Dissipation of organophosphorus pesticides in wheat during pasta processing

For investigating the carryover of some organophosphorus pesticide residues in the cereal food chain from grain to consumer, a study was set up on durum wheat, semolina and pasta. Pesticide-free durum wheat was placed into a small-scale model of a commercial storage vessel and treated with pesticides (malathion, fenitrothion, chlorpyrifos methyl, and pirimiphos methyl) according to the raw material legislation of Turkey. The residue levels of insecticides were determined in wheat, semolina, and spaghetti produced from stored wheat at various time intervals during five months of storage. A multiresidue analysis was performed using GC equipped with an NPD. The confirmation was performed by GC–MS. The residue levels of insecticides in wheat exceeded the maximum residue limits (MRLs) for wheat. The storage period was generally not effective enough to reduce the residues in wheat to levels below the MRLs. Although a considerable amount of the insecticides remained in the semolina, spaghetti processing significantly reduced residue concentrations in general. Pirimiphos methyl was the most persistent of the insecticides and comparatively less substantial loss occurred during milling and spaghetti processing due to its physicochemical properties.     

Extraction of pesticide residues in tea by water during the infusion process.

The extraction rate of pesticide residues in water during the infusion process is dependent on the water solubility. The extraction of pesticide residues by boiling water can be regarded as a reversible equilibrium between adsorption and dissolution. The influence of chemical degradation is not important. When the water solubility is lower than 5 mg/kg, the extraction rate is 1-4%. Within the water solubility range of 10-150 mg/kg the extraction rate (Ri) is very sensitive to the water solubility (S); the relationship can be described as Ri = 59.8log S-42.5. When water solubility is higher than 170 mg/kg, the extraction rate is 90-100%.     

农药残留对普洱茶发酵中挥发性香气物质的影响

为了探究联苯菊酯农药残留对晒青毛茶益生菌发酵过程中挥发性香气物质的影响,采用同时蒸馏萃取（SDE）和气质联用（GC-MS）法分析喷洒联苯菊酯后2 h,人工接种黑曲霉（Aspergillus niger）、酿酒酵母（Saccharomyces cerevisiae）、产黄青霉（Penicillium chrysogenum）及对照（不接菌）4种固态发酵处理下普洱茶中挥发性香气成分。结果表明,与对照组相比,3种接种发酵条件下能有效增加1-石竹烯含量,且酵母菌发酵其增加量最高（192.4%）,芳樟醇、环氧芳樟醇（芳樟醇氧化物Ⅰ、Ⅱ）、α-松油醇等含量下降量最低（87.17%、22.06%、30.01%、91.40%）;长叶薄荷酮和三甲基乙酸香芹烯酯仅在3种接种发酵普洱茶中检测出。联苯菊酯不仅能影响晒青毛茶内含挥发性香气物质,还影响发酵过程中关键香气的形成和变化,而接种益生菌能改善和提升普洱茶的香气,其中接种酵母菌的普洱茶花果香显著,香气最好。     

茶叶中农药残留的检测

为了更好地解决茶叶中的农药残留问题,利用气相色谱仪(具电子捕获检测器)对茶叶中的α-HCH、β-HCH、γ-HCH、δ-HCH、ρ,ρ'-DDE、o,ρ'-DDT、ρ,ρ'-DDD和ρ,ρ'-DDT等农药的残留进行了测定,同时介绍了样品的处理方法,给出了测试的要求及部分样品测试的色谱图。结果表明:部分茶叶中有农药残留,总含量在100μg/L左右。     

Fate of imidacloprid and acetamiprid residues during black tea manufacture and transfer into tea infusion

The objective of this paper is to investigate the loss/stability of neonicotinoids (imidacloprid and acetamiprid) residues during the manufacture of black tea and to study the transfer of these pesticides from made tea to its infusion. For orthodox black tea, the manufacturing process involves leaf harvesting (plucking two leaves and a bud), withering, rolling, fermentation (oxidation), and drying. Initial withering and final drying resulted in the loss of pesticide residues, but no significant reduction in residue levels resulted from the rolling and fermentation steps. The drying process resulted in a residue transfer of 64–70% and 69–74% of the initial level, whereas the brewing process resulted in a residue transfer of 37–39% and 45–49% of imidacloprid and acetamiprid, respectively, from dried tea into the infusion. The decrease in acetamiprid levels during drying was also significant (8–13%), whereas the total loss during the manufacturing process ranged from 26 to 31%. Further, brewing for longer periods (an extended brewing time) resulted in higher transfer (up to 44% for imidacloprid and 53% for acetamiprid) of pesticides to tea infusion. Further, the extent of pesticide leaching depends on its water solubility, partition coefficient, and the brewing time.     

