Development and Validation of a Method for the Determination of Quinolones in Muscle and Eggs by Liquid Chromatography-Tandem Mass Spectrometry

In this study, the development and validation of a multiresidue method for the detection of 11 quinolones (marbofloxacin, norfloxacin, ciprofloxacin, danofloxacin, lomefloxacin, enrofloxacin, sarafloxacin, difloxacin, oxolinic acid, nalidixic acid, flumequine) in muscle and eggs were reported. The method involved an extraction with a methanol/metaphosphoric acid mixture and a clean up by Oasis hydrophilic-lipophilic balance (HLB) cartridge. The validation was performed according to the Commission Decision 2002/657/EC. Linearity, specificity, decision limit (CCα), detection capability (CCβ), recovery, precision (repeatability and within-laboratory reproducibility), and ruggedness were determined. Depending on the analytes, CCα and CCβ ranged from 113 to 234 μg/kg and from 126 to 282 μg/kg in muscle samples, whereas in eggs, these parameters were between 5.6 and 7.4 μg/kg and between 6.1 and 9.8 μg/kg, respectively. In both the examined matrices, the recovery values were always higher than 90 % and precision, calculated as relative standard deviation, was equal to or lower than 16 % for repeatability and 23 % for within-laboratory reproducibility. The described method can be considered adequate for the simultaneous determination and quantification of quinolones in the tested food matrices.     

The UPLC–ESI–QqQLIT–MS/MS method for quantitative determination of phytochemicals in ethanolic extracts of different parts of eight Ficus species: Development and validation

Ficus and validation of the ultra performance liquid chromatography–electrospray ionization hybrid triple quadrupole–linear ion trap–tandem mass spectrometry (UPLC–ESI–QqQ_LIT–MS/MS) method in a multiple-reaction monitoring (MRM) mode for the quantitative determination of 19 phytochemicals. The chromatographic separation of targeted phytochemicals was performed using the Waters ACQUITY UPLC BEH? C18 column (1.7 μm, 2.1 mm × 50 mm) with 0.1% formic acid with water and acetonitrile as a mobile phase at a flow rate of 0.25 mL/min. The validation parameters showed the overall recoveries from 95.78?101.44% (RSD ≤ 3.25%), precision (intra-day: RSD ≤ 2.96%; inter-day: RSD ≤ 2.89%), linearity (R² ≥ 0.9982), limit of detection (8.60 × 10^–10?2.18 × 10^–6 mg/mL), and the limit of quantitation (2.60 × 10^–9–6.63 × 10^–6 mg/mL) in the concentration range from 0.5 to 1000 × 10^–6 mg/mL. This method was successfully applied in ethanolic extracts of different parts (fruits, leaves, and barks) of selected eight Ficus species. Quinic acid was predominant followed by rutin and chlorogenic acid among the studied nineteen phytochemicals. Ficus benjamina showed the maximum total content in fruits and leaves. The UPLC–ESI–QqQ_LIT–MS/MS method combined with principal component analysis (PCA) was successfully used for Ficus species discrimination on the basis of the contents of 15 compounds. The UPLC–ESI–QqQ_LIT–MS/MS method combined with PCA could be used for quality control.     

Simultaneous Determination of Ractopamine,Chloramphenicol, and Zeranols in Animal-Originated Foods by LC-MS/MS Analysis with Immunoaffinity Clean-up Column

A novel analytical method employing immunoaffinity column (IAC) clean-up coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for simultaneous determination of ractopamine, chloramphenicol, and zeranols (α-zearalanol, β-zearalanol, zearalanone, α-zearalenol, β-zearalenol, and zearalenone) in animal-originated foods. The sample was first digested by β-glucuronidase/sulfatase and then extracted with ethyl acetate-diethyl ether (9:1, v/v). The extracted solution was evaporated to dryness and then the residue was dissolved by 2 mL of 50% acetonitrile solution. After filtration, 1 mL filtrate was diluted to 10 mL with PBS. The reconstituted solution was cleaned up with immunoaffinity column and then analyzed by high performance liquid chromatography-tandem mass spectrometry (LC-MS/MS). The established method was shown to be sensitive efficient and reliable as indicated by the linearity (r ² ≥ 0.9994), precision (RSD ≤ 1.7%), average recovery (72.3–103.2%), and the limit of detection (0.05–0.10 μg/kg). The method can be used for determination of trace residues of ractopamine, chloramphenicol, and zeranols in animal-originated foods.     

