QuEChERS-超高效液相色谱法测定谷物及油籽中氰氟草酯和氰氟草酸残留量

目的:建立了一种能同时检测谷物和油籽中氰氟草酯和氰氟草酸残留量的QuEChERS-超高效液相色谱法。方法:称取样品2.0 g和5.0 g,用0.1%甲酸水-乙腈（1:1,V/V）提取,经N-丙基乙二胺（PSA）、C₁₈、氯化钠、无水硫酸镁等净化后,过0.22 μm滤膜,以0.1% 磷酸水溶液-甲醇-乙腈为流动相进行梯度洗脱,使用ACQUITY UPLC BEH C₁₈（50 mm× 2.1 mm, 1.7 μm）色谱柱分离,UPLC分析检测,外标法定量。结果:在0.002~5 μg/mL范围内,氰氟草酯和氰氟草酸的质量浓度与峰面积呈良好的线性关系,谷物和油籽中的定量限浓度分别为0.01 mg/kg和0.02 mg/kg。谷物中氰氟草酯和氰氟草酸加标回收率分别为89.23%~101.12%和87.98%~100.02%,油籽中分别为85.12%~92.34%和82.63%~89.55%,相对标准偏差均为1.1%~3.3%。结论:该方法前处理过程简单,检测过程准确、高效,灵敏度和准确度达到了农残检测的要求,适用于谷物和油籽中氰氟草酯和氰氟草酸的残留检测。     

QuEChERS-超高效液相色谱法检测果蔬中氰氟草酯和氰氟草酸残留

利用优化后的QuEChERS前处理条件结合超高效液相色谱，建立果蔬中氰氟草酯和氰氟草酸残留的检测方法。样品采用V(乙腈)∶V(甲酸)=99∶1超声提取，随后用NaCl、无水MgSO₄盐析分层，经乙二胺-N-丙基硅烷化硅胶(propylethylene diamine, PSA)、石墨化炭黑(graphitized carbon black, GCB)和无水MgSO₄吸附剂组合净化，采用C18色谱柱分离，以甲醇-水-乙腈-0.1%磷酸为流动相，梯度洗脱，在248 nm下检测，以基质匹配标准溶液法定量。结果表明，氰氟草酯和氰氟草酸在0.01～10μg/mL范围内线性关系良好，相关系数均大于0.998 9。氰氟草酯和氰氟草酸在7种果蔬基质中的平均加标回收率为73.1%～105.6%,相对标准偏差为1.5%～7.8%。方法检出限为1.0～2.5μg/kg,定量限为10～20μg/kg。该方法灵敏度高、重现性好，适用于果蔬中氰氟草酯和氰氟草酸残留的快速筛查和定量分析。     

高效氯氟氰菊酯在香蕉中的残留消解及膳食风险评估

为了探究高效氯氟氰菊酯在香蕉中的残留消解行为和膳食摄入风险,选择海南儋州（巴西蕉）、广西南宁（威廉斯香蕉）、云南玉溪（巴西蕉）、广东佛山（过山香）四个试验地进行田间试验,采用气相色谱对高效氯氟氰菊酯在香蕉全果及果肉中的残留消解结果进行测定,并对其长期膳食暴露风险进行评估。结果表明:高效氯氟氰菊酯标准曲线线性方程为y=155711x?387.55,R2=0.9997,在0.01~1 mg/kg的添加水平下,平均回收率为79%~110%,相对标准差（RSD）为2.2%~9.5%;在香蕉中的最低检出浓度为0.01 mg/kg;高效氯氟氰菊酯在香蕉中的消解动态符合一级动力学方程,半衰期为22.1 d,消解动态方程为C=0.12878e?0.03136t;评估结果显示高效氯氟氰菊酯的膳食风险概率为76.84%,表明香蕉中残留的高效氯氟氰菊酯长期摄入膳食风险可接受。     