How manufacturing processes affect the level of pesticide residues in tea

Tea (both green and black) is consumed throughout the world, both for pleasure and therapeutic purposes. Most people will be unaware of their involuntary exposure to residues of pesticides lingering in processed tea and so possibly transferring into infusions of tea. The purpose of this work was to study the effect of green tea and orthodox black tea manufacturing processes on the fate of pesticides sprayed onto tea bushes (Camellia sinensis). The fates of residues of dimethoate, quinalphos, dicofol and deltamethrin in these two different types of tea manufacturing processes were compared. For black tea, the manufacturing process involves leaf harvesting, withering, rolling, fermentation and drying; and for green tea, leaf harvesting, microwave heating, rolling and drying. The two processes resulted in the same concentration factor of plant material into the dried commodity, while the decreases in residue levels were different for different pesticides. Initial microwave heating and dehydration in the green tea manufacturing process resulted in greater loss of pesticide residues than did withering and dehydration in black tea; no significant reduction in residue level resulted from the rolling and fermentation steps in black tea. Residue levels in both green and black teas were reduced during final drying. Copyright © 2004 Society of Chemical Industry     

气相色谱-质谱联用法测定茶叶中21种农药残留

该实验建立了茶叶中21种农药残留的气相色谱-质谱（GC-MS）多反应监测模式（MRM）定性、定量分析检测方法,探讨不同 提取方法、提取溶剂、浓缩方式等试验因素对茶叶农药多残留测定结果的影响。 结果表明,以正己烷-丙酮（1∶1,V/V）混合溶剂超声提 取、氮吹浓缩,用气相色谱-质谱法对茶叶样品中21种农药进行定性定量检测,21种农药在0.05～1.00 μg/mL范围内呈良好的线性 关系,相关系数（R2）为0.998 0～0.999 9。 在茶叶样品中分别添加质量浓度0.05 mg/kg、0.20 mg/kg、0.40 mg/kg的农药组分,平均回收率 为83.46%～92.13%,相对标准偏差（RSD）为4.88%～8.51%,检出限为0.002 7～0.021 9 mg/kg,该方法具有前处理简便快捷、灵敏度 高、成本低等优点,在实际茶叶农药残留检测中得到了广泛应用,能满足日常的茶叶农药残留检测。     

气相色谱-串联质谱法测定茶叶茶汤中多种农药残留量

目的采用Qu ECh ERS方法和气相色谱-串联质谱(gas chromatography-tandem mass spectrometry,GC-MS/MS)分析技术,建立茶叶茶汤中65种不同极性农药残留量的快速检测方法。方法利用乙腈(含1%乙酸)提取茶叶茶汤样品,分散固相萃取法净化样品,GC-MS/MS检测采用选择反应监测模式(selective reactions monitoring,SRM),灵敏度最高的离子对用作定量。结果 65种农药在3个浓度添加水平上的加标回收率范围是76%~134.6%,相对标准偏差(RSD,n=6)范围为1.0%~18.41%,茶叶样品定量限是0.15~3.0μg/kg,茶汤样品定量限是0.1~1.5μg/kg。结论该方法灵敏度高,准确性好,快速简便,适用于绿茶、乌龙茶、白茶和红茶中多种农药残留量的检测。     

QuEChERS 方法在茶叶农药残留检测中的应用研究进展

茶叶的农药残留检测关系到茶叶的质量安全。茶叶样品基质复杂,干扰物质多,其样品前处理是农药残留检测过程中耗时最长、工作量最大的部分,前处理技术的好坏也决定着分析的准确性和精密度。QuEChERS(quick, easy, cheap, effective, rugged, safe)方法作为一种农药多残留分析的前处理方法,由于具有快速、简单、廉价、有效、可靠、安全的特点而成为近年来的研究热点。本文就QuEChERS方法及其在茶叶农药残留检测中的应用研究进展进行评述。     

