Rapid analysis of aflatoxins in raw peanuts,corn, buckwheat and red pepper by a new mini-column cleanup and HPLC using post-column photochemical derivatization system

A rapid and clean method for the analysis of aflatoxins (AFs) was developed by using a new column and post-column photochemical derivatization HPLC with fluorescence detection. The new cleanup column consisted of magnesia and basic alumina poured on the top of a commercial multi-functional mini-column. It was extremely effective for the cleanup of AFs from raw peanut, corn, buckwheat and red pepper. Fluorescent substances, which interfered with the analysis of AFs from corn, were completely absorbed at the top of the magnesia layer. Recoveries of AFs (B1, B2, G1, G2) added to raw peanuts, corn, buckwheat and red pepper were over 80% at two levels of fortification (higher level: 10, 3, 10, 3 ng/g, respectively, lower level: 1.0, 0.3, 1.0, 0.3 ng/g, respectively). Coefficients of variation were smaller than 12%, except the lower fortified level for red pepper. Limits of detection for AFs in raw peanuts, corn and buckwheat were 0.3 ng/g for B1 and G1, and 0.1 ng/g for B2 and G2. Those in red pepper were 0.5 ng/g for B1, B2, G1 and G2.     

Occurrence of aflatoxins in milk thistle herbal supplements

Milk thistle (MT) dietary supplements are widely consumed due to their possible liver-health-promoting properties. As botanicals they can be contaminated with a variety of fungi and their secondary metabolites, mycotoxins. The aflatoxigenic fungus Aspergillus flavus has been previously isolated from these commodities. Currently, there is no published method for determining aflatoxins (AFs) in MT. Therefore, a liquid chromatography (LC) method validated for aflatoxin analysis in botanicals was evaluated and applied to MT. The method consisted of acetonitrile/water extraction, immunoaffinity column clean-up, LC separation, post-column photochemical reaction derivatisation and fluorescence detection. The average recoveries for AFs added to MT seeds, herb, oil-based liquid extract and alcohol-based liquid extract were 76% or higher. The mean relative standard deviation was <10%. The limit of detection (LOD) was 0.01 μg kg(-1) and the limit of quantification (LOQ) was 0.03 μg kg(-1). The method was used to conduct a small survey. A total of 83 MT samples from the US market were analysed. AFs were detected in 19% of the samples with levels ranging from 0.04 to 2.0 μg kg(-1). Additionally, an aflatoxigenic A. flavus strain from ATTC and an A. parasiticus strain isolated from MT herb powder were found to produce high amounts of aflatoxins (11,200 and 49,100 μg kg(-1), respectively) when cultured in MT seed powder. This is the first study reporting on aflatoxin contamination of MT botanical supplements and identifying methodology for AF analysis of these commodities.     

Aflatoxin in household maize for human consumption in Kenya,East Africa

ABSTRACT

The objective of this study is to determine the occurrence and level of aflatoxins (AFs) contamination in freshly harvested maize for human consumption in rural Kenya. Maize kernels and freshly milled maize flour (n = 338) were collected from households in Siaya and Makueni counties. While both counties are representatives of different environmental and climate conditions, Makueni County is the area with reported outbreaks of aflatoxicosis. Samples were analysed for AFB₁, AFB₂, AFG₁, and AFG₂ using Ultra High-Pressure Liquid Chromatography with Fluorescence detection. AFs were detected in 100% of the samples with the range of 2.14–411 µg/kg. The geometric mean of total AFs in all samples from Makueni County is 62.5 μg/kg with 95% CI: 53.7, 71.4 while in Siaya County is 52.8 μg/kg with 95% CI: 44.0, 61.7. This study showed that AFs contamination is prevalent in maize-based foods in the region.     

