Sodium acetate, chromatographic separation, analysis

Bertoldi and colleagues (2004) performed analysis of BAs in grape juice by automatic pre-column derivatization with OPA solution (45 mg OPA, 200 pX 2-mercaptoethanol, 1 mL methanol, sodium tetraborate decahydrate 0.1 M pH 10.5 buffer solution added up to final volume of 10 mL). Chromatographic separation of derivatives (see Figure 4.13) was achieved on a C18 (4.6 x 150mm, 5 pan) column kept at 40 °C at flow rate lmL/min. Eluent A was 0.05 M sodium acetate buffer/tetrahydrofuran 96 4 (v/v) and eluent B was methanol. The gradient program is reported in Table 4.1. 

A significantly better separation between the two disaccharides is obtained with a more complex NaOH gradient. Instead of zinc acetate, small amounts of sodium acetate are added to the mobile phase in order to elute more strongly retained saccharides within an acceptable time frame. Figure 3.236 shows a respective chromatogram with carbohydrates that are relevant for the analysis of urine to assess kidney functionality. In addition to lactose and lactulose, these carbohydrates include weso-erythritol, mannitol, sucrose, and turanose. Under these chromatographic conditions, resolution between lactose and lactulose is so large that even an excess of lactose does not prohibit clear quantitation of lactulose. 

Tri- and tetrasaccharides such as raffinose and stachyose may be separated under the chromatographic conditions given in Figure 3.208. As with phosphorylated monosaccharides, shorter analysis times are obtained when adding sodium acetate to the eluent. The same holds for the analysis of tri-and tetrasaccharides of the kestose group, which also function as artificial sweeteners. 

We have developed a method for simultaneous analysis of thiamine hydrochloride, pyridoxine hydrochloride and cyanocobalamin in pharmaceuticals and dietary supplements (Marszall et al. 2005) and in fortified food (Lebiedzinska and MarszaH 2006) using HPLC-ED. Vitamins were determined in their free forms, so an extraction step from fortified fruit juice was performed prior to the chromatographic isolations. The extraction procedure was based on a study by Ndaw el al. (2000). The enzymatic digestion prior to the separation and quantification step made it possible to release the vitamins bound to proteins or sugars and converted vitamin esters to free forms thus we were able to obtain the total vitamin contents of the fruit juices. The supernatants were adjusted to pH 4.5 with 2.5 M sodium acetate and a single extraction procedure for all vitamins was carried out using mixture of the enzymes, papain and diastase (Lebiedzinska and MarszaH 2006). 

The United States Pharmacopoeia 23 [11] and Indonesian Pharmacopoeia IV [9] describe the assay of benzoic acid and salicylic acid in ointments. Two chromatographic columns (20 x 2.5 cm) are used to effect the separation. One transfers a mixture of 1 g siliceous earth and 0.5 mL diluted phosphoric acid (3 in 10) to the first column (A), then packs above this a mixture of 4 g siliceous earth and ferric chloride-urea reagent. A mixture of 4 g siliceous earth and 2mL of sodium bicarbonate solution (1 in 12) is packed into the second column (B). For analysis, column A is mounted directly above column B. The sample solution is inserted onto column A, allowed to pass into the column, and then washed with 2-40 mL of chloroform. Benzoic acid can be eluted from column B by using a 3 in 100 solution of glacial acetic acid in chloroform. The benzoic acid content then can be determined by a spectrophotometric method such as that described earlier (section 4.5). 

Formyl-2-methylfuran was converted in 75% yield into derivative 319 by electrolytic methoxylation. A corresponding mixture of cis-diols (320) was treated with Dowex W-50 ion-exchange resin in methanol for four days, to afford 5-deoxy-3-C-(dimethoxymethyl)-DL-eryf/rro-4-pentulose dimethyl acetal (321). Reduction of this compound with lithium aluminum hydride or sodium borohydride gave a mixture of 5-deoxy-3-C-(dimethoxymethyl)pentoses, which was separated by column chromatography on silica gel, to give206 DL-streptose tetramethyl acetal (322) and the isomeric 5-deoxy-3-C-(dimethoxy-methyl)-DL-ribose dimethyl acetal 323 (hjxo ribo = 13 7). Detailed, combined gas-liquid chromatographic-mass spectrometric analysis of the compounds related to streptose (in the form of their trimethyl-silyl derivatives) has been described.207... 

Paper partition chromatographic methods have been widely applied to the analysis of tetracyclines (128, 129). Pharmaceutical aqueous suspensions for oral use are acidified with HC1 and diluted with methanol. Crystalline formulations are dissolved only in methanol. A paper chromatographic method for TC determination in pharmaceutical preparations is based on the complexation of the antibiotic with a mixture of urea and disodium edetate on paper at pH 7.4. Urea helped in the separation of degradation products and led to the formation of well defined spots (130). Samples from fermentations must be acidified with oxalic acid to liberate TC from the mycelium. TC in filtrates may be precipitated in saturated solution of sodium tetraphenyl borate, precipitate dissolved in ethyl or butyl acetate and applied for paper chromatography. Various solvent systems and hRp values for paper chromatography are given in Table 4. 

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