火焰和石墨炉原子吸收光谱法对大米中金属元素含量的测定分析

采用火焰和石墨炉原子吸收光谱法对随机抽取的江西省、吉林省共五种大米中的Fe、Cu、Zn、Mn、Ca、Pb等六种金属元素进行了测定。结果表明,江西省大米中的金属元素含量均略高于吉林省前谷县达里巴乡大米,这可能与南北土壤中金属元素的分布不同有关。     

基于GC-TOF/MS技术的转Bt基因大米代谢组学研究

基于GC-TOF/MS技术对来源于两个不同产地的转Bt基因及其亲本大米进行了代谢组学研究。从大米样本中共检出774个色谱峰,鉴定出278种代谢产物,包括糖、氨基酸、脂肪酸及有机酸等代谢产物。对转Bt基因及其亲本大米进行主成分分析,结果表明,转Bt基因与亲本大米的代谢组之间无明显差异性,进一步对数据进行偏最小二乘判别分析和方差分析,仅甘油和鼠李糖两种代谢产物浓度在转Bt基因大米及其亲本大米间存在一定差异(分别升高1.55和3.32倍);考察了不同产地对大米代谢组的影响,结果表明武汉和海南两个产地的大米代谢组之间存在明显差异,有15种代谢产物在不同产地的亲本大米之间以及不同产地的转基因大米之间均发生显著变化。应用GC-TOF/MS技术对来源于不同产地的转Bt基因大米及其亲本大米的代谢组进行比较研究,结果表明引入外源Bt基因对实验中的水稻机体内代谢未产生明显影响,产地差异造成的大米间代谢组差异比引入外源Bt基因造成的大米间代谢组差异更为显著。     

分光光度法测定桂西大米中铁的含量

用分光光度法直接测定了大米中铁的含量，方法简便快速准确，对指导人们合理食用大米进行补铁及进一步开发大米产品提供了可靠的理论依据。     

气相色谱结合化学计量学区分大米贮藏时间与产地

香气是衡量大米质量的一个主要因素,对大米的食用品质有重要影响。该文以顶空固相微萃取(SPME)技术为基础,采用气相色谱法分别分析了不同贮藏时间和不同产地大米样本的挥发性成分,通过主成分分析法(PCA)和偏最小二乘判别分析法(PLS-DA)对大米样本进行分类和判别分析。PCA及PLS投影图显示不同储藏时间的大米明显聚为4类,通过留一交叉验证法(LOO)计算PLS预报的准确率为96%,相对标准误差为8.2%。同时,PCA投影图中可将4个不同产地的大米样本进行区分,分类效果显著;所建PLSDA模型可靠,不同产地大米样本均能被准确识别,正确率为100%。以顶空固相微萃取/气相色谱检测大米中挥发性成分,利用主成分分析法和偏最小二乘判别分析法鉴别大米新鲜程度和产地具有可行性。     

GC - MS法对不同产地大米的快速鉴定

采用GC - MS对4种不同产地大米中的脂溶性成分进行分析,并利用NIST标准质谱库和质谱图搜索程序进行检索.结果表明,大米中主要的脂溶性成分为棕榈酸、亚油酸、油酸、角鲨烯和谷甾醇.不同产地大米中脂溶性化合物的指纹谱图存在显著差异,通过主成分分析和聚类分析,建立了一种对不同产地大米进行快速鉴定的方法.     

基于气相色谱-质谱的拟靶向代谢组学方法分析大米中脂肪酸

建立了一种基于气相色谱-质谱的拟靶向代谢组学分析方法对大米中脂肪酸进行分析,共检测到16种脂肪酸,并研究了不同大米中脂肪酸的轮廓差异。以提取到饱和脂肪酸和不饱和脂肪酸的总量为评价指标,比较了6种提取方法及4种提取溶剂对脂肪酸提取效率的影响。将该方法用于5种不同大米（稻花香、吉星、金浪子、农大、状元）中脂肪酸的分析,发现稻花香大米中脂肪酸轮廓与其他4种均有较大差异;而金浪子与农大、状元间脂肪酸差异也较大,与吉星脂肪酸轮廓较为相似。该方法简单,有较好的稳定性和准确性,可为大米品质和营养价值改善研究提供基础数据。     

大米中镉检测能力验证

镉是剧毒物质,常通过土壤或水被农作物(特别是水稻等)吸收。世界各国对大米中镉含量均有严格限制,我国粮食卫生标准GB 2715—2005中镉的限量为0,2 mg·kg~(-1)。近年来,国家大米监督抽查结果显示,我国南方部分省份的大米镉含量超标,据调查环境污染是造成大米中镉超标的主要原因。本工作通过对2008年国家认监委能力验证计划《大米     

