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    Determination of phenytoin at trace levels in domestic wastewater and synthetic urine samples by gas chromatography-mass spectrometry after its preconcentration by simple liquid-phase microextraction
    (Springer, 2024) Bodur, Sezin Erarpat; Ayan, Gizem Nur; Bodur, Suleyman; Gunkara, Omer Tahir; Bakirdere, Sezgin
    This work presents a sensitive and accurate analytical method for the determination of phenytoin at trace levels in domestic wastewater and synthetic urine samples by gas chromatography-mass spectrometry (GC-MS) after the metal sieve-linked double syringe liquid-phase microextraction (MSLDS-LPME) method. A metal sieve was produced in our laboratory in order to disperse water-immiscible extraction solvents into aqueous media. Univariate optimization studies for the selection of proper extraction solvent, extraction solvent volume, mixing cycle, and initial sample volume were carried out. Under the optimum MSLDS-LPME conditions, mass-based dynamic range, limit of quantitation (LOQ), limit of detection (LOD), and percent relative standard deviation (%RSD) for the lowest concentration in calibration plot were figured out to be 100.5-10964.2 mu g kg-1, 150.6 mu g kg-1, 45.2 mu g kg-1, and 9.4%, respectively. Detection power was improved as 187.7-folds by the developed MSLDS-LPME-GC-MS system while enhancement in calibration sensitivity was recorded as 188.0-folds. In the final step of this study, the accuracy and applicability of the proposed system were tested by matrix matching calibration strategy. Percent recovery results for domestic wastewater and synthetic urine samples were calculated as 95.6-110.3% and 91.7-106.6%, respectively. These results proved the accuracy and applicability of the proposed preconcentration method, and the obtained analytical results showed the efficiency of the lab-made metal sieve apparatus.
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    Dispersive solid phase extraction and quadruple isotope dilution-mass spectrometry combination for the accurate and sensitive quantification of capsaicin in pepper, domestic wastewater and human saliva samples by GC-MS system
    (ELSEVIER, 16.12.2024) Bodur, Suleyman; Bodur, Sezin Erarpat; Gursoy, Selim; Ayyildiz, Merve Firat; Kartoglu, Bedrihan; Akbiyik, Hilal; Gunkara, Omer Tahir; Bakirdere, Sezgin
    In the presented study, reduced graphene oxide/Fe3O4 (rGO/Fe3O4) nanocomposites based dispersive solid phase extraction (DSPE) - gas chromatography-mass spectrometry (GC-MS) method was developed for the determination of capsaicin in domestic wastewater (DW), pepper (PP) and human saliva (HS) samples. All important parameters of the DSPE method affected the preconcentration factor were carefully optimized to achieve high signal to noise ratio for the analyte. After the optimization studies, the system analytical performance of DSPEGC-MS system was evaluated using the aqueous standard solution of capsaicin. Limit of detection (LOD), limit of quantitation (LOQ) and dynamic range were figured out to be 0.54 mu g/kg, 1.80 mu g/kg and 2.66 - 487.35 mu g/kg, respectively. Under the optimum experimental conditions, recovery studies were conducted with the spiked DW, PP and HS samples, and percent recovery results were recorded between 52.6 % and 183.6 % via matrix matching calibration strategy. After the implementation of ID4 strategy, percent recovery results for the spiked DW, PP and HS samples were calculated as 98.2 %-99.3 %, 99.7 %-100.7 % and 99.4 %-99.8 %, respectively. In addition, capsaicin content in Sivri (S)-PP, Kil (K)-PP and Samandag (SA)-PP samples were found to be 309.5 +/- 11.8 mg/kg, 873.7 +/- 26.7 mg/kg and 165.3 +/- 5.1 mg/kg via DSPE-GC-ID4-MS method, respectively. As a result, the combination of quadruple isotope dilution (ID4) strategy and the DSPE-GC-MS method were successfully performed to boost the accuracy and precision of developed DSPE-GC-MS method.
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    A powerful combination of liquid chromatography-triple quadrupole mass spectrometry and quadruple isotope dilution strategy for the determination of fenuron at trace levels in river water, stream water and fruit juice samples
    (Academic Press Inc Elsevier Science, 2023) Bodur, Sueleyman; Erarpat, Sezin; Gunkara, Omer Tahir; Bakirdere, Sezgin
    An accurate, sensitive, and rapid analysis methodology for the determination of fenuron at ultratrace levels in river water, stream water and fruit juice samples was developed based on quadruple isotope dilution (ID4) and liquid chromatography-triple quadrupole mass spectrometry (LC-MS/MS) system. Fenuron-d6 as isotopically labelled material (ILM) was synthesized in our laboratory to apply the ID4 method. Optimization studies were performed to find experimental conditions for the separation and detection of fenuron at trace levels. Analytical performance parameters such as limit of detection (LOD), limit of quantitation (LOQ) and linear range were determined by external calibration strategy. LOD and LOQ values for the analyte were found at ppt levels and a wide linear range was obtained in the range of 0.11 - 492.4 & mu;g/kg. Recovery studies were also carried out for water and fruit juice samples to test applicability and accuracy of the developed LC-MS/MS system. ID4 strategy was applied to the selected samples to increase accuracy of the developed method and tolerate high matrix effects for fruit juice samples. According to high percent recoveries and low relative standard deviation values, the developed LC-ID4-MS/MS system was proven as an accurate, precise and sensitive analytical method for the quantification of fenuron at trace levels.
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    Synthesis of Isotopic Labelled Paracetamol Benzoate-d3 and Its Application in the Determination of Paracetamol
    (Wiley-V C H Verlag Gmbh, 2023) Demirel, Rabia; Erarpat, Sezin; Bodur, Suleyman; Gunkara, Omer Tahir; Bakirdere, Sezgin; Turak, Fatma
    This study proposed a precise/accurate analytical method for the paracetamol (PCT) determination in human serum/urine matrices. PCT was simultaneously derivatized and preconcentrated by dispersive liquid-liquid microextraction (DLLME). Benzoyl chloride dissolved in dichloromethane was used as derivatization agent in the extraction solvent. Quadruple isotope dilution (QID) method with three calibration mixtures (A*B-x, x=1,2,3) and one sample mixture (AB) was performed to enhance the method accuracy and precision. In our research laboratory, paracetamol benzoate-d3 (PCT benzoate-d3) was synthesized and used as isotopically labelled substance (B) to conduct QID method. After the combination of QID and DLLME-GC-MS systems, percent recovery results for human serum/urine matrices were found to be 99.3-101.0 % and 98.8-99.9 %, respectively.