Simultaneous Determination of Cyadox and Its Metabolites in Chicken Tissues by LC-MS/MS

A specific and sensitive LC-MS/MS method was firstly established for the simultaneous extraction and determination of cyadox and its three main metabolites—1,4-bisdesoxycyadox, 4-desoxycyadox, and quinoxaline-2-carboxylic acid—in chicken muscle, liver, kidney, and fat tissues. Samples were subjected to extraction using ethyl acetate and followed by acetonitrile–chloroform (1:4, v/v) and further purified by Oasis mixed mode anion exchange SPE cartridge. Analysis was performed on a C₁₈ column by detection with MS in multiple-reaction monitoring mode. A gradient elution program with 0.1 % formic acid solution, acetonitrile, and 1 % formic acid (adjusted to pH 8 with ammonia) was performed at a flow rate of 0.2 mL min^?1. The correlation coefficients (r) for each calibration curve are higher than 0.99 within the experimental concentration range. The recoveries of the four target analytes at three spiking levels of 2.5, 25 and 250 μg kg^?1 were between 74.5 and 93.8 %, with relative standard deviations less than 12 %. The decision limits (CCαs) of the four analytes in chicken edible tissues ranged from 0.3 to 1.5 μg kg^?1, and the detection capabilities (CCβs) were below 2.3 μg kg^?1. The developed method demonstrated a satisfactory applicability in incurred chicken tissue samples.     

Verification of 5-Methyltetrahydrofolic Acid in Nutritional Products

A simple method for the verification of supplemental (6R,S)-5-methyl-5,6,7,8-tetrahydrofolic acid, “5-MTHF,” in nutritional products is described. Nutritional product samples are prepared for the liquid chromatographic/fluorescence detection (LC/FLD) determination of 5-MTHF by buffer dilution, 10-min centrifugation, and syringe filtration. Method performance has been defined by assessments of 5-MTHF linearity (r ² averaged 0.9999 ± 0.0001, and all relative calibration errors averaged ≤0.6%, for ten consecutive six-point standard curves), intermediate precision (rsd = 1.1%, n = 9, for three products fortified at ～1.73 μmol/kg = ～795 μg/kg, tested on each of 3 days), accuracy (spike recovery average = 92.8 ± 1.0%, n = 9, for nutritional products spiked with 5-MTHF at ～1.73 μmol/kg, or ～795 μg/kg), and selectivity (absence of interference from reagent blanks, and from four compounds structurally related to 5-MTHF). The 5-MTHF recovery, as % of unheated controls, from a simulated heat treatment (20 min at 120 °C) averaged 99.1 ± 0.6%, n = 4. The limits of 5-MTHF detection (S/N = 3) and quantification (S/N = 10) were experimentally determined to be 10 μg/kg (～0.020 μmol/kg) and 30 μg/kg (～0.060 μmol/kg), respectively (<10× the expected fortification rate). The method provides a simple and inexpensive means for verifying proper fortification, and for assessing the stability to processing and storage conditions, of free 5-MTHF in nutritional products. A finding of interest is the indication that liquid nutritional products may comprise a stable matrix for 5-MTHF fortification.     

Volatile emerging contaminants in melon fruits,analysed by HS-SPME-GC-MS

The aim of this research was to develop and validate a headspace-solid phase micro-extraction–gas chromatography–mass spectrometry (HS-SPME–GC–MS) method for the determination of volatile emerging contaminants in fruit. The method showed good precision (RSD ≤ 14%) and satisfactory recoveries (99.1–101.7%) and LOD and LOQ values ranging between 0.011–0.033 μg kg^?1 and 0.037–0.098 μg kg^?1, respectively. The method was applied to investigate the content of volatile emerging contaminants in two varieties of melon fruit (Cucumis melo L.) cultivated adjoining high-risk areas. Glycol ethers, BHT, BHA and BTEX (benzene, toluene, ethylbenzene and xylene) were determined in melon fruit pulps for the first time, with different sensitivities depending on sample and variety. Although the amount of the volatile contaminants in the melon samples were in the order of µg kg^?1, the safety of vegetable crops cultivated near risk areas should be more widely considered. The results showed that this accurate and reproducible method can be useful for routine safety control of fruits and vegetables.     