Validation of the procedure for the simultaneous determination of aflatoxins ochratoxin A and zearalenone in cereals using HPLC-FLD

Method validation for quantitative analysis of aflatoxins (AFs), ochratoxin A (OTA) and zearalenone (ZEA) in cereals using HPLC with fluorescence detector (FLD) is described. Mycotoxins were extracted with methanol : water (80 : 20) and purified with a multifunctional AOZ immunoaffinity column before HPLC analysis. The validation of the analytical method was performed to establish the following parameters: specificity, selectivity, linearity, limits of detection (LOD) and quantification (LOQ), accuracy, precision (within- and between-day variability), stability, robustness, measurement of performance, and measurement of uncertainty. Calibration curves were linear (r > 0.999) over the concentration range, from the LOQ to 26, 40 and 400 ng/g for AFs, OTA and ZEA, respectively. LOD and LOQ were 0.0125 and 0.05 ng/g for aflatoxin B1 (AFB1) and G1 (AFG1), 0.0037 and 0.015 ng/g for aflatoxin B2 (AFB2) and G2 (AFG2), as well as 0.05 and 0.2 ng/g for OTA and 0.5 and 2 ng/g for ZEA, respectively. The mean recovery values were 77-104% for different concentrations of AFs, OTA and ZEA in spiked cereal samples. Both intra- and inter-day accuracy and precision were within acceptable limits. This method was successfully applied for the simultaneous determination of mycotoxins for 60 cereal samples collected from Malaysian markets. Fifty per cent of the cereal samples were contaminated with at least one of these mycotoxins, at a level greater than the LOD. Only one wheat sample and two rice samples were contaminated with levels greater than the European Union regulatory limits for AFs and OTA (4 and 5 ng/g). The means and ranges of mycotoxins obtained for the cereal samples were 0.4 ng/g and 0.01-5.9 ng/g for total AFs; 0.18 ng/g and 0.03-5.3 ng/g for OTA; and 2.8 ng/g and 2.4-73.1 ng/g for ZEA, respectively. The results indicate that the method is suitable for the simultaneous determination of AFs, OTA and ZEA in cereals and is suitable for routine analysis.     

In-house validation of PremiTest, a microbiological screening test with solvent extraction, for the detection of antimicrobial residues in poultry muscles

PremiTest, a microbial inhibition test for the screening of antimicrobial residues, was validated according to the criteria established by Decision 2002/657/EC. Sensitivity, detection capability (CCβ), specificity, selectivity, robustness and applicability were evaluated. The methodology involves the technique of solvent extraction, which increases the detection capability of the test for a wider range of antibiotics. The following CCβ values in poultry muscle were found: penicillin G ≤ 12.5 μg kg(-1), total sulfonamides ≤ 75 μg kg(-1), erythromycin 75 μg kg(-1) and lincomycin 50 μg kg(-1). The detection capability of chlortetracycline was equal to its maximum residue limit (100 μg kg(-1)) and the method did not detect gentamicin (1000 μg kg(-1)), for which no MRL is established in poultry muscle. Specificity evaluated in relation to different analytes and matrices did not detect any interferences in the tests results; whilst the robustness showed that the pH neutralisation point of the extract affects the analytical results and the kits' performance. Only the screening of tetracyclines requires the analysis of extracts without pH neutralisation. The results of the validation process showed that this method is acceptable for screening β-lactam, sulfonamide and macrolide antimicrobial groups in the National Residues and Contaminants Control Programme (PNCRC), and that for this it is fit for purpose.     

高效液相色谱法检测粮油中黄曲霉毒素方法验证

该文报道验证同时检测粮食、植物油中黄曲霉毒素B1、B2、G1和G2的免疫亲和柱净化-柱后光化学衍生-高效液相色谱方法.样品经甲醇-水(体积比为70∶30)提取,通过免疫亲和柱富集和净化,采用Cloversil C18色谱柱(4.6mm×150 mm,粒度5μm),以甲醇:水(50∶50)溶液为流动相,柱后光化学衍生,利...     

Development and validation of an indirect competitive enzyme-linked immunosorbent assay for monitoring quinoxaline-2-carboxylic acid in the edible tissues of animals

