微波消解-原子荧光法测定食品中总砷

目的建立应用微波消解-原子荧光法快速、准确地测定食品中总砷的方法。方法采用微波消解法对食品样品进行前处理,氢化物发生原子荧光法测定食品样品中总砷。结果砷的质量浓度在0~10μg/L范围内与原子荧光强度呈良好的线性关系,相关系数为0.999 4,方法检出限为0.006 mg/kg,回收率为96.1%~104.9%。结论本方法能简便、准确地测定食品中总砷。     

微波消解-氢化物发生-原子荧光光谱法测定海产品中痕量汞

目的:建立海产品中痕量汞的微波消解-氢化物发生-原子荧光光谱测定方法。方法:采用微波消解法对样品进行前处理,以硼氢化钾为还原剂,5%盐酸为载流,氩气为载气,利用原子荧光法对样品中的痕量汞进行测定。结果:汞在0.1μg/L～10.0μg/L范围具有良好的线性,相关系数大于0.9990,RSD在1.7%～8.8%之间。采用本法对紫菜成分分析标准物质(GBW10023)和黄鱼成分分析标准物质(GBW08573)进行了方法验证,所测结果均在标准参考值允许范围之内。结论:本法具有简便、灵敏、准确的优点,适合海产品中痕量汞的测定。     

测定尿中砷的微机消解-原子荧光光谱法

目的为开展正常人群尿砷水平调查和职业接触人群的接触水平调查建立快速、准确的检验方法。方法尿样经微机消解仪批量消解,原子荧光光谱法测定尿中砷。结果溶液浓度在0—40μg/L范围内标准曲线线性良好,r=0．9991,样品RSD％为2．26％-2．99％,样品的加标回收率为95．65％-102．5％,方法的检出限为0．046μg/L。结论采用常用设备微机消解仪一次能消解60份样品,样品前处理简单快捷,且具有较好的准确度、灵敏度,适合大批样品的普查检验。     

原子荧光光谱法测定酱油中的砷

目的:建立新的试样处理方法测定酱油中砷。方法:原子荧光光谱法测定。结果:简化前处理方法,检出限为0.038μg/L,标准曲线相关系数为0.9996,相对标准偏差为1.59%,平均回收率为96.3%~98.5%。结论:该法准确度、精密度良好、灵敏度高,是简便、快速、实用的测定酱油中砷的方法。     

血液和尿液中砷的原子荧光光度测定法

目的探讨血液和尿液中砷的最佳测定方法。方法采用微波消解氢化物发生原子荧光光度法测定血液和尿液中的砷。结果在最佳条件下砷的最低检出限为0.076 8μg/L,砷回收率为89.0%～103.7%,RSD为2.4～5.1%。结论该方法具有简便,快速,灵敏度高,干扰少,线性范围宽等优点。     

微波消解-原子荧光光谱法测定酱油中总砷

目的:建立测定酱油中总砷的氢化物发生-原子荧光法.方法:以硝酸为消化剂进行微波消解后,原子荧光法测定.结果:线性范围为0～50 μg/L.方法检出限为0.016 mg/L,加标回收率为97.2%～101.1%,RSD为2.42%～4.28%.结论:方法简单、快速、结果准确可靠,适用于批量检测,适合酱油中总砷含量的检测分析.     

液相色谱-原子荧光联用测定作业场所空气中的无机砷

目的 建立液相色谱-原子荧光光谱法测量作业场所空气中亚砷酸盐As(Ⅲ)与砷酸盐As(V)含量的方法.方法 样品经0.15 mol/L硝酸90 ℃浸提1h后,以15 mmol/L磷酸氢二铵为流动相,CNWSep AX(250 mm × 4.0 mm× 10 μm)(LAEQ-4025G7)色谱柱分离,分析检测空气样品中A...     

氢化物发生原子荧光法测定硅藻土中砷

目的:为了建立硅藻土中砷的原子荧光光谱测定方法。方法:样品经处理,使用硫脲-抗坏血酸-碘化钾混合溶液作为预还原剂,研究了硅藻土中砷的原子荧光光谱测定方法的最佳测定条件。结果:本法选择20 g/L KBH4溶液作为还原剂,50 g/L硫脲-50 g/L抗坏血酸-50 g/L碘化钾混合溶液作为预还原剂,线性范围为0~10μg/L,相关系数r≥0.9999,检出限为0.026μg/L,加标回收率为92.3%~109.3%%,相对标准偏差为3.67%。结论:该方法简便快速、灵敏度高、准确度好,适合硅藻土中砷的测定。     

