Vydac

The chemical adsorption of a relatively high molecular weight neutral polymer (poly(succinimide), M = 13000) on aminopropyl-Vydac 101 TP silica gel was applied by Alpert [47, 48] to prepare a reactive composite support for use in cation-exchange [47] and hydrophobic-interaction [48] chromatography of pro-... 

Fig. 3. Cation-exchange chromatography of protein standards. Column poly(aspartic acid) Vydac (10 pm), 20 x 0.46 cm. Sample 25 pi containing 12.5 pg of ovalbumin and 25 pg each of the other proteins in the weak buffer. Flow rate 1 ml/min. Weak buffer 0.05 mol/1 potassium phosphate, pH 6.0. Strong buffer same +0.6 mol/1 sodium chloride Elution 80-min linear gradient, 0-100% strong buffer. Peaks a = ovalbumin, b = bacitracin, c = myoglobin, d = chymotrypsinogen A, e = cytochrom C (reduced), / = ribonuclease A, g = cytochrome C (oxidised), h = lysozyme. The cytochrome C peaks were identified by oxidation with potassium ferricyanide and reduction with sodium dithionite [47]...

Although some normal phase methods have been used, the majority of carotenoid separations reported in the literature were carried out by reversed phase HPLC. Among the Cjg columns employed for determination of complete carotenoid compositions in foods, the polymeric Vydac brand is preferably used for separation of cis isomers. Several examples of different C,g columns and mobile phases are cited in the literature, but not aU carotenoids are baseline separated in most systems. Table 6.2.1 shows some examples employing different brands of Cjg columns." Acetonitrile did not improve selectivity toward separation of carotene isomers in a Vydac 201TP column and resolution was strongly dependent on the Vydac column lot. ... 

Independently of the reversed phase column, the addition of TEA to the mobile phase increases carotenoid recovery from the column." Increased recoveries of 18% lutein, 33% zeaxanthin, 33% P-cryptoxanthin, 53% lycopene, 30% a-carotene, and 42% P-carotene in a Vydac column were observed after the addition of 0.1% TEA to the mobile phase. Recovery on a C30 column was also enhanced by the addition of 0.1% TEA to the mobile phase, with the peak area of lutein increasing by 26%, that of zeaxanthin by 42%, that of P-cryptoxanthin by 55%, that of lycopene by 21%, and those of a-carotene and P-carotene by 47 and 64%, respectively. ... 

Multiple electrodes have been used to obtain selectivity in electrochemical detection. An early example involved the separation of catecholamines from human plasma using a Vydac (The Separation Group Hesperia, CA) SCX cation exchange column eluted with phosphate-EDTA.61 A sensor array using metal oxide-modified surfaces was used with flow injection to analyze multicomponent mixtures of amino acids and sugars.62 An example of the selectivity provided by a multi-electrode system is shown in Figure 2.63... 

FIGURE 16.8 HPLC chromatogram of cytochrome c and myoglobin digest, using a 250 cm x 4.6 mm ODS C18 Vydac column and a linear mobile-phase gradient, 5-50% B, in 50 min. Buffer A was 0.1% TFA in water and buffer B was 0.1 TFA in acetonitrile. UV detection was carried out at 214 nm, at room temperature (reprinted with permission from Electrophoresis). 

LC-MS-MS was also the method of choice for the analysis of UV filters in solid matrices. Both LC and UPLC have been applied in three out of the four methods available for the determination of UV filters in sludge. Separation was performed on C8 and C18 LC-chromatographic columns (Zorbax, Eclipse, Vydac, and Purosphere) using binary gradient elution of mobile phases consisting of water/ methanol or water/acetonitrile. MS-MS detection was performed in SRM with ESI and atmospheric pressure photoionization (APPI) in both positive and negative modes. For each compound, two characteristics transitions were monitored. In addition to MS and MS-MS, diode array detection (DAD) was occasionally applied to the determination of OT. Spectra were recorded between 240 and 360 nm and discrete channels at 310 nm. 

BA 3,4-dihydrodiol metabolites were isolated by a reversed-phase HPLC using a Vydac C18 column (Chiu et al., unpublished results). DMBA dihydrodiol metabolites were isolated as described (42). The enantiomeric composition was determined either by CD spectral data or by CSP-HPLC (7.19.20). 

Fig. 18a-c. Base peak chromatograms for the LC/MS analyses of a cytochrome c Lys-C digest (0.7 pmol injected) on a a poly(styrene-co-divinylbenzene) monolith-filled needle b Vydac C18-packed needle c Poros R2-packed needle. (Reprinted with permission from [128]. Copyright 1998 American Chemical Society)... 

Procedure The HPLC is carried out using (a) a Vydac C18 column, for proteins and peptides, maintained at 40 °C, (b) as the mobile phase at a flow rate of 1 ml per minute, a mixture of 48 volumes of mobile phase A and 52 volumes of mobile phase B prepared and maintained at a temperature of not less than 20 °C, and (c) a detection wavelength of 214 nm. 

Kele, M. and Guiochon, G. Repeatability and Reproducibility of Retention Data and Band Profiles on Reversed-phase Liquid Chromatography Columns. V. Results Obtained with Vydac 218TP C18 Columns,/. Chromatogr. A, 913 89—112, 2001. 

NP chromatography is unable to separate vitamin D2 from vitamin Dj. So it is usually used as semipreparative chromatography [527-531]. Instead, RP chromatography is able to resolve vitamin D2 and Dj, thus it is widely applied as aualy tical chromatography. Mattila et al. [532] describe a two dimensioual LC procedure. The sample is saponified and an NP semipreparative column is used before the quantification in a tandem column set (Zorbax ODS x Vydac 201 TP54 CIS). 

Figure 1 HPLC Profiles of Crude (a) and Purified (b) Fully Protected Segment 1. Column Vydac Diphenyl (250 x 4.6 mm) Eluant 80-90% Solution B in Solution A Linear Gradient for 25 min. HPLC Profiles of H-Asn103-Val124-OH Cys(Acm)110 (c) and (d) Obtained from Deprotection of Crude (a) and Purified (b) Fully Protected Segment 1, Respectively. Column Vydac C8(250 x 4.6 mm) Eluant 20 10% Solution B in Solution A Linear Gradient 25 min (Solution A 0.1% aq TFA and Solution B 90% MeCN/10% Solution A) Detection 215 nm...

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