紫外分光光度法测定肉制品中亚硝酸盐

在酸性条件下 ,亚硝酸盐与间苯二酚及锆氧离子反应生成有色螯合物 ,建立了一种简易快速的测定食品中微量亚硝酸盐的方法。优化了波长、酸度、显色剂用量、显色时间等实验条件 ,并由正交实验进一步验证。对猪肉、午餐肉、腊肠、香肠几种样品中的亚硝酸根离子进行测定 ,回收率达 90 %以上     

基于顺序注射分析的海水亚硝酸盐快速检测方法研究

为实现海水亚硝酸盐的快速检测,使测量过程更适用于在线监测,对前期已有的顺序注射分析技术进行了优化,结合自主研制的Z型高灵敏度液芯波导样品池和多适应环管器,基于分光光度检测方法,在不完全显色反应的基础上,建立了一种海水亚硝酸盐快速全自动检测方法。进样技术中高精度注射泵与多通道选择阀配合,顺序吸入样品和试剂至储液盘管后,再反推至混合盘管,期间发生不完全显色反应,并最终由注射泵将显色混合溶液缓推过Z型液芯波导样品池,同步流动检测溶液吸光度变化,结合朗伯比尔定律最终获取待测亚硝酸盐溶液浓度。为达到稳定且快速分析的目的,分析了测量方法中几个关键参数,如不完全显色反应时间、检测时流速和盐度对测量结果的影响,寻求最佳的技术及参数组合。不完全显色反应研究结果表明,在10~60 s显色时间范围内,吸光度检测结果的相对标准误差（RSD）均不超过1.64%,说明10~60 s的显色时间对本方法无影响,因此选择10s作为快速检测方法的显色反应时间。通过对不同流速情况下样品检测结果的分析发现,流速过快会导致检测不稳定,过慢则不利于快速分析,选择吸光度测量较为稳定的10,11.6,13和15 μL·s-1四个流速,对测量结果的稳定性和重复性进行分析,结果表明,上述四个流速下的线性效果都很好,因此,选择最快的15 μL·s-1作为该方法的检测流速。为验证该方法对盐度的敏感性,以适应淡水和大范围海水为出发点,研究分析了0~35盐度范围内,三种不同浓度（150,250,350 μg·L-1）亚硝酸盐溶液的吸光度变化情况,得到的RSD分别为1.39%,2.03%和1.28%,证明盐度对本方法的吸光度测量基本无影响。对80,150和250 μg·L-1亚硝酸盐标准溶液平行测定11次得到的RSD分别为2.13%,1.07%和1.83%,说明本方法精密度较好。通过对空白样品进行10次平行样测量,计算得到本方法检出限为37 μg·L-1（约0.5 μmol·L-1）。为验证本方法的可信度,利用该快速检测方法和《海洋调查规范》标准测量方法对同一批次亚硝酸盐标准溶液制作标准曲线,二者的R2均大于0.999,对同一浓度样品两种方法得到的测量结果数据拟合线性回归方程为y=1.046 1x-0.005 7,R2=0.999 6,说明两种检测方法结果高度一致,更进一步验证了该研究快速测量方法的可行性和可靠性。亚硝酸盐快速检测方法测样速率高达50样·h-1,与传统的人工检测和流动注射分析方法相比,亚硝酸盐的测量耗时从十几分钟缩短到1 min左右,检测分析过程中样品和试剂消耗量极少,测量过程重复性好,整个测量过程全自动进行,操作更为简单智能,避免了人工介入带来的误差,使得基于分光光度的营养盐要素在线及原位检测系统更加小巧、快速和低耗,更适用于现场在线及长时间序列监测,具有很广的应用范围和较好的应用前景。     

TNT基炸药机械加工用切削液

针对TNT基炸药及其机械加工特点，设计出对人和环境友好的CFE和ICFE系列TNT基炸药机械加工专用水基切削液配方，根据切削液的防锈性能、切削液与TNT基炸药作用的变色特性对配方进行了筛选和评价。     

双氧水分光光度法测定Ni-TiO2纳米复合镀层中TiO2的共析量

在硫酸介质中,Ti~(4 )与H_2O_2生成桔黄色络合物,最佳测定波长为407nm;研究了酸度、显色剂用量、显色时间及共存离子对测定结果的影响。结果表明,钛在0—10.0μg/mL范围内遵守朗伯比耳定律,其表观摩尔吸光系数为1.072×103L·mol~(-1)·cm~(-1)。此方法简便、准确,可用于Ni-TiO_2纳米复合镀层中TiO_2共析量的测定。     

分光光度法测定镧汞齐中的镧

以偶氮胂 为显色剂 ,氯乙酸 -氢氧化钠为缓