Arsenic and lead residues in carrots from foliar applications of monosodium methanearsonate (MSMA): A comparison between mineral and organic soils, or from soil residues

Carrot roots may absorb arsenic residues when grown in soil that has been treated previously with arsenical pesticides. Arsenic residues in crops also may result from the inappropriate application of post-emergence arsenical herbicides. To compare potential sources of arsenic residues, carrots were planted in mineral or organic soil and treated post-emergence with the herbicide monosodium methanearsonate (MSMA) at 0, 0.56, 1.12, 2.24, 4.48, or 8.96 kg ha^-1. Arsenic concentration in all plant parts declined between 30 days before harvest and harvest. Arsenic concentration in peeled carrot roots ranged from less than the limit of detection (LOD) for untreated carrots to 0.963 mg kg^-1 (fresh weight) at harvest for carrots treated with 8.96 kg ha^-1 MSMA. In another study, carrots were grown in a greenhouse in soil collected from an old orchard site that had been sprayed with lead arsenate for many years. The old orchard site soil had an arsenic level of 110 mg kg^-1, and similar non-orchard soil had an arsenic level of 1.97 mg kg^-1. All carrot plant segments from plants grown in old orchard soil had higher arsenic concentrations than those from non-orchard soil. Peeled carrot roots from non-orchard soil contained 0.034 mg kg^-1 arsenic, while the peeled roots from old orchard soil had 0.135 mg kg^-1. Old orchard soil had a lead level of 496 mg kg^-1, compared with 6.52 mg kg^-1 for non-orchard soil. Peeled carrot roots from old orchard soil contained 0.885 mg kg^-1 lead, and peeled roots from non-orchard soil contained 0.147 mg kg^-1 lead.     

Development and validation of an analytical method for total amitraz in fruit and honey with quantification by gas chromatography-mass spectrometry

The EU maximum residue limit (MRL) definition for amitraz is 'the sum of amitraz plus all its metabolites containing the 2,4-aniline moiety, expressed as amitraz'. A rapid and sensitive method has been developed and validated in-house for the determination of total amitraz in pears, strawberries, oranges and honey. Samples were hydrolysed (under acidic followed by alkaline conditions) to convert amitraz to 2,4-dimethyaniline, which was then partitioned into 2,2,4-trimethylpentane prior to quantification by gas chromatography-mass spectrometry. The method was validated at 0.02 and 0.1 mg kg^-1 amitraz (well below MRL requirements) with a lowest calibrated level (LCL) for 2,4-dimethylaniline of 0.002 mg kg^-1 (equivalent to 0.0024 mg kg^-1 amitraz). A single partition step yielded recoveries of ∼60% (with % CV values in the range 3.3-8.2), which is satisfactory for screening purposes. A second partition increased recoveries by 10-20%, making the method suitable for the quantification of residues.     

Monitoring of pesticide residues in apples, lettuce and potato of the Slovene origin, 2001-04

Apples, lettuce and potatoes (404 samples) produced in the Republic of Slovenia were analysed for pesticide residues at the Agricultural Institute of Slovenia, Ljubljana, in 2001-04. Sampling from eight agricultural production areas was performed at market producers at the harvesting of products or in storehouses after the pre-harvest interval of plant protection products used. Samples exceeding the maximum residue levels were the following: three apple samples (2.0%) containing 0.33-2.24 mg kg^-1 (phosalone and tolylfluanid), three lettuce samples (3.1%) containing 0.14-6.36 mg kg^-1 (dimethoate, dithiocarbamates and metalaxyl) and 36 potato samples (23.1%) containing 0.06-0.51 mg kg^-1 (dithiocarbamates). Residues of two or more active substances were found in 73 apple samples (48.3%), of which the maximum residue limit (MRL) was exceeded by three samples (2.0%) with the values ranging from 0.33 to 2.24 mg kg^-1, and nine lettuce samples (9.3%), for which the MRL was exceeded by three samples (3.1%) with values from 0.14 to 6.36 mg kg^-1. In potato samples, only residues of dithiocarbamates or no residues at all were found. Residues of the dithiocarbamate group were the most frequently found, i.e. in 66 apple samples (43.7%), 30 lettuce samples (30.9%) and 38 potato samples (24.4%).     

