| 1. |
- Abdel-Rehim, Abbi, et al.
(författare)
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Advantages of Saliva Sampling in Bioanalysis Using Microextraction by Packed Sorbent and Dried Saliva Spot with LC-MS-MS
- 2014
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Ingår i: LC GC Europe. - 1471-6577. ; 27:10, s. 529-531
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Tidskriftsartikel (refereegranskat)abstract
- Saliva offers a fast and non-invasive sampling matrix for determining drug concentration levels, making it a suitable alternative to plasma and blood. During the analysis of biological samples attention is focused on sample pre-treatment. In addition, liquid chromatography coupled to tandem mass spectrometry (LC-MS-MS) is often the method of choice in bioanalysis because of the good selectivity and good sensitivity of the technique. In this article, two sample handling and sample preparation methods for saliva samples are presented and discussed. The first method is microextraction by packed sorbent (MEPS), and the second method is dried saliva spot (DSS). Both methods were applied for determining the presence of lidocaine in saliva.
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| 2. |
- Abdel-Rehim, Abbi, et al.
(författare)
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Dried saliva spot as a sampling technique for saliva samples
- 2014
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Ingår i: BMC Biomedical chromotography. - : Wiley. - 0269-3879 .- 1099-0801. ; 28:6, s. 875-877
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 3. |
- Abdel-Rehim, Abbi, et al.
(författare)
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Evaluation of microextraction by packed sorbent and micro-liquid chromatography-tandem mass spectrometry as a green approach in bioanalysis
- 2013
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Ingår i: BMC Biomedical chromotography. - : Wiley. - 0269-3879 .- 1099-0801. ; 27:10, s. 1225-1233
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 4. |
- Abdel Rehim, Abbi, et al.
(författare)
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Screening and determination of drugs in human saliva utilizing microextraction by packed sorbent and liquid chromatography-tandem mass spectrometry
- 2013
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Ingår i: BMC Biomedical chromotography. - : Wiley. - 0269-3879 .- 1099-0801. ; 27:9, s. 1188-1191
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 5. |
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| 6. |
- Moein, Mohammad Mahdi, et al.
(författare)
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Microextraction by packed sorbent (MEPS)
- 2015
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Ingår i: TrAC. Trends in analytical chemistry. - : Elsevier BV. - 0165-9936 .- 1879-3142. ; 67, s. 34-44
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Forskningsöversikt (refereegranskat)abstract
- Sample preparation is an important stage in separation and determination of components of interest from complex matrices. Sample preparation strongly influences the reliability and the accuracy of the analysis and the data quality. Recent trends in sample preparation include miniaturization, automation, high-throughput performance, on-line coupling with analytical instruments and low-cost operation using little or no solvent consumption. In the past decade, microextraction by packed sorbent (MEPS) was introduced as a simple, fast, on-line sample-preparation technique. Also, MEPS requires less sample and less solvent. This review gives an outline of the MEPS technique, including fields of application, common formats and sorbents, factors that affect performance, and the major advantages and limitations. Further, we offer and discuss our perspective on the future of MEPS.
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| 7. |
- Moein, Mohammad Mahdi, et al.
(författare)
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On-line determination of sarcosine in biological fluids utilizing dummy molecularly imprinted polymers in microextraction by packed sorbent
- 2015
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Ingår i: Journal of Separation Science. - : Wiley. - 1615-9306 .- 1615-9314. ; 38:5, s. 788-795
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Tidskriftsartikel (refereegranskat)abstract
- Several years ago, sarcosine received attention as a prostate-cancer marker. Prostate cancer is one of the most widespread types of tumor diseases in men. The prostate-specific antigen is normally used as a marker, and it can only be detected in blood with a sensitivity of approximately 80%. In the present study, dummy molecularly imprinted polymers in microextraction by packed sorbent with on-line liquid chromatography coupled to tandem mass spectrometry was used for the determination of sarcosine in human plasma and urine samples. The polymer network glycine was used for the dummy molecularly imprinted polymers. The selectivity of the method was evaluated using similar prostate-cancer biomarkers. In addition, various parameters affecting the extraction performance were investigated. The method limits of detection and quantification in the plasma and urine were 1.0 and 3.0 ng/mL, respectively. The values of the coefficient of determination were over 0.99 for all runs in the studied concentration range (3.0-10 000 ng/mL). The method recovery was 87 and 89% in plasma and urine, respectively. The intraday and interday precisions of sarcosine in the plasma and urine samples were in the ranges of 4.0-7.1, 3.0-6.3, 2.9-4.7, and 5.0-6.7, respectively.
