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阻抑褪色光度法测定痕量汞 总被引:8,自引:0,他引:8
提出一种测定痕量汞的新的光度法。该法基于Hg(Ⅱ)对H2O2与离子缔合物AgCl·PVA·Ag~+·Fin~-褪色反应的抑制效应,该离子缔合物对应于聚乙烯醇存在下Fajans(法扬斯)法的终点,线性回归方程△A=0.02+ 4.0×10~(-3)C_(Hg(Ⅲ))(μg/L),相关系数r=0.9992,Hg(Ⅱ)浓度在4.0~20.0μg/L范围内服从比耳定律,检出限0.04μg/L。该法用于废水样中Hg(Ⅱ)的测定,结果与双硫腙法结果相符。 相似文献
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阻抑动力学光度法测定痕量对苯二酚 总被引:13,自引:0,他引:13
基于在硫酸和聚乙烯醇溶液中,对苯二酚能抑制Fe(Ⅲ)催化中性红与H2O2之间的褪色反应,建立了一种测定痕量对苯二酚的新方法,同时研究了该方法的动力学条件。该方法的测定范围为0.20~6.0mg/L;检出限为2.3×10-4g/L;ε535=1.2×104L·moL-1·cm-1。用于废水中对苯二酚的测定,结果满意。 相似文献
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催化动力学光度法测定痕量锆(Ⅳ) 总被引:25,自引:0,他引:25
研究了在稀盐酸介质中,α,α’-联吡啶存在下,锆催化溴酸钾氧化考马斯亮蓝G使其褪色这一新的指示反应及其动力学条件,建立了灵敏地测定痕量锆的新方法。该方法检出限为8.98×10^-11g/mL,线性范围0-10.4μg/L,用于合金钢中痕量锆的测定,结果满意. 相似文献
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偶氮胂Ⅲ光度法测定江水中痕量铬 总被引:5,自引:0,他引:5
1引言废水中铬(Ⅵ)的外排直接威胁着人们的身体健康,对其监测是非常必要的。目前褪色法测定铬(Ⅵ)有:偶氮氮膦类显色剂(ε=2-3×104L·mol-1·cm-1);二溴羧基偶氮胂(ε=2×105L·mol-1·cm-1);本文观察到在硝酸介质中偶氮胂Ⅲ与具有高灵敏褪色反应,ε=1.9×106L·mol-1·cm-1。此法操作简便,灵敏度高,条件易于控制。此法用于测定江水中痕量铬(Ⅵ),获得了满意的结果。2实验部分2.1主要试剂和仪器1.0000glLC4[标准溶液,用时再配成0.SIng/L的工作溶液ZO.sg/L的偶氛肿ill溶液。722型分光光度计(上海第三… 相似文献
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在盐酸溶液中,钛(Ⅳ)与钽试剂(BPHA)络合物在-0.3V(vs.SCE)或开路情况下吸附于玻璃碳电极表面,在-0.3--0.8V范围内以250mV.s^-1进行扫描溶出,峰电位为-0.57V,钛(Ⅳ)浓度在1-35ng.ml^-1(-0.3V)下富集2min和0.06-2ng.ml^-1(开路富集4min)范围内与峰电流呈良好的线性关系,体系选择好,灵敏度高,操作简单,用于纯铝中痕量钛的测定,重现性好,结果准确。 相似文献
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X射线荧光光谱法测定水样中的痕量元素 总被引:2,自引:0,他引:2
采用波长色散X射线荧光光谱仪测定了水样中痕量的A1、Cr、Ni、Zn、Sr、Ba、Tl、Pb。本法的测量结果与ICP和AAS的结果相近,对5.7μg/g Sr测量5次的RSD为1.2%,Sr的检出限(LLD)达到0.1μg/g。 相似文献
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石煤渣中痕量铌的高灵敏光度法测定 总被引:1,自引:0,他引:1
1引言利用Nb(Ⅴ)-SCN-RhB-PVA高灵敏显色体系。在聚乙烯酸(PVA)存在下,铌(Ⅴ)与疏氰酸盐形成配阴离子再和罗丹明B(RhB)形成较稳定的离子缔合物,可用光度祛在水相中直接测定铌(Ⅴ)。通过试验,确立了体系反应的最佳条件,在PVA介质中,离子缔合物的λmax=565nm,ε=7.9×105·mol-1·cm-1,铌(Ⅴ)量在0-0.2mg/L范围内服从比耳定律。本法用于测定石煤渣中痕量铌,获得了满意结果。2实验部分2.1仪器和试剂721型分光光度计(上海第三分析仪器厂);pffe3型酸度计(上海第二分析仪器厂);501型超级恒温器(上海实… 相似文献
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Food ingredient adulteration, especially the adulteration of milk and dairy products, is one of the important issues of food safety. The large price difference between camel milk powder, ovine, and bovine milk powder may be an incentive for the incorporation of ovine and bovine derived foods in camel milk products. This study evaluated the use of ordinary PCR and real-time PCR for the detection of camel milk powder adulteration based on the presence of ovine and bovine milk components. DNA was extracted from camel, ovine, and bovine milk powder using a deep-processed product column DNA