Molecular imprinting science and technology: a survey of the literature for the years up to and including 2003

Separation of polar compounds on polar stationary phases with partly aqueous eluents is by no means a new separation mode in LC. The first HPLC applications were published more than 30 years ago, and were for a long time mostly confined to carbohydrate analysis. In the early 1990s new phases started to emerge, and the practice was given a name, hydrophilic interaction chromatography (HILIC). Although the use of this separation mode has been relatively limited, we have seen a sudden increase in popularity over the last few years, promoted by the need to analyze polar compounds in increasingly complex mixtures. Another reason for the increase in popularity is the widespread use of MS coupled to LC. The partly aqueous eluents high in ACN with a limited need of adding salt is almost ideal for ESI. The applications now encompass most categories of polar compounds, charged as well as uncharged, although HILIC is particularly well suited for solutes lacking charge where coulombic interactions cannot be used to mediate retention. The review attempts to summarize the ongoing discussion on the separation mechanism and gives an overview of the stationary phases used and the applications addressed with this separation mode in LC.

Hydrophilic interaction chromatography.

Hongyuan Yan and Kyung Ho Row* Center for Advanced Bioseparation Technology, Department of Chemical Engineering, Inha University, 253 Yonghyun-Dong, Nam-Ku, Incheon, 402–751, Korea * Corresponding author. E-mail: rowkho@inha.ac.kr Received: 12 April 2006 / Accepted: 27 June 2006 / Published: 29 June 2006 Abstract: Molecularly imprinted polymers (MIP) exhibiting high selectivity and affinity to the predetermined molecule (template) are now seeing a fast growing research. However, optimization of the imprinted products is difficult due to the fact that there are many variables to consider, some or all of which can potentially impact upon the chemical, morphological and molecular recognition properties of the imprinted materials. This review present a summary of the principal synthetic considerations pertaining to good practice in the polymerization aspects of molecular imprinting, and is primarily aimed at researcher familiar with molecular imprinting methods but with little or no prior experience in polymer synthesis. The synthesis, characteristic, effect of molecular recognition and different preparation methods of MIP in recent few years are discussed in this review, unsolved problems and possible developments of MIP were also been briefly discussed. Keywords: molecularly imprinted polymer, special molecular recognition, synthetic approach 1. Molecular Imprinting Technology Molecular imprinting technology is a rapidly developing technique for the preparation of polymers having specific molecular recognition properties for a given compound, its analogues or for a single enantiomer [1-3]. Synthesis of MIP is a relatively straightforward and inexpensive procedure. In short, the molecularly imprinted polymer is prepared by mixing the template molecule with functional monomers, cross-linking monomers and a radical initiator in a proper solvent, most often an aprotic and non polar solvent. Subsequently, this pre-polymerization mixture is irradiated with UV light or

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Characteristic and synthetic approach of molecularly imprinted polymer

Separation efficiencies in hydrophilic interaction chromatography.

CE has been alive for over two decades now, yet its sensitivity is still regarded as being inferior to that of more traditional methods of separation such as HPLC. As such, it is unsurprising that overcoming this issue still generates much scientific interest. This review continues to update this series of reviews, first published in Electrophoresis in 2007, with updates published in 2009 and 2011 and covers material published through to June 2012. It includes developments in the field of stacking, covering all methods from field amplified sample stacking and large volume sample stacking, through to isotachophoresis, dynamic pH junction and sweeping. Attention is also given to online or inline extraction methods that have been used for electrophoresis.

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Recent advances in enhancing the sensitivity of electrophoresis and electrochromatography in capillaries and microchips (2016–2018)

Fast and precise determination of phenthoate and its enantiomeric ratio in soil by the matrix solid-phase dispersion method and liquid chromatography.

Separation of peptides by pressurized capillary electrochromatography

The separation of enantiomers and diastereomers of 8 commonly used pesticides was investigated by liquid chromatography (LC) using a Chiralcel OD column (cellulose tris-3,5-dimethylphenylcarbamate as the chiral stationary phase) and a Pirkle-type Chirex 3020 column (urea derivative from the reaction of (R)-1-(alpha-naphthyl)ethylamine with (S)-tert-leucine, chemically bonded to 3-aminopropylsilanized silica as the chiral stationary phase). The pesticides studied included one organophosphorus insecticide (phenthoate), 3 triazole fungicides (uniconazole, diniconazole, and propiconazole), and 4 pyrethroids (fenpropathrin, beta-cypermethrin, beta-cyfluthrin, and alpha-fenvalerate). The enantiomers were separated within 20 min with a resolution of > or = 1.5 using a mixture of n-hexane and 2-propanol as the mobile phase for all the pesticides studied except propiconazole, for which only the 2 diastereomers were baseline separated. This method allows determination of the enantiomers or stereoisomers of the above pesticides in soil. The strategy was as follows: (1) First, the total concentration(s) of the enantiomer pair(s) of a chiral pesticide in soil was (were) determined by a newly developed matrix solid-phase dispersion (MSPD) procedure, followed by silica-based LC quantification. The recoveries ranged from 76.5 to 93.6% with relative standard deviations of 6.0%. (2) Second, the enantiomeric ratio(s) (ER(s)) of the chiral pesticide was (were) determined by LC with a chiral stationary phase after fractionation of the MSPD extract by silica-based LC. The determined ERs or stereoisomeric ratio(s) (SR(s); for propiconazole, only the SR of the 2 diastereomers was determined) in soil samples spiked with the above 8 racemic pesticides agreed with those of the corresponding standard solutions. (3) Third, based on the total concentrations and the corresponding ERs, the concentration of each enantiomer in soil was calculated. The proposed method is rapid, precise, and sensitive, and is appropriate for the investigation of the stereo- and enantioselective degradation of pesticides in environmental media.

Stereo- and enantioselective determination of pesticides in soil by using achiral and chiral liquid chromatography in combination with matrix solid-phase dispersion.

Optimization stacking by transient pseudo-isotachophoresis for capillary electrophoresis: example analysis of plasma glutathione.

A polymer-based monolithic capillary column imprinted with 4-aminopyridine (4-AP) was prepared by a thermally-initiated polymerization process; and its performance as a capillary electrochromatographic medium was evaluated in separating 4-AP and 2-AP isomers. The effects of experimental parameters, such as pH value and ionic strength of the buffer, the acetonitrile content in the mobile phase, and the applied voltage, on the resolution of these isomers had been carefully investigated. It was found that in the retention process there were interplays of multiple mechanisms of ion-exchange, molecular imprinting, and electrophoresis. These mechanisms allowed more sophisticated control of experimental parameters in the separation of ionizable compounds.

Zhichao Zhang

Papers

Fast and precise determination of phenthoate and its enantiomeric ratio in soil by the matrix solid-phase dispersion method and liquid chromatography.

Separation of peptides by pressurized capillary electrochromatography

Stereo- and enantioselective determination of pesticides in soil by using achiral and chiral liquid chromatography in combination with matrix solid-phase dispersion.

Optimization stacking by transient pseudo-isotachophoresis for capillary electrophoresis: example analysis of plasma glutathione.

Capillary electrochromatographic separation of ionizable compounds with a molecular imprinted monolithic cationic exchange column