Cellulose commercial samples

Figures 10 and 11 show how porcine trypsinogen can be prepared in high yield by chromatography on CM-cellulose. The amino acid composition of this protein is given in Table III, with two sets of values for the bovine precursor. Analytical results have also been obtained with a commercial sample of bovine trypsin (123).

If ferrous ions are present during assays of DNA and RNA polymerases in which radioactive newly synthesized polynucleotides are precipitated on to filter paper discs in trichloroacetic acid, spuriously high results are obtained, apparently due to acid-insoluble complexes of Fe with substrate nucleotides precipitating on the paper. Clearly ferrous ions should be avoided in assays of this type. The complex Al. ATP is a potent inhibitor of hexokinase, and neutron activation analysis of many commercial samples of ATP has shown that Al is ubiquitous, and the most common metal contaminant It is best removed by passing the ATP preparation over a cellulose polyphosphate column at pH 5. Chelates of ATP with divalent metal ions have been separated from non-chelated ATP using reverse-phase h.p.l.c. ... 

Poly-Et ether Ethyl cellulose. Ethocel. Ethylcellulose, INN [9004-57-3] Prepared by etherification of alkaline cellulose with ethyl chloride. Commercial samples have DS values of 2.2 - 2.7. Annual worldwide production ca. 5000t. Used in hot-melt adhesives and electrically insulating layers and coatings. Binder and coating for pharmaceutical tablets. Binder and coating for pharmaceutical tablets. 

Prepared by etherification of alkaline cellulose with ethylene oxide. Commercial samples have MS values of 1.8 - 3.5. Worldwide production in 1987 38,500 t. Thickener, binder, stabiliser and suspending agent with widespread uses in the paint, oil and polymer industries. 

Hydroxyethyl methyl cellulose. HEMC [9032-42-2] Prepared by etherification of alkaline cellulose with chloromethane and oxirane. Commercial samples have methyl DS values of 1.3 - 2.2 and hydroxyethyl MS values of 0.06 - 0.5. Thickening and binding agent with widespread industrial uses in adhesives, building products, films, wetting agents. Pharmaceutical adjuvant. Better water solubility and electrolyte tolerance than methyl cellulose. Thermally gellable in hot water. Soly in org. soivs. varies with DS value. 

PLA Poly(lactic acid) commercial sample from Mitsui Chemicals Composting (ISO 14855-1, ISO 14855-2, enzymatic degradation) CO2 evolution measurement based on titration and gravimetric methods Biodegradation of PLA powder was 91% for 31 days (ISO 14855-1 method) and 80% for 50 days at 58°C (ISO 14855-2 method) Cellulose powder was used as reference material PLA in the form of powders of different size was used [17]... 

Water-soluble cellulose derivatives of very different hydrophilicity and viscosity as well as swelling and gelation properties are commercially available. Extensive work has been carried out on the behavior of cellulose derivatives in aqueous solutions, but fundamental data are missing and available information Is usually difficult to Interpret -as compared with that concerning synthetic polymers [56,57] - by the wide molecular weight distribution of commercial samples and by uncertainties in the manner in which the substituent groups have been introduced. 

The purpose of this study is only intended to illustrate and evaluate the decision tree approach for CSP prediction using as attributes the 166 molecular keys publicly available in ISIS. This assay was carried out a CHIRBASE file of 3000 molecular structures corresponding to a list of samples resolved with an a value superior to 1.8. For each solute, we have picked in CHIRBASE the traded CSP providing the highest enantioselectivity. This procedure leads to a total selection of 18 CSPs commercially available under the following names Chiralpak AD [28], Chiral-AGP [40], Chiralpak AS [28], Resolvosil BSA-7 [41], Chiral-CBH [40], CTA-I (microcrystalline cellulose triacetate) [42], Chirobiotic T [43], Crownpak CR(-i-) [28], Cyclobond I [43], DNB-Leucine covalent [29], DNB-Phenylglycine covalent [29], Chiralcel OB [28], Chiralcel OD [28], Chiralcel OJ [28], Chiralpak OT(-i-) [28], Ultron-ES-OVM [44], Whelk-0 1 [29], (/ ,/ )-(3-Gem 1 [29]. 

Fig. 17.9. Purity comparison (SDS-PAGE) of the conventional purification process and integrated cell disrupt tion/fluidised bed adsorption.The numbers given in the flow sheet indicate the origin of samples and correspond to their respective lane numbers. Lanes M, low molecular weight markers 1, Erwinia disruptate, 15% biomass ww/v 2, eluate CM HyperD LS, fluidised bed 3, desalted eluate (after dia/ultrafiltration, 30 K MWCO membrane) 4, flow-through, DEAE fixed bed 5, elution, DEAE fixed bed 6, eluate CM HyperD LS 7, CM cellulose eluate 8, CM cellulose eluate, final 9, final commercial product.

