Hydrophilic-interaction-based magnetically assisted matrix solid-phase dispersion extraction of carbadox and olaquindox in feeds.

BACKGROUND: Carbadox and olaquindox have been banned from feeds since 1998 by the EU because of their mutagenic, photoallergic, and carcinogenic effects. Unfortunately, owing to their outstanding effect, they are frequently abused or misused in animal husbandry. There is an urgent need to develop a sensitive and reliable method for monitoring these drugs in animal feeds. RESULTS: This work reported a new method of hydrophilic-interaction-based magnetically assisted matrix solid-phase dispersion (MMSPD) extraction coupled with reversed-phase liquid chromatography-mass spectrometry for simultaneous determination of carbadox and olaquindox in animal feeds. 3-Trimethoxysilylpropyl methacrylate (γ-MAPS)-modified attapulgite (ATP) was crosslinked with γ-MAPS-modified iron(II,III) oxide (Fe3 O4 ), 1-vinyl-3-(butyl-4-sulfonate) imidazolium (VBSIm), acrylamide (AM), and N,N'-methylene-bis(acrylamide) (MBA) to synthesize ATP@Fe3 O4 @poly(VBSIm-AM-MBA) particles. The resultant particles were characterized by scanning electron microscopy, energy dispersive spectrometer, transmission electron microscopy, vibrating sample magnetometer, and Fourier transform infrared spectroscopy. Crosslinking of ATP into the magnetic particles has significantly increased the adsorption capacity of the particles. Under optimum conditions, the limits of detection (S/N = 3) were 0.3 µg kg-1 and 0.9 µg kg-1 for carbadox and olaquindox respectively. The intra-day and inter-day recoveries of the spiked targets in feed samples were in the range 83.5-98.3% with relative standard deviations of 1.0-8.3%. CONCLUSION: With a simplified procedure and a low amount of sample, the proposed hydrophilic-interaction-based MMSPD method is not only useful for the determination of carbadox and olaquindox in feeds but also holds great promise for the analysis of other polar targets in solid or semisolid matrices. © 2021 Society of Chemical Industry.

A Photoaffinity-Based Fragment-Screening Platform for Efficient Identification of Protein Ligands.

Advances in genomic analyses enable the identification of new proteins that are associated with disease. To validate these targets, tool molecules are required to demonstrate that a ligand can have a disease-modifying effect. Currently, as tools are reported for only a fraction of the proteome, platforms for ligand discovery are essential to leverage insights from genomic analyses. Fragment screening offers an efficient approach to explore chemical space. Presented here is a fragment-screening platform, termed PhABits (PhotoAffinity Bits), which utilizes a library of photoreactive fragments to covalently capture fragment-protein interactions. Hits can be profiled to determine potency and the site of crosslinking, and subsequently developed as reporters in a competitive displacement assay to identify novel hit matter. The PhABit platform is envisioned to be widely applicable to novel protein targets, identifying starting points in the development of therapeutics.

Molecularly imprinted electrochemical sensor based on polypyrrole/dopamine@graphene incorporated with surface molecularly imprinted polymers thin film for recognition of olaquindox.

In this paper, an advanced molecularly imprinted electrochemical sensor (MIECS) based on electropolymerized olaquindox (OLA) surface molecularly imprinted polymer thin film on a modified glassy carbon electrode (GCE) was developed for the detection of OLA. It was fabricated by coating dopamine@graphene (DGr) on GCE, then electropolymerizing pyrrole (Py) and molecularly imprinted polymers (MIPs). Graphene (Gr) was introduced for improving conductivity and sensitivity. Dopamine (DA) was used for dispersion and adhesion of Gr. Polypyrrole (PPy) could fix DGr and enhance the current response evidently. The established sensor could selectively recognize OLA but not the analogs of OLA. Some essential parameters controlling the performance of the developed sensor were investigated and optimized. Under optimal conditions, the linear relationship between the current intensity and OLA concentration was obtained from 50 nmol L-1 to 500 nmol L-1 with a limit of detection (LOD) of 7.5 nmol L-1. Analytical results of OLA based on the developed MIECS for fish and feedstuffs showed a good agreement with the results based on high performance liquid chromatography (HPLC).

