三种芦荟凝胶多糖的提取与含量测定

采用先醇沉后水提的方法从三种芦荟凝胶中提取凝胶多糖,以甘露糖标准液绘制标准曲线,用国标法经苯酚-硫酸显色,于489nm处测定多糖含量。结果表明：库拉索芦荟凝胶多糖含量4.90×10^-1%,中华芦荟多糖含量为4.745×10^-1%,木立芦荟多糖含量为4.605×10^-1%。为芦荟进一步开发利用提供重要理论依据。     

Evaluation of Analytical Methods for Boron Determination in Maize Shoots

For the comparison of the digestion and spectroscopic determination methods used to measure boron (B) concentrations in maize shoots, increasing doses of boron (0, 2.5, 5, and 10 mg kg^?1 B) were applied to soil and maize plants (Zea mays L.) cultivar “Euralis Es Armandi” (FAO 640). The plants were grown under greenhouse conditions. Dried and ground maize shoots were digested according to two digestion procedures of microwave and dry ashing. Boron concentrations were determined using spectrophotometer and inductively coupled plasma-optical emission spectrometry (ICP-OES). The concentrations of boron influenced statistically (p < 0.01) due to the B applications and analysis methods. Spectrophotometric measurement of B amounts of the samples prepared with microwave digestion method was found irrelevant with other indicated methods. However, the ICP-OES measurements were found compatible with the dry ashing also with microwave digestion and suggested as a suitable method to determine boron contents of the maize shoots.     

分光光度法测定土壤铬的几点改进建议

土壤重金属监测是环境监测的重要环节;而土壤铬的测定又是土壤重金属监测的重要组成部分;通常用分光光度法测定土壤铬的过程中,要用叠氮化钠来还原过量的高锰酸钾,但叠氮化钠的使用,使实验存在一定危险性,因此,经过几年的实践摸索,得出结论:使用尿素与亚硝酸钠代替叠氮化钠,还原过量的高锰酸钾,以此能有效地降低实验的危险性。     

黔东南州稻田土壤中有效铁锰铜锌的含量

为黔东南州合理施用微肥提供依据,利用火焰原子吸收光谱法测定采自贵州省黔东南州16个县市稻田土壤有效铁、锰、铜、锌的含量。结果表明:在黔东南州16个县市稻田土壤中有效铁的平均含量为202.88 mg/kg,变异范围为1.38~478.88 mg/kg;有效锰的平均含量为38.97 mg/kg,变异范围为25.60~144.31mg/kg;有效铜的平均含量为6.63mg/kg,变异范围为4.45~8.29mg/kg;有效锌的平均含量值为11.07mg/kg,变异范围为4.57~21.85mg/kg。贵州省黔东南州稻田土壤中有效铁、锰含量处于高等水平,有效铜、锌含量处于中等水平。     

树脂包衣尿素溶出氮的测定方法比较与分析

新型可控树脂包衣尿素以复合树脂材料为原料,可控制氮素的释放,以满足作物全生育期对氯素的需求.文章主要介绍树脂包衣尿素在恒温25℃水中溶出氮含量的两种测定方法:分光光度法与数粒法,并对所得数据进行了分析.结果表明:不同释放天数的树脂包衣尿素能在预定释放期内,将氮素缓慢释放出来;分光光度法和数粒法测定不同释放天数的树脂包衣尿素溶出氯相关性均较好.     

不同前处理方法对测定植物性饲料微量元素铜、铁含量的影响

本试验采取有代表性的饲料原料,分别采用干灰化法、湿消化法和酸溶解法3种不同的处理方法处理饲料样本测定微量元素铜(Cu)、铁(Fe)含量。试验以精确度、准确度、所需时间、操作的难易程度等为指标综合比较不同处理方法对饲料分析的实际意义。实验表明:国标干灰化法需专门设备,灰化时间较长;湿法消化法和酸溶解法可以达到国标法的精确度和准确度,在进行植物性饲料微量元素Cu、Fe的测定时,可以用湿消化法和盐酸溶解法代替国标法。     

Grafting-induced seed gossypol levels by demethylation of (+)-delta-cadinene synthase genes in upland cotton

