镀铋膜修饰玻碳电极方波伏安法测定豆芽中痕量铬

采用铋膜电极方波伏安法测定豆芽中痕量铬.通过正交试验优化Cr(VI)的测定条件,在最优参数下,Cr(VI)的浓度在0.1 μg/L～200 μg/L范围内与峰电流呈良好的线性关系;Cr(Ⅵ)的检测限为0.001 μg/L.在最佳检测条件下,测定铬的含量为2.824 mg/kg.试验相对标准偏差<10%,回收率在90%～110%之间.结果令人满意,具有很高的实际应用价值.     

酒花萜烯醇及其立体异构体在啤酒酿造中的检测及其变化研究

采用顶空固相微萃取-气相色谱质谱技术(HS-SPME/GC-MS),跟踪检测了啤酒酿造过程中(R)-(-)-里那醇、S-(+)-里那醇、(R)-(+)-β-香茅醇、(S)-(-)-β-香茅醇、(+)-α-萜品醇、(-)-α-萜品醇、香叶醇、橙花叔醇等12种香气化合物。通过控制酿造过程中不同的香花添加工艺,发现在煮沸结束、回旋沉淀槽及主酵结束后添加香花工艺较煮沸结束前10 min添加工艺,能显著提高萜烯醇及其立体异构体保留在啤酒中的含量,其中对酒花香气具有重要贡献的四种萜烯醇:R-(-)-里那醇、香叶醇、R-(+)-β-香茅醇及橙花叔醇在啤酒中的含量范围分别为1.94¹4.39μg/L、9.8314.39μg/L、9.83¹2.10μg/L、2.9112.10μg/L、2.91⁶.79μg/L、5.346.79μg/L、5.34⁶.81μg/L,它们的风味强度OAV值范围在0.296.81μg/L,它们的风味强度OAV值范围在0.29⁶.54,并对上述4种物质在啤酒发酵过程中的变化规律展开了进一步探究。结合感官评品结果显示,发现回旋沉淀槽添加香花工艺最好,主酵结束后添加香花工艺次之。     

固相萃取净化-高效液相色谱测定水果中赤霉素、多效唑、烯效唑残留量

建立了一种简单、快速,同时检测水果中赤霉素、多效唑和烯效唑残留量的固相萃取-高效液相色谱(SPE-HPLC)方法。该方法经80%甲醇水提取样品,C18固相萃取小柱净化,采用DAD检测器220 nm紫外扫描检测。结果表明:3种植物生长调节剂在0.5¹0μg/mL内线性关系良好(r≥0.999);检出限分别为赤霉素0.002 mg/kg、多效唑0.04 mg/kg、烯效唑0.02 mg/kg;在0.210μg/mL内线性关系良好(r≥0.999);检出限分别为赤霉素0.002 mg/kg、多效唑0.04 mg/kg、烯效唑0.02 mg/kg;在0.2⁰.8 mg/kg加标水平下,3种植物生长调节剂平均回收率为78%0.8 mg/kg加标水平下,3种植物生长调节剂平均回收率为78%⁹1%;相对标准偏差为2.4%91%;相对标准偏差为2.4%⁵.4%。     

微波消解-电感耦合等离子体质谱法快速测定 方便面中的重金属

目的建立微波消解前处理-电感耦合等离子体质谱法(inductively coupled plasma-mass spectrometry,ICP-MS)快速检测方便面中铬(Cr)、砷(As)、镉(Cd)等重金属的含量。方法方便面样品经最佳微波消解程序处理后,采用ICP-MS测定Cr、As、Cd元素的含量;同时与GB 5009-2014进行对比验证方法的可行性,并对市售方便面中铬、砷、镉的含量进行检测。结果对空白样品进行1、5和10μg/kg 3个水平加标,平均回收率为96.1%~104.7%,相对标准偏差小于5.52%。Cr、As和Cd元素在0~50μg/kg浓度范围内线性关系良好,相关系数r均大于0.99。本方法测得不同品牌方便面铬浓度在34.78~131.67μg/kg之间,总砷的浓度在8.33~21.76μg/kg之间,镉的浓度在11.42~21.52μg/kg之间,均未超出国家标准限量。结论该方法快速准确,可适用于方便面中重金属含量的测定。     

