Analysis Of Heterocyclic Aromatic Amines Research Articles

Development of a Modified QuEChERS Method Based on Magnetic Multi-Walled Carbon Nanotubes as a Clean-Up Adsorbent for the Analysis of Heterocyclic Aromatic Amines in Braised Sauce Beef.

Heterocyclic aromatic amines (HAAs) generated during the cooking of meats cause adverse effects on human health. The purpose of the current research was to develop a modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged, Safe) method using magnetic multi-walled carbon nanotubes (Fe3O4-MWCNTs) as clean-up adsorbents for the rapid determination of HAAs in braised sauce beef. The significant parameters in extraction and clean-up processes were screened and optimized. Under optimal conditions, the LODs ranged from 3.0 ng/g to 4.2 ng/g. The recoveries (78.5−103.2%) and relative standard deviations RSDs (<4.6%) of five HAAs were obtained. These are in accordance with the validation criteria (recovery in the range of 70−120% with RSD less than 20%). Compared with conventional clean-up adsorbents (PSA or C18), Fe3O4-MWCNTs displayed equivalent or better matrix removal efficiency, while making the pretreatment process easier and more time-saving through magnetic separation. Less usage of adsorbent makes the method possess another advantage of being lower in cost per sample. The method developed was successfully applied to analyze real samples collected from local deli counters, demonstrating Fe3O4-MWCNTs could be considered as an effective alternative adsorbent with great potential in the QuEChERS process.

Improved enrichment and analysis of heterocyclic aromatic amines in thermally processed foods by magnetic solid phase extraction combined with HPLC-MS/MS

Heterocyclic aromatic amines (HAAs) are potently mutagenic and carcinogenic compounds formed during thermal processing foods. However, due to the complexity of the food matrix and trace levels of HAAs, rapid and effective detection of HAAs has always been a challenge. In this study, novel magnetic covalent organic polymers (Fe3O4@COP) were synthesized as adsorbents for effectively and rapidly enriching HAAs. Meanwhile, the proposed materials were endowed with good selectivity and superior purification ability to effectively alleviate the matrix effect interference of complex food samples. Then, a reliable and sensitive method was developed for the determination of HAAs by magnetic solid-phase extraction combined with HPLC-MS/MS. The established method displayed good linearity (R2 ≥ 0.9984) with the satisfactory limits of detection (0.020–0.375 μg kg−1) and recoveries (82.0–109.5%). Further, the developed method was applied to determine HAAs in different types of thermally processed meat products, showing excellent applicability. Results showed that different thermal processing methods promoted the generation of HAAs in the order of frying, roasting and grilling, and boiling. Norharman and Harman were the predominant HAAs in thermally processed meat products.

Analysis of heterocyclic aromatic amines using selective extraction by magnetic molecularly imprinted polymers coupled with liquid chromatography - Mass spectrometry.

Heterocyclic aromatic amines (HCAs) are highly carcinogenic and mutagenic chemicals. This study reports on the development of magnetic molecularly imprinted polymers (MMIPs) for the purification and quantification of HCAs. A novel magnetic molecularly imprinted polymer was successfully prepared using a surface molecular imprinting method using functionalized Fe particles as the magnetic cores. 2-Amino-3-methylimidazo[4,5-f]quinoline (IQ) was used as a molecular template; methacrylic acid (MAA), ethylene glycol dimethyl acrylate (EGDMA), 2, 2'-Azobis (2-methylpropionitrile) were used as the functional monomer, crosslinker, and initiator, respectively. The use of the template/functional monomer/crosslinking agent at a ratio of 1:4:20 resulted in a product with better adsorption properties (3.24 mg/g). The HCAs were successfully detected and quantified in processed meat samples by MISPE and LC-MS/MS. Under the final optimized detection conditions, the proposed method offered good linearity (R > 0.995) for the five HCAs with an acceptable level of precision, and an LOQ of 0.05 ng/g was successfully achieved.