Two-year-grafting experiments within and between Gossypium barbadense and Gossypium hirsutum accessions were conducted to study the source, transfer, and alteration of gossypol and methylation of (+)-δ-cadinene synthase (CDN) genes along with whole chromosomes of A01, A04, A11, D01, D05, and D11, harbouring the cotton CDNs, using the whole genome bisulfite sequencing (WGBS) method. The results revealed that although a glandless line used in this study had a low level of gossypol in the seeds, it did not contain any pigment glands, indicating that expression pathways of gland and gossypol were under genetic control of different loci in cotton. Grafts with glandless rootstocks produced significant amounts of total gossypol in the seeds, clearly demonstrating that the source of gossypol biosynthesis was not specific to the root. Heterografts consisting of scion GN, a glandless line, and scion TM-1 grafted on Pima 3-79 rootstocks caused increased total seed gossypol levels whereas homograft TT had decreased total seed gossypol levels. Alteration of total gossypol levels was also associated with gland density, and DNA demethylation levels of (+)-δ-cadinene synthase genes.     

近红外光谱法估测饲料用裸大麦品质的应用研究

应用近红外光谱分析法(NIRS)估测饲料用裸大麦中粗蛋白质、粗纤维、粗灰分、水分的含量与化学万法之间相关性高,误差小。42份样品定标结果,复合相关系数(MR)分别为0.9762、0.7826、0.6158、0.9408,标准误误(SE)为0.3210、0.1930、0.3140、0.1520,22份裸大麦样品检验结果,相关系数(r)分别为0.933、0.397、0.409、0.762,估测标准误(SEP)为0.421、0.197、0.157、0.512;估测13种氨基酸含量,除色氨酸和胱氨酸外,相关系数均在0.9以上,变异系数(C.V.)均小于6%。说明采用NIRS方法测定裸大麦的粗蛋白、粗纤维、粗灰分、水分以及氨基酸含量不仅可行,而且具有快速、简便、低耗、准确等优点。     

贝类产品中石油烃测定的不确定度评估

不确定度是一个合理表征测量结果分散性的参数,具有广泛的应用性和实用性。不确定度的评估对实际检测工作的质量控制具有重要意义。本文研究了荧光分光光度计法测定贝类产品石油烃含量过程中所产生的不确定度。分别考虑了油标准储备液本身、储备液稀释过程、标准曲线拟合、样品的称量、皂化过程、样品的溶解及重复测定过程等各方面因素。评估了各项因子的不确定度、合成不确定度以及扩展不确定度。结果表明,在现场特定情况下,当贝类产品中石油烃的浓度为9.08mg/kg时,其相对合成不确定度为11.1%,扩展不确定度为2.02mg/kg(k=2)。贝类产品石油烃测定的不确定度主要由样品的皂化反应处理过程中的损失所致。因此减少皂化反应过程中的损失,提高皂化样品的回收率,可以有效的减少测量过程中的不确定度,从而提高检测结果的正确度。     

鲑鱼肉和饲料中类胡萝卜素的分析方法

鱼肉和饲料中的虾青素分析方法对于研究鲑鱼肉色质量及饲料对其影响至关重要。本研究建立了北极红点鲑鱼肉类胡萝卜素的正相高效液相色谱分析方法。该方法采用正己烷与异丙醇等度洗脱(93∶7,体积比),流速1.1mL/min,可实现18min内4种常见鲑鱼类胡萝卜素包括虾青素、角黄素、β-胡萝卜素和玉米黄素的有效分离。研究结果显示,虾青素的回收率和变异系数值分别为97%和1.5%。正己烷和异丙醇复合溶剂提取的鱼肉样品与丙酮提取并经氨基固相萃取小柱纯化后的鱼肉样品的虾青素含量接近,但比丙酮提取样品中虾青素含量略低。正相高效液相色谱法和分光光度法测定鱼肉虾青素含量分别为1.43mg/L和2.43mg/L。研究同时建立了鲑鱼饲料虾青素分析方法。研究结果表明,-80℃冷冻结合氨基固相萃取小柱纯化可去除饲料样品中的大部分脂肪。饲料中虾青素酯皂化的最佳条件为:0.10mol/L甲基化氢氧化钠,22℃,20min;或者0.12mol/L甲基化氢氧化钠,4℃,3h。研究结果表明,两种方法可用于鲑鱼肉和饲料中的虾青素分析,为相关研究带来方便。