超声辅助萃取-钨丝电热原子吸收光谱法测定痕量镉

镉对人体和动植物而言是一种非必需的元素,当其含量超过一定浓度就会产生毒性.由于镉在生物体内的半衰期长达1年之久,一旦进入生物体就不易排出.因此,测定食物样品中的镉对保证人类和动物的健康有重要的意义[1].     

Enzymatic hydrolysis of ammonia-treated rice straw

Rice straw pretreated with liquid anhydrous ammonia was hydrolyzed with cellulase, cellobiase, and hemicellulase. Ammonia-processing conditions were 1.5 g of NH₃/g of dry matter, 85°C, and several sample moisture contents. There were four ammonia addition time (min)-processing time (min) combinations. Sugars produced were analyzed as reducing sugars (dinitrosalicylic acid method) and by high-performance liquid chromatography. Monomeric sugars increased from 11% in the nontreated rice straw to 61% of theoretical in treated rice straw (79.2% conversion as reducing sugars). Production of monosaccharides was greater at higher moisture content and was processing time dependent. Glucose was the monosaccharide produced in greater amounts, 56.0%, followed by xylose, arabinose, and fructose, with 35.8, 6.6, and 1.4%, respectively.     

广州老人进食中国营养平衡米的营养调查

介绍了广州老人进食中国营养平衡米（简称平衡米）的效果。营养调查发现，广州老人Ca,P,Fe,Zn和Se摄入量分别为403，807，17，14mg/d/人和46μg/d/人，说明老人Ca,Zn,Se不足，原因是主食籼米矿物质营养不平衡，进食平衡米后。老人Ca,P,Fe,Zn和Se摄入量分别提高到1153，863，45，45mg/d/人和111μg/d/人。结果说明，进食平衡米可以提高广州老人矿物质营养水平，使老人健康长寿。     

MOLECULAR CHARACTERIZATION OF RICE Wx GENE

The complete nucleotide (nt) sequence of the rice waxy(Wx) gene, which is responsible for the synthesis of amylose in endosperm and pollen, has been determined by a combination of restriction mapping and nt sequence analysis of two overlapping genomic DNA clones. The entire gene is about 5.5 kb in length. The alignment of the nt sequence of the Wx gene from rice with those of maize (Klsgen, R. B. et al.) and barley (Rohde, W. et al.) revealed the presence of thirteen introns and fourteen exons. The full-length of Wx protein in cluding transit peptide is 609 amino acid (aa) residues. The calculated molecular weight of rice Wx preprotein is about 72 kD. There is no significant difference between the similarity scores of the aa sequence deduced from the rice Wx gene compared with those of maize and barley. However, the nt sequences of the 5'-end upstream, 3'-end downstream and introns of the rice Wx gene, as well as the aa sequence of the transit peptide region of the Wx preprotein have low similarity scor     

大孔球形纤维素固定化单宁的性能表征及其在黄酒中的应用

将单宁酸偶联在大孔球形纤维素载体上,制成一种新功能高分子材料-大孔球形纤维素固定化单宁。使用压汞法进行结构测定,发现其具有良好孔结构,平均孔径70nm,比表面积161.39m2/g,孔容13.53ml/g。流速与压力曲线表明,固定化单宁水力学特性好,可以耐受0.7Mpa的操作压力。化学溶剂浸泡实验表明,固定化单宁具有良好的化学稳定性和不溶性,符合食品用品的国家标准。800ml黄酒通过4ml固定化单宁层析柱处理,酒液清亮透明,保留原酒的香味和口感。蛋白质分离检测仪检测通过固定化单宁柱的酒液,高、中分子量的蛋白质大大减少,其中分子量在1万以上的蛋白质较未处理的酒液减少了65.7%。酒液化学成分分析显示,蛋白质的总量下降了33.4%,而氨基态氮却不变;铁离子含量由7.79×10-8mol/L降低至5.89×10-9mol/L,而且其他成分没有变化,所有指标均达到黄酒的国家标准。高温强化试验和低温贮藏试验表明,经固定化单宁层析柱处理的黄酒具有很好的稳定性。固定化单宁柱经0.1mol/LHCl洗脱再生,可以重复使用多次,而且保持性能稳定。     

Residues and dissipation of guadipyr in rice ecological system

A modified QuEChERs method with liquid chromatography-tandem mass spectrometry for analysis of guadipyr residue and dissipation in rice matrices, paddy soil and paddy water was developed and validated. Mean recoveries and relative standard deviations in paddy soil, paddy water, rice plant, rice straw, rice hull and husked rice matrices at three spiking levels were 83.1–116.5% and 1.6–9.5%, respectively. The half-life of guadipyr was determined in 2 years at three different field sites in China via a dissipation experiment. The half-lives of guadipyr in paddy water were 0.22–0.37 days, 0.24–3.33 days in paddy soil and 0.44–1.90 days in rice plant. The terminal residues of guadipyr ranged from ND (concentrations of guadipyr were below limit of detection) to 50 μg kg^?1 in paddy soil, 10–470 μg kg^?1 in rice hull, ND70 μg kg^?1 in husked rice and ND to 110 μg kg^?1 in rice straw. The results would be helpful in fixing maximum residue limit of guadipyr, a new insecticide, in rice.     

