Preparative gel‐chromatographic separation of the hydrolysis products of polycarbonate on Sephadex LH‐20

Abstract

Preparative gel-chromatography Quantitative analysis of polycarbonates Hydrolysis of polycarbonates Polycarbonate samples (e.g. foils) can be readily and rapidly hydrolyzed by means of semi-concentrated ammonia under pressure (1 g polycarbonate in 40 ml semi-concentrated ammonia, 3 h at 13OOC). The hydrolysis products Bisphenol A and polyethylene glycol can be quantitatively separated from each other as well as from the urea formed (from the -0-CO-0-groups of the polycarbonate+ ammonia) as well as from any possible glycerol and determined very accurately via gravimetry. The hydrolysis product freed from excess ammonia is separated as mobile phase on Sephadex LH-20 via methanol (Figure 1) or acetone (Figure 2). In both cases, the separation time can be essentially reduced bya higherflow rate andlorshortercolumn. Forpracticalpurposes,the separation by means of acetone as eluent is most suitable even when larger amounts (20-30 weight-% relative to the polymer) of the pore-structure stabilizer glycerol are present in the foils (see Figure 2, peak 3). MW/mg 6000/25092/660 18/250 601216 228/841

Seven Novel Macrocyclic Polypeptides fromViolaarvensis

“…12 This has been utilized extensively for the separation of lowmolecular-weight substances. 11,13 Our results with the varv peptides indicate a similar behavior for polypeptides (Figure 1). Peptides containing one aromatic amino acid in addition to the conserved tryptophan (cf.…”

“…Reversed-phase adsorption is a known additive mechanism to size exclusion in chromatography on Sephadex LH-20, which has been proposed to be due to the interaction between the dextran gel matrix and aromatic solutes , Our results with the varv peptides indicate a similar behavior for polypeptides (Figure ). Peptides containing one aromatic amino acid in addition to the conserved tryptophan ( cf.…”

“…To increase the isolation yield of the peptides in this study, column chromatography on Sephadex LH-20 with 50% MeOH−0.1% TFA (v/v) in water was attempted. Contrary to true size-exclusion chromatography, in which an exclusion limit of approximately 4 kDa could be expected, the peptides eluted in the low-molecular-weight range of the column. Increasing the polarity of the eluent by adding water further increased the retention times of the peptides, indicating that the separation took place in a reversed-phase-like manner.…”

Analysis and Purification of Bioactive Natural Products: The AnaPurNa Study

“…In addition, the diversity of the purification methods was assessed and encoded into binary format as a byte integer, consisting of the following five bits: 0 = undefined or literature reference only; 2° = precipitation or crystallization; 2 1 = paper or thin-layer chromatography (TLC), including centrifugal TLC; 2 2 = column liquid chromatography (LC), vacuum LC, and low-pressure LC, and the value 2 1 was added to encode repetition in the entire scheme; 2 3 = medium-pressure and high-pressure LC (MLPC, HPLC), and also the value 2 1 was added to encode repetition in the entire scheme; 2 4 = countercurrent chromatography. The reported LC techniques applied numerous different solid-phase packings, which were not individually differentiated in the survey and included primarily the following: normal- and reversed-phase (RP-8/18; cyano) silica gel; Sephadex LH-20 (see ref (10) for a comprehensive review); styrene resins (see ref (11) for theory and applications).…”