Description of Method

Dioxane is freshly distilled from a benzophenone-sodium mixture, or, as is more convenient for routine analysis, is used without further purification when obtained as an analytical grade reagent. 

Boron trifluoride etherate is freshly distilled over CaH2 or used directly when obtained as an analytical grade chemical. This reagent is kept at 4°C under nitrogen as it is a moisture-sensitive reagent. 

Ethanethiol and HBF4 etherate, which replaces BF, etherate in the thioacidolysis of acetylated samples, are of analytical grade quality. 

The thioacidolysis reagent is prepared immediately before use 2.5ml of BF, etherate and 10 ml of ethanethiol are successively introduced into a 100-ml volumetric flask containing 20ml of dioxane and the final volume is adjusted to 100 ml with dioxane. This reagent is therefore a solution of 0.2 M BF-, etherate (Note 1) in a 8.75 1 (v/v) dioxane/ethanethiol mixture. It is a colorless reagent immediately after preparation. When an inferior grade of dioxane is used, a yellow color is observed this reagent is not suitable for analytical use. 

---

Description of Method. Iron in the +2 oxidation state reacts with... 

Description of Method. Copper and zinc are isolated by digesting tissue samples after extracting any fatty tissue. The concentration of copper and zinc in the supernatant are determined by atomic absorption using an air-acetylene flame. 

Description of Method. Quinine is an alkaloid used in treating malaria (it also is found in tonic water). It is a strongly fluorescent compound in dilute solutions of H2SO4 (f = 0.55). The excitation spectrum of quinine shows two absorption bands at 250 nm and 350 nm, and the emission spectrum shows a single emission band at 450 nm. Quinine is rapidly excreted from the body in urine and is easily determined by fluorescence following its extraction from the urine sample. 

Description of Method. Salt substitutes, which are used in place of table salt for individuals on a low-sodium diet, contain KCI. Depending on the brand, fumaric acid, calcium hydrogen phosphate, or potassium tartrate also may be present. Typically, the concentration of sodium in a salt substitute is about 100 ppm. The concentration of sodium is easily determined by flame atomic emission. Because it is difficult to match the matrix of the standards to that of the sample, the analysis is accomplished by the method of standard additions. 

Description of Method. Adding BaC to an acidified sample precipitates S04 a BaS04. The concentration of S04 may be determined either by turbidimetry or nephelometry using an incident source of radiation of 420 nm. External standards containing known concentrations of S04 are used to standardize the method. 

Description of Method. The amount of chlorpromazine in a pharmaceutical formulation is determined voltammetrically at a graphite working electrode in a nonstirred solution. Calibration is achieved using the method of standard additions. 

Description of Method. Fluoxetine, whose structure is shown in Figure 12.31a, is another name for the antidepressant drug Prozac. The determination of fluoxetine and its metabolite norfluoxetine. Figure 12.31 b, in serum is an important part of monitoring its therapeutic use. The analysis is complicated by the complex matrix of serum samples. A solid-phase extraction followed by an HPLC analysis using a fluorescence detector provides the necessary selectivity and detection limits. 

Description of Method. The water-soluble vitamins Bi (thiamine hydrochloride), B2 (riboflavin), B3 (niacinamide), and Be (pyridoxine hydrochloride) may be determined by CZE using a pH 9 sodium tetraborate/sodlum dIhydrogen phosphate buffer or by MEKC using the same buffer with the addition of sodium dodecyl-sulfate. Detection Is by UV absorption at 200 nm. An Internal standard of o-ethoxybenzamide Is used to standardize the method. 

Description of Method. Creatine is an organic acid found in muscle tissue that supplies energy for muscle contractions. One of its metabolic products is creatinine, which is excreted in urine. Because the concentration of creatinine in urine and serum is an important indication of renal function, rapid methods for its analysis are clinically important. In this method the rate of reaction between creatinine and picrate in an alkaline medium is used to determine the concentration of creatinine in urine. Under the conditions of the analysis, the reaction is first-order in picrate, creatinine, and hydroxide. 