Multi-response optimization of a green solid-phase extraction for the analysis of heterocyclic aromatic amines in environmental samples

A method for the multi-response optimization of a green and efficient solid phase extraction treatment combined with liquid chromatography-tandem mass spectrometry was developed for the quantification of ten heterocyclic aromatic amines in waters.

Simultaneous determination of 9 heterocyclic aromatic amines in pork products by liquid chromatography coupled with triple quadrupole tandem mass spectrometry

Heterocyclic aromatic amines (HAAs) are potent mutagens that formed at high temperature in cooked, protein-rich food. Owing to their frequent intake, an accurate method is essential to access human health risk of HAAs exposure through detecting these compounds in various heat-treated meat products. In this study, a liquid chromatography-electrospray tandem mass spectrometry (LC--ESI-MS/MS) method was developed to perform the determination of 9 mutagenic heterocyclic amines (HAAs) in meat samples with multiple reaction monitoring (MRM) mode. Ultrasound assisted extraction and diatomaceous earth was employed to extract HAAs from food samples, and the analytes were purified and enriched using tandem solid phase extraction, with propyl sulfonic acid coupled to a C18 cartridge. Two parameters, extraction time and eluent, were carefully optimized to improve the extraction and purification efficiency. The LC separation was carried out using a Zorbax SB-C18 (3.5 μm particle size, 2.1 × 150 mm i.d.) column and optimized some parameters, such as pH, concentration and volume. Under the optimal experimental conditions, recoveries ranged from 52.97% to 97.11% with good quality parameters: limit of detection values between 0.02 and 0.24 ng mL-1, linearity (R2>0.998), and run-to-run and day-to-day precisions lower than 9.81% achieved. To evaluate the performance of the method in high throughput analysis of complex meat samples, the LC-MS/MS method was applied to the analysis of HAAs in three food samples, and the results demonstrated that the method can be used for the trace determination of HAAs in pork samples.

Preparation of arginine-modified reduced graphene oxide composite filled in an on-line solid-phase extraction disk and its application in the analysis of heterocyclic aromatic amines.

An arginine-modified reduced graphene oxide composite was prepared in an on-line solid-phase extraction disk and coupled to high-performance liquid chromatography for the re-enrichment of heterocyclic aromatic amines. The synthetic composite presented an excellent adsorption capability because of the ultrahigh active surface area of graphene and the abundant alkaline groups of arginine. The adsorption capacity of it was 52.7mg 2-amino-3-methyl-imidazo[4,5-f]-quinoline per gram, nearly twice that of threonine-modified reduced graphene oxide composite, glutamic acid modified reduced graphene oxide composite, and reduced graphene oxide. This on-line method was successfully applied to the detection of a series of heterocyclic aromatic amines in beef jerky. After clean-up and re-enrichment of the on-line solid-phase extraction disk, the chromatographic background of the sample was low and the shape of chromatographic peaks was sharp. The method detection limit was in the range of 0.30-0.49ng/g, and the recovery was in the range of 82.0-111.5%.

Heterocyclic aromatic amines content in chicken burgers and chicken nuggets sold in fast food restaurants and effects of green tea extract and microwave thawing on their formation

The aims of the study were to investigate the presence of heterocyclic aromatic amines (HCAs) in chicken burgers (CBs) and chicken nuggets (CNs) purchased from fast food restaurants and the effects of green tea extract addition (GTE) into the covering material as well as microwave thawing (MT) on HCAs formation in CBs and CNs. Analysis of HCAs (IQx, IQ, MeIQx, MeIQ, 7,8-DiMeIQx, 4,8-DiMeIQx, PhIP, AαC, and MeAαC) were performed using HPLC-DAD following solid phase extraction. While the total HCAs content varied between not quantified—9.72 ng/g meat and 1.94–22.01 ng/g meat for commercial CBs and CNs, it ranged between not quantified—3.42 ng/g meat and not quantified—0.31 ng/g meat for CBs and CNs produced in the laboratory, respectively. Commercial CBs and CNs contained high amounts of HCAs, with MeIQx being the dominant HCA in all analyzed samples however, GTE and MT did not reduce the HCAs formation in CBs and CNs. Practical applications Widely consumed fast food chicken products; chicken burgers and chicken nuggets contain high amounts of HCAs. That much HCA concentration in chicken burgers and chicken nuggets can endanger the public health seriously.

