Test extract

Again, first carry out a small-scale test, extracting about 0 5 g. of the mixture with about 5 ml. of dil. HCl in a test tube, in order to determine whetner the neutral component is solid or liquid. 

Jump R.K., Sabey B.R. Soil test extractants for predicting selenium in plants. In Selenium in Agriculture and the Environment, L.M. Jacobs, ed. Madison, IL Soil Science of America, Inc. 1989. 

Mehlich A. Mehlich 3 soil test extractant—a modification of Mehlich 2 extractant. Com. Soil Sci. Plant Anal. 1984 15 1409-1416. 

A second SFE-based method for the extraction of NPEC from solid matrices is called subcritical (hot) water extraction [9], The method was applied for NPEi 4C in 0.25 g sludge samples. Subcritical water is used as the extraction solvent, with 30% ethanol as the modifier, yielding quantitative recoveries. Other tested extraction solvent compositions were C02, hot water, methanol-modified hot water, none of which were judged satisfactory. 

Ontario-grown American ginseng extracts were shown to have low total phenolic content in comparison to some previously tested extracts. Ontario ginseng samples ranged from 0.67 to 6.98 p,g quercetin equivalents/mg extract whereas values were in the order of 60-269 p,g quercetin equivalents/mg extract for plants known to be rich in phenolic compounds (such as quercetin, catechin, and other flavonoids) [21],... 

McIntosh, J.L. (1969) Bray and Morgan soil test extractants modified for testing acid soils from different parent materials. Agronomy Journal 61, 259-265. 

Mehlich, A. (1984) Mehlich 3 soil test extractant a modification of the Mehlich 2 extractant. Commununications in Soil Science and Plant Analysis 15(12), 1409-1416. 

Many tests are described in Ref 14 and following is the abstract of some tests Qualitative Tests. Pulverize the proplnt to test, extract it. with ether on methylene chloride (as described in MIL-STD-286A, Method 104.1 or in Vol 2 of Encycl, p C131-L) and evaporate the solvent using a stream of dry air. Place ca 1 mg of this residue on a spot plate and add a few drops of the reagent, such as de-... 

An alkaloid, epibatidin (173), has been isolated from skin of the Ecuadorian frog Epipedobates tricolor which exhibited a 200-fold potency compared with morphine as an analgesic in the Straub-tail test. Extracts from 750 frogs provided only 1 mg of the Straub-tail alkaloid. The researchers had to wait for a decade until more sensitive instruments... 

In testing extracts, it suffices to dissolve or dilute them with water. The solutions are subjected to the above tests, also to others described below for the detection of adulterations, and to those indicated" later for the more important separate extracts. From the commercial point of view, interest attaches also to the specific gravity of liquid extracts, this being measured with a hydrometer and usually expressed in degrees BaumA... 

Four factors have been varied in testing extraction of hafnium with... 

Overall, 75 out of 1000 (7.5%) extracts passed the 75% stringency requirement for at least one gene (Table 4.1). Sixty-eight plant families were screened, out of which 21 (30.8%) families containing 337 species produced 58 (12.9%) species hits (Table 4.1). The number of tested extracts was greater than the number of tested species because several plant parts from the same species were often extracted and tested (e.g., leaves and roots). 

ANALYSIS OF INHIBITOR GLYCOPROTEINS FROM BOVINE TESTES EXTRACT... 

Experiment . Selectivity Blank Test Extract selectivity blanks from six different lots. 

Experiment 2. Selectivity LLOQ Test Extract selectivity LLOQ at replicate of one from six different lots. 

Experiment 3. Matrix Factor (MF) Test Extract six blanks from six different lots. Spike appropriate and same amount of analyte and IS into the postprocessed extract and neat sample, respectively. MF is the ratio of the peak area of the analyte in extract vs. neat sample. For stable labeled IS, the response can be normalized and peak area ratio (instrument response) can be used for MF calculation. For analog IS, the matrix factor must be calculated individually for analyte and IS. The recommended concentration for MF test is at medium QC level. 

In vitro tests in bacteria, for example the well-known Ames test, and tests in mammahan cells are used to show if a chemical is able to damage DNA and cause a mutation, fn the bacterial tests, extracts from mammalian liver (usually from a rat) have to be added to provide the enzymes that convert chemicals into products that might react with DNA. 

Garter snakes respond to prey extracts with tongue flicking and attempts to bite (Gove and Burkhardt 1975). Test extracts of different prey animals such as earthworms, slugs, crickets, or leeches. Dip cotton balls or Q-tips into extracts and present to captive snakes. Experimenter should be behind screen to minimize snake s responses to light or movement. 

For the first two tests, extracts that are similar to those used during physicochemical testing are used. The extraction process, which differs somewhat from previous extractions, is explained in the USP. The first test, the systemic injection test, uses a sample of extract injected intravenously or intraperitoneally (as indicated in the test protocol) into each of five albino mice. Note that a control solution is used to inject five mice in a control group as well. Animals are evaluated over the next three days and monitored for death, abnormal behavior, or weight loss. If the test results are inconclusive, the protocol can be repeated on groups of 10 mice each. 

In these tests, extraction efficiency may be expressed in terms of a Murphree efficiency as... 

Cypridina luciferin is extremely unstable in air. After some test extractions of the luciferin from dried Cypridina, I made a plan to extract 500 g of dried Cypridina in the absence of air to obtain 2-3 mg of purified material for crystallization. It was 10 times the amount used at Princeton, and I thought the plan must succeed if the compound was crystallizable. Professor Hirata agreed to the plan and his glass blower made an over-sized soxhlet apparatus for me. 

The best extraction procedure is hardly predictable, due to the differences in types of soil and in the presence of the contaminants. Developing a new method should therefore compare the different potential methods. As mentioned before, it is not enough to measure only recoveries. The added compounds are easily accessible to the extractant and may even be extracted with a poor method. Certified reference materials (CRMs) are available for a variety of classes of compounds. Even if not all the analytes of interest are present in a CRM, the analyses may give a good indication of the capabilities of a tested extraction procedure. A further check of the extraction efficiency can be achieved by extracting the residual soil with other exhaustive procedures like Soxhlet. If the amount found is negligible compared to the amount obtained in the first extraction, it may be concluded that the first one is sufficient. Extraction methods that can be used are ... 

Test material The actual material being studied. For example, if the concentration of a solution is being analyzed it is called a test solution, if it is an extract that is being analyzed it is a test extract. The use of the word sample is not encouraged because of confusion with the statistical concept of a sample. (Section 2.3)... 

There is a small problem here experienced only by chemists. We tend to call each thing that we analyze a sample, so have a firm idea that we have n samples that give our n data. Statistics refers to the n data as the sample to distinguish it from the infinite population. The International Union of Pure and Applied Chemistry (IUPAC) has recommended that the actual material being studied should be a description of the material preceded by the word test, for example test solution or test extract, and the word sample be reserved for its statistical sense. Although we shall try to adhere to this convention in this book, many scientists will find it almost impossible to not refer to a test solution as a sample. 

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