Modification of Multiresidue QuEChERS Protocol to Minimize Matrix Effect and Improve Recoveries for Determination of Pesticide Residues in Dried Herbs Followed by GC-MS/MS

An accurate, rapid, and reliable multiresidue QuEChERS method based on gas chromatography coupled with tandem mass spectrometry was developed for the determination of 235 pesticides in challenging, dry, complex herb matrices (Centaurea cyanus L., Matricaria chamomilla L., Thymus vulgaris L.). Sample mass and the type of cleanup sorbent used to estimate the procedure’s effectiveness were optimized. Purification steps with ChloroFiltr, ENVI-Carb, GCB, octadecyl, PSA, and Z-Sep as cleanup sorbents and a step without purification were compared. To minimize the matrix effect and obtain acceptable recoveries for pesticides, 2 g of herb sample and 10 mL acetonitrile, followed by d-SPE cleanup step with a combination of 150 mg PSA/45 mg ENVI-Carb/900 mg MgSO₄, and additionally 50 μL of 5% formic acid and some droplets of dodecane, were needed. Matrix effects for the vast majority of pesticides were reduced (>?20%), showing suppression or enhancement. Most recoveries were in the range of 70–120% (RSD < 18%), reaching the quantification limit of 0.001 to 0.002 mg kg^?1. There was excellent linearity within the range from 0.001 to 2.00 μg mL^?1, and a correlation coefficient higher than 0.999 was obtained. Expanded measurement uncertainty was estimated to be between 4 and 43%. Finally, the developed method was successfully employed to identify and quantify pesticide residues in the analysis of 46 real herb samples.     

Determination of 103 Pesticides and Their Main Metabolites in Animal Origin Food by QuEChERS and Liquid Chromatography–Tandem Mass Spectrometry

A rapid and sensitive analytical multiresidue method has been developed for the simultaneous determination of 103 pesticides (herbicides, insecticides, and fungicides) and 18 metabolites in foods of animal origin using liquid chromatography-tandem with triple quadrupole in dynamic multiple reaction monitoring (DMRM) mode. A modified quick, easy, cheap, effective, rugged, and safe (QuEChERS) sample preparation technique was established, and the efficiency of the dispersive solid-phase extraction (d-SPE) cleanup step was evaluated by comparing the effects of different d-SPE sorbent combinations (primary secondary amine (PSA) + graphitized carbon black (GCB), PSA + C18, C18, and C18 + GCB). The limits of quantification (LOQs) ranged from 1 to 10 μg/kg, and the coefficient of determination (R ²) was ≥0.995 within the calibration linearity range of 0–250 μg/L for all pesticides. The combination of C18 + GCB was validated at two spiking levels (10 and 50 μg/kg) in chicken, fish, pork, and rabbit. Satisfactory recoveries (70–119%) and RSDs ≤17% were achieved for all analytes, except for naptalam (60–69%), pyrimethanil (40–49%), and thiabendazole (62–66%) at 10 μg/kg spiking level. The validated method was successfully applied to the analysis of real samples of food of animal origin.     

Rapid multi-element analysis of Chinese vinegar by sector field inductively coupled plasma mass spectrometry

An analytical method for simultaneous determination of 20 trace elements in vinegar including Na, Mg, K, Ca, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Sr, Mo, Cd, Sn, Sb, Ba and Pb by sector field inductively coupled plasma mass spectrometry (SF-ICP-MS) with microwave digestion has been established. Sample first underwent microwave digestion with HNO₃ + H₂O₂ followed by dilution with ultrapure water, and then, the as-obtained solution was analyzed directly by SF-ICP-MS. The matrix effects were studied in details and corrected by Sc, In and Re as the internal standard elements. Data accuracy was improved by measuring in medium-resolution mode and high-resolution mode. The applicability of the proposed method has also been validated by the analysis of reference material (NIST SRM 1643e). These results showed that the detection limit of this method is in the range of 0.002–0.34 μg/L with good precision (RSD < 3 %).     

Time-resolved fluorescent immunochromatographic assay-based on three antibody labels for the simultaneous detection of aflatoxin B1 and zearalenone in Chinese herbal medicines