Porous boronate affinity monolith for on-line extraction coupled to high-performance liquid chromatography for sensitive analysis of heterocyclic aromatic amines in food samples

Abstract A novel on-line solid-phase microextraction–high-performance liquid chromatography (SPME–HPLC) system was developed for the determination of heterocyclic aromatic amines (HAAs) in food samples. A poly(vinylphenylboronic acid-co-ethylene glycol dimethacrylate) polymer monolith was prepared for on-line efficient extraction and large-volume injection was used to increase the sensitivity of detection. The polymermonolith, based on a ternary porogen, was prepared by in situ polymerization of vinylphenylboronic acid (VPBA) and ethylene glycol dimethacrylate (EGDMA) in a fused-silica capillary column. It showed good permeability, high extraction capacity, and high selectivity. The column-to-column reproducibility was satisfactory, and the enrichment factors for HAAs were 3746–7414. Conditions influencing the on-line extraction efficiency, including pH of sample solutions, flow rate of extraction and desorption, and desorption volume, were investigated. The proposed method had low limit of detection (0.10–0.15 ng/L) and good linearity. Trace HAAs in roast beef and lamb samples were determined, and the amounts of 2-amino-3-methylimidazo[4,5-f]quinoline, 2-amino-3,4-dimethylimidazo[4,5-f]quinoline, 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline, 2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline, and 2-amino-3,4,7,8-tetramethyl-3 H -imidazo[4,5-f]quinoxaline in these samples were 0.235–2.08 ng/g. The recoveries for the five HAAs ranged from74.3% to 119%, and the relative standard deviation (RSDs) were less than 8.2%. The results showed that the proposed on-line method was highly sensitive for monitoring HAAs in different food samples.

Preconcentration and Simultaneous Determination of Heterocyclic Aromatic Amines in Grilled Pork Samples by Ion-Pair-Based Surfactant-Assisted Dispersive Liquid-Liquid Microextraction and High-Performance Liquid Chromatography

An effective ion-pair-based surfactant-assisted dispersive liquid-liquid microextraction combined with high-performance liquid chromatography (HPLC) has been evaluated for the extraction and preconcentration of four heterocyclic aromatic amines (i.e., 2-amino-3,4-dimethyl-3H-imidazo[4,5-f]quinoline (MeIQ); 2-amino-3,4,8-trimethyl-3H-imidazo[4,5-f]quinoxaline (4,8-DiMeIQx); 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP); and 1-methyl-9H-pyrido[3,4-B]indole (Harmane)). In the extraction method, sodium dodecyl sulfate (SDS) was used as both ion-pairing and disperser agent and 1-octanol was selected as extraction solvent. The effects of various parameters on the extraction efficiency such as kind and concentration of surfactant, kind and volume of extraction, salt addition, vortex extraction, and centrifugation time were investigated. Under the selected condition, the method provided high enrichment factor in the ranged of 124–145. Good linearity was 0.01–1000 μg kg−1 with the correlation coefficient (R 2) > 0.999. The limit of detection was 0.01 μg kg−1 for all compounds. The matrix match calibration was used for quantitation of the target analytes in grilled pork samples. The proposed method was successfully applied to analysis of heterocyclic aromatic amines in grilled pork samples where good recoveries were obtained in the range of 90 and 106 %.

