Diffusion vapour transfer modelling for an end-capped atomizer. Part 1. Atomizer with closed injection port |
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| Institution: | 1. Key Laboratory of Cluster Science, Ministry of Education of China, Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing 100081, P. R. China;2. Key Laboratory of Organic Optoelectronics & Molecular Engineering, Ministry of Education, Department of Chemistry, Tsinghua University, Beijing 100084, China;1. Ramsay Générale de Santé, Hôpital Privé Jean Mermoz, Centre Orthopédique Santy, Lyon, France;2. Orthopaedic Specialty Hospital, Mercy Medical Center, Baltimore, MD, USA;3. Departments of Orthopaedic Surgery & Shoulder/Elbow Surgery, The Rothman Institute-Thomas Jefferson, Philadelphia, PA, USA;1. Medical School of Ningbo University, Ningbo 315211, China;2. Laboratory of Metabolism, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892, USA;3. Hunan Normal University, Changsha 410081, China;4. Ningbo College of Health Sciences, Ningbo 315100, China;1. Department of Biomedical, Chemical & Environmental Engineering, College of Engineering and Applied Science, University of Cincinnati, Cincinnati, OH 45221-0071, United States;2. Department of Civil and Architectural Engineering & Construction Management, College of Engineering and Applied Science, University of Cincinnati (ML-0071), P.O. Box 210071, Cincinnati, OH 45221-0071, United States;1. Department of Statistics, School of Statistics and Mathematics, Yunnan University of Finance and Economics, Kunming, Yunnan, 650221, China;2. Shanghai Lixin University of Accounting and Finance, Shanghai, 201209, China |
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| Abstract: | For end-cap equipped transverse-heated graphite atomizers (THGA) with integrated contacts used for analytical atomic spectrometry, a model equation describing the diffusional losses of analyte atomic vapour through the tube ends was constructed. The model assumes that the atomic density distribution is stepwise linear along the tube axis and the absence of a sample injection hole. With a quartz tube system, providing controlled experimental conditions at room temperature, the time constant of the diffusion removal function (TR) of mercury vapour was determined for various open and end-capped tube geometries. These results were also described by an empirical multiple regression equation with a residual standard deviation of 5%. The theoretically predicted TR values, corrected with an empirical factor of 1.33, agreed well (correlation coefficient = 0.996) with the experimentally obtained TR values for the endcapped quartz tubes. For the Perkin-Elmer THGA tubes, the diffusional transfer model was evaluated using the integrated atomic absorbance ratio between various end-capped and open tubes. This is meaningful because the signal ratio for graphite atomizers is closely equal to the corresponding TR ratio. For recommended atomization temperatures the average deviation between these experimental signal ratios and the theoretically predicted ratios for the elements Ag, In, Cd, Co, Hg and Cu was 1–5% for various end-capped tube geometries. The results for the individual elements deviated more from the theoretically predicted ratios mainly because of small differences in the mean gas-phase temperature between open and end-capped tubes. For elements which tend to form molecules in the gas phase at low temperatures and for which the atomization efficiency is increased with the atomization temperature, the experimental ratios tended to be higher than the theoretically predicted values (In, Al, Se, Sn, As), whereas experimental ratios were slightly lower for other elements (Cd, Co, Cu). |
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