ABSTRACT An analytical method based on vortex-assisted dispersive liquid-liquid microextraction and gas chromatography-flame ionization detection is presented for the extraction and determination of malondialdehyde) MDA (in blood plasma of human. Various parameters affecting the extraction efficiency such as type and volume of extraction and dispersive solvents, vortex and centrifuge times, volume, ionic strength and pH of the sample solution were evaluated using, one-variable-at-a-time and response surface methodology. In order to optimize the MDA extraction and determination, seven factors in five- levels were used for design of experiments (DOE). Under optimum extraction condition, this method showed linear range of calibration curve between 10–1150 μg L–1. The detection limit of the proposed method was found to be 0.8 μg L–1 with a relative standard deviation better than 5.5% (n=10) for blood serum samples. Enrichment factor was calculated to be 175 fold and the total analysis time including microextraction was about 13 min. The method was successfully applied for the analysis of MDA in blood plasma of human.

ABSTRACT Background: Polycyclic aromatic hydrocarbons (PAHs) are a class of chemicals which have 2 to 7 fused aromatic rings. It is demonstrated that even trace amounts of PAHs are carcinogens, mutagens, and teratogens which can lead to serious risk to the health of humans. According to these facts, determination of PAHs in environmental samples is essential. Methods: In this study, ultrasonic in combination with salt-assisted liquid-liquid extraction was used efficiently for the extraction of PAHs from soil and water samples. In order to evaluate the performance of the proposed method three PAHs, naphthalene, anthracene and pyrene were selected as model analytes. Influential parameters on the extraction efficiency of analytes such as extraction solvent and its volume, salting-out agent and its concentration, ultrasonic time, ultrasonic amplitude and pulse were investigated and optimized. Results: The optimum conditions were as follow; extracting solvent; tetrahydofuran, extracting solvent volume; 3 mL, salting-out agent; sodium acetate, salting-out agent concentration; 20 %w/v, ultrasonic time; 10 s, ultrasonic amplitude; 60% and ultrasonic pulse; 0.5 s. The limits of quantitation for pyrene, naphthalene and anthracene were 1.0, 1.0 and 0.7 ng g−1, respectively. Under the optimum conditions, obtained recoveries in different matrices were in the range of 80.0 to 100.0% with a relative standard deviation better than 7.5%. Conclusions: In the proposed method, after the UAE, sample was exposed to SALLE without need of solid residue removal from the sample. Therefore, extraction steps such as filtration and centrifuge were removed which lead to time saving.

ABSTRACT This work describes a simple photometric determination of iodine concentrations in urine using a dispersive liquid-liquid microextraction method. After digestion of the urine samples with ammonium persulfate, iodide was oxidized with nitrous acid to ICl2– anion at concentrated hydrochloric acid, then Rhodamine B is added and the ion-pair formed was extracted into a mixture of toluene (extracting phase) and ethanol (dispersive solvent) and measured spectrophotometrically. By means of this sensitive method, iodine concentrations can be determined in very small amount of urine specimens (250 μL). The calibration curve showed good linearity within the range of 100-900 μg.L–1 (R2 = 0.985), and the limit of detection for urine was 33.3 μg.L–1. The mean recovery of urine were 95.9-101.2 % with RSD of 2.6-6.6 %. The accuracy and precision of the method was evaluated by comparing to the standard Kolthoff-Sandell method. This suggested method affords a number of advantages, such as being simple, rapid, and inexpensive, with low organic solvent consumption, and is remarkably free from interference effects, rendering it an efficient method for the determination of iodine in urine samples in any routine clinical laboratory.

ABSTRACT A novel 1- naphthalene sulfonic acid (1-NS) molecularly imprinted polymer (MlP)-coated stir bar for sorptive extraction of four naphthalene sulfonates (NSs) from seawater samples was prepared. 1-NS was applied as template molecule. The extraction conditions, including pH, the absorption and desorption times, stirring speed, amount of NaCl and temperature were optimized and the optimum conditions were established as: the absorption and desorption times were fixed respectively at 10 and 15 min, stirring speed was 600 rpm, pH was adjusted to 4.1, amount of NaCl was 1 mol L−1 and extraction process was performed at a temperature of 45 °C. The linear ranges were 5-250 μg L−1 for 3, 6-NDS-1-OH (1-naphthol-3,6-disulfonic acid), 2-NS (2-naphthalene sulfonate) and 1-NS and 10-250 μg L−1 for 5-NH2-1-NS (5-Amino-1-naphthalenesulfonic acid). The detection limits were within the range of 1.20- 2.97 μg L−1. Under the optimum conditions, with the enrichment factor of the NSs were 27, 10, 14 and 7 fold for 2-NS, 1-NS, 3, 6- NDS-1-OH and 5-NH2-1-NS respectively. The RSDs was within 1-9.4%. The method is very suitable for the determination of naphthalene sulfonates (NSs) in seawater samples.

A novel room temperature micro-cloud point extraction procedure using triton X-114 surfactant as extracting phase was developed for preconcentration and extraction of three azo dyes (orange G, methyl orange, and acid red 18) from aqueous samples using molecular absorption spectrophotometry in the visible region. The effects of different parameters such as concentration of surfactant and added salting out reagent (Na2SO4), pH and type of diluting solvent on microextraction were studied and optimized. Under optimum conditions, calibration curves were linear in the range of 2.0-10.0, 0.2-1.0 and 2-12 mg L-1 with the detection limit of 1.6, 0.6 and 111.0 µg L-1 for orange G, methyl orange and acid red 18, respectively. The relative standard deviation was better than 13.12%. The method was applied to the determination of the azo dyes in water samples.

Multi-walled carbon nano-tubes was modified with sodium dodecyl sulfate and used as a solid phase extraction adsorbent for the determination of trace silver in radiological waste samples by flame absorption spectrometry. The effects of pH, initial silver ion concentration, sample flow rate and volume, elution conditions and the amount of adsorbent on the recovery of the analyte were investigated and optimized. The results showed that silver could be fully adsorbed at pH 7.0 and eluted by 5.0 mL 2% thiourea in HNO3 (0.1 mol.L-1). Under the optimized conditions, the adsorption capacity of modified multi-walled carbon nano-tubes was found to be 3.2 mg.g-1 of silver. The detection limit of the proposed method was 350 μg. L-1 for silver with an enrichment factor of 35. The relative standard deviation for ten replicate measurement of 0.5 ug of silver from 700 mL samples was 4.7%. The analytical procedure was successfully applied to the determination of trace silver in a few radiological waste samples with the recoveries between 94% and 105%. Graphite furnace atomic absorption spectrometric technique was also used for the comparison with the suggested method for the determination of the real samples.