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| 8. |
- Moein, Mohammad Mahdi, et al.
(författare)
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Preparation of monolithic molecularly imprinted polymer sol-gel packed tips for high-throughput bioanalysis : Extraction and quantification of L-tyrosine in human plasma and urine samples utilizing liquid chromatography and tandem mass spectrometry
- 2014
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Ingår i: Journal of chromatography. B. - : Elsevier BV. - 1570-0232 .- 1873-376X. ; 967, s. 168-173
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Tidskriftsartikel (refereegranskat)abstract
- In situ monolithic molecularly imprinted polymer sol-gel packed tips (MMSTs) were prepared and evaluated for the extraction of lung cancer biomarker L-tyrosine (Tyr) from human plasma and urine samples. Several extraction parameters such as the conditioning, washing and elution solutions, pH and time were investigated. The enrichment factor (EF) and extraction recovery (ER) were studied. MMST showed good selectivity and a high extraction recovery, and MMST as a sorbent showed good stability and repeatability. The method validation showed good regression correlation coefficients for plasma and urine samples (R-2 >= 0.996) within the concentration range of 5-1000 and 1-1000 nmol L-1 in plasma and urine samples, respectively. The lower limits of quantification (LLOQ) in the plasma and urine samples were 5 and 1 nmol L-1, respectively. The between-batch precision for Tyr in plasma ranged from 1.0 to 6.0%, and in urine it was from 1.0 to 7.0%. The results show that the developed method has more facility, stability, durability and repeatability compared with previous similar methods. To the best of our knowledge, this is the first study aimed at the selective separation of Tyr as a lung cancer biomarker by MMSTs from biological matrixes and detection by LC/MS/MS.
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| 9. |
- Moein, Mohammad Mahdi, et al.
(författare)
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Recent Applications of Molecularly Imprinted Sol-Gel Methodology in Sample Preparation
- 2019
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Ingår i: Molecules. - : MDPI AG. - 1431-5157 .- 1420-3049. ; 24:16
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Forskningsöversikt (refereegranskat)abstract
- Due to their selectivity and chemical stability, molecularly imprinted polymers have attracted great interest in sample preparation. Imprinted polymers have been applied for the extraction and the enrichment of different sorts of trace analytes in biological and environmental samples before their analysis. Additionally, MIPs are utilized in various sample preparation techniques such as SPE, SPME, SBSE and MEPS. Nevertheless, molecularly imprinted polymers suffer from thermal (stable only up to 150 degrees C) and mechanical stability issues, improper porosity and poor capacity. The sol-gel methodology as a promising alternative to address these limitations allowing the production of sorbents with controlled porosity and higher surface area. Thus the combination of molecularly imprinted technology and sol-gel technology can create influential materials with high selectivity, high capacity and high thermal stability. This work aims to present an overview of molecularly imprinted sol-gel polymerization methods and their applications in analytical and bioanalytical fields.
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| 10. |
- Abdel-Rehim, Abbi, et al.
(författare)
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Protein-ligand binding affinity prediction exploiting sequence constituent homology
- 2023
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Ingår i: Bioinformatics. - 1367-4803 .- 1367-4811. ; 39:8
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Tidskriftsartikel (refereegranskat)abstract
- MOTIVATION: Molecular docking is a commonly used approach for estimating binding conformations and their resultant binding affinities. Machine learning has been successfully deployed to enhance such affinity estimations. Many methods of varying complexity have been developed making use of some or all the spatial and categorical information available in these structures. The evaluation of such methods has mainly been carried out using datasets from PDBbind. Particularly the Comparative Assessment of Scoring Functions (CASF) 2007, 2013, and 2016 datasets with dedicated test sets. This work demonstrates that only a small number of simple descriptors is necessary to efficiently estimate binding affinity for these complexes without the need to know the exact binding conformation of a ligand. RESULTS: The developed approach of using a small number of ligand and protein descriptors in conjunction with gradient boosting trees demonstrates high performance on the CASF datasets. This includes the commonly used benchmark CASF2016 where it appears to perform better than any other approach. This methodology is also useful for datasets where the spatial relationship between the ligand and protein is unknown as demonstrated using a large ChEMBL-derived dataset. AVAILABILITY AND IMPLEMENTATION: Code and data uploaded to https://github.com/abbiAR/PLBAffinity.
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