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To develop a convenient method for sensitive and selective determination of Ce3+ in aqueous phase with complicated matrices, a carbon paste electrode (CPE) modified with ion imprinted polymers (IIPs) were fabricated. The polymers were prepared by precipitation polymerization using Ce3+ as template, allyl phenoxyacetate (APA) as monomer, ethylene glycol dimethacrylate (EGDMA) as crosslinker and azobisisobutyronitrile (AIBN) as initiator under the molar ratio of Ce3+, APA and EGDMA as 1:4:40, respectively. Ce3+ was detected directly by differential pulse adsorptive stripping voltammetry (DPASV) and its oxidation peak appears at about 0.93 V. All parameters affecting the sensor's response are optimized and a calibration curve is plotted at a linear range of 1.0 × 10−6–1.0 × 10−5 mol/L and 1.0 × 10−5–2.0 × 10−4 mol/L with the detection limit of 1.5 × 10−7 mol/L. All other rare earth ions have no interference with the determination of Ce3+ even at a concentration 500 times higher than that of Ce3+. This sensor was successfully applied to determination of Ce3+ in two catalyst sample solutions with RSD≤3.3% (n = 5) and recoveries in the range of 99.2%–106.5% at our optimal conditions.

To solve the problem that the ion-imprinted membrane modified on glassy carbon electrode (GCE) usually easily falls off, a screen printed electrode (SPE) which has a relative rough surface than GCE, was selected as the base electrode for preparation of an ion-imprinted sensor for determination of Eu(III). The sensor was obtained by modifying SPE successively with carboxylic multiwalled carbon nanotubes (MWCNs-COOH) as signal amplifying element and Eu(III) ion-imprinted membrane (Eu(III)-IIM) as specific recognition material. To avoid damaging SPE by thermal initiation, the Eu(III)-IIM was prepared via radical photopolymerization at 380 nm using azobisisobutyronitrile (AIBN) as initiator. Differential pulse adsorptive stripping voltammetry (DPASV) was used for determination of Eu3+ by the obtained sensor. After the detection condition was optimized in detail, the sensor showed a linear response to Eu3+ in the concentration range of 1.0 × 10−7–1.0 × 10−3 mol L−1 with the detection limit of 4.0 × 10−8 mol L−1. The obtained sensor possesses of good regeneration, stability and practicability, it can maintain more than 95% of its original response after used more than 30 times or stored in the water for two months. The satisfactory results with the relative standard deviation (RSD) of less than 3.5% (n = 5) were obtained for the determination of europium in water samples by the novel sensor.

As a result of the increasing applications in different fields, europium has become a threat to the environment and human health. Thus, it is necessary to develop a simple and rapid method for determination of europium in trace level. In this paper, a sensor for determination of Eu3+ was established by modifying a screen printed electrode (SPE) successively with poly catechol as signal amplifying element and Eu(III) ion-imprinted membrane fabricated by sol-gel method as the recognition material. After the factors influenced the sensitivity of the sensor for Eu3+ was optimized in detail, Eu3+ can be determined by differential pulse adsorptive stripping voltammetry (DPASV) in the concentration range of 3.0 × 10−7–1.0 × 10−3 mol L−1 with the detection limit of 1.0 × 10−7 mol L−1. The fabricated sensor owns outstanding selectivity, perfect stability and good regeneration. 50-fold excess concentration of rare earth ions such as Ce3+, Tb3+, Ho3+, Dy3+, Er3+, Gd3+, Pr3+, Nd3+, Yb3+ and 100-fold excess concentration of other metal ions such as Fe3+, Ni3+, Cu2+, Zn2+ and Co2+ have no influence on the determination of 1.0 × 10−5 mol L−1 Eu3+. The obtained sensor, which can maintain >90% of its original response after used >60 times or stored in the water for 2 months, has been satisfactorily used to detect Eu3+ in water samples with the relative standard deviation (RSD) of

In this study, a molecularly imprinted electrochemical sensor based on graphene/Au nanoparticles (G@AuNPs) compound materials and molecularly imprinted membrane (MIM) modified glassy carbon electrodes (GCEs) was developed for the sensitive detection of colchicine in pharmaceuticals and serum (MIM/G@AuNPs/GCE). The film was formed by the in situ polymerization of colchicine-imprinted membranes on the G@AuNPs-modified GCE using methacrylic acid as the functional monomer. The specific surface area, catalytic performance, and electrical conductivity of the electrode increased on account of the formation of G@AuNPs compound materials, thereby improving the sensitivity of the sensor. The MIM as a preconcentrator exhibited chemical selectivity. Under optimal conditions, the MIM/G@AuNPs/GCE sensor exhibited high selectivity and high anti-interference ability. Moreover, good linearity was obtained in the range of 1.2 × 10−8 to 1.2 × 10−6 mol L−1 and 1.2 × 10−6 to 1.0 × 10−4 mol L−1 of colchicine with a detection limit of 4.8 × 10−9 mol L−1. The sensor was successfully applied for the direct determination of colchicine in colchicine tablets and human serum samples, with a relative standard deviation of less than 3.1% (n = 5) and recoveries ranging from 97.5% to 110.0%.