Determination of triazamate in apples, peas and Brussels sprouts using high-performance liquid chromatography with tandem mass spectrometry

A rapid method was developed to allow the analysis of triazamate and the hydrolysis product triazamate acid in apples, peas and Brussels sprouts. The procedure was based on acidified methanol extraction with quantification by liquid chromatography coupled with tandem mass spectrometry detection. The detection limit, based on the lowest calibration level, was 0.005 mg kg^-1. The method was validated at 0.05 and 0.01 mg kg^-1, and was used for screening of triazamate acid in the surveillance of apples as part of the UK pesticide monitoring programme. Calibrations were linear over the range 0.004-0.080 µg ml^-1 (equivalent to 0.005-0.11 mg kg^-1), with a minimum correlation coefficient of 0.95. The detection response showed some matrix-dependent variation. Mean recoveries were in the range 70-108% with associated per cent coefficient of variations of less than 20%.     

An intercomparison study of the determination of glyphosate, chlormequat and mepiquat residues in wheat

An intercomparison study of the determinations of glyphosate, chlormequat and mepiquat residues in cereals was performed. Four samples comprising one blank, two incurred and one spiked sample were sent to six participating laboratories. For glyphosate, two laboratories reported considerably lower results than the other four. One of the two laboratories with low results also reported low recoveries. The results of a sample spiked with 0.80 mg kg^-1 glyphosate and an incurred sample, ranged from 0.23-0.87 mg kg^-1 and 0.11-0.25 mg kg^-1 respectively. The strong correlation between the two samples (r² = 0.95) indicates a systematic between-laboratory variation. Several different principles were used for the analysis of glyphosate using different clean-up techniques and GC/MS, HPLC-fluorescence or LC/MS for detection. The results of the chlormequat residues showed more consistency. All but one laboratory obtained comparable results. However the correlation between the results for the sample spiked with 0.38 mg kg^-1 (range: 0.26-0.65 mg kg^-1) and the incurred samples (range: 0.19-0.45 and 0.15-0.23 mg kg^-1, respectively) again showed a strong correlation (r² = 0.99 and 0.88) indicating a systematic component. For mepiquat, results above the limit of quantification were only reported for the spiked sample. The results ranged from 0.29-0.92 mg kg^-1 (spiked concentration = 0.38 mg kg^-1). Three laboratories had results that deviated less than 25% from the fortified concentration. Two laboratories reported results 38% and 141% above the fortified concentration, respectively.     

Residues of the fungicide famoxadone in grapes and its fate during wine production

Famoxadone is a recently applied fungicide to vines that belongs to the oxazolidinedione family. The fate of famoxadone was studied by considering the decay ratio of this fungicide during the maturation of grapes and wine production. The main factors affecting the presence of fungicide residues such as fruit growth, photodegradation, evaporation, thermodegradation and co-distillation were studied with model systems. An experimental field was treated with a commercial product containing famoxadone at the recommended dose. After this application, residues of famoxadone were found in grapes at 0.27 ± 0.06 mg kg^-1. In this field experiment, the half-life (t_1/2;) of famoxadone, which is described by pseudo-first-order kinetics (R² = 0.74), was 18 ± 6 days, resulting from the photodegradation. The famoxadone residue levels in grapes were below the established maximum residues level for Europe (2 mg kg^-1), whilst levels in wine, carried out with and without maceration, were below the calculated limit of detection of the method.     

