4-methyl-2-pentanone conductivity

Recovery experiments were conducted with the following standards, which were used as received without further purification 5-chlorouracil (Calbiochem), furfural (Aldrich), crotonaldehyde (Aldrich), caffeine (Aldrich), isophorone (Aldrich), 2,4-dichlorophenol (Aldrich), anthraquinone (Aldrich), biphenyl (Ultra Scientific), 2,4 -dichlorobiphenyl (Ultra Scientific), 2,6-bis(l,l-dimethylethyl)-4-methylphenol (Aldrich), 2,2, 5,5 -tetrachlorobiphenyl (Ultra Scientific), benzo[e]pyrene (Aldrich), bis(2-ethylhexyl) phthalate (Scientific Polymer Products), 4-methyl-2-pentanone (Aldrich), quinoline (Kodak), 1-chloro-dodecane (Eastman), stearic acid (Kodak), quinaldic acid (Aldrich), trimesic acid (Aldrich), glucose (Aldrich), glycine (Aldrich), and chloroform (Burdick and Jackson). 

Marsili compared SPME and dynamic headspace (DH) GC/MS techniques for the analysis of light-induced lipid oxidation products in milk (4). In the SPME method, 3 g of milk (2% milkfat) and 4-methyl-2-pentanone internal standard (10 jL of a 20 ppm solution in methanol) were placed in a 9-mL vial and capped. A 75- j,m Carboxen-1006/PDMS fiber was inserted into the headspace above the milk sample. Hie Carboxen/PDMS fiber has a combination of micro-, meso-, and macro-pores ranging from 6 to 50A. The volatile flavor compounds that are the best indicators of light-induced oxidation in milk are pentanal, hexanal, and dimethyl disulfide. The Carboxen/PDMS fiber was selected for this study because it is well suited for the analysis of low-molecular-weight volatiles. Adsorption of volatiles from the milk onto the SPME fiber was conducted at 45 C for 15 min with stirring. The sealed vial was allowed to equilibrate for 2 min at 45 C before the SPME fiber was inserted. 

The atmospheric lifetime of 2,4-dimethyl-2-pentanol with respect to reaction with OH radicals is estimated to be 10 h using [OH] = 2.5 x 10 molecule cm and the rate coefficient presented in this section. The product study conducted by Atkinson and Aschmann (1995) using GC-FK) and GC-MS showed that the reaction of OH with 2,4-dimethyl-2-pentanol gives the following products (molar yields) Acetone (92 15%), 2-methylpropanal (21 22%), 4-methyl-2-pentanone (5 1%), and 4-hydroxy-4-methyl-2-pentanone (12 2%). In addition, the yield of a tertiary nitrate was estimated to be 4 1%. 

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