QuEChERS-液相色谱-串联质谱法测定牛蛙肉中酰胺醇类抗生素及其代谢物

采用QuEChERS技术提取氯霉素、甲砜霉素、氟苯尼考及其代谢物氟苯尼考胺,建立液相色谱-串联质谱法（liquid chromatography-tandem mass spectrometry,LC-MS/MS）同时测定牛蛙肉中酰胺醇类抗生素及其代谢物的检测方法。结果表明：在0.1～50.0 ng/mL范围内,酰胺醇类抗生素及其代谢物质量浓度与其质谱响应值呈良好的线性关系,相关系数均大于0.999 1;检出限为0.007 5～0.003 0 μg/kg,定量限为0.025～0.100 μg/kg;加标回收率为94.3%～97.9%,相对标准偏差为0.8%～3.7%。     

液相色谱-质谱法测定乳及乳制品中氯霉素类抗生素的含量

目的建立液相色谱-质谱法测定乳及乳制品中氯霉素类抗生素的残留量。方法液态奶、酸奶、奶粉样本经乙酸乙酯提取,经Waters Sep-pak C_(18)固相萃取小柱净化,至Agilent C_(18)(150 mm×2.1 mm,5μm)色谱柱分离,以乙腈:水(50:50,V:V)为流动相进行等度洗脱。质谱法采用电喷雾离子源负离子模式和多反应监测模式测定,以内标法定量。结果氯霉素、甲砜霉素、氟苯尼考3种待测物质在0.1~20 ng/m L范围内线性关系良好,线性相关系数都在0.9995以上;氯霉素的检出限为0.011~0.021μg/kg,甲砜霉素的检出限为0.042~0.100μg/kg,氟苯尼考的检出限为0.010~0.018μg/kg;氯霉素在0.05、0.5和1μg/kg 3水平上的加标回收率为83.1%~95.6%,甲砜霉素在0.1、1和2μg/kg 3水平上的的加标回收率为80.2%~102.1%,氟苯尼考在0.05、0.5和1μg/kg 3水平上的的加标回收率为81.3%~103.5%;氯霉素的相对标准偏差为4.4%~6.4%,甲砜霉素的相对标准偏差为4.1%~7.1%,氟苯尼考的相对标准偏差为3.7%~6.6%。结论本方法准确灵敏,适用于乳及乳制品中氯霉素类抗生素残留量的测定。     

超高效液相色谱-串联质谱法测定鸡肉、鸡蛋中氟苯尼考和氟苯尼考胺残留

目的建立超高效液相色谱-串联质谱准确测定鸡肉、鸡蛋中氟苯尼考和氟苯尼考胺残留的分析方法。方法鸡肉和鸡蛋样品加入D5-氯霉素内标,经氨化乙酸乙酯混合溶液超声离心提取,提取液减压蒸馏浓缩后,C18固相萃取柱净化处理,采用超高效液相色谱-串联质谱法对氟苯尼考和氟苯尼考胺同时进行检测。结果氟苯尼考线性范围为0.2～20μg/L,检出限为1.0μg/kg,定量限为3.0μg/kg,方法回收率为88.0%～108.0%,相对标准偏差为4.7%～6.4%;氟苯尼考胺线性范围为0.2～20μg/L,检出限为1.0μg/kg,定量限为3.0μg/kg,方法回收率为76.0%～93.1%,相对标准偏差为4.1%～7.2%。结论本方法精确、重现性好,适用于鸡肉、鸡蛋中氟苯尼考和氟苯尼考胺残留量的测定。     

UPLC-MS/MS测定啤酒中茚嗪氟草胺及其代谢物残留量

该实验建立了基于分散固相萃取结合超高效液相色谱-串联质谱技术（UPLC-MS/MS）对啤酒中的茚嗪氟草胺及其3种代谢物残留量的测定方法。样品经乙腈提取后进行盐析分层,离心后乙腈层用C18固相萃取剂净化后,于电喷雾离子源正离子（ESI+）模式下采集碎片信息。结果表明,茚嗪氟草胺及其3种代谢物的基质曲线在1.0～50.0 μg/L的质量浓度内呈良好线性关系,相关系数（R2）均大于0.999,平均加标回收率为85.4%～98.1%,精密度试验结果的相对标准偏差（RSD）为2.29%～4.55%。方法检出限（LOD）和定量限（LOQ）分别为2.0 μg/kg和5.0 μg/kg。该方法快速高效,回收率、灵敏度高,重复性好,可有效测定啤酒中茚嗪氟草胺及其代谢物的残留量。     

