Analysis glycerol

Animal fats and vegetable oils are triacylglycerols, or triesters, formed from the reaction of glycerol (1,2, 3-propanetriol) with three long-chain fatty acids. One of the methods used to characterize a fat or an oil is a determination of its saponification number. When treated with boiling aqueous KOH, an ester is saponified into the parent alcohol and fatty acids (as carboxylate ions). The saponification number is the number of milligrams of KOH required to saponify 1.000 g of the fat or oil. In a typical analysis, a 2.085-g sample of butter is added to 25.00 ml of 0.5131 M KOH. After saponification is complete, the excess KOH is back titrated with 10.26 ml of0.5000 M HCl. What is the saponification number for this sample of butter ... 

The methods of analysis of the American Oil Chemists Society (AOCS) are the principal procedures followed in the United States and Canada and are official in commercial transactions. When the material is for human consumption or dmg use, it must meet the specifications of the USP (12). Commercial distilled grades of glycerol do not requite purification before analysis by the usual methods. The deterrnination of glycerol content by the periodate method (13), which replaced the acetin and dichromate methods previously used, is more accurate and more specific as well as simpler and more rapid. 

Mass spectral analysis of quaternary ammonium compounds can be achieved by fast-atom bombardment (fab) ms (189,190). This technique rehes on bombarding a solution of the molecule, usually in glycerol [56-81-5] or y -nitroben2yl alcohol [619-25-0], with argon and detecting the parent cation plus a proton (MH ). A more recent technique has been reported (191), in which information on the stmcture of the quaternary compounds is obtained indirectly through cluster-ion formation detected via Hquid secondary ion mass spectrometry (Isims) experiments. 

The thin-layer technique (CA 60, 6691) utilizes aliquots of proplnt ether extract (I) and the ether soln (II) of a known mixt. II consists of nitrates of glycerol and glycol, di-Bu or di-Et phthalates, Et or Me centralites, DNT, and diphenylamine. The chromatoplates are made of 85 15 silica gel and plaster of Paris. These plates, containing spots of I and 11, are developed with 1 1 C6H6-petroleum ether, then sprayed with specific detectors by color. The method is much quicker and easier than chemical analysis and simpler than infrared spectroscopy and column chromatography... 

Sundback CA, Shyu JY, Wang YD, Faquin WC, Danger RS, Vacanti JP, and Hadlock TA. Biocompatibility analysis of poly(glycerol sebacate) as a nerve guide material. Biomaterials, 2005, 26, 5454-5464. 

Dynamic light-scattering experiments or the analysis of some physicochemical properties have shown that finite amounts of formamide, A-methylformamide, AA-dimethyl-formamide, ethylene glycol, glycerol, acetonitrile, methanol, and 1,2 propanediol can be entrapped within the micellar core of AOT-reversed micelles [33-36], The encapsulation of formamide and A-methylformamide nanoclusters in AOT-reversed micelles involves a significant breakage of the H-bond network characterizing their structure in the pure state. Moreover, from solvation dynamics measurements it was deduced that the intramicellar formamide is nearly completely immobilized [34,35],... 

In the author s laboratory, it has never been found necessary to resort to matrices other than glycerol or 1-thioglycerol for the analysis of saccharides and glycoconjugates. Nevertheless, alternative matrices are often equally effective, and, in some laboratories, they are preferred. The most widely used include tetraethyleneglycol (4) and its higher-molecular-weight relatives, the poly(ethyleneglycol)s, and such basic matrices as N,N -bis(2-aminoethyl)ethylenediamine ( triethylenetetramine, 5), 2,2 -... 

The simultaneous analysis of orthophosphate, glycerol phosphates, and inositol phosphates has been achieved by spectrophotometric analysis of the molybdovanadate complexes. Also, a sensitive and selective chemiluminescent molecular emission method for the estimation of phosphorus and sulphur is described, which is based on passing solutions into a cool, reducing, nitrogen-hydrogen diffusion flame. For organic compounds it was usually necessary to prepare test solutions by an oxygen-flask combustion technique. 

