Electronic Supplementary Material (ESM)

Determination of methamphetamine, amphetamine and ecstasy by inside-needle adsorption trap based on molecularly imprinted polymer followed by GC-FID determination

Djavanshir Djozan1*, Mir Ali Farajzadeh1, Saeed Mohammad Sorouraddin1, Tahmineh Baheri2

1 Laboratory of Chromatography, Faculty of Chemistry, University of Tabriz, Tabriz, Iran

2 The Research Center of Antinarcotics Police, Tehran, Iran

* Corresponding author, Email: , Tel.: +984113393084, Fax: +984113340191

Effect of treatment of the internal surface of the needle on the extraction capability

Previous papers [1,2] showed that coating of MIP layer on the surface of oxidized and silylated stainless steel resulted in a satisfactory analytical signal. The immersion of the stainless steel extraction needle in an oxidant solution gives rise to hydroxyl groups on the surface of the needle which can react with methoxy groups of TMPM [1-4]. The silylated extraction needle could be participated in the co-polymerization of MIP bulk and could form a firm MIP coating layer. Therefore, internal surface was oxidized and then silylated as described previously [1] and the results showed that by oxidizing and silylating stainless steel in the optimum conditions, the average peak areas of MAMP increased from 13053(±792) to 28731 (±991).

Fig. S1 The effect of nature and level of porogens on the extraction effeciency of MAMP, AMP and MDMA by MAMP- MIP coated extraction needle. The concentration of model solution and volume were 500 ng mL−1and 5 mL, respectively. The bars indicate the maximum and minimum of three extractions and determinations.

Optimization of template to MIP components ratio at various temperatures

For this purpose, various types of extraction needles were fabricated in the presence of different amounts of MAMP (1.5–2.1 mmol) during 10 h at various polymerization temperatures. They were used for the extraction of the analytes from 5 mL of the aqueous model solution under identical conditions. The variation of the extraction efficiency of the analytes versus template amount at various polymerization temperatures are shown in Fig. S2. The results revealed that 1.7 mmol was the optimum amount of template which was also independent of the polymerization temperature. By considering these results and the previously reported ones [1], it can be concluded that the amount of template is dependent on the nature of template (for the present MIP components). The results were also revealed that 55°C was the optimum polymerization temperature.

Fig S2. The effect of template amount and temperature of polymerization reaction on the efficiency of the fabricated MAMP-MIP needle. Duration of polymerization, 10 h; porogen solvent, acetonitrile (30 mL). The bars indicate the maximum and minimum of three extractions and determinations.

Investigation of chemical and thermal stability

Chemical stability of the fabricated extraction needles is another important factor to be considered, since it is indispensable in carrying out the extraction from acidic or basic aqueous samples and organic solvents. To achieve this, four MAMP-MIP coated needles were fabricated. First, each needle was used for three repetitive extractions and desorptions of the analytes from the model solutions. They were then filled by chloroform, methanol, and aqueous solutions of 1 M HCl and 1 M NaOH separately for 24 h at 25 °C. Afterwards, the needles were washed with doubly distilled water and were again used for three repetitive extractions and desorptions of the analytes from model solutions. Considerable variations in the extraction behavior of the fabricated needles were not observed. Therefore, it can be concluded that the fabricated needles were chemically stable. Since the MIP-coated needles would be introduced into GC injector port for thermal desorption of analytes, the thermal stability of the fabricated needles is quite important. The needles were introduced into the GC injection port at different temperatures ranging from 240 to 320 °C for 5 min and under helium gas flow. Then, they were used for extraction of the analytes from aqueous model solutions in the optimum conditions. The extracted amounts were monitored by GC analysis and it was revealed that the extraction ability of the fabricated needles did not change until 300 °C which can be regarded as the limiting temperature of application for these extraction needles. At higher temperatures, thermal decomposition gently took place and extraction ability was altered.

References:

[1] Djozan Dj, Farajzadeh MA, Sorouraddin SM, Baheri T, Norouzi J (2012) Development of an inside needle extraction method based on molecularly imprinted polymer for solid-phase dynamic extraction and preconcentration of triazine herbicides followed by GC–FID determination. Chromatographia 75:139-148.

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[4] Schweitz L, Andersson LI, Nilsson S (1997) Capillary electrochromatography with molecular imprint based selectivity for enantiomer separation of local anaesthetics. J Chromatogr A 792:401–409.