Comparison of the relative dissipation rates of endosulfan pesticide residues between oolong and green tea

The dissipation behaviour of endosulfan in dry made-tea leaves of oolong and green tea was compared to establish whether there was any difference in dissipation rates between the two teas. The dissipation of endosulfan in oolong and green tea corresponded with a first-order kinetics curve. The average half-life of endosulfan (n = 12) was 1.60 ± 0.44 days in green tea and 2.01 ± 0.55 days in oolong tea, showing a statistically significant difference, and indicating that the dissipation of the pesticide was significantly slower in oolong tea than that in green tea. Although the initial levels of residual endosulfan were lower in oolong tea, due to the slower dissipation rate, the residues 5-7 days after application were higher in oolong than in green tea. It is suggested that the minimum interval between endosulfan application and tea leaf harvesting is 7 days for green tea and 10 days for oolong tea in the case where the maximum residue limit of endosulfan in made-tea is fixed as 10 mg kg^-1.     

宜昌茶叶中农药残留监测及分析

目的监测茶叶农药残留情况,了解宜昌茶叶质量安全现状。方法采集的样品经过Qu ECh ERS方法进行提取、净化,采用气相色谱-串联质谱法(gas chromatography-tandem mass spectrometry,GC-MS/MS)对宜昌市茶叶主产区125批次茶叶样品中25种农药残留进行监测分析,外标法定量。结果所有监测样品中,农药检出39批次,涉及农药6种,检出率31.2%。结论按照GB 2763-2017标准,所检出样品没有超标样品。国家标准缺乏茶叶中部分农药残留最大限量标准,需要进一步完善。     

Comparison of the relative dissipation rates of endosulfan pesticide residues between oolong and green tea

The dissipation behaviour of endosulfan in dry made-tea leaves of oolong and green tea was compared to establish whether there was any difference in dissipation rates between the two teas. The dissipation of endosulfan in oolong and green tea corresponded with a first-order kinetics curve. The average half-life of endosulfan (n = 12) was 1.60 ± 0.44 days in green tea and 2.01 ± 0.55 days in oolong tea, showing a statistically significant difference, and indicating that the dissipation of the pesticide was significantly slower in oolong tea than that in green tea. Although the initial levels of residual endosulfan were lower in oolong tea, due to the slower dissipation rate, the residues 5–7 days after application were higher in oolong than in green tea. It is suggested that the minimum interval between endosulfan application and tea leaf harvesting is 7 days for green tea and 10 days for oolong tea in the case where the maximum residue limit of endosulfan in made-tea is fixed as 10 mg kg^?1.     

信阳茶叶农药残留检测及其风险评估

目的 了解信阳地区茶叶农药残留情况及其风险程度.方法 2013—2020年连续8年收集信阳地区茶叶样品132个,在同一年按照国家标准、农业行业标准等规定的农药测定方法进行测定.运用危害物风险系数法进行农残风险评估.结果 132个信阳茶叶样品中,检测出农药残留样品100个,农药残留检出率为75.76％,共检测到农药种类1...     

分散液液微萃取-超高效液相色谱-串联质谱法测定市售凉茶中6种有机磷农药残留

目的建立分散液液微萃取-超高效液相色谱-串联质谱法测定凉茶中6种有机磷残留量的方法。方法样品经N-丙基乙二胺(N-Propylethylenediamine,PSA)固相萃取剂预净化后,以甲醇为分散剂,三氯甲烷为萃取剂进行提取。在优化后的仪器条件下,采用电喷雾离子化正离子模式电离,多反应监测模式进行测定。结果 6种有机磷的标准曲线在2.0～200μg/L范围内线性良好,相关系数r2均大于0.9990,在添加水平为0.25、0.50和2.5μg/kg的加标回收试验中,平均回收率范围为73.6%～99.5%,相对标准偏差为1.14%～8.01%,方法检出限和定量限为0.02～0.04μg/kg和0.06～0.10μg/kg。结论该方法操作简单便捷、富集倍数高、灵敏度高、重现性好,可用于实际市售凉茶产品的质量监督。     