Levels of eight trace elements in edible mushrooms from a rural area

Eight trace elements were determined using ICP-MS in 78 fruiting body samples of 22 edible mushroom species. The mushrooms were collected from four sites in a rural area, unpolluted by human activity. Median values (dry matter) were as follows: Arsenic (As) 1.45 mg kg^-1, barium (Ba) 1.41 mg kg^-1, cobalt (Co) 0.28 mg kg^-1, copper (Cu) 47.0 mg kg^-1, rubidium (Rb) 130 mg kg^-1, silver (Ag) 2.95 mg kg^-1, thallium (Tl) 0.02 mg kg^-1 and vanadium (V) 0.25 mg kg^-1. Higher trace element accumulation was observed in samples of Macrolepiota procera, Macrolepiota rhacodes, Lycoperdon perlatum, Lycoperdon gigantea and Xerocomus chrysenteron for As and Cu, and in samples of Cantharellus cibarius and of genera Boletus and Suillus for Rb.     

Intake and risk assessment of nitrate and nitrite from New Zealand foods and drinking water

Exposure to excess nitrite is a potential health risk for humans. One hundred meat and processed foods and 100 vegetable samples purchased from New Zealand retail outlets were prepared as for consumption and analysed for nitrite and nitrate concentration using a standard, validated methodology. Nitrate concentrations ranged from less than the limit of detection (LOD = 5 mg kg^-1) in cheddar cheese and cream cheese-based dips to 3420 mg kg^-1 in lettuce. Nitrite was detected in half the processed foods and meats analysed (levels up to 119 mg kg^-1), but detected in only one vegetable sample above the LOD (broccoli at 27 mg kg^-1 nitrite). Concentration data were combined with 24 h dietary recall information to generate 4398 individual adult daily exposure scenarios for exogenous nitrite and nitrate including a contribution from water assessed from 1021 drinking water samples. The mean adult daily intake of exogenous nitrate and nitrite from food and water combined was 16 and 13% of the Acceptable Daily Intake (ADI), respectively, and therefore should not pose a health risk for the average consumer. A maximally exposed New Zealand adult is estimated to have an intake of up to seven times the ADI for nitrate. When the endogenous conversion of nitrate to nitrite is taken into account, approximately 10% of people with an average rate of conversion and half of all people with a high rate of conversion are estimated to exceed the ADI. Either the ADI is inappropriate and needs to be re-evaluated, or those individuals who have a high rate of conversion of nitrate to nitrite are at risk to adverse effects of nitrite exposure.     

Toxic and essential metals in liver, kidney and muscle of pigs at slaughter in Galicia, north-west Spain

The aims of the study were to evaluate toxic and essential metal concentrations in meat and offal from pigs in north-west Spain to compare these with reported metal concentrations in pigs in other countries and in cattle in this region, and to relate the observed concentrations to maximum acceptable concentrations. Samples from 63 pigs aged 6 months were randomly collected at slaughter. After acid digestion, levels of metals were determined by ICP-OES and ICP-MS. As regards the toxic metals, mean concentrations in liver, kidney and muscle were 0.073, 0.308 and 0.009 mg kg^-1 fresh weight for cadmium, 0.004, 0.008 and 0.003 mg kg^-1 for lead, 0.013, 0.011 and 0.003 mg kg^-1 for arsenic, and 0.001, 0.002 and 0.001 mg kg^-1 for mercury. These concentrations can be considered low, and in general similar to those reported in similar studies in recent years. In addition, maximum admissible concentrations established by the European Union were not exceeded in any sample. As regards the essential metals, concentrations in liver, kidney and muscle were 14.9, 5.63 and 6.85 mg kg^-1 for copper, 81.3, 28.9 and 42.5 mg kg^-1 for zinc, 195, 51.6 and 26.5 mg kg^-1 for iron; 1.17, 2.51 and 0.656 mg kg^-1 for selenium, 3.32, 1.56 and 1.01 mg kg^-1 for manganese, 0.023, 0.027 and 0.003 mg kg^-1 for cobalt, 0.120, 0.077 and 0.131 mg kg^-1 for chromium, 0.009, 0.027 and 0.026 mg kg^-1 for nickel, and 1.62, 0.683 and 0.140 mg kg^-1 for molybdenum. These concentrations are all within the accepted adequate-safe ranges for this animal species, and in general are in line with those previously reported in the literature.     