The feed drug additive carbadox is a suspected carcinogen and mutagen. To monitor effectively residues of carbadox in the edible tissues of food-producing animals, an indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) to detect quinoxaline-2-carboxylic acid, the marker residue of carbadox, was developed. Several haptens were synthesised and conjugated to the carrier protein. Nine female New Zealand white rabbits were immunised with the immunising conjugates to produce polyclonal antibodies according to the designed schemes of immunisation. The highly specific antibody that was very sensitive to N-butylquinoxaline-2-carboxamide with an IC(50) value of 7.75 μg l(-1) was selected for the development of an ic-ELISA. The standard curves based on the N-butylquinoxaline-2-carboxamide matrix calibration ranged from 0.2 to 51.2 μg l(-1). The decision limit and detection capability of the ic-ELISA were 0.60 and 0.83 μg kg(-1) for liver and 0.68 and 0.79 μg kg(-1) for muscle of swine, respectively. The recoveries were 57-108% with coefficients of variation of less than 20% when the quinoxaline-2-carboxylic acid was spiked into liver and muscle with the concentrations of 1.0-20.0 μg kg(-1). Excellent correlations between the results of the ic-ELISA and an HPLC method (r = 0.9956 - 0.9969) were observed for incurred tissues. These results suggest that the ic-ELISA is a sensitive, accurate and low-cost method that would be a useful tool for screening residues of carbadox in the edible tissues of food-producing animals.     

超高效液相色谱-串联质谱法同时测定动物源性食品中9种多肽类抗生素残留

建立了动物组织中9种多肽类抗生素残留的固相萃取-超高效液相色谱串联质谱（UPLC-MS/MS）检测方法。样品经甲醇-0.1 mol/L盐酸（7:3,v/v）混合溶剂提取,酸性氧化铝除杂、正己烷去除油脂,亲水-亲脂平衡（hydrophilic-lipophilic balance,HLB）固相萃取柱净化,以0.2%的甲酸水溶液和乙腈为流动相,经过C₈色谱柱（100A, 150 mm×2 mm, 3 μm）梯度洗脱分离,使用电喷雾正离子化和多反应监测模式检测。结果表明,万古霉素和去甲万古霉素、恩拉霉素A、恩拉霉素B、太古霉素在2～200 μg/L范围内,粘杆菌素A、粘杆菌素B、杆菌肽A在5～500 μg/L范围内,维吉尼霉素M1在0.1～20 μg/L范围内,各化合物定量离子的峰面积和样品质量浓度之间呈现良好的线性关系（R2>0.99）,方法的定量限（S/N=10）为1～20 μg/kg,检出限为0.3~6 μg/kg;以鸡肉、猪肉、猪肝、猪肾为基质,在加标水平为1～200 μg/kg时,各个化合物的平均加标回收率为74.2%～96.3%,相对标准偏差为4.3%～14.6%。该方法简便、灵敏、准确,可用于动物组织中多肽类抗生素残留的同时测定。     

Simultaneous determination of five penicillins in muscle,liver and kidney from slaughtered animals using liquid chromatography coupled with electrospray ionization tandem mass spectrometry

A simple and rapid method for the simultaneous determination of five penicillins (ampicillin, penicillin G, penicillin V, oxacillin and cloxacillin) in muscle, liver and kidney tissues using high-performance liquid chromatography-electrospray tandem mass spectrometry (LC-ESI-MS/MS) was developed. Mass spectral acquisition was done in the negative ion mode by applying selected reaction monitoring (SRM). The five penicillins were extracted with water, and the extracted solution was cleaned up on a C18 cartridge. Phenethicillin was added as an internal standard, and the extract was diluted with water for injection into the LC-ESI-MS/MS. The recoveries of the five penicillins were in the range of 77.3-99.8% from muscle, liver and kidney fortified at 10-250 ng/g. The detection limits for ampicillin were 6 ng/g in muscle and kidney and 15 ng/g in liver. For penicillin G and penicillin V, the detection limits were 2 ng/g in muscle and kidney and 5 ng/g in liver. For oxacillin and cloxacillin, the detection limits were 4 ng/g in muscle and kidney and 10 ng/g in liver. Twenty-three muscle, fourteen liver and twenty-two kidney samples from the markets were analyzed by this method. No penicillins were detected in any sample.     

Distribution and elimination of levamisole in eggs and tissues after oral administration to laying hens,determined by LC-MS/MS

