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  • 1.
    Abdel Rehim, Abbi
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Abdel Rehim, Mohamed
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Screening and determination of drugs in human saliva utilizing microextraction by packed sorbent and liquid chromatography-tandem mass spectrometry2013In: BMC Biomedical chromotography, ISSN 0269-3879, E-ISSN 1099-0801, Vol. 27, no 9, p. 1188-1191Article in journal (Refereed)
    Abstract [en]

    This study presents a new method for collecting and handling saliva samples using an automated analytical microsyringe and microextraction by packed syringe (MEPS). The screening and determination of lidocaine in human saliva samples utilizing MEPS and liquid chromatography-tandem mass spectrometry (LC-MS/MS) were carried out. An exact volume of saliva could be collected. The MEPS C-8-cartridge could be used for 50 extractions before it was discarded. The extraction recovery was about 60%. The pharmacokinetic curve of lidocaine in saliva using MEPS-LC-MS/MS is reported.

  • 2. Abdel-Rehim, Abbi
    et al.
    Abdel-Rehim, Mohamed
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Dried saliva spot as a sampling technique for saliva samples2014In: BMC Biomedical chromotography, ISSN 0269-3879, E-ISSN 1099-0801, Vol. 28, no 6, p. 875-877Article in journal (Refereed)
    Abstract [en]

    For the first time, dried saliva spot (DSS) was used as a sampling technique for saliva samples. In the DSS technique 50 L of saliva was collected on filter paper and the saliva was then extracted with an organic solvent. The local anesthetic lidocaine was used as a model compound, which was determined in the DSS using liquid chromatography and mass spectrometry. The results obtained for the determination of lidocaine in saliva using DSS were compared with those from a previous study using a microextraction by packed sorbent syringe as the sampling method for saliva. This study shows that DSS can be used for the analysis of saliva samples. The method is promising and very easy in terms of sampling and extraction procedures. The results from this study are in good agreement with those from our previous work on the determination of lidocaine in saliva. DSS can open a new dimension in the saliva handling process in terms of sampling, storing and transport.

  • 3.
    Abdel-Rehim, Abbi
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Abdel-Rehim, Mohamed
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Evaluation of microextraction by packed sorbent and micro-liquid chromatography-tandem mass spectrometry as a green approach in bioanalysis2013In: BMC Biomedical chromotography, ISSN 0269-3879, E-ISSN 1099-0801, Vol. 27, no 10, p. 1225-1233Article in journal (Refereed)
    Abstract [en]

    In this study the use of micro-liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) was investigated in routine bioanalysis application for separation and quantification of pro-drug AZD6319 (developed for aldezheimer treatment). Microextraction by packed sorbent (MEPS) was used as sample clean-up method. The focus of this study was put on the evaluation of the usability of smaller column diameters such as 1.0 and 0.3mm instead of 2.1mm in bioanalysis application to reduce solvent consumption and sample volumes. Solvent consumption was reduced by 80% when a 1.0mm column was used compared with 2.1mm column. Robustness of the micro-columns in terms of accuracy and precision was investigated. The application of LC-MS/MS for the quantitative analysis of AZD6319 in plasma samples showed good selectivity, accuracy and precision. The coefficients of determination (R-2) were >0.998 for all runs using plasma samples on the studied micro-columns. The inter-day accuracy values for quality control samples ranged from 99 to 103% and from 96 to 105% for 0.3x50mm and 1.0x50mm columns, respectively. The inter-day precision values ranged from 4.0 to 9.0% and from 4.0 to 8.0% for 0.3x50 and 1.0x50mm columns, respectively. In addition the sensitivity was increased by three times using a 1.0mm column compared with 2.1mm. Furthermore, robustness of the micro-columns from different manufacturers was investigated.