橙色红曲菌As3.4384及其诱变体发酵产物中的桔霉素和色素的高效液相色谱研究

对橙色红曲菌As3.4384及其诱变菌株大米固态发酵物中桔霉素和色素的HPLC分离进行了优化,采用Symmetry C18(250mm×4.6mmi.d.,5μm)色谱柱,流动相为乙腈-水(磷酸调pH3.0,77∶23,V/V),分别采用紫外检测器(UV=254nm)、荧光检测器(λex=331nm,λem=500nm)及两者串联对桔霉素和色素进行了监测。通过ESI-MS对色素进行了鉴定,并测定了经橙色红曲菌As3.4384及其诱变菌株于30℃发酵14d后的大米、糯米、小黄米、燕麦米和红米中桔霉素含量。结果表明:ESI-MS鉴定的两种色素分别为红曲菌素和红曲黄素,橙色红曲菌As3.4384发酵后的大米、糯米、小黄米、燕麦米和红米中桔霉素含量分别为151.4、100.5、5.06、80.5和150.5mg/kg,而诱变菌株发酵后的大米、糯米、小黄米、燕麦米和红米中桔霉素含量分别为0.218、3.86、0.223、2.45和4.05mg/kg。     

Ru (III) Schiff‐base complex anchored on nanosilica as an efficient and retrievable catalyst for hydration of nitriles

Transition metal catalyzed hydration of nitriles is an attractive methodology for amide synthesis, and hence recently attracted wide attention. It is one of the significant organic transformations as amides play a vital role in biological, pharmaceutical and industrial applications. In this work, we report the synthesis of a new solid supported Ru (III) Schiff base complex, Ru@imine‐nanoSiO₂ immobilized on nanosilica obtained from rice husk. The complex was characterized by FTIR, powder X‐ray diffraction, BET surface area measurement, UV–vis, SEM–EDX, TEM, ESR, X‐ray photoelectron spectroscopy and ICP‐AES analysis. Using Ru@imine‐nanoSiO₂ as the catalyst, the hydration of nitriles in i‐PrOH at 40 °C was studied which resulted in good isolated yields (60–99%). The catalyst can be recycled and reused up to 5^th cycle without any loss in activity. The products were characterized by FTIR, GC–MS and ¹H‐NMR spectroscopy and compared with authentic samples.     

Discrimination between 2AP producing and non‐producing rice rhizobacterial isolates using volatile profiling: a chemometric approach

2‐Acetyl‐1‐pyrroline (2AP) is known as a principal basmati aroma compound. The present study aims at discriminating rhizobacteria isolated from soils cultivated with basmati and non‐basmati rice for long duration. Volatile profiling was used as marker to discriminate the rhizobacterial isolates. Quantification of 2AP and other volatile compounds (VCs) produced by rhizobacteria was undertaken using HS‐SPME coupled with GC‐MS. Chemometrics tools such as hierarchical cluster analysis (HCA), principle component analysis (PCA) and multi dimensional scaling (MDS) were applied for volatile profiling of different isolates. Results showed significant discrimination of all 2AP producing (AP‐P) and non‐producing rhizobacterial isolates (AP‐NP) on the basis of their VC profile. This was validated by bacterial identification data as well. The frequency distribution for 2AP levels indicates that basmati isolates had higher frequency for 2AP production as compared to non‐basmati control. AP‐P and AP‐NP isolates have different VC profiling pattern irrespective of their origin. These isolates were found belonging to different groups when identified using 16S rDNA sequencing data. Chemometric analysis (PCA, HCA and MDS) helped to identify volatiles, which could be used as biomarker in discriminating the AP‐P and AP‐NP isolates. VC pattern of rhizobacteria could be used as volatile markers to distinguish between AP‐P and AP‐NP rhizobacterial isolates. Copyright © 2015 John Wiley & Sons, Ltd.     

固相萃取-高效液相色谱同时测定大米中的4种烟碱农药残留量

建立了高效液相色谱法同时测定大米样品中呋虫胺、噻虫胺、吡虫啉、吡虫清4种烟碱农药残留量的检测方法,对4种烟碱农药在ENVI-Florisil和Carb复合固相萃取柱上的保留行为进行了研究。样品用乙腈提取,固相萃取净化,HPLC-DAD分离检测,外标法定量。峰面积与标准溶液浓度在0.1～1.0 mg/L范围内呈良好的线性关系,相关系数大于0.9996。样品加标回收率为75.5%～96.0%,相对标准偏差为0.49%～4.36%(n=6),检出限达到0.004 mg/kg。