Quantitative Analysis of Six Heterocyclic Aromatic Amines in Mainstream Cigarette Smoke Condensate Using Isotope Dilution Liquid Chromatography-Electrospray Ionization Tandem Mass Spectrometry

Heterocyclic aromatic amines (HAAs) represent an important class of carcinogens in mainstream cigarette smoke. Accurate HAA quantification is challenging because of their relative low abundances and numerous chemical interferences that arise naturally from thousands of the constituents present in cigarette smoke. We have developed and validated a straightforward high-throughput method to quantify HAA levels in mainstream cigarette smoke and demonstrated the applicability by analyzing select research and domestic cigarette brands. Machine-smoked cigarette condensate collected under both standard and intensive smoking regimens was examined. Mainstream smoke particulate from individual cigarettes trapped on a glass fiber filter pad was spiked with an appropriate internal standard solution and subsequently solvent extracted. The extract was quantitatively analyzed by high-performance liquid chromatography and tandem mass spectrometry. Method validation data showed excellent accuracy, reproducibility and high throughput; it is suitable for the routine analysis of HAAs in cigarette smoke condensate delivered under a wide of differing smoking conditions. The smoking machine deliveries of HAAs are strongly influenced by cigarettes' physical design, filler blend, and smoking regimen. A quick and accurate method has been developed for the analysis of 6 HAAs in mainstream cigarette smoke condensate. Results provided a good mean to access the ranges of HAAs in commercial products and evaluate the relative contribution of cigarette design, filler blend, and smoking regimen on delivery. Such data are vital in helping provide exposure ranges for potential human exposure estimates.

Validation of an ion-pair liquid chromatography–electrospray-tandem mass spectrometry method for the determination of heterocyclic aromatic amines in meat-based infant foods

A method based on ion-pair liquid chromatography–electrospray tandem mass spectrometry (LC–MS/MS) is reported for determining heterocyclic aromatic amines (HAAs) in meat-based infant foods. The HAAs encompassed quinoline (IQ, MeIQ), quinoxaline (MeIQx), pyridine (PhIP), and carboline derivatives (AαC, Harman, Norharman) with d3-IQ, 13C2-MeIQx, and d3-PhIP used as labelled internal standards. The method used extraction into acetone followed by a clean-up on an SCX solid-phase extraction column. LC separation was performed on a TSKgel ODS-80TS column (250 × 2.0 mm, 5 µm), the mobile phase being an ammonium formate–formic acid buffer (3.03 mM ammonium formate, pH = 2.8) aqueous solution–acetonitrile gradient at a flow rate of 0.2 ml min−1. For unequivocal identification of each analyte, three ions were detected and chosen for selected reaction monitoring (SRM). Validation was carried out on lyophilized meat samples. Mean recoveries ranged between 78 ± 4% and 98 ± 2% for different analytes. Limits of quantification generally lower than 8 ng g−1 were demonstrated in meat samples for the analytes investigated. The method exhibited a good linearity and repeatability. Robustness testing identified those factors which were statistically significant in influencing chromatographic separation and response, and indicated which parameters have to be strictly controlled for a reliable analysis of HAAs. In particular, the mobile-phase flow rate was found to be statistically significant (α = 0.05) for the capacity factor (k′) of all analytes except for AαC peak, whereas the mobile-phase pH resulted to be a critical parameter for the k′ values of IQ, MeIQ, and Norharman. The method was proved to be robust vs. resolution between IQ and MeIQ peaks. Among mass-spectrometric parameters, collision energy was found to significantly affect quantitative response of all analytes except that of IQ. The applicability of the method to the analysis of meat-based infant food samples was demonstrated.