超声辅助提取-HPLC-ICP/MS联用分析食品中水溶性铬价态

目的 建立一种超声辅助提取-高效液相色谱分离-电感耦合等离子体质谱仪联用法(HPLC-ICP/MS)测定食品中水溶性铬价态分析方法。方法 样品经EDTA-硝酸铵混合溶液提取后,含蛋白质的样品加入铁氰化钾和乙酸锌溶液沉淀蛋白质,0.45μm微孔滤膜过滤后备用。样品经离子交换柱分离,ICP/MS检测。结果 Cr(III)和Cr(VI)在0.5 ng/mL～50 ng/mL的范围内呈线性关系,大米和鸡蛋样品在0.025mg/kg,0.05mg/kg和2.0mg/kg添加水平下的回收率为62%~117.9%;土豆在0.025mg/kg,0.05mg/kg和1.0mg/kg添加水平下回收率为80.2%~118.2%;牛奶在0.025mg/kg,0.05mg/kg和0.6 mg/kg添加水平下回收率为64.5%~106.5%,日内相对标准偏差小于8%,日间相对标准偏差小于10%;两种价态的铬的检出限均为10 μg/kg。结论 该方法快速、准确、灵敏, 适合用于多种食品中可溶性铬价态分析检测。     

免疫调节性袋泡茶配方优化及功能性评价

目的：以绿茶、黄芪、党参、枸杞子、大枣为原料研制一款具有增强免疫力的功能性袋泡茶。方法：以感官评价为指标,应用正交试验结合模糊数学综合评定法优化袋泡茶配方,采用苯酚-硫酸法检测样品中总多糖含量。将SPF级昆明小鼠随机分为空白对照组、模型对照组、阳性对照组(1.40 mg/kg BW的蛋白粉)和袋泡茶低(0.52 g/kg BW)、中(1.04 g/kg BW)、高剂量组(1.56 g/kg BW),除空白对照组外,其余各组小鼠腹腔注射环磷酰胺制备免疫低下模型,连续给药21 d后测定小鼠体重和脏器指数;流式细胞术检测小鼠脾脏淋巴细胞CD3⁺细胞、CD4⁺细胞、CD8⁺细胞及CD4⁺CD8⁺细胞比例值;ELISA法测定小鼠血清中干扰素γ(interferon-γ,IFN-γ)含量。结果：袋泡茶的最佳配方为黄芪、党参、枸杞子、大枣、绿茶量分别为茶袋内容物总质量的13.00%、26.30%、20.50%、20.50%、19.70%,多糖含量为33.84±0.52 mg/g。药效实验结果...     

基于荧光法测定皮革中痕量Cr(Ⅵ)方法的研究

通过建立荧光猝灭法来检测皮革中痕量Cr(VI)的方法,为皮革中Cr(VI)的检测提供另一种选择。首先通过分析得到检测的最佳条件:测试温度为20℃;缓冲溶液pH为7.0,用量为2 mL;荧光素用量为1.0 mL;KI用量为2.0 mL;KI与Cr(VI)反应时间为15 min;静置时间为15 min。同时得到了测定Cr(VI)的回归方程为△F=6.0571C(μg/L)-5.2,线性相关系数r=0.9939,线性范围为4~60μg/L,检出限为8.4μg/L,精密度为2.01%,加标回收率大于91%。利用所建立的荧光猝灭法分析了6个不同Cr(VI)含量的皮革样品,并与紫外分光光度法对比,相对误差小于5%,说明该方法适用于皮革中Cr(VI)含量的测定。     

