Transferable atom equivalent method

Breneman, C. M., Thompson, T. R., Rhem, M., and Dung, M. (1995) Electron density modeling of large systems using the transferable atom equivalent method. Comp. Chem. 19, 161-179. 

Breneman, C. M. and Rhem, M. (1997) QSPR Analysis of HPLC column capacity factors for a set of high-energy materials using electronic van der Waals surface property descriptors computed by transferable atom equivalent method. J. Comput. Chem. 18, 182-197. 

Pullman and Pullman 1981a Scrocco andTomasi 1973 Tomasi 1981). Breneman, quite recently, has developed a method in which V(r) is computed from densities obtained through transferable atom equivalents (Breneman 1996) the resulting electrostatic potentials Eire of ab initio quality. 

Whitehead, C. E., Breneman, C. M., Sukumar, N., and Ryan, M. D. (2003) Transferable atom equivalent multi-centered expansion method. J. Comput. Chem. 24, 512-529. 

Whitehead C, Breneman C, Sukumar N, Ryan M. Transferable atom equivalent multicentered multipole expansion method. J Comput Chem 2003 24 512-29. 

Another assay that is very similar to the ABTS assay is the AGV-dimethyl-p-phenylenediamine (DMPD assay). In the presence of a suitable oxidant solution at an acidic pH, DMPD is converted to a stable and colored DMPD radical cation (DMPD +). Antioxidants capable of transferring a hydrogen atom to the radical cause the decol-orization of the solution, which is spectrophotometrically measured at 505 nm. The reaction is stable, and the endpoint is taken to be the measure of antioxidant efficiency. Antioxidant ability is expressed as Trolox equivalents using a calibration curve plotted with different amounts of Trolox (Fogliano and others 1999). This method is used to measure hydrophilic compounds. The presence of organic acids, especially citric acid, in some extracts may interfere with the DMPD assay, and so this assay should be used with caution in those extracts rich in organic acids (Gil and others 2000). 

Free Fatty Acids (as stearic acid) Transfer 2 g of sample, accurately weighed, into a dry, 125-mL Erlenmeyer flask containing 50 mL of acetone, fit an air-cooled reflux condenser onto the neck of the flask, boil the mixture on a steam bath for 10 min, and cool. Filter through two layers of Whatman No. 42, or equivalent, filter paper, and wash the flask, residue, and filter with 50 mL of acetone. Add phenolphthalein TS and 5 mL of water to the filtrate, and titrate with 0.1 A sodium hydroxide. Perform a blank determination (see General Provisions) using 100 mL of acetone and 5 mL of water, and make any necessary correction. Each milliliter of 0.1 A sodium hydroxide is equivalent to 28.45 mg of stearic acid (CigH gOi). Lead Determine as directed in the Flame Atomic Absorption Spectrophotometric Method under Lead Limit Test, Appendix NIB, using a 10-g sample. 

Aminopropanol Transfer about 5 g of sample, accurately weighed, into a 50-mL flask, and dissolve in 10 mL of water. Add bromothymol blue TS, and titrate with 0.1 A sulfuric acid from a microburet to a yellow endpoint. Each milliliter of 0.1A sulfuric acid is equivalent to 7.5 mg of aminopropanol. Lead Determine as directed in the Flame Atomic Absorption Spectrophotometric Method under Lead Limit Test, Appendix IIIB, using a 5-g sample. 

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