Gelatin, solution preparation

Hot, demineralized water is used in the preparation of the dipping solution. Initially, a 30 40% w/w solution of gelatin is prepared in large stainless steel tanks. Vacuum may be applied to assist in the removal of entrapped air from this viscous preparation. Portions of this stock solution are removed and mixed with any other ingredients, as required, to prepare the dipping solution. At this point, the viscosity of the dipping solution is measured and adjusted. The viscosity of this solution is critical to the control of the thickness of the capsule walls. 

FIGURE 8.2 Response surface diagram for the mean particle size of gelatin microparticles prepared with variation in concentration and volume of type B, Bloom 225, gelatin solutions. (From Oner, L. and Groves, M.J. (1993a). Pharm. Res., 10(9), 1385-1388. With pemission.)... 

The emulsions used in this work were composed of the suspension of AgBr grains in aqueous gelatin solution, and were prepared by the controlled double-jet precipitation method. The edge lengths... 

With freshly prepared gelatine solution tannic acid, but not gallic acid, gives a precipitate with potassium cyanide solution, tannic acid remains unaltered whereas gallic acid gives a red coloration. 

Measurements are usually made on dry preparations in order to avoid the swelling of the fibres in a liquid. In this case the microscope slide is conveniently smeared with a dilute hot gelatine solution, on which the fibres are placed immediately. 

B. Add 1 mL of 2 A sulfuric acid to 5 mL of the solution prepared for Identification Test A. A heavy gelatinous precipitate forms. 

Experimental. The gelatin solutions were prepared as 0.75-1.0 wt % in distilled water. The samples were made from the dry stock daily by heating the gelatin-water mixture to 40 °C for complete dissolution and then cooling to 24 zh 1°C for the lEP determinations. 

Sodium lauryl sulphate is used in the production of hard gelatin capsules where it is added to the gelatin solution during the preparation stage. The stainless steel molds are lubricated prior to dipping into the gelatin solution and sodium lauryl sulphate is added to reduce the surface tension of the mix and cause the mold pins to wet more uniformly.f ... 

The GOD membranes were prepared as follows a 5% gelatin solution was incubated for 1 h at room temperature and then stirred for 1 h at 40°C. 1 mg GOD (P. notatum, 46 U/mg) was mixed with 40 pi of the solution and the resulting solution was cast on 1 cm2 of a planar support. After drying for 6 h the membrane was removed and stored under dry conditions at 4°C until use. 

Photon Correlation Spectroscopy Studies. In order to investigate possible aggregate formation between the gelatins at 40°C photon correlation spectroscopy was used. The following pairs of Type A and Type B gelatin solutions (0.5% w/v) were prepared and studied by PCS both individually and as mixtures and the values obtained for the average particle diameter and the polydispersity were compared ... 

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