  • 4.
    Ashri, Nadia Y.
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Daryanavard, Mosayeb
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Abdel-Rehim, Mohamed
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    micMicroextraction by packed sorbent and liquid chromatography-tandem mass spectrometry as a tool for quantification of peptides in plasma samples: determination of sensory neuron-specific receptors agonist BAM8-22 and antagonist BAM22-8 in plasma samples2013In: BMC Biomedical chromotography, ISSN 0269-3879, E-ISSN 1099-0801, Vol. 27, no 3, p. 396-403Article in journal (Refereed)
    Abstract [en]

    Microextraction by packed sorbent (MEPS) is a miniaturized, solid-phase extraction (SPE) technique that works online with gas chromatography (GC) and liquid chromatography (LC). Not only is the automation process with MEPS advantageous, but the much smaller volumes of the samples, solvents and dead space in the system also provide other significant advantages such as the speed and the simplicity of the sample preparation process. In this study MEPS has been evaluated for quantification of sensory neuron-specific receptors agonist (BAM8-22). Owing to the instability of BAMs, the focus was on fast extraction and determination of the peptide online using LC-MS/MS. Sorbents such as C2, C8 and ENV+ (hydroxylated polystyrenedivinylbenzene copolymer) were investigated in the present study. MEPS-C8 gave the best results compared with C2 and ENV and it was used for the method validation. The calibration curve was obtained within the concentration range of 20.03045nmol/L in plasma. The regression correlation coefficients for plasma samples were 0.99 for all runs (n=6). The between-batch accuracy and precision for BAM8-22 ranged from 13 to 2.0% and from 4.0 to 14%, respectively. Additionally, the accuracy and precision for BAM22-8 ranged from 13 to 7.0% and from 3.0 to 12%, respectively. The present method was used for pharmacokinetic studies for BAMs in plasma samples.

  • 5.
    Daryanavard, Seyed
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Jeppsson-Dadoun, Amin
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Andersson, Lars I.
    Hashemi, Mahdi
    Colmsjö, Anders
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Abdel-Rehim, Mohamed
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Molecularly imprinted polymer in microextraction by packed sorbent for the simultaneous determination of local anesthetics: lidocaine, ropivacaine, mepivacaine and bupivacaine in plasma and urine samples2013In: BMC Biomedical chromotography, ISSN 0269-3879, E-ISSN 1099-0801, Vol. 27, no 11, p. 1418-1488Article in journal (Refereed)
    Abstract [en]

    This study presents the use of molecularly imprinted polymer (MIP) as packing material for microextraction by packed syringe (MEPS) to achieve higher extraction selectivity. Pentycaine was used as template for MIP. Development and validation of the determination of lidocaine, ropivacaine, mepivacaine and bupivacaine in human plasma and urine samples utilizing MIP-MEPS and liquid chromatography–tandem mass spectrometry (LC-MS/MS) were carried out. The MEPS MIP-cartridge could be used for 100 extractions before it was discarded. The extraction recovery ranged from 60 to 80%. The correlation coefficients values were >0.999 for all assays using lidocaine, ropivacaine, mepivacaine and bupivacaine in the calibration range 5–2000 nmol/L. The accuracy of the studied compounds, given as a percentage variation from the nominal concentration values, ranged from -4.9 to 8.4% using plasma and urine samples. The between-batch precision, given as the relative standard deviation, at three different concentrations (quality control samples) was ranged from −4.7 to 14.0% and from 1.8 to 12.7% in plasma and urine, respectively. The lower limit of quantification and limit of detection of the studied substances were 5.0 and 1.0 nm, respectively

  • 6.
    Elmongy, Hatem
    et al.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry. Damanhour University, Egypt.
    Ahmed, Hytham
    Wahbi, Abdel-Aziz
    Amini, Ahmad
    Colmsjö, Anders
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Abdel-Rehim, Mohamed
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Determination of metoprolol enantiomers in human plasma and saliva samples utilizing microextraction by packed sorbent and liquid chromatography-tandem mass spectrometry2016In: BMC Biomedical chromotography, ISSN 0269-3879, E-ISSN 1099-0801, Vol. 30, no 8, p. 1309-1317Article in journal (Refereed)
    Abstract [en]