牛乳中铬形态研究与风险分析

首先建立了液相色谱法与液相色谱-电感耦合等离子质谱法测定牛乳中不同价态铬的方法。液相色谱法采用Ion Pac CG5A分析柱分离,PDC柱后衍生,紫外检测器测定不同价态铬质量浓度,当进样量为100μL时,对溶液中最低检出质量浓度[Cr(Ⅲ)]与Cr(Ⅵ)[Cr(Ⅵ)]分别为10.0μg/L与1.0μg/L;液相色谱-电感耦合等离子质谱法使用Ion Pac AG11阴离子交换色谱柱、NH4NO3淋洗液,可以很好地分离溶液中的Cr(Ⅲ)[Cr(Ⅲ)]和Cr(Ⅵ)[Cr(Ⅵ)],当进样量为100μL时,对溶液中最低检出质量浓度[Cr(Ⅲ)]与Cr(Ⅵ)[Cr(Ⅵ)]分别为0.25μg/L与0.03μg/L。通过在牛乳中添加不同浓度的Cr(Ⅵ)后测定Cr(Ⅲ)和Cr(Ⅵ),证明部分Cr(Ⅵ)可转化为Cr(Ⅲ)。通过分析认为因牛乳中存在一定量的还原物质而将Cr(Ⅵ)还原为Cr(Ⅲ)所致。当Cr(Ⅵ)添加量在0.8 mg/L以下时检测不出Cr(Ⅵ),说明当牛乳中铬的含量在国家规定的限量值(0.3 mg/L)以下时全部以Cr(Ⅲ)存在;即使铬质量浓度达到0.8 mg/L时,其对人体的危害风险仍较小(一定量的Cr(Ⅲ)对人体是有益的),都属于安全质量浓度范围。     

江苏沿海4种低值贝类软体中不饱和脂肪酸EPA和DHA动态积累规律与适宜采收期分析

采用GC/MS法对江苏沿海四种低值贝类软体中脂肪酸类成分进行定性分析,建立了HPLC法测定4种贝类软体中多烯不饱和脂肪酸二十碳五烯酸(简称EPA)和二十二碳六烯酸(简称DHA)的方法,在此基础上分析不同采收期4种贝类软体EPA和DHA的动态积累规律以评价这4种贝类软体的适宜采收期;同时以Waters Sun Fire C18柱(2.1 mm×100 mm,3.5μm)为色谱柱,乙腈(含0.1%磷酸)-水(含0.1%磷酸)(体积比74∶26)为流动相,流速0.6 m L/min等度洗脱,检测波长205 nm。该方法下,EPA-甲酯和DHA-甲酯分别在1.005 0⁸0.40μg/m L、1.106 280.40μg/m L、1.106 2⁸8.50μg/m L范围内呈良好的线性关系,灵敏度高,重现性好。不同的采收期,4种贝类软体中EPA和DHA的含量变化明显,在6.7月份时达到最高,菲律宾蛤仔、文蛤、青蛤和四角蛤蜊软体中EPA和DHA的总量分别为:771.5688.50μg/m L范围内呈良好的线性关系,灵敏度高,重现性好。不同的采收期,4种贝类软体中EPA和DHA的含量变化明显,在6.7月份时达到最高,菲律宾蛤仔、文蛤、青蛤和四角蛤蜊软体中EPA和DHA的总量分别为:771.56⁴ 565.38μg/g、263.114 565.38μg/g、263.11³ 115.78μg/g、5 907.833 115.78μg/g、5 907.83¹2 023.06μg/g和422.7112 023.06μg/g和422.71² 416.27μg/g。从产量和有效成分EPA和DHA的总量变化上综合考虑,建议菲律宾蛤仔、青蛤和四角蛤蜊最佳采收期在6月,而文蛤最佳采收期在7月。     

