Electrophoretic deposition of ordered mesoporous carbon nitride on a stainless steel wire as a high-performance solid phase microextraction coating.

An electrophoretic deposition approach was developed to fabricate a robust ordered mesoporous carbon nitride (MCN) coating for solid-phase microextraction. The large surface area, uniform pore diameter, in-built N-rich functional groups, and electron delocalization properties of MCN make it a promising adsorbent for SPME by π-π, hydrogen bonding and hydrophobic interactions between analytes and MCN.

Determination of fentanyl in biological and water samples using single-drop liquid-liquid-liquid microextraction coupled with high-performance liquid chromatography.

A single-drop liquid-liquid-liquid microextraction (LLLME) method coupled with high-performance liquid chromatography (HPLC) was developed for the determination of fentanyl in biological (plasma and urine) and wastewater samples. Fentanyl is a potent synthetic narcotic analgesic administered in the form of a transdermal patch for the management of chronic pain. Fentanyl was extracted from 0.01 M NaOH solution (donor phase) into a thin layer of organic phase (100 muL), then back-extracted into 5 muL of the acidic acceptor microdrop (1 x 10(-3)M HClO(4)) immersed in the organic membrane from the tip of a 25-muL HPLC syringe. After the extraction, the microdrop was withdrawn into the syringe and injected directly into a HPLC system for analysis. The parameters influencing the extraction efficiency including the organic solvent and its volume, acceptor microdrop volume, composition of the donor and acceptor phases, stirring rate, temperature, salt addition and pre- and back-extraction times were investigated and optimized. At the most appropriate conditions (100 muL of n-octane, 3.6 mL of the donor phase maintained at 0.01 M NaOH, 5 muL of 1 x 10(-3)M HClO(4) as the acceptor microdrop, stirring rate of 1000 rpm for pre-extraction and 700 rpm for back-extraction, 30 degrees C, no salt addition, 30 min for pre-extraction and 20 min for back-extraction), an enrichment factor (EF) of 355 was obtained. The limit of detection (LOD) was 0.1 ngmL(-1) (based on S/N=3) and intra- and inter-day relative standard deviations less than 9% were obtained. The calibration graph was linear within the range of 0.5-1000 ngmL(-1) with the correlation coefficient (r) of 0.9999. Finally, the feasibility of the proposed method was evaluated by extraction and determination of fentanyl in plasma, urine and wastewater samples and satisfactory results were obtained.

Determination of tramadol in human plasma and urine samples using liquid phase microextraction with back extraction combined with high performance liquid chromatography.

Liquid phase microextraction by back extraction (LPME-BE) combined with high performance liquid chromatography (HPLC)-fluorescence detection was developed for the determination of tramadol in human plasma. Tramadol was extracted from 2 mL of basic sample solution (donor phase) with pH 11.5 through a micro liter-size organic solvent phase (100 microL n-octane) for 25 min and finally into a 3.5 microL acidic aqueous acceptor microdrop with pH 2.5 suspended in the organic phase from the tip of a HPLC microsyringe needle for 15 min with the stirring rate of 1250 rpm. After extraction for a period of time, the microdrop was taken back into the syringe and injected into HPLC. Effected the experimental parameters such as the nature of the extracting solvent and its volume, sample temperature, stirring rate, volume of the acceptor phase, pH and extraction time on LPME-BE efficiency was investigated. At the optimized condition, enrichment factor of 366 and detection limit (LOD) of 0.12 microg L(-1) were obtained. The calibration curve was linear (r=0.999) in the concentration range of 0.3-130 microg L(-1). Within-day relative standard deviation RSD (S/N=3) and between-day RSD were 3.16% and 6.29%, respectively. The method was successfully applied to determine the concentration of tramadol in the plasma and urine samples and satisfactory results were obtained.

Solid-phase extraction, separation, and visible spectrophotometric determination of trace amounts of iron in water samples.

A simple and reliable method is presented for the rapid extraction, separation, preconcentration, and determination of iron as its bathophenanthroline complex by the use of octadecylsilica membrane disks and spectrophotometry. We evaluted extraction efficiency, the influence of sample matrix, type and optimum amount of extractant, flow rates of sample solution and eluent, pH, amounts of bathophenanthroline and hydroxylamine hydrochloride, breakthrough volume, and limit of detection. We also studied the effects of various cationic interferences on percent recovery of iron. Complete elution of the complex from disks was obtained with a minimal amount of solvent. The limit of detection of the proposed method is 0.080 ppb. The method was applied to the recovery and determination of iron in natural waters.

Solid-phase extraction of ultratrace uranium(VI) in natural waters using octadecyl silica membrane disks modified by tri-n-octylphosphine oxide and its spectrophotometric determination with dibenzoylmethane.

A simple and reliable method for rapid extraction and determination of uranium in natural waters using octadecyl-bonded silica membrane disks modified with tri-n-octylphosphine oxide (TOPO) and spectrophotometry with dibenzoylmethane is presented. Extraction efficiency and the influence of sample matrix, type, and optimum amount of extractant, flow rates, and type and minimum amount of organic eluent were evaluated. The maximal capacity of the membrane disks modified by 50 mg of TOPO was found to be 4033 micrograms of uranium. The limit of detection of the proposed method is 100 ng/1000 mL. The method was applied to the extraction and determination of uranium in natural waters.

Solubilities of some recently synthesized 1,8-dihydroxy-9,10-anthraquinone derivatives in supercritical carbon dioxide.

The solubility of four recently synthesized 1,8-dihydroxy-9,10-anthraquinone derivatives, as potential complexing agents in some extraction and membrane transport experiments, have been measured in supercritical carbon dioxide. The measurements were carried out in the pressure range 120-400 atm at temperatures 35, 45, 55, 65, and 75 degrees C. The measured solubilities were correlated using the model proposed by Chrastil. The calculated results show good agreement with the experimental data.

Solid-phase extraction and spectrophotometric determination of trace amounts of copper in water samples.

A simple method for rapid and selective extraction, preconcentration and determination of copper as it's neocuproine complex by using octadecylsilica membrane disks and spectrophotometry is presented. Extraction efficiency and the influence of flow rates of sample solution and eluent, pH, amount of neocuproine and hydroxylamine hydrochloride, type and least amount of eluent for elution of copper complex from disks, break through volume and limit of detection were evaluated. Also the effects of various cationic interferences on percent recovery of copper were studied. Extraction efficiencies >99% were obtained by elution of the disks with minimal amount of solvent. The limit of detection of the proposed method is 0.12 ppb. The method was applied to the recovery and determination of copper in different water samples.

Extraction and determination of crown ethers from water samples using a membrane disk and gas chromatography.

A method for rapid extraction and determination of some crown ethers in aqueous matrices using octadecyl-bonded silica membrane disks and gas chromatography is presented. Extraction efficiency and the influence of vacuum pressure. pH, and type and least amount of eluting solvent used to extract the crown ethers from the membrane disks were evaluated. Extraction efficiencies > 95% were obtained for benzo-15-crown-5, benzo-18-crown-6 and dicyclohexyl-18-crown-6 using 5 ml of acetonitrile as eluting solvent. The limit of detection of the proposed method for the determination of the crown ethers is reported.