Atrazine-imprinted membranes

PTT.F.TSKY S A, PILETSKAYA E V, ELGERSMA A V, YANO K and KARUBE I (1995), Atrazine sensing by molecularly imprinted membranes , Biosens Bioelectro, 10, 959-964. 

Using diethyl aminoethylmethacrylate and ethylene glycol dimethacrylate, atrazine selective membranes were produced and incorporated into an atrazine sensor [125]. Atrazine could be detected over the range 0.01-0.50 mg/L with a response time of 30 mins and, most importantly, the sensors did not show loss of sensitivity over a four month period. Selective membrane diffusion of adenosine over guanosine was achieved using a membrane imprinted with 9-ethyladenine [126] and other selective membranes have also been prepared [127,128],... 

Sergeyeva TA, Piletsky SA, Brovko AA, Slinchenko EA, Sergeeva LM, El skaya AV. Selective recognition of atrazine by molecularly imprinted polymer membranes. Development of conductometric sensor for herbicides detection. Anal Chim Acta 1999 392 105-111. 

In Piletsky s latest work, free-standing membranes are formed by polymerisation between two glass slides, with oligourethane acrylate being incorporated in the polymer mixture to lend extra flexibility [94,95]. Using atrazine again as the imprinted species, a detection limit for atrazine of 5 nM and 20-fold selectivity over simazine are reported. 

With regard to substrate-selective sensors with pre-organized cavities, impressive advances have been made in molecular imprinting [55-57]. The discovery of MIP-membrane electro conductivity was an interesting issue, which actually led to the appearance of the earliest MIP sensors [58,59]. It was shown that the membrane electroconductivity could be a function of the interaction between MIP-membrane and ligand (i.e., imprint species) (Fig. 5). An increase in the ligand concentration would result in an enhancement of membrane conductivity. With the same level of concentration, a maximal electro conductivity with the imprint species could be achieved. In addition, it has also been confirmed that polymers imprinted with amino acids, nucleosides, atrazines, sialic acids, or cholesterols can show similar features if coupled with the appropriate transducer [60-64], In particular, molecular imprinting is presently probably the only choice when no suit-... 

Investigations of conductivity of MIP membranes—separating two cells filled with electrolyte—had led to the first MIP membrane sensor [1,96] an increase of template concentration in the solution caused a change (mostly an increase) of membrane conductivity. The magnitude of the effect was much higher for substances with the same or very similar structure as compared with the template. Hence, sensor membranes imprinted with L-Phe, atrazine, or cholesterol all showed pronounced selectivity and a sensitivity in the micromolar range. Another important observation, made by UV -Vis spectroscopic analysis in the two cells, was that the addition of template (here atrazin) increased the permeation rate of another substance (here -nitrophenol) through the MIP membrane [1,97]. 

Sergeyeva, T.A Piletsky, S.A. Brovko, A.A. Slinchenko, L.A. Sergeeva, L.M. Panasyuk, T.L. El skaya, A.V. Conductometric sensor for atrazine detection based on molecularly imprinted polymer membrane. Analyst. 1999,124, 331-334. 

Imprinted polymer membranes are prepared using atrazine as the template, methacrylic acid as a functional monomer, and tri(ethylene glycol) dimethacrylate (TEDMA) as a cross-linker. The molar ratio of the functional monomer to the template is 5 1. This ratio has to be optimized for each template. In order to obtain thin, flexible and mechanically stable membranes, oligourethane acrylate (molecular mass 2600) is added to the monomer mixture. Preparation of the molecularly imprinted polymer membrane is done as follows. Atrazine (20 mg) is mixed with methacrylic acid (40 mg), TEDMA (289 mg), oligourethane acrylate (51 mg), AIBN (2 mg) and 30% v/v of chloroform. Then a 60-120 pm gap between two quartz slides is filled with the monomer mixture. To initiate polymerization, the slides with the mixture are exposed to UV radiation (365 nm, intensity 20 W m ) for 30 min. After polymerization, atrazine is extracted with ethanol in a Soxhlet apparatus for 2h. This should not cause any visible changes in the MIP membrane. A membrane for control experiments can be prepared similarly except that no atrazine is added to the monomer mixture. 

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