Capillary liquid chromatography with diode array and mass spectrometry detection for heterocyclic aromatic amine determination in ready-to-eat food treated with electron-beam irradiation.

In the present paper, we have developed a capillary liquid chromatography with MS detection for the determination at ngg⁻¹ levels of four heterocyclic aromatic amines (MeIQx, norharman, harman and harmine), a group of mutagenic and carcinogenic compounds that can potentially be produced in protein-rich food during processing operations. They have been determined in commercial ready-to-eat (RTE) smoked salmon and soft cheese treated with E-beam irradiation. On the basis of experimental design studies and operating conditions of MS detector, best chromatographic conditions were obtained using a Luna® C¹8 capillary column (150 mm × 0.3 mm I.D.) with a mixture of acetonitrile-ammonium formate 5 mM pH 3.6 buffer (13:87, v/v) as mobile phase. To improve sensitivity, large injection volumes (20 µL) and injection solutions of low elution strength were employed. Sample preparation procedure included a previous treatment with 1M NaOH, followed by two solid-phase extraction steps; firstly on diatomaceous earth and then on mixed-mode cartridges. Heterocyclic amines were detected neither in irradiated and in non-irradiated samples, indicating that they were not formed by the radiation effect even at doses higher than those indicated in the Food Safety Objective established by regulatory agencies. RTE food samples were spiked at concentration levels in the range 10-30 ngg⁻¹. Recoveries higher than 85% (n=3 for each spiked level) were obtained, showing the effectiveness of the proposed methodology.

Determination of heterocyclic aromatic amines by capillary high-performance liquid chromatography with diode array detection in ready-to-eat cooked ham treated with electron-beam irradiation.

Heterocyclic aromatic amines (HAs) are a group of mutagenic and carcinogenic substances present in significant amounts in cooked meat and fish that can potentially be formed during food processing operations. This paper proposes a capillary liquid chromatography method with diode array detection for the trace-level determination of three HAs, namely, MeIQx (2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline), norharman (9H-pyrido[3,4-b]indole) and harman (1-methyl-9H-pyrido[3,4-b]indole), in ready-to-eat (RTE) cooked ham processed by electron-beam (accelerated electrons) irradiation to eliminate pathogenic microorganisms and to extend its shelf-life. The HAs selected have frequently been detected and quantified in a wide range of food and could be potential markers to indicate the presence of these toxic compounds. The method is based on the separation in an Inertsil C(8) capillary column (150 mm x 0.3-mm internal diameter, 3 microm) by gradient elution mode using a mixture of acetonitrile and 30 mM ammonium acetate pH 4.5 buffer as the mobile phase. Detection was at 250 and 265 nm and, to improve sensitivity, large injection volumes (20 microL) and on-column focusing techniques based on the injection of HA samples in low organic solvent strength solutions were employed. A simple and short solid-phase extraction and purification procedure was also optimized for sample preparation. Nonirradiated and irradiated RTE cooked ham samples at doses between 1 and 8 kGy were analyzed. HAs were not detected in any of the samples analyzed; so both types of samples were spiked at concentration levels in the range 5-25 ng g(-1), which may be found in meat products. The quality parameters of the method developed in the food matrix were established, and detection limits around 0.3 ng g(-1) were obtained. Spiked recoveries between 70 and 79% (n = 3 for each spiked level) relative standard deviations between 1 and 5% were also obtained, showing the effectiveness of the proposed method.

Study of nitrophenols preconcentration using quinolin-8-ol immobilized on controlled-pore glass in the presence of iron(III). Chromatographic determination of dinoseb in lemon juice.

The efficiency of an adsorbent consisting of quinolin-8-ol immobilized on controlled-pore glass which was packed in a minicolumn to preconcentrate nitrophenols in the presence of iron(III) has been established. Retention was carried out at acidic pH in the presence of 20 mM iron(III). Methanol-30 mM formic acid-sodium formate aqueous solution (pH 4.2) (65:35) was used in a one-step elution. Determinations were carried out by using liquid chromatography with detection at 350 nm. Determination of trace amounts of dinoseb in lemon juice was carried out with a minimum sample preparation. Recoveries were between 89 and 100% at 200-33 micrograms l-1. The maximum admissible concentration in fruit juice dictated by the Spanish and European Community legislation can be measured.