慈溪市葡萄农药残留膳食摄入风险评估

目的开展葡萄农药残留膳食摄入风险评估工作,为葡萄食用、农药残留监管和农药最大残留限量提供科学依据。方法在2008~2013年对慈溪市生产的169批次葡萄样品进行了23种农药残留定量检测分析,分别用%ADI和%ARf D进行农药残留慢性膳食摄入风险评估和急性膳食摄入风险评估,用ADI值、大份餐和体重等参数计算最大残留限量估计值(eMRL)。结果近6年葡萄农药检出率为24.85%,超标率为0.59%。检出的7种农药慢性膳食摄入风险(%ADI)为0.010%~1.34%,平均值为0.23%;急性膳食摄入风险(%ARf D)为0.98~28.30%,平均值为8.90%。葡萄农药残留慢性膳食摄入风险和急性膳食摄入风险均很低。结论检出的7种农药最大残留限量(MRLs)均过严,建议将敌敌畏、乙酰甲胺磷、百菌清、氯氟氰菊酯、氯氰菊酯、氰戊菊酯、腐霉利等7种农药的最大残留限量分别定为0.5、3.5、2.5、2.5、2.5、2.5、11 mg/kg。     

吡唑醚菌酯在枇杷中的残留行为及膳食风险评估

目的 探明吡唑醚菌酯在枇杷中的残留特性,评价其使用安全性。方法 样品经乙腈提取, N-丙基乙二胺分散吸附剂净化, 0.1%甲酸水溶液和乙腈作为流动相进行梯度洗脱, 超高效液相色谱-串联质谱多反应监测模式检测,采用基质匹配标准溶液外标法定量。采用超高效液相色谱-串联质谱检测枇杷中的吡唑醚菌酯的残留量,进行膳食风险评估。 结果 在0.01、0.10、1.00和3.00 mg/kg添加水平下,吡唑醚菌酯在枇杷样品中的平均添加回收率在92%~96%之间,相对标准偏差范围为3.3%~5.4%,定量限为0.01 mg/kg。吡唑醚菌酯在枇杷中的消解半衰期为9.5~12.8 d。风险评估结果表明,我国普通人群摄入吡唑醚菌酯的风险概率为60.3%。不同年龄段人群膳食摄入评估结果表明显示,随采收间隔期的延长及年龄增加,风险概率逐渐降低。结论 30%吡唑醚菌酯悬浮剂,按推荐剂量(有效成分 250 mg/kg)施药2次,施药间隔7 d,推荐安全间隔期为14 d。在此条件下,其对我国一般人群产生的风险在可接受范围内。     

二甲四氯异辛酯及其代谢物二甲四氯在玉米中的残留量及风险评估

目的 明确鲜食玉米和成熟期籽粒中2甲4氯异辛酯及其代谢物2甲4氯残的残留水平,评价其膳食摄入风险。方法 以改进的QuEChERS前处理方法同时提取玉米中2甲4氯异辛酯和2甲4氯残留物,分别用用气相色谱-串联质谱法和液相色谱-串联质谱法检测2甲4氯异辛酯和2甲4氯的残留量。结果 2甲4氯异辛酯和2甲4氯仪器最小检出量(LOD)分别为2×10_^-12 g和5×10_^-12 g;在鲜食玉米、成熟期籽粒的最小检出浓度( LOQ)均为0.005 mg/kg,整体回收率为71%~114%,相对标准偏差(RSD)为1.2%~7.2 %。结论 该方法的准确度和精密度良好,2甲4氯异辛酯在鲜食玉米中残留量为<0.005~0.032 mg/kg,成熟期籽粒中残留量为<0.005~0.022 mg/kg,均<0.05 mg/kg;代谢物2甲4氯在鲜食玉米、成熟期籽粒中的最终残留量均<0.005 mg/kg;玉米中2甲4氯异辛酯及其代谢物2甲4氯残的膳食风险较低。     