Assessment of metastable atom bombardment (MAB) ionization mass spectrometry for the fast determination of heterocyclic aromatic amines in cooked meat

An investigation of metastable atom bombardment (MAB) ionization mass spectrometry for the fast characterization of mutagenic/carcinogenic heterocyclic aromatic amines (HAAs) formed during heating processes of meats is presented. The aim of our study was to use the selective ionization of MAB to develop a detection method for HAAs in non-purified meat extracts, thus avoiding purification and concentration steps and reducing analysis time. Sample introduction into the MAB ion source was achieved by pyrolysis, allowing the direct and fast insertion of complex food extracts into the mass spectrometer. Analysis conditions were optimized on standard HAAs by using different ionization gases for the MAB process. Metastable nitrogen was selected as the best MAB gas for the analysis of HAAs. Ionization selectivity is shown by the detection of heterocyclic amines in non-purified chicken meat extracts spiked with HAAs. A quantitative approach is also presented by using pyrograms as chromatograms for quantification purposes. HAAs determination using Py-MAB-ToF was finally performed on cooked chicken breast extracts and compared to an LC-APCI-MS/MS method. Although Py-MAB-ToF sensitivity remains to be improved in the present state of development of our prototype device, only 2 h from the cooking were required to obtain quantitative results in good agreement with HAAs concentrations measured by LC-MS/MS in 36 h. Figure Experimental set-up for pyrolysis-MAB-ToF mass spectrometry experiments.

Analysis of heterocyclic aromatic amines in foods by gas chromatography?mass spectrometry as their tert.-butyldimethylsilyl derivatives

A derivatization method for the analysis of 12 heterocyclic aromatic amines (HAs) in food, by gas chromatography–electron impact mass spectrometry, was developed. The amines are derivatized in a one-step reaction with N-methyl-N-(tert.-butyldimethylsilyl)trifluoroacetamide. The derivatives are characterized by easy-to-interpret mass spectra due to the prominent ion [M-57]+ by loss of a tert.-butyldimethylsilyl group, allowing quantification in the selected-ion monitoring mode at the picogram level. The effect of temperature, time, and reagents on the formation of the derivatives was monitored in detail. Quality parameters were evaluated in the optimum working conditions. This derivatization method is not applicable to the pyridoimidazoles Glu-P-1 and Glu-P-2 and to the β-carboline harman due to incompletely derivatization. The instability of the imidazolquinoline and imidazoquinoxaline derivatives, requiring their injection on the same working day, is a further drawback. This simple, rapid and accurate derivatization procedure is suitable for routine analysis, as illustrated by the analysis of some common foods.

Analysis of heterocyclic aromatic amines in foods by gas chromatography–mass spectrometry as their tert.-butyldimethylsilyl derivatives

A derivatization method for the analysis of 12 heterocyclic aromatic amines (HAs) in food, by gas chromatography–electron impact mass spectrometry, was developed. The amines are derivatized in a one-step reaction with N-methyl- N-( tert.-butyldimethylsilyl)trifluoroacetamide. The derivatives are characterized by easy-to-interpret mass spectra due to the prominent ion [ M-57] + by loss of a tert.-butyldimethylsilyl group, allowing quantification in the selected-ion monitoring mode at the picogram level. The effect of temperature, time, and reagents on the formation of the derivatives was monitored in detail. Quality parameters were evaluated in the optimum working conditions. This derivatization method is not applicable to the pyridoimidazoles Glu-P-1 and Glu-P-2 and to the β-carboline harman due to incompletely derivatization. The instability of the imidazolquinoline and imidazoquinoxaline derivatives, requiring their injection on the same working day, is a further drawback. This simple, rapid and accurate derivatization procedure is suitable for routine analysis, as illustrated by the analysis of some common foods.

Evaluation of reversed-phase columns for the analysis of heterocyclic aromatic amines by liquid chromatography—electrospray mass spectrometry

Liquid chromatography coupled to mass spectrometry (LC–MS), especially by the use of electrospray ionisation source (ESI), is currently used for the analysis of heterocyclic aromatic amines (HAs) in complex samples. The present paper describes the study of the performance of different narrow-bore reversed-phase columns to achieve the best chromatographic separation for the determination of 16 HAs by LC–ESI-MS in food samples. Different parameters such as peak symmetry, resolution and number of theoretical plates have been evaluated for each column, using different chromatographic conditions. The column that provided the best results was TSK Gel ® Semi-Micro ODS-80TS of Tosohaas. Quality parameters have been established, obtaining good short-term precision in all cases (relative standard deviation (R.S.D.) lower than 7.7%) and low limits of detection (<13 pg injected in MS and <16 pg injected in MS/MS). The content of HAs in two beef extracts have been determined.