extraction kit. The quality of the extracted DNA was detected by amplifying the target sequence from the mitochondrial Cytb gene, and the extracted DNA was used for the identification of milk powder based on PCR analysis. In addition, PCR-based methods (both ordinary PCR and real-time PCR) were used to detect laboratory adulteration models of milk powder using primers targeting mitochondrial genes. The results show that the ordinary PCR method had better sensitivity and could qualitatively detect ovine and bovine milk components in the range of 1% to 100% in camel milk powder. The commercial camel milk powder was used to verify the practicability of this method. The real-time PCR normalization system has a good exponential correlation (R2 = 0.9822 and 0.9923) between ovine or bovine content and Ct ratio (specific/internal reference gene) and allows for the quantitative determination of ovine or bovine milk contents in adulterated camel milk powder samples. Accuracy was effectively validated using simulated adulterated samples, with recoveries ranging from 80% to 110% with a coefficient of variation of less than 7%, exhibiting sufficient parameters of trueness. The ordinary PCR qualitative detection and real-time PCR quantitative detection method established in this study proved to be a specific, sensitive, and effective technology, which is expected to be used for market detection. 相似文献
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亲水色谱-串联质谱法对牛奶与奶粉中三聚氰胺及其衍生物含量的测定 总被引:2,自引:0,他引:2
建立了牛奶和奶粉中三聚氰胺及其3种衍生物(三聚氰酸、三聚氰酸一酰胺、三聚氰酸二酰胺)的亲水色谱-串联质谱检测方法(HILIC-MS/MS)。牛奶样品直接用乙腈超声波提取;奶粉样品先用水溶解后再加乙腈超声波提取,高速离心后以乙腈-水为流动相,采用亲水作用色谱柱分离这4种化合物,在电喷雾正、负电离切换多反应监测模式下进行定性与定量分析,三聚氰酸一酰胺与三聚氰酸二酰胺含量在50~10000μg/kg之间、三聚氰胺与三聚氰酸在25~5000μg/kg之间,均获得良好的线性。方法检出限(LOD)为5~20μg/kg,定量下限(LOQ)为50~100μg/kg,3个添加水平的平均回收率为81%~97%。该方法简便、快速、准确,可满足牛奶及奶粉中三聚氰胺、三聚氰酸、三聚氰酸一酰胺、三聚氰酸二酰胺测定的需要。 相似文献
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王梅 《分析测试技术与仪器》2016,(3):165-168
利用甲醇沉淀进口奶粉、国产奶粉和奶茶粉水溶液中的蛋白质,所得上清液用二氯甲烷萃取,再经傅里叶变换红外光谱法(FT-IR)分析沉淀物和各相中物质的成分.试验结果表明:3种样品沉淀物中均含有蛋白质和脂肪酸甘油三酯,在萃取时均有乳糖析出.三者上层(水+甲醇)均含有糊精;而下层(二氯甲烷-甲醇)进口奶粉中含有磷脂酰胆碱,国产奶粉中含有磷脂酰胆碱和长碳链伯酰胺,奶茶粉中含有咖啡因. 相似文献
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Certain aldehyde and ketone compounds can be used as indicators, at a molecular level, of the oxidized flavor of milk powder instead of sensory evaluation. This study investigated the formation of aldehyde and ketone compounds as affected by the heat-related processing and storage of milk powder. The compounds were extracted by solid phase microextraction fiber and determined using gas chromatography-mass spectrometry. In the results, higher contents of hexanal, 