氢化物发生-原子荧光光谱法同时测定保健食品中砷、汞的研究

为建立氢化物发生－原子荧光光法同时测定保健食品中砷、汞的方法、研究了酸度、硼氢化钾浓度、载气流量、灯电流以及原子化器高度等因素对测定的影响,在最佳条件下,砷、汞的检出限分别为０．０９８μｇ／Ｌ、０．００７μｇ／Ｌ。比较了湿法消化、微波消化两种试样前处理方法回收率的差异,砷的两种试样前处理方法的回收率分别为９２．３％￣９６．５％和９８．４％￣１０４．１％,汞分别为７６．１％￣８６．２％和９７．０％￣     

Comprehensive Identification of Immunodominant Proteins of Brucella abortus and Brucella melitensis Using Antibodies in the Sera from Naturally Infected Hosts

Brucellosis is a debilitating zoonotic disease that affects humans and animals. The diagnosis of brucellosis is challenging, as accurate species level identification is not possible with any of the currently available serology-based diagnostic methods. The present study aimed at identifying Brucella (B.) species-specific proteins from the closely related species B. abortus and B. melitensis using sera collected from naturally infected host species. Unlike earlier reported investigations with either laboratory-grown species or vaccine strains, in the present study, field strains were utilized for analysis. The label-free quantitative proteomic analysis of the naturally isolated strains of these two closely related species revealed 402 differentially expressed proteins, among which 63 and 103 proteins were found exclusively in the whole cell extracts of B. abortus and B. melitensis field strains, respectively. The sera from four different naturally infected host species, i.e., cattle, buffalo, sheep, and goat were applied to identify the immune-binding protein spots present in the whole protein extracts from the isolated B. abortus and B. melitensis field strains and resolved on two-dimensional gel electrophoresis. Comprehensive analysis revealed that 25 proteins of B. abortus and 20 proteins of B. melitensis were distinctly immunoreactive. Dihydrodipicolinate synthase, glyceraldehyde-3-phosphate dehydrogenase and lactate/malate dehydrogenase from B. abortus, amino acid ABC transporter substrate-binding protein from B. melitensis and fumarylacetoacetate hydrolase from both species were reactive with the sera of all the tested naturally infected host species. The identified proteins could be used for the design of serological assays capable of detecting pan-Brucella, B. abortus- and B. melitensis-specific antibodies.     

Characterisation and Antioxidant Activity of Crude Extract and Polyphenolic Rich Fractions from C. incanus Leaves

Cistus incanus (Cistaceae) is a Mediterranean evergreen shrub. Cistus incanus herbal teas have been used as a general remedy in traditional medicine since ancient times. Recent studies on the antioxidant properties of its aqueous extracts have indicated polyphenols to be the most active compounds. However, a whole chemical characterisation of polyphenolic compounds in leaves of Cistus incanus (C. incanus) is still lacking. Moreover, limited data is available on the contribution of different polyphenolic compounds towards the total antioxidant capacity of its extracts. The purpose of this study was to characterise the major polyphenolic compounds present in a crude ethanolic leaf extract (CEE) of C. incanus and develop a method for their fractionation. Superoxide anion, hydroxyl and DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging assays were also performed to evaluate the antioxidant properties of the obtained fractions. Three different polyphenolic enriched extracts, namely EAC (Ethyl Acetate Fraction), AF1 and AF2 (Aqueos Fractions), were obtained from CEE. Our results indicated that the EAC, enriched in flavonols, exhibited a higher antiradical activity compared to the tannin enriched fractions (AF1 and AF2). These findings provide new perspectives for the use of the EAC as a source of antioxidant compounds with potential uses in pharmaceutical preparations.     

