Disclosed is a method for the determination of impurities in polyalkylene ethers and polyalkylene amines comprising the steps i) introducing polyalkylene ethers or polyalkylene amines as an analyte into a chromatography column containing monolithic silica gel as a stationary phase, ii) eluting the analyte with a liquid elution agent having such a polarity that the analyte is in adsorptive equilibrium with the stationary phase during chromatography, iii) detecting the components of the analyte at the exit-side end of the chromatography column, receiving a chromatogram, which shows different components of the analyte and its qualitative amount depending on the elution time of the individual components, and iv) identifying bands in the chromatogram having a low height or area compared to the band with the largest height or area as an indication of the presence of impurities in the analyte.

The method allows in an easy manner to identify impurities in the sample. The method can be used for quality control but also for the preparative cleaning of the sample.

A method for analyzing related substances in a pharmaceutical composition containing an amphiphilic block copolymer comprising a hydrophilic block and a hydrophobic block as a polymeric drug carrier, related substances identified thereby, and a method for evaluating a pharmaceutical composition by using the same are provided. Preferably, the method comprises evaluating a polymeric micelle pharmaceutical composition, which comprises an amphiphilic block copolymer comprising a hydrophilic block (A) and a hydrophobic block (B), and paclitaxel or docetaxel as a poorly water-soluble drug, by using a compound represented by Chemical Formula 1, wherein the hydrophilic block (A) comprises one or more selected from the group consisting of polyethylene glycol or derivatives thereof, polyvinylpyrrolidone, polyvinyl alcohol, polyacrylamide and combinations thereof; and the hydrophobic block (B) is polylactide.

The present invention discloses a method for initiating a graphene oxide (GO) through reduction by a reductant to controllably release organic compounds, comprising the following steps: (1) mixing GO and a buffer solution; (2) further mixing with a sewage containing organic contaminants; (3) conducting solid-liquid separation, mixing the solid phase and the pure, introducing and N.sub.2; (4) further adding the reductant; (5) conducting sequential batch kinetics experiment. The present invention utilizes the size effect and polarity control of GO to selectively adsorb aromatic organic contaminants in sewage and fully transfer the selectively adsorbed organic contaminants from a large amount of sewage to a small amount of pure water by initiating using the reductant, and no extraction of the organic phase is required, the time for purification is reduced, and the energy consumption for purification is also reduced.

The present invention discloses a pollutant generation system. The pollutant generation system includes a pollution source and a pollutant emitter. The pollutant emitter is connected to the pollution source. The pollution source is composed of two gases including air and methane. The flows of the gases are strictly controlled. Then, the gases enter a magnetic bead glass bottle. Due to the disturbance of magnetic beads to the flowing of the gases, the gases are sufficiently disordered, and the two gases are sufficiently mixed by using a spiral tube to generate a uniform and stable pollution source.

The present invention relates to methods of determining the purity of a sample of 3,4-diaminopyridine comprising determining the presence, absence, or amount of a dimer of 3,4-diaminopyridine or a dimer of 3,4-diaminopyridine in the form of a salt, solvate or complex or a combination thereof. The invention also relates to methods of detecting and quantitating degradation in a sample of 3,4-diaminopyridine. Dimers of 3,4-diaminopyridine and methods of making and isolating the same are also provided.

This invention provides an isolated compound having the structure:

##STR00001##

or, or a salt thereof.

The invention also provides for a process for preparing 4-(3-(methylsulfonyl)phenyl)-1-propylpiperidin-4-ol, 1-(3,3-bis(3-(methylsulfonyl)phenyl)propyl)-4-(3-(methylsulfonyl) phenyl)piperidone, 1,4-bis((3-(1-propylpiperidin-4-yl)phenyl)sulfonyl)butane, (3R,4S)-4-(3-(methylsulfonyl)phenyl)-1-propylpiperidin-3-ol, 4-(3-(methylsulfonyl)phenyl)-1-propylpiperidine 1-oxide, 1-(2-methylpentyl)-4-(3-(methylsulfonyl)phenyl)piperidine, 4-(3-(methylsulfinyl)phenyl)-1-propyl-1,2,3,6-tetrahydropyridine, and 4-(3-(methylsulfonyl)phenyl)-1-propyl-1,2,3,6-tetrahydropyridine.

