Eluents tyrosine

Separation of Extracts from Chlorination of Tyrosine and Phenylalanine. Separation was by reversed-phase HPLC by using Spherisorb-ODS (25 cm X 4.6 mm i.d.) with an eluent of 35 methanol in water for the chlorinated tyrosine extract and 55 methanol in water for the chlorinated phenylalanine extract. 

Figure 6. Reverse-phase HPLC chromatograms from XAD-2/ethyl ether extracts of (a) chlorinated phenylalanine and (b) chlorinated tyrosine. An eluent of 55% methanol in water was used in (a), and an eluent of 35% methanol in water was used in (b).

Fig. 8.3. Isocratic (a) and gradient (b) separation of PTH amino acids. Column, 250 x 0.075 mm i.d. packed with 3.5 p.m/80 A Zorbax ODS eluents, (A) 2 mmol/1 ammonium acetate, pH 7.0, (B) 2 mmol/1 ammonium acetate, pH 7.0, 90% acetonitrile isocratic elution with 30% B in (a) gadient elution with 30-80% B in 5 min, followed by 80% for 5 min in (b) flow rate of mobile phase through inlet reservoir, 100 pl/min applied voltage, 15 kV Detection, ESI-MS, m/z 100-2000, 0.5 s/spectrum integration time sheath liquid, 1 mmol/1 ammonium acetate, pH 7.0, 90% methanol, 3 pl/min injection, electrokinetic, 2 kV, 2 s sample, PTH-asparagine, PTH-glutamine, PTH-threonine, PTH-glycine, PTH-tyrosine, PTH-alanine (in order of elution). (Reproduced from ref. [82] with permission of Elsevier Sciences B. V.).

Fig. 10.17. Capillary electrochromatography of PTH-amino acids with gradient elution. Column, 207 (127) mm x 50 pm i.d. packed with 3.5 pm Zorbax ODS particles, 80 A pores. Starting eluent (A), 5 mM phosphate, pH 7.55, 30% acetonitrile gradient former (B), 5 mM phosphate, pH 7.55, 60% acetonitrile flow-rate (through inlet reservoir), 0.1 ml/min gradient, 0-100% B in 20 min voltage 10 kV current, 1 pA temperature, 25°C UV detection at 210 nm electrokinetic injection, 0.5 s, 1 kV. Peaks in order of elution formamide PTH-asparagine PTH-glutamine PTH-threonine PTH-glycine PTH-alanine PTH-tyrosine PTH-valine PTH-proline PTH-tryptophan PTH-phenyialanine PTH-isoleucine PTH-leucine. The concentration of the PTH-amino acids dissolved in the mobile phase was 30-60 pg/ml. Reprinted with permission from Huber et al. [68]. Copyright 1997 American Chemical Society.

Fig. 1 Dependence of k on adrenaline (squares) and L-tyrosine hydrazide (circles), on mobile-phase concentration of 1-hexane-sulfonate. Column Synergi Hydro-RP (Phenomenex) 150 x 4.6 mm ID, particle size 4 pm, and bonded phase coverage 4.05 pmol/m. Eluent phosphate buffer 37.10 mM KH2PO4 and 4.29 mM Na2HP04 calculated to provide a pH of 6.0. After addition of the desired amount of sodium 1-hexanesulfonate, NaCl was added so that the total sodium concentration was 50 mM (constant ionic strength). Experimental data were fitted by Eq. 8.

The aromatic amino acid tyrosine has proved successful as an eluent for the simultaneous analysis of all halide anions, which also causes a reduction in the iodide retention at alkaline pH, while still allowing for the separation of bromide and nitrate in contrast to p-cyanophenol containing eluents. In the respective chromatogram obtained with tyrosine as the eluent, a reversed retention is observed for orthophosphate and sulfate. This is caused by the comparatively high pH value of the mobile phase. The... 

Fig. 3-53. Separation of halide ions using tyrosine as the eluent. - Separator column IonPac AS4A eluent 0.001 mol/L tyrosine + 0.003 mol/L NaOH flow rate 2 mL/min detection suppressed conductivity injection volume 50 pL.

To a suspension of 2.0 g A -Boc-L-tyrosine (7.12 mmol) and 0.256 mL water in 30 mL CHCI3 was added 1.71 g powdered NaOH (42.72 mmol). After the mixture was refluxed for 4 h, an additional 0.42 g NaOH (10.68 mmol) was added over 1.5 h. The reaction was then diluted with water and EtOAc, and the aqueous layer was acidified to pH 1 with 1 N HCl and back extracted with EtOAc. The combined organic layers were washed with brine, dried over MgS04, and concentrated. Flash column chromatography using CHCH/MeOH (12 1) with 1% acetic acid as the eluent afforded 0.72 g A-[(l,l-dimethylethoxy)-carbonyl]-3-(3-formyl-4-hydroxyphenyl)-L-alanine (33%) and 0.62 g A-Boc-L-tyrosine (31% recovery). 

