I am following method but washing carried out in centrifuge instred of soxclet
Synthesis of the M-MIP was performed in four steps: preparation of
magnetic nanoparticles (Fe3O4), modification with TEOS, silanization
with MPS, and preparation of the M-MIP.
The procedures used for
the synthesis of the M-MIP selective to tetracycline were based on the protocol
described by Lu et al. [24], but with some modifications to improve
the synthesis. An M-NIP was also synthesized as a control material.
In the first stage, the magnetic nanoparticles were synthesized by the
co-precipitation method, starting from the iron precursor salts, using a
sodium hydroxide solution as a precipitating agent, under anaerobic
conditions (nitrogen atmosphere) at room temperature, following a
procedure well established in our laboratory [17,18,20]. For this, 1.6 �
10 2 mol FeCl3⋅6H2O and 7.8 � 10 3 mol FeCl2⋅4H2O were solubilized
in 40 mL of H2O, under an inert atmosphere and with constant agitation.
The solubilized salts were mixed in a flask equipped with a mechanical
stirrer, pH meter, and nitrogen feeder. The connections of the equipment
were kept closed, in order to maintain an inert nitrogen environment.
Rapid addition was made of NaOH (1.5 mol L 1), until reaching pH 10
(approximately 50 mL), under constant agitation, with the appearance
of a black precipitate corresponding to the formation of magnetite
immediately after the addition of the aqueous solution of sodium hydroxide.
The nucleation and growth of the magnetic particles occurred during 40
min, with constant stirring under an inert atmosphere. Finally, a magnet
was used to completely separate the black solid from the solution, followed
by washing and drying at room temperature (Scheme 1).
The second step was modification of the magnetite with TEOS to
obtain the Fe3O4@SiO2. First, 300 mg of magnetic nanoparticles were
mixed with 4 mL of water, 40 mL of ethanol, and 5 mL of aqueous
ammonia. This dispersion was then homogenized by ultrasonication in a
water bath. Finally, TEOS was slowly added to the dispersion, undercontinuous mechanical stirring, and after stirring for 12 h, the silica was
formed on the surfaces of the magnetite nanoparticles by hydrolysis and
condensation of TEOS. The product formed was washed with deionized
H2O and dried at room temperature.
The third step was silanization of the product obtained in the previous
step. For this, 250 mg of Fe3O4@SiO2 were weighed out and
dispersed in a mixture of 45 mL of toluene and 5 mL of MPS, under a
nitrogen atmosphere, for 12 h. The material was then washed using
ethanol and H2O, followed by drying at room temperature.
The last step in the preparation of the M-MIP was mixing of the
analyte, monomer, and crosslinking reagent at a ratio of 1:12:120. For
this, 2.5 � 10 4 mol of tetracycline and 3.0 � 10 3 mol of functional
monomer (methacrylic acid or acrylic acid) were reacted in 50 mL of
methanol/ethanol (1:1, v/v), under an anaerobic atmosphere (N2),
maintaining the mixture at a temperature of 25 �C for 24 h to ensure that
all the functional monomer interacted with the analyte. Next, 100 mg of
the modified magnetic nanoparticles obtained in the third stage
(Fe3O4@SiO2-MPS) were added, with stirring for 3 h. Addition was then
made of 3.0 � 10 2 mol EGDMA (crosslinking reagent) and 2.5 � 10 4
mol benzoyl peroxide (radical initiator), with mixing and heating at a
temperature of 87 � 4 �C, under a nitrogen atmosphere (since oxygen
could inhibit the polymerization). It is important to highlight that to the
best of our knowledge, this is the first time that benzoyl peroxide has
been used to obtain an M-MIP selective to tetracycline.
After the polymerization process, a washing step was essential for
elimination of the analyte [25]. In addition, the excess of monomer and
possible impurities present in the reaction medium were also removed.
Finally, the template was removed using a Soxhlet system with a solution
of methanol and acetic acid (9:1, v/v), as well as with methanol
Dear Syed Asim Hussain Shah thank you for this interesting technical question. In the literature procedure it is stated that "the template was removed using a Soxhlet system with a solution of methanol and acetic acid (9:1, v/v), as well as with methanol". I think this should not be modified but followed in all detail. Soxhlet extraction is much more effective in thoroughly removing side products than simple washing or centrifugation. Thus I suggest that you ask organic chemistry colleagues if you could borrow a Soxhlet apparatus from them. For more general information on Soxhlet extraction please see the respective Wikipedia entry at
https://en.wikipedia.org/wiki/Soxhlet_extractor
Please also have a look at the following potentially useful articles entitled
Synthesis of Magnetic Molecularly Imprinted Polymer Sorbents for Isolation of Parabens from Breast Milk
(see attached)
and
Synthesis and characterization of the core-shell magnetic molecularly imprinted polymers (Fe3O4@MIPs) adsorbents for effective extraction and determination of sulfonamides in the poultry feed
Article Synthesis and characterization of the core-shell magnetic mo...
Thank you very much @frank actually I am.not sure why polymerzation between nanoparticles and MIp not occur..I am.quite stuck with this as I repeat the experiments three time but got the same result ..
You are doing radical polymerization, so, a tiny amount of dissolved O2 can stop the reaction. Hence, I do recommend precise N2 or Ar purging of the reaction medium before and after addition of the initiator and continuing the reaction under an inert atmosphere. It's a bit tricky to do reaction under complete inert atmosphere. Also, slightly increase the initiator amount.
It would nice if you could share the result of your attempts in this regards.
- Badges
- Science topic
- Similar topics
- Chemistry
- Sulfites
- Inorganic Chemistry
- Inorganic Chemicals
- Salts