GC-MS检测蜂蜜中双甲脒残留量的方法研究

试验通过改变提取溶剂体积和前处理步骤,建立了一种快速、节约、高效的GC-MS检测蜂蜜中双甲脒残留量方法。经验证,该方法检出限为17.2μg/kg,定量限为57.3μg/kg,在20~320 ng/mL线性范围内双甲脒及其代谢物的峰面积与浓度呈良好线性关系,相关系数达0.999以上。当加标浓度在80 ng/mL时,双甲脒回收率达到92.8%~99.1%,2,4-二甲基苯胺回收率达到84.6%~88.9%。在600μg/kg含量水平下连续测定6针,其相对标准偏差为0.816%。该方法简单可靠,适合实验室进行样品的批量处理。     

超高效液相色谱-串联质谱法同时测定水产品中4种酰胺醇类抗生素残留

目的 建立了一种超高效液相色谱-串联质谱同时测定水产品中酰胺醇类抗生素氯霉素、甲砜霉素、氟苯尼考及代谢物氟苯尼考胺的方法。方法 水产品样品经乙腈提取,正己烷除脂后,在Capcell Pak ADME (100×2.1 mm, 2.7 μm, 1.7 ?m)色谱柱上分离,于多反应监测模式,以氯霉素-D5和氟苯尼考胺-D3为内标进行定量测定。结果 氯霉素在0.5～25 ng/mL范围内线性关系良好（r>0.999）,甲砜霉素、氟苯尼考和氟苯尼考胺在5～250 ng/mL范围内线性关系良好（r>0.998）。方法检测限为0.1~1.0 μg/kg,定量限为0.2~2.0 μg/kg。当氯霉素添加水平为0.2、1和10 μg/kg时,回收率为82.5%～104%,相对标准偏差在2.2%~11.8%之间;当甲砜霉素、氟苯尼考和氟苯尼考胺添加水平为2、10和100 μg/kg时,回收率为80.9%～102%,相对标准偏差在0.8%~8.4%之间。结论 该方法快速简单,准确,成本低,适用于水产品中酰胺醇类抗生素及代谢物残留的检测。     

内标液相色谱-串联质谱法测定蜂蜜中氯霉素、甲砜霉素和氟苯尼考残留

目的建立液相色谱-串联质谱法测定蜂蜜中氯霉素、甲砜霉素和氟苯尼考的分析方法。方法以氯霉素-D5为内标,样品用乙酸乙酯提取,提取液在45℃氮气吹至近干,残渣用2mL水溶解,溶解液过Oasis HLB柱净化,洗脱液在45℃氮气吹干, 50%甲醇水溶液定容,后经正己烷脱色脱脂、PSA粉末吸附净化,高速离心过膜后用串联四极杆检测。样液经过Agilent Eclipse XDB-C₁₈色谱柱分离,甲醇-水流动相梯度洗脱,多反应监测扫描模式检测。采用内标法定量。结果氯霉素在0.1~4.0μg/kg、甲砜霉素和氟苯尼考在0~40.0μg/kg呈良好的线性关系,相关系数大于0.999,回收率为93.7%~109.7%,RSD为0.7%~11.4%,检出限为0.03~0.09μg/kg,定量限为0.1~0.3μg/kg。结论该方法准确、检出限低、重现性好,适用于蜂蜜中氯霉素、甲砜霉素和氟苯尼考残留的检测。     

SPE结合超高效液相色谱-质谱/质谱仪测定鸡蛋中的万古霉素和去甲万古霉素残留量

建立了固相萃取法(SPE)结合超高效液相色谱-质谱/质谱仪(UPLC-MS/MS)测定鸡蛋中万古霉素和去甲万古霉素残留量的方法。样品采用0.1%甲酸水溶液进行提取,Strata-X-C固相萃取柱进行净化,UPLC-MS/MS正离子模式扫描,多反应监测模式(MRM)测定,外标法定量。结果表明:万古霉素和去甲万古霉素在5.0~100.0 μg/L浓度范围线性关系良好(r均大于0.999),检出限为2.0 μg/kg,定量限为5.0 μg/kg,加标平均回收率为85.6%~96.3%,相对标准偏差为3.7%~9.2%。该方法灵敏度高,准确度好,能满足对鸡蛋中万古霉素和去甲万古霉素定量分析的要求。     

QuEChERS-UPLC-MS/MS法测定鸡蛋中19种氨基甲酸酯类农药及其代谢物残留量

采用QuEChERS-超高效液相色谱-串联质谱法（UPLC-MS/MS）同时测定鸡蛋中的19种氨基甲酸酯类农药及其代谢物残留量。鸡蛋样品通过乙腈提取,分散固相萃取净化,UPLC-MS/MS测定。19种氨基甲酸酯类农药及其代谢物残留在0.2~50 ng/mL范围内线性良好（R2>0.999）,方法的检出限为1.0~10 μg/kg。在添加水平为10、20、50 μg/kg时,回收率为69.3%~107.6%,相对标准偏差低于9.21%。该方法简单快速,高效准确,回收率高,能够满足鸡蛋中19种氨基甲酸酯类农药及其代谢物残留检测与确证的需要。     

