Homogenization and Blending

NIR methods are not the only on-line applications for blend monitoring FT-Raman " and laser induced fluorescence (LIF) have been utilized. Refer to Chapter 11 for a comprehensive review of LIF. As stated herein, NIRS is well established as an effective and advantageous means to deem blend homogeneity and blending end point, however there are circumstances in which NIR is insufficient. For example, LIF can be more suitable for blends with low drug load. Lai and Cooney illustrated in a lab-scale experiment that LIE yielded a limit of detection below 0.02% w/w for a given API. ... 

A cheese-like spread, which is similar to processed cheese spread, is prepared by combining hydrolyzed Swiss-or Cheddar-whey protein and cultured cream. The whey protein is precipitated by heat and acid. The granular, chalky precipitate then acquires a smooth texture by enzymatic hydrolysis with Rhozyme P-11 at 39.5 to 40.5 °C for 30 min. The product is heated to 85 °C for 15 min to inactivate the enzymes then it is homogenized and blended with an equal quantity of 45° cream culture containing Lactobacillus casei (Webb and Whittier 1970). 

The main advantage of rotary kiln pyrolyzers is that the rotation of the pyrolyzing chamber guarantees the permanent turning and mixing of the waste plastic, so that the mixture is continuously homogenized and blended with inert pyrolysis gas. A rotary kiln pyrolyzer is shown in Figure 27.3. 

Extract recoveiy and treatment, including degassing, filtration, testing, d xydration, homogenization, and blending... 

The extraction of amino acids (Fig. 6,8) from medical plant extracts is again the use of cation exchange to remove organic bases (amino acids) from extracts of plants. Homogenize and blend the plant material with methanol. Filter the extract and evaporate to dryness. Reconstitute the sample with 10% methanol/water and filter. The extract is prepared for cation exchange. 

In 2008, Carretero et al. described a multi-class method for the analysis of 31 antibacterials (including f)-lactams, macrolides, lincosamides, quinolones, sulfonamides, tetracyclines, nitroimidazoles, and trimethoprim) in meat samples by PLE-LC-MS/MS. Meat samples were homogenized and blended with EDTA-washed sand, then extracted with water by applying 1500 psi (Ib/in. ), at 70°C. One extraction cycle was 10 min. A drawback of the method is the large volumes of extracts (40 ml) obtained, which required evaporation to concentrate the extract volume prior to final analysis. This evaporation step considerably increases the time required for sample preparation. The proposed method has been applied to the analysis of 152 samples of cattle and pig tissues, with the presence of quinolones, tetracyclines, and sulfonamides detected in 15% of the samples, although at concentrations below the MRLs. 

Sample pretreatment involves modification of the physical form of the sample in such a way that the dioxins can be extracted efficiently. Some environmental matrices such as fly ash require pretreatment involving acid attack, usually with HCl, to destroy the structure of the matrix and to allow better recovery of the dioxins. For certain samples, denatu-rants are added so as to destroy any protein-analyte interactions and disrupt micellular formation, both of which can decrease recoveries of dioxins. For example, formic acid has been used as a denaturant prior to extraction of dioxins in plasma or serum. Sodium or potassium oxalate (20 mg per g milk) is added to milk samples to disrupt fat globules. Depending on the type of sample, grinding, homogenization, and blending of various sample phases... 

MACROSCALE MIXING/PULP BLENDING OPERATIONS 20-5.1 Homogenization and Blending... 

The agitation of pulp stock for homogenization and blending is the most common mixing operation in pulp and paper manufacture. The blend chest (a well-mixed stirred vessel) illustrates the importance of macroscale mixing in pulp and paper processes. It is the heart of the stock preparation system and is used to mix two or more pulp streams, often with wet-end chemicals, dyes, fillers or additives, as well as providing a uniform feed of stock to the paper machine. Mixing chests... 

Ester plasticizers are used mainly in very polar elastomers, such as neoprene and nitrile mbber, to improve low or high temperature performance or impart particular oil or solvent resistance to a compound 5—40 parts are commonly used (see Plasticizers). Resins and tars are added to impart tack, soften the compound, improve flow, and in some cases improve filler wetting out, as is the case with organic resins in mineral-filled SBR. Resinous substances are also used as processing agents for homogenizing elastomer blends. 

Complexity within homopolymers as well as that of PBAs have made the task of analysis and characterization a difficult one. Basically, the task of analysis and characterization of PBAs is not different from that of simple low-molecular weight polymers, provided adequate solubility and sites are available for accepting artificial stimulation responses to those stimuli that may be used as functional tools for characterization. Properties of the blend mainly depend on the homogeneity of blends. The processes that are used for characterization of the PBAs are discussed in the following sections [128-131]. 

As mentioned above, neither of the reaction steps in the production of monoesters is particularly high in yield. The finished product therefore contains unreacted raw materials and/or intermediate products. The organic raw materials in themselves are mixtures of many substances. No natural raw material is homogeneous and any naturally based surfactant will be a blend. Fatty alcohol made from coconut oil, for example, is a product containing fatty alcohols from Cj0-Cj8 in varying amounts. Lauryl alcohol obtained from this raw material in its industrial form is a fatty alcohol mainly containing C12 fatty alcohol with, however, significant amounts of C10 and C14 fatty alcohols. 

Reactive compatibilization is also carried out by adding a monomer which in the presence of a catalyst can react with one or both phases providing a graft copolymer in situ that acts as a compatibilizer. Beaty and coworkers added methyl methacrylate and peroxide to waste plastics (containing polyethylene [PE], polypropylene [PP], PS, and poly(ethylene terephthalate) [PET]). The graft copolymer formed in situ homogenized the blend very effectively [19]. 

Residual pendimethalin in various crops was determined as follows." A 10-20-g amount of fruits or vegetables was extracted by blending twice with 200 mL of methanol. Grasses and mint were extracted with 200 mL of methanol-water (1 1, v/v). Nuts were extracted with 200 mL of n-hexane-2-propanol (3 1, v/v). For the residue analysis of the dinitroaniline herbicides butralin, dinitramine, ethalfluralin, pendimethalin, and trifluralin, a tomato sample (5 g) was extracted twice with 20 mL of methanol in a Sorvall homogenizer and filtered through filter paper. Benfluralin and trifluralin residues in the sample (10 g) were extracted with 100 mL of acetonitrile-water (99 1, v/v) in 250-mL screw-cap jars with Teflon liners rotated for 1 h on an end-over-end shaker (40 rpm). ... 

A 50-g homogenized plant sample is weighed into a centrifuge tube and blended at 7000 rpm with 100 mL of methanol-water (7 3, v/v) for 10 min. The resulting mixture is centrifuged at 5000 rpm for 5 min. The supernatant is collected in a 200-mL volumetric flask with suction. In the case of strawberry and peach, the supernatant is filtered through a glass filter (17G-3) previously packed with 10 g of Celite 545. The residue is re-extracted with 50 mL of the same aqueous methanol in the same manner as described above, and the supernatant is collected in a 200-mL volumetric flask. The volumetric flask is filled to the mark with the same aqueous methanol. 

Homogeneous and Heterogeneous Rubbery-Rubbery Diblock Copolymers and Polymer Blends A Unified View... 

Here the solid curve representing the boundary between homogeneous and heterogeneous blends is located at a position halfway between the two curves of Figure 1. The various data points shown... 

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