For the aim to detect Ce(III) in food with selectivity, sensitivity and speediness, a electrochemical sensor (Ce(III)-IIM/PC/GCE) was constructed by electropolymerization of a poly-catechol (PC) film on glassy carbon electrode (GCE) followed by modifying a Ce(III) ion-imprinted membrane (IIM) formed with electropolymerization using o-phenylenediamine as monomer. After that, a differential pulse adsorptive stripping voltammetry (DPASV) was developed for determination of Ce(III) by the obtained sensor. Under the optimal conditions, the sensor possesses good reproducibility and storage stability. Furthermore, it can be used directly for determination of Ce(III) in the concentration range of 3.0 × 10− 12–1.0 × 10− 4 mol L− 1 with the limit of detection of 1.0 × 10− 12 mol L− 1. Since over 50-fold excess concentration of Fe3 +, Cu2 + and Ni2 + will produce some interferences in the direct determination of Ce(III), an extraction method was adopted when it be used in food. After extraction of the samples with 1-phenyl-3-methyl-4-benzoyl-5-benzopyrazolone (PMBP), Ce(III) can be determined by Ce(III)-IIM/PC/GCE in the presence of > 500-fold excess concentration of Fe3 +, Cu2 + and Ni2 + with the limit of detection of 4.7 × 10− 9 mol L− 1. The sensor was successfully applied to determine cerium in food after extracted by PMBP with a relative standard deviation (RSD) of

In this study, Fe3O4@PDA@MnO2 core-shell magnetic nanocomposites were synthesized for the first time, and used to enrich target analyte to construct an electrochemical sensor for sensitive detection of trace Pb(II) in the environmental samples. A dense polydopamine (PDA) coating was firstly formed on the surface of Fe3O4 to ensure high stability because the developed method is employed under strongly acidic conditions. Then a high adsorption capacity MnO2 shell can be simply introduced to the surface of the PDA as a result of the redox activity between PDA and KMnO4. Differential pulse voltammetry (DPV) was applied for determining target metal ions. Chemical and electrochemical factors, including quantity of Fe3O4@PDA@MnO2 nanocomposites, preconcentration solutions pH, preconcentration time and supporting electrolytes, were optimized. Under excellent conditions, the designed sensor demonstrated a linear response to Pb(II) within the range of 0.1–150 μg L−1 and with a detection limit of 0.03 μg L−1. The proposed methodology exhibited excellent performance in selectivity, sensitivity and long-term stability, and was also successfully applied to determine Pb(II) in the real water samples. This study suggested that Fe3O4@PDA@MnO2 nanocomposites are a better alternative to Pb(II) analysis resulting from its low cost, low toxicity, strong adsorption, and good reproducibility.

An electrochemical sensor for podophyllotoxin (PPT) based on the molecular imprinting polymer (MIP) membranes was constructed. The sensor was prepared by electropolymerizing o-phenylenediamine (o-PD) on a glassy carbon electrode (GCE) in the presence of PPT as template, and then removing the template by immersing the modified GCE in ethanol. Experimental parameters such as the types of monomer, scan cycles, concentration of o-PD and extraction condition were optimized. Under optimal conditions, the sensor exhibits a good selectivity and high sensitivity. A good linearity was obtained in the range of 4 x 10-8 mol · L(-1) to 3.2 x 10(-5) mol · L(-1) with an estimated detection limit of 4.8 x 10(-9) mol · L(-1). The sensor was applied to the determination of PPT in podophyllum hexandrum and human serum samples with satisfactory results.

To develop a rapid and simple method for sensitive determination of artemisinin (ART) in complicated matrices, a novel electrochemical sensor was constructed by in-situ polymerization of ART-imprinted membranes (ART-MIMs) on the surface of graphene (G) modified glassy carbon electrode (GCE) using acrylamide (AM) as functional monomer, ethylene glycol dimethacrylate (EGDMA) as cross-linking agent after the experimental parameters for the preparation of ART-MIMs such as functional monomer, molar ratio of template, monomer and cross-linking agent together with extraction condition were optimized. Under the optimal conditions, the sensor named as ART-MIM/G/GCE exhibited a good selectivity, high sensitivity and considerably better resistance against some analogs of artemisinin such as dihydroartemisinin (DHA), artemether (ARM) and artesunate (ARTS). The calibration graph for the determination of artemisinin by the sensor was linear in the range of 1.0 × 10(-8)mol L(-1) to 4.0 × 10(-5)mol L(-1) with the detection limit of 2.0 × 10(-9)mol L(-1). Meanwhile, this sensor possessed of good regeneration, stability and practicability. It could retain more than 94% of its original response after used at least 80 times or stored in water at room temperature for 60 days. The obtained sensor was successfully applied to determine the contents of artemisinin in the extract of Artemisia annua L. with the relative standard deviation (RSD) of less than 3.5% (n=5).