In the wine industry, FTIR has become a useful technique for rapid analysis of industrial-grade glycerol adulteration, polymeric mannose, organic acids, and varietal authenticity. Urbano Cuadrado et al. (2005) studied the applicability of spectroscopic techniques in the near- and mid-infrared frequencies to determine multiple wine parameters alcoholic degree, volumic mass, total acidity, total polyphenol index, glycerol, and total sulfur dioxide in a much more efficient approach than standard and reference methods in terms of time, reagent, and operation errors. 

Further indications for an additional subunit were provided by a crosslinking analysis of C Eg solubilized H,K-ATPase, which exhibited ATPase and phosphatase activities, and ligand affinities comparable to the native enzyme [70]. Glutar-aldehyde treatment of soluble protein fractions resolved on a linear glycerol gradient revealed no active fraction enriched in monomeric (A/p = 94 kDa) H,K-ATPase. Instead, K -ATPase activity was only obtained in fractions enriched in particles of Mr = 175 kDa. This size also suggested that the functional H,K-ATPase unit is a heterodimer of a catalytic subunit and an additional subunit, since the apparent molecular mass of 175 kDa is probably too small to be a homodimer of the catalytic subunit. 

Obviously, use of such databases often fails in case of interaction between additives. As an example we mention additive/antistat interaction in PP, as observed by Dieckmann et al. [166], In this case analysis and performance data demonstrate chemical interaction between glycerol esters and acid neutralisers. This phenomenon is pronounced when the additive is a strong base, like synthetic hydrotalcite, or a metal carboxylate. Similar problems may arise after ageing of a polymer. A common request in a technical support analytical laboratory is to analyse the additives in a sample that has prematurely failed in an exposure test, when at best an unexposed control sample is available. Under some circumstances, heat or light exposure may have transformed the additive into other products. Reaction product identification then usually requires a general library of their spectroscopic or mass spectrometric profiles. For example, Bell et al. [167] have focused attention on the degradation of light stabilisers and antioxidants... 

FAB has been used to analyse additives in (un) vulcanised elastomer systems [92,94] and FAB matrices have been developed which permit the direct analysis of mixtures of elastomer additives without chromatographic separation. The T-156 triblend vulcanised elastomer additives poly-TMDQ (AO), CTP (retarder), HPPD (antiozonant), and TMTD, OBTS, MBT and A,lV-diisopropyl-2-benzothiazylsulfenamide (accelerators) were studied in three matrix solutions (glycerol, oleic acid, and NPOE) [94]. The thiuram class of accelerators were least successful. Mixture analysis of complex rubber vulcanisates without chromatographic separation was demonstrated. The differentiation of matrix ions from sample ions was enhanced by use of high-resolution acquisition. 

Whereas the use of conventional fast atom bombardment (FAB) in the analysis of polymer/additive extracts has been reported (see Section 6.2.4), the need for a glycerol (or other polar) matrix might render FAB-MS analysis of a dissolved polymer/additive system rather unattractive (high chemical background, high level of matrix-, solvent- and polymer-related ions, complicated spectra). Yet, in selected cases the method has proved quite successful. Lay and Miller [53] have developed an alternative method to the use of sample extraction, cleanup, followed by GC in the quantitative analysis of PVC/DEHP with plasticiser levels as typically found in consumer products (ca. 30 %). The method relied on addition of the internal standard didecylphthalate (DDP) to a THF solution of the PVC sample with FAB-MS quantitation based on the relative signal levels of the [MH]+ ions of DEHP and DDP obtained from full-scan spectra, and on the use of a calibration curve (intensity ratio m/z 391/447 vs. mg DEHP/mg DDP). No FAB-matrix was added. No ions associated with the bulk of the PVC polymer were observed. It was... 

Figure 5. Analysis (21) according to Eq. 7 of gel-point data (22) from reactions of diacid chlorides (adipoyl and sebacoyl chlorides) and POP triols (LHT240, LHT112 (oxypropylated 1,2,6-hexane triols), and LG56 (oxypropylated glycerol)) in bulk and in diglyme solution at 60°C, with cext = cao...

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