A novel indicator system for catalytic spectrophotometric determination and speciation of inorganic selenium species （Se（Ⅳ）, Se（Ⅵ）） at trace levels in natural lake and river water samples

A novel catalytic kinetic method is proposed for the determination of Se(IV), Se(VI), and total inorganic selenium in water based on the catalytic effect of Se(IV) on the reduction of Celestine blue by sodium sulfide at pH 7.0 phosphate buffer. The fixed-time method was adopted for the determination and speciation of inorganic selenium. Under the optimum conditions, the two calibration graphs are linear with a good correlation coefficient in the range 2–20 and 20–200 μg·L⁻¹ of Se(IV) for the fixed-time method at 30°C. The experimental and theoretical detection limits of the developed kinetic method were found to be 0.21 and 2.50 μg·L⁻¹ for the fixed-time method (3 min). All of the variables that affect the sensitivity at 645 nm were investigated, and the optimum conditions were established. The interference effect of various cations and anions on the Se(IV) determination was also studied. The selectivity of the selenium determination was greatly improved with the use of the strongly cation exchange resin such as Amberlite IR120 plus as long as chelating agents of thiourea and thiosulphate. The proposed kinetic method was validated statistically and through recovery studies in natural water samples. The relative standard deviations (RSDs) for ten replicate measurements of 2, 10, and 20 μg·L⁻¹ of Se(IV) change between 0.35% and 5.58%, while the RSDs for ten replicate measurements of 3, 6, and 12 μg·L⁻¹ of Se(VI) change between 0.49% and 1.61%. Analyses of a certified standard reference material (NIST SRM 1643e) for selenium using the fixed-time method showed that the proposed kinetic method has good accuracy. The Se(IV), Se(VI), and total inorganic selenium in lake and river water samples have been successfully determined by this method after selective reduction of Se(VI) to Se(IV).     

基于磁性纳米材料Fe3O4/C吸附测定水样中痕量结晶紫的方法

采用溶剂热/水热法合成了磁性纳米粒子Fe3O4/C,利用透射电镜、傅里叶变换红外光谱、X射线衍射等对其进行表征。将该材料用作磁性固相萃取吸附剂萃取富集水中的痕量结晶紫,之后用紫外分光光度法测定,建立了一种分离富集和检测结晶紫的方法。考察水样酸度、搅拌时间和吸附温度对结晶紫吸附率的影响。结果显示,在pH 8.0、搅拌时间10 min、吸附温度25 ℃条件下,该材料对结晶紫具有良好的吸附性,用乙醇-0.5 mol/L对甲苯磺酸（9∶1,V/V）可以很好地解吸。在优化实验条件下,方法对结晶紫的检出限为0.024 mg/L。对赣江水样品中的结晶紫进行检测,加标回收率为105.8%～108.4%,相对标准偏差为3.6%～6.1%。     

水样品放射性活度以土壤样为标准的测量误差修正

以已知活度的土壤样为标准对水样中的放射性活度用高纯锗(HPGe)γ谱仪进行测量,由于两样品在组成成分特别是密度上的差别,会给测量结果带来一定误差。为了修正这一刻度误差,本文采用蒙特卡罗方法,通过分别模拟计算HPGe探测器对水样和土样中238U2、32Th2、26Ra4、0K等核素特征γ射线的探测效率,得到了以土样为标准测量水样核素活度引入的刻度误差。对238U为12%,其余三种核素均小于5%的误差,从而建立起了对这一刻度误差进行修正的方法。     

2-(2-噻唑偶氮)-5-磺丙氨基苯酚与镍(Ⅱ)显色反应的研究及其应用

研究了2-(2-噻唑偶氮)-5-磺丙氨基苯酚(TASPAP)与镍(Ⅱ)的显色反应,发现该试剂与镍(Ⅱ)在pH6.46的Clark-Lubs缓冲溶液中形成2∶1的稳定紫红色络合物。该络合物的最大吸收波长λmax在550 nm处,在10 mL溶液中镍质量在0~14μg服从比尔定律,测定的表观摩尔吸光系数ε550为6.346×104L.mol-1.cm-1。所拟方法用于合金钢样品和水样中微量镍的测定,加标回收率在98%~101%之间。     

ICP-OES测定环境水样中的钾-40

建立了利用电感耦合等离子体发射光谱仪(ICP-OES)测定环境水样中钾-40的方法。此方法标准工作曲线线性关系良好,检出限为0.001 Bq/L,相对标准偏差小于1.5%,相对误差小于4.0%,加标回收率在94.1%~105.5%之间,具有前处理简单、检出限低、精密度和准确度高、干扰小等优点,值得推广应用。     

ICP-MS测定环境水样中痕量铀

环境中天然放射性元素越来越引起人们的重视,其中特别关注的是水体中的铀的危害。文章阐述了用电感耦合等离子体质谱(ICP-MS)对环境水样中痕量铀的测定方法及结果,分析了环境水样中是否存在健康风险。     

同种浆料和水样中大胶黏物和微胶黏物的测定

在标准TAPPI大胶黏物实验中,通过测定首次筛出的5加仑（18．93L）筛出物中的微胶黏物含量,可确定微胶黏物附聚所带来的胶黏物问题的原因。这个实验方法可用来确定回收纸样（如标签纸、涂蜡OCC）在不同碎浆条件下微胶黏物的形成趋势,也可用来确定回收过程中去除大胶黏物或形成微胶黏物的不同部件的操作效率（如筛选、净化、浮选或溶气浮选槽）。大胶黏物和附聚的微胶黏物是使用同一种原浆、用相同的带有0．006in（0．15mm）筛孔的细缝筛筛选时截留在筛网上的,所以从每个样品得到的结果都具有可比性。另外还介绍了微胶黏物的加速附聚实验的初步结果。     

木聚糖酶在麦草制浆造纸中的应用

木聚糖酶是一类可以将木聚精降解成低木聚糖或木精的复合酶系,其广泛应用于麦草浆的制浆造纸过程中.文章介绍了木聚糖酶用于麦草原料的预处理、麦草浆的辅助漂白、麦草浆的纤维改性以及酶处理后水样成分的变化,并对酶处理后溶出物质的能源化提出了展望.     

PAN流动注射分光光度法测定水样中的镍(Ⅱ)

在pH8.0的NH3-NH4Cl缓冲溶液中,在非离子表面活性剂吐温80存在下,Ni2 与1-(2-吡啶偶氮)-2-萘酚(PAN)生成红色络合物,据此建立了流动注射分光光度法测定水样中痕量镍(Ⅱ)的分析方法.测定结果表明本方法的灵敏度、准确度都较高,且流路简单,操作方便,抗干扰较好.测定河口湖泊水时,在0.1～1200 μg/L浓度范围内具有良好的线性关系,0.1～2 μg/L浓度范围内相关系数为0.9998,2～100 μg/L浓度范围内相关系数为0.9994,100～1200 μg/L浓度范围内相关系数为0.9995,检出限为0.05 μg/L,回收率为98.2%～105.9%,用40 μg/L标准溶液进样的相对标准偏差为1.47%(n=11).加入掩蔽剂后该方法用于实际水样分析,结果让人满意.