Test sample, definition

Only in a few cases are test samples measurable without any treatment. As a rule, test samples have to be transformed into a measurable form that optimally corresponds to the demands of the measuring technique. Therefore, sample preparation is a procedure that converts a test sample into a measuring sample. Whereas test samples represent the material in its original form, measuring samples embodies a form that is able to interact with the measuring system in an optimum way. In this sense, measuring samples can be solutions, extracts, pellets, and melt-down samples, but also definite surface layers and volumes in case of micro- and nanoprobe techniques. 

Sample preparation is directed to the conversion of test samples in a physically and chemically measurable form. The measuring sample can require a definite state (gaseous, liquid, or solid) or form (aqueous or organic solution, melt-down tests, and pellets). In other cases, measuring samples have to become diluted or enriched to get an optimum concentration range. It may also be necessary to remove interfering matrix constituents which disturb the determination of the analyte. 

Flammability Index — 138 seconds. Its definition is given in this Vol, under F s Fragmentation Test Sample of 95/5-EDNA/... 

Reduction. The nitro compound is reduced by means of a concentrated solution of sodium hydrosulfide, NaSH, the preparation of which was described on page 113. A test is made in the following way to determine how much of the reducing agent is required 25 cc. of the filtered solution of the nitro compound is pipetted into a 750-cc. Erlen-meyer flask, diluted with 350 cc. hot water, and neutralized with soda to the point where the red coloration, which is formed, just persists. A sodium hydrosulfide solution, prepared by diluting 10 cc. of the concentrated solution to 100 cc., is then added, at 60-70°, from a burette until the color of the solution turns to a piure blue. Additional 1-cc. portions of the hydrosulfide solution are added until a definite blackening is obtained when the colorless spot on filter paper, formed by a salted-out test sample, is treated with ferrous sulfate. From the amount of hydrosulfide used in the test determination, the amount required for the total volume of the nitro solution is calculated. 

It is best to make a large quantity of total RNA from the control cell line (SW620), to be included in every PCR reaction. Typically, the maximum concentrations which allow exponential amplification at 30 cycles for SW620 are cDNA derived from 125 ng input RNA (a 1 8 dilution from the 1 jug RT reaction) for MDR-1 mRNA cDNA derived from 3.91 ng RNA (a 1 256 dilution from the 1 pg RT reaction) for MRP mRNA and cDNA derived from 0.49 ng RNA (a 1 2048 dilution from the 1 pg RT reaction) for p2-microglobulin mRNA. For quantitation of each of these in unknown samples, an initial test PCR reaction is performed using an amount of RNA/cDNA equivalent to that used from SW620. Optimal dilutions of the test sample cDNA for a definitive... 

The nonreproducibility of data implies that the tests and the meaning of the term "sensitivity" need further study and understanding [6]. Questions arise as to whether certain tests actually measure the effect of the specified stimulus, even as one among several stimuli directed at the test sample by the apparatus. Kistiakowsky and Connor [1] concluded that a definite mechanical sensitivity of an explosive was not found. Koenen et al. [2] and Afanas ev and Bobolev [5] also concluded that an intrinsic impact sensitivity of an explosive does not exist, but is a function of the test method, container, compression, arrangement of the sample, state of the sample tested, its method of preparation, particle size and shape, and possibly the climactic conditions during testing. By extension these factors can also be expected to affect sensitivities to other stimuli. 

The method performance study focuses on the analytical method. In order to achieve a constructive work the organiser should assure that the method to be used by the participants has been investigated in detail prior to the start of the interlaboratory study. This preliminary investigation should be undertaken by a senior analyst. It should lead to a detailed draft analytical protocol, to a clear definition of the type and number of samples to be distributed and analysed, to indications on the repeatability of the method and its long-term reproducibility. In parallel, a study on the production of proper samples should be undertaken. Additional materials can also be prepared, e.g. calibration tools (pure calibrants or solutions), or blanks with a similar matrix than the test sample, spiked materials, etc. 

The objective of a definitive or a relative quantitative analytical procedure is to quantify as accurately as possible each of the unknown quantities that the laboratory intends to measure. In other words, a laboratory should expect the difference between the observed/measured value (X) and the unknown true value (/iT) of the test sample to be small or within an acceptance limit X ... 

Electrochemical monitoring of these compounds has definite advantages. For example, wide concentration ranges are measurable without dilution simply by scale switching and the test sample does not need to be optically clear. Many of these methods have utilized enzyme-catalyzed reactions because of the specificity of such reactions. Many reports on applications of enzyme electrodes in clinical and food analysis have been published (1,2). However, enzymes are generally expensive and unstable. Recently many methods have been developed for immobilization of whole cells... 

Estimation of trueness and precision The EU directive (Council Directive 98/83/EC, 1998) refers to the definitions for the determination of trueness and precision given in ISO 5725-1 (ISO, 2002). According to this standard, the estimation of the trueness requires a large series of replicate determinations of test samples. But what does Targe series mean Neither ISO 5725-1 nor the EU directive resolve this question. The determination of precision also requires a number of replicate determinations of a test sample. Information on a recommended number of replicates is also missing in ISO 5725-1. 

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