Determination by HPLC

The enantiomeric excess of 3.10c has been determined by HPLC analysis using a Daicel Chiracel OD column and eluting with a 60 / 1 (v/v) hexane(HPLC-grade) / 2-propanol(p.a.) mixture. At a flow of 1 ml per minute the rentention times for the different isomers of 3.10c were 6.3 min. (exo, major enantiomer) 7.1 min. (exo, minor enantiomer) 7.7 min. (endo, major enantiomer) 10.7 min. (endo, minor enantiomer). 

The amount of caffeine in an analgesic tablet was determined by HPLC using a normal calibration curve. Standard solutions of caffeine were prepared and analyzed using a lO-pL fixed-volume injection loop. Results for the standards are summarized in the following table. 

Before polyacrylamides are sold, the amount of residual acrylamide is determined. In one method, the monomer is extracted from the polymer and the acrylamide content is determined by hplc (153). A second method is based on analysis by cationic exchange chromatography (154). For dry products the particle si2e distribution can be quickly determined by use of a shaker and a series of test sieves. Batches with small particles can present a dust ha2ard. The percentage of insoluble material is determined in both dry and emulsion products. 

Various methods for the glc monitoring of EPA Consent Decree Priority PoUutants in water have been described (36) (see Regulatory agencies). The deterrnination of organic poUutants in water by glc and ms methods has also been detailed (37,38). Nonvolatile organic compounds in drinking water have been determined by hplc (39) (see Water, pollution). 

The theobromine and caffeine contents of several finished chocolate products as determined by hplc at Hershey s laboratories are presented in... 

Using 282a as a standard, the neoascorbigen content in kohlrabi is determined by HPLC. 

Determined by HPLC (Daicel Chiral Cei OD-H). fl,fl-DBFOX/Ph was added to a mixture of Ni(CI04)2-6H20, thiophenoi, and 3-crotonoyl-2-oxazolidinone. 

At 03C, a solution of 120 mg (1.2 mmol) of phenylacetylene in 2 mL of dry Et20 is treated with 0.45 mL (1.2 mmol) of 2.6 M BuLi in hexane, The mixture is stirred for 30 min, then a solution of 290 mg (1.3 mmol) of anhyd zinc bromide in 2 mL of Et20 is added. After cooling to —78 C, 100 mg (0.6 mmol) of 2-(ben-zyloxy)propanal (7) are added and the reaction mixture is allowed to warm to 0 C over a 2-h period. The reaction is quenched with sat. aq NH4C1. The organic layer is separated, dried over Na2S04 and concentrated. The residual oil is purified by column chromatography on silica gel yield 154 mg (95%) d.r. (syn/anti) 95 5 (determined by HPLC). 

To a solution of 516 nig (1 mmol) of the stannane 17 (R = C.H3, 95% ee) in 10 ml of dry DME is added, at — 78 C, 0.62 nlL of 1.6 M BuLi (1 mmol) in hexane. After 5 min gaseous carbon dioxide is bubbled into ihe yellow solution. The reaction mixture decolorizes immediately. After a further 10 min the reaction is quenched with sat. aq NH4C1. The organic layer is extracted with 2N aq NaOll. Acidification of the aqueous layer with 2N aq IICI is followed by extraction with F.t,o, drying over Na,SC)4 and concentration in vacuo yield 193 mg (92%) 95% ec [determined by HPLC-analysis of the amide obtained by derivati/alion with (S)-x-phenylelhylaminc] [a]20 — 37 (r = 1,6, CI1C1,). 

In a flame-dried Schlenk tube 0.37 g(1.88 mmol) of (-)-3-exo-(dimethylamino)isoborneol (C) and 200 mL of dry toluene are placed under an atmosphere of argon. 27 mL of 4.2 M diethylzinc (113 mmol) in toluene are added and the resulting solution is stirred at 15°C for 15 min. After cooling to — 78°C, lOg (94.2 mmol) of benzaldehyde are added and the mixture is wanned to O C. After stirring for 6 h, the reaction is quenched by the addition of sat. NH4C1 soln. Extractive workup is followed by distillation yield 12.4 g (97%) 98% ee [determined by HPLC analysis. Baseline separation of rac-1 -phenyl-1 -propanol was achieved on a Bakerbond dinitrobenzoyl phenylglycine column (eluent 2-propanol/hexanc 1 3 flow rate l.OmL/ min detection UV 254 nm)] [a] 0 —47 (c = 6.11, CHC13). 

Sl-a-Phenylethylaminc (2a 94% ee) and (.S)-2-heptylamine (2b 82% ec) were synthesized from enantiomerically pure nitrones 1 a and 1 b (33-39% overall yield). The enantiomeric purity of the amines was determined by HPLC analysis of their 3,5-dinitrobenzamidines on a D-naphthyl alanine column,... 