Tracing major metabolites of quinoxaline-1,4-dioxides in abalone with high-performance liquid chromatography tandem positive-mode electrospray ionization mass spectrometry.

BACKGROUND: Owing to the comprehensive application of quinoxaline-1,4-dioxides (QdNOs) in aquaculture, QdNOs and metabolites are often detected in marine food, including abalone. QdNOs are reported to exhibit cytotoxicity, photoallergy, mutagenicity, and carcinogenicity activities. To monitor for contamination of QdNOS in abalone and assess dietary exposure, a simple and reliable analytical method for the detection of QdNOs and their major metabolites was developed. RESULTS: This work is the first to present a simple and fast pretreatment procedure coupled with high-performance liquid chromatography tandem positive-mode electrospray ionization mass spectrometry (LC-MS/MS) for tracing of major metabolites of QdNOs in abalone. Extraction steps were simplified by the use of methanol and ethyl acetate containing 0.1% formic acid instead of more complicated acidolysis and enzymolysis pretreatment procedures. High-sensitive characters were obtained with limits of detection ranged from 0.16 to 2.1 µg kg-1 for QdNOs and their major metabolites. CONCLUSION: These results indicate that the LC-MS/MS method developed could be applied for QdNOs and major metabolites detection in actual samples. Considering the large production and consumption of abalone in Shandong Province, China, this work will also contribute to the further understanding of the often-ignored exposure pathway of QdNOs. © 2019 Society of Chemical Industry.

Biomonitoring DNA Adducts of Cooked Meat Carcinogens in Human Prostate by Nano Liquid Chromatography-High Resolution Tandem Mass Spectrometry: Identification of 2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine DNA Adduct.

Epidemiologic studies have reported an association between frequent consumption of well-done cooked meats and prostate cancer risk. However, unambiguous physiochemical markers of DNA damage from carcinogens derived from cooked meats, such as DNA adducts, have not been identified in human samples to support this paradigm. We have developed a highly sensitive nano-LC-Orbitrap MS n method to measure DNA adducts of several carcinogens originating from well-done cooked meats, tobacco smoke, and environmental pollution, including 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), 2-amino-9H-pyrido[2,3-b]indole (AαC), 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx), benzo[a]pyrene (B[a]P), and 4-aminobiphenyl (4-ABP). The limit of quantification (LOQ) of the major deoxyguanosine (dG) adducts of these carcinogens ranged between 1.3 and 2.2 adducts per 10 9 nucleotides per 2.5 µg of DNA assayed. The DNA adduct of PhIP, N-(deoxyguanosin-8-yl)-PhIP (dG-C8-PhIP) was identified in 11 out of 35 patients, at levels ranging from 2 to 120 adducts per 10 9 nucleotides. The dG-C8 adducts of AαC and MeIQx, and the B[a]P adduct, 10-(deoxyguanosin-N 2 -yl)-7,8,9-trihydroxy-7,8,9,10-tetrahydrobenzo[a]pyrene (dG-N 2 -B[a]PDE) were not detected in any specimen, whereas N-(deoxyguanosin-8-yl)-4-ABP (dG-C8-4-ABP) was identified in one subject (30 adducts per 10 9 nucleotides). PhIP-DNA adducts also were recovered quantitatively from formalin fixed paraffin embedded (FFPE) tissues, signifying FFPE tissues can serve as biospecimens for carcinogen DNA adduct biomarker research. Our biomarker data provide support to the epidemiological observations implicating PhIP, one of the most mass-abundant heterocyclic aromatic amines formed in well-done cooked meats, as a DNA-damaging agent that may contribute to the etiology of prostate cancer.

Impact of Precursors Creatine, Creatinine, and Glucose on the Formation of Heterocyclic Aromatic Amines in Grilled Patties of Various Animal Species.

