Dispersive Solid Phase Extraction Using Magnetic NanoparticlesPerformed in a Narrow-Bored Tube for Extraction of Atorvastatin,Losartan, and Valsartan in Plasma

Purpose: In this investigation, a new version of magnetic solid phase extraction (MSPE) performedin a narrow–bore tube has been proposed. In this study, hydrophobic octyl (C8) functionalizedFe3O4 magnetic nanoparticles (MNPs) stabilized by SiOH groups (Fe3O4@SiO2@C8) are used asmagnetic nano–sorbents for the extraction of cardiovascular drugs from human plasma prior totheir determination by high performance liquid chromatography–photodiode array detection.Methods: After precipitation of the plasma proteins, the supernatant is diluted with deionizedwater and filled into the narrow–bore tube. Then mg–level of the sorbent is added into the tube.The sorbent is dispersed and moved down through the solution instead of passing the solutionfrom the cartridge. Using an external magnet, the collected nano–sorbents at the bottom of thetube are transferred on top of the solution and released to move down through the solution forthree times to increase the extraction efficiency.Results: The linearity of the assay was ranging from 0.4–500 mg mL-1. The limits of detectionand quantification of the method were obtained in the ranges of 0.05–0.07 and 0.16–0.24 mgL-1, respectively. The extraction recoveries were obtained in the range of 31–49%. Intra– andinter–day precisions were calculated and obtained in the ranges of 5–8 and 7%–9% for 0.5 mgL-1 of each analyte, and 5–6 and 6%–8% for 2 mg L-1 of each analyte, respectively.Conclusion: The proposed method was successfully used in determination of the studied drugsin patient’s plasmas

A Review on Application of Microextraction Techniques for Analysis of Chemical Compounds and Metal Ions in Foodstuffs

Foodstuffs analysis is very important due to population growth and increasing consumer demand for safety and nutritional excellence. The Analysis of different compounds in foodstuffs is so difficult without using sample preparation techniques. Traditional techniques require large amounts of toxic organic solvents. As a result, they are not only expensive but also environmentally unfriendly and they generate a considerable amount of waste. Nowadays efforts are being focused on development of microextraction techniques. Different microextraction techniques such as solid phase microextraction (SPME), stir bar sorptive extraction (SBSE), and liquid phase microextraction (LPME) have found an important place in sample preparation because of their inherent advantages over the conventional procedures. In particular, they have been applied with successfully for the analysis of food samples despite their complexity. The review discusses different microextraction approaches used in analysis of chemical compounds and metal ions in foodstuffs. It summarizes the application of microextraction techniques in food analysis in details as possible

Determination of tricyclic antidepressants in human urine samples by the three-step sample pretreatment followed by HPLC-UV analysis

In this work, an efficient sample pretreatment method has been developed by combining salt induced– homogenous liquid–liquid extraction, dispersive solid phase extraction, and dispersive liquid–liquid microextraction based on the solidification of floating organic droplet for the extraction of some widely used tricyclic antidepressant (TCA) drugs (nortriptyline, amitriptyline, desipramine, clomipramine, and imipramine) in human urine samples before their determination by high performance liquid chromatography–ultraviolet detection. In brief, the target analytes are first isolated from urine samples into acetonitrile (ACN) separated by adding a salt. Then the obtained ACN phase is treated with a mixture of appropriate sorbents to remove interferences. Afterward, the purified ACN is mixed with menthol as an extractant and rapidly injected into alkaline HPLC–grade water as a preconcentration step. Next, the obtained solution is placed in an ice bath and menthol collects on top of the solution after solidification. The solidified drop is then withdrawn and injected into separation system after dissolving in 10 μL ACN. Under the optimum experimental conditions, extraction recoveries and enrichment factors of the selected drugs ranged from 69–84 % and 345–420, respectively. The limits of detection and quantification were obtained at the ranges of 0.22–0.31, and 0.71–1.1 μg L–1, respectively. The relative standard deviations of the proposed method were ≤ 6 % for intra– (n=6) and inter–day (n=4) precisions at a concentration of 10 μg L–1 (each drug). Finally, the suggested approach was applied to determine of TCA drugs in different patients' urine samples. The method could be applied in further TCAs pharmacokinetic and forensic studies

Solvent exchange using hollow fiber prior to separation and determination of some antioxidants by high performance liquid chromatography

This study presents a simple and rapid solvent exchange procedure using a hollow fiber. Antioxidants (Irganox 1010, Irganox 1076 and Irgafos 168) and solvents such as tetrahydrofuran (THF), carbon tetrachloride and toluene were selected as model compounds and sample solvents, respectively. After injection of the sample solution into the hollow fiber and solvent evaporation, the precipitated analytes in lumen and pores of the fiber were washed with methanol (the mobile phase for separation and determination by HPLC-diode array detection) and good chromatographic peaks were obtained. The effect of different parameters such as fiber length, volumes of sample and washing solvents were investigated and the optimum conditions were selected. The repeatability of the method was tested and it was found that the relative standard deviation (R.S.D.) was less than 10% for all analytes. Also enrichment factors of 3.03, 2.21 and 1.19 times were obtained for Irganox 1010, Irganox 1076 and Irgafos 168, respectively, when 200 mu L sample and 50 mu L methanol (washing solvent) were used. (c) 2007 Elsevier BX All rights reserved

