Method reference

Here we want to document that FAMUSAMM actually provides an enhanced computational efficiency both as compared to SAMM as well as to the reference method which is characterized by exact evaluation of the Coulomb sum. To that aim we have carried out a series of test simulations for systems of... 

Reference methods for criteria (19) and hazardous (20) poUutants estabHshed by the US EPA include sulfur dioxide [7446-09-5] by the West-Gaeke method carbon monoxide [630-08-0] by nondispersive infrared analysis ozone [10028-15-6] and nitrogen dioxide [10102-44-0] by chemiluminescence (qv) and hydrocarbons by gas chromatography coupled with flame-ionization detection. Gas chromatography coupled with a suitable detector can also be used to measure ambient concentrations of vinyl chloride monomer [75-01-4], halogenated hydrocarbons and aromatics, and polyacrylonitrile [25014-41-9] (21-22) (see Chromatography Trace and residue analysis). 

Sampling of Particulates. Ambient air suspended particulate concentration was traditionaUy measured gravimetricaUy over a 24-h period with a "Hi-Vol" sampler. However, in 1987 the EPA changed ambient particulate control to the PM q reference method (24). In the PM q method, a... 

Method vahdation is the demonstration, accompanied by a high degree of assurance, that the test method consistently performs as expected. Vahdation of test methods is especially important when the intended method differs from a compendial or other referenced method and yet is expected to provide equivalent or perhaps better test results. When the reference method is to be used unchanged, no vahdation is necessary. Thus a primary benefit of using compendial methods as written is not needing to do a method vahdation. 

U. S. EPA Regulations on Standards ofPeformanceforNeir Stationay Sources, 40 CER 60, Appendix A, Reference Methods, Washington, D.C., 1993. ASTM D3685-92, Standard Test Methodfor Sampling and Determination of Particulate Matter in Stack Gases, American Society for Testing Materials, Philadelphia, Pa., 1992. 

Inductively coupled argon plasma (icp) and direct current argon plasma (dcp) atomic emission spectrometry are solution techniques that have been appHed to copper-beryUium, nickel—beryUium, and aluminum—beryUium aUoys, beryUium compounds, and process solutions. The internal reference method, essential in spark source emission spectrometry, is also useful in minimizing drift in plasma emission spectrometry (17). Electrothermal (graphite... 

Ghlorophenol Analysis. The chlorophenols can be analy2ed by acidimetric titration of the hydroxyl function (50). This overall method yields only an approximate evaluation for mixtures. To analy2e chlorophenol mixtures, gas chromatography has been the reference method used, as it made it possible to separate and quantify the various chlorophenols (51), but this technique can be a source of errors the gem-chlotinated cyclohexadienones that may be present along with the chlorophenols are broken back down iato lighter chlorophenols under the analysis conditions usually employed. 

Each samphng method requires the use of complex samphng equipment that must be calibrated and operated in accordance with specified reference methods. AdditionaUy, the process or source that is being tested must be operated in a specific manner, usually at rated capacity, under normal procedures. 

Velocity and Volumetric Flow Rate The U.S. EPA has published Method 2 as a reference method for determining stack-gas velocity and volumetric flow rate. At several designated sampling points, which represent equal portions of the stack volume (areas in the stack), the velocity and temperature are measured with instrumentation shown in Fig. 25-27. 

Moisture Content EPA Method 4 is the reference method for determining the moisture content of the stack gas. A value for moisture content is needed in some of the calculations for determining pollution-emission rates. 

Sulfur Dioxide EPA Method 6 is the reference method for determining emissions of sulfur dioxide (SO9) from stationary sources. As the gas goes through the sampling apparatus (see Fig. 25-33), the sulfuric acid mist and sulfur trioxide are removed, the SO9 is removed by a chemical reaction with a hydrogen peroxide solution, and, finally, the sample gas volume is measured. Upon completion of the rim, the sulfuric acid mist and sulfur trioxide are discarded, and the collected material containing the SO9 is recovered for analysis at the laboratory. The concentration of SO9 in the sample is determined by a titration method. 

Nitrogen Oxides (NO ) EPA Method 7 is the reference method for determining emissions of nitrogen oxides from stationaiy sources. Samphng for NO by this method is relatively simple with the proper equipment. 

Fluorides Two EPA reference methods, Method 13A and Method 13B, can be used to determine total fluoride emissions from a stationary source. The difference in the two methods is the analyti-... 

Hydrogen Chloride (HCl) EPA Method 26 is the reference method used to measure hydrogen chloride emissions from stationaiy sources. The method is applicable for determining emissions of hydrogen halides (HX) such as hydrogen chloride (HCl), hydrogen... 

