Interference procedure

In summation, the following points should be observed or at least considered by inventors. Although this is not an exhaustive listing of interference procedure, each point is substantially under the control of an inventor, and proper attention to them will strengthen his priority position. 

A record like this is of immense help to patent attorneys or agents in preparing patent applications, but also, if properly dated and witnessed, it may establish a provable date in an interference procedure. Thus, again, a routinely applied signature and witnessing procedure may convert a conception record, as well as a lab notebook, into a document of high legal value. 

While the above-mentioned estimates assume that the patenting process is rather straightforward, considerable expenses must be anticipated if an opposition has been filed, or if an interference is to be expected in the USA. Due to the complicated procedure, especially of a US patent interference, several ten or hundred thousand dollars are spent readily and the entire cost of an interference procedure may well... 

Bender Gestalt Test without and with the Canter Background Interference Procedure. 

Evolution profiles were constructed as plots of net IR absorbance against temperature for selected absorption bands which were known to be free from interferences. Procedures used for data reduction and calculation of temperatures appropriate to absorption bands of interest were as described previously [4], except that absorbances were normalised to 10 mg sample mass to allow direct comparison of profiles. 

This procedure can be applied to most P2P mixes but is especially effective on the methods to follow. However, in super clean methods, such as the PdCl2 below, where lots of isosafrole is produced, the iso byproduct can interfere with crystal formation. Someone-Who-ls-Not-Strike once found that when an appreciable amount of isosafrole was formed to the detriment of MD-P2P, the oil screwed up the crystal matrix disallowing it to form. Confused, the chemist tried to rescue the uncrystallized oil from the aqueous solution by extracting out the oil to try other things. But when the solvent hit the solution, the P2P crystallized out. Go figure The... 

Note Additional procedural information plus interferences and general remarks will be found in J. A. Dean, ed.. Analytical... 

Examine a procedure from Standard Methods for the Analysis of Waters and Wastewaters (or another manual of standard analytical methods), and identify the steps taken to compensate for interferences, to calibrate equipment and instruments, to standardize the method, and to acquire a representative sample. 

An analysis to determine the concentration of Cu in an industrial plating bath uses a procedure for which Zn is an interferent. When a sample containing 128.6 ppm Cu is carried through a separation to remove Zn, the concentration of Cu remaining is 127.2 ppm. When a 134.9-ppm solution of Zn is carried through the separation, a concentration of 4.3 ppm remains. Calculate the recoveries for Cu and Zn and the separation factor. 

The amount of Co in an ore sample is to be determined using a procedure for which Fe is an interferent. To evaluate the procedure s accuracy, a standard sample of ore known to have a Co/Fe ratio of 10.2 1 is analyzed. When pure samples of Co and Fe are taken through the procedure, the following calibration relationships are obtained... 

The amount of calcium in a sample of urine was determined by a method for which magnesium is an interferent. The selectivity coefficient, Rca.Mg> for the method is 0.843. When a sample with a Mg/Ca ratio of 0.50 was carried through the procedure, an error of-3.7% was obtained. The error was +5.5% when a sample with a Mg/Ca ratio of 2.0 was used. 

Chloride ion is known to quench the intensity of quinine s fluorescent emission. For example, the presence of 100 ppm NaCI (61 ppm Ch) gives an emission intensity that is only 83% of that without chloride, whereas the presence of 1000 ppm NaCI (610 ppm Ch) gives a fluorescent emission that is only 29% as intense. The concentration of chloride in urine typically ranges from 4600 to 6700 ppm Ch. Flow is an interference from chloride avoided in this procedure ... 

Dissolved O2 is a problem when scanning toward more negative potentials where its reduction can lead to a significant cathodic current. In this procedure we are scanning toward more positive potentials and generating anodic currents thus, dissolved O2 is not an interferent. 

Because the higher alcohols are made by a number of processes and from different raw materials, analytical procedures are designed to yield three kinds of information the carbon chain length distribution, or combining weight, of the alcohols present the purity of the material and the presence of minor impurities and contaminants that would interfere with subsequent use of the product. Analytical methods and characterization of alcohols have been summarized (13). 

Two methods are used to measure pH electrometric and chemical indicator (1 7). The most common is electrometric and uses the commercial pH meter with a glass electrode. This procedure is based on the measurement of the difference between the pH of an unknown or test solution and that of a standard solution. The instmment measures the emf developed between the glass electrode and a reference electrode of constant potential. The difference in emf when the electrodes are removed from the standard solution and placed in the test solution is converted to a difference in pH. Electrodes based on metal—metal oxides, eg, antimony—antimony oxide (see Antimony AND ANTIMONY ALLOYS Antimony COMPOUNDS), have also found use as pH sensors (8), especially for industrial appHcations where superior mechanical stabiUty is needed (see Sensors). However, because of the presence of the metallic element, these electrodes suffer from interferences by oxidation—reduction systems in the test solution. 

Ozone can be analyzed by titrimetry, direct and colorimetric spectrometry, amperometry, oxidation—reduction potential (ORP), chemiluminescence, calorimetry, thermal conductivity, and isothermal pressure change on decomposition. The last three methods ate not frequently employed. Proper measurement of ozone in water requites an awareness of its reactivity, instabiUty, volatility, and the potential effect of interfering substances. To eliminate interferences, ozone sometimes is sparged out of solution by using an inert gas for analysis in the gas phase or on reabsorption in a clean solution. Historically, the most common analytical procedure has been the iodometric method in which gaseous ozone is absorbed by aqueous KI. 

The hberated iodine is measured spectrometricaHy or titrated with Standard sodium thiosulfate solution (I2 +28203 — 2 1 VS Og following acidification with sulfuric acid buffers are sometimes employed. The method requires measurement of the total gas volume used in the procedure. The presence of other oxidants, such as H2O2 and NO, can interfere with the analysis. The analysis is also technique-sensitive, since it can be affected by a number of variables, including temperature, time, pH, iodide concentration, sampling techniques, etc (140). A detailed procedure is given in Reference 141. 

The ease of hydrolysis of metal alkoxides makes metal analysis a comparatively simple task. In many cases, the metal may be estimated by hydrolysis of a sample in a cmcible, and ignition to the metal oxide. Alternatively, the metal ion may be brought into solution by hydrolysis of a sample with dilute acid, followed by a standard analytical procedure for a solution of that particular metal. If the alcohol Hberated during the hydrolysis is likely to cause interference, it may be distilled from the solution by boiling. 

A double end point, acid—base titration can be used to determine both sodium hydrosulfide and sodium sulfide content. Standardized hydrochloric acid is the titrant thymolphthalein and bromophenol blue are the indicators. Other bases having ionization constants in the ranges of the indicators used interfere with the analysis. Sodium thiosulfate and sodium thiocarbonate interfere quantitatively with the accuracy of the results. Detailed procedures to analyze sodium sulfide, sodium hydro sulfide, and sodium tetrasulfide are available (1). 

Calcium and magnesium can be titrated readily with disodium ethylenediaminetetraacetate, with Eriochrome Black T as the indicator. The solution is buffered at pH 10.0. Certain metal ions interfere with this procedure by causing fading or indistinct end points. Cyanide, sulfide, or hydroxjiamine can be used to eliminate or minimise the interferences. 

Several colorimetric procedures for fluoride are available, but it is usually desirable to distill the sample from concentrated sulfuric acid prior to analysis to eliminate interferences. One method is based upon bleaching a dye formed by the reaction of zirconium and sodium 2-(p-sulfophenylazo)-l,8-dihydroxy-3,6-naphthalenedisulfonate (SPADNS reagent) (28). 

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