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In Vivo Assessment of Dermal Absorption
Published in David W. Hobson, Dermal and Ocular Toxicology, 2020
George J. Klain, William G. Reifenrath
Tenax® samples are placed directly into scintillation vials and the columns are flushed with 10 ml of ACS. Radioactivity in the solutions is determined using a liquid scintillation spectrometer equipped with an automatic external standard.
Measurement of Exposure and Dose
Published in Samuel C. Morris, Cancer Risk Assessment, 2020
Several pollutants of interest could not be included in the study because they were not amenable to collection on Tenax. Highly volatile chemicals such as vinyl chloride and methylene chloride would “break through” the Tenax cartridge before the sampling period was over. Any sorbent can hold only a given amount of a particular chemical; when that limit is exceeded, the chemical “breaks through” and some of the sample is lost. To assure no break through occurred or to enable the amount of material that breaks through to be estimated, a second cartridge is often put in the sampling train following the first. Formaldehyde is reactive and cannot be collected on Tenax, nor can any other substances such as phenols.
Inhalation Toxicology of Chemical Agents
Published in Brian J. Lukey, James A. Romano, Salem Harry, Chemical Warfare Agents, 2019
Stanley W. Hulet, Paul A. Dabisch, Robert L. Kristovich, Douglas R. Sommerville, Robert J. Mioduszewski
For systems that generate nerve agent vapor, the stability of the generated atmosphere can be continuously monitored by using hydrogen flame emission detection, a selective monitor for phosphorus-containing species. Additionally, a quantitative measurement of the agent concentration in the chamber can be determined using solid-phase sorbent tubes. Small samples of the nerve agent vapor–containing environment are pulled through glass tubes containing a sorbent material, such as TENAX TA. Once the sample is collected, the amount of agent is quantified using gas chromatography. If the amount of air drawn through the sorbent tube is known, the concentration of nerve agent (mg/m3) can be calculated (Muse et al., 2006).
Protozoans in subgingival biofilm: clinical and bacterial associated factors and impact of scaling and root planing treatment
Published in Journal of Oral Microbiology, 2020
Marie Dubar, Marie-Laure Zaffino, Thomas Remen, Nathalie Thilly, Lisiane Cunat, Marie-Claire Machouart, Catherine Bisson
About the pathological sites in patients with periodontitis, only T. tenax displays a significant decrease in presence after SRP, with absolute and relative reduction of 11% and 50% respectively (p = 0.001). Moreover, T. tenax was found in a lower quantity after SRP (increase in the cycle threshold of PCR- Supplementary Table 1). After periodontal treatment, some healthy sites from the periodontitis group experienced ST1 elimination, others an occurrence or no modification of this amoeba presence. In addition, among the two T. tenax-positive healthy sites before therapy, one site remained positive and the other presented a flagellate elimination after treatment. Moreover, one healthy site negative before SRP become positive after. These variations of protozoan presence observed in healthy sites from periodontitis patients were not statistically significant (Table 2). The co-identification of both ST1 and ST2 was statistically rare and concerned one same sample alone (p < 0.0001).
Detection and analysis of endogenous polar volatile organic compounds (PVOCs) in urine for human exposome research
Published in Biomarkers, 2019
Cassandra R. O’Lenick, Joachim D. Pleil, Matthew A. Stiegel, Jon R. Sobus, M. Ariel Geer Wallace
All urine samples, PBS blanks, and calibration standards were prepared and analyzed identically. To evaluate PVOCs as urinary biomarkers, we explore a passive diffusion transfer method to capture polar volatile organic carbons excreted in human urine. The core study design was presented previously (Pleil et al. 2008, Hubbard et al. 2009) and adapted here to be relevant and appropriate for human urine. The passive diffusion transfer method is as follows: Tenax tubes are cleaned and conditioned with ultra-high purity helium at 290 °C for 2 h and 20 min prior to exposure.Each 75 mL glass bulb is washed and then heated to 70 °C to remove residual compounds.Once cooled to room temperature, glass bulbs are rinsed with DCM, allowed to dry, rinsed again with high-purity deionized water, and allowed to dry thoroughly before samples are added.Once bulbs are thoroughly dry, they are placed on an inclined rack, and a clean Tenax absorbent tube is inserted into each bulb.Urine samples and calibration standards are stored at −20 °C and thawed to room temperature before testing.Urine samples (1.5 mL) are transferred to individual bulbs via glass syringe.Blanks are prepared by injecting, via glass syringe, 1.5 mL of PBS into individual bulbs. Blanks are tested in duplicate.Calibration standards are prepared by injecting, via syringe, 130 μL of the standard mixture (765 μg/mL) into glass bulbs containing 1.5 mL of PBS. Calibration standards were tested in duplicate.Bulbs are angled approximately 15° with respect to the horizontal, and care was taken to keep the aqueous solution from contacting the Tenax tube directly.Bulbs are sealed and left at room temperature for 24 h.Tenax tubes are removed, capped and stored for subsequent analysis.