Endpoint determination drying

Whether the application is drying a slurry, powder or granulation, the ultimate goal is achievement of some solvent level appropriate for transfer of the dried material to a subsequent process step. Thus, a method of endpoint determination is crucial to the economic success of the drying step as well as to the endowment of the proper physical characteristics on the dried material. For example, over-drying may result in unwanted static charge or reduced particle size due abradement of particles. 

Perhaps the be.st known method of endpoint determination is thermogravimetric analysis or loss on drying analysis. This method requires an operator to stop the process and gather a representative sample for analysis. The drying process resumes while the sample is analyzed po.sing the po.ssibility that the material may exceed the acceptable endpoint while the analysis is made. Loss on drying is not specific to a particular component as all volatile components are driven off in the analysis. 

Karl Fischer titrimetry is another endpoint determination method requiring collection of samples from the dryer. This analytical method is more sophisticated than simple loss on drying. It is also more costly, more time consuming and exposes employees to dangerous chemicals. Expenditures are also necessary for the chemical reagents and the safe disposal of these reagents. 

Notes Ecotoxicological tolerance values are based on die EC20 values for growth toxicity endpoints (shoot dry mass) reported in Tables 12.1 and 12.2. ND = not determined (no data available). 

Considerations of model validation for the prediction of water loss during drying were studied by Peinado et al. [31]. Authors describe the approach they took to determine the figures of merit required by external guidelines and discuss some of the interpretations of the published methods to accommodate the accuracy of the endpoint determination. 

Hettenbach, K., David, J., Dias, E., Brenek, S., Laforte, C. and Barnett, S. Microwave assisted vacuum drying and endpoint determination using mass spectrometry, part 1. Org. Process Res. Dev. 8 2004. (Introduction). 

One 1-ml aliquot is added to 1.0 ml of freshly-distilled 1,2-dibromo-ethane (bp 132°C) in an oven-dried flask which contains a static atmosphere of nitrogen or argon. After the resulting solution has been allowed to stand at 25°C for 5 min, it Is diluted with 10 rat of water and titrated for base content (residual base) to a phenolphthalein endpoint with standard 0.100 M hydrochloric acid. The second 1-mL aliquot is added cautiously to 10 ml of water and then titrated for base content (total base) to a phenol phthalein endpoint with standard aqueous 0.100 M hydrochloric acid. The methyllithium concentration is the difference between the total base and residual base concentrations.2 Alternatively, the methynithiura concentration may be determined by titration with a standard solution of sec-butyl alcohol employing 2,2 -bipyridyl as an indicator. 

The concentration of the Grignard reagent solution is determined by titration. An oven-dried, 10-mL flask with septum is charged with 1 mg of phenanthroline and 3.0 mL of the reaction mixture. 2-Methylpropanol is added until the red-purple color is dissipated and a yellow endpoint is reached. The yield of Grignard reagent is 0.184 mol (70%). 

Mammalian cells in culture are exposed to the test substance. Established cell lines are treated both with and without metabolic activation. Cells are incubated for an appropriate length of time, then rinsed, fixed, and dried. Slides are developed, stained, and exposed silver grains are counted. The endpoint of UDS is measured by determining the uptake of labeled nucleosides in cells that are not undergoing scheduled (S-phase) DNA synthesis. The most widely used technique is the determination of the uptake of H-TdR by autoradiography. Primary cultures (e.g., rat hepatocytes), human lymphocytes, or established cell lines (e.g., human diploid fibroblasts) may be used in the assay. Multiple concentrations of the test substance over a range adequate to define the response, should be used. 

Mg in fertilizers is based on such proceedings thereof has been applied on multiple occasions. In milk fermentation, where the samples were dried, calcined in a furnace at 600 °C, the ash was dissolved in 0.03 M HCl, the solution was centrifuged and the supernatant was thus analyzed . The complexometric method for determination of Ca(II) and Mg(II) can be carried out in a single titration with EDTA in alkaline solution, using a Ca-ISE for potentiometric determination of two endpoints. This is accomplished on digitally plotting pCa values measured by the ISE as a function of the volume V of titrant added to the aliquot of analyte the first and second inflection points of the curve mark the Ca(II) and Mg(n) equivalences, respectively. ... 

Active Oxygen Determinations. A sample (ca. 2.5 grams) was removed from the solution, weighed to 0.05 gram, and diluted with about 20 ml. of pentane. Nitrogen was blown over the solution for about 1 minute. The solution was diluted with 100 ml. of isopropyl alcohol 2 ml. of glacial acetic acid and 1 ml. of saturated potassium iodide solution were then added in that order. Enough water (5-10 ml.) was added to dissolve the potassium iodide precipitate. This mixture was titrated with standard sodium thiosulfate (0.01N) to a colorless endpoint. If the mixture were not titrated immediately, a piece of dry ice was added, and the solution was stored in the dark. 

Assay Dissolve about 130 mg of sample, previously dried at 130° for 3 h and accurately weighed, in 3 mL of formic acid and 50 mL of glacial acetic acid, and titrate with 0.1 N perchloric acid, determining the endpoint potentiometrically. 

Assay Dissolve about 100 mg of sample, previously dried to constant weight over a suitable desiccant and accurately weighed, in 50 mL of water contained in a 250-mL glass-stoppered Erlenmeyer flask. Add 3 g of potassium iodide, followed by 3 mL of hydrochloric acid. Allow the mixture to stand for 5 min, add 100 mL of cold water, and titrate the liberated iodine with 0.1 N sodium thiosulfate, adding starch TS as the endpoint is approached. Perform a blank determination (see General Provisions), and make any necessary correction. Each milliliter of 0.1 N sodium thiosulfate consumed is equivalent to 2.783 mg of KBr03. 

Assay Dissolve about 250 mg of sample, dried at 105° for 2 h and accurately weighed, in 150 mL of water. Add 1 mL of nitric acid, and immediately titrate with 0.1 N silver nitrate, determining the endpoint potentiometrically, using silver-calomel electrodes and a salt bridge containing 4% agar in a saturated potassium nitrate solution. Perform a blank determination, and make any necessary correction (see General Provisions). Each milliliter of 0.1 N silver nitrate is equivalent to 7.455 mg of KCl. 

Emulsion Capacity and Stability. A 0.5 g sample of the freeze-dried protein fraction was redissolved in a minimum of 0.3 M citrate-phosphate buffer at pH 7.0 and mixed thoroughly with 50 ml of 1 M NaCl for 1 min in a Sorvall Omnimixer at 1000 rpm in a one pint Mason jar set in a water bath (20°C). Crisco oil (50 ml) was added to the jar and an emulsion formed by mixing at 500 rpm with simultaneous addition of oil at the rate of 1 ml/min until the emulsion broke. The endpoint was determined by monitoring electrical resistance with an ohmeter. As the emulsion broke a sharp increase (l KS2 to 35- 0 KSi) was noted. Emulsion capacity was expressed as the total volume of oil required to reach the inversion point per mg protein. This method is similar to that used by Carpenter and Saffle (8) for sausage emulsions. To establish emulsion stability the same procedure was used except that 100 ml of oil was added and a stable emulsion formed by blending at 1000 rpm for 1 min. A 100 ml aliquot was transferred to a graduate cylinder and allowed to stand at room temperature. Observations were made of the volume of the oil, emulsion and water phases at 30, 60, 90 and 180 min. 

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