This invention also provides an impurity or a salt thereof for use, as a reference standard to detect trace amounts of the impurity in a pharmaceutical composition comprising pridopidine or a pharmaceutically acceptable salt thereof. This invention further provides a process for producing a pridopidine drug product comprising obtaining a pridopidine drug substance and mixing the pridopidine drug substance with suitable excipients so as to produce the pridopidine drug product. This invention also provides a process for producing a pridopidine drug product. This invention also provides a process of distributing a pridopidine drug product.

The present invention discloses a method for initiating a graphene oxide (GO) through reduction by a reductant to controllably release organic compounds, comprising the following steps: (1) mixing GO and a buffer solution; (2) further mixing with a sewage containing organic contaminants; (3) conducting solid-liquid separation, mixing the solid phase and the pure, introducing and N.sub.2; (4) further adding the reductant; (5) conducting sequential batch kinetics experiment. The present invention utilizes the size effect and polarity control of GO to selectively adsorb aromatic organic contaminants in sewage and fully transfer the selectively adsorbed organic contaminants from a large amount of sewage to a small amount of pure water by initiating using the reductant, and no extraction of the organic phase is required, the time for purification is reduced, and the energy consumption for purification is also reduced.

To analytically determine concentration of dissolved gases in a water pipeline, a water sample is drawn from a source carrying water with dissolved gas, through a water source port of a four-way valve. The water sample is flowed from the water source port towards a syringe port of the valve and into a syringe fluidically coupled to the syringe port to hold the water sample. Inert gas is drawn through an inert gas port of the valve from an inert gas source and is flowed from the inert gas port towards the syringe port and into the syringe. A mixture of the water sample and the inert gas is flowed from the syringe port towards an analyzer port of the valve and into an analyzer fluidically coupled to the analyzer port.

The disclosure relates to a recycling chromatography method that includes injecting a sample into a mobile phase flow stream of a chromatography system to create a combined flow stream. The sample includes an API and at least one impurity. The chromatography system includes a first column and a column in series, a first valve in fluid communication with the first and second chromatographic columns, a heater in communication with the first and second chromatographic columns, a fraction collector in fluid communication with the first and second chromatographic columns, and a second valve positioned before the fraction collector. The combined flow stream is recycled from the first chromatographic column to the second chromatographic column and vice versa by switching the first valve until a baseline resolution is achieved to separate the at least one impurity from the API. The at least one impurity is collected in the fraction collector.

This invention provides an isolated compound having the structure: ##STR00001##
or a salt thereof. The invention also provides for a process for preparing 4-(3-(methylsulfonyl)phenyl)-1-propylpiperidin-4-ol, 1-(3,3-bis(3-(methylsulfonyl)phenyl)propyl)-4-(3-(methylsulfonyl) phenyl)piperidone, 1,4-bis((3-(1-propylpiperidin-4-yl)phenyl)sulfonyl)butane, (3R,4S)-4-(3-(methylsulfonyl)phenyl)-1-propylpiperidin-3-ol, 4-(3-(methylsulfonyl)phenyl)-1-propylpiperidine 1-oxide, 1-(2-methylpentyl)-4-(3-(methylsulfonyl)phenyl)piperidine, 4-(3-(methylsulfinyl)phenyl)-1-propyl-1,2,3,6-tetrahydropyridine, and 4-(3-(methylsulfonyl)phenyl)-1-propyl-1,2,3,6-tetrahydropyridine. This invention also provides an impurity or a salt thereof for use, as a reference standard to detect trace amounts of the impurity in a pharmaceutical composition comprising pridopidine or a pharmaceutically acceptable salt thereof. This invention further provides a process for producing a pridopidine drug product comprising obtaining a pridopidine drug substance and. mixing the pridopidine drug substance with suitable excipients so as to produce the pridopidine drug product. This invention also provides a process for producing a pridopidine drug product. This invention also provides a process of distributing a pridopidine drug product.