Hydrophilic interaction method development

We use the second-dimension separation from Fig. 6.6 with a 25 pL injection volume and 2.5 min sampling time the separation is an RPLC method that uses a monolithic column. Thus, 10 pL/min is the maximum flow rate in the first-dimension. Fig. 6.7 shows the development of the first-dimension column that utilizes a hydrophilic interaction (or HILIC) column for the separation of proteins at decreasing flow rates. The same proteins were separated in Fig. 6.6 (RPLC) and 6.7 (HILIC) and have a reversed elution order, which is known from the basics of HILIC (Alpert, 1990). It is believed that HILIC and RPLC separations are a good pair for 2DLC analysis of proteins as they appear to have dissimilar retention mechanisms, much like those of NPLC and RPLC it has been suggested that HILIC is similar in retention to NPLC (Alpert, 1990). Because the HILIC column used in Fig. 6.7 gave good resolution at 0.1 mL/min and no smaller diameter column was available, the flow was split 10-fold to match the second-dimension requirement... 

A selective, sensitive, and rapid hydrophilic interaction liquid chromatography with electrospray ionization tandem mass spectrometry was developed for the determination of donepezil in human plasma [32], Donepezil was twice extracted from human plasma using methyl-ferf-butyl ether at basic pH. The analytes were separated on an Atlantis HILIC Silica column with the mobile phase of acetonitrile ammonium formate (50 mM, pH 4.0) (85 15, v/v) and detected by tandem mass spectrometry in the selective reaction monitoring mode. The calibration curve was linear (r = 0.9994) over the concentration range of 0.10-50.0 ng/ ml and the lower limit of quantification was 0.1 ng/ml using 200 /d plasma sample. The CV and relative error for intra- and inter-assay at four quality control levels were 2.7% to 10.5% and —10.0% to 0.0%, respectively. There was no matrix effect for donepezil and cisapride. The present method was successfully applied to the pharmacokinetic study of donepezil after oral dose of donepezil hydrochloride (10 mg tablet) to male healthy volunteers. 

Naidong W, Eerkes A (2004) Development and validation of a hydrophilic interaction liquid chromatography-tandem mass spectrometric method for the analysis of paroxetine in human plasma. Biomed Chromatogr 18 28-36... 

Epitopes presented in constrained scaffolds may be prevented from optimal interactions with their target by local deleterious charge, hydrophobic, hydrophilic or steric interactions. Methods have, therefore, been developed which introduce hypervariability, not only into the highly variable epitopes but also into the framework which carries them. This has been achieved by the use of error-prone PCR or, more recently, in vivo hypermutation. Ouellette and Wright [100] in their review of PCR amplifiable DNA and RNA ligands,... 

The choice of eluent system depends on the polymer type. For most non-ionic hydrophilic polymers, water can be used. However much more complex eluent systems are needed, for anionic and cationic polymers where interactions with the column based on ion exclusion, inclusion and exchange, adsorption by hydrogen bonding or hydrophobic interactions and intramolecular electrostatic effects, are possible. This can often make method development in aqueous SEC extremely difficult and time-consuming. 

Because of the development of analytical methods for determination of MC, especially in last decade, the most widespread analytical techniques for their determination are commercialized enzyme-linked immunosorbent assays and HPLC with diode array detectors of anion-exchange columns for this purpose were only sporadically reported with UV detection and isocratic or gradient ° elution. For anion-exchange stationary phase functionalized with diethylaminoethylene groups, better resolution for LR and YR was reported than for Cl8 columns.For separation of cyanobacterial toxins, including MC-LR and -RR, hydrophilic interaction HPLC with gel Amide-80 column and amide C16 column providing comparable resolution to that of conventional reversed-phase Cl8 columns were applied. 

Karson, G. (2011) Development and application of methods for separation of carbohydrates by hydrophilic interaction liquid chromatography, in Hydrophilic Interaction Liquid Chromatography (HILIC) and Advanced Applications (eds P.G. Wang and W. He), CRC Press, Boca Raton, p. 491. 

The present edition is considerably updated and expanded, covering all aspects of ion chromatography and all developments in this field that have been introduced over the past 10 years. This includes the application of hydrophilic interaction and mixed-mode liquid chromatography for the determination of ionic and ionizable compounds, the introduction of novel detection methods and hyphenated techniques, the design of new separation media for capillary and monolithic columns, columns packed with particulate ion exchangers having smaller particle diameters, and mixed-mode stationary phases. 

The present author has developed a novel method called ion-association method. This is also a simple and versatile method for the preparation of ion-based organic dye nanoparticles in pure aqueous solution by the ion association approach [23]. It utilizes the control of hydrophilicity/hydrophobicity of the ionic material itself via ion-pair formation for example, addition of a cationic target dye solution into aqueous solution containing a certain kind of hydrophobic anions forms an electrically neutral ion-pair because of the strong electrostatic attraction, followed by aggregation of ion-pair species originated from van der Waals attractive interactions between them to produce nuclei and the subsequent nanoparticles (Fig. 3). In this case, hydrophobic but water-soluble anions, such as tetraphenyl-borate (TPB) or its derivatives (tetrakis(4-fluorophenyl)borate (TFPB), tetrakis [3,5-... 

One method for the labeling of liposomes with chelator, hexamethylpropyleneamine oxime (HMPAO) was developed by Phillips et al. (16). Lipophilic HMPAO enters the liposome where it interacts with glutathione and becomes converted to the hydrophilic form, which is trapped in the liposome. A detailed protocol for radiolabeling liposomes using Tc-HMPAO has been reported (3). In a typical experiment, 10 to 15mCi (370-555 MBq) of Tc in the form of sodium pertechnetate... 

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