| 1. |
- Abdel-Rehim, Mohamed, et al.
(author)
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Microextraction in Packed Syringe Online with Liquid Chromatography-Tandem Mass Spectrometry : Molecularly imprinted polymer as packing material for MEPS in selective extraction of ropivacaine from plasma
- 2006
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In: Journal of Liquid Chromatography & Related Technologies. - : Informa UK Limited. - 1082-6076 .- 1520-572X. ; 29:12, s. 1725-1736
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Journal article (peer-reviewed)abstract
- The excellent performance of a new sample preparation method, microextraction in packed syringe (MEPS), was recently illustrated by online LC‐MS and GS‐MS assays of local anaesthetics in plasma samples. In the method, approximately 1 mg of solid packing material was inserted into a syringe (100–250 µL) as a plug. Sample preparation took place on the packed bed. The new method was easy to use, fully automated, of low cost, and rapid in comparison with previously used methods. This paper presents the use of molecularly imprinted polymers (MIPs) as packing material for higher extraction selectivity. Development and validation of a method for MIP‐MEPS online with LC‐MS‐MS using ropivacaine in plasma as model compound were investigated. A bupivacaine imprinted polymer was used. The method was validated and the standard curves were evaluated by means of quadratic regression and weighted by inverse of the concentration: 1/x for the calibration range 2–2000 nM. The applied polymer could be used more than 100 times before the syringe was discarded. The extraction recovery was 60%. The results showed high correlation coefficients (R 2 >0.999) for all runs. The accuracy, given as a percentage deviation from the nominal concentration values, ranged from -6% to 3%. The precision, given as the relative standard deviation, at three different concentrations (QC samples) was consistently about 3% to 10%. The limit of quantification was 2 nM.
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| 2. |
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| 3. |
- Afifi, Raafat, et al.
(author)
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SPE and HPLC monitoring of 17-β-estradiol in Egyptian aquatic ecosysetms
- 2016
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In: Journal of Liquid Chromatography and Related Technologies. - : Informa UK Limited. - 1082-6076 .- 1520-572X. ; 39:8, s. 428-434
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Journal article (peer-reviewed)abstract
- Solid-phase extraction and HPLC methods are described for monitoring of 17-β-estradiol residues in Egyptian aquatic ecosystems (water, fish, mollusks, sediment, and drinking water) at the Nile River, Suez Canal region, and northeast of Egypt. Molecular imprinted polymer was prepared and used in extraction. High performance liquid chromatography (HPLC) columns used were Supelcosil C18 and Nucleosil C18. The mobile phases used were different combinations of water and acetonitrile. The concentration of 17-β-estradiol in water, aquatic animals, and sediment samples were of 265.13–7988.12 µg/L, 0.503–96.167, and 0.775–11.884 µg/kg, respectively. Marine lake was contained with high levels of 17-β-estradiol (P < 0.05). Similarly, the Nile River downstream showed high levels of 17-β-estradiol. The detected concentrations in mollusks were significantly higher than those detected in fish. Tilapia fish did not show 17-β-estradiol. Contrarily, low concentrations were detected in the rivulet streams supplied by the Nile River. Besides, 17-β-estradiol was also detected in the sediments at low levels. Detection of 17-β-estradiol in the Egyptian ecosystems attracted attention toward heavy reliance on some esterogenic medicinal products in Egypt. The monitoring of 17-β-estradiol in other water bodies was recommended. Besides, the development of methodologies of bioremediation to eliminate 17-β-estradiol from the Egyptian and other water resources of the world was also suggested.
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| 4. |
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| 5. |
- Baranowska, Irena, et al.
(author)
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DEVELOPMENT AND VALIDATION OF RP-HPLC-DAD METHOD FOR DETERMINATION OF NINE DRUGS AND THEIR ELEVEN METABOLITES IN PLASMA AND URINE: PLASMA SAMPLES MEASUREMENTS
- 2013
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In: Journal of Liquid Chromatography & Related Technologies. - : Taylor and Francis: STM, Behavioural Science and Public Health Titles / Taylor and Francis. - 1082-6076 .- 1520-572X. ; 36:12, s. 1597-1615
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Journal article (peer-reviewed)abstract
- A new RP-HPLC-DAD method for determination of nine drugs and eleven metabolites in body fluids was developed. The separation of drugs and metabolites (PAR, SOT, MET, ASP, PRO, NIF, CAR, DEX, KET, PAR-S, PAR-G, MET-H, D-MET, SAL, GENT, PRO-S, D-NIF, ODMC, O-DEX, and KET-G) was achieved using Develosil RP-AQUEOUS-AR5 C30 column in 30min. The obtained MQL values (0.02 mu g/mL0.23 mu g/mL) are suitable for urine/plasma measurements. Correlation coefficient (r(2)) was higher than 0.98 for all analytes. The recoveries ranged from 72.1% to 115.2% (RSD andlt;6.4%). Chromatographic data were obtained with accuracy in the range from 0.3 to 5.6%.