辽宁盘锦大米挥发性成分的GC-MS分析

位于渤海之滨、辽河三角洲的盘锦市,是我国著名的优质稻米生产基地.其产品不仅销往国内各地,而且打入国际市场.盘锦大米不仅粒形完整、洁白透明有光泽,而且香味浓郁、柔软适口,深受人们喜爱.盘锦大米之所以如此受欢迎,与它的香味有直接关系.早在1980年美国化学家Bttery和Ling证明了亚洲大米有爆玉米花香味物质,1989年美国又一名化学家证明了香米的芳香性,1996年英国化学家Widijajak Jcraske用水蒸气蒸馏方法比较系统地进行了香米和非香米挥发性组分的比较研究[1].而对于国内生产的大米的香味成分还很少有人分析.本文首次利用索氏提取法提取盘锦大米的挥发性成分,通过GC-MS联用技术分析确定了其中45种成分,其中含量较高的是十六烷酸(8.05%)、邻苯二甲酸(4.49%)、9-十八碳烯酸(2.99%)、9,12-十八碳二烯酸(2.19%)、十六酸甲酯(1.52%),希望对进一步研究盘锦大米的香味构成,提高大米质量品位,提供科学依据.     

多变量回归对大米中Cd元素LIBS分析精度比较

为了验证多变量回归分析提高激光诱导击穿光谱(LIBS)技术对大米中重金属元素Cd分析精度的可行性,在实验室条件下,对市售大米进行40个不同浓度梯度的氯化镉(Cd Cl2·52H2O)溶液浸泡,并对Cd污染大米进行干燥粉碎压片处理。采用优化后的LIBS系统参数采集压片大米中Cd元素的光谱信息,再利用阳极溶出伏安法(ASV)获取大米中Cd元素的真实含量。选取变量在211.03~299.96nm波长范围,运用偏最小二乘(PLS)与最小二乘支持向量机(LSSVM)对LIBS光谱信息与Cd真实浓度进行回归分析。PLS与LSSVM两种模型的定标集相关系数分别为0.9936,0.9992,验证集相关系数分别为0.9866,0.9946,交叉验证均方根误差RM SCEV分别为10.53,11.59,预测均方根误差RM SEP分别为10.52,10.80;定标集平均相对误差分别为17.2%,4.2%,验证集平均相对误差分别为12.1%,8.6%。试验结果表明,PLS与LSSVM两种方法均能对大米中Cd元素进行精确预测,且LSSVM的分析稳定性更好。本工作为大米中重金属Cd的LIBS快速、精确检测提供了理论参考。     

固相萃取-原子荧光光谱法测定大米中无机硒的含量

建立了固相萃取-原子荧光光谱法测定大米中无机硒含量的方法.大米粉样品0.5 g用水20 mL提取,离心后上清液中加入5 g·L-1氢氧化钠溶液,调至pH 4～7,过滤即得提取液.将提取液上SAX强阴离子交换柱进行固相萃取,收集洗脱液10 mL以分离无机硒,再采用原子荧光光谱法测定大米中无机硒的含量.结果表明:无机硒的质...     

水稻缺锌与环境关系的研究

综述了土壤中的锌含量及其分布规律,水稻缺锌发生的情况以及导致水稻缺锌的因素,表明水稻缺锌受多种因素影响。     

Elemental content of Vietnamese rice. Part 2. Multivariate data analysis

Rice samples were obtained from the Red River region and some other parts of Vietnam as well as from Yanco, Australia. These samples were analysed for 14 elements (P, K, Mg, Ca, Mn, Zn, Fe, Cu, Al, Na, Ni, As, Mo and Cd) by ICP-AES, ICP-MS and FAAS as described in Part 1. This data matrix was then submitted to multivariate data analysis by principal component analysis to investigate the influences of environmental and crop cultivation variables on the elemental content of rice. Results revealed that geographical location, grain variety, seasons and soil conditions are the most likely significant factors causing changes in the elemental content between the rice samples. To assess rice quality according to its elemental content and physio-biological properties, a multicriteria decision making method (PROMETHEE) was applied. With the Vietnamese rice, the sticky rice appeared to contain somewhat higher levels of nutritionally significant elements such as P, K and Mg than the non-sticky rice. Also, rice samples grown during the wet season have better levels of nutritionally significant mineral elements than those of the dry season, but in general, the wet season seemed to provide better overall elemental and physio-biological rice quality.     

国内外功能性稻米研究进展

以国内外研究功能性稻米对人体生理功能和潜在对复发性阿弗他溃疡影响的代表性论文为依据,综述了近年来有关功能性稻米对人体生理功能和对复发性阿弗他溃疡潜在影响的研究进展,包括:功能性稻米的定义、分类,国内外研究进展以及具有多种有生理作用的功能因子(铁、硒、γ-氨基丁酸、膳食纤维、抗性淀粉、黄酮和脂肪酸、花色苷类化合物),这些功能因子对人体多个系统有调节作用,对缓解复发性阿弗他溃疡的症状,减少其发生起着重要的作用。     

Activities and transfers of Pu and Am in rice samples from Camargue, France

In Camargue, the use of Rhone water does not cause any significant increase in additional Pu and Am contamination to rice. Ultra-trace quantities of these radionuclides in rice grains are mainly due to root transfer. Estimated transfer factors for Am and Pu isotopes are higher than mean values proposed in international report, however, are consistent with the 95% confidence intervals that are recommended.     