气相色谱法检测茶饮料中4种残留农药

目的 建立利用固相萃取-气相色谱法同时测定茶饮料中乐果、腐霉利、哒螨灵、高效氯氰菊酯4种农药的分析方法.方法 考察了提取剂、固相萃取柱对检测的影响.样品采用乙腈提取,经弗罗里硅土柱净化,色谱柱采用Rtx-5(30 m×0.25 mm×0.25 μm).结果 4种农药的线性良好,相关系数为0.999 4～0.999 9,加标回收率为88.76％ ～ 102.4％,相对标准偏差小于5％,检测限在0.001～0.01mg/kg之间.结论 该操作简单,节约了时间与有机溶剂,为饮料中多残留分析提供参考.     

含多种农药残留的茶叶自然污染基质标准样品的研制

目的 建立了基于药物代谢的含多种农药残留的茶叶基质标准物质的研制与定值方法。方法 在茶树种植过程中喷施农药,使药物在茶树中自然代谢,从而获得有农药残留的自然污染样本,比较了不同制茶工艺及辐照灭菌对农药残留的影响,经均质、真空包装及辐照处理,获得了一批含有多种农药残留的茶叶自然污染样本。结果 经均匀性和稳定性检验,表明样本在最小取样量下的瓶间及瓶内均匀性良好,室温下可稳定保存至少60日。结论 所研制的标准样品为自然污染的茶叶,与日常检测样品基质完全一致,可应用于相关检测方法的开发、验证和检测结果的质量控制等。     

茶皂素对草莓农药残留去除效果的研究

使用清水、质量浓度5%茶皂素溶液和稀释3 000倍的洗洁精对草莓进行清洗后,通过气相色谱对草莓中的农药残留含量进行检测。试验结果显示,质量浓度5%的茶皂素溶液对水溶性和脂溶性的农药去除效果均优于清水和稀释3 000倍的洗洁精,可以显著的降低草莓中的农药残留含量。结果表明,质量浓度5%茶皂素溶液对农残的洗涤效果较优,具有开发成果蔬洗涤剂的价值。     

茶叶中4种菊酯类农药的气相色谱分析方法

目的 建立了茶叶中菊酯类农药残留量的气相色谱分析方法.方法 采用丙酮:石油醚=1∶1(V/V)作为提取剂,石英毛细管柱、电子捕获检测器、外标法定量,分析茶叶中甲氰菊酯、氯氰菊酯、氰戊菊酯、溴氰菊酯农药的残留量.结果 甲氰菊酯的回收率为82.7％～101.3％,RSD为2.19％ ～5.46％;氯氰菊酯的回收率为81.7％ ～102.5％,RSD为2.11％ ～5.63％;氰戊菊酯的回收率为85.3％ ～ 103.6％,RSD为2.04％ ～4.29％;溴氰菊酯的回收率为86.1％ ～ 102.3％,RSD为1.98％ ～5.25％.结论 气相色谱分析方法准确可靠,适用于市售各种茶叶中菊酯类农药残留量的分析.     

QuEChERS-气相色谱串联质谱法同时测定茶叶中6种农药残留

目的:建立基于QuEChERS-气相色谱串联质谱法(GC-MS/MS)同时检测茶叶中烯虫乙酯、烯虫炔酯、格螨酯、氟除草醚、环螨酯、草枯醚6种农药残留的分析方法。方法:样品经QuEChERS前处理后,采用气相色谱分离、多反应监测(MRM)模式进行检测,外标法定量。结果:6种农药在0.025～2.000 mg/kg的质量浓度范围内线性良好,相关系数均>0.999,检出限为0.000 6～0.007 2 mg/kg。在0.002 5,0.05,1.0 mg/kg 3个水平的加标回收试验中,回收率为84.3%～116.3%,相对标准偏差(RSD)为1.07%～6.15%。结论:该方法快速、简便、准确,适用于茶叶中6种农药残留检测。