The impact of precursors such as creatine, creatinine, and glucose on the formation of mutagenic/carcinogenic heterocyclic amines (HAs) were studied in patties of 9 different animal species equally heat treated with a double-plate contact grill. All grilled patties of the various species (veal, beef, pork, lamb, horse, venison, turkey, chicken, ostrich) contained several HAs such as MeIQx (2-amino-3,8-dimethylimidazo[4,5-f] quinoxaline; 0.5-1.4 ng/g), 4,8-DiMeIQx (2-amino-3,4,8-trimethylimidazo[4,5-f] quinoxaline, 0 to 1.3 ng/g), PhIP (2-amino-1-methyl-6-phenylimidazo[4,5-b] pyridine, 1.2 to 10.5 ng/g), harman (1-methyl-9H-pyrido[3,4-b] indole; 0.5 to 3.2 ng/g), and/or norharman (9H-pyrido[3,4-b]indole 0.5 to 1.9 ng/g). Residual glycogen (glucose) content varied greatly from 0.07 to 1.46 wt% on a dry matter (DM) basis. Total creatin(in)e content in raw meat (1.36 to 2.0 wt% DM) hardly differed between species, except in turkey and ostrich (1.1 wt% DM). Chicken contained, compared to all other species, very low concentrations of glucose (0.07 wt% DM) and the highest levels of nonprotein nitrogen compounds. The free amino acids lysine (r = 0.77, P < 0.001), tyrosine, phenylalanine, proline, isoleucine, and aspartic acid (r = 0.47-0.56, P < 0.05) showed significant correlation to PhIP in chicken. Also a linear correlation was found to exist between PhIP (r = 0.87, P < 0.001) and MeIQx (r = 0.35, P < 0.01), and the molar ratio of creatin(in)e to glucose, respectively. Harman as co-mutagens was linearly correlated to the concentration of glucose (r = 0.65, P < 0.001). By contrast, norharman was not significant correlated to glucose levels.

Evaluation of maillard reaction variables and their effect on heterocyclic amine formation in chemical model systems.

Heterocyclic amines (HCAs), highly mutagenic and potentially carcinogenic by-products, form during Maillard browning reactions, specifically in muscle-rich foods. Chemical model systems allow examination of in vitro formation of HCAs while eliminating complex matrices of meat. Limited research has evaluated the effects of Maillard reaction parameters on HCA formation. Therefore, 4 essential Maillard variables (precursors molar concentrations, water amount, sugar type, and sugar amounts) were evaluated to optimize a model system for the study of 4 HCAs: 2-amino-3-methylimidazo-[4,5-f]quinoline, 2-amino-3-methylimidazo[4,5-f]quinoxaline, 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline, and 2-amino-3,4,8-trimethyl-imidazo[4,5-f]quinoxaline. Model systems were dissolved in diethylene glycol, heated at 175 °C for 40 min, and separated using reversed-phase liquid chromatography. To define the model system, precursor amounts (threonine and creatinine) were adjusted in molar increments (0.2/0.2, 0.4/0.4, 0.6/0.6, and 0.8/0.8 mmol) and water amounts by percentage (0%, 5%, 10%, and 15%). Sugars (lactose, glucose, galactose, and fructose) were evaluated in several molar amounts proportional to threonine and creatinine (quarter, half, equi, and double). The precursor levels and amounts of sugar were significantly different (P < 0.05) in regards to total HCA formation, with 0.6/0.6/1.2 mmol producing higher levels. Water concentration and sugar type also had a significant effect (P < 0.05), with 5% water and lactose producing higher total HCA amounts. A model system containing threonine (0.6 mmol), creatinine (0.6 mmol), and glucose (1.2 mmol), with 15% water was determined to be the optimal model system with glucose and 15% water being a better representation of meat systems.

Impact of different pan-frying conditions on the formation of heterocyclic aromatic amines and sensory quality in fried bacon.