ABSTRACT

A time-resolved fluorescent immunochromatographic assay (TRFICA) was successfully developed for the sensitive, simultaneous, and quantitative detection of aflatoxin B₁ (AFB1) and zearalenone (ZEN) in Chinese herbal medicines. Eu-nanospheres (EuNPs) with unique optical properties increased the stability and sensitivity of the immunochromatographic assay. To obtain stable quantitative results, we applied a three-label system in which monoclonal antibodies for AFB1 and ZEN were conjugated to the EuNPs as detection probes on the test line (T line), and EuNP-labelled chicken IgY conjugates acted as the reference on the control line (C line). The fluorescence intensities of the T and C lines were recorded, and the T/C ratio was employed as the quantitative signal for the elimination of strip variation and matrix effects. The parameters that affected the TRFICA were optimised. Under optimal conditions, the established TRFICA gave good linear ranges from 0.60 μg/kg to 3.92 μg/kg for AFB1 and from 0.40 μg/kg to 1.28 μg/kg for ZEN. The limits of detection for AFB1 and ZEN were as low as 0.60 and 0.40 μg/kg, respectively, in Chinese herbal medicines Semen coicis, Rhizoma dioscoreae, and Platycodon grandiflorus, respectively. The average recoveries of the spiked samples were 73%–95% for AFB1 and 75.83%–90% for ZEN, both with a relative standard deviation of < 9.08%. The results of 15 actual samples detected by the developed TRFICA showed a satisfactory correlation with those of ultra-performance liquid chromatography tandem mass spectrometry. Therefore, the TRFICA is a simple, rapid, and sensitive approach to quantitatively detect mycotoxins in Chinese herbal medicines.     

Flow-Based System for the Determination of Titratable Acidity in Wines

A flow injection analysis system with a spectrophotometric detection was arranged in order to develop a simple and fast methodology for the quantification of titratable acidity in different types of wines. In the proposed system, a precise volume of sample is injected in the carrier stream, composed by a mixture of OH^? solution with the pH indicator, bromothymol blue (BTB). Consequently, a change on the colour of the carrier solution is achieved and quantified by spectrophotometry. Therefore, it was possible to establish a linear range up to 0.16 g/L expressed as tartaric acid, with a limit of detection and quantification of 0.01 and 0.05 g/L, respectively. The proposed work has a low sample and reagents consumption, only 96 μg of BTB, 336 mmol de OH^? and 50 μL of sample were needed per assay. At the same time, a high determination rate was achieved, 75 determinations per hour. The developed methodology was applied on the quantification of total acidity in red and white table wine and port wine samples.     

Potential health hazards due to the occurrence of the mycotoxin tenuazonic acid in infant food

The mycotoxin tenuazonic acid (TA) was analyzed in different infant foods and beverages including tea infusions (fruit, herbal and fennel tea), puree infant food in jars (complementary food and side dishes) and infant cereals (for preparation of meals after addition of water or milk) by means of a stable isotope dilution assay (SIDA). The median content of TA in infant tea infusions (n = 12) was 2 μg/L, but values up to 20 μg/L were found in fennel tea infusions. In puree infant food in jars (n = 12), the median content of TA was 7 μg/kg, but higher values were detected in products containing tomato (25 μg/kg), banana and cherry (80 μg/kg) and sorghum (20 μg/kg). Infant cereals on the basis of wheat and/or oats, rice, spelt and barley (n = 4) did not contain TA in values higher than 30 μg/kg, but if sorghum was the major ingredient (n = 12), the mean content of TA was 550 μg/kg and the maximum level was 1,200 μg/kg. The European Food Safety Authority (EFSA) evaluated the toxicological potential of TA by following the threshold of toxicological concern (TTC) approach yielding a TTC value of 1,500 ng TA/kg body weight per day. Although long-term studies are needed to enlarge the database on TA contamination of sorghum-based infant food, our preliminary study points out to a tendency that the TTC value may be exceeded by infants consuming predominantly sorghum-based food. Nevertheless, further toxicity data on TA are required with high priority to assess potential health hazards.     

Determination of chloramphenicol and zeranols in pig muscle by immunoaffinity column clean-up and LC-MS/MS analysis

An immunoaffinity column clean-up and LC-MS/MS method was successfully developed for simultaneous determination of chloramphenicol, zearalanone, α-zearalanol, β-zearalanol, zearalenone, α-zearalenol and β-zearalenol in pig muscle. The sample was extracted with diethyl ether after enzymatic digestion by β-glucuronidase/sulfatase. The extracted solution was evaporated to dryness and the residue was then dissolved in 1 ml of 50% acetonitrile solution. After filtration and dilution with phosphate buffer solution (PBS), the reconstituted solution was cleaned-up with an IAC-CZ immunoaffinity column and then analysed by HPLC-MS/MS. The established method were validated by linearity (r ≥ 0.9990), precision (RSD ≥ 2.9%), average recovery (74.5–105.0%) and limit of detection (0.04–0.10 μg kg^–1). The developed method is rapid, reliable, sensitive, accurate and has good applicability for real samples.     