海产品中邻苯二甲酸酯的检测及健康风险评估

以海产品为分析对象,开发了16种邻苯二甲酸酯(PAEs)的GC-MS检测法。将方法应用于舟山经济海产品的检测,同时评估人体摄入海产品中PAEs的健康风险。结果显示,该方法线性范围、检出限(3S/N)分别为1～1 000μg/L和0.15～0.3μg/kg。低、中、高3个梯度加标回收率、相对标准偏差分别为73%～117%和2.8%～7.5%(n=5)。SPSS分析表明:不同海产品中PAEs浓度水平无显著性差异,∑PAEs含量为80.0～438μg/kg,其中邻苯二甲酸二-2-乙基己酯(DEHP)、邻苯二甲酸二丁酯(DBP)、邻苯二甲酸二异丁酯(DIBP)占比最高,占∑PAEs的83.01%～94.18%。健康风险评估表明,所测海产品中PAEs的健康风险在可接受范围,PAEs对成人的健康风险略低于儿童。     

Nanoparticles of chromium picolinate enhance chromium digestibility and absorption

BACKGROUND: Trivalent chromium (Cr) is a trace element that is difficult to digest and absorb. The objective of this study was to determine whether reducing organic Cr to nanometre size would increase its digestibility. RESULTS: Forty‐eight 8‐week‐old female Sprague‐Dawley rats were randomly assigned to one of four dietary treatments: (1) basal diet (control); (2) basal diet plus 300 µg kg^?1 Cr as chromium chloride (CrCl₃); (3) basal diet plus 300 µg kg^?1 Cr as chromium picolinate (Crpic); (4) basal diet plus 300 µg kg^?1 Cr as nanoparticulate Crpic (nanoCrpic). NanoCrpic was prepared from Crpic with a particle size of 55–100 nm. The experiment lasted 48 days. Cr digestibility and serum Cr concentration were 1.66 and 1.96 times greater respectively in rats fed nanoCrpic than in rats fed Crpic (P < 0.05). The average daily gain was greater in rats fed nanoCrpic or Crpic than in control rats (P < 0.05). The high‐density lipoprotein content increased while the very‐low‐density plus low‐density lipoprotein content decreased in rats fed nanoCrpic as compared with rats fed Crpic or CrCl₃ (P < 0.05). CONCLUSION: This study indicates that reducing the particle size of Crpic enhances Cr digestibility and absorption in rats and alters some blood metabolite concentrations. Copyright © 2009 Society of Chemical Industry     

三价铬镀铬阳极研究

比较六价铬离子和三价铬离子镀铬工艺的优缺点,综述近年三价铬镀铬工艺中石墨阳极、铅及铅基合金阳极以及DSA阳极的研究进展和应用情况,提出新型不溶性阳极的研究和使用是解决三价铬镀铬工艺中镀液的稳定性、阴极产品质量以及槽电压高等关键问题的有效手段之一,指出通过电沉积的方法制备多元复合电极材料和梯度功能复合电极材料将成为今后研究的主要方向之一。     

Effects of supplementing dairy cows with chromium propionate on milk and tissue chromium concentrations

Eight primiparous and 8 multiparous Holstein cows were used to determine the effects of Cr supplementation, in the form of Cr propionate (Cr Prop), on milk and tissue Cr concentrations. Cows were randomly assigned by parity to one of 2 diets: 1) control diet or 2) 2 mg of supplemental Cr/kg of DM. The level of Cr Prop supplemented exceeded by 4-fold the concentration of 0.5 mg of Cr/kg permitted by the FDA. Experimental diets were fed from approximately 30 d prepartum until at least 91 d postpartum, resulting in a minimum of 121 d of exposure to supplemental Cr. The control prepartum and postpartum diets analyzed 0.48 and 0.38 mg of Cr/kg of DM, respectively. Milk samples were obtained from the a.m. milking on d 0 (colostrum), 7, 14, 21, 28, 42, 56, 77, and 90 and on the final day of the study for Cr analysis. Cows were harvested after lactating for a minimum of 91 d and samples of liver, kidney, semitendinosus muscle, and fat were obtained for Cr analysis. Chromium was measured using electrothermal atomic absorption spectrophotometry. Milk Cr concentration averaged 1.7 ng/mL and was affected by day of lactation but not by Cr or a Cr × day interaction. Supplementation of 2 mg of Cr/kg of DM increased kidney Cr by approximately 3-fold and liver Cr concentrations by approximately 2-fold. Chromium concentrations in muscle and fat were not affected by Cr supplementation. In summary, supplementation of Cr Prop at a level of 2 mg of Cr/kg of DM did not affect Cr concentration in milk, muscle, or fat, the major bovine products consumed by humans.     

