HPLC法测定红麻青贮饲料中的有机酸

运用高效液相色谱法对红麻青贮饲料中乳酸、乙酸、丙酸和丁酸4种有机酸的含量进行同时测定。采用0.02 mol/L NaH_2PO_4(pH=2.70)与甲醇作为流动相,在Dionex Ultimate 3000液相色谱仪,色谱柱为Thermo Hypersil BDS C18柱,流速1 mL/min,柱温30℃,检测波长210 nm,进样体积20μL条件下对青贮样品有机酸含量进行定性分析。结果表明,4种待测有机酸在预定检测范围内线性关系良好(R2≥0.9982),精密度变异系数5%,样品回收率在98.73%~102.79%之间。该方法操作简单准确,重复性好,可用于红麻青贮饲料中有机酸的测定。     

测定茶叶中22种有机磷农药残留的气相色谱法

建立了气相色谱法同时测定茶叶中22种有机磷农药残留的方法。样品用正己烷-乙酸乙酯(1:1,v/v)混合溶剂提取,经固相萃取小柱净化,采用CP-Sil 24 CB色谱柱分离,18MIN内在气相色谱上实现22种有机磷农药残留分析。采用外标法定量分析,在0.02～0.2μg/ml范围内线性关系良好,检出限为0.005～0.02 mg/kg,回收率为78%～120%,相对标准偏差为2.3%～7.7%。该方法简便、快速、准确、重现性好、灵敏度高,适用于实际检测。     

RP-HPLC法测定林下山参片中有机酸的含量

目的测定林下山参片中有机酸的含量。方法以食品中有机酸的含量测定标准GB/T 5009.157-2003,利用反相高效液相色谱法(RP-HPLC)测定林下山参片中富马酸、柠檬酸、马来酸、琥珀酸、酒石酸、香草酸和肉桂酸等7种有机酸的含量,采用XAqua C18色谱柱(4.6 mm×250 mm,5μm),以(NH4)2HPO4-H3PO4缓冲溶液(p H=2.7)为流动相分离测定前五种有机酸,流速为0.8 m L?min-1,柱温为30℃,检测波长210 nm;用Unitary C18色谱柱(4.6 mm×250 mm,5μm),以甲醇-0.5%冰乙酸梯度洗脱测定香草酸和肉桂酸含量,流速为1.0 m L?min-1,柱温30℃,检测波长为260 nm。结果 :马来酸、柠檬酸、反丁烯二酸、香草酸及肉桂酸的含量分别为0.015‰、2.619‰、0.030‰、0.009‰、0.025‰。结论首次通过RP-HPLC法对林下山参片中的有机酸进行含量测定,为林下山参新产品的科学服用提供了依据。     

采用反相高效液相色谱法同时测定杨梅果实中的有机酸

采用反相高效液相色谱法(RP-HPLC)研究了杨梅果实中有机酸的成分和含量,在C18柱(4.6mmID×250mm,4μm)上,采用紫外检测器(波长214 nm)进行检测,其流动相为0.04 mol/L的KH2PO4-H3PO4缓冲液,pH2.4,流速0.8mL/min,柱温35℃。检测所得7种有机酸标准曲线相关系数达0.999 0以上,平均回收率在88%～101%之间;变异系数RSD<3.06%。     

HPLC-MS/MS测定人参中噁霉灵农药残留量

目的 建立一种高效液相色谱串联质谱法(HPLC-MS/MS)测定人参中噁霉灵农药残留的方法。方法样品经乙腈匀浆提取,过C₁₈小柱后浓缩定容至1mL,0.22μm滤膜过滤,液相色谱-质谱法测定噁霉灵的残留量。液相色谱-质谱仪带电喷雾离子源,色谱柱：Agilent InfinityLab Poroshell 120SB-C₁₈(2.1mm×100mm,2.7-Micron),流动相：以乙腈、甲酸水溶液作为流动相进行梯度洗脱,流速0.25mL/min。柱温：40℃。结果 噁霉灵在0.005～0.4μg/mL范围内线性良好,相关系数r为0.998。样品加标回收率为80.9%～100.1%。结论 本方法可适用于人参中噁霉灵残留量的检测。     

