Eluents sodium hydroxide/methanol

A mixture of 4-[4-(diphenylmethyl)-l-piperazinylmethyl]-Nl-ethyl-l,2-benzenediamine and acetic acid is stirred at room temperature till all solid enters solution. Then there are added pentyl ethanimidate hydrochloride and stirring is continued first for 1 h at room temperature and further for 1 h at reflux. The reaction mixture is evaporated and the residue is stirred in water. The whole is alkalized with a sodium hydroxide solution and the product is extracted with dichloromethane. The extract is dried, filtered and evaporated. The residue is purified by column-chromatography over silica gel using a mixture of trichloromethane and methanol as eluent. The pure fractions are collected and the eluent is evaporated. The product is filtered off and dried, yielding 5-[4-(diphenylmethyl)-l-piperazinylmethyl]-l-ethyl-2-butyl-lH-benzimidazole melting point 124.8°C (crystallized from 4-methyl-2-pentanone). 

To an ice-cooled solution of N-methyl-l-naphthalenemethylamine hydrochloride (2.1 g) in methanol (40 ml) and water (10 ml) was added sodium hydroxide powder (2 g) followed by dropwise addition of epichlorohydrin (8 ml). The mixture was heated at 60°C for 3 h, then cooled to room temperature. Volatile materials were removed in vacuo and the residue was taken up in ethyl acetate and washed with water. The organic phase was collected, dried over sodium sulfate, filtered and evaporated to dryness. The crude mixture was purified by flash chromatrography on silica gel (grade 9385, Merck, 230-400 mesh, 60 A) using a solvent gradient of a mixture of hexane and ethyl acetate (95 5, 90 10 and 85 15) as eluent, affording the N-methyl-N-naphthylmethyl-2,3-epoxypropane (1.85 g, 81.5%) as an oil. 

Fig. 8.23. CEC—ESI-MS analysis of steroids. Column, 450 x 0.1 mm i.d. packed with 3 pm Sherisorb ODS-1 eluent, 4 mmol/1 sodium tetraborate-sodium hydroxide, pH 8.0, 70% acetonitrile applied voltage, 21.5 kV detection, ESI-MS, 370-470 amu sheath liquid, 0.1% formic acid, 50% methanol, 6 pl/min injection, electrokinetic, 5 kV, 10 s sample, bufalin, cinobufagein, digitoxigenin, cinobufatalin, digoxigenin, gitoxigenin (in order of elution). (Reproduced from ref. [81 ] with permission of John Wiley Sons.).

Eluent. A solution containing 1.175 g (0.01 M) of ammonium perchlorate in 1000ml of methanol adjust to pH 6.7 by the addition of 1 ml of 0.1 M sodium hydroxide in methanol. k Values. Values for drugs in this system will be found in drug monographs and in the indexes to Analytical Data in Part 3 they are also included in the systems for specific groups of drugs which follow. 

Fig. 7.5. Effect of variation of the eluent pH upon elution volume. Chromatographic conditions column, pBondapak Cjg (10 pM) (300 mmX4 mm I.D.) mobile phase, eluent solutions (pH 3.0, 5.0, 7.0 and 9.0) were made up from 0.025 M NaH2P04 and/or 0.025 M Na2HP04 solutions plus 40% methanol (solutions were adjusted to final pH by the addition of 5% sodium hydroxide or phosphoric acid solution) detection, UV at 220 nm. , salicylic acid a, phenobarbitone a, phenacetin O, nicotine , methylamphetamine. Reproduced from Twitchett and Moffat (1975), with...

Table 1 shows the separation of alcohols (2,3-butanediol, ethanol, methanol), glycols (glycerol), alditols (erythritol, arabitol, sorbitol, galactitol, mannitol), and carbohydrates (rhamnose, arabinose, glucose, galactose, lactose, sucrose, raffinose, maltose) using a CarboPac MAI column set with 480 mM sodium hydroxide eluent... 

Desacetylmetipranolol, the active metabolite of metipranolol (Figure 6.43), has been measured by HPLC-ED after LLE of plasma with dichloromethane. An ODS-modified silica column was used with methanol-phosphoric acid (50mmolL ) (4 + 6) containing disodium EDTA (lOmgL ) as eluent. The final pH was adjusted to 3.0 with aq. sodium hydroxide. Detection was at a GCE (+0.9 V V5 Ag/AgCl). Pindolol (Figure 6.41) was the internal standard. 

Lippi et measured idrapril (Figure 6.49) in urine (human and rat) and tissues (rat) at PGEs (Ei +0.4 V, E2 +0.8 V Pd) after analysis on an ODS-modified silica column. The eluent for urine and tissue work was acetonitrile-methanol-orthopho-sphoric acid (1% v/v, adjusted to pH 3 with 6molL aq. sodium hydroxide)... 

The use of HPLC-ED in the analysis of the anabolic steroids and metabolites, diethylstilbestrol, taleranol, zearalenol, zearalenone and zeranol (Figure 7.5), in mammalian tissue has been discussed.Diethylstilbestrol has been measured in animal tissue using an ODS-modified silica column with methanol-aq. phosphate buffer (50 mmol L pH 3.5) (67 + 33) as eluent and ED (GCE, +0.9 V vs Ag/ AgCl). Sample homogenisation was followed by LLE into MTBE, back-extraction into aqueous sodium hydroxide and SPE (ODS-modified silica). The LoD was approximately 0.5 pg kg wet weight (10 g sample). Clenbuterol assay in calf urine was discussed above (Chapter 6, Section 2). 

To a solution of the enol lactone 25 (1 mmol) in anhydrous tetrahydrofiiran (3 mL) was added the appropriate Grignard reagent (1.5 mmol) in ethereal solution at -60 °C over 30 min. After stirring at -60 °C for 1 h, the reaction mixture was poured onto saturated ammonium chloride solution, and the reaction product extracted with diethyl ether. The organic extract was washed and dried (sodium sulfate). After removal of the solvent, the residue was dissolved in 2 N methanolic potassium hydroxide solution (4 mL), and the resultant mixture heated under reflux for 1 h. The cooled mixture was neutralised with AcOH and evaporated under reduced pressure. The residue was then diluted with water and extracted with diethyl ether or dichloromethane. Chromatography of the crude product on silica gel (eluent 3 7 ethyl acetate/hexanes) afforded pure enones 26 in 20-50% yields. 

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