Triglycerides, determination using

In all four formulations, however, there is also a pronounced dependence of the phase-separation process on the nature of the diamine and the epoxi-dized triglyceride rubber used for their preparation. As mentioned earlier, the DGEBA/DDS matrix is more polar than the DGEBA/DDM matrix because DDS is more polar than the DDM diamine. ESR is more polar than VR because the epoxy functionality of the initial ESO is twice as high as the epoxy functionality of VO. Both the particle-size distribution and the rubber content at which phase inversion occurs are determined by the miscibility of the two phases of the four types of formulations discussed. 

The glycerol, the source of carbon used in the fermentations, coneentration in the cell-free samples the cells were removed by centrifiigation at 6,000 rpm for 15 min—was evaluated by the enzymatic/colorimetric method for triglycerides determination (Enzymatic Triglyceride-Bioclin Quibasa Basic Chemistry, MG-Brazil). 

Blood samples were withdrawn in patients fasting for 12 hours. Standard methods were used for measurement or uric acid (9) total cholesterol was determined using an enzymatic method (Coles-Cinet Scalvo, Siena, Italy). Triglyceride levels were determined using an enzymatic method (Boehringer). HDL-cholesterol was determined using a Dextran Mg sulfate method (Chol-HDL Sclavo, Siena, Italy). 

The possibility of a liquid-liquid extraction of squalene from squalene + triglyceride mixtures using ethyl lactate was first reported by Hernandez et alP Taking into account the liquid-liquid phase transition measured (Figure 20.4.10), these authors determined the liquid-liquid equilibrium compositions of two selected systems, namely, a mixture with 90 wt% ethyl lactate and another one with 80 wt% ethyl lactate, at two selected temperatures, 298.15K and 313.15K. Both temperature-composition conditions were selected to promote the dissolution of squalene in the ethyl lactate rich phase (see Figure 20.4.10). 

Infrared spectra of fats and oils are similar regardless of their composition. The principal absorption seen is the carbonyl stretching peak which is virtually identical for all triglyceride oils. The most common appHcation of infrared spectroscopy is the determination of trans fatty acids occurring in a partially hydrogenated fat (58,59). Absorption at 965 - 975 cm is unique to the trans functionaHty. Near infrared spectroscopy has been utilized for simultaneous quantitation of fat, protein, and moisture in grain samples (60). The technique has also been reported to be useful for instmmental determination of iodine value (61). 

Potentiometry is another useful method for determining enzyme activity in cases where the reaction Hberates or consumes protons. This is the so-called pH-stat method. pH is kept constant by countertitration, and the amount of acid or base requited is measured. An example of the use of this method is the determination of Hpase activity. The enzyme hydroly2es triglycerides and the fatty acids formed are neutralized with NaOH. The rate of consumption of NaOH is a measure of the catalytic activity. 

This approach can be used only for fat-soluble compounds that follow the same lymphatic route to be transported to the liver as carotenoids. The bioavailability of the compound of interest is determined by monitoring the appearance of the compound and its newly formed intestinal metabolites in the postprandial chylomicron fraction of plasma [also called the density < 1.006 kg/L fraction or triglyceride-rich lipoprotein (TRL) fraction because it is generally a mixture of chylomicrons (CMs) and very low density lipoproteins (VLDLs)] as a function of the time after ingestion. 

H. Uzawa, Y. Nisbida, H. Ohrui, H. Meguro, A New Approach to Determine the Stereospecificity in Lipase Catalyzed Hydrolysis Using Circular Dichroism (CD) Lipases Produce Optically Active Diglycerides from Achiral Triglycerides , Biochem. Biophys. Res. Commun. 1990, 168, 506-511. 

Untreated silica column can be advantageously used for HPLC preseparation of PAHs from triglycerides. The capacity of a silica column to retain fat (for columns of the same particle size) depends on the column size, the mobile phase composition, as well as the type and by-products (free acids and polymerized material) of the fat injected [706,713]. Off-line HPLC-HPLC, employing silica column (250 X 4.6 mm i.d., 5 pm of particle size) for sample preparation before RP-HPLC and spec-trofluorometric detection, was successfully applied for PAH determination in edible oils [659,691] and fish [714]. After PAH elution, the silica column needs to be backflushed with dichloromethane to remove the fat. The entire sample preparation step can be automated by using a backflush valve and a programmable switching valve box [691]. 

The elution factors in normal-phase TLC and RP-HPLC, using a fixed set of chromatographic parameters, were determined for a series of saturated triacylglycerides with TCN from C30 to Ceo, serving as reference compounds and various oxidation derivatives of analogous unsaturated triglycerides, including hydroperoxides, peroxides, epoxides, core aldehydes and their DNP derivatives. From these measurements, a series of incremental... 

Extensive use has been made of NIRA in agriculture where it has been used to determine the protein, fibre, water and triglyceride contents of feedstuffs and the quality of crops. By training the computer to recognise the near-infrared (NIR) spectra of the major components making up a crop, the individual components can be monitored in the crop itself. The components that can be measured by NIRA often cannot be measured by the usual spectroscopic methods. The fundamental work done in the quality control of agricultural products can be readily extended to the quality control of pharmaceutical formulations. 

---