吡唑醚菌酯在小麦上的残留分析及安全性评价研究

目的建立超高效液相色谱-串联质谱法(ultra performance liquid chromatography/tandem mass spectrometry,UPLC-MS/MS)测定小麦中吡唑醚菌酯的含量,研究其在小麦籽粒和秸秆中的残留状况及消解规律,评估吡唑醚菌酯的膳食风险。方法实验样品经乙腈提取、净化后,经Waters Acquity UPLC BEH C_(18)柱(50 mm×2.1 mm,1.7μm)分离,以0.1%甲酸水-甲醇为流动相进行梯度洗脱;流速为0.3 mL/min,多反应监测模式监测。结果吡唑醚菌酯在0.0005-0.20 mg/mL的范围内线性关系良好,相关系数大于0.999,小麦籽粒、小麦秸秆不同添加水平下的平均回收率范围为66%～97%、88%～98%,相对标准偏差分别为1.9%～5.5%、1.2%～12.4%,定量限为0.01 mg/kg。吡唑醚菌酯在小麦籽粒中的残留消解符合一级动力学方程,其消解半衰期为2.74～5.82 d;用药后小麦籽粒中吡唑醚菌酯的最终残留未检出～0.10 mg/kg;膳食风险评估表明,末次施药21 d后吡唑醚菌酯的国家估算每日摄入量是1.0874 mg,风险概率为57.53%。结论吡唑醚菌酯在小麦中的消解速度较快,虽不能在小麦中完全降解,但通过膳食评估发现长期膳食摄入对人体健康不会产生不可接受的风险。     

33%氯氟·吡虫啉悬浮剂在柑橘中的残留动态与膳食风险评估

采用QuEChERS前处理技术结合超高效液相色谱—串联质谱仪(UPLC-MS/MS)同时检测柑橘中33%氯氟·吡虫啉悬浮剂2种有效成分(高效氯氟氰菊酯和吡虫啉)的残留,并对该复配农药在柑橘田残试验中的残留消解动态规律进行了研究。试验结果表明:2种有效成分在柑橘全果上的消解规律均符合一级动力学关系,拟合优度r=0.956 0～0.992 3,高效氯氟氰菊酯、吡虫啉半衰期分别为8.2～9.8,5.5～7.6d,最终降解率均在92%以上;最终残留量表明,最终残留量与施药剂量、施药次数及采收间隔期呈正相关;2种有效成分的残留主要分布于果皮,其次为全果和果肉;距末次施药28d后,柑橘全果中吡虫啉和高效氯氟氰菊酯的残留量均低于国家标准(GB 2763—2016)中规定的MRL值,膳食风险评估结果表明,其残留对6类典型人群的风险均在人体可接受范围内。因此建议33%氯氟·吡虫啉悬浮剂以1 000倍稀释液(330mg/kg)施药,1个柑橘生产周期最多施药2次,施药间隔期10d,采收安全间隔期为28d对柑橘种植进行技术指导。     

新疆红枣农药残留风险评估与排序

为明确残留农药对新疆红枣质量安全的危害水平及其排序,本文以新疆10县市产出的124份红枣样品为研究对象,并对37种农药残留进行了测定,在此基础上,通过急性、慢性膳食摄入风险分析,探讨了残留农药对红枣质量安全的危害水平;并采用风险矩阵,对残留农药进行了风险排序。结果显示,样品中残留11种农药;残留农药的% ADI(慢性膳食摄入风险)值远小于100%;10种农药的% ARfD值(急性膳食摄入风险)也远低于100%;较其他残留农药,哒螨灵、毒死蜱、苯醚甲环唑、氯氟氰菊酯、氯氰菊酯、甲氰菊酯6种残留农药风险值相对较高,均大于12.05。结论:新疆红枣残留农药的膳食风险较低,哒螨灵、毒死蜱、苯醚甲环唑、氯氟氰菊酯、氯氰菊酯、甲氰菊酯为需重点关注的农药。     