The Fourier Trairsform Infrared (FTIR) spectrum obtained from non-adapted tomato cell walls is very similar to that from the onion parenchyma cell wall (both contain cellulose, xyloglucan and pectin) although there is more protein in the tomato walls (amide stretches at 1550 and 1650 cm-i) (Fig 4). In DCB-adapted tomato cell walls, the spectrum more closely resembles that of either purified pectins or of a commercial polygalacturonic acid sample from Sigma with peaks in common at 1140, 1095, 1070, 1015 and 950 cm-t in the carbohydrate region of the spectrum as well as the free acid stretches at 1600 and 1414 cm-i and an ester peak at 1725 cm-k An ester band at 1740 cm-i is evident in both onion parenchyma and non-adapted tomato cell wall samples. It is possible that this shift in the ester peak simply reflects the different local molecular environment of this bond, but it is also possible that a different ester is made in the DCB-adapted cell walls, as phenolic esters absorb around 1720 cm-i whilst carboxylic esters absorb at 1740 cm-k The... 

The membrane is critically important in osomometry. Selection of a membrane involves reconciliation of high permeability toward the solvent with virtual impermeability to the smallest polymer molecules present in the sample. Membranes of cellulose are most widely used. Commercially Regenerated cellulose film is a common source. The undried gel cellophane film is often preferred, but the dry film may be swollen in water (or in aqueous solutions of caustic or zinc chloride ) to satisfactory porosity. Useful cellulose membranes may also be prepared by denitration of nitrocellulose films/ and special advantages have been claimed for bacterial cellulose films. The water in the swollen membrane in any case may be replaced by a succession of miscible organic solvents ending with the one in which osmotic measurements are to be made. Membranes of varying porosity may be... 

Plates with 0.5- to 2-mm layer thickness are normally nsed for increased loading capacity. Layers can be self-made in the laboratory, or commercially precoated preparative plates are available with silica gel, alumina, cellulose, C-2 or C-18 bonded siliea gel, and other sorbents. Resolution is lower than on thinner analytical layers having a smaller average partiele size and particle size range. Precoated plates with a preadsorbent or eoneentrating zone faeilitate application of sample bands. 

The TLC process is an off-line process. A number of samples are chromatographed simultaneously, side-by-side. HPTLC is fast (5 min), allows simultaneous separation and can be carried out with the same carrier materials as HPLC. Silica gel and chemically bonded silica gel sorbents are used predominantly in HPTLC other stationary phases are cellulose-based [393]. Separation mechanisms are either NPC (normal-phase chromatography), RPC (reversed-phase chromatography) or IEC (ion-exchange chromatography). RPC on hydrophobic layers is not as widely used in TLC as it is in column chromatography. The resolution capabilities of TLC using silica gel absorbent as compared to C S reversed-phase absorbent have been compared for 18 commercially available plasticisers, and 52 amine and 36 phenolic AOs [394]. 

Urea in kidney dialysate can be determined by immobilizing urease (via silylation or with glutaraldehyde as binder) on commercially available acid-base cellulose pads the process has to be modified slightly in order not to alter the dye contained in the pads [57]. The stopped-flow technique assures the required sensitivity for the enzymatic reaction, which takes 30-60 s. Synchronization of the peristaltic pumps PI and P2 in the valveless impulse-response flow injection manifold depicted in Fig. 5.19.B by means of a timer enables kinetic measurements [62]. Following a comprehensive study of the effect of hydrodynamic and (bio)chemical variables, the sensor was optimized for monitoring urea in real biological samples. A similar system was used for the determination of penicillin by penicillinase-catalysed hydrolysis. The enzyme was immobilized on acid-base cellulose strips via bovine serum albumin similarly as in enzyme electrodes [63], even though the above-described procedure would have been equally effective. 

Three filtering media commercially available from Millipore Corporation were evaluated for the collection of airborne particulates of the organoarsenical compounds. These were (l) cellulose ester membranes (2) Fluoropore and (3) Mitex. The cellulose ester membrane filters (0.8 ym pore size) are the standard Millipore filters used for aerosol sampling and consist of a mixture of cellulose nitrate and cellulose acetate. The Fluoropore filters are made of Teflon (PTFE) and are bonded to a polyethylene net. Fluoropore filters with a pore size of 1.0 ym were selected for this study. 

This method uses the same materials and apparatus as described above (see Basic Protocol 1). In addition a standard material, such as microcrystalline cellulose (MCC), starch, filter paper, glycerol, or polyethylene glycol is needed for this protocol. The standard material is selected based on the commercial availability of a material with high purity and consistency over time, moreover, the standard must be stable during reuse of the material. Thus, MCC is recommended (Spiess and Wolf, 1987). Once the standard is chosen, it is used as a replacement for the sample in the procedure described above (see Basic Protocol 1), while the sample replaces the salt. 

Our experimental work started from the following original cellulose samples (a) acetate-grade, bleached cotton linters, DP 1800 (b) hot, refined, spruce, sulphite-dissolving pulp, machine dried, ca. 93% a-cellulose, DP — 750 (c) never-dried, normal, rayon-grade, beech sulphite pulp, ca. 90% a-cellulose, DP = 825 (d) commercial cellulose powders obtained by hydrolytic degradation and/or mechanical disintegration of cotton linters or spruce sulphite pulp. 

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