Heterocyclic aromatic amines (HAAs) are formed in the crust of cooked meat products. Most HAAs are carcinogenic in long-term animal studies. Besides precursors in raw materials, important factors are temperature and heating time. Bacon slices were investigated for concentrations of HAAs after pan-frying under different monitored heating conditions. Two HAAs, MeIQx (2-amino-3,8-dimethylimidazo [4,5-f]quinoxaline) (1.5-5.6ng/g) and PhIP (2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine) (0.1-2.6ng/g), were found in pan-fried bacon slices. The bacon clearly contained higher concentrations of HAAs both with longer frying times and at temperatures of 200-220°C rather than 150-170°C, respectively. A similar continuous increase of the concentrations was observed for norharman (5.0-19.9ng/g) and harman (0.3-1.7ng/g). The sensory evaluation, using a hedonic test design for colour and flavour, of the pan-fried bacon slices resulted in a preferred frying time of 5min at 150-170°C. However, some testers clearly preferred crispy and darker bacon slices containing higher HAA concentrations.

Effect of enhancement on the formation of heterocyclic amines in cooked pork loins: preliminary studies.

Heterocyclic amines (HCAs) which are produced in meats cooked at high temperature a risk factor for certain human cancers. This study evaluated the effect of enhancement on HCA formation in cooked pork loins. Three samples of pork loin were prepared including non-injected loin, 12% water-injected loin, and 12% salt/phosphate injected loin. The HCAs were identified in all samples: PhIP (2-amino-1-methyl-6-phenylimidazo [4,5-b]pyridine), MeIQx (2-amino-3,8-dimethylimidazo [4,5-f]quinoxaline), and DiMeIQx (2-amino-3,4,8-trimethylimidazo [4,5-f]quinoxaline). Injection of salt/phosphate significantly reduced the level of PhIP by 42.7%, MeIQx by 79.0%, and DiMeIQx by 75.0%. Enhancement with water alone did not reduce HCA formation.

Sensitive and selective electrochemical determination of quinoxaline-2-carboxylic acid based on bilayer of novel poly(pyrrole) functional composite using one-step electro-polymerization and molecularly imprinted poly(o-phenylenediamine).

A facile and efficient molecularly imprinted polymer (MIP) recognition element of electrochemical sensor was fabricated by directly electro-polymerizing monomer o-phenylenediamine (oPD) in the presence of template quinoxaline-2-carboxylic acid (QCA), based on one-step controllable electrochemical modification of poly(pyrrole)-graphene oxide-binuclear phthalocyanine cobalt (II) sulphonate (PPY-GO-BiCoPc) functional composite on glassy carbon electrode (GCE). The MIP film coated on PPY-GO-BiCoPc functional composite decorated GCE (MIP/PPY-GO-BiCoPc/GCE) was presented for the first time. The synergistic effect and electro-catalytic activity toward QCA redox of PPY-GO-BiCoPc functional composite were discussed using various contrast tests. Also, the effect of experimental variables on the current response such as, electro-polymerization cycles, template/monomer ratio, elution condition for template removal, pH of the supporting electrolyte and accumulation time, were investigated in detail. Under the optimized conditions, the proposed MIP sensor possessed a fast rebinding dynamics and an excellent recognition capacity to QCA, while the anodic current response of square wave voltammetry (SWV) was well-proportional to the concentration of QCA in the range of 1.0×10(-8)-1.0×10(-4) and 1.0×10(-4)-5.0×10(-4) mol L(-1) with a low detection limit of 2.1 nmol L(-1). The established sensor was applied successfully to determine QCA in commercial pork and chicken muscle samples with acceptable recoveries (91.6-98.2%) and satisfactory precision (1.9-3.5% of SD), demonstrating a promising feature for applying the MIP sensor to the measurement of QCA in real samples.

Estimation of quizalofop ethyl residues in black gram (Vigna mungo L.) by gas liquid chromatography.