Levamisole was administered to laying hens, and concentrations in eggs and tissues (thigh muscle, breast muscle, liver and kidney) were determined by a newly developed liquid chromatography tandem mass spectrometry method, which allowed trace level quantification of levamisole. The adopted analytical method showed good sensitivity, repeatability and percentage of recovery from spiked matrices. Maximum concentrations of levamisole were found on the first day after the administration (531.1 μg/kg in liver, 164.3 μg/kg in egg yolk, 130.7 μg/kg in kidney, 78.0 μg/kg in breast muscle, 70.7 μg/kg in thigh muscle and 64.0 μg/kg in egg white), after which there is a decline. The compound was rapidly eliminated from eggs, with a half-life of 1.3 days. Elimination appeared to be slower in thigh muscle (3.5 days), breast muscle (3.4 days) and liver (3.3 days). According to this experiment, the levamisole withdrawal periods calculated for eggs, liver, kidney, breast muscle and thigh muscle in laying hens were 14.1, 6.1, >4.0, 14.5 and 13.0 days, respectively. The longest time for levamisole residues to be completely released from tissues was seen in liver samples (37.4 days), followed by thigh muscle, breast muscle and kidney. Elimination from eggs was fastest (16.4 days for levamisole residues to drop below the method quantification limit).     

Aflatoxin (B1, B2, G1, and G2) Contamination in Rice of Mexico and Spain,from Local Sources or Imported

Rice is an important cereal but it is often contaminated with aflatoxins (AFs). The purpose of this study was to identify and quantify AF (B₁, B₂, G₁, and G₂) in 67 rice samples cultivated in Mexico and Spain, and from imported crops collected in 2008 and 2009. The methodology was validated, the rice samples were concentrated and purified with immunoaffinity columns and were quantified by high‐pressure liquid chromatography (HPLC). The average total AF (AFt) in the Spanish rice was 37.3 μg/kg, the range was from 1.6 to 1383 μg/kg, the most contaminated samples being from San Juan de Aznalfarache, Sevilla (AFt = 138.6 μg/kg), from Tortosa, Tarragona (AFt = 104.6 μg/kg), and Calasparra, Murcia (AFt = 103.9 μg/kg). The rice imported from France to Spain had AFt of 26.6 μg/kg and from Pakistan AFt of 18.4 μg/kg, showing less AF contamination than the local one. The rice which originated from Mexico contained (AFt = 16.9 μg/kg), and those imported from the United States (AFt = 14.4 μg/kg) and Uruguay (AFt = 15.6 μg/kg). The imported rice had better quality in terms of the presence of AFs.     

Validation of the procedure for the simultaneous determination of aflatoxins ochratoxin A and zearalenone in cereals using HPLC-FLD

Method validation for quantitative analysis of aflatoxins (AFs), ochratoxin A (OTA) and zearalenone (ZEA) in cereals using HPLC with fluorescence detector (FLD) is described. Mycotoxins were extracted with methanol?:?water (80?:?20) and purified with a multifunctional AOZ immunoaffinity column before HPLC analysis. The validation of the analytical method was performed to establish the following parameters: specificity, selectivity, linearity, limits of detection (LOD) and quantification (LOQ), accuracy, precision (within- and between-day variability), stability, robustness, measurement of performance, and measurement of uncertainty. Calibration curves were linear (r?>?0.999) over the concentration range, from the LOQ to 26, 40 and 400?ng/g for AFs, OTA and ZEA, respectively. LOD and LOQ were 0.0125 and 0.05?ng/g for aflatoxin B1 (AFB1) and G1 (AFG1), 0.0037 and 0.015?ng/g for aflatoxin B2 (AFB2) and G2 (AFG2), as well as 0.05 and 0.2?ng/g for OTA and 0.5 and 2?ng/g for ZEA, respectively. The mean recovery values were 77–104% for different concentrations of AFs, OTA and ZEA in spiked cereal samples. Both intra- and inter-day accuracy and precision were within acceptable limits. This method was successfully applied for the simultaneous determination of mycotoxins for 60 cereal samples collected from Malaysian markets. Fifty per cent of the cereal samples were contaminated with at least one of these mycotoxins, at a level greater than the LOD. Only one wheat sample and two rice samples were contaminated with levels greater than the European Union regulatory limits for AFs and OTA (4 and 5?ng/g). The means and ranges of mycotoxins obtained for the cereal samples were 0.4?ng/g and 0.01–5.9?ng/g for total AFs; 0.18?ng/g and 0.03–5.3?ng/g for OTA; and 2.8?ng/g and 2.4–73.1?ng/g for ZEA, respectively. The results indicate that the method is suitable for the simultaneous determination of AFs, OTA and ZEA in cereals and is suitable for routine analysis.     