喹啉铜在枇杷上的消解、储藏稳定性及风险评估

目的评估喹啉铜在枇杷中的残留消解、储藏稳定性和慢性膳食风险。方法实验样品用草酸溶液提取,亲水亲脂平衡(hydrophilic-lipophilic balance, HLB)固相萃取柱净化,超高效液相色谱检测,外标法定量,评估储藏稳定性和慢性膳食风险。结果喹啉铜在枇杷上的消解速率符合一级动力学方程,半衰期为3.4～4.6 d。枇杷样品在–18℃储藏150 d,喹啉酮的降解率小于30%。膳食风险评估结果表明,各年龄段人群喹啉铜的估算每日摄入量为0.0891～0.6945μg/kg bw/d,膳食摄入风险为0.45%～3.47%。结论喹啉铜在枇杷中消解较迅速;喹啉铜在枇杷样品中储藏稳定期至少为150d;对不同年龄阶段人群的长期慢性膳食暴露风险极低,均在可接受范围之内。     

液相色谱-串联质谱法检测蜂蜜中氟苯尼考及其代谢物残留量

目的 建立液相色谱-串联质谱法检测蜂蜜中氟苯尼考及其代谢物残留量的分析方法。方法 样品经氨化乙酸乙酯提取,通过DPC-2固相萃取柱净化,采用Poroshell 120 EC-C18柱分离,以10 mmol/L乙酸铵溶液-乙腈为流动相进行梯度洗脱,电喷雾正/负离子切换,多反应监测模式检测,同位素内标法定量。结果 氟苯尼考在0.2～30 μg/L时具有良好的线性关系,相关系数大于0.999,检出限为0.05 μg/kg,回收率为85.5%~116.3%,相对标准偏差小于10%。氟苯尼考胺在1～30 μg/L时具有良好的线性关系,相关系数大于0.999,检出限为0.3 μg/kg,回收率为85.6%~113.5%,相对标准偏差小于10%。结论 该方法快速、准确、灵敏, 适用于蜂蜜中氟苯尼考及其代谢物残留量的测定。     

氢核磁共振结合支持向量机鉴别蜂蜜植物源

目的建立基于氢核磁共振(1H nuclear magnetic resonance,1H NMR)结合支持向量机分类模型鉴别蜂蜜植物源的方法。方法采集荆条蜜、油菜蜜、洋槐蜜、葵花蜜4种不同植物源的蜂蜜共计122例样品的谱图信息,分全谱(δ0.10~δ9.50)、脂肪区(δ0.10~δ3.00)、糖类化合物区(δ3.00~δ6.00)、芳香区(δ6.00~δ9.50)4个不同积分区间建立分类模型,结合主成分权值系数筛选特征变量,进一步优化判别模型。结果基于主成分权值系数筛选变量范围δ3.40~δ3.90和δ4.60~δ4.70内共计267个积分变量,以该区域积分变量为输入变量建立的支持向量机分类模型,对训练集的判别正确率为97.53%,对测试集的判别正确率为100%。结论通过主成分权值系数能有效筛选特征变量,减少输入变量的同时提高模型稳健性与准确性,基于氢核磁共振结合支持向量机分类模型能有效鉴别不同植物源蜂蜜。     

四极杆碰撞反应池-电感耦合等离子体质谱法测定粉条中的铝

目的 建立四级杆碰撞反应池-电感耦合等离子体质谱法(ICP-MS)测定粉条中铝元素的分析检测方法。方法 样品经微波消解后使用电感耦合等离子体质谱仪进行检测,使用内标元素45Sc消除基体干扰和信号漂移,碰撞反应池(KED模式)消除质谱干扰。结果 铝元素校正曲线相关系数为0.999783 ,方法检出限为0.045 mg/kg,相对标准偏差为 0.79 %,加标回收率86.4 %～97.8 %,粉丝粉条中铝成分分析标准物质检测结果在认定值范围内。结论 该方法灵敏度高、准确性高、精密度好,是一种快速、准确的粉条中铝元素含量的检测方法。     

