Porasil

MacMillan and Wright [133] identified and measured saturated and unsaturated 1,3- and saturated 1,4-sultones in anionic surfactants by a series of separation maneuvers. Ion exchange treatment separates sultones from the bulk of the ionic surfactant. TLC concentrates the sultones systems for HPLC analysis. They found that pentane-ether is preferable to the usual hexane-ether system and that the addition of a little methanol sharpens the separations. Finally, HPLC using a micro-Porasil column with 90 1 isooctane/ethanol provides quali-... 

Porasil C Carbowax 400 (7.86) Nonpolar 175 Low molecular weight alcohols. 

Porasil c n-Octanol Polar 175 Low molecular weight alcohols and hydrocarbons. 

Porasil c Phenyl isocyanate Polar 60 C,-C5 hydro- u tens and their isomers. 

Porasil F Carbowax 400 (1.41) Nonpolar 230 Higher molecular weight substances waxes, steroids, polynuclear aromatics. 

Figure 8.14 Senipreparative class separation of a diesel engine exhaust sample. Column 25 cm x 7.9 mm, lO micrometer Porasil. Solvent gradient hexane to 5% methylene chloride over 5 min., linear gradient to 100% methylene chloride over 25 min., isocratic for 10 min., linear gradient to 100% acetonitrile over 10 min., Isocratic for 5 min., step change to tetrahydrofuran for 10 min.,...

Silica is the most frequently used adsorbent and for use in HPLC it is sold under a variety of brand names such as LiChrosorb. LiChrospher, Nucleosil, Partisil, Porasil, Spherisorb, Spherosil, and Zorbax. For adsorption chromatography, silicas with a relatively large specific surface area (S0-4S0 m /g), a large pore volume (0.7-1.2 ml/g), ahd a moderate mean pore diameter (50-250 A) are used. 

Dilution in Hex, filtration, preparative HPLC p-Porasil (300mmx3.9mm,... 

Saponification, extraction with petroleum ether/Et20 (1/1), semipreparative HPLC (p-Porasil, 3000mmx3.9mm)... 

LiChrospher Zorbax SE Zorbax PSM M-Bondagel E P-Porasil 60 Glycophase-G MicroPak TSK Type SW... 

Porous silica (Porasil-C and D) water fractionation of dextrans 22,23... 

GC Durapak Carbowax 400 on Porasil F 100-120 mesh, 2) GC Durapak NOctane on Porasil C 100-120 mesh, 3) GC Durapak Phenylisocyanate on Porasil C 80-100 mesh, 4) GC Durapak OPN on Porasil C 80-100 mesh... 

Sedecamycin Swine EtOAc extn. Silica 13 Porasil, 10 m. n-Hexane/ UV 227 nm 12-44 ppb/ 153... 

Hydrocarbons containing two and three carbons are generally separated on packed columns. Chemically bonded materials such as n-octane or phenyl isocyanate on Porasil have proven to be good separator systems for these highly volatile nonmethane hydrocarbons. However, these systems require a separate analysis from that employed for the C4-C12 hydrocarbons (7). Recent developments include the use of capillary-type columns [e.g., Al203 porous layer open tubular (PLOT)] for separation of the lower molecular weight hydrocarbons (8). 

HPLC in the adsorption mode can be carried out with silica or alumina porous-layer-bead columns. Small glass beads are often used for the inert core. Some of the more widely used packings are /a Porasil (Waters Associates), BioSilA (Bio-Rad Laboratories), LiChrosorb Si-100 Partisil, Vydac, ALOX 60D (several suppliers), and Supelcosil (Supelco). 

The condensation reaction was carried out in a stirred 50 cm3 glass flask under a reflux condition. The reaction temperature was maintained by a heated silicon oil bath surrounding the reactor, and measured by a mercury thermometer immersed into the reaction mixture. After the reaction, the solid product and catalyst were separated from the reaction solution by filtration. The product was dissolved in ethyl acetate and separated from the catalyst particles by another filtration. The product was washed by water and then dried over MgS04. Analysis of the product was made with a 1IPLC (Waters 990) equipped with a —Porasil column. A 30% ethyl acetate in hexane was used as an eluent. The conversion of IICHO, the limiting reactant, was calculated from the isolated solid product. The selectivity was calculated by comparing the peak area of the main product with that for an authentic 4,4 —MDU sample. 

Betalains Materials Solvent A 18/82(v/v) CH3OH/0.05 M KH2PO, adjust to pH 2.75 with H3P04 Solvent B. CH3OH Sephadex G-25 (Amersham Pharmacia Biotech) water slurry, pH 2.0 adjust pH with HC1 Sample of beet juice or beet tissue extract (see Support Protocol), pH 2.0 adjust pH with HC1 1% acetic acid Four 7.88-mm x 61-cm Bondapak C,8/Porasil B columns connected in series 17.8/81.2/1.0 (v/v/v) CH3OH/0.05 M KH2P04/acetic acid 0.1% HC1... 

Column reversed-phase Bondapak C18/Porasil B (Water Associates)... 

Diuron Porasil, C8H18 MeOH PrOH Photoconductivity lOppb 130... 

Nonpolar nonvolatile NOC in foods and beverages 1. Extraction with CH3CN 2. Partitioning with isooctane None 300 X 4 mm /x-Porasil (Waters Associates) 1-5% acetone in 2,2,4-trimethylpentane TEA 50-90 45... 

There are only limited references in the literature regarding HPLC determination of nonpolar nonvolatile NOC in foods. In one of these studies, Fine et al. (45) used a /r-Porasil column and 1-5% acetone in iso-octane as the mobile phase for the HPLC-TEA determination of... 

Kaul and Lester (10) reported the preparation of six novel glycophosphoceramide fractions from the above crude concentrate from tobacco leaves. The crude concentrate was first resolved into two groups by column chromatography on diethyl aminoethyl-cellulose. The first group contained no acetyl residues, whereas the second group contained one N-acetyl per phosphorus. Three lipid fractions from each group were further resolved by chromatography on Porasil columns. The chemical composition and the percent of the total P in the crude concentrate of these lipid frac-... 

Normal-phase columns, either Water s jx Porasil or DuPont s Zorbax-sil , were used for the data of Sheridan s... 

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