Figure 4 HPLC separation of 17 PTC AAs (Pico-Tag column 150 x 3.9mm, eluent A 0.14moll NaAc, pH 6.4, containing 0.5ml TEAI B 60% acetonitrile in water flow rate 1 ml minpeaks 1 = aspartic, 2=glutamic acids, 3 = serine, 4=glycine, 5=his-istidine, 6 = arginine, 7=threonine, 8 = alanine, 9 = proline, 10 = ammonia, l1=tyrosine, 12=valine, 13=methionine, 14=cystine, 15 = isoleucine, 16 = r>leucine, 17 = phenylalanine, 18=tryptophan. (Reproduced with permission from Bidlingmayer BA ef a/. (1984) Journal of Chromatography 336 Elsevier.)...

Figure 5 Separation of 27 PTC AAs (column 150+ (20 guard) x 4 mm, Cl 8 Hypersil Sum, T=50°C, eluent A 0.05 mol I" NaAc, pH 7.2, B A eluent/acetonitrile/methanol = 46/44/10 (pH 7.2) flow rate 2.1 ml min peaks 1 = aspartic, 2 = glutamic acids, 3 = hy-hydroxyproline, 4 = serine, 5 = glycine, 6 = asparagine, 7 = -alanine, 8 = glutamine, 9 = homoserine, 10 = y-aminobutyric acid (GABA), 11 =histidine, 12 = threonine, 13 = alanine, 14 = 1-amino-1-cyclopropane carboxylic acid (ACPCA), 15 = arginine, 16 = proline, 17 = homoarginine, 18 = tyrosine, 19 = valine, 20 = methionine, 21 =cyst(e)ine, 22 = isoleucine, 23=n-leucine, 24 = phenyl-ylalanine, 25 = tryptophan, 26 = ornithine, 27 = lysine = system peaks. (Reproduced with permission from Vasanits A and Molnar-Perl I (2000) Journal of Chromatography A 870 271-287 Elsevier.)...

Contrary to PS, polyacrylamide is a hydrophilic polymer. This may increase the ligand exchange rate, i.e., the column efficiency. Thus on the polyacrylamide-CH2-L-pro-line-Cu(II) macroporous microspheres, the enantiomers of valine, threonine, isoleucine, serine, phenylalanine, tyrosine, tryptophan, and asparagine were completely resolved in less than 1 hr with water as the eluent. The efficiency was markedly improved. However, the methylene bridge between the ligand and the matrix was not stable under acidic and basic conditions. The same sorbent, but with a long spacer, -CH2CH20CH2CH(0H)CH2-, was prepared with L-proline content 1.76 mmol/g of dry polymer." When the polymer was soaked in 0.1 M HCl, 0.1 M NaOH or 1 M NH3, aqueous solutions, respectively, at... 

Caude and co workers [722] used Pirkle-type tyrosine linked dinitrobenzene stationary phases (X = 254 nm) to study the resolution of the enantiomers of alkyl-AT-arylsulfinamoyl esters. To optimize the separation, various ratios of 98/8 hexane/ethanol and 50/50 hexane/chloroform were mixed to form a ternary eluent An informative plot of capacity factor and separation factor is presented for one compound and a table of retention and selectivity is given for various hexane/polar solvent mixtures (polar solvent=ethanol, IPA, chloroform, or dichloromethane). 

Figure 3.129 Separation of halide ions with a tyrosine eluent on a poly(styrene-co-divinyl-benzene)-based anion exchanger. Separator column lonPac AS4A-SC eluent 1 mmol/L tyrosine + 3 mmol/L NaOH flow rate 2 mL/...

Arogenic acid is not stable at acidic pH. Thus, it cannot be analyzed by cation-exchange chromatography. However, on a nanobead-agglomerated anion exchanger with alkaline eluents, the separation of this compound from the amino acids phenylalanine and tyrosine is accomplished without any problem. 

The research listed in Table 2 (81-98) deals mainly with separation problems concerning amino acids, amino acid derivatives, and dipeptides, focusing on the influence of the structure of the chiral support and the eluent temperature on the separation behavior of the racemates. Separation of the aromatic amino acids phenylalanine, P-2-thienylalanine, 4-fluorophenylalanine, and tyrosine could not be achieved on microcrystalline or amorphous cellulose tryptophan isomers, however, could be reproducibly resolved on microcrystalline cellulose layers (83). Lowering the eluent temperature from 30 C to O C enhances enantiomeric resolution. However, developing times of 10 1 h (O C), 7.5 0.5 h (10°C), 5 0.5 h (20°C), and 3.5 h (30°C) have to be tolerated hydrophobic eluent combinations further enhance separation, because they improve formation of the helical cellulose conformation (87). Separation of racemic 3,4-dihydroxyphenylalanine, tryptophan, and 5-hydroxy-tryptophan can be achieved in only 2 h, on a cellulose HPTLC plate (89) these experiments will be described in detail in Section FV.C. 

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