The primary reference method used for measuring carbon monoxide in the United States is based on nondispersive infrared (NDIR) photometry (1, 2). The principle involved is the preferential absorption of infrared radiation by carbon monoxide. Figure 14-1 is a schematic representation of an NDIR analyzer. The analyzer has a hot filament source of infrared radiation, a chopper, a sample cell, reference cell, and a detector. The reference cell is filled with a non-infrared-absorbing gas, and the sample cell is continuously flushed with ambient air containing an unknown amount of CO. The detector cell is divided into two compartments by a flexible membrane, with each compartment filled with CO. Movement of the membrane causes a change in electrical capacitance in a control circuit whose signal is processed and fed to a recorder. 

The West-Gaeke manual method is the basis for the U.S. Environmental Protection Agency reference method for measurement of SO2 (6). The method uses the colorimetric principle i.e., the amount of SO2 collected is proportional to the amount of light absorbed by a solution. The collection medium is an aqueous solution of sodium or potassium tetrachloromercu-... 

Describe the rationale for the U.S. Environmental Protection Agency s establishment of a standard reference method for measurement of National Ambient Air Quality Standard air pollutants. 

Under what conditions can another method be substituted for a standard reference method ... 

Using the Code of Federal Regulations, list the current reference methods for measuring NO2, O3, SO2, CO, total suspended particulate matter, and lead. 

Review the air pollution literature and describe the difficulties in establishing a standard reference method for measuring NO2. 

Releases to Air. In April 1989, you conducted stack tests to determine air releases from the battery facility. The release data provided baseline data for a proposed 1990 air emission reduction program. The tests were performed using EPA Reference Method 12, which determines exhaust concentrations as total elemental lead, and EPA Reference Methods 1-4, which determine total exhaust volumes. Releases from all stacks and vents at the facility were measured, including those from the following release points ... 

One example is Finland, where in 1999 the EPS system was chosen as the reference method in the area of building services, including industrial air tech nology. 

Reference method A method of analysis to which other methods of analysis are compared. 

An ASTM recommended practice (A Standard Reference Method for Making Potentiostatic and Potentiodynamic Anodic Polarisation Measurements, G5 1972) has been issued. It provides a means of checking experimental technique and instrumentation using a specimen from a single heat of AISI Type 430 stainless steel, which is available from ASTM. ... 

Direct or indirect methods may be used to determine moisture in dehydrated foods. Indirect methods must be calibrated in terms of direct methods—the most common of which are the oven, distillation, and Fischer methods. Accuracy of the direct methods is difficult to evaluate except by comparison with a chosen reference method. Several reference methods are reviewed, but none can be given an unqualified recommendation as most practical and suitable for all foods. An indirect measure of moisture is the equilibrium vapor pressure of water, which can be measured easily and accurately. Arguments are presented to show that vapor pressure may be a better index of the stability of dehydrated foods than the moisture content, which has been frequently used for this purpose. 

In a search for an accurate method of measuring moisture in foods, one cannot overlook the essential requirements of convenience, speed, and precision. Many currently used methods meet these requirements without necessarily yielding accurate results under the conditions used. Probably most important are the electrical methods (IS, 24, 26, 36), the air- and vacuum-oven methods (/, 2, 6, 18, 25, 28, 36), distillation with organic solvents (1, 3, 7, 12, 13, 26, 35), and the Karl Fischer reagent method (9, 11, 26, 31, 32). Without discussing the relative merits of these methods, it can be assumed that accurate results could be obtained with each method by calibration against some accurate reference method. 

It appears then that the establishment of practicable and accurate reference methods presents one of the major problems in the determination of moisture in foods. The present paper summarizes some of the important factors that govern the accuracy of moisture determinations in general, and reviews some of the recently published attempts to develop methods that might serve as useful reference standards for dehydrated foods, and especially for dehydrated vegetables and fruits. 

In choosing a reference method for the calibration of others, one is therefore restricted to direct methods. For this reason consideration is given here to some of the assumptions that underlie the important methods of this class. 

Redrying Procedure Reference Method ft Loss in weight, % HaO... 

The problem was, then, to determine the correct time of drying at a specified temperature by calibration against some reference method. As indicated above, it was also necessary to establish reproducible methods of sampling and grinding of the vegetable, and of maintaining in the oven a uniform temperature and a low pressure of water vapor, and to consider other experimental factors (18). 

The ground material (40-mesh) is dried in vacuo at room temperature over a desiccant (magnesium perchlorate) that permits practically no water vapor pressure. An assumption was made that at room temperature and in the absence of air, decomposition and oxidation would be negligible. It was found, however, that a direct application of this reference method was not practicable from a routine standpoint, because the time to reach equilibrium was exceedingly long (6 to 9 months). 

A secondary reference method known as the redrying procedure was therefore established for a more rapid calibration. 

Comparison of the results obtained by the redrying procedure with those by the primary reference method (room temperature, in vacuo over magnesium perchlorate) is shown in Table II. The agreement of the two sets of results was within 0.2% or better, which is considered satisfactory and serves to confirm the suitability of the redrying procedure as a secondary reference standard. 

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