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| 6. |
- Baranowska, Irena, et al.
(author)
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ULTRA HPLC METHOD FOR THE SIMULTANEOUS ANALYSIS OF DRUGS AND FLAVONOIDS IN HUMAN URINE
- 2011
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In: JOURNAL OF LIQUID CHROMATOGRAPHY and RELATED TECHNOLOGIES. - : Taylor and Francis. - 1082-6076 .- 1520-572X. ; 34:6, s. 421-435
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Journal article (peer-reviewed)abstract
- A validated reverse-phase Ultra HPLC method for the simultaneous determination of drugs sotalol, metoprolol, propranolol, carvedilol, salicylic acid, dexamethasone, prednisolone, and ketoprofen and flavonoids: (+/-)-catechin, (-)-epicatechin, rutin, hesperidin, neohesperidin, quercitrin, (+/-)-naringenin, hesperetin in human urine has been developed. Urine samples were pretreated by solid-phase extraction using SDB and C18 cartridges. The extraction efficiencies of each analyte from urine ranged from 76.21% to 101.29%. Gradient separation is achieved by using a Chromolith (R) Fast Gradient Monolithic C18e (50mmx2mm) column and Hypersil Gold (50mmx2.1mm, 1.9 mu m) column, using UV detection to monitor the analytes at 227, 240, 254, and 280nm. The mobile phase consists of mixed 0.05% trifluoroacetic acid in water and acetonitrile in the gradient elution. All sixteen compounds were analyzed within 4min. The LOD and LOQ of drugs and flavonoids are 0.01 mu g/mL and 0.03 mu g/mL; 0.02 mu g/mL and 0.07 mu g/mL, respectively. The developed procedure allows the determination of drugs in urine in concentrations from 0.2 to 40 mu g/mL. The following concentrations of the examined drugs in human urine, belonging to people treated with -blockes, were detected. What is more, an amount of flavonoids occur in urine in higher concentrations than calculated LOD and LOQ. The method has been proved to be precise, accurate, and well suited to the routine determination of all these flavonoid and drug concentrations in human urine samples.
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| 7. |
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| 8. |
- El-Beqqali, Aziza, et al.
(author)
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Microextraction in packed syringe/liquid chromatography/electrospray tandem mass spectrometry for quantification of acebutolol and metoprolol in human plasma and urine samples
- 2007
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In: Journal of Liquid Chromatography & Related Technologies. - : Informa UK Limited. - 1082-6076 .- 1520-572X. ; 30:4, s. 575-586
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Journal article (peer-reviewed)abstract
- The aim of the present investigation was to develop a simple, fast, and sensitive method for the determination of acebutolol and metoprolol in human plasma and urine samples. The determination of acebutolol and metoprolol in plasma and urine was performed using micro extraction in packed syringe (MEPS) as a sample preparation method, online with high performance liquid chromatography and tandem mass spectrometry (LC-MS/MS). In MEPS the sampling sorbent was 1 mg polystyrene polymer, which was inserted in a 250 mu L syringe. The lower limits of quantification (LLOQ) for acebutolol and metoprolol were set to 1.0 ng/mL. The accuracy of quality control samples (QC) varied by +/- 10%, and precision (R.S.D.) had a deviation of 1.4-12% for plasma and urine samples. The calibration curve was obtained within the concentration range 1.0-100 ng/mL in both plasma and urine. The regression correlation coefficients (R-2) for plasma and urine samples were >= 0.999 for all runs. The present method is miniaturized, fully automated, robust, and can be easily used for pharmacokinetic and pharmacodynamic studies of acebutolol and metoprolol.
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| 9. |
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| 10. |
- Sparr Eskilsson, Cecilia, et al.
(author)
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Direct supercritical fluid extraction of alkylphenols from spiked and wastewater samples using extraction cells equipped with hydrophobic membrane-assemblies
- 2004
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In: Journal of Liquid Chromatography & Related Technologies. - 1082-6076. ; 27:18, s. 2871-2888
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Journal article (peer-reviewed)abstract
- Akylphenols (4-nonylphenol, 4-(1,1,3,3-tetramethylbutyl)-phenol and 2,6-bis(1,1-dimethylethyl)-4-ethylphenol) have been directly extracted from water samples using neat supercritical carbon dioxide and collected on an octadecyl silica (ODS) solid phase trap. The extraction cells were equipped with home-built assemblies containing hydrophobic membranes. The assemblies were inserted at each end of the extraction cell to maintain the water sample inside the extraction cell. In this case, no sample pretreatment step, such as freeze-drying or solid phase extraction (SPE) of the water samples, was needed prior to the supercritical fluid extraction (SFE). Distilled water, spiked with an alkylphenol standard solution at a level of 25 mg/L, was used as a model sample to investigate extraction efficiency as well as collection capability. To obtain quantitative recoveries, a fractionated extraction/clution procedure was adopted. The alkylphenols were finally determined in a leachate water sample and in an industrial effluent sample, where the levels were in the range of 0.2-10 mg/L.
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