食品中总铬和铬形态分析的前处理技术概述

铬既是一种人体必需的微量元素,又是已确认的致癌物质之一,且铬的毒性与摄入的铬总量及形态有关。本文主要综述了近年来食品中总铬及铬形态分析的前处理技术的研究现状。总铬样品的前处理技术有微波消解、干灰化法、高压消解、湿法消解等。铬形态分析的难点在于Cr(Ⅲ)与Cr(Ⅵ)的存在价态会发生改变,因此前处理技术必须保证铬形态分析过程中的稳定性,这对于检测结果的准确性来说十分关键。本文详细分析了超声消解、加速溶剂萃取、浊点萃取、固相萃取等铬形态提取和富集技术,并其优缺点进行了讨论。同时,总结了食品中总铬及铬形态分析前处理方法存在的主要问题以及发展方向。     

废铬液循环过程中铬配合物组分变化特征的研究

采用离子交换-H2O-NaClO4-HCl梯度洗脱体系,对废铬液14次循环利用过程中的中性盐、铬配合物组分进行了跟踪测定。研究结果表明:整个循环过程中,中性盐由氯化钠型转化为硫酸钠型,并保持浓度稳定在0.82mol·L-1,铬配合物中阴/非离子型配合物组分稳定在3%～6%,带正电荷的配合物则由低价态逐渐向高价态转化,循环结束后,高价态配合物由51%增加到79%,配合物组成趋于稳定。     

Vitrification of chromium electroplating sludge

This work investigated the vitrification of hazardous electroplating sludge containing 140 mg/g Cr with/without bottom ash or cullet conditioning to lower specimens' basicities to 0.97-1.17 or 0.18-0.23, respectively. The conditioning was found to enhance the smooth/glassy appearance of slags but no ingot was obtained. Cr was >98% retained in the vitrified slags. Cr2O3 dominated in crystalline structure for the slag vitrified from the sludge, but this domination gradually shifted to Fe2SiO4/Fe3O4/SiO2 or SiO2 crystalline with increasing addition of bottom ash or cullet into the sludge, respectively. Compared to the raw sludge, the sludge-vitrified slag displayed lower leaching concentrations for most metals (particularly Cr (2.54 mg/L)), and smaller leaching ratios for Ag, Cr, and Cu (1.35, 0.02, and <0.01%, respectively) but greater ones for Cd, Pb, and Zn (3.83, 2.46, and 0.36%, respectively). The Cr leaching ratios were approximately 0.01% for the slags vitrified from the conditioned sludge. Independent of the slag basicity and crystalline structure, metal leaching quantity increased but leaching ratio decreased with increasing slag metal content. The slag compressive strengths were improved to >14.7 MPa at the mixing ratios > or = 2/1 and 1/1 for bottom ash/sludge and cullet/sludge, respectively. Fulfilling the criteria of Toxicity Characteristic Leaching Procedure (TCLP), all the slags were recyclable.     