磺胺甲噁唑和磺胺嘧啶在青石斑鱼组织中的分布及代谢规律

通过一次性投喂各含有200 mg/kg磺胺甲噁唑（sulfamethoxazole,SMZ）和磺胺嘧啶（sulfadiazine,SDZ）的饲料,研究两种药物在青石斑鱼中各组织分布与消除规律。采用超高效液相色谱-串联质谱检测青石斑鱼各组织中SMZ和SDZ的含量,并用内标法定量。结果表明,SMZ在青石斑鱼各组织中的最大含量：肝脏、背肌、血浆、肾脏和鳃依次为827.97μg/kg、776.70μg/kg、610.29μg/L、432.14μg/kg和345.18μg/kg。SDZ在青石斑鱼各组织中的最大含量：肝脏、背肌、鳃、血浆和肾脏依次为895.30μg/kg、660.55μg/kg、431.88μg/kg、419.56μg/L和310.67μg/kg。SMZ在青石斑鱼各组织中的半衰期：肾脏、鳃、背肌、血浆和肝脏半衰期依次为26.65、21.00、20.38、18.73h和16.90h。SDZ在青石斑鱼各组织中的半衰期：肾脏、血浆、鳃、背肌和肝脏依次为31.50、27.72、24.75、21.66h和18.24h。SMZ和SDZ在青石斑鱼肝脏中半衰期最短,代谢速度最快;在肾脏中半衰期最长,代谢速度最慢。在水温（25±2）℃条件下,SMZ和SDZ各200mg/kg的剂量同时单次投喂青石斑鱼,建议休药期不低于3d。SMZ和SDZ代谢规律研究为磺胺类药物在水产品中的合理使用提供了参考。     

石斑鱼中阿维菌素类药物多残留测定及食用安全风险评估

建立高效液相色谱-串联质谱同时定量检测石斑鱼血浆、肌肉组织、肝脏组织中阿维菌素、伊维菌素、甲氨基阿维菌素苯甲酸盐方法。样品经乙腈提取,碱性氧化铝固相萃取柱和LC-C18固相萃取柱串联净化,Thermo Hypersil Gold C18色谱柱分离,10 mmol/L乙酸铵-0.1%甲酸溶液和乙腈梯度洗脱,电喷雾正离子模式下以多反应监测方式检测,基质匹配法外标定量。分别以环境水体中阿维菌素上下限质量浓度(4、8 ng/mL)、伊维菌素上下限质量浓度(6、12 ng/mL)作为受试质量浓度开展生物富集、消除实验,并对石斑鱼的食用安全进行了风险评估。结果表明,阿维菌素和伊维菌素在2.5~200 ng/mL范围内,甲氨基阿维菌素苯甲酸盐在0.25~20 ng/mL范围内,线性回归系数均大于0.99。方法检出限分别为2.5、2.5、0.25 ng/mL(血浆),1、1、0.1μg/kg(肌肉组织),2.5、2.5、0.25μg/kg(肝脏组织),方法定量限分别为5、5、0.5 ng/mL(血浆),2、2、0.2μg/kg(肌肉组织),5、5、0.5μg/kg(肝脏组织)。3个添加量的平均回收率为74.6%~93.6%,日内相对标准偏差为2.3%~10.9%,日间相对标准偏差为9.2%~12.6%。阿维菌素、伊维菌素均属于非生物累积性物质,在石斑鱼体内代谢规律相同,均按一级动力学过程从体内消除。本研究条件下,环境水体中药物质量浓度是石斑鱼肌肉组织中药物残留质量浓度及消除时间的重要因素。为保证食用安全,环境水体中阿维菌素质量浓度达到4~8 ng/mL时,石斑鱼浸浴72 h后安全食用时间为22 d;环境水体中伊维菌素质量浓度达到6~12 ng/mL时,石斑鱼浸浴72 h后安全食用时间为39 d。     

Simultaneous determination of 15 aminoglycoside(s) residues in animal derived foods by automated solid-phase extraction and liquid chromatography-tandem mass spectrometry