UPLC-MS/MS法测定禽蛋中氟苯尼考及氟苯尼考胺

建立一种超高效液相色谱-串联质谱法同时测定禽蛋中氟苯尼考(FF)和氟苯尼考胺(FFA)含量的方法。样品经2%氨水-乙酸乙酯提取,PRiME HLB固相萃取(SPE)柱净化。采用Hypersil GOLD C18色谱柱(100 mm×2.1mm,1.9μm),以乙腈(B1)-0.1%甲酸水(A2)为流动相进行梯度洗脱。氟苯尼考和氘代氟苯尼考采用电喷雾负离子源,氟苯尼考胺采用电喷雾正离子源,多反应监测模式,以氘代氟苯尼考(氟苯尼考-d3)为氟苯尼考进行内标定量,氟苯尼考胺外标法定量。结果表明,氟苯尼考和氟苯尼考胺在0.2~10μg/L范围内均呈良好线性关系(r≥0.9978)。加标浓度分别为0.1,0.2和1μg/kg及0.5,1.0和5.0μg/kg,回收率分别在91.0%~100.9%和73.7%~84.3%之间,相对标准偏差均<3.52%(n=6)。氟苯尼考的检出限和定量限分别为0.05μg/kg和0.1μg/kg,氟苯尼考胺的检出限和定量限分别为0.25μg/kg和0.5μg/kg。该方法准确、灵敏、快速,能有效并同时检测禽蛋中氟苯尼考和氟苯尼考胺含量。     

水稻中除草剂氯氟吡氧乙酸异辛酯和氰氟草酯的检测方法及其储藏稳定性研究

目的 探究26%氰氟草酯·氯氟吡氧乙酸异辛酯乳油在水稻上的残留行为, 对其储藏稳定性和膳食摄入风险进行评估。方法 待测试样经乙酸乙腈提取, N-丙基乙二胺(primary secondary amine, PSA)、C18和石墨化碳黑(graphitized carbon black, GCB)净化, 再经高效液相色谱-串联质谱法多反应监测模式扫描, 基质匹配标准曲线外标法定量。2018年在9地进行田间残留实验, 并且进行6个月的储藏实验, 获得氯氟吡氧乙酸、氰氟草酯和氰氟草酸在水稻上的残留实验中值、降解率, 对膳食摄入风险进行评估。结果 氯氟吡氧乙酸、氰氟草酯和氰氟草酸在加标浓度为0.05~0.5 mg/kg范围内具有良好的线性关系, 相关系数(r)为0.9984, 3种待测物在水稻中的平均回收率为76.4%~105.0%, 相对标准偏差(relative standard deviation, RSD)为1.2%~8.2%, 定量限为0.05 mg/kg。在6个月储藏实验期间, 3种待测物在稻谷及水稻植株的降解率低于30%。膳食风险评估表明: 普通人群氯氟吡氧乙酸异辛酯、氰氟草酯的国家估计每日摄入量分别为0.0596 mg和0.0120 mg, 膳食摄入风险评估分别为4.73%和1.90%。结论 该检测方法操作简便、前处理速度快、精密度高和灵敏度高, 可以满足对复合农药残留分析检测的要求。氯氟吡氧乙酸、氰氟草酯和氰氟草酸在-20 ℃冰箱6个月储藏稳定, 其在水稻上的残留对消费者不会产生不可接受的风险     

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.     

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.     

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。     

Degradation of aflatoxin B1 by fungal laccase enzymes

The enzymatic degradation of aflatoxin B₁ (AFB₁) by white rot fungi through laccase production was investigated in different liquid media. A significant (P < 0.0001) correlation was observed between laccase activity and AFB₁ degradation exhibited by representatives of Peniophora and Pleurotus ostreatus cultivated in minimal salts (MSM) (r = 0.93) and mineral salts — malt extract (MSB–MEB) (r = 0.77) liquid media. Peniophora sp. SCC0152 cultured in MSB–MEB liquid medium supplemented with veratryl alcohol and sugarcane bagasse showed high laccase activity (496 U/L), as well as 40.45% AFB₁ degradation as monitored using high performance liquid chromatography. P. ostreatus St2-3 cultivated in MSM liquid medium supplemented with veratryl alcohol resulted in laccase activity of 416.39 U/L and 35.90% degradation of AFB₁. Aflatoxin B₁ was significantly (P < 0.0001) degraded when treated with pure laccase enzyme from Trametes versicolor (1 U/ml, 87.34%) and recombinant laccase produced by Aspergillus niger D15-Lcc2#3 (118 U/L, 55%). Aflatoxin B₁ degradation by laccase enzyme from T. versicolor and recombinant laccase enzyme produced by A. niger D15-Lcc2#3 coincided with significant (P < 0.001) loss of mutagenicity of AFB₁, as evaluated in the Salmonella typhimurium mutagenicity assay. The degradation of AFB₁ by white rot fungi could be an important bio-control measure to reduce the level of this mycotoxin in food commodities.     

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.     

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.