2-heptanone, octanal and 3-octen-2-one were detected in concentrated milk and fresh milk powders than in raw milk and heated milk. The levels of these compounds increased with increasing time of storage of milk powder. Meanwhile, the DPPH radical scavenging activity decreased and peroxide value increased during the production and storage of milk powder. In addition, the pore volume distribution of milk powder particle was determined by nitrogen isotherm adsorption. The porosity of milk powder was significantly correlated to the changes of aldehyde and ketone compounds during storages periods of 3 months (r > 0.689, p < 0.05) and 6 months (r > 0.806, p < 0.01). Therefore attention should be paid to the detectable aldehyde and ketone molecules to control the oxidized flavor, which was influenced by pre-heating as well as concentration and drying during milk powder production. 相似文献
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MU Zhi-Chun 《高等学校化学学报》1999,20(Z1):495
In the inspection of diary products, it is frequently required to distinguish between whey powder and milk powder,but there is no standard test method for this work now. According to Nation Standards,the concentration of fat could be used as a criterion for distinguishing between whey powder and milk powder. Meanwhile, the method of fat analysis is sophistic and not suitable to be used as a quick analysis. In order to overcome this problem, a rapid test method in following have be developed. 相似文献
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本文建立了奶粉中同时检测三聚氰胺及二聚氰胺的表面增强拉曼光谱法.奶粉样品经15%三氯乙酸溶液提取,中性氧化铝吸附杂质后进行拉曼光谱检测.三聚氰胺线性范围为0.0050~0.075 mg/L,检出限为0.0015 mg/L,回收率在79.5%~124%之间,相对标准偏差小于8.8%(n=5);二聚氰胺线性范围为0.50~l0mg/L,检出限为0.15 mg/L,回收率在76.5%~112%之间,相对标准偏差小于9.4%(n=5).该方法相比常规表面增强拉曼光谱法,仅通过一种样品前处理手段即可对奶粉中的三聚氰胺或二聚氰胺进行定性检出及定量分析,相比色谱等检测方法具有样品前处理过程简单、耗时短等优点,在奶粉质量监控方面具有良好的应用前景. 相似文献
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乳粉真伪问题是我国食品安全的突出问题之一,其非定向筛查是分析科学领域的前沿热点。该研究提出一种稳健建模驱动的拉曼高光谱成像方法(RMD-RHIM),借助其图谱合一的数据特征,将乳粉中未知掺杂物识别问题转化为奇异样本识别问题,有效解决了乳粉中掺杂物的不确定性问题。在RMD-RHIM中,首先采用自适应迭代重加权惩罚最小二乘算法(airPLS)扣除拉曼光谱的背景信息,再通过改进迭代自权重偏最小二乘法(mIRPLS)准确识别乳粉拉曼高光谱成像信号中的畸变像素点,并转化为可视化的二值图像,实现了乳粉真伪的非定向筛查。结果表明,RMD-RHIM方法对阳性和阴性样品的识别率分别达到了98.3%和93.3%,可满足乳粉工业快速筛查的需求,并为其它食品样本的非定向筛查提供了一种新手段。 相似文献
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超高效液相色谱-串联质谱法测定牛奶和奶粉中6种聚醚类抗生素残留量 总被引:5,自引:0,他引:5
建立了用于检测牛奶和奶粉中拉沙洛菌素、莫能菌素、尼日利亚菌素、盐霉素、甲基盐霉素和马杜霉素铵6种聚醚类抗生素残留量的超高效液相色谱-串联质谱分析方法.用乙腈提取样品中的聚醚类抗生素,提取液经HLB固相萃取柱净化,采用超高效液相色谱分离,以电喷雾离子源正离子多反应监测模式进行质谱分析.6种抗生素在0.5~100.0 μg/L范围内均呈线性,相关系数r>0.99.在空白样品中添加6种聚醚类抗生素的回收率均在74.0%~98.5%之间; 精密度(RSD)4.8%~17.2%.牛奶中6种聚醚类抗生素检出限均为0.2 μg/L;奶粉中6种聚醚类抗生素检出限均为1.6 μg/kg. 相似文献