Validation of an analytical method for the determination of spiramycin, virginiamycin and tylosin in feeding-stuffs by thin-layer chromatography and bio-autography

An inter-laboratory validation was carried out to determine the performance characteristics of an analytical method based on thin-layer chromatography (TLC) coupled to microbiological detection (bio-autography) for screening feed samples for the presence of spiramycin, tylosin and virginiamycin. Twenty-four samples including blank samples and samples with concentrations of the target analytes ranging between 1 and 5 mg kg^-1 (expressed in microbiological activity) were analysed by seven laboratories participating in the study. The required detection limit was 1 mg kg^-1 (expressed in microbiological activity). For spiramycin, acceptable values for the sensitivity (at least 95%) indicating the rate of correct positive results were obtained for samples containing this substance at or above 2 mg kg^-1, whereas at 1 mg kg^-1, the sensitivity rate dropped to about 70%. Therefore, it was concluded that the detection limit was 2 mg kg^-1. For tylosin and virginiamycin, acceptable values of the sensitivity were obtained for all concentrations including 1 mg kg^-1. Therefore, the method fulfils the criterion regarding the required sensitivity at the target detection limit for tylosin and virginiamycin.     

Evaluation of large volume-difficult matrix introduction-gas chromatography-time of flight-mass spectrometry (LV-DMI-GC-TOF-MS) for the determination of pesticides in fruit-based baby foods

The European Union Baby Food Directive (1999/39/EC), which came into force on 1 July 2002, set legal maximum residue levels at 0.01 mg kg^-1 for all pesticides in baby foods. The combination of large volume-difficult matrix introduction (LV-DMI) with gas chromatography-time of flight-mass spectrometry (GC-TOF-MS), described herein, provides the analyst with a simple but rapid alternative GC-MS technique for the multiresidue analysis of pesticides in fruit-based baby foods. Samples were extracted with ethyl acetate in the presence of Na₂SO₄ and NaHCO₃ and the crude extracts were analysed directly using LV-DMI-GC-TOF-MS. The best overall results (98 pesticides quantified satisfactorily at a spiking level of 0.01 mg kg^-1) were obtained by analysis of concentrated extracts (2.5 g crop ml^-1) using a 30-m column, with a chromatographic run time of 25 min. A good signal-to-noise ratio was obtained at the lowest calibrated level (0.0125 μg ml^-1), with excellent linearity achieved over the range 0.0125-0.25 μg ml^-1 (equivalent to 0.005-0.1 mg kg^-1). Average recoveries for the analysis of five replicate determinations at a spiking level of 0.01 mg kg^-1 were between 79 and 114% with relative standard derivations generally less than 20%.     

A sulfadimidine model to evaluate pharmacokinetics and residues at various concentrations in laying hen

Low level intake of drugs from the ingestion of contaminated feed may lead to residue problems in food animals. Sulfadimidine (SDD) was used as a model to determine the residue risk at various doses in laying hens. The drug was administered as a single intravenous injection (100 mg kg^-1 body weight, BW), as a single oral dose (100, 30, 10, 3, 1 mg kg^-1 BW) and via medicated feed for 7 consecutive days (30, 10, 3 mg kg^-1 BW). Drug levels were determined with HPLC-UV for plasma, yolk and albumen. Pharmacokinetic values, which were calculated using a first-order one-compartment model, residue levels and transfer rates into the eggs were found to be dose-dependent. Even low doses of 3 and 1 mg kg^-1 BW resulted in measurable residues in yolk and albumen 1 day after a single oral administration. After ingestion of medicated feed at 3 mg kg^-1 BW, mean drug levels at 0.14 ± 0.01 µg g^-1 were found in albumen and at 0.09 ± 0.01 µg ml^-1 in plasma. Generally, the residue levels in albumen and plasma were higher than in yolk. These findings demonstrate a residue risk for the consumer even after low level intake of drugs.     