Quizalofop ethyl, a phenoxy propionate herbicide is used for post emergence control of annual and perennial grass weeds in broad-leaved crops in India. The experiments were designed to study the harvest time residues of quizalofop ethyl in black gram for two seasons. At harvest time, the residues of quizalofop ethyl on black gram seed, foliage and soil were found to be below the determination limit of 0.01 mg kg(-1) following a single application of the herbicide at 50 and 100 g a.i. ha(-1) for both the periods. Application of the herbicide is quite safe from a consumer and environmental point of view.

Formation and mitigation of heterocyclic aromatic amines in fried pork.

Heterocyclic aromatic amines (HAAs) are potent mutagens and carcinogens generated during the heat processing of meat. HAAs, which are abundant in processed meat products, include 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx), 2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline (4,8-DiMeIQx), and 2-amino-1-methyl-6-phenylimidazo [4,5-b] pyridine (PhIP). The content of these three HAAs in fried pork was determined by LC-MS/MS. The effects of frying time and temperature, sample shape, and addition of antioxidants on the generation of HAAs were investigated. The results show that HAAs were produced during frying, and their levels increased with increasing frying time and temperature. Pork patties had the highest concentration of HAAs compared with pork meatballs and pork strips. The addition of antioxidant of bamboo leaves (AOB), liquorice extract, tea polyphenol, phytic acid and sodium iso-ascorbate to pork before frying had an inhibitory effect on HAA generation, with AOB being the most effective antioxidant. Inhibition levels of nearly 69.73% for MeIQx, 53.59% for 4,8-DiMeIQx and 77.07% for PhIP in fried pork were achieved when the concentrations of AOB added were 0.02, 0.01 and 0.10 g kg⁻¹, respectively.

Pharmacokinetics, protein binding and metabolism of a quinoxaline urea analog as an NF-κB inhibitor in mice and rats by LC-MS/MS.

13-197 is a novel NF-κB inhibitor that shows promising in vitro efficacy data against pancreatic cancer. In this study, we characterized the pharmacokinetics, tissue distribution, protein binding and metabolism of 13-197 in mice and rats. A valid, sensitive and selective LC-MS/MS method was developed. This method was validated for the quantification of 13-197, in the range of 0.1 or 0.2-500 ng/mL in mouse plasma, liver, kidney, lung, heart, spleen, brain, urine and feces. 13-197 has low bioavailability of 3 and 16% in mice and rats, respectively. It has faster absorption in mice with 12-fold shorter Tmax than in rats. Tissue concentrations were 1.3-69.2-fold higher in mice than in rats at 72 h after intravenous administration. 13-197 is well distributed to the peripheral tissues and has relatively high tissue-plasma concentration ratios, ranging from 1.8 to 3634, in both mice and rats. It also demonstrated more than 99% binding to plasma proteins in both mice and rats. Finally, <1% of 13-197 is excreted unchanged in urine and feces, and metabolite profiling studies detected more than 20 metabolites in mouse and rat plasma, urine and feces, which indicates that 13-197 is extensively metabolized and primarily eliminated by metabolism rather than by excretion.

Fatality following a suicidal overdose with varenicline.

The smoking cessation agent varenicline acts as a partial agonist on α(4)ß(2) nicotinic acetylcholine receptors. Although debated, several reports have linked varenicline therapy to an increased risk of suicidal thoughts and/or suicide. In addition, several non-fatal overdose cases have been reported. In this report, we utilised a sample preparation procedure suitable for postmortem samples and gas chromatography coupled to mass spectrometry to analyse samples obtained from a suicidal case in which ingestion of an overdose of varenicline had occurred. Extremely high concentrations of varenicline (>250 ng/ml) were detected in the blood of the deceased, in addition to high concentrations in urine and vitreous humour. To the best of our knowledge, similar high concentrations have not been reported yet. Although, with respect to the mechanism of death in this case, confounding factors were concomitant ethanol consumption and, importantly, potentially fatal hypothermia, this is the first report of a fatality associated with the ingestion of an overdose of varenicline.

Formation of heterocyclic amines during cooking of duck meat.