大米中无机砷测定方法的研究

目的通过比较不同浓度三氟乙酸(TFA)溶液和在不同提取时间下TFA对于标准参考物质(SRM1568a rice flour)中无机砷化合物的提取能力,优化TFA溶液的浓度和提取时间,提出大米中无机砷测定方法。同时采集不同原产地的大米样品,评价无机砷污染状况。方法加入TFA,热浸提后取上清液离心浓缩至干,以流动相超声复溶,过RP柱和滤膜后进样;1mmol/L磷酸二氢铵溶液(pH9.0)和20mmol/L磷酸二氢铵溶液(pH8.0)为流动相梯度洗脱,采用Hamilton PRPX-100阴离子交换柱分离,液相色谱-原子荧光光谱法(LC-AFS)测定。结果采用3%(V/V)TFA溶液对SRM1568a热浸提2h的样品前处理方法,其测定结果符合无机砷参考值。结论方法适用于大米中无机砷的测定。所采集大米样品的无机砷含量均未超出卫生标准。     

Occurrence and role of umami molecules in foods

Glutamate is a multifunctional amino acid. It plays a key role in central neurotransmission, in intermediate metabolism of carbohydrate as well as in taste, representing the major ligand having the umami taste. Glutamate is one of the main constituents of dietary proteins and is also consumed in many prepared foods as a flavour enhancer in the form of glutamate salts. Umami perception is based on multiple receptor systems distributed in the oral cavity and in the gastrointestinal tract which activates a number of regions of the brain involved in different functions, from food identification to the formation of an affective value related to a particular food, which may influence appetitive behaviour. Future research on umami taste and umami compounds will be fundamental in gaining a better understanding of their physiological significance and to promote their status in a healthy and pleasant diet.     

Occurrence and role of umami molecules in foods

Glutamate is a multifunctional amino acid. It plays a key role in central neurotransmission, in intermediate metabolism of carbohydrate as well as in taste, representing the major ligand having the umami taste. Glutamate is one of the main constituents of dietary proteins and is also consumed in many prepared foods as a flavour enhancer in the form of glutamate salts. Umami perception is based on multiple receptor systems distributed in the oral cavity and in the gastrointestinal tract which activates a number of regions of the brain involved in different functions, from food identification to the formation of an affective value related to a particular food, which may influence appetitive behaviour. Future research on umami taste and umami compounds will be fundamental in gaining a better understanding of their physiological significance and to promote their status in a healthy and pleasant diet.     

The occurrence of Bacillus cereus in fast foods

The rate and the level of contamination by Bacillus cereus in various fast foods were investigated. The strains isolated were differentiated by DNA digestion with restriction enzymes and pulsed-field gel electrophoresis (PFGE). A total of 90 single servings of foods were purchased in 16 restaurants, cafeterias and buffets in Naples (Italy). Ten samples (11.1%) resulted in contamination by B. cereus. The contamination levels ranged from 10³ to 10⁵ cfu g^-1. The most contaminated foods were the fish dishes (21.4%), with counts ranging between 10⁴ and 10⁵ cfu g^-1. Such rate of contamination is noticeably lower than those reported in other countries. The genomic typing obtained by the PFGE of the restriction digests showed the existence of a high polymorphism also in the B. cereus strains isolated from different ready-to-eat foods purchased together in the same restaurant.     

Comparison of different medical cases in urinary arsenic speciation by fast HPLC-ICP-MS

The inorganic arsenic species As(III), As(V) and the organic species methylarsonate (MMA(V)), dimethylarsinate (DMA(V)) and arsenobetaine (AsB) were determined in human urine by a fast anion exchange HPLC-ICP-MS method, which was developed for clinical laboratories with high sample throughput. This paper compares typical chromatograms of the arsenic species in urine samples collected in different medical cases, for example, for the non-exposed population, for environmentally (plant protectants) and occupationally (glass manufacture) exposed persons, for a person after a failed suicide attempt with As2O3 and for persons before and after administration of the antidot sodium 2,3-dimercapto-1-propane-sulfonate (DMPS). Concentration data of the urinary As species for the non-exposed German population (n=82) are compared with the concentrations before and after administration of DMPS (n=37). For the non-exposed group the toxicologically relevant As in urine consists of 81% DMA(V), 10% MMA(V) and 9% inorganic As. However, a few hours after an acute intoxication with inorganic As this distribution changes dramatically and As(III) and As(V) are predominantly found in urine. After treatment with DMPS the total As concentration increases significantly and mainly MMA(V) and As(III) were found in urine samples.     