Aflatoxins in sunflower seeds and unrefined sunflower oils from Singida,Tanzania

A total of 61 samples comprising sunflower seeds (40) and unrefined sunflower oils (21) samples collected randomly from Singida, Tanzania were analysed by Reverse Phase-high performance liquid chromatography (RP-HPLC). 15% (6/40) of the seed samples were contaminated with aflatoxin B₁ ranging from limit of detection (LOD) to 218 ng g^?1 with three of them exceeding the European Commission/European Union (EC/EU) and Tanzania Bureau of Standards (TBS)/Tanzania Food and Drug Authority (TFDA) maximum limits of 2 ng g^?1 for AFB₁ in oilseeds. The levels of total aflatoxins (AFT) in seeds ranged from LOD to 243 ng g^?1. Other aflatoxins, except AFG₂, were also detected. For the unrefined sunflower oils, the levels of AFB₁ ranged from LOD to 2.56 ng mL^?1. About 80.9% (17/21) of the analysed oil samples contained AFB₁ of which 17.65% (3/17) exceeded the EC/EU and TBS/TFDA maximum limits of 2 ng mL^?1. Other aflatoxins were also detected in the oils. The measured levels indicate there is a need for food quality education among food processors.     

Natural co-occurrence of ochratoxin A,ochratoxin B and aflatoxins in Sicilian red wines

The natural occurrence of ochratoxin A, ochratoxin B, aflatoxin B₁, aflatoxin B₂, aflatoxin G₁ and aflatoxin G₂ (OTA, OTB, AFB₁, AFB₂, AFG₁, AFG₂) in red wines was investigated by HPLC/FLD after immunoaffinity column clean-up in 57 market samples produced in Sicily (Italy). The results showed a very low incidence of these mycotoxins in analysed samples, confirming the high degree of quality and safety of Sicilian red wines. The results indicated 71.9% and 64.9% positive samples for OTA and OTB respectively, with an average level of 0.13 μg l^–1, well below the European maximum permitted levels (MLs). The aflatoxin most frequently detected in the samples was AFG₁, present in 57.9% of samples, while the other aflatoxins were rarely present. Recovery experiments were carried out on eight mycotoxin-free red wines spiked with OTA, OTB, AFB₁, AFB₂, AFG₁ and AFG₂ at two different levels. The limits of detection (LODs) in wines were 0.02 µg l^–1 for OTA, 0.04 µg l^–1 for OTB, 0.03 µg l^–1 for AFG₁, AFG₂ and AFB₂, and 0.05 µg l^–1 for AFB₁. A good correlation was found, with good performances in term of precision for the method.     

Short communication: Investigation of aflatoxin M1 levels in infant follow-on milks and infant formulas sold in the markets of Ankara,Turkey

Aflatoxins are fungal toxins known to be carcinogenic and are classified as food contaminants. This study was performed to investigate aflatoxin (AF) M₁ levels in baby foods sold in Ankara (Turkey) and to evaluate the obtained results according to the Turkish Food Codex (TFC). For this purpose, a total of 84 baby food samples (50 follow-on milks and 34 infant formulas) were obtained from different markets in Ankara and the presence of AFM₁ in the samples was analyzed by ELISA. In 32 (38.1%) of 84 infant food samples, the presence of AFM₁ was detected in concentrations ranging between 0.0055 and 0.0201 µg/kg. The mean level (±standard error) of AFM₁ was found to be 0.0089 ± 0.0006 µg/kg in positive infant follow-on milks. Aflatoxin M₁ was detected in only 1 infant formula sample (2.94%) at a concentration of 0.0061 µg/kg. The extrapolated levels of AFB₁ contamination in feedstuffs were calculated based on levels of AFM₁ in baby food samples. The data estimating AFB₁ contamination in dairy cattle feedstuff indicate that contamination may range from 0.3410 to 1.2580 µg/kg, with the mean level (±standard error) being 0.5499 ± 0.0385 µg/kg, which is lower than the level set by the TFC and European Union regulations (5 µg/kg). According to the obtained results, the levels of AFM₁ in analyzed samples were within the allowed limit (0.025 µg/kg) set in the TFC. Low levels of AFM₁ in infant follow-on milks and infant formula samples obtained during the study do not pose a health risk to infants.     

