液相色谱-串联质谱法测定牛奶中11种光引发剂残留量

建立了牛奶中11种光引发剂残留的定性和定量测定分析方法。样品经Carrez试剂沉淀蛋白质后,使用乙腈提取,HLB固相萃取柱净化,乙腈洗脱,洗脱液用氮气吹干后用50%乙腈水溶液定容,采用液相色谱-串联质谱进行测定。分析物采用电喷雾电离,正离子扫描,多反应监测(MRM)模式检测,其中7种光引发剂使用内标法定量,4种光引发剂使用外标法定量。11种光引发剂在5.00～200μg/L浓度范围内线性关系良好,相关系数均大于0.990。11种光引发剂的测定低限均为1.0μg/kg。在添加浓度1.00～100μg/kg范围内,加标回收率为74.3%～112%,相对标准偏差为0.57%～16.3%。本方法简便、有效、灵敏,适用于牛奶中光引发剂多残留的定量测定和确证。     

Straw coverage alleviates seasonal variability of the topsoil microbial biomass and activity

Straw coverage on soil surface is a well-known practice for conserving soil and water. Seasonal variability of microbial biomass carbon (MBC) and basal respiration (BR) in surface soil (0–5 cm) was compared between conventional straw removal (SR) and straw coverage (SC) in a maize (Zea mays L.) field experiment, Northeast China. The straw coverage treatment significantly increased microbial energy, carbon and nutrient sources (soil C and N contents) and improved soil physical environment (moisture and porosity), and thus stimulated MBC and BR across the growth season of maize, as compared to the straw removal treatment. MBC and BR showed similar seasonal trends in soil temperature, with maximum values in summer. In both study years, the straw coverage treatment reduced seasonal variation of soil temperature, therefore it significantly moderated seasonal variability of MBC and BR. Our results demonstrate that straw coverage contributes to stabilizing soil microbial characteristics in season.     

Differential and successive effects of residue quality and soil mineral N on water-stable aggregation during crop residue decomposition

Residue quality has been shown to influence soil water-stable aggregation (WSA) during crop residue decomposition, but there is still little information about its interactive effect with soil mineral N availability. The aim of this study was to determine the effect of soil mineral N on WSA during the decomposition of two high-C/N crop residues (wheat straw with C/N = 125.6 and miscanthus straw with C/N = 311.3). The two crop residues were combined with three mineral N addition rates (0, 60, and 120 mg N kg⁻¹ dry soil). Respiration, soil mineral N content, and WSA (expressed as mean-weight diameter, MWD) were measured on several dates during a 56-d incubation. The effect of decomposing crop residues on WSA followed two phases. (i) Between 0 and 7 d, the increase in WSA was related to intrinsic residue quality with higher decomposability of the wheat straw resulting in higher WSA. (ii) Thereafter, and until the end of the experiment, mineral N addition rates had a predominant but negative influence on WSA. In this second phase, the average MWD of residue-treated soils was 0.92, 0.55, and 0.44 mm for the 0, 60 and 120 mg N kg⁻¹ dry soil addition rates, respectively. Mineral N addition which did result in higher crop residue decomposition did not lead to higher WSA. WSA during crop residue decomposition is therefore not simply positively related to the induced microbial activity, and changes in microbial community composition with differential effects on WSA must be involved. The impact of high-C/N crop residues inputs on WSA, initially assumed to be low, could actually be strong and long-lasting in situations with low soil mineral N content.     

家禽肌肉组织中硝基咪唑类药物残留高效液相色谱检测法研究

 建立了检测家禽肌肉组织中甲硝唑、洛硝哒唑、二甲硝咪唑残留的高效液相色谱法。样品经乙酸乙酯振荡提取 ,浓缩 ,盐酸溶解残渣 ,己烷萃取除去脂肪。氢氧化钠调节溶液到pH 4 .8～ 5 .2 ,过C18小柱 ,甲醇洗脱 ,SpherisorbC18柱分离 ,32 0nm处检测。流动相为醋酸缓冲液 乙腈 (85∶15 ,v/v)。甲硝唑、洛硝哒唑和二甲硝咪唑检测限分别为 0 .5、1.0和 1.0ng·g-1。肉鸡肌肉组织中添加 6 .0ng·g-1水平回收率分别为 :甲硝唑 89.8% ,洛硝哒唑81.7% ,二甲硝咪唑 86 .6 %。此方法具有定性合理 ,检测限低 ,分析快速 ,准确等特点。     

秸秆发电和气化残余物作为肥料在水稻生产上的应用研究

秸秆发电和气化残余物(下称草木灰),其含有丰富的大量和中微量元素,如K、Ca、P、Mg、Si、Cu、Zn、B等,其中钾含量尤为丰富。而水稻是一种喜钾和硅的作物。将草木灰作为钾肥应用于水稻的生产上,一方面可节约生产成本,另一方面还可以改善大米的品质;但草木灰同时还含有重金属元素,过量的施入势必会带来土壤环境的恶化,本文通过分析土壤中和大米中重金属含量的变化,得出本试验中草木灰的施入不会引起环境的恶化;从生产成本和水稻产量与品质上综合考虑得出处理木灰1 50%替代化学钾肥和草木灰2 75%替代化学钾肥是最佳施肥处理。     