Although the (/ )-diastercomer is the minor component, as directly determined by HPLC it crystallizes from the solution of the diastereomeric mixture of the JV-galactosyl-tm-leucinonitriles63. 

Determined by HPLC using diode array detection of a sample taken directly from the reaction mixture. b (< = 1, CHClj). 

A solution of 0.858 g (5.5 mmol) of 4-(1-methyl-l-butenyl)morpholine and 0.75 g (5.0 mmol) of ( )-(2-ni-troethenyl)benzene in 10 mL of diethyl ether is kept at r.t. for 4d. The solution is then evaporated and treated with a mixture of 13 mL of ethanol and 15 mL of 10% aq hydrochloric acid for 1 h at 25 C. The solution is extracted with CH2C12 and the organic phase is washed with aq Nall CO, then with water and dried over MgSO . Evaporation gives 1.04 g of an oil which is purified by column chromatography (silica gel. hexanc/cthyl acetate 10 1) to give the pure title compound as an oil yield 0.90g (77%). The diastereomeric ratio is determined by HPLC (methanol/water 4 1, reverse phase RP8) to be 93 7. 

A flame-dried flask under argon containing a 0.08 M THF solution of 317 mg (1.0 mmol) of the 2-(l- or 2-naphthyl)-substituted 4,5-dihydrooxazole is cooled to a temperature of between — 80 and 0 CC (see ref 7) and is treated with 1.5-2.0 equiv of the alkyllithium. The solution becomes deep red over 2-4 h and is quenched by the dropwise addition of 1.5 equiv of the electrophile (either neat or as a THF solution). The temperature is maintained for 1 h and then the solution is warmed gradually to 0 JC. The solution is diluted with 100 mL of diethyl ether and washed with 5 mL of sat. NH4C1, followed by 3 mL of sat. aq NaCI. The combined aqueous layers are back-extracted with 10 mL of CII2C12, and the combined extracts are dried over Na2S04. Concentration of the filtrate in vacuo provides a yellow oil, which is flash chromatographed over silica gel (1 -10% ethyl acetate in hexane) to yield the desired adducts. The diastereomeric ratios are determined by HPLC (Zorbax Sil column, Du Pont). 

The molecular weights of PAs are often not very high (M > 20,000) in this range M can be determined by endgroup analysis or, less frequently, by osmometry, Mw can be determined by light scattering. Both M and Mw can indirectly be determined by HPLC. 

Phengl-2(lH)Pyridone-Propylsulfonate Sodium Salt Vllb. A solution of 3-phenyl-2(lH)pyridone sodium salt (0.264 g, 1.25 mmol) and 3-bromopropylsulfonate sodium salt (0.241 g, 1.25 mmol) in acetonitrile (650 mL) was brought to reflux with stirring for 24 h. The yield was 41%, as determined by HPLC. An analytical sample was obtained from the filtered residue of reaction by preparative HPLC. Anal. Calcd for Ci4Hi4NS04Na H2O C, 50.45 H, 4.8 N, 4.2. Found C, 50.38 ... 

A regio- and stereoselective Beckmann rearrangement utilized diastereose-lective host guest interactions of the inclusion complexes 225 and 228 in a solid state reaction. Initially, a 1 1 mixture of the chiral host 223 and the racemic oximes 224 and 227, respectively, was treated with ultra sound in the solid state to induce the optical resolution. Then H2SO4 was added to start the Beckmann rearrangement, the corresponding c-caprolactams 226 and 229 were isolated in 68 % and 64 % yields and ee of about 80 % and 69 % (determined by HPLC analysis on chiracel OC) (Scheme 43) [46]. 

The complex 65 was synthesized by reaction of the imidazolinium salt with the precursor ruthenium complex 67 (catalytically inactive) in the presence of silver carbonate (Scheme 42). The complex being air-stable and stable on silicagel was isolated in 52% yield after chromatography. The diastereomeric and enantiomeric purity of 65 was determined by HPLC analysis and found to be above 98% (de and ee). The molecular structure was determined by X-ray analysis and showed the unusual twist geometry of this complex. 

The concentrations of lactic acid and other organic acid species were determined by HPLC CTOlOA... 

Data from Hasegawa et at. (1992). Determined by hplc on an optically active phase, "rt = room temperature. 

Leitao, M. C. A. Alarcao-Silva, M. L. Januario, M. I. N. Azinheira, H. G. Galacturonic acid in pectic substances of sunflower head residues quantitative determination by HPLC. Carbohydr. Polym.,26(1995)165-169. 

Determined by HPLC or H NMR in the presence of chiral europium (111) tiis[3-(heptafluoro-propylhydroxy- methylene)-(+)-camphorate]... 

Slater, B., McCormack, A., Avdeef A., Comer, J. E. pH-metric logP. 4. Comparison of partition coefficients determined by HPLC and potentiometric methods to literature values. J. Pharm. 

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