Preparation Of Novel Nanomaterials Modified Polymer Monolith And Its Application In The Detection Of Organic Residues In Food Samples

In recent years, polymer monolith microextraction (PMME) has been widely applied tothe determination of organic residues in food. As a new separation technology, PMME notonly inherits the advantages of easy to operate, solvent-free, short time-consuming,synchronous separation, purification and enrichment for solid-phase microextraction (SPME),also has outstanding features of simple preparation, good permeability, and easymodification.With a relentless probe into the separation field about polymer monolith functionalmodification, nanomaterials have became a good choice in application of modifying monolithdue to their superior surface area and optional surface chemistry features. In this work, In2O3nanoparticles modified polymer monolith and3-trimethoxysilyl propyl methacrylate(γ-MAPS) grafted sodium titanatenanotubes (NaTiNTs) modified monolith were prepared,respectively, which coupled with HPLC and HPLC-MS/MS for the determination of organicresidues in food. The specific experimental study is divided into two parts:1. Poly(methacrylic acid-glycidyl methacrylate-ethylene dimethacrylate) monolithmodified with In2O3nanoparticles and ethylenediamine was prepared and used as theextraction medium coupled to HPLC-MS/MS for detecting12kinds of synthetic colorantsresidues (Acid Red2G, Acid Orange Ⅱ, Acid Yellow36, Azorubine, Patent Blue VF, AcidGreen50, Erythrosine, Allure Red AC, Sunset Yellow FCF, Quinoline Yellow, Rhodamine Band Chrysoidine) in a variety of food samples. In this experiment, API4000tandem massspectrometer (USA, Applied Biosystems) equipped with an Agilent1200LC system wasused for separation and detection of target synthetic colorants. HPLC separation wasperformed on an Agilent Pursuit XRs5-C18HPLC column (2.0100mm,3μm). The flow rate was set at250μL min–1while the column temperature was maintained at roomtemperature. The injection volume was10μL. The mobile phase system consisted of20mmol L–1ammonium acetate (A) and acetonitrile (B). A gradient program was used forelution:0–2.0min,10%B;2.0–14.0min,10%–80%B;14.0–15.0min,80%B;15.0–15.2min,80%–10%B; and15.2–20.0min,10%B.The mass spectrometer was operated under multiple reaction monitor mode (MRM) forquantitative and qualitative analysis in positive and negative ion modes. The optimumconditions of the ESI interface for all target analytes were as follows: curtain gas (nitrogen) at30psi, nebulizer gas GS1and GS2at30psi and30psi, respectively, desolvation temperatureat550°C, collision activated dissociation gas (CAD) at6units of the arbitrary scale of theinstrument, and ion spray voltage (IS) at5500/–4500V. The optimized PMME conditionswere determined as follows: sample pH,4.0; sample flow rate,0.06mL min1; Samplevolume,1.0mL; and eluent flow rate,0.04mL min1. Under the above-mentioned optimumconditions, the PMME-HPLC-MS/MS method was validated with respect to linear range,correlation coefficients (R2), limit of detection (LOD), and limit of quantification (LOQ). Thecalibration curves of the analytes were constructed with linear range of0.5–50μg kg–1,5–200μg kg–1, and10–500μg kg–1, respectively. The12target colorants showed goodlinearity with satisfactory R2values greater than0.9982. LOD and LOQ, based on theconcentration giving the signal-to-noise ratio of3and10, were found in the range of0.012–2.97μg kg–1and0.04–9.9μg kg–1, respectively. The intra-day and inter-day relativestandard deviations (RSD, n=7), determined in one day and in five successive days, wereless than7.6%and8.5%, respectively, indicating a high precision of this method. Therecoveries with different levels were73.5112.1%when applied to a variety of food samples.2. γ-MAPS grafted NaTiNTs nanotubes chemically modified poly(methacrylicacid-ethylene dimethacrylate) monolith was synthesized. The PMME-HPLC-DAD methodwas established to detection for eight sulfonamides (Sulfadiazine (SDZ), sulfapyridine (SPD),sulfamerazine (SMR), sulfamethoxypyridazine (SMP), sulfachlorpyridazine (SCP),sulfadoxine (SDX), sulfafurazole (SIZ), and sulfadimethoxine (SDM)) residues in honeysamples. Several experimental parameters affecting the extraction efficiency wereinvestigated by single-factor experiments firstly, such as sample pH, sample flow rate, samplevolume, eluent flow rate, and eluent type. The first four factors were then further evaluated by means of a Taguchi’s L9(34) orthogonal array experimental design. Under the optimizedconditions, the limits of detection (S/N=3) and limits of quantitation (S/N=10) were in therange of0.681.42and2.284.72μg kg–1, respectively. The intra-day and inter-day relativestandard deviations were determined to be from1.9%to6.9%. The recoveries of targets atdifferent spiked levels ranged from80.3%to109.9%with relative standard deviations lessthan9.5%.