Method of test and survey of caprolactam migration into foods packaged in nylon-6

An analytical method for the determination of the nylon-6 monomer caprolactam in foods is described. The foodstuff was extracted with ethanol : water (1:2) containing capryllactam as internal standard and the extract was defatted using hexane. The extract was analysed by liquid chromatography coupled with mass spectrometry. The test method was calibrated down to 0.7 mg kg^-1. The repeatability of the method was good, with a relative standard deviation of 9% at the 15 mg kg^-1 level. The method was demonstrated to be accurate in an independent external check sample exercise. The new method was applied to the analysis of 50 retail foodstuffs packaged in nylon-6. Caprolactam was detected and confirmed in nine of the 50 food samples, in the range 2.8-13 mg kg^-1. The presence of caprolactam was indicated in a further 15 samples, in the range 0.8-11 mg kg^-1, but these samples did not meet all of the five confirmation criteria applied. All migration levels (both confirmed and unconfirmed) were below the European specific migration limit for caprolactam, which is 15 mg kg^-1. The average migration for all 50 samples, setting non-detectables at half the limit of detection, was 2.6 mg kg^-1 with a standard deviation of 3.1 mg kg^-1 (n = 50). All samples found to contain detectable levels of caprolactam migration were for applications involving heating the food in the packaging. They were packs of, for example, sausage meat for which the food would have been heat processed in the nylon casing, or they were nylon pouches for heating foods by boiling, microwaving or roasting.     

Study on the effect of grain storage and processing on deltamethrin residues in post-harvest treated wheat with regard to baby-food safety requirements

The effects of storage intervals and of milling procedures on dissipation of deltamethrin residues in post-harvest treated wheat grain were studied with the aim to obtain scientific data on compliance of the processed products with the safety requirements concerning baby foods. The insecticide formulation was applied on stored wheat at a recommended rate of active ingredient of 0.5 mg kg^-1 and at a higher rate of 4 mg kg^-1, performing the highest protective effect. The dissipation of residues and their distribution in different fractions of the milled grain were studied after various storage intervals, from 7 to 270 days after treatment. Eight fractions—bran, semolina, three types of groats, and three types of flour—were collected after milling of grain and analysed for determination of pesticide residues. The residues were determined by gas chromatography characterized by the limit of determination of 0.005 mg kg^-1, low enough for enforcement of the maximum residue level of 0.01 mg kg^-1 established by the European Commission Directive for any pesticide in cereal-based foods. Deltamethrin applied post-harvest on wheat as grain protectant was distinguished by low rate of degradation on the grain under practical storage conditions. One hundred and eighty days after treatment at an application rate of 0.5 mg kg^-1, the residues were between 0.03 and 0.2 mg kg^-1 in the various types of flour. Two hundred and seventy days after treatment at a rate of 4 mg kg^-1, the residues in the flour were in the range of 0.4-1.5 mg kg^-1.     

Residues of azoxystrobin, fenhexamid and pyrimethanil in strawberry following field treatments and the effect of domestic washing

Residues of the pesticides azoxystrobin, fenhexamid and pyrimethanil were determined in strawberry after field treatment. The effect of 'home' washing with tap water and a commercially available vegetable detergent on residue levels was also studied. After treatment, azoxystrobin and pyrimethanil residues on strawberry were on average 0.55 and 2.98 mg kg^-1, respectively, values below the maximum residue level (MRL) fixed by the European Union (2.0 and 5 mg kg^-1, respectively), while fenhexamid residues were on average 2.99 mg kg^-1, which is very close to the MRL of 3.0 mg kg^-1, but some samples were over the MRL. Thereafter, all residues declined, with a half-life of about 8 days (azoxystrobin and fenhexamid) and 4.8 days (pyrimethanil). Washing the fruit with tap water reduced the residues of azoxystrobin and fenhexamid but did not affect pyrimethanil residues. Finally, when fruits were washed with a commercial detergent, greater amounts were removed (about 45% of azoxystrobin and pyrimethanil and 60% of fenhexamid).     