An automated method has been developed for the simultaneous quantification of 15 aminoglycosides in muscle, liver (pigs, chicken and cattle), kidney (pigs and cattle), cow milk, and hen eggs by liquid chromatography tandem mass spectrometry. Homogenized samples were extracted by monopotassium phosphate buffer (including ethylene diamine tetraacetic acid), and cleaned up with auto solid-phase extraction by carboxylic acid cartridges. The analytes were separated by a specialized column for aminoglycosides, and eluted with trifluoroacetic acid and acetonitrile. The decision limits (CCα) of apramycin, gentamycin, tobramycin, paromomycin, hygromycin, neomycin, kanamycin, sisomicin, netilmicin, ribostamycin, kasugamycin, amikacin, streptomycin, dihydrostreptomycin and spectinomycin were ranged from 8.1 to 11.8 μg/kg and detection capabilities (CCβ) from 16.4 to 21.8 μg/kg. High correlation coefficients (r(2)>0.99) of calibration curves for the analytes were obtained within linear from 20 to 1000 μg/kg. Reasonable recoveries (71-108%) were demonstrated with excellent relative standard deviation (RSD). This method is simple pretreatment, rapid determination and high sensitivity, which can be used in the determination of multi-aminoglycosides in complex samples.     

QuEChERS-高效液相色谱-质谱联用法同时检测鸡胗和鸡肝中15种喹诺酮类和四环素类抗生素

为建立可以同时准确检测鸡胗和鸡肝中11 种喹诺酮类和4 种四环素类抗生素的分析方法,采用QuEChERS（quick, easy, cheap, effective, rugged, safe）法进行样品前处理,经过冰乙酸-乙腈-水溶液（1∶84∶15,V/V）提取,Discovery? DSC-18吸附剂净化,使用高效液相色谱-质谱联用仪进行检测,选用甲醇-0.1%甲酸体系作为流动相对目标物进行梯度洗脱,采用多反应监测模式进行检测。结果表明：15 种抗生素在质量浓度2～80 ng/mL范围内与其响应值存在良好的线性关系（R2≥0.993 3）,方法检出限为0.5～3.0 μg/kg,定量限为1.7～10.0 μg/kg,平均加标回收率为75.2%～104.4%,相对标准偏差为2.7%～8.7%;随机抽取100 份样品（其中鸡胗样品51 份,鸡肝样品49 份）用上述方法进行检测,15 种抗生素的总体检出率为21.38%,残留量为3.48～154.00 μg/kg。     

Multi-residue method for the confirmation of four avermectin residues in food products of animal origin by ultra-performance liquid chromatography-tandem mass spectrometry

A confirmatory method was developed for the rapid determination of abamectin, ivermectin, doramectin and eprinomectin residues in various food products of animal origin, such as pork muscle, pork liver, fish and milk. Samples were homogenized, extracted and de-proteinized by acetonitrile, cleaned via two-step cleaning procedure using Bond Elut C(18) SPE columns and then alumina-N cartridges. All the four avermectin residues in different animal-food products were simultaneously separated and determined by ultra-performance liquid chromatography-electrospray ionization tandem mass spectrometry (UPLC-ESI-MS/MS) within 3.5 min. Data acquisition under positive ESI-MS/MS was performed by applying multiple reaction monitoring (MRM) for both identification and quantification, and mass spectrometric conditions were optimized to increase selectivity and sensitivity. The matrix-matched calibration curves for different matrices, such as pork muscle, pork liver, fish and milk, were constructed and the interference effect of different sample matrices on the ionization was effectively eliminated. The UPLC-MS/MS method was validated with satisfactory linearity, recovery, precision and stability. Matrix-matched calibration curves of abamectin, ivermectin, doramectin and eprinomectin in four different matrices were linear (r(2)( )≥ 0.990, goodness-of-fit coefficients ≤12.8%) in the range 2.5-200 μg kg(-1). The limits of detection and quantification for the four avermectins were in the range 0.05-0.68 and 0.17-2.27 μg kg(-1), respectively. Recoveries were 62.4-104.5% with good intra- and inter-day precision. The method was rapid, sensitive and reliable, and can be applied to the quantitative analysis of avermectin residues in different animal-food products.     

高效液相色谱-串联质谱法同时测定花生制品中的黄曲霉毒素B1、B2、G1、G2

采用高效液相色谱-串联质谱建立了高效液相色谱-串联质谱法同时测定花生制品中4种黄曲霉毒素(B1、B2、G1、G2)的方法.结果表明,在ESI正离子模式下,高效液相色谱-串联质谱法的最低检出限为0.2μg/kg,定量限为0.6 μg/kg;标准工作液在0.5～50.0μg/kg的范围内线性良好,相关系数达到0.9990.     