Quantification of Piperazine in Chicken Muscle by Ultra-Performance Liquid Chromatography-Electrospray Ionization Tandem Mass Spectrometry

An ultra-performance liquid chromatography-electrospray ionization tandem triple quadrupole mass spectrometry (UPLC-ESI/MS/MS) method was developed for the detection of piperazine in chicken muscle. Following extraction and purification, the chicken muscle extract was injected into the UPLC system and analyzed. Piperazine detection was performed on a triple-quadrupole mass spectrometer with the ESI interface operating in positive mode. The most sensitive mass transition from the precursor ion to the product ion was 87.1 → 44.1 for piperazine. The coefficient (R ²) of piperazine was 0.9995 in the range of 1–200 μg/kg. The recovery and relative standard deviation (RSD) ranged from 102.93 to 111.46% and from 4.57 to 5.28% at 50.0, 100.0 and 200.0 μg/kg adding levels, respectively. Limits of detection (LODs) and limits of quantification (LOQs) were 0.4 and 1.0 μg/kg, respectively. This method was fully validated based on its specificity, sensitivity, linearity, precision, accuracy, matrix effect, and stability results. Compared to other researches, this new method not only omitted the derivative process, which simplify the pre-processing, but also proved a better sensitivity based on its low LOD and LOQ values.     

Determination of Deoxynivalenol and Nivalenol in Wheat by Ultra-Performance Liquid Chromatography/Photodiode-Array Detector and Immunoaffinity Column Cleanup

An ultra-performance liquid chromatography (UPLC®) method has been developed for the simultaneous determination of deoxynivalenol (DON) and nivalenol (NIV) in wheat. Ground sample was extracted with water and the filtered extract was cleaned up through an immunoaffinity column containing a monoclonal antibody specific for DON and NIV. Toxins were separated and quantified by UPLC® with photodiode-array detector (λ?=?220 nm) in less than 3 min. Mean recoveries from blank wheat samples spiked with DON and NIV at levels of 100–2,000 μg/kg (each toxin) ranged from 85 to 95 % for DON and from 81 to 88 % for NIV, with relative standard deviations less than 7 %. Similar recoveries were observed from spiked samples when methanol/water (80:20, v/v) was used as extraction solvent. However, by using a wheat sample naturally contaminated with DON and NIV, the one-way analysis of variance (Student–Newman–Keuls test) between different extraction solvents and modes showed that water extraction provided a significant increase (P?<?0.001) in toxin concentrations (mean values of six replicate analyses) with respect to methanol/water (80:20, v/v). No significant difference was observed between shaking (60 min) and blending (3 min). The limit of detection (LOD) of the method was 30 μg/kg for DON and 20 μg/kg for NIV (signal-to-noise ratio 3:1). The immunoaffinity columns showed saturation of DON/NIV binding sites at levels higher than 2,000 ng in blank wheat extracts spiked with the corresponding amount of mycotoxin, as single mycotoxin or sum of DON and NIV. The range of applicability of the method was from LOD to 4,000 μg/kg, as single mycotoxin or sum of DON and NIV in wheat. The analyses of 20 naturally contaminated wheat samples showed DON contamination in all analyzed samples at level ranging from 30 to 2,700 μg/kg. NIV was detected in two samples at negligible toxin levels (up to 46 μg/kg). This is the first UPLC® method using immunoaffinity column cleanup for the simultaneous and sensitive determination of DON and NIV in wheat.     

Determination of Eugenol in Aquatic Products by Dispersive Solid-Phase Extraction and Ultra-High-Performance Liquid Chromatography-Tandem Mass Spectrometry

A novel procedure, dispersive solid-phase extraction coupled with ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS), was developed for the determination of eugenol in aquatic products (shrimp, crab, and carp). Aquatic products were extracted with acetonitrile and primarily purified by dispersive solid-phase extraction with graphitized carbon black as absorbent. The pretreated acetonitrile extract was detected by UHPLC-MS/MS. UHPLC was carried out on Dikma Endeavorsil C₁₈ (30 mm × 2.1 mm, 1.8 μm) column eluted by methanol and water (80:20 v/v) at a rate of 0.30 mL min^?1. Tandem mass spectrometry was performed by electrospray ionization in negative ion mode to identify and quantify eugenol during multiple reaction monitoring. Under optimized analytical conditions, the matrix-matched spiked calibration sample demonstrates good linearity between 5.0 and 500.0 μg kg^?1 with a linear regression coefficient of 0.9996. The average recovery of eugenol from aquatic products is 95.3–103.4% at spiked levels between 5 and 50 μg kg^?1 with a relative standard deviation (n = 6) less than 5.4%. The limits of detection and quantification for eugenol were calculated to be 1.47 and 4.91 μg kg^?1, respectively. In comparison with those reported, the proposed method has advantages in low detection limit, high recovery, and short analysis time, meeting the requirements for the determination of trace eugenol residue in aquatic products.     