Description of Method. The FIA determination of phosphate is an adaptation of a standard spectrophotometric analysis for phosphate. In the presence of add, phosphate reacts with molybdate to form a yellow-colored complex in which molybdenum is present as Mo(VI). 

Monitoring and Control. Detailed descriptions of methods used for handling and monitoring tritium at Savaimah River (76,77) and the European Tritium Handling Program (78) have been pubHshed. 

The RMDB consists of two mayor sections computer data storage and retrieval system, and backup microfilm data bank file. The computer data storage and retrieval system is used for die standard reliability and maintainability data listing, special calculations, and searches. This data bank system has been established to facilitate remote terminal access compatible with the GIDEP remote terminal programs. The microfilm data bank file is used for storage and distribution of supplier s documents, failure analysis curves, description of methods used in the collection of the data, and additional background information too extensive to include in the computer data bank. 

A detailed description of methods for studying dynamic (i.e. time-dependent) phenomena and condensed phases is outside the scope of this book. The common feature for all these methods, however, is the need for an energy surface upon which the dynamics can take place. The generation of such a surface normally relies at least partly on results from calculations of the types discussed in Chapters 2-6, and it may therefore be of interest to briefly discuss the fundamentals. 

Harvey, E. N. (1926b). Oxygen and luminescence, with a description of methods for removing oxygen from cells and fluids. Biol. Bull. 51 89-97. 

Techniques used in experimental measurements of reaction rates are reviewed in Vol. 1 of this series, including specific descriptions of methods used to study homogeneous and heterogeneous rate processes by Batt [112] and by Shooter [113]. A number of experimental approaches to the investigation of reactions of solids are described by Budnikov and Ginstling [1]. 

Description of Method Its Specificity, Usefulness, and Possible Drawbacks 175... 

As far as is practicable, the methods proposed must employ the simplest approach and commonly available equipment. If possible, standard multi-residue methods should be used. Descriptions of methods must be provided, including all necessary details. 

Sulfonylurea herbicides are generally applied to crops as an early post-emergent herbicide. Crops that are tolerant to these herbicides quickly metabolize them to innocuous compounds. At maturity, residues of the parent compound in food and feed commodities are nondetectable. Metabolites are not considered to be of concern, and their levels are usually nondetectable also. For this reason, the residue definition only includes the parent compound. Tolerances [or maximum residue limits (MRLs)] are based on the LOQ of the method submitted for enforcement purposes and usually range from 0.01 to 0.05 mg kg (ppm) for food items and up to O.lmgkg" for feed items. There is no practical need for residue methods for animal tissues or animal-derived products such as milk, meat, and eggs. Sulfonylurea herbicides are not found in animal feed items, as mentioned above. Furthermore, sulfonylurea herbicides intentionally dosed to rats and goats are mostly excreted in the urine and feces, and the traces that are absorbed are rapidly metabolized to nontoxic compounds. For this reason, no descriptions of methods for animal-derived matrices are given here. 

The purpose of this compilation is to tabulate the densities of compounds, hence only minimal description of experimental methods used to measure the density of liquids or solids appears. Detailed descriptions of methods for density determination of solids, liquids and gases, along with appropriate density reference standards, appear in a chapter by Davis and Koch in Physical Methods of Chemistry, Volume VI, Determination of Thermodynamic Properties [86-ros/bae],... 

Dinkelaker B., Hahn G., Romheld V., Wolf G.A, Marschner H. Non-destructive methods for demonstrating chemical changes in the rhizosphere 1. Description of method. Plant Soil 1993 155/156 67-70. 

Copy of the protocol/amendments (title of study purpose, including expected benefits obtained by doing the study participant selection criteria par ticipant exclusion criteria study design, including as needed, a discussion of the appropriateness of research methods description of methods performed)... 

---