Solid-phase microextraction coupled with high-performance liquid chromatography for the analysis of heterocyclic aromatic amines

Solid-phase microextraction (SPME) coupled with high-performance liquid chromatography (HPLC) with UV diode array detection (DAD) for the analysis of heterocyclic aromatic amines (HAs) is described. Four kinds of fiber coatings: Carbowax–templated resin (CW–TPR), Carbowax–divinylbenzene (CW–DVB), poly(dimethylsiloxane)–divinylbenzene (PDMS–DVB) and polyacrylate (PA) were evaluated for extraction of nine most biologically active heterocyclic aromatic amines. Different parameters affecting to the microextraction and determination of HAs were studied, such as absorption and desorption time, desorption mode, composition of the solvent for desorption, pH, ionic strength, and percentage of methanol in the sample. To determine these amines in food samples a new simplified procedure is proposed, consisting of treatment of the sample with methanolic NaOH prior microextraction by CW–TPR fiber coating and HPLC–DAD determination. The advantages of this new method are the reduced amounts of time and organic solvents required.

Determination of heterocyclic aromatic amines by capillary electrophoresis coupled to mass spectrometry using in-line preconcentration.

This paper shows the potentiality of capillary electrophoresis (CE) coupled to mass spectrometry (MS) for the analysis of heterocyclic aromatic amines obtaining good results in terms of sensitivity and precision. These compounds have a special interest since they can be carcinogenic for humans. The optimization of a CE-MS method was performed and the best conditions were obtained using a 16 mM formic acid/ammonium formate solution at pH 4.5 with 60% methanol as running electrolyte. For CE-MS coupling, a sheath liquid methanol/20 mM formic acid (75/25) solution at a flow rate of 3 microL/min and hydrodynamic injection of methanol mixtures for 10 s were used. Detection limits ranging from 18 ng/g to 360 ng/g and precisions up to 1.4% and 12% for migration time and concentration, respectively, were obtained. In order to improve sensitivity, field-amplified sample injection was applied as an in-line preconcentration method. Methanol/5 mM formic acid (50/50) as a sample solvent, 3 s hydrodynamic injection (0.5 psi) of a methanol plug, and 25 s of electrokinetic injection (10 kV) of the sample were found to be the optimum conditions. Detection limits up to 25 times lower and similar precisions than those reported for hydrodynamic injection were obtained.

Clean-up procedures for the analysis of heterocyclic aromatic amines (aminoazaarenes) from heat-treated meat samples

The purpose of the study was to determine optimum conditions for the isolation and quantitation of five most biologically active aminoazaarenes {2-amino-3-methylimidazo[4,5- f]quinoline (IQ), 2-amino3,4-dimethylimidazo[4,5- f]quinoline (MeIQ), 2-amino-3,8-dimethyl-imidazo[4,5- f]quinoxaline (MeIQx), 2-amino-3,4,8-trimethylimidazo[4,5- f]quinoxaline (4,8-DiMeIQx), 2-amino-1-methyl-6-phenylimidazo[4,5- b]pyridine (PhIP)}. Some multistep procedures based on ultrasonic extraction, Soxhlet extraction, liquid–liquid extraction and solid-phase extraction (SPE) were tested in order to choose the optimum isolation conditions for aminoazaarenes from fried meat samples spiked with known amounts of standards. According to the tested methods the qualitative–quantitative analysis was performed on the unspiked sample of pork roasted in typical household conditions. The qualitative–quantitative analysis of the aminoazaarenes was performed by a HPLC method. A HPLC Hewlett-Packard HP 1090 liquid chromatograph equipped with a UV diode array detector (DAD) was used. Chemically bonded HPLC columns C 8 and TSK-gel ODS 80-T M were used under gradient elution conditions. A two-component mixture containing triethylamine–phosphate buffer (pH 3.2 and 3.3) and acetonitrile was used as a mobile phase. The results of the studies showed that a solid-phase extraction procedure using diatomaceous earth (Extrelut, 20 ml), propylsulphonic acid (PRS, 500 mg) and octadecylsilane (C 18, 500 mg) columns was the quickest and simplest one. Recoveries of the aminoazaarenes, spiked and isolated from meat samples by the chosen SPE procedure, were as follows: IQ 85%, MeIQ 50%, MeIQx 46%, 4,8-DiMeIQx 62%, PhIP 50%.