To develop a convenient method for sensitive and selective determination of platinum in complicated matrices, an ion-imprinted electrode was studied by in situ polymerization of Pt(IV) ion-imprinted membranes (Pt(IV)-IIMs) on the surface of a glassy carbon electrode (GCE). After the experimental parameters for the preparation of Pt(IV)-IIMs such as functional monomer, molar ratio of template, monomer and cross-linking agent together with extraction condition were optimized, an electrode with good regeneration, high stability and specific recognition to Pt(IV) was obtained by modifying GCE with Pt(IV)-IIMs prepared in acetonitrile using allylurea (NAU) as functional monomer, ethylene glycol dimethacrylate (EGDMA) as cross-linking agent, azobisisobutyronitrile (AIBN) as initiator under the molar ratio of template (H2PtCl6), NAU and EGDMA as 1 : 4 : 40. The resulting electrode named as Pt(IV)-IIMs/GCE exhibits high response sensitivity to Pt(IV) in phosphate buffer (pH 5.29). The calibration graph for the determination of Pt(IV) by Pt(IV)-IIMs/GCE is linear in the range of 2.0 × 10−8 ∼ 2.5 × 10−4 mol L−1 with a detection limit of 4.0 × 10−9 mol L−1. No metal ions tested at a concentration 25 times higher than that of Pt(IV) interfered in the determination. The electrode was successfully applied to determine platinum in catalyst and plant samples with a relative standard deviation (RSD) of less than 3.0% (n = 5) and recoveries in the range of 97.8–103.6%.

A novel strategy for the preparation of amperometric immunosensor for rapid determination of α-1-fetoprotein (AFP) in human serum has been developed. TiO 2 nanoparticles (NPs) were prepared by solvothermal reaction using TiCl 4 as raw materials and the mixture of ionic liquids and doubly distilled water as solvent. α-1-fetoprotein antibody (AFP Ab) was mixed with TiO 2 NPs/chitsotan (CHIT) solution and immobilized onto the surface of a glassy carbon electrode. AFP (Ab) functionalized Au NPs were used as catalytic labels for the amperometric detection of AFP by means of the electrocatalyzed reduction of Au NPs to H 2 O 2 . The electrochemical behavior of the immunosensor was studied. Other experimental conditions such as pH, immunoreactions temperature and time were also studied. The prepared immunosensor offers an excellent amperometric response for AFP ranging from 1.0 to 160.0 ng/mL with a detection limit of 0.1 ng/mL. The result shows that the immunosensor displays rapid response, high sensitivity, good reproducibility and favorable stability.

Gold nanoelectrode ensembles were produced by electrodeposition using multiwalled carbon nanotubes (MWNTs) as template. A new third generation amperometric biosensor for hydrogen peroxide was developed based on adsorption of horseradish peroxidase (HRP) at the glassy carbon (GC) electrode modified with Au nanoelectrode ensembles/multiwalled carbon nanotubes/chitosan film. The resulting HRP biosensor offered an excellent detection for hydrogen peroxide at −0.11 V with a linear response range of 2.08 × 10−7 to 7.6 × 10−3 M with a correlation coefficient of 0.998, and response time

Gold nanowires were produced by electrodeposition in polycarbonate membrane, with an average diameter of 200 nm and a height of about 2 μm. The nanowire array prepared by the proposed method can be considered as nanoelectrode ensembles (NEEs). An amperometric pesticides sensor based on gold NEEs has been developed and used for determination of phoxim and dimethoate in vegetable samples. The electrochemical performance of the gold NEEs has also been studied by the amperometric method. The electrode provided a linear response over a concentration range of 5.9 × 10−5 to 1.2 × 10−2 M for phoxim with a detection limit of 4.8 × 10−6 M and 6.3 × 10−5 to 1.1 × 10−2 M for dimethoate. This sensor displayed high sensitivity and selectivity, long-term stability and wide linear range. In addition, the ellipsis of enzyme and the reactivation of enzyme make the operation simple. This sensor has been used to determine pesticides in a real vegetable sample.

A Novel Carbon Paste Electrode Based on Ion-Imprinted Polymer for Determination of Iridium To develop a convenient method for sensitive and selective determination of iridium in complicated matrices, a carbon paste electrode based on iridium ion imprinted polymer (IIP) was fabricated. Iridium ion selective cavities were created in the 2-(allylthiol) nicotinic acid based cross-linked polymer. In order to fabricate the sensor, carbon particles and polymer powder were mixed with melted n-eicosane. An explicit difference in the response was observed between the electrodes modified with ion imprinted polymer (IIP) and non imprinted polymer (NIP), indicating proper performance of the recognition sites of the IIP. Various factors, known to affect the response behavior of selective electrode, were investigated and optimized. The resulting sensor named as Ir(III) ion imprinted polymer carbon paste electrode (Ir(III)-IIP/CPE) exhibits high response sensitivity to Ir(III) in acetate buffer (pH 3.6). The calibration graph is linear in the range of 2.85×10-8∼2.31×10-5 mol L-1 with the detection limit of 7.84×10-9 mol L-1(S/N). The electrode showed high selectivity for iridium in the presence of common potential interferers was found to show satisfactory results, it was successfully applied to the determination of iridium in real samples.