NIST standard-reference solutions

Finally, the National Institute of Standards and Technology (NIST) in the United States has several chemical kinetics databases that are available for purchase from the Office of Standard Reference Data at NIST. The NIST Standard Reference Data Base 17 gives gas-phase rate constants through 1993 and Data Base 40 gives solution-phase data through 1992. In addition, aqueous-phase data are available through the Radiation Chemistry Data Center of the Notre Dame Radiation Laboratory (http //www.rcdc.nd.edu/). 

NIST Standard Reference Data Base 40 NDRL/NIST Solution Kinetic Database, Version 2.0. Data compiled and evaluated by A. B. Ross, B. H. J. Bielski, G. V. Buxton, D. E. Cabeli, C. L. Greenstock, W. P. Helman, R. E. Huie, J. Grodkawski, and P. Neta. Database developed by W. G. Mallard, A. B. Moss, and W. P. Helman (1994). 

Standardization Prepare a Standard Solution containing a total of about 10% solids, using sugars of known purity (e.g., USP Fructose Reference Standard USP Dextrose Reference Standard, or NIST Standard Reference Material maltose, Aid-rich Chemical Company or equivalent) that approximates, on the dry basis, the composition of the sample to be analyzed. Dissolve each standard sugar, accurately weighed, in 20 mL of purified water contained in a 50-mL beaker. Heat on a steam bath until all sugars are dissolved, then cool, and transfer to a 100-mL volumetric flask. Dilute to volume with water and mix. Freeze the solution if it is to be reused. 

Lead Nitrate Stock Solution Dissolve 159.8 mg of ACS reagent-grade Lead Nitrate (alternatively, use NIST Standard Reference Material containing 10 mg of lead per kilogram, or equivalent) in 100 mL of water containing 1 mL of nitric acid. Dilute to 1000.0 mL with water, and mix. Prepare and store this solution in glass containers that are free from lead salts. Each milliliter of this solution contains the equivalent of 100 pig of lead (Pb) ion. 

Most of the thermodynamic studies have been performed in aqueous solutions as the cycles and their derivatives are first of all ligands for complexation of water-soluble metal ions. Numerous compounds have been studied and, therefore, only a general overview of trends is given. More information can be find in commercial databases such as NIST Standard Reference Database 46 (Critically Selected Stability Constants of Metal Complexes) or The IUPAC Stability Constants Database (SC-Database) or in reviews <2005PAC1445> (critically evaluated data for DOTA 3 and TETA 4), <1999CCR97> (protonation constants of polyamines) and <2000CCR309> (protonation constants of polyamino-polycarboxylic acids). Overall basicity of the ligands is mostly the main determinant for values of stability constants of metal complexes. 

Ross, A. B. Mallard, W. G. Helman, W. P. Buxton, G. V. Huie, R. E. Neta, P. NDRL-NIST Solution Kinetics Database, Ver. 2 NIST Standard Reference Data National Institute of Standards and Technology Gaithersburg, MD, 1994. 

Values of NIST Standard-Reference pH Solutions from O C to 60°C ... 

Critical reviews and refinement of standard tabulations are of course indispensable to progress in thermochemistry. The pioneering work in the sulfur radical field was carried out by Benson [4]. More recently Wagman et al. [5] have reassessed the earlier NBS data for selected inorganic and C and C2 organic substances, both in the gas phase and in aqueous solution. Also, gas phase data up to 1988 were critically examined and tabulated in an extensive compilation [6]. Other critical reviews of value are by Griller et al. [7], Chase et al. [8], and Herron [9]. In addition to these articles, data for radicals in the gas phase are now the available in the NIST Standard Reference Data Base [10]. This chapter will make frequent use of the above compendia. At the same time, more recent results will be introduced and used where they are relevant and useful. 

Accuracy of in vivo and in vitro measurements of americium is determined through the use of standard, certified radioactive sources with known concentrations of americium. The primary source of certified americium standards is the National Institute of Standards and Technology (NIST). Standard solutions are available for241 Am (SRM 4322, 40 Bq/g [1.1 nCi/g]) and 243Am (SRM 4332, 40 Bq/g [1.1 nCi/g]). Standard Reference Materials for human lung (SRM 4351) and human liver (SRM 4352) are also available from NIST. 