The contemporary anthropogenic chromium cycle

Chromium is an essential engineering metal used in stainless and alloy steels, chemicals, and refractory products. Using material flow analysis, all major anthropogenic chromium flows are characterized for the year 2000, from mining through discard, on three spatial levels: fifty-four countries, nine world regions, and the planet. Included is the first detailed quantification of chromium in internationally traded finished products and diverse waste streams. Findings include (1) 78% of chromium flow entering final use is added as a net addition to stock on the global level; most countries are close to this figure; (2) the majority of mining occurs in Africa (2400 Gg Cr/yr) and the Commonwealth of Independent States (1090 Gg Cr/yr), while the major end-users are Asia, Europe, and North America at 1150, 1140, and 751 Gg Cr/yr, respectively; (3) waste flows of chromium are the greatest in Europe (420 Gg Cr/yr), Asia (370 Gg Cr/yr), and North America (290 Gg Cr/yr), but the composition of these waste flows varies greatly among the world regions; (4) releases of chromium by the global system, which total 2630 Gg Cr/yr, are nearly evenly divided among tailings, ferrochromium slag, downgraded scrap, and post-consumer losses; (5) many countries have a heavy foreign dependence on chromium in the all forms, as is demonstrated for the United States. The findings relating to in-use stock changes and finished product trade are relevant to industry, allowing for more accurate planning for future scrap availability. The quantification of releases due to discards and dissipation hold environmental and human health relevance, while the full life cycle international trade assessment addresses local scarcity.     

Efficacy of trivalent chromium on growth performance,carcass characteristics and tissue chromium in heat‐stressed broiler chicks

BACKGROUND: Trivalent chromium (Cr) is usually claimed to have a positive effect on growth and carcass traits in livestock. The objective of this study was to comparatively assess the effects of 6 weeks of treatment with different forms of Cr (500 µg kg^?1), namely Cr nanocomposite (CrNano), Cr picolinate (CrPic) and Cr chloride (CrCl₃), on growth performance, carcass characteristics and tissue Cr in heat‐stressed broiler chicks. RESULTS: Supplementation of CrNano and CrPic significantly increased average daily gain, feed efficiency, carcass yields and lean muscles and decreased abdominal fat. In addition, CrNano significantly increased protein contents in breast and thigh muscles and lowered fat and cholesterol levels in thigh muscles. CrPic significantly increased thigh muscle protein content and decreased thigh muscle fat and cholesterol levels. Dietary addition of CrNano, CrPic and CrCl₃ resulted in significant increases of Cr content in serum, liver and kidney. Moreover, supplemental CrNano produced significant increments of Cr deposit in breast and thigh muscles. CONCLUSION: The results indicate that supplementation of Cr in the form of CrNano and CrPic might be an effective tool for enhancing the growth performance and carcass traits of broiler chicks in heat‐stressed condition. CrNano seemed to have greater beneficial effects in comparison with CrPic. Copyright © 2009 Society of Chemical Industry     

Heat-treated wood as chromium adsorption material

Heavy metals adsorption with lignocellulosic materials has been heavily researched in the last years. Since heat activation has been used with good results to increase the adsorption capacity of some materials, heat-treated wood might be a better adsorbent. This hypothesis is the basis of the present study. The adsorption tests were made with powdered pine wood, heat-treated at 190–210?°C. All the heat-treated samples showed a significantly higher adsorption compared to untreated wood. The maximum adsorption was obtained at pH 3 for heat-treated wood at 210?°C. The kinetics of the adsorption process fitted a pseudo-second-order reaction (R² 0.990–0.996). Adsorption fitted well both the Langmuir and the Freundlich model, but the Freundlich model presented higher R² (0.988–0.998). The q_max values estimated by the Langmuir plotting were in the range 15.6–19.4 mg/g and the n values from Freundlich isotherms between 1.87 and 2.39. Heat-treated wood was a better adsorption material than untreated wood for chromium adsorption. This can be a good application for the sawdust produced by the processing of heat-treated wood at primary and secondary wood processing mills or for the recycling of heat-treated wood at the end of product life.