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Air Quality and Emissions Assessment
Published in Wayne T. Davis, Joshua S. Fu, Thad Godish, Air Quality, 2021
Wayne T. Davis, Joshua S. Fu, Thad Godish
In some manual sampling methods, instrument calibration is limited to measuring airflow rates. Such calibration may be conducted using flow-measuring instruments based on primary or secondary standards. A primary standard is one that is directly traceable to the National Institute of Standards and Technology (NIST). A primary standard would be, e.g. a bubble meter (gas burette and soap solution used for low flows) or volumetric flask. In the latter case, the volumetric flask may be used to calibrate wet or dry test meters that may be used to calibrate rotometers. Wet and dry test meters and rotometers are secondary standards. Because of their portability and ease of use, field instruments are commonly calibrated with secondary standard devices (such as rotometers). Based on U.S. Environmental Protection Agency (U.S. EPA) regulations, airflow rate measurements must be made using instruments traceable to an authoritative volume (e.g. NIST).
Endotoxin Testing
Published in Sandeep Nema, John D. Ludwig, Parenteral Medications, 2019
The term secondary standard is used here to denote one that has been standardized with reference to a primary standard. The term “Control Standard Endotoxin” (CSE) is commonly used for such secondary endotoxin standards. A CSE may be defined as “an endotoxin preparation other than the RSE that has been standardized against the RSE.” This definition was taken from the USP XXI BET chapter, which was published prior to harmonization of the chapter with the JP and Ph. Eur. Although that version of the BET chapter is now obsolete, the definition is still applicable. The most widely used CSEs are those supplied by LAL reagent manufacturers. These are usually preparations of LPS from E. coli, such as E. coli O113:H10 or E. coli O55:B5, without or with additives or fillers.
Laboratory Apparatus: Chemicals and Instruments
Published in Barbara A. Hauser, Practical Manual of Wastewater Chemistry, 2018
Standards are in use for titration. A titrant must have an exact concentration. It is the reagent which measures the component being tested for. A Primary Standard is a chemical solution which, as prepared, can be relied upon to be pure and to be the exact concentration it is made up at. A Secondary Standard is a solution which is prepared from an impure chemical, and its exact concentratior was not known. It is reacted with a primary standard (standardized) on a mole to mole basis, to determine its exact concentration. Most often it is the secondary standard that is the needed compound as a titrant for the test procedure; the purpose for the primary standard is to standardize the secondary.
Reliability of chloride testing results in cementitious systems containing admixed chlorides
Published in Sustainable and Resilient Infrastructure, 2023
Ahmed A. Ahmed, Naga Pavan Vaddey
To assess the reliability of chloride testing results, 36 different cement pastes – ‘3 cementitious material types’ × ‘4 admixed chloride levels (Cladmixed)’ × ‘3 water-to-cementitious material ratio (w/c) values,’ were investigated. The three cementitious material types included OPC, CAC, and CSA. Four levels of Cladmixed by mass of cement (0%, 0.05%, 0.25%, and 1%) and three levels of w/c (0.35, 0.45, and 0.55) were evaluated as other testing parameters. The oxide compositions of the cements were determined using X-ray fluorescence analysis (XRF) and are reported in Table 1. Primary standard reagents, NaCl (>99.9% purity) and AgNO3 (≥99.80% purity), were used to prepare chemical solutions needed for the study, i.e., for preparing mix water for pastes and for preparing standard solutions needed for chloride titration. A Type II reagent water that met ASTM D1193 requirements was used to prepare all solutions.
Accurate nanoparticle size determination using electrical mobility measurements in the step and scan modes
Published in Aerosol Science and Technology, 2022
Kaleb Duelge, George Mulholland, Michael Zachariah, Vincent A. Hackley
DMA is an aerosol sizing technique that has been used extensively for particle measurements related to combustion (Lamberg et al. 2018; Choi, Myung, and Park 2014), climate (Gibson, Hudson, and Grassian 2006; Smith et al. 2010), and particle engineering (Tsai et al. 2011; Guha et al. 2012). DMA has also been employed in the measurement of particle size standards. It has been used to certify NIST standard reference material (SRM) 1963 (Mulholland, Bryner, and Croarkin 1999), 1963a, and 1964 (Mulholland et al. 2006). DMA was also one of many techniques used to assign reference values to NIST RMs 8011, 8012, and 8013, as previously mentioned. DMA is not generally used as a primary calibration technique because of the uncertainty in the flow dynamics where the aerosol inlet flow meets the sheath flow. In addition, there may be minor fringe effects on the electric field used for separation. DMA is more commonly used as a secondary calibration technique, where the known size of a primary standard is used for calibration and an unknown particle is measured and is traceable to the primary standard. DMA is suited for these measurements because it is highly reproducible, yields a number-weighted distribution, can measure high particle number counts with correspondingly higher statistical significance, the size resolution is easily controllable, and it has a well-defined electrical mobility transfer function (the probability that particles of given electrical mobility will exit the DMA column).
Emplacement and Paleozoic and Cretaceous recrystallisation of the Broughton Arm Peridotite in Western Fiordland, New Zealand
Published in New Zealand Journal of Geology and Geophysics, 2019
T. Dwight, J. M. Scott, J. J. Schwartz
Zircon grains were separated at California State University Northridge by pulverising the samples with a jaw crusher and disk mill and then undertaking density separation using a Wilfley table and heavy liquids. Grains were mounted in epoxy and polished and then imaged on a Gatan MiniCL detector attached to a FEI Quanta 600 scanning electron microscope. Analyses were conducted at the University of California Santa Barbara using a Nu Plasma multi-collector inductively coupled plasma mass spectrometer (MC-ICPMS) with a Photon Machines 193 ArF excimer laser with HelEx cell. The spot size for all analyses was ∼35 microns and the repetition rate was 4 Hz. Primary standard 91500 was analysed every 10 analyses. Uranium-Pb ratios were collected in one analytical session in November 2017 following methods described in Kylander-Clark et al. (2013). U–Pb isotope ratios and their uncertainties were calculated using Iolite 3.0 (Paton et al. 2010). A typical ablation of 12–26 ng of material yields 2σ standard errors of 1–1.5% for 206Pb/238U and 0.3–1% on 207Pb/206Pb using down-hole elemental-fractionation correction (Paton et al. 2011). Temora-2 and GJ-1 standards were also analysed throughout the analytical session and yielded concordant results with 206Pb/238U ages of 417.1 ± 4.8 (n = 7; mswd = 1.2) and 601.3 ± 3.8 (n = 9; mswd = 0.5), respectively. The quoted dates in the text and tables are reported at 95% confidence interval and are assigned 2% total uncertainties, except when comparing analyses within the same sample or grain.