength of donor phase, etc.; were screened using fractional factorial screening methodology (FFSM) based on Placket-Burman design (PBD) and subsequently were optimized by response surface methodology using central composite design (CCD). A mixture of IL (1-butyl-3-methyl imidazolium hexa fluoro phosphate) and disperser solvent (methanol) was quickly injected into the sample solution leading to the formation of the semi cloudy solution. Afterwards, HPLC-DAD was applied to examine the sedimented IL drop. The detection limits (LOD) for all analytes ranges were 0.00268-0.00300 µg L-1. The relative standard deviations (RSDs) for seven experiments were between 3.832% and 4.432% for three target analytes. The proposed method illustrated wide dynamic linear range (DLR, 0.009-1 µg L-1), desirable linearity (R2 ≈ 0.997), high enrichment factors (EF, 313-330) and good relative recoveries (RR, 96-104%). Clear separation and desirable chromatogram was quickly reached without the intervention of the matrix. Besides, a comparison of this method with previous methods indicated that the suggested method is a reproducible, quick and dependable sample pretreatment technique for extraction and determination of pharmaceuticals in blood sample.