Heterocyclic amines (HAs) are an important class of food mutagens and carcinogens produced in meat cooked at high temperature. In the present study, the effects of various cooking methods: boiling, microwave cooking, charcoal-grilling, roasting, deep-frying and pan-frying on the formation of HAs in duck breast were studied. The various HAs formed during cooking were isolated by solid-phase extraction and analysed by HPLC. Results showed that both the varieties and contents of HAs and the cooking loss of duck breast increase along with increasing cooking temperature and time. Pan-fried duck breasts contained the highest amount of total HAs, followed by charcoal-grilling, deep-frying, roasting, microwave cooking and boiling. 9H-pyrido[3,4-b]indole (norharman) and 1-methyl-9H-pyrido[3,4-b]indole (harman) were detected in all of the cooked duck meat, with levels in the range of 0.1-33 ng g⁻¹. 2-Amino-1-methyl-6-phenylimidazo[4,5-f]pyridine (PhIP) was formed easily in duck meat cooked by pan-frying and charcoal-grilling in the range of 0.9-17.8 ng g⁻¹. 2-Amino-3-methylimidazo[4,5-f]quinoline (IQ) was identified in duck meat cooked by charcoal-grilling and pan-frying, in the range of 0.4-4.2 ng g⁻¹. 2-Amino-3,8-dimethyl-imidazo[4,5-f]quinoxaline (MeIQx) was detected in amounts below 4.5 ng g⁻¹ in duck meat cooked by charcoal-grilling, roasting, deep-frying and pan-frying. The other HAs were detected in amounts below 10 ng g⁻¹. Colour development increased with cooking temperature, but no correlation with HAs' content was observed.

Development of an on-line molecularly imprinted chemiluminescence sensor for determination of trace olaquindox in chick feeds.

BACKGROUND: Olaquindox, as one of the antimicrobial growth accelerants, is usually used in livestock production to improve feed efficiency. Due to health concerns over possible carcinogenic, mutagenic and photoallergenic effects of olaquindox on animals, the development of simple, rapid and sensitive analytical method for determination of olaquindox is crucial and necessary. RESULTS: In this study, a surface molecularly imprinted polymer was prepared by a molecular imprinting technique in combination with a sol-gel process using activated silica gel as a support material. This imprinted material exhibited with good recognition and selective ability, and fast adsorption-desorption dynamics toward olaquindox. Using it as the recognition element, a new on-line molecularly imprinted solid phase extraction coupled with chemiluminescence sensor for the determination of olaquindox was developed. The factors affecting preconcentration of the analytes and sensitivity of the method were all investigated. Under the optimal condition, the linear range of the calibration graph was between 2 × 10(-8) and 1 × 10(-6) g mL(-1) , and the detection limit of this method was 7 × 10(-9) g mL(-1) . The blank chick feed samples spiked with olaquindox at 0.3, 0.9 and 1.5 µg g(-1) levels were extracted and determined by this presented method with recoveries ranging from 87% to 94%. This method was validated by high-performance liquid chromatography and the results correlated well with those obtained by both methods. Moreover, this method was quantitatively analysed with two contaminated chick feed samples. CONCLUSION: This study will provide a sensitive and fast method for the monitoring of olaquindox residues in foods.

Plant extracts, spices, and essential oils inactivate Escherichia coli O157:H7 and reduce formation of potentially carcinogenic heterocyclic amines in cooked beef patties.

Meats need to be heated to inactivate foodborne pathogens such as Escherichia coli O157:H7. High-temperature treatment used to prepare well-done meats increases the formation of carcinogenic heterocyclic amines (HCAs). We evaluated the ability of plant extracts, spices, and essential oils to simultaneously inactivate E. coli O157:H7 and suppress HCA formation in heated hamburger patties. Ground beef with added antimicrobials was inoculated with E. coli O157:H7 (10(7) CFU/g). Patties were cooked to reach 45 °C at the geometric center, flipped, and cooked for 5 min. Samples were then taken for microbiological and mass spectrometry analysis of HCAs. Some compounds were inhibitory only against E. coli or HCA formation, while some others inhibited both. Addition of 5% olive or apple skin extracts reduced E. coli O157:H7 populations to below the detection limit and by 1.6 log CFU/g, respectively. Similarly, 1% lemongrass oil reduced E. coli O157:H7 to below detection limits, while clove bud oil reduced the pathogen by 1.6 log CFU/g. The major heterocyclic amines 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) and 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) were concurrently reduced with the addition of olive extract by 79.5% and 84.3% and with apple extract by 76.1% and 82.1%, respectively. Similar results were observed with clove bud oil: MeIQx and PhIP were reduced by 35% and 52.1%, respectively. Addition of onion powder decreased formation of PhIP by 94.3%. These results suggest that edible natural plant compounds have the potential to prevent foodborne infections as well as carcinogenesis in humans consuming heat-processed meat products.