    A sensitive, accurate and reliable bioanalytical method for the enantioselective determination of metoprolol in plasma and saliva samples utilizing liquid chromatography-electrospray ionization tandem mass spectrometry was developed and validated. Human plasma and saliva samples were pretreated by microextraction by packed sorbent (MEPS) prior to analysis. A new MEPS syringe form with two inputs was used. Metoprolol enantiomers and internal standard pentycaine (IS) were eluted from MEPS sorbent using isopropanol after removal of matrix interferences using aliquots of 5% methanol in water. Complete separation of metoprolol enantiomers was achieved on a Cellulose-SB column (150x4.6mm, 5m) using isocratic elution with mobile phase 0.1% ammonium hydroxide in hexane-isopropanol (80:20, v/v) with a flow rate of 0.8mL/min. A post-column solvent-assisted ionization was applied to enhance metoprolol ionization signal in positive mode monitoring (+ES) using 0.5% formic acid in isopropanol at a flow rate of 0.2mL/min. The total chromatographic run time was 10min for each injection. The detection of metoprolol in plasma and saliva samples was performed using triple quadrupole tandem mass spectrometer in +ES under the following mass transitions: m/z 268.0872.09 for metoprolol and m/z 303.3154.3 for IS. The linearity range was 2.5-500ng/mL for both R- and S-metoprolol in plasma and saliva. The limits of detection and quantitation for both enantiomers were 0.5 and 2.5ng/mL respectively, in both matrices (plasma and saliva). The intra- and inter-day precisions were presented in terms of RSD values for replicate analysis of quality control samples and were <5%; the accuracy of determinations varied from 96 to 99%. The method was able to determine the therapeutic levels of metoprolol enantiomers in both human plasma and saliva samples successfully, which can aid in therapeutic drug monitoring in clinical laboratories.

  • 7. Pereira, Jorge
    et al.
    Camara, Jose S.
    Colmsjö, Anders
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Abdel-Rehim, Mohamed
    Stockholm University, Faculty of Science, Department of Analytical Chemistry. National Research Center, Egypt.
    Microextraction by packed sorbent: an emerging, selective and high-throughput extraction technique in bioanalysis2014In: BMC Biomedical chromotography, ISSN 0269-3879, E-ISSN 1099-0801, Vol. 28, no 6, p. 839-847Article in journal (Refereed)
    Abstract [en]

    Sample preparation is an important analytical step regarding the isolation and concentration of desired components from complex matrices and greatly influences their reliable and accurate analysis and data quality. It is the most labor-intensive and error-prone process in analytical methodology and, therefore, may influence the analytical performance of the target analytes quantification. Many conventional sample preparation methods are relatively complicated, involving time-consuming procedures and requiring large volumes of organic solvents. Recent trends in sample preparation include miniaturization, automation, high-throughput performance, on-line coupling with analytical instruments and low-cost operation through extremely low volume or no solvent consumption. Micro-extraction techniques, such as micro-extraction by packed sorbent (MEPS), have these advantages over the traditional techniques. This paper gives an overview of MEPS technique, including the role of sample preparation in bioanalysis, the MEPS description namely MEPS formats (on- and off-line), sorbents, experimental and protocols, factors that affect the MEPS performance, and the major advantages and limitations of MEPS compared with other sample preparation techniques. We also summarize MEPS recent applications in bioanalysis.

  • 8.
    Skoglund, Christina
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry. Lantmännen Agroetanol.
    Bassyouni, Fatma
    Stockholm University, Faculty of Science, Department of Analytical Chemistry. Centre of Excellence for Advanced Sciences, National Research Centre, Dokki, Cairo, Egypt.
    Abdel-Rehim, Mohamed
    Stockholm University, Faculty of Science, Department of Analytical Chemistry. Centre of Excellence for Advanced Sciences, National Research Centre, Dokki, Cairo, Egypt.
    Monolithic packed 96-tips set for high-throughput sample preparation: determination of cyclophosphamide and busulfan in whole blood samples by monolithic packed 96-tips and LC-MS2013In: BMC Biomedical chromotography, ISSN 0269-3879, E-ISSN 1099-0801, Vol. 27, no 6, p. 714-719Article in journal (Refereed)
    Abstract [en]

    A monolithic methacrylate packed 96-tips device was used for the extraction of the busulfan and cyclophosphamide in whole blood samples. Using a packed 96-tips set, a 96-well plate could be handled in about 2min. The key aspect of the monolithic phase is that monolithic material can offer both good extraction capacity and low-back-pressure properties. The validation of the methodology showed that the accuracy values of quality-control samples were between 99 and 113% for busulfan, and between 103 and 110% for cyclophosphamide. The inter-day precision ranged from 7.0 to 12% for busulfan and from 13 to 16% for cyclophosphamide. The standard calibration curves were obtained within the concentration range 52000nm for busulfan and from 10 to 5000nm for cyclophosphamide in blood samples. The coefficients of determination were 0.99.

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