Prescribed methods

The ISO method prescribes polystyrene standards with tetrahydrofuran as the eluent, but this equation can also be used with other narrow distribution standards, provided the same elution solvent and the same standards are used for a comparison. Further, the ISO method requires the result to be greater than 6 for one decade of the molar mass. Because calibration curves are usually not linear, this decade should lie nearly symmetrically around the peak maxima of the samples in question. The required value of 6 is easy to fulfill, as results of 10 or more are usual with modern columns. If so-named linear or mixed... 

Epoxidation using a chiral fructose-derived ketone is easy to carry out, as it occurs in aqueous conditions. The reactions were performed without any modification of the published procedure. The glassware has to be free of trace metal, which can decompose the oxone the use of a plastic spatula is recommended and the volumes must be measured using glass-graduated cylinders. Table 6.2 gives different examples of epoxides which can be obtained using the method prescribed. 

A plethora of pure drugs, their respective combinations and their dosage forms have been assayed by NMR-spectroscopy quantitatively by various researchers and the result(s) thus obtained were duly verified and compared with the standard methods prescribed in various official compendia. A few typical examples of such drugs shall be described briefly here ... 

The purpose of this chapter is to describe well-established analytical methods that are available for detecting and/or measuring and/or monitoring total petroleum hydrocarbons and their metabolites, as well as other biomarkers of the exposure and effect of total petroleum hydrocarbons. The intent is not to provide an exhaustive list of analytical methods. Rather, the intention is to identify well-established methods that are used as the standard methods approved by federal agencies and organizations such as the Environmental Protection Agency and the National Institute for Occupational Safety and Health (NIOSH) or methods prescribed by state governments for water and soil analysis. Other methods... 

The experiments were carried out on high purity aluminium from different producers (Table I) and Al-Ga alloys. The impurity concentration in the used materials was determined by glow discharge mass-spectrometry. The total impurity content in pure aluminium (0.4 - 7.7 ppm) was defined as the sum of the concentration of all found elements.The residual resistivity ratio RRR=p(273K)/p(4.2K) of the materials was measuredby the method prescribed by the U.S. National Bureau of Standards. 

The discipline of analytical chemistry is wide and catholic. It is often difficult for a food chemist to understand the purist concerns of a process control chemist in a pharmaceutical company. The former deals with a complex and variable matrix with many standard analytical methods prescribed by Codex Alimentarius, for which comparability is achieved by strict adherence to the method, and the concept of a true result is of passing interest. Pharmaceuticals, in contrast, have a well-defined matrix, the excipients, and a well-defined analyte (the active) at a concentration that is, in theory, already known. A 100-mg tablet of aspirin, for example, is likely to contain close to 100 mg aspirin, and the analytical methods can be set up on that premise. Some analytical methods are more stable than others, and thus the need to check calibrations is less pressing. Recovery is an issue for many analyses of environmental samples, as is speciation. Any analysis that must... 

As-synthesised HMS was prepared using the method prescribed by Tanev and Pinnavaia [1,3]. 0.27 mol of dodecylamine was dissolved in 9.09 mol of ethanol and 29.6 mol of water. 1 mol of TEOS was then added to the mixture under vigorous stirring. The reaction mixture was allowed to age under room temperature for 18 hours. After ageing, the solid reaction product was washed with deionised water and recovered from the aqueous mixture by filtration. The moist solid was subsequently air-dried and sieved into the desired particle sizes using mesh no. 40 (0.425mm) and 60 (0.250mm). Some amount of the as-synthesised HMS sample was then sent for calcination at 630°C for 4 hours. 

Method of analysis of commercial product suitable for use in mine expls, as practiced at US Bureau of Mines, Bruceton and Pittsburgh, Pa, is described in Ref 1. The method is not given here, because it does not seem to have any advantage over the method prescribed in US Federal Specification 0-P-559(Ref 6)... 

Tag closed tester—apparatus for determining the flash point of petroleum liquids having a viscosity below 5.8 centistokes (cSt) at 37.8°C (100°F) and a flash point below 93°C (200°F), under test methods prescribed in ASTM D 56. The test sample is heated in a closed cup at a specified constant... 

Table 5.4 summarizes common acceptance criteria for laboratory QC checks. Laboratories rarely exceed these method-prescribed criteria for trace element and inorganic analyses. For organic analyses, laboratories generate their own acceptance criteria by means of statistical control charts as described in Chapter 4.6.1.3. 

Separations of antibiotics were studied thoroughly. An IPC method using per-fluorocarboxylic acids as IPRs and pulsed electrochemical detection was devised to analyze gentamicin and performed better than the official method prescribed by the European Pharmacopoeia [78]. 

The oil after heating shall be bland and free from beany, rancid, painty, musty, soapy, fishy, metallic, and other undesirable or foreign flavors and odors when tested by the method prescribed in footnote m within 7 days after packaging each lot. 

The resistance to acidic and alkaline solutions is tested on compact glass fragments of know n surface area by boiling in the respective solution and by determining the loss in weight. In addition to this, there ate a number of special methods prescribed in the standard specifications. ... 

For the release of crospovidone sometimes this GC method is preferred instead of the HPLC method prescribed in the Crospovidone monograph of Ph.Eur. because the components vinylpyrrolidone and 2-pyrrolidone can be determined in one GC chromatogram and the use of methanol can be avoided. 

The above benchmark analysis of 29-month data from the Seychelles Child Development Study strongly supports the MRL of 0.0003 mg/kg/day calculated by ATSDR in this profile. Similarly, addressing the Seychellois 66-month data from the perspective of using the mean value (15.3 ppm) of the highest exposure group in the study, a method prescribed in ATSDR s published guidance for MRL development (Chou et al. 1998), also results in an identical MRL. ATSDR therefore has high confidence that this level is protective of the health of all potentially exposed human populations. 

Many methods prescribed for TLC include the addition of concentrated ammonia solution. Here, the following is recommended Only use ammonia solution of the highest purity (e.g. Suprapur, Merck No. 1.05428), order the smallest package size (250 ml) and always store bottles that have been opened in the refrigerator. Leftover amounts of other than TLC it is much better to open a fresh bottle of solvent. If there is too little ammonia gas dissolved in the aqueous phase, experimental results will not be reproducible. 

As regards abridged notation and nomenclature of alloys, we shall conform to the methods prescribed by the Permanent Commission of Standardisation in Paper A2, July 28th, 1919, on The Unification of Nomenclature of Metallurgical Products. ... 

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