Estimated intake of intense sweeteners from non-alcoholic beverages in Denmark

In 1999, 116 samples of non-alcoholic beverages were analysed for the intense sweeteners cyclamate, acesulfame-K, aspartame and saccharin. High contents of cyclamate close to the maximum permitted level in 1999 of 400 mg l^-1 were found in many soft drinks. The estimated intake of the sweeteners was calculated using the Danish Dietary Survey based on 3098 persons aged 1-80 years. The estimated intake with 90th percentiles of 0.7, 4.0 and 0.2 mg kg^-1 body weight (bw) day^-1 for acesulfame-K, aspartame and saccharin, respectively, was much lower than the acceptable daily intake (ADI) values of 15, 40 and 2.5 mg kg^-1 bw day^-1 for acesulfame-K, aspartame and saccharin, respectively. However, the 90th percentile of the estimated cyclamate intake in 1-3 year olds was close to the ADI value of 7 mg kg^-1 bw day^-1; and the 99th percentile in the 1-10 year olds far exceeded the ADI value. Boys aged 7-10 years had a significantly higher estimated intake of cyclamate than girls. The 90th percentile for the whole population was 1.8 mg kg^-1 bw day^-1. After the reduction in the maximum permitted level in the European Union in 2004 from 400 to 250 mg cyclamate l^-1, the exposure in Denmark can also be expected to be reduced. A new investigation in 2007 should demonstrate whether the problem with high cyclamate intake is now solved.     

Nitrates and nitrites in vegetables and vegetable-based products and their intakes by the Estonian population

The content of nitrates were determined in 1349 samples of vegetables and ready-made food in 2003-2004 as a part of the Estonian food safety monitoring programme and the Estonian Science Foundation grant research activities. The results of manufacturers' analyses carried out for internal monitoring were included in the study. The highest mean values of nitrates were detected in dill, spinach, lettuce and beetroot. The mean concentrations were 2936, 2508, 2167 and 1446 mg kg^-1, respectively. The content of nitrites in samples was lower than 5 mg kg^-1. In total, the mean intake of nitrates by the Estonian population was 58 mg day^-1. The mean content of nitrates in vegetable-based infant foods of Estonian origin was 88 mg kg^-1. The average daily intake of nitrates by children in the age group of 4-6 years was 30 mg. The infants' average daily intake of nitrates from consumption of vegetable-based foods was 7.8 mg.     

Usage of saccharin in food products and its intake by the population of Lucknow, India