Analysis of heterocyclic aromatic amines by high resolution gas chromatography-mass spectrometry: a suitable technique for the routine control of food and process flavours

Ten heterocyclic aromatic amines (HAA; [2-amino-3-methyl-3H-imidazo[4,5-f]quinoline (1); 2-amino-3,4-dimethyl-3H-imidazo[4,5-f]quinoline (2); 2-amino-3-methyl-3H-imidazo[4,5-f]quinoline (3); 2-amino-3,8-dimethyl-3H-imidazo[4,5-f]quinoline (4); 2-amino-3,4,8-trimethyl-3H-imidazo[4,5-f]quinoline (5); 2-amino-3,7,8-trimethyl-3H-imidazo[4,5-f]quinoline (6); 2amino-3,4,7,8-tetramethyl-3H-imidazo[4,5-f]quinoline (7); 2-amino-1-methyl-6-phenyl-imidazo[4,5-f]quinoline (8); 2-amino-6-methyldipyrido[1,2-α : 3′,2′-d]imidazole (9); 2-aminodipyrido[1,2-α : 3′,2′-d]imidazole (10)]) were analysed in commercially available meat products and process flavours. After sample preparation by Extrelut treatment, subsequent solid phase extraction applying propylsulphonic and C18 silica cartridges, as well as derivatization with 3,5-bis-trifluoromethylbenzyl bromide, HRGC-electron-impact-ionization-MS (HRGC-EIMS) analysis in the selected ion monitoring mode was performed. Isotope dilution analysis with 2amino-8-methyl-3-(trideuteromethyl)-3H-imidazo[4,5- f]quinoxaline and 2-amino-1-(trideuteromethyl)-6-phenyl-imidazo[4,5-b]pyridine was used to quantify 4 and 8; for 1–3, 5–7, 9 and 10, standard addition was employed as the determination method. The detection limit of 1 ng/g evaluated for 3–6 and 9 was sufficient for routine analysis, i.e. to obtain an initial insight into the grade of a potential HAA contamination of food or process flavours. To obtain more detailed information, the previously developed, more sensitive technique of HPLC-electrospray-tandem-MS (HPLC-ESI-MS/MS) has to be used, as shown by the comparison of the data obtained by HRGC-MS and HPLC-ESI-MS/MS analyses.

Evaluation of different clean-up procedures for the analysis of heterocyclic aromatic amines in a lyophilized meat extract

Along with other mutagenic and carcinogenic contaminants in foods such as aflatoxins and polycyclic aromatic hydrocarbons, heterocyclic aromatic amines (HAAs) have received considerable attention in recent years. A major drawback in the analysis of HAAs in foods is their very low level of concentration (0.1–50 ng g −1) as well as matrix interferences. Solid-phase extraction (SPE), forming an integral part of chromatographic analysis, is one of the procedures currently used for the extraction and purification of HAAs in food samples. In this paper a comparative study of several SPE procedures for HAAs determination was performed. Recoveries of the heterocyclic amines in the analysis of both a simple matrix such as a standard methanolic solution and a contaminated meat extract were established. HAAs were determined by HPLC analysis with photodiode-array detection (DAD) of the purified extracts, and the adequacy of different clean-up procedures for the analysis of a contaminated meat extract was discussed.