(Kal. citr.) Sodium citrate Natrii citras (Natr. citr.) 2. Herb-derived substances Any plant, whether in whole, broken or cut to pieces as well as any unprocessed, fresh or dried plant part is considered a herb-derived substance. Untreated vegetal secretions are also considered substances of plant origin. Every substance, whose active ingredients are one or more herbal drugs or drug preparations and nothing else or the combination of such herbal drug(s) and drug preparation(s) are considered herbal medicines. Table herbs Ph. Eur.7. English name Ph.Eur.7. Latin name and abbrev. Wormwood Absinthii herba (Absinth. herb.) Yarrow Millefolii herba (Millefol. herb.) Agar Agar Agrimony Agrimoniae herba (Agrimon. herb.) Aloes, cape Aloe capensis (Aloe cap.) Marshmallow leaf Althaeae folium (Alth. fol.) Marshmallow root Althaeae (Alth. rad.) Maize starch Maydis amylum (Mayd. amyl.) Potato starch Solani amylum (Solan. amyl.) Wheat starch Tritici amylum (Trit. amyl.)
ionic nh number of hydrophilic groups in molecule Hh value of hydrophilic groups in molecule nl number of lipophilic groups in molecule Hl value of lipophilic groups in molecule In the case of fatty acid esters of polyvalent alcohols, HLB value can be determined by the following correlation: (15.) S saponification number Aacid number HLB can be also calculated with ethoxy number and alcohol groups: (16.) E number of ethoxy groups Pnumber of alcohol groups in polyvalent alcohol or with hydration heat: (17.) Q hydration heat The surface active materials can have natural or synthetic origin. According to their structure, ionic and can be distinguished. Natural surface active materials may be: 1) hydrocarbon derivatives (e.g. acacia, tragacanth, agar-agar, pectin) 2) protein types (such as gelatin, casein), 3) high molecular weight alcohols (e.g. stearyl alcohol, cetyl alcohol, cholesterol), 4) other (pl.: lecithin). 5) The ionic surface active materials can be cation or anion type. 6) Dispersion process of type surface active materials results in negative charged ions in water. Soaps (e.g. sodium palmitate, sodium stearate, sodium oleate), alkyl sulfates, alkyl phosphates are categorized to this group. Sodium lauryl sulfate has especially very great moistening and strong solubilizing and cleaning effect, with high HLB. Fig. of anion type surface active substances (Sodium lauryl sulfate)
The spatial description of the regular, structured layout of crystals is defined using a mathematical model, a space-lattice. According to this, the space-lattice is a regular, infinite array of zero-dimensional points (lattice points) in space. Definition of crystal: 1) state material with space-lattice structure, 2) anisotropic in certain regards, 3) homogenous discontinuity. Anisotropic, for crystals always exhibit directional properties. Discontinuity, for there is great distance between crystal-forming atoms, therefore space filling is discontinuous, imperfect. Depending on their habit, crystals can be: 1) isometric, 2) needlelike, 3) columnar, 4) tabular or 5) lamellar. Fig. habits Crystal is the shape, the external appearance of crystals. In pharmaceutical technology its significance is in its effect on pressability, facility and fluidity, while in terms of biopharmacy it can influence biological applicability. Euler established a formula about the correlation between the numbers of a crystal’s faces, vertices and edges: f + v = e + 2 (1.) f number of v number of vertices e number of The concept of unit cell has been introduced by Bravais. Unit cells possess the attributes of the complete lattice structure and its symmetric relationships, thus it is the smallest unit of the crystal lattice. In theory, the whole crystal could be constructed by translating the unit cell in parallel with the three directions of space. Fig. cell If a lattice node is selected as starting the other lattice nodes can be accessed by translation: (2.) translation translations connecting the starting point with adjoining lattice nodes
Surface filtration can be performed with perforated plate, sieve plate, wire mesh, filter cloth, felt or filter paper. The primary function of the filter plate is therefore not full filtering, but enabling the formation of a filter cake by providing a suitable sustaining surface for the depositing mass of particles and withstanding the strain of vacuum or pressure. In case of filtration (e.g. activated carbon filtration) the particles finer than the pore size of the filter medium enter the pores and channels of the grainy or fibrous filter medium and deposit there. Particles accumulate in the cavities of pores and capillaries due to direction breaksand changes in channel cross section, depositing due to inertial and surface forces. The cake forming on the surface is insignificant. Extremely fine particles are adsorptively bound by surface and capillary forces. In the course of filtration the permeable cross section and porosity of pores decreases and the resistance of the filter medium increases. Fig. filtration The above mechanisms are often intermingled in real-life filtration processes, with the filter initially retaining only larger particles, acting as a surface filter, producing a cloudy filtrate. Later, with the formation and buildup of the filter cake the depth filtering mechanism prevails and subsequently the filtrate gradually clears up. The filter’s performance is described by the filtration rate (the amount of filtrate flowing through in a unit of time, V/t). Filtration rate in correlation with unit filter surface (A) is: (1.) The Hagen – Poiseuille law is applicable in case of laminar, frictional and temporally constant flow. According to this, filtration can be considered a flow flowing through parallel capillaries and average rate is one half of maximum rate: (2.) r radius of capillary, h viscosity of liquid, h length of capillary. Darcy studied the flow of liquids through granular media at constant pressure and established that filtration rate is : (3.) V volume of filtrate, t duration of filtration, B permeability constant of the filter bed, A filter surface,
Δpldrop of pressure on the filter bed, η dynamic viscosity of filtrate, L width of filter bed. Taking the resistance of the cake into consideration: (4.) Rm resistance of filter medium, α specific cake-resistance, c concentration of the substance to be filtered The Carman equation is the base equation of filtration: (5.) V volume of filtrate, c mass of particles aggregating from a unit of filtrate, Rm resistance of filter medium, A filter surface. Specific cake resistance (α) is: (6.) ε porosity, ρs density of solid particles, af specific surface of particles. The Kozeny-Carman relation applies to laminar flow passing through agglomerated particles. According to the the permeability constant is: (7.) (8.) ε porosity, η viscosity, k Kozeny-Carman constant, li width of sludge cake,