Determination of residues of oxolinic acid and flumequine in freeze-dried salmon muscle and skin by HPLC with fluorescence detection

A procedure for the determination of residues of oxolinic acid (OA) and flumequine (FLU) in freeze-dried salmon muscle with attached skin, using reversed-phase high-performance liquid chromatography, is described. OA and FLU were extracted by a solid-liquid extraction procedure: after addition of hydrochloric acid, extraction used successively ethyl acetate, sodium hydroxide and chloroform. Liquid chromatography was performed on a 5 μm PuroSpher RP-18E ® cartridge using acetonitrile and 0.02 M aqueous orthophosphoric acid solution as mobile phase, with fluorescence detection. The performance of the method was established by spiking tissues with OA and FLU before the freeze-drying step. The method was linear over the concentration range 50-2000 ng/g freeze-dried tissue. Limits of detection and quantitation were 3.2 and 16 ng/g wet weight tissue respectively both for OA and FLU. Mean extraction recoveries of OA and FLU from freeze-dried tissue were 85.5 and 85.2% respectively. The method is suitable as a regulatory one for determination of residues of OA and FLU in freeze-dried salmon tissue.     

Bisphenol A migration from cans containing coffee and caffeine

This study was conducted to reconfirm the possibility and level of bisphenol A (BPA) migration from cans containing coffee and test the relationship between caffeine concentration and BPA migration from the can coating. BPA migration from cans containing decaffeinated and non-decaffeinated instant coffee averaged 66.2 and 84.0 ng ml -1 , respectively. In our study, the possibility of BPA migration from cans containing coffee after processing was found. In addition, the more caffeine content in the water solution of caffeine increased, the more BPA migration grew. This means that caffeine can have an effect on BPA migration from the can coating.     

Linking extraction and purification of maize samples for fumonisin analysis

Fumonisins are produced by several fungal species that are common contaminants of maize, The most abundant naturally occurring fumonisin, fumonisin B₁ (FB₁), has been shown to induce several animal disease syndromes. The development of analytical methods is therefore important. A new method is described that integrates extraction and purification of maize samples in one step. It efficiency is compared against wellknown methods, and shows similar results for naturally contaminated maize. It is concluded that the proposed method can be applied to fumonisin B₁ and fumonisin B₂ (FB₂) analysis in maize at least within the con2 centration range found.     

Validation of HPLC method of analysis of tetracycline residues in eggs and broiler meat and its application to a feeding trial

HPLC with ion-pairing chromatography and diodearray detection at 355nm was used to determine tetracycline antibiotics in eggs and broiler meat. The analytical methods were optimized and validated. The mean recovery values for oxytetracycline for eggs and for tetracycline for breast meat were 76% . The withinday precision ranged from 8.0 to 11.8% for oxytetracycline in eggs and from 6.1 to 15.5% for tetracycline in breast meat. The between-day precision was 4.8% and 5.0% respectively for oxytetracycline in eggs and tetracycline in breast meat. The limit of detection and the limit of quantitation for oxytetracycline in eggs were 2.2 and 13.0ng/g respectively. These limits for tetracycline in breast meat were 10.5 and 20.9ng/g respectively. Residue values of tetracycline antibiotics in eggs and broiler meat were determined after oral administration of medicated feed. Medicated feed with 840mg/kg oxytetracycline was provided to laying hens for seven successive days. Two days after the administration was stopped, the mean oxytetracycline residue value in the eggs was already lower than the Maximum Residue Limit (MRL)-level and reached 118ng/g. Broilers were supplied with medicated feed containing 480mg/kg tetracycline for seven successive days. Four days after the administration was stopped, the mean tetracycline residue value in breast meat decreased below the MRL and was 86ng/g.     

Tylosin depletion in edible tissues of turkeys

The depletion of tylosin residues in edible turkey tissues was followed after 3 days of administration of tylosin tartrate at 500 mgl^-1 in drinking water, to 30 turkeys. Immediately after the end of the treatment (day 0) and at day 1, 3, 5 and 10 of withdrawal, six turkeys (three males and three females) per time were sacrificed and samples of edible tissues were collected. Tissue homogenates were extracted, purified and analysed by HPL C according to a method previously published for the analysis of tylosin residues in pig tissues. In all tissues, tylosin residues were already below the detection limits of 50 μg kg^-1 at time zero. However, in several samples of tissues (skin ₊ fat, liver, kidney, muscle), from the six turkeys sacrificed at that time, one peak corresponding to an unknown tylosin equivalent was detected at measurable concentrations. The identification of this unknown compound was performed by L C-MS/MS analysis of the extracts from incurred samples. The mass fragmentation of the compound was consistent with the structure of tylosin D (the alcoholic derivative of tylosin A), the major metabolite of tylosin previously recovered and identified in tissues and/or excreta from treated chickens, cattle and pigs.     

