Optimization of Solid Phase Microextraction for Determination of Disinfection By-products in Water
Notice bibliographique
Résumé
A new technique for sample preparation and trace analysis of organic pollutants in water using mixed-phase thin film (MPTF) devices, combined with direct thermal desorption, cold trapping, gas chromatography-mass spectrometry (GC-MS) is presented for the first time. Two novel analytical devices, Carboxen/polydimethylsiloxane (CAR/PDMS) and polydimethylsiloxane/divinylbenzene (PDMS/DVB) TF samplers were fabricated using spin coating technique and glass wool fabric mesh as substrate. The samplers were easily tailored in size and shape by cutting tools. Good durability and flat-shape stability were observed during extractions and stirring in water. The latter characteristic obviates the need for an extra framed holder for rapid thin film microextraction (TFME) and makes the samplers more robust and user-friendly. The analytical performance of the MPTF devices was satisfactorily illustrated and compared with those of solid phase microextraction (SPME) fibers and PDMS thin film membrane using water samples spiked with seven N–nitrosamines (NAs), known as disinfection by-products (DBPs) in drinking water. Marked enhancement of extraction efficiencies (typically more than one order of magnitude) for the N-nitrosamines, including the hydrophilic ones, was obtained with the MPTF devices under generally pre-equilibrium conditions, compared to the SPME fibers and PDMS thin film membrane. The analytical results obtained in this study, including linearity, repeatability and detection levels at low ng/L for the tested compounds, indicate that the new thin film devices are promising for rapid sampling and sample preparation of trace levels of polar organic pollutants in water with sensitivities higher than SPME fibers and with a wide application range typical of mixed-phase coatings. The user-friendly format and robustness of the novel devices are also advantageous for on-site applications, which is the ultimate use of thin film samplers. Moreover, the thin film fabrication approach developed in this study offers the possibility of making other novel samplers with PDMS or different absorptive polymers such as polyacrylate (PA) and polyethylene glycol (PEG) as particle-free, or as particle-loaded thin films with a variety of adsorptive solid particles. \nIn another development in the course of this research, the performance and accuracy of the SPME fiber approach for sample preparation of selected DBPs were demonstrated and compared with the conventional liquid-liquid extraction (LLE) method by real drinking water samples analysis in collaboration with Health Canada. Four regulated trihalomethanes (THMs) and seven other DBPs known as priority by-products, including four haloacetonitriles, two haloketones and chloropicrin, were analyzed in real samples during two separate comparative studies. In each study, duplicate samples from several water treatment and distribution systems in Canada, collected and stabilized under the same protocol, were analyzed in parallel by two independent labs; in the University of Waterloo by an optimized headspace SPME-GC-MS and in Health Canada by a LLE-GC-ECD (electron capture detection) method equivalent to EPA 551.1. The values for the concentration of the analytes in the samples obtained by the two methods were in good agreement with each other in majority of the cases indicating that SPME affords the promise of a dependable sample preparation technique for rapid DBPs analysis. In particular, it was shown that the SPME fiber approach combined with GC-MS is a fast reliable alternative to the LLE-GC-ECD (EPA 551.1) method for analysis of the regulated THMs in the concentration ranges that are typical and relevant for drinking water samples.
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,001 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,001 | 0,000 |
| Méta-épidémiologie (sens large) | 0,001 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,001 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».