Separation and measurement of eruption by SPME (Solid Phase Microextraction) method using molecular template polymer

Master's thesis in the field of chemistry

Analytical chemistry trend

Abstract

In this polymer project, a molecular template was prepared for the selective extraction of furan. To prepare this polymer, methacrylic acid (functional monomer), ethylene glycol dimethacrylate (cross-linking agent), 2,2-azobisisobutyronitrile (initiator), a mixture of pyrrole (furan substitute or target molecule) and methanol (solvent) were used. Polymerization raw materials are placed in capillary tubes. After applying the heat treatment, the capillary tube is finally thrown into the hydrofluoric acid so that the glass is eaten and the fiber comes out. The result of radical polymerization is the formation of non-covalent molecular template polymer (MIP) tubular fiber. Due to the presence of non-covalent interactions between the target molecule and the functional monomer, the target molecule is removed by washing and the molded polymer is obtained.

In order to compare the efficiency of this polymer, another polymer was also made with the same method and the same raw materials (NIP, the observer polymer), with the only difference that the new polymer does not have the target molecule in its structure. The spectra of both synthesized polymers were investigated through FT-IR spectroscopy, both polymers have structural similarities, and the presence of holes in the molecular template polymer can be justified by comparing the two spectra. The synthesized molecular template polymer was compared with the control polymer. The properties of the molecular template polymer, the bond formation ability and the selectivity property of the desired polymer were investigated.  Also, in order to optimize the absorption conditions, various parameters such as pH, absorption time, temperature and salt concentration were investigated.  

Key words: molecular template polymer, furan, pyrrole

Chapter 1: Furan and how it is produced in food and its carcinogenicity

1-1 What is furan?

Foran (C4H4O, CAS No.110-00-9) is a volatile heterocyclic organic chemical that is often found as an intermediate in industrial processes for the production of synthetic polymer materials. Furan is a very diverse group of chemicals sometimes referred to collectively as "furans" and includes antimicrobial toxins (nitrofurans) and various pseudo-dioxins.

Concern about the presence of furan in foods dates back to 2004, when a Food and Drug Administration (FDA) study of heat-processed foods in the United States revealed that small amounts of furan can be found in unexpectedly large proportions in container-processed foods. It was found in containers such as cans and glass containers. Furan is a possible human carcinogen and therefore even small amounts of it in foods are undesirable. 1-2 Formation of furan in food The advancement of food processing technology, which includes frying, roasting, grilling, thickening, smoking, sterilization, pasteurization, irradiation, salting, freezing, canning, and irradiation, increases the capacity of food reserves. It has been greatly developed in the modern era. Cooking increases the desirability (for example, taste, appearance, texture) and stability of foods, and also improves the digestion of foods. In addition, it destroys toxic microorganisms and neutralizes undesirable factors such as inhibiting enzymes. Chemical changes in food compounds include acids. Amino, proteins, sugars, carbohydrates, vitamins and fats by high heat process, added to the frequently asked questions in the field of nutritional value reduction. Even the formation of a number of chemical poisons such as polycyclic aromatic hydrocarbons, acrylamide, amino acids and pyrolyzed protein and furan is seen in food.

Furan is an aromatic heterocyclic compound with an oxygen atom. Very volatile, colorless liquid, flammable

It has been determined that furan is a carcinogenic compound. It has been identified that furan is produced during heating of food by pyrolysis of food components such as vitamin C, carbohydrates, proteins, and polyunsaturated fatty acids and also by the interaction between these compounds. And it has also been suggested that the most effective precursor of furan is ascorbic acid and its derivatives. One of the most probable patterns of furan formation from glucose pyrolysis is given in Figure 1. Among the food products contaminated with furan, glass baby food has received more attention due to the vulnerability of children and infants to toxic substances and in addition to the high daily intake compared to the child's weight.The rest of the foods in which furan formation occurs are vegetables, fruit, canned meat and fish, pasta sauce, nutritional drinks, beers and coffees.

The lowest amount of furan was reported for fruit products (6-16 ppb) and products that only contain meat, rice starch and corn, (3-8 ppb). And the highest amount was found in baby food containing vegetables.

In the case of eruption, at first they thought that this volatile substance comes out of the food as a result of simple evaporation, for example, when a can or glass is opened. But it was proven that this thought is not correct. In fact, the eruption in foods is stable. The amount of eruption that is formed during heating in closed containers during the industrial process does not decrease much when heating and eating the food. Except in the cases of cooking and boiling, it is possible that the eruption is lost by evaporation and a large volume of steam that is released. In other words, heating the food and placing the lid of the containers even partially can raise the eruption level. natural, or through compounds used in food or enriched in this system. There is a proposal in 2004 that the formation of furan from AA can take place under oxidative and non-oxidative conditions.

1-2-2 Validation of the HS-LPME measurement method to determine furan compounds in baby foods:

To ensure the efficiency of the HS-LPME-GC/MS method to perform the desired analysis, review a method It is necessary. Validation criteria of an analytical method are: correctness, accuracy, linearity range, detection limit and measurement limit were checked.

Examination of the curve of classification of explosive compounds in water shows that this curve is linear with a high correlation coefficient (R2>0.99) in the concentration range of 0.2-200?g/L. Examining the results related to the relative standard deviation shows the good accuracy of the method for explosive compounds (7.06-84.3%), the accuracy of the measurement method for explosive compounds is acceptable (64.80-103.83%). The values ??of concentration factor for furan are 972, -2-methylfuran 640 and 2-5-dimethylfuran 503. For this method, it is 0.038-0.021 ng/g, which is less than the detection limit of other analysis methods. The measurement limit obtained for explosive compounds by this method (0.069-0.126 ng/g) is lower than the measurement limit of other methods (1, 2, 11, 15). The comparison of merit figures of the proposed method with two other methods shows that its grading curve is within an acceptable range for measuring explosive compounds and the accuracy, detection limit and measurement limit of the HS-SPME method are better than the other two methods.

Abstract English

In this work a molecular imprinted polymer was synthesized for selective extraction of furan. These imprinted polymers were synthesized by using methacrylic acid (functional monomer), ethylene glycol di-methacrylate (crosslinker), 2, 2-azo bis (2-methylpropionitrile) (initiator), pyrole (alternative furan or target molecules) and methanol (solvent). Polymerization agents are placed in a capillary tube for the preparation of a monolithic polymer. Then the template molecule is removed by a methanolic solution. To compare the performance of these polymers, another polymer was prepared by the same method, only with the absence of template molecule (NIP polymer observer). Synthesized polymers were characterized by FT-IR spectroscopy. Effective parameters in adsorption such as pH, adsorption time, temperature and salt concentration were investigated.  

Keywords: polymer molecular form, furan, pyrrole.