Highly selective separation and detection of cyromazine from seawater using graphene oxide based molecularly imprinted solid-phase extraction

A novel molecularly imprinted polymer based on graphene oxide was prepared as a solid-phase extraction adsorbent for the selective adsorption and extraction of cyromazine from seawater samples. The obtained graphene oxide molecularly imprinted polymer and non-imprinted polymer were nanoparticles and characterized by scanning electron microscopy. The imprinted polymer showed higher adsorption capacity and better selectivity than non-imprinted polymer, and the maximum adsorption capacity was 14.5 mg/g. The optimal washing and elution solvents for molecularly imprinted solid phase extraction procedure were 2 mL of acetonitrile/water (80:20, v/v) and methanol/acetic acid (70:30, v/v), respectively. The recoveries of cyromazine in the spiked seawater samples were in the range of 90.3-104.1%, and the relative standard deviation was <5% (n = 3) under the optimal procedure and detection conditions. The limit of detection of the proposed method was 0.7 μg/L, and the limit of quantitation was 2.3 μg/L. Moreover, the imprinted polymer could keep high adsorption capacity for cyromazine after being reused six times at least. Finally, the synthesized graphene oxide molecularly imprinted polymer was successfully used as a satisfied sorbent for high selectivity separation and detection of cyromazine from seawater coupled with high-performance liquid chromatography.

Cyromazine imprinted polymers for selective stir bar sorptive extraction of melamine in animal feed and milk samples

A molecularly imprinted polymer coated stir bar was prepared using a self-designed polytetrafluoroethylene mold andin situpolymerization, with cyromazine as dummy template for target melamine.

Molecular imprinting science and technology: a survey of the literature for the years 2004-2011

Herein, we present a survey of the literature covering the development of molecular imprinting science and technology over the years 2004-2011. In total, 3779 references to the original papers, reviews, edited volumes and monographs from this period are included, along with recently identified uncited materials from prior to 2004, which were omitted in the first instalment of this series covering the years 1930-2003. In the presentation of the assembled references, a section presenting reviews and monographs covering the area is followed by sections describing fundamental aspects of molecular imprinting including the development of novel polymer formats. Thereafter, literature describing efforts to apply these polymeric materials to a range of application areas is presented. Current trends and areas of rapid development are discussed.

Comparison of three methods for detection of melamine in compost and soil

Recent product recalls and food safety incidents due to melamine (MM) adulteration or contamination have caused a worldwide food security concern. This has led to many methods being developed to detect MM in foods, but few methods haves been reported that can rapidly and reliably measure MM in environmental samples. To meet this need, a high performance liquid chromatography (HPLC) with UV detection method, an enzyme-linked immunosorbent assay (ELISA) test kit, and an enzyme-linked rapid colorimetric assay (RCA) test kit were evaluated for their ability to accurately measure MM concentrations in compost and soil samples. All three methods accurately detected MM concentrations if no MM degradation products, such as ammeline (AMN), ammelide (AMD) and cyanuric acid (CA), were present in an aqueous sample. In the presence of these MM degradation products, the HPLC yielded more accurate concentrations than the ELISA method and there was no significant (P>0.05) difference between the HPLC and RCA methods. However, if samples were purified by SPE or prepared with blocking buffer, the ELISA method accurately measured MM concentrations, even in the presence of the MM degradation products. The HPLC method generally outperformed the RCA method for measuring MM in soil extracts but gave similar results for compost extracts. The number of samples that can be analyzed by the ELISA and RCA methods in a 24-hour time period is much greater than by the HPLC method. Thus the RCA method would seem to be a good screening method for measuring MM in compost and soil samples and the results obtained could then be confirmed by the HPLC method. The HPLC method, however, also allows simultaneous measurement of MM and its degradation products of AMD, AMN and CA.

Molecularly imprinted polymers in drug delivery: state of art and future perspectives

INTRODUCTION

Molecularly imprinted polymers (MIPs) are synthetic receptors, characterized by a high selectivity for the selected template. Among the different applications of MIPs, their use as controlled/sustained drug delivery devices has been extensively explored, even though the optimization of such devices needs to be performed before they are applied in clinical practice.

AREAS COVERED

Within drug delivery, one of the most promising fields is the possibility to modulate the drug release profile in response to a specific external stimulus; MIPs represent potentially suitable vehicles, because of the possibility to insert a stimuli-responsive co-monomer in their structure. This review discusses recent advances in the use of external stimuli to modulate drug release, as well as the synthetic strategies devoted to increase the water compatibility of these systems, which is a base requirement for their application in biomedicine.

EXPERT OPINION

Although it is easy to imagine imprinted polymers for biomedical applications, several aspects have to be further investigated, such as the in vivo studies, efficiency and biocompatibility. However, we think that in the next few years it will possible to see unprecedented progress in the preparation of such systems and the translational application of these intelligent structures in medicine.

Molecularly-imprinted microspheres for selective extraction and determination of melamine in milk and feed using gas chromatography-mass spectrometry

Molecularly-imprinted polymers in the form of microspheres were synthesized using the dispersion polymerization protocol; cyromazine was used as dummy template, while methacrylic acid, ethylene glycol dimethacrylate and acetonitrile (MeCN) were used as functional monomer, cross-linker, and porogen, respectively. When compared with the non-imprinted polymer, the molecularly-imprinted polymers (MIPs) showed outstanding affinity toward melamine in MeCN with a maximum binding concentration (B(max)) of 53.20 nmol mg(-1) MIPs, imprinting effect of 4.6, and a dissociation constant (K(d)) of 90.45 microM. After optimization of the molecularly-imprinted solid-phase extraction conditions, a new method was developed to determine the melamine in milk and feed with gas chromatography-mass spectrometry. The performance of this method has been evaluated in the tainted milk and feed in terms of recovery, precision, linearity, the limit of detection (LOD) and limit of quantitation (LOQ). Recovery ranged in samples from 93.1 to 101.3% with intra-day and inter-day relative standard deviation values below 5.34%. The LOD and LOQ of melamine in milk and feed were 0.01 microg mL(-1) (microg g(-1)) and 0.05 microg mL(-1) (microg g(-1)), respectively.