Ultra-sensitive determination of cadmium in rice and water by UV-vis spectrophotometry after single drop microextraction

In this work, a new method based on single drop microextraction (SDME) preconcentration using tetrachloromethane (CCl(4)) as extraction solvent was proposed for the spectrophotometric determination of cadmium in rice and water samples. The influence factors relevant to SDME, such as type and volume of extractant, stirring rate and time, dithizone concentration, pH, drop volume and instrumental conditions were studied systematically. Under the optimal conditions, the limit of detection (LOD) was 0.5 ng L(-1), with sensitivity enhancement factor (EF) of 128. The different maximum absorption wavelength caused by the different extraction acidity compared with some conventional works and the enhancement effect of acetone (dilution solvent) for the spectrophotometric determination were the two key factors of the high EF and sensitivity. The proposed method was applied to the determination of rice and water samples with satisfactory analytical results. The proposed method was simple, rapid, cost-efficient and sensitive.     

Analytical methods for pesticide residues in rice

Rice consumption has increased worldwide over recent decades, as it has become one of the most common foods. Although the analysis of environmental samples coming from rice areas has been well documented, there is less information regarding the analysis of pesticide residues in rice-grain samples.Rice (paddy, brown and white) can be considered a complex matrix, leading to difficulties in the application of the different multiresidue methods described in the literature. This review addresses and compares the principal extraction and clean-up methodologies [e.g., liquid-liquid extraction, solid-phase extraction, pressurized-liquid extraction, QuEChERS (quick, easy, cheap, effective, rugged and safe), gel-permeation chromatography and supercritical-fluid extraction - with QuEChERS-based methods being the most frequently employed].Traditionally, the determination of pesticide residues in rice has been based on gas chromatography with mass spectrometry (MS). But the application of new classes of pesticides has driven laboratories to increase the use of liquid chromatography with tandem MS. The limits of detection and quantification are in the ranges 0.09-90 μg/kg and 1-297 μg/kg, respectively, for the methodologies reported. These values agree with the current internationally-accepted maximum residue limits (MRLs).Based on the European Union (EU) database, more than 3000 analyses of pesticide residues in rice have been performed by official EU laboratories over the past decade. Of these, 6% reported pesticide residues above the MRLs.Physico-chemical properties can explain the occurrence of pesticides in rice commodities: lipophilic pesticides are frequently found in brown rice, whereas fungicides are mainly found in milled rice. Carbendazim, malathion, iprodione, tebuconazole, quinclorac and tricyclazole are the pesticides most frequently found in white rice, while buprofezin, hexaconazole, chlorpyrifos and edifenphos are most commonly found in paddy rice.Pesticide-residue concentrations can be affected during rice processing - with concentrations generally lower in the final products. However, few studies focusing on primary processing have addressed the setting of precise values applicable for the processing factors.     

Transfer of Metals from Soil to Crops in an Area near a Coal Gangue Pile in the Guqiao Coal Mine,China

A field survey was conducted to investigate the metal contamination in coal gangue, soils, and crops (rice and soybeans), and to evaluate the possible health risks to the local population through food chain transfer near a coal gangue pile in the Guqiao Coal Mine, China. Contamination levels of zinc, lead, cadmium, and copper in coal gangue, soils, and crops were measured, and bio-accumulation factors from soil to crops were determined; the health risks were calculated accordingly. Results showed that both coal gangue and soil contained high levels of cadmium (0.15 mg kg^?1and 0.20 mg kg^?1) exceeding the background value of the soil. The lead soil concentration was low (9.99 mg kg^?1), but lead in rice (0.38 mg kg^?1) exceeded the maximal permissible limit of 0.2 mg kg^?1. For some tissues of crops studied, there was a significant correlation between the bio-accumulation factor values and the corresponding soil metal concentrations that were best described by a power equation. Oral intake of zinc, cadmium, and copper through crops posed no health risk to local residents, although hazard indices for rice (0.87–2.88) and soybeans (0.06–0.09) suggested that ingestion of rice grains was unsafe for human health. Therefore, rice was inappropriate to be planted in the soil surrounding this coal mine.     

Tracer experiments on the behavior of radioiodine in the soil-plant-atmosphere system

In order to obtain information on the behavior of long-lived¹²⁹I in the soil-plant-atmosphere system, two different experiments, transfer factors and volatilization of iodine, have been conducted by radiotracer techniques using¹²⁵I. Soil-to-plant transfer factors varied very widely. Low values were found in tomato (0.0003) and rice (0.0019). The highest value for an edible part was seen in komatsuna,Brassica rapa L. (0.016), which is comparable to the IAEA recommended value of iodine for common crops (0.02). There was a tendency for older leaves to show higher concentrations than younger ones. The values for fruit, grain and beans were significantly lower than those for their leaves. Thus translocation of iodine with photosynthate from leaves into these plant organs was very small. Iodine in soil was found to be volatilized from the soil-rice plant system into the atmosphere as an organic iodine. Volatilization markedly decreased in the late cultivation period of rice plants.