油菜体内及土壤中咪鲜胺的残留检测与消解动态

采用固相萃取( SPE) - 高效液相色谱紫外检测(HPLC - UV)建立了油菜中咪鲜胺的残留量检测方法,并 进行咪鲜胺消解动态研究。提取液经石墨碳和C18固相萃取柱净化、浓缩后测定。咪鲜胺在各样品中的添加回收 率为80. 1% ～91. 8% ,变异系数为1. 8%～9. 6%。咪鲜胺在油菜中消解较快,半衰期为4～6d; 30g制剂/666. 7m2 于油菜盛花期施药2 次,油菜收获时,油菜籽中咪鲜胺残留量最高为0. 20mg/kg,土壤中咪鲜胺残留量最高为 0. 49mg/kg。     

液相色谱-串联质谱法检测猪肉中20种违禁药物残留的研究

建立了猪肉中违禁药物（糖皮质激素、性激素、β2-肾上腺素受体激动剂、玉米赤霉烯酮4类）同时测定的高效液相色谱-串联质谱方法。试样经盐酸水解,乙酸乙酯提取,低温冷冻去除脂类,亲水亲脂平衡固相萃取柱净化。采用C18反相色谱柱分离,以乙腈+水为流动相梯度洗脱,分别在电喷雾离子源正、负离子模式下以多反应监测模式（MRM）分段扫描同时检测,基质匹配内标法定量。结果表明,20种违禁药物在相应的浓度范围内线性良好,相关系数均大于0.99;该方法在猪肉中的检测限（LOD,S/N=3）和定量限（LOQ,S/N=10）分别为0.5、1.0 μg/kg。在0.5~10 μg/kg添加浓度水平下,平均回收率为63.9%~117%,批内变异系数1.9%~9.1%,批间变异系数4.9%~13.1%。该方法简单、快速、准确,适用于猪肉中多类违禁药物的残留检测。     

灰黄霉素在家兔组织中的分布及残留消除规律研究

研究灰黄霉素在家兔组织中的分布及消除规律,为灰黄霉素用于治疗家兔真菌病的安全性评价提供依据。选择42只新西兰白兔,于饲料中添加灰黄霉素（800g／1000kg）混饲,连续饲喂14d,分别于停药后1、3、5、7、9、14、21d,各处死6只,取其肝、肾、肌肉、皮肤及脑组织。以盐酸普萘洛尔为内标,二氯甲烷提取后用高效液相色谱-串联质谱仪（HPLC—MS／MS）进行各种组织中灰黄霉素浓度分析。结果显示,连续用药14d后,灰黄霉素在家兔组织中的分布情况为：肝组织浓度最高（134．61μg／kg）,肾组织次之（54．09μg／kg）,脑组织浓度最低（未检出）;停药后,随着时间的延长,灰黄霉素在肌肉、肝、肾和皮肤组织中的浓度逐渐下降,且在肝脏中的消除速度最快,停药21d后,灰黄霉素在肾组织中浓度为3．39μg／kg,在肝组织中浓度为12．36μg／kg,其他组织低于定量限或未检出。建议家兔生产中慎用灰黄霉素。     

气相色谱/质谱(GC/MS)测定蔬菜中甲基对硫磷农药和呋喃丹的优化

利用气相色谱/质谱(GC/MS)同时测定及确定蔬菜中甲基对硫磷农药和克百威(呋喃丹)的残留量。研究了振荡提取时间、提取剂用量、盐加入量、浓缩条件等操作条件对分析方法的影响。得到的优化分析条件如下:振荡提取时间为90 min、提取剂用量为70 mL、盐加入量为3 g、浓缩条件为温度50℃低压0.09 atm;该方法的相对标准偏差<10%,样品的加标回收率为甲基对硫磷82.5%、克百威为93.5%。本方法可以满足这2种杀虫剂在蔬菜中的检测要求。     

不同水热处理对刨花板苯酚液化效果的影响

对实验室自制刨花板和回收废弃刨花板分别进行水热处理,在两种不同的液化条件下对处理的刨花板粉进行液化,利用液化残渣率为指标,分析不同水热条件处理对刨花板苯酚液化的影响。在不同的液化条件下得出相同的结果:同一水热处理时间下,两种刨花板的液化残渣率都随着温度的升高而呈现降低的趋势;同一水热处理温度下,液化残渣率也随着处理时间的增加而呈现降低的趋势,水热处理温度比水热处理时间对刨花板苯酚液化的影响效果大。对实验结果进行数据分析得到较理想的最佳水热处理条件是:实验室自制刨花板水热温度80℃,水热处理时间6h;回收废弃刨花板水热温度80℃,水热处理时间8h。