QuEChERS-高效液相色谱-串联质谱法测定柑橘中13种磺酰脲类除草剂残留

建立了基于QuEChERS(快速Quick、简单Easy、廉价Cheap、有效Effective、耐用Rugged、安全Safe)前处理技术和高效液相色谱-串联质谱法同时测定柑橘中13种磺酰脲类除草剂的分析方法。通过对提取溶剂、净化剂、色谱条件、质谱条件等进行优化,确定样品用乙腈提取,经QuEChERS方法净化后,以0.1%甲酸水溶液和甲醇作为流动相,用Hypersil GOLD C18色谱柱(1.9μm 2.1mm×100mm)进行梯度洗脱分离,在高效液相色谱-电喷雾串联质谱仪正离子扫描多反应监测模式下测定,外标法定量。结果表明,13种目标物在1.0～100.0 ng/mL的范围内线性关系良好,相关系数(r)均不低于0.9960。在5.0、20.0、50.0μg/kg添加水平下的回收率为65.4%～110.0%,相对标准偏差(n=5)为3.7%～9.8%,检出限(以信噪比大于3计)为0.02～0.30μg/kg,定量限(以信噪比大于10计)为0.07～0.98μg/kg。该方法稳定可靠,灵敏度高,适用于柑橘中13种磺酰脲类除草剂残留的同时检测。     

紧压茶儿茶素和有机酸的组成分析

对云南紧茶、湖北青砖、浙江奉化紧压茶和浙江绿茶的儿茶素和有机酸分析表明，紧压茶加工过程中发酵时间越长，其儿茶素总量、有机酸含量越小；三种紧压茶有机酸含量分别为绿茶的354．6％、319．8％、209．0％，每种砖茶的草酸和琥珀酸的含量占到其有机酸总量的80％；三种紧压茶儿茶素含量分别为绿茶的21．8％、15．3％、4．7％。     

藏木香中木香烃内酯、去氢木香内酯含量测定方法的建立

目的建立高效液相色谱法(HPLC-DAD)同时测定藏木香中木香烃内酯和去氢木香内酯的含量。方法采用Kromasil C₁₈色谱柱,流动相为甲醇-水梯度洗脱,流速0.6 mL/min,检测波长225 nm,柱温25℃。结果木香烃内酯、去氢木香内脂的线性范围分别为0.117μg～7.5μg (γ=0.9999)和0.117μg～7.5μg(γ=0.9998)。结论该方法专属性强、准确性好、灵敏度高,可用于同时测定藏木香中两种特征性成分。     

利用HPLC法测定王草青贮饲料中的有机酸

建立并优化了测定王草青贮饲料中乳酸(LA)、乙酸(AA)、丙酸(PA)、丁酸(BA)的高效液相色谱检测方法.采用20 mmol/L NaH2PO4/H3PO4(pH2.65)-甲醇二元梯度洗脱程序在高效液相色谱-紫外检测器上完成4种有机酸的定性定量分析.结果表明,4种有机酸在0.015～2.25 mg/mL范围内的线性关系较好,相关系数R2≥0.999 4,精密度、稳定性的RSD均小于5％,样品回收率在88.44％～114.51％,LA、AA、PA、BA的检出限分别是1.40、3.31、3.57、5.23 μg/L.该方法简单、准确、重复性好,可用于王草青贮饲料中有机酸测定.     

超高效液相色谱-质谱/质谱法同时测定蔬菜中7种磺胺的残留量

为建立超高效液相色谱-质谱/质谱法(UPLC-MS/MS)同时测定蔬菜中7种磺胺残留量的方法。样品用1%乙酸乙腈提取，以C18色谱柱分离待测物，采用多反应监测(MRM)离子扫描模式，外标法进行定量，线性良好，相关系数均大于0.999。结果显示：7种磺胺的检出限为0.000 4～0.000 6 mg/kg，样品添加回收率为67.5%～94.1%，相对标准偏差均少于5.3%(n＝6)。该方法简单快捷、定量准确，可满足多种蔬菜中7种磺胺的残留检测要求。     

Comparative Assessment of the Efficacy of Various Nitrogen Fertilizers

Summary

The efficiency of N fertilizers is usually poor; often less than 50% of the applied N is taken up by the crop. This review focuses on various N fertilizers with respect to the significance of different N loss pathways, namely (i) ammonia volatilization, (ii) dinitrogen and nitrogen oxide emissions, and (iii) nitrate leaching. Further, the significance of biological N immobilization, ammonium fixation and, finally, the impact of nitrate vs. ammonium uptake on crop yield are also discussed. The reviewed literature shows that N fertilizers may differ markedly in their susceptibility to losses. There is, however, considerable scope to improve N efficiency of each N source by proper N management practices.     