低聚木糖作为牺牲剂在光催化产氢中的应用

目前光催化产氢的研究主要集中于修饰和改性半导体材料来提高其光催化产氢性能。在光催化分解水产氢过程中需要添加牺牲剂甲醇来消耗掉光生空穴,牺牲剂是影响半导体光催化剂产氢性能的一个重要因素。本研究选择可再生生物质低聚木糖作为牺牲剂,探讨了其光催化产氢性能,并与常用牺牲剂甲醇进行了光催化产氢性能比较。结果表明,未负载贵金属Pt时,半导体材料TiO2和C3N4进行光催化产氢时未检测到氢气。负载质量分数1%的Pt后,半导体材料Pt-TiO2和Pt-C3N4可以作为光催化剂进行产氢,经过24 h的光催化反应,基于催化剂质量,以甲醇为牺牲剂时分别产出4298. 3μmol/g和356. 5μmol/g的氢气,以低聚木糖为牺牲剂时分别产出3054. 5μmol/g和495. 6μmol/g的氢气。低聚木糖可以作为光催化产氢的牺牲剂,尤其用作Pt-C3N4的牺牲剂时,产氢性能优于甲醇。     

Intramolecular formation of cyclic ether by dehydration of 20(S)-ginsenoside Rg3

Two new conversion ginsenosides having cyclic ether together with ginsenoside Rg₅, Rk₁, and Rz₁ were isolated from dehydration products of 20(S)-ginsenoside Rg₃. On the basis of NMR spectroscopic analyses and comparison with spectral data of ginsenoside Rg₃ as a starting material, the chemical structures of two new ginsenosides were established as 12β-O-20(S)-ginsenoside Rg₃ and 12β-O-20(R)-ginsenoside Rg₃. The compounds were named as neoginsenoside L₁ and L₂ respectively. The conversion mechanism was expected to be accomplished by the formation of a tertiary carbocation or intramolecular nucleophilic displacement. The two new ginsenosides confirmed the existence from red ginseng extract by liquid chromatography.     

Urinary aflatoxin exposure monitoring in rural and semi-urban populations in Ogun state,Nigeria

Aflatoxins are a major class of fungal toxins that have food safety importance due to their economic and health impacts. This pilot aflatoxin exposure biomonitoring study on 84 individuals was conducted in a rural (Ilumafon) and a semi-urban community (Ilishan Remo) of Ogun state, Nigeria, to compare aflatoxin exposures among the two population cohorts. First morning urine samples were obtained from the participants, and the urinary aflatoxin M₁ (AFM₁) levels were measured by a quantitative Helica Biosystems Inc. ELISA kit assay. About 99% (83 out of 84) of the urine samples had detectable AFM₁ levels in the range of 0.06 to 0.51 ng mL^?1 (median: 0.27 ng mL^?1). The mean urinary AFM₁ levels were significantly (p = 0.001) higher in the semi-urban population (0.31 ± 0.09 ng mL^?1) compared to the rural population (0.24 ± 0.07 ng mL^?1). There were, however, no significant differences in mean urinary AFM₁ levels of males and females, and among children, adolescents and adults. This study indicates high aflatoxin exposure to the extent of public health concerns in the studied populations. Thus, more efforts are required for aflatoxin exposure monitoring and control in high-risk regions.     

不同清洗方法对皮蛋破损率影响的研究

目的探索一种可行的原料蛋清洗方式,以便在皮蛋生产中推广使用,满足皮蛋生产过程中的卫生要求。方法在其他工艺流程和工艺条件不变的情况下,采用5种不同的清洗方法对原料蛋进行清洗,并在一年中的4个不同时间,采用3种现有的腌制液腌制后对皮蛋破损率进行监测。结果皮蛋破损率受清洗方式的影响较大,使用传统工艺不清洗方式的破损率最低,经55~60℃热水清洗方式生产的皮蛋破损率次之,40~43℃温水清洗生产的皮蛋破损率最高。结论在腌制前,采用55~60℃热水对原料蛋的表面进行清洗是最有效降低皮蛋破损率的方式。