A sample for which the true response is already known or is established is called a standard. A standard can be a primary standard, which is a standard through which other substances or solutions are made to be standards. It can also be a secondary standard, a solution whose concentration is known accurately either because it was prepared using a primary standard or because it was compared to another standard. All standards must ultimately be traced to a standard reference material (SRM). Standard reference materials are available from the National Institute of Standards and Technology (NIST) and should not be used for any other purpose in the laboratory (Section 5.4). Standardization is an experiment in which a solution is compared to a standard in order for itself to be a standard. The solutions used to establish a standard curve are often called reference standards and these must also be traceable to an SRM. 

Atomic Absorption Spectrophotometers This is a particular kind of spectrophotometer (see, for example, Figure 5.8) that utilizes a flame for the cuvette (requiring some maintenance for stability) and analyzes samples mostly for metals. The reference standards are thus solutions of metals. Such solutions are readily available and certified as being checked against NIST standards. 

In the above discussion, standard reference materials (SRMs) were mentioned often. A reference material (RM) is a material or substance suitable for use in calibrating equipment or standardizing solutions. A certified reference material (CRM) that a vendor indicates, via a certificate, is an RM. A standard reference material (SRM) is one that is distributed and certified by a certifying body, such as NIST. The SRM is the material to which all calibration and standardization materials should be traceable. A standard material becomes one when it is compared to or prepared from another. Ultimately, it all rests on the SRM — meaning all standard materials are traceable to an SRM (see Figure 5.10). 

Standard reference material (SRM) for wavelength accuracy, stray light, resolution check, and photometric accuracy can be purchased from NIST. Certified reference materials (CRMs) which are traceable to NIST and recertification services can be purchased from instrument manufacturers and commercial vendors [12]. The cost of neutral-density filters and prefabricated standard solutions in sealed cuvettes can be substantial. When purchasing performance verification standards from a secondary supplier other than a national standard organizations such as NIST in the United States and National Physical Laboratory (NPL) in the United Kingdom, make sure that the traceability of the standards are available in the certificates. The traceability establishes the relationship of individual results to the national standard through an unbroken chain of comparisons. 

At least one of the standards (the one used for initial calibration or the ICV standard) must be certified traceable to a national standard, such as the NIST-traceable standard reference materials. Certified stock standard solutions for the majority of environmental pollutants are available commercially. However, whether a stock standard is a certified solution or has been prepared by the laboratory, dilution errors during the standard preparation and analyte degradation in storage happen. The laboratories are able to detect such errors only by preparing and analyzing an independent, second source confirmation standard. 

Cells are typically exposed to ambient PM (PMio, PM2.5, UF), diesel exhaust particles (DEP), or cigarette smoke using these exposure systems (MazzareUa et al. 2007 Fukano et al. 2006 Hetland et al. 2004 Li et al. 2002). Some smdies have used well-characterized standard reference materials (SRMs) from the National Institutes of Standards and Technology (NIST 2009) and engineered nanoparticles, such as zinc oxide, titanium dioxide, in liquid medium (Li et al. 2003 Oberdorster 2001 Boland et al. 1999). Although standard or engineered materials are not true ambient PM, the materials are representative of ambient PM. These materials also elicit similar responses in cells to the ambient PM. The majority of the in vitro studies use doses in the range of 10-1000 pg/mL (PM mass/volume of the suspension solutions) with exposure durations of 2-72 h (Mitschik et al. 2008). 

Note Values were taken from A. B. Ross, NDRL/NIST Solution Kinetics Database, v. 2.0, Standard Reference Data, NIST, Gaithersburg, MD 20899, USA (http //allen.rad.nd.edu), also found in Ref. 32. DMPO stands for 5,5-dimethyl-l-pyrroline N-oxide. 

There are many papers dealing with a solution of this problem. For many years a NIST (National Institute for Standards and Technology) conical transducer developed by Proctor [1982, 1986] out of a Standard Reference Material (SRM) and mass-backed (600 gr.) was used as a reference for AE measurements. Several new approaches have explored other transducer materials out of polyvinylidene fluoride (PVDF) or copolymers (Hamstad 1994 Hamstad and Fortunko 1005 Bar-Cohen et al. 1996 Hamstad 1997) as well as embedded sensors (Glaser et al. 1998). 

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