Studies on natural repellents against potato tuber moth (Phthorimaea operculella Zeller) in country stores

Summary The effects of the leaves of five plant species, one from each of the generaAmbrosia, Anemone, Eupatorium, Eucalyptus andLantana, on potato tuber moth were investigated under indigenous storage conditions at the Central Potato Research Station, Shillong (1800 m above sea level). Their action was compared with that of a biological insecticide (spores ofBacillus thuringiensis), a chemical insecticide (carbaryl), and an untreated control. The data collected after six months storage on tuber damage, sprout damage and the rotting indicated that the leaves ofLantana aculeata provided most protection to the tubers, reducing damage from over 70% in the check to below 5%, and sprout damage from over 45% to below 3%. Next best wasEucalyptus globulus followed byB. thuringiensis. They may be used on tubers stored for table use or for seed as they had no adverse effect on germination or on the yield of a subsequent crop.     

Mineral composition of some traditional Mexican teas

Teas of plant origin traditionally consumed by the Mountain Pima of Chihuahua, Mexico, were analyzed for mineral nutritional content. Fe, Cu, Zn, Ca, and Mg composition was determined for native teas made from shoots ofTagetes lucida, T. filifolia, Elytraria imbricata, andHolodiscus dumosus, and from root xylem ofCeanothus depressus andPhaseolus ritensis. Native uses of these teas are also described.     

Novel food and non-food uses for sorghum and millets

Sorghum and millets have considerable potential in foods and beverages. As they are gluten-free they are suitable for coeliacs. Sorghum is also a potentially important source of nutraceuticals such antioxidant phenolics and cholesterol-lowering waxes. Cakes, cookies, pasta, a parboiled rice-like product and snack foods have been successfully produced from sorghum and, in some cases, millets. Wheat-free sorghum or millet bread remains the main challenge. Additives such as native and pre-gelatinised starches, hydrocolloids, fat, egg and rye pentosans improve bread quality. However, specific volumes are lower than those for wheat bread or gluten-free breads based on pure starches, and in many cases, breads tend to stale faster. Lager and stout beers with sorghum are brewed commercially. Sorghum's high-starch gelatinisation temperature and low beta-amylase activity remain problems with regard to complete substitution of barley malt with sorghum malt . The role of the sorghum endosperm matrix protein and cell wall components in limiting extract is a research focus. Brewing with millets is still at an experimental stage. Sorghum could be important for bioethanol and other bio-industrial products. Bioethanol research has focused on improving the economics of the process through cultivar selection, method development for low-quality grain and pre-processing to recover valuable by-products. Potential by-products such as the kafirin prolamin proteins and the pericarp wax have potential as bioplastic films and coatings for foods, primarily due to their hydrophobicity.     

In vitro antimicrobial activity of different accessions ofSolanum commersonii Dun. from Uruguay

Summary The in vitro antimicrobial activity of extracts from accessions ofSolanum commersonii Dun. collected in the south of Uruguay was investigated against five microorganisms including the pathogenRalstonia solanacearum. A total of 30 extracts corresponding to organic and aqueous extracts were studied. Interestingly, most of the positive results for growth inhibition were againstR. solanacearum. The extracts were also analyzed for the presence of glycoalkaloids and lectins. Six of the ten aqueous extracts showed lectin presence and a wide variation in the type and amounts of glycoalkaloids, was found. Results indicate that there is no clear relationship between the antimicrobial activity against the five microorganisms screened and the presence or amounts of lectins and glycoalkaloids, traditionally regarded as possible antimicrobial metabolites in theSolanum genus, which indicates the presence of as yet unidentified antimicrobial compounds.     

Extreme resistance to infection by potato virus X in genotypes of wild tuber-bearingSolanum species

Summary Clones derived from thirty-one different accessions (nineteen of Argentine origin) belonging to eightSolanum species were screened for resistance to infection by potato virus X strain cp (PVX cp) by mechanical inoculation of plantlets that had been micropropagated in vitro. Estimates of PVX multiplication obtained by enzyme linked immunosorbent assay and slot blot nucleic acid hybridization allowed the identification of resistant clones derived from five accessions belonging toS. commersonii S. oplocense, S. sparsipilum andS. tuberosum andigena. Resistant genotypes supported PVX concentrations 5 to 15 times smaller than did the susceptible control cultivar Spunta. Graft inoculation test confirmed the presence of extreme resistance similar to that conferred by the ‘immunity’ gene X¹ (also called RX_act).     