卷烟滤嘴中砷的高压消解-氢化物-原子荧光光度测定法

目的建立卷烟滤嘴中砷的高压消解-氢化物-原子荧光光度测定方法。方法卷烟滤嘴经高压消解及优化实验条件后,用原子荧光光度法测定其中的砷含量。结果实验表明,方法在0～20μg/L浓度范围内线性相关系数为0.9997,检出限为0.021 1μg/L,加标回收率在86.6%～103.4%之间,方法精密度(RSD)小于5%。结论该法具有简便、灵敏、准确等特点,适合于卷烟滤嘴中砷含量的测定。     

氢化物发生-原子荧光光度法测定铝制食具容器中砷溶出量

目的:建立铝制食具容器中砷溶出量的氢化物发生-原子荧光光度测定方法。方法:铝制食具容器用4%乙酸溶液浸泡,浸泡液用原子荧光光度法测定,测定条件:负高压260 V;灯电流60 mA;原子化器温度200℃,原子化器高度8 mm;载气流量400 ml/min;屏蔽气流量1000 ml/min。结果:实验表明,方法在0 ng/ml～10 ng/ml浓度范围内线性相关系数为0.999,检出限9.6×10-5mg/L,加标回收率在89.0%～103.3%之间,方法精密度(RSD)小于4.0%。结论:该法具有简便快速、灵敏、准确等特点,适合于铝制食具容器中砷溶出量的测定。     

Gadolinium concentration analysis in brain phantom by X-ray fluorescence

We have measured the X-ray fluorescence from gadolinium as a function of concentration and position in tumors of different sizes and shapes in a head phantom. The gadolinium fluorescence was excited with a 36 GBq Am-241 source. The fluorescence signal was detected with a CdTe detector and a multi-channel analyzer. The fluorescence peak was clearly separated from the scattered X-rays. Concentrations of 5.62–78.63 mg/ml of Gd ion were used in 1, 2, and 3 cm diameter spherical tumors and a 2 × 4 cm oblate spheroid tumor. The data show trends approaching saturation for the highest concentrations, probably due to reabsorption in the tumor. A comparison of X-ray photographic imaging and densitometer measurements to determine concentration is also presented.     

食品添加剂中砷的测定方法研究

目的:研究氧化物发生原子荧光法用于食品添加剂中的痕量砷的测定.方法:本文通过试验确定十余种无机和有机食品添加剂样品砷测定的预处理方法,找到较为简单、排除各种干扰的样品前处理方法,根据试验原理.通过查阅资料及实验的方法确定用丁测定砷时的反应体系及最佳仪器条件.采用加标回收法,在最件反应条件下,再次验证方法的准确度和精密度,并计算方法的最低检出限.结果:实验结果表明,在最佳条件下,该法的回收率为88.1%～108.8%之间,相对标准偏差(RSD)为0.48%～2.57%.方法的检出限为0.51 ng/ml.结论:该方法是一种操作简便、准确、快速、便于普及推广的方法,适用于基层实验室.     

氢化物原子荧光法测定茶叶中的硒和砷

目的:建立双道原子荧光法同时测定茶叶中的砷和硒的方法。方法:样品经硝酸-高氯酸消解后,采用AFS-9130原子荧光光度计对其中的砷和硒含量进行分析。结果:在最佳实验条件下,砷、硒的相对标准偏差分别是砷为<5.58%,硒相对标准偏差<5.92%,检出限分别为砷0.0020 mg/kg,硒为0.0038 mg/kg,回收率分别为91.0%~99.1%和95.0%~98.3%。结论:方法精密度高,结果准确可靠,适用于茶叶中砷、硒的同时测定。     

离子色谱-氢化物发生原子荧光法测定尿中形态砷

目的:建立离子色谱-氢化物发生原子荧光法测定尿中形态砷的方法。方法:尿样经0.45μm滤膜过滤,以(NH4)2HPO4为流动相,采用离子色谱-氢化物发生原子荧光联机测定不同形态砷的含量。结果:实验结果相关性好,线性范围宽,精密度RSD为2.60%～4.30%,方法检出限为As(Ⅲ)2.0μg/L,DMA4.0μg/L,MMA4.0μg/L,As(Ⅴ)8.0μg/L,该方法所得回收率为90.48%～102.90%。结论:方法简便、快速、无需化学预处理、干扰少、灵敏度高,有较高的实用价值。