Browsing by Issue Date, starting with "2010-03-02"
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- Determination of cyclophosphamide in human urine by HPLC coupled to tandem mass spectrometryPublication . Marahatta, Anu; Wasik, Agata Kot; Wasik, AndrzejBiological samples urine are much more complex due to presence of proteins, salts, acids, bases and various organic compounds with similar chemistry to analytes of interest. As a result, the extraction methods for biological samples have been difficult. The main task was to remove maximum interfering substance from urine matrix and conversion of analytes into a more suitable form for injection. Therefore, optimization of SPE method was done by changing different parameter such as different type and amount of sorbent, composition and volume of elution, washing solvent. The use of 24 well SPE plate for matrix purification significantly allows the use of small urine and solvent volumes, reduces the sample preparation time and ensures a high throughput, thus allowing the routine biological monitoring of CP as indices of human exposures. In order to investigate the effectiveness of the SPE method tests were repeated on Strata-X cartridge and method showed good recovery (above 75 %) of CP. After optimizing SPE method, CP separation conditions of the HPLC-MS/MS analysis was achieve by changing different parameter such as suitable mobile phase and its composition, flow rate, scan type, polarity. The LC separation was performed on Lichrocart® 100 RP-18 column (125 4 mm, particle size of 5 μm) with 1 mM formic acid with ammonia buffer pH 3 and methanol using gradient program at a flow rate 1 mL/min with total run time 15 min. A reversed phase HPLC system was interfaced with an ESI source coupled to tandem mass spectrometry. The triple quadrupole mass spectrometer was operated in positive ion mode and MRM was used for analysis of CP. LOD and LOQ were 0.27 ng/mL and 0.54 ng/mL. A sensitive, specific and accurate HPLC/MS/MS has been developed for monitoring CP in urine samples. The use of reversed phase HPLC coupled to tandem mass spectrometry has facilitated the analysis of CP in short retention time. Fifteen urine samples were collected from medical personnel of Medical University of Gdansk, who were exposed with CP during their work in pharmacy. SPE-HPLC-MS/MS method was applied for the analysis of health workers and all urine samples from university workers has CP below analytical limit of detection.
- Applicability of head space solid phase microextraction (HS-SPME) with polyethylene glycol (PEG) fibre for GC-MS determination of volatile fatty acids in aqueous samplesPublication . Faniband, Moosa Hassan; Zygmunt, Bogdan; Banel, AnnaA method consisting of head-space solid phase micro extraction (HS-SPME) followed by gas chromatography coupled with mass spectrometry (GC-MS) was developed for determination of volatile fatty acids in wastewater. A new fibre polyethylene glycol (PEG) was evaluated for the sample preparation. This fibre is designed to show high sample capacity, faster mass transfer during extraction, shorter equilibrium times and faster desorption process. The developed method showed good sensitivity with comparable limit of detection (LOD) and limit of quantitation (LOQ) values. The selection of various parameters included extraction time, extraction temperature, sample volume and desorption conditions. The experimental results showed low detection limits ranging between 0.01 mg/L to 0.06 mg/L for different acids. The new fibre was found to be efficient towards acetic and propionic acid.
- Determination of volatile fatty acids in municipal wastewater by gas chromatography-mass spectrometry preceded by headspace- solid phase microextraction with PDMS-CAR fibrePublication . Pokhrel, Teeka Ram; Zygmunt, Bogdan; Banel, AnnaAn analytical procedure based on headspace – solid phase microextraction (HS-SPME) followed by gas chromatography-mass spectrometry (GC-MS) has been developed for the determination of free volatile fatty acids in municipal wastewater samples. Polydimethylsiloxane-Carboxen (PDMS-CAR) fibre was found to have greater affinity to extract lower chain fatty acids. Extraction and gas chromatographic parameters of importance such as desorption time, sample volume, amount of salt to be added and extraction time have been optimized. Detection limits were in the low to medium mg/L levels. To evaluate the applicability of the developed HS-SPME procedure on real samples, municipal wastewater treatment plant samples were analysed.