光学玻璃用高纯度硝酸钾中微量钠的火焰原子吸收光谱法测试

介绍了火焰原子吸收法测试智能手机触摸屏用高纯度硝酸钾中微量钠的方法,优化了仪器的灯电流、狭缝宽度、乙炔与空气流量,研究了标准曲线选择、最大称样量及消电离剂用量等条件。该方法用于智能手机触摸屏用高纯度硝酸钾中微量钠的测试,检出限为0.002%,相对标准偏差为2.88%,回收率在95.00%~101.25%。     

蜂蜜中铅原子荧光光谱测定方法的改进

为改进蜂蜜中的铅的检测方法，用酸性活性炭吸附分离铁氰化钾试剂中铅，以pH计控制消化液的酸度。在最佳的条件下，铅在0．00—40．00μg/L范围内线性良好（r=0．9994）；方法检出限为0．21μg／L；相对标准偏差为4．1％-5．0％；样品加标回收率为93．2％-109．4％。该方法简单，快速，重现性好，灵敏度高，检出限低，结果令人满意。     

高效液相色谱-串联质谱法测定豆芽中4-氯苯氧乙酸钠

目的建立豆芽中4-氯苯氧乙酸钠的液相色谱-串联质谱测定方法。方法豆芽样品均质后以0.01mol/L氢氧化钠溶液提取,提取液经酸化后再用乙酸乙酯萃取,收集经离心分层的有机相,浓缩后用甲醇溶解进行测定分析。以甲醇和0.1%甲酸(FA)水溶液为流动相,采用Hypersil GOLD a Q(100 mm×2.1 mm,3μm)色谱柱分离,电喷雾电离负离子条件下以选择反应监测模式(SRM)检测。结果该方法检出限0.005 mg/kg,在1~100 ng/m L范围内具有良好线性,相关系数为0.9998。回收率为79.1%~104.7%,相对标准偏差低于5%(n=6)。结论该方法前处理简单快速,定性准确,灵敏度好,适用于豆芽中4-氯苯氧乙酸钠的残留检测。     

氢化物发生-原子荧光法同时测定食用鲜奶中的砷与汞

本文采用氢化物发生原子荧光法测定食用袋装鲜奶中的砷与汞.确定了仪器的最佳条件,探讨了酸介质、硼氢化钾浓度等对测定结果的影响.在选定的操作条件下,检出限为As:0.235μg/L和Hg:0.025μg/L,相对标准偏差为As:1.9%和Hg:1.6%.     

流动注射-火焰原子吸收光谱法联用 测定沙丁鱼中的痕量铅

本文以重金属铅(Pb)为测定对象,建立一种快速、高效、简便的检测方法测定食品中痕量的重金属,即流动注射(FI)空气混合法在线预富集与火焰原子吸收光谱法(FAAS)联用测定食品中痕量的重金属。样品溶液、络合剂和空气分别通过3条管子同时进样,金属离子和络合剂在线混合反应,其络合物流经编结反应器(KR)并吸附在其内壁,通入一段空气流,防止前后溶液混和并提高富集效果,用乙醇作为洗脱剂洗脱后送入火焰原子吸收光谱仪进行测定。与传统的流动注射与火焰原子吸收光谱法联用系统相比,此方法减少了样品的富集时间,达到了更好地吸附效果,提高了检测方法的灵敏度。该方法应用于沙丁鱼中重金属铅的测定,结果满意。     

高效液相色谱-串联质谱法快速测定海鳗鱼肉中 3种太平洋雪卡毒素

目的 建立了一种平行振荡方法萃取海鳗鱼肉中的3种太平洋雪卡毒素（P-CTX-1、P-CTX-2、P-CTX-3）,并采用高效液相色谱-电喷雾串联质谱法同时测定P-CTX-1、P-CTX-2、P-CTX-3残留量的分析方法。方法 海鳗等样品经甲醇并采用平行振荡方法提取,C18固相萃取柱净化后,采用高效液相色谱-电喷雾串联质谱分析测定。结果 以基质标准曲线外标法定量,线性范围为0.01?50.0 ng/g,相关系数均大于0.999（r≥0.999,n=3）,P-CTX-1、P-CTX-2、P-CTX-3的定量限分别为（LOQs,S/N=10）0.009、0.019、0.017 ng/g。以0.05、0.10、0.50 ng/g 3 个添加浓度水平进行方法验证,回收率分别为72.9~81.0%、63.0~77.9%、46.3~69.5%,相对标准偏差分别为2.3~2.7%、2.1~12.2%、6.1~15.3%。结论 该方法简便快速、灵敏度高,适用于鱼肉中同时快速检测3 种太平洋雪卡毒素。