Dispersive liquid-liquid microextraction followed by high-performance liquid chromatography-diode array detection as an efficient and sensitive technique for determination of antioxidants

Dispersive liquid-liquid microextraction (DLLME) and high performance liquid chromatography-diode array detection (HPLC-DAD) was presented for extraction and determination of Irganox 1010, Irganox 1076 and Irgafos 168 (antioxidants) in aqueous samples. Carbon tetrachloride at microliter volume level and acetonitrile were used as extraction and dispersive solvents, respectively. The main advantages of method are high speed, high enrichment factor, high recovery, good repeatability and extraction solvent volume at mu L level. Limit of detection for analytes is between 3 and 7 ng mL(-1). One variable at a time optimization and response surface modeling were used to obtain optimum conditions for microextraction procedure and nearly same experimental conditions were obtained using both optimization methods. Recoveries in the ranges 78-86% and 84-110% were obtained by one variable at a time and response surface modeling, respectively. Using tap water and packed water as matrices do not show any detrimental effect on the extraction recoveries and enrichment factors of analytes. (C) 2007 Elsevier B.V. All rights reserved

Saponification then GC for determination of Irganox 1010 and Irganox 1076 in a polymer matrix

A gas chromatographic method has been established for determination of Irganox 10 10 and 1076 after saponification. The analytes were saponified with methanolic potassium hydroxide, acidified with hydrochloric acid, and the solvent was removed by rotary evaporation. The dry residue was dissolved in xylene and analyzed by GC with flame-ionization detector (FID). Compounds were separated on a polar (Carbowax 20 M) capillary column and nitrogen was used as carrier gas and make-up gas. This method has a relatively large linear dynamic range, 50-3,000 and 100-1,600 mg L-1 for Irganox 1010 and 1076, respectively, and limits of detection (LOD) were 20 and 40 mg L-1, respectively. The effect of conditions such as saponification temperature, and concentration and volume of potassium hydroxide were studied

Determination of 2-Octanone in Biological Samples Using Liquid–Liquid Microextractions Followed by Gas Chromatography–Flame Ionization Detectio

Background: Analysis of chemicals in biological fluids is required in many areas of medical sciences. Rapid, highly efficient, and reliable dispersive and air assisted liquid–liquid microextraction methods followed by gas chromatography-flame ionization detection were developed for the extraction, preconcentration, and determination of 2-octanone in human plasma and urine samples. Methods: Proteins of plasma samples are precipitated by adding methanol and urine sample is diluted with water prior to performing the microextraction procedure. Fine organic solvent droplets are formed by repeated suction and injection of the mixture of sample solution and extraction solvent into a test tube with a glass syringe. After extraction, phase separation is performed by centrifuging and the enriched analyte in the sedimented organic phase is determined by the separation system. The main factors influencing the extraction efficiency including extraction solvent type and volume, salt addition, pH, and extraction times are investigated. Results: Under the optimized conditions, the proposed method showed good precision (relative standard deviation less than 7%). Limit of detection and lower limit of quantification for 2-octanone were obtained in the range of 0.1–0.5 µg mL−1. The linear ranges were 0.5-500 and 0.5-200 µg mL−1 in plasma and urine, respectively (r2 ≥ 0.9995). Enrichment factors were in the range of 13-37. Good recoveries (55–86%) were obtained for the spiked samples. Conclusion: Preconcentration methods coupled with GC analysis were developed and could be used to monitor 2-octanone in biological samples

Optimization and application of homogeneous liquid-liquid extraction in preconcentration of copper (II) in a ternary solvent system

In this study a homogeneous liquid-liquid extraction based on the Ph-dependent phase-separation process was investigated using a ternary solvent system (water-acetic acid-chloroform) for the preconcentration of Cu2+ ions. 8-Hydroxy quinoline was used as the chelating agent prior to its extraction. Flame atomic absorption spectro photometry using acetylene-air flame was used for the quantitation of analyte after preconcentration. The effect of various experimental parameters in extraction step was investigated using two optimization methods, one variable at a time and central composite design. The experimental design was done at five levels of operating parameters. Nearly the same optimized results were obtained using both methods: sample size, 5 mL: volume of NaOH 10 M, 2 mL; chloroform volume, 300 mu L; 8-hydroxy quinoline concentration more than 0.01 M and Salt amount did not affect the extraction significantly. Under the optimum conditions the calibration graph was linear over the range 10-2000 mu g L-1. The relative standard deviation was 7.6% for six repeated determinations (C = 500 mu g L-1). Furthermore, the limit of detection (S/N = 3) and limit of quantification (S/N = 10) of the method were obtained as 1.74 and 6 mu g L-1, respectively. (C) 2008 Elsevier B.V. All rights reserved