Occurrence of heterocyclic amines in cooked meat products.

Heterocyclic amines (HCAs), potent mutagens and a risk factor for human cancers, are produced in meats cooked at high temperature. The aim of this study was to determine the HCA content in cooked meat products (beef, chicken, pork, fish) prepared by various cooking methods (pan frying, oven broiling, and oven baking at 170 to 230°C) that are preferred by U.S. meat consumers. The primary HCAs in these samples were PhIP (2-amino-1-methyl-6-phenylimidazo [4,5-b]pyridine) (1.49-10.89ng/g), MeIQx (2-amino-3,8-dimethylimidazo [4,5-f]quinoxaline) (not detected-4.0ng/g), and DiMeIQx (2-amino-3,4,8-trimethyl-imidazo [4,5-f]quinoxaline) (not detected-3.57ng/g). Type and content of HCAs in cooked meat samples were highly dependent on cooking conditions. The total HCA content in well-done meat was 3.5 times higher than that of medium-rare meat. Fried pork (13.91ng/g) had higher levels of total HCAs than fried beef (8.92ng/g) and fried chicken (7.00ng/g). Among the samples, fried bacon contained the highest total HCA content (17.59ng/g).

[Simultaneous determination of 9 heterocyclic aromatic amine in poultry products by solid-phase extraction-high performance liquid chromatography].

A method was developed for the simultaneous determination of 9 heterocyclic aromatic amines (HAAs) including 2-amino-3-methylimidazo[4,5-f] quinoline (IQ), 2-amino-3,4-dimethylimidazo[4, 5-f] quinoline (MeIQ), 2-amino-3, 8-dimethylimidazo [4, 5-f] quinoxaline (MeIQx), 2-amino-3, 4, 8-trimethyl-imidazo [4,5-f quinoxaline (4,8-DiMeIQx), 2-amino-1-methyl-6-phenylimidazo [4,5-b] pyridine (PhIP), 3-amino-1 -methyl-5H-pyrido [4, 3-b] indole (Trp-p-2), 3-amino-1, 4-dimethyl-5H-pyrido [4,3-b] indole (Trp-p-1), 9H-pyrido [3,4-b] indole (Norharman), 1-methyl-9H-pyrido 3, 4-b] indole (Harman)) in poultry products using solid-phase extraction-high performance liquid chromatography (SPE-HPLC). The performance of 3 different organic extraction solutions, 2 solid phase extraction (SPE) procedures, three different reversed-phase columns and five different mobile phases were tested for optimizing separation conditions of the 9 HAAs from poultry products. In the end, ethyl acetate was selected as the extraction solution, and the extract was purified with propylsulfonic acid silica (PRS) and C18 SPE columns. The analysis was performed on a TSK-gel ODS-80TM column using a gradient elution with the mobile phases of 0.05 mol/L aqueous acetic acid-ammonium acetate buffer (pH 3.4) and acetonitrile. The results showed that the average recoveries (n = 6) of the 9 HAAs spiked in meat samples at 3 levels ranged from 60.47% to 90.55% with the relative standard deviations (RSDs) between 0.49% and 9.74%, and the limits of detection (LODs, S/N = 3) were in the range of 0.1 - 3.6 microg/kg. The method is simple, rapid, accurate and sensitive enough for the analysis of HAAs in poultry products.