A survey of the usage patterns of the artificial sweetener, saccharin, in edible products and a study of its intake pattern in different population groups has been carried out. Of the different edible commodities, ice candy (87 samples) and crushed ice (14 samples), commonly consumed by children, and pan masala (16 samples) and pan flavourings (10 samples), consumed by the habitual population, were collected from different areas of Lucknow, India. Saccharin was extracted from the samples according to an AOAC method and analysed by HPLC. The consumption pattern of ice candy and crushed ice was determined for 6-20 year olds from a household dietary survey using the food frequency recall method (414 families having 1039 subjects). The consumption of pan masala and pan was assessed by a survey of habitual adult consumers comprising 782 and 1141 subjects, respectively. The average and maximum amounts of saccharin in pan masala samples were 12 750 and 24 300 mg kg^-1, respectively, which are 1.6- and 3-fold higher than the maximum permitted levels allowed under Prevention of Food Adulteration (PFA) Act of India. In pan flavourings, the average and maximum amount of saccharin was 12.2 and 20.1%, i.e. 1.52- and 2.5-fold higher than the permissible limits of the PFA Act. The samples of ice candy and crushed ice showed average and maximum levels of 200 and 700 mg kg^-1 and 280 and 460 mg kg^-1, respectively. The average intake of saccharin through ice candy and crushed ice was less than 21% of the acceptable daily intake (ADI) (5 mg kg^-1 body weight (bw) day^-1). However, the maximum intake of saccharin, especially in the 6-10-year age group, contributed 57 and 68% of the ADI through ice candy and crushed ice, respectively. Maximum consumption of saccharin in all the age groups, if consuming both ice candy and crushed ice, results in exceeding the ADI by 54% for subjects in the 6-10-year age group. Hence, the 6-10-year age group population may be at risk of exceeding the ADI for saccharin. The average and maximum theoretical daily intake of saccharin through pan masala alone was 1.84 and 13.33 mg kg^-1 bw day^-1, contributing 37 and 267% of the ADI, whereas the estimated (maximum) daily intake was 810% of the ADI. The estimated maximum daily intake (EDI) of saccharin through pan was 6.87 mg kg^-1 bw day^-1, which was 137% of the ADI. Thus, individuals in the maximum consumption group for pan masala or pan may be susceptible to toxic effects of saccharin, including bladder distention, elevated urine osmolality and bladder cancer.     

Determination of ochratoxin A in virgin olive oils of Greek origin by immunoaffinity column clean-up and high-performance liquid chromatography

An improved specific analytical method for ochratoxin A (OTA) determination in olive oil is described, using a methanolic-aqueous extraction, an immunoaffinity column clean up step and high-pressure liquid chromatography with fluorescence detection. The mean recovery was found at 108% (relative standard deviation, RSD = 4.7%) and the detection limit (DL) was estimated at 4.6 ng kg^-1. Along with OTA, aflatoxin B₁ (AFB₁) was determined using the same extract. The recovery factor was 84.8% (RSD = 17.8%) and the DL was 56 ng kg^-1 olive oil. Both determinations were applied in 50 samples of olive oil originated from representative regions of Greece. Results revealed the presence of OTA in 88% of samples tested (n = 44, mean 267 ng kg^-1). Among them, 10 were contaminated with more than 500 ng kg^-1 (median 568 ng kg^-1), 10 with 200-500 ng kg^-1 (median 260 ng kg^-1), 15 with 100-200 ng kg^-1 (median 140 ng kg^-1), nine with DL-100 (median 60 ng kg^-1) and in six samples, OTA was not detectable. Interestingly, most contaminated samples were from Southern Greece. Results of AFB₁ determination showed the presence of aflatoxin B₁ (60 ng kg^-1) in only one olive oil sample also from Southern Greece. The levels of OTA found in Greek olive oil were relatively low as compared with other commodities such as cereals or wine reported in the literature.     

Determination of ethylenethiourea (ETU) and propylenethiourea (PTU) in foods by high performance liquid chromatography-atmospheric pressure chemical ionisation-medium-resolution mass spectrometry

A robust and sensitive method for the determination of ethylenethiourea (ETU) and iso-propylenethiourea (i-PTU) in foods is reported. ETU and i-PTU were extracted by blending with dichloromethane (DCM) in the presence of sodium sulphate, sodium carbonate, thiourea and ascorbic acid. ²H₄-ETU and n-PTU were used as internal standards. After filtration the DCM was removed by rotary evaporation and the extract re-dissolved in water before analysis by reversed-phase liquid chromatography with detection by atmospheric pressure chemical ionization-mass spectrometry using a double focusing mass spectrometer at a resolution of 5000. Mean recoveries of ETU and i-PTU from fruit-based, cereal-based and meat-based infant foods, potato chips and tinned potatos at 0.01 mg kg^-1 and from pizza and yoghurt at 0.02-0.1 mg kg^-1 were 95% and 97% respectively. Precision, including both repeatability and internal reproducibility, was in the range of 3.1-13.1%.