Co-occurrence of aflatoxins B₁, B₂, G₁ and G₂, ochratoxin A, zearalenone, deoxynivalenol, and citreoviridin in rice in Brazil

A total of 230 samples of processed rice and its sub-products or derived products were analysed to establish the co-occurrence of several mycotoxins. Samples were analysed in the period 2007-2009 due to the outbreak of beriberi associated with the consumption of rice stored in inappropriate conditions in Brazil. According to data from the Ministry of Health, 323 cases of disease were registered in 2006, of which at least 47 cases resulted in death. The occurrence of total aflatoxin (AFT) (aflatoxin B(1)?+ B(2)?+ G(1)?+ G(2)), ochratoxin A (OTA), zearalenone (ZON), deoxynivalenol (DON), and citreoviridin (CTV) was 58.7%, 40.0%, 45.2%, 8.3% and 22.5%, respectively. From 166 rice samples analysed, 55% had levels <0.11 μg kg(-1) for AFT. For OTA and ZON, of 165 rice samples analysed, 28% and 29% were contaminated with levels from 0.20 to 0.24 μg kg(-1) and from 3.6 to 290.0 μg kg(-1), respectively. One sample (0.6%) was contaminated with 4872.0 μg kg(-1) of ZON. A total of 91% of rice samples (n = 165) did not contain detectable DON (<30.00 μg kg(-1)), although the highest level of contamination was found to be 244?μg?kg(-1). From the total of 65 samples analysed, 94% had no detectable CTV (<0.9?μg?kg(-1)), with a range from 0.9 to 31.1?μg?kg(-1) in 6% of the samples. The highest levels of contamination were found in rice sub-products or derived products from the husk and rice bran. Co-occurrence was observed for AFT and ZON in 17.0%, AFT and OTA in 24.2%, AFT and CTV in 6.2%, OTA and CTV in 4.6%, and ZON and CTV in 3.1%. These fractions were also the major contributors for the co-occurrence. The results found show the necessity of monitoring rice production.     

Rapid screening method for quinolone residues in livestock and fishery products using immobilised metal chelate affinity chromatographic clean-up and liquid chromatography-fluorescence detection

An efficient LC method was developed for screening the presence of quinolones (QLs)--comprising fluoroquinolones (FQs) and acidic quinolones (AQs)--residues in various livestock and fishery products. Targeted analytes were for nine FQs of marbofloxacin (MAR), ofloxacin (OFL), norfloxacin (NOR), ciprofloxacin (CIP), enrofloxacin (ENR), danofloxacin (DAN), orbifloxacin (ORB), difloxacin (DIF) and sarafloxacin (SAR), and three AQs of oxolinic acid (OXA), nalidixic acid (NAL) and flumequine (FMQ). Samples comprised ten different food products covering five matrices: muscle (cattle, swine and chicken), liver (chicken), raw fish (shrimp and salmon), egg (chicken), and processed food (ham, sausage and fish sausage). This method involved a simple extraction with (1:1) acetonitrile-methanol, a highly selective clean-up with an immobilised metal chelate affinity column charged with Fe(3+), a fast isocratic LC analysis using a short column (20 mm × 4.6 mm, 3 μm) with a mobile phase of (15:85:0.1) methanol/water/formic acid, and fluorescence detection (excitation/emission wavelengths of 295 nm/455 nm for FQs (495 nm for MAR), and 320 nm/365 nm for AQs). Among FQs, pairs of NOR/OFL, ORB/DIF and ENR/DAN were incompletely resolved. A confirmatory LC run with a Mg(2+) containing methanolic mobile phase was also proposed for the samples suspected of being positive. The optimised method gave satisfactory recoveries of 88.5% (56.1-108.6%) and 78.7% (44.1-99.5%) for intra- and inter-day assays with relative standard deviations of 7.2% (0.7-18.4%) and 6.8% (1.4-16.6%), respectively. Limits of quantitation ranged from 0.8 μg kg(-1) (DAN) to 6.5 μg kg(-1) (SAR). This method was successfully employed to analyse 113 real samples and two positive samples were found: fish sausage (CIP 990 μg kg(-1)) and shrimp (ENR 20 μg kg(-1)).