Tube methods

Quartz Tube Method the sample is burned in a quartz tube and a stream of purified air carries the combustion gases into a hydrogen peroxide solution. 

A general limitation of the relaxation teclmiques with small perturbations from equilibrium discussed in the previous section arises from the restriction to systems starting at or near equilibrium under the conditions used. This limitation is overcome by teclmiques with large perturbations. The most important representative of this class of relaxation techniques in gas-phase kinetics is the shock-tube method, which achieves J-jumps of some 1000 K (accompanied by corresponding P-jumps) [30, and 53]. Shock hibes are particularly... 

The only disadvantage is that the procedure does not give accurate results if the compound sublimes the capillary tube method should be used in such cases, and it may be necessary to employ a sealed capillary tube. This apparatus should find a place in every laboratory. It is... 

With some acids (e.g., succinic acid and sulplianilic acid) more satisfactory results are obtained by reversing the order of mixing, i.e., by adding the solution of the so um salt of the acid to the reagent. It should be pointed out that the melting points of the derivatives as determined on the electric hot plate (Fig. II, 11, 1) may differ by 2-3° from those obtained by the capillary tube method. In view of the proximity of the melting points of the derivatives of many acids, the mixed m.p. test (Section 1,17) should be applied. 

Dissolve 1.000 g Rh by the sealed-tube method described under iridium. 

Fig. 14. Soladasli gel techniques for overcladding where TEOS = (C21150)481 (a) wet gel method and (b) rod-in-tube method.

Test Methods. Two basic types of test methods are commonly used to measure sound-absorption in test laboratories the reverberation room method and the impedance tube method. 

Because of this limitation the tube methods are used primarily for research and for appHcations where sound is iacident only normal to the surface of a material. 

Test Methodfor Impedance and Absorption of Acoustical Materials by the Impedance Tube Method, ASTM C384-90a, ASTM, Philadelphia, Pa., 1990. 

Methyl alcohol Charcoal tube method not recom mended. Use silica gel tubes. ... 

Generation of test atmospheres of organic vapours by the syringe injection technique Generation of test atmospheres of organic vapours by the permeation tube method On-site validation of sampling methods... 

MDHS 4 Generation of test atmospheres of organic vapours by the permeation tube method... 

Murray, S. W., Parasite tubing method of aeration, Spring Meeting of Rocky Mountain District, Division of Production, American Petroleum Institute, Paper No. 875-22-C, Calgary, Alberta, Canada, May 8-10, 1968. 

Storage under vacuum in a sealed tube (Method II). Substances that are extremely oxygen-sensitive, such as the fluorescent compound F of euphausiids and dinoflagellate luciferin, have to be stored in an evacuated sealed container at a low temperature. For long-term storage, they must be fuse-sealed in an evacuated glass vial using the method outlined below. 

The capillary tube method initially involves packing a powdered sample into a glass capillary tube of uniform diameter and length, carefully sealed at one end so that it forms a rounded tube of uniform thickness. The tube is then attached to a standardized thermometer so that the end of the tube reaches the middle of the thermometer reservoir bulb. This assembly is then inserted into a vessel contg a suitable liq which is uniformly heated so that the temp rises at a rate of about 1° per minute. Ref 1 discusses in detail equipment design and thermometer calibration. It should be noted that this technique is the method most widely used by organic chemists... 

Melting Point, Determination. Most methods for the detn of mp are microprocedures, and may be conveniently classified on the basis of the type of app used for the detn (1) the capillary tube method. (2) the heating bar method, and (3) the microscope heating stage (micro hot stage) method. 

From 500° to 760 °K. the impact tube method of Huber and Kan-trowitz (15) used nitrogen containing 0.05% water vapor. Their work on the relaxation of N2 in water yields P(N2 — H20)/P(N2 — N2) = 1100 at 560 °K., and their data are smaller than the calculated values by a factor of 4. The values of Lukasik and Young (17) are obtained from the resonance method between 770° and 1190 °K. using the sample containing <0.005% water. Their values at 1020° and 1186 °K. agree well... 

Hungate R E (1969) A roll tube method for cultivation of strict anaerobes. In Methods in Microbiology (Eds Norris and DW Ribbons), Vol 3B, pp 117-132. Academic Press, New York. 

Farng and Nelson [1] applied the capillary method to the determination of the diffusion coefficient of salicylic acid in the presence of polyelectrolytes. The reported variability in terms of the coefficient of variation ranged from 0.89% to 8.3%. Stout et al. [2] showed the tube method to be useful for determining diffusion coefficients of water-insoluble pharmaceuticals such as sulfonamides and steroids. The coefficient of variation associated with the diffusion coefficient for sulfisoxazole is 5.5%. 

P Stout, N Khoury, J Mauger, S Howard. Evaluation of a tube method for determining diffusion coefficients for sparingly soluble drugs. J Pharm Sci 75 65, 1986. 

Germanium in organometallic compounds can be determined by a modification of the combustion tube method. The sample is mixed with a large excess of chromic oxide, the organic elements are burnt in the tube and are absorbed downstream, whereas the... 

Several of these assays have become commercially available (see Table 3). The IA kit in a coated tube method [247], developed by Cape Technologies,has been made available for the analysis of various types of sample extracts (fly ash,... 

---