Cyanobacteria Secondary Metabolites as Biotechnological Ingredients in Natural Anti-Aging Cosmetics: Potential to Overcome Hyperpigmentation,Loss of Skin Density and UV Radiation-Deleterious Effects

The loss of density and elasticity, the appearance of wrinkles and hyperpigmentation are among the first noticeable signs of skin aging. Beyond UV radiation and oxidative stress, matrix metalloproteinases (MMPs) assume a preponderant role in the process, since their deregulation results in the degradation of most extracellular matrix components. In this survey, four cyanobacteria strains were explored for their capacity to produce secondary metabolites with biotechnological potential for use in anti-aging formulations. Leptolyngbya boryana LEGE 15486 and Cephalothrix lacustris LEGE 15493 from freshwater ecosystems, and Leptolyngbya cf. ectocarpi LEGE 11479 and Nodosilinea nodulosa LEGE 06104 from marine habitats were sequentially extracted with acetone and water, and extracts were analyzed for their toxicity in cell lines with key roles in the skin context (HaCAT, 3T3L1, and hCMEC). The non-toxic extracts were chemically characterized in terms of proteins, carotenoids, phenols, and chlorophyll a, and their anti-aging potential was explored through their ability to scavenge the physiological free radical superoxide anion radical (O₂^•−), to reduce the activity of the MMPs elastase and hyaluronidase, to inhibit tyrosinase and thus avoid melanin production, and to block UV-B radiation (sun protection factor, SPF). Leptolyngbya species stood out for anti-aging purposes: L. boryana LEGE 15486 presented a remarkable SPF of 19 (at 200 µg/mL), being among the best species regarding O₂^•− scavenging, (IC₅₀ = 99.50 µg/mL) and also being able to inhibit tyrosinase (IC₂₅ = 784 µg/mL), proving to be promising against UV-induced skin-aging; L. ectocarpi LEGE 11479 was more efficient in inhibiting MMPs (hyaluronidase, IC₅₀ = 863 µg/mL; elastase, IC₅₀ = 391 µg/mL), thus being the choice to retard dermal density loss. Principal component analysis (PCA) of the data allowed the grouping of extracts into three groups, according to their chemical composition; the correlation of carotenoids and chlorophyll a with MMPs activity (p < 0.01), O₂^•− scavenging with phenolic compounds (p < 0.01), and phycocyanin and allophycocyanin with SPF, pointing to these compounds in particular as responsible for UV-B blockage. This original survey explores, for the first time, the biotechnological potential of these cyanobacteria strains in the field of skin aging, demonstrating the promising, innovative, and multifactorial nature of these microorganisms.     

Marine Pharmacology in 2009–2011: Marine Compounds with Antibacterial,Antidiabetic, Antifungal,Anti-Inflammatory,Antiprotozoal, Antituberculosis,and Antiviral Activities; Affecting the Immune and Nervous Systems,and other Miscellaneous Mechanisms of Action ?

The peer-reviewed marine pharmacology literature from 2009 to 2011 is presented in this review, following the format used in the 1998–2008 reviews of this series. The pharmacology of structurally-characterized compounds isolated from marine animals, algae, fungi and bacteria is discussed in a comprehensive manner. Antibacterial, antifungal, antiprotozoal, antituberculosis, and antiviral pharmacological activities were reported for 102 marine natural products. Additionally, 60 marine compounds were observed to affect the immune and nervous system as well as possess antidiabetic and anti-inflammatory effects. Finally, 68 marine metabolites were shown to interact with a variety of receptors and molecular targets, and thus will probably contribute to multiple pharmacological classes upon further mechanism of action studies. Marine pharmacology during 2009–2011 remained a global enterprise, with researchers from 35 countries, and the United States, contributing to the preclinical pharmacology of 262 marine compounds which are part of the preclinical pharmaceutical pipeline. Continued pharmacological research with marine natural products will contribute to enhance the marine pharmaceutical clinical pipeline, which in 2013 consisted of 17 marine natural products, analogs or derivatives targeting a limited number of disease categories.