Natural occurrence of fumonisins B1 and B2 in corn in four provinces of China

Fumonisin B₁ (FB₁) and fumonisin B₂ (FB₂) are the most abundant fumonisins (FBs) occurring worldwide in maize, infected mainly by Fusarium verticillioides and F. proliferatum. A total of 307 corn kernel samples were collected from 45 districts of Gansu, Shandong, Ningxia and the Inner Mongolia provinces of the north and northwest China. The samples were analysed for FB₁ and FB₂ by high-performance liquid chromatography. The FBs (FB₁+ FB₂) incidence rate in samples from Gansu, Shandong, Ningxia and Inner Mongolia were 31.5%, 81.1%, 46.2% and 53.6%, respectively. Average FBs concentration was 703 μg/kg and the concentrations ranged from ≤11 to 13,110 μg kg^?1. Results were compared with the European Commission (EC) regulation for FB₁+ FB₂ in unprocessed maize for human consumption of 4 mg kg^?1. Contamination in 17 samples was higher than these levels. More than 80% of the samples from Liaocheng county, which is located in the Shandong province, were contaminated with FBs, with a mean total FB concentration of 2496 μg/kg. The result was significantly different from that of the Inner Mongolia (1399 μg/kg), Ningxia (373 μg/kg) and Gansu (175 μg/kg). Average exposure to FBs (0.12 μg/kg body weight/day) is within the provisional maximum tolerable daily intake of 2.0 mg/kg of body weight set by the Joint Food and Agriculture Organization and World Health Organization Expert Committee on Food Additives.     

Determination of Antibiotic Residues in Honey by High-Performance Liquid Chromatography with Electronspray Ionization Tandem Mass Spectrometry

The aim of the present study was to develop a rapid and simple method for the detection and quantification of antibiotic and antibacterial residues in honey using liquid chromatography with electronspray ionization tandem mass spectrometry. Two different extraction methods were used. The first method uses water and 1% formic acid in acetonitrile for the determination of sulfonamides while the second uses phosphate buffer, 10% trichloroacetic acid, and acetonitrile as the extracting solvent for the determination of tetracyclines, amphenicols, fluoroquinolones, penicillin g, trimethoprim, and tiamulin. The multi-residue method was validated in a thyme honey matrix. Thirty-six different antibiotics and residues from four different families (sulfonamides, tetracyclines, amphenicols, fluoroquinolones) and some individual antibiotics (penicillin g, trimethoprim, and tiamulin) were tested in 20 honey samples originating from Cyprus and Greece. The decision limits (CCα) were from 0.1 to 9.2 μg kg^?1; the detection capabilities (CCβ) were from 0.3 to 27.6 μg kg^?1 while recoveries were from to be between 65.0 and 116.1%. The method was successfully applied to commercial samples from different types of honey from Greece and Cyprus. Among them, oxolonic acid, sulfathiazole, and sulfadimethoxine were found in three honey samples. Finally, proficiency testing was applied to the proposed method while analysis of certified samples showed good method performance characteristics.     

Ochratoxin A in dried vine fruits from Chinese markets

A total of 56 dried vine fruits, including 31 sultanas and 25 currants, were selected from Chinese markets in 2012. All samples were analysed for Ochratoxin A (OTA) using solid-phase extraction and high-performance liquid chromatography (HPLC) with fluorescence detection. It turned out that 58.9% of the samples were positive and the OTA amount ranged from <0.07 to 12.83 μg/kg, with a mean level of 0.99 μg/kg. Only one sample exceeded the European Union (EU) maximum level of 10 μg/kg. Meanwhile, it was shown that OTA contamination increased among north-western, northern and southern China, which showed OTA means of 0.08, 0.99 and 2.01 μg/kg, respectively. Moreover, in samples of products sold in sealed plastic bags, i.e. consumer-size packages (n = 19, mean = 0.30 μg/kg) less OTA was detected when compared with sampled bulk packages (n = 37, mean = 1.67 μg/kg). In addition, sultanas (mean = 0.92 μg/kg) had less OTA contamination than currants (mean = 1.22 μg/kg).