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- Iadaresta, Francesco, et al.
(författare)
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Application of graphitic sorbent for online microextraction of drugs in human plasma samples
- 2015
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Ingår i: Journal of Chromatography A. - : Elsevier BV. - 0021-9673 .- 1873-3778. ; 1422, s. 34-42
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Tidskriftsartikel (refereegranskat)abstract
- In the present work a new sorbent based on graphitized carbon (CarbonX (R) COA) was evaluated in microextraction by packed sorbent (MEPS) for extraction of lidocaine and ropivacaine from human plasma samples. The new graphitic sorbent showed high recoveries of lidocaine and ropivacaine compared to C18 sorbent In the present study the G-MEPS (syringe packed with graphitic sorbent) was connect online with liquid chromatography tandem mass spectrometry (LC-MS/MS). In order to obtain a fast and reliable method different factors affecting MEPS performance were investigated. The extraction efficiency of the graphitic sorbent was compared with silica-based sorbents used in MEPS. The G-MEPS was also evaluated for reuse (50-100 times). The recoveries of lidocaine and ropivacaine from plasma samples were 79% and 82%; respectively. The method was validated according to FDA (Food and Drug Administration) guideline for bioanalytical method validation. Linearity was assessed in the range 5-2000 nmol/L, with coefficient of determination r(2) > 0,995 (n=3) for lidocaine and r(2) > 0.997 (n=3) for ropivacaine. The lower limit of quantification (LLOQ) was 5 nmol/L and the limit of detection (LOD) was 1 nmol/L for studied analytes in plasma samples. For both analytes considered in this study the accuracy values in plasma samples were ranged from 86% to 113%. The Inter-day precisions, expressed as relative standard deviation (%RSD), at three different concentrations (QC-samples) ranged from 8% to 9% for lidocaine, and from 4% to 11% for ropivacaine.
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| 2. |
- Luongo, Giovanna, et al.
(författare)
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Determination of aniline and quinoline compounds in textiles
- 2016
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Ingår i: Journal of Chromatography A. - : Elsevier BV. - 0021-9673 .- 1873-3778. ; 1471, s. 11-18
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Tidskriftsartikel (refereegranskat)abstract
- A simple method for simultaneous determination of twenty-one analytes, belonging to two classes of compounds, aromatic amines and quinolines, is presented. Several of the analytes considered in this study frequently occur in textiles goods on the open market and have been related to allergic contact dermatitis and/or are proven or suspected carcinogens. The method includes an efficient clean-up step using graphitized carbon black (GCB) that simplifies and improves the robustness of the subsequent GC-MS analysis. Briefly, after solvent extraction of the textile sample, the extract is passed through a GCB SPE cartridge that selectively retain dyes and other interfering compounds present in the matrix, producing a clean extract, suitable for GC-MS analysis, is obtained. The method was evaluated by spiking blank textiles with the selected analytes. Method quantification limits (MQL) ranged from 5 to 720 ng/g depending on the analyte. The linear range of the calibration curves ranged over two order magnitude with coefficients of determination (R-2) higher than 0.99. Recoveries ranged from 70 to 92% with RSDs 1.7-14%. The effectiveness of the method was tested on a variety of textile materials samples from different origin. In a pilot explorative survey, 2,6-dichloro-4-nitroaniline was detected in all the analysed clothing samples in concentrations ranging from 1.0 to 576 mu g/g 2,4-dinitroaniline was detected in four of the seven samples with a highest concentration of 305 mu g/g Quinoline was detected in all samples in concentrations ranging from 0.06 to 6.2 mu g/g. (C) 2016 Elsevier B.V. All rights reserved.
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| 3. |
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| 4. |
- Tollbäck, Johanna, et al.
(författare)
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Air sampling with Empore solid phase extraction membranes and online single-channel desorption/liquid chromatography/mass spectrometry analysis : Determination of volatile and semi-volatile organophosphate esters
- 2006
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Ingår i: Journal of Chromatography A. - : Elsevier BV. - 0021-9673 .- 1873-3778. ; 1129:1, s. 1-8
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Tidskriftsartikel (refereegranskat)abstract
- A method for determining organophosphate esters in air samples using C8 Empore solid phase extraction (SPE) membranes has been developed. After the sampling the analytes trapped in the membrane are completely desorbed with methanol, using an extraction cell connected online to the organic modifier channel of a HPLC gradient pump. The addition of water to the mobile phase prior to analytical chromatography ensures that the analytes are refocused and efficiently separated. Sampling with Empore SPE membranes enables the collection of analytes in both the vapour phase and particulate matter. During the air sampling procedure no losses were observed after 24 h of sampling, yielding a total volume of 14.4 m3, even for the most volatile compound used in this investigation (trimethylphosphate). Complete desorption was observed for all the organophosphate esters and recoveries were greater than 95%, with a relative standard deviation of less than 8%. The limits of detection ranged between 0.4 and 19 pg/m3. The effect of particulate matter on the extraction efficiency was investigated in detail by spiking the membranes with reference standard material. It was also found that the SPE membranes could be stored for at least 5 days at room temperature without any evidence of loss. The efficacy of the method was verified using real samples from different common indoor environments. Interestingly, significant quantities of several phosphate esters were found in a NIST standard reference material (urban dust, SRM 1649a).
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| 5. |
- Tollbäck, Johanna, et al.
(författare)
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Determination of the flame retardant tetrabromobisphenol A in air samples by liquid chromatography-mass spectrometry.
- 2006
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Ingår i: Journal of Chromatography A. - : Elsevier BV. - 0021-9673 .- 1873-3778. ; 1104:1-2, s. 106-12
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Tidskriftsartikel (refereegranskat)abstract
- An original method based on LC-MS for determination of the flame retardant tetrabromobisphenol A (TBBPA) in air is presented, as an alternative to the traditionally used GC-MS. The soft ionization in LC-MS makes it possible to monitor the intact molecule and to use 13C-labelled TBBPA as an internal surrogate standard, two features that improve both accuracy and precision of the analyses. Comparison of different acquisition modes in electrospray ionization showed that the lowest detections limit, 3.1 pg TBBPA injected, was obtained in SIM monitoring the molecular ions 542.7/544.7. A fragmentation pathway of TBBPA in LC-ESI-MS is suggested. The only sample clean-up steps required are solvent reduction and filtration of the sample extract. Recoveries were 93% at a 30 ng level and 75% at 3 ng. The new method was tested by analyses of air samples collected at a recycling plant for electronic equipment. The amount of TBBPA found was 13.8 ng/m3 with an RSD of 5.9%. Furthermore, it was found that TBBPA in a standard solution could be partially debrominated, if not carefully protected from light during storage.
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