Occurrence of deoxynivalenol (vomitoxin) in processed cereals and pulses in Turkey

The aim was to investigate the occurrence of deoxynivalenol (DON) in cereal and pulse products in Turkey. DON was detected using high-performance liquid chromatography (HPLC) with ultraviolet detection at 220 nm and positive results greater or equal to 0.60 ppm were confirmed by thin layer chromatography (TLC). An acetonitrile-water (21:4 v/v) extract of the sample was cleaned up on a column packed with alumina-Celite-charcoal (0.35 + 0.25 + 0.40 g). The detection limits for DON were 3 ng/injection (0.10 ppm) and 50 ng/spot (0.60 ppm) for HPLC and TLC, respectively. Eighty-three commercially available cereal and pulse product samples collected from markets and street bazaars were analysed. The recovery rates for boiled, pounded wheat and rice spiked with added DON (1 ppm) were 80.9% (SD 8.37, n =5) and 72.3% (3.85, n =5), respectively. DON was detected in six (8.82%) of 68 cereal and in none of 15 pulse products. The maximum detected amount was 2.67 ppm in a corn flour sample.     

Analytical methods for food-contact materials additives in olive oil simulant at sub-mg kg-1 level

Methods of analysis for four additives (two antioxidants, IRGANOX 245 and 1035; an ultraviolet absorber, CHIMMASORB 81; and an optical brightening agent, UVITEX OB) in olive oil are reported. These additives have the potential to migrate from food-contact materials into the European Union fatty food simulant olive oil, which is the most difficult matrix for analysis. The additives were chosen because they differed in their chemically active groups, had different functions within the polymer, have low proposed specific migration limits and are commonly used in food-contact materials such as polystyrenes and polyolefins. The proposed analytical methods for the additives are simple, rapid, inexpensive and also broadly applicable to the aqueous food simulants. All methods were evaluated by constructing calibration curves, measurement of recovery and precision, and determining the limits of detection. Most of the methods involve direct injection of an olive oil solution for high-performance liquid chromatography analysis with ultraviolet-visible or fluorescence detection. The methods allowed establishment of additive stability and measurement of migration of the selected additives into olive oil at different time-temperature conditions used in migration studies into food simulants.     

Occurrence of aflatoxin M1 in Korean dairy products determined by ELISA and HPLC

The occurrence of aflatoxin M₁ (AFM₁)in pasteurized milk and dairy products was investigated by using direct competitive enzyme-linked immunosorbent assay (ELISA) and high-performance liquid chromatography (HPLC). The recoveries of AFM₁ from the samples spiked at levels between 5 and 500 pg/ml were 88.0-106.5% for pasteurized milk and 84.0-94.0% for yoghurt by ELISA. By HPLC, the recoveries were 103-120% for pasteurized milk and 87.0-93.0% for yoghurt. The limits of detection were found to be 2 pg/ml by ELISA and 10 pg/ml by HPLC. Among a total of 180 samples collected in Seoul, Korea, the incidence of AFM₁ in pasteurized milk, infant formula, powdered milk and yoghurt was 76, 85, 75, and 83% , respectively, with a mean concentration of 18, 46, 200, and 29 pg/g, respectively, when determined by ELISA. These results obtained by ELISA were closely related to those by HPLC for AFM₁ (r² = 0.9783).     

Br concentration as an indication of pre-baking bromation of bread products

Br concentration in bread for baked bread products was shown to be linearly proportional to the amount of Br added per kg of flour used to make the product. Br concentration in bread can be used to help identify those bread products with the greatest likelihood of containing bromate residues. Instrumental neutron activation analysis was used to determine Br in test portions of bread products from commercial bakeries, homemade bread, flour, and unbaked dough. High performance liquid chromatography was used to determine the bromate residue in selected test portions.     

Measurement of paralytic shellfish toxins in molluscan extracts: comparison of the microtitre plate saxiphilin and sodium channel radioreceptor assays with mouse bioassay, HPLC analysis and a commercially available cell culture assay

This study compared five methods of measuring paralytic shellfish toxins (PSTs) including the long-used mouse lethality bioassay, a commercially available cell culture test (MIST ® Quantification kit), HPLC analysis, and two newly developed radioreceptor assays utilizing mammalian sodium channels and saxiphilin. Methods were challenged with toxic shellfish extracts prepared according to the AOAC official method. The best correlations between predicted toxicity values being 0.9 or better, were those between HPLC analysis when compared with both radioreceptor assays and the mouse lethality bioassay, as well as that between the saxiphilin and the sodium channel radioreceptor assays. In all cases, statistically significant correlations existed between the toxicity measurements of the same extracts. The ratios between some methods were not unitary as measured by the slopes of the regression lines used for correlation analyses. HPLC analysis predicted more toxicity than all of the bioassays. The saxiphilin assay underestimated toxicity relative to the mouse bioassay, the MIST ® kit determinations and the sodium channel assay. The sodium channel assay predicted there to be less toxicity than the mouse bioassay and the MIST ® kit. Of all of the techniques used, the MIST ® kit correlation with the mouse bioassay was nearest to one. Each method possesses different virtues and it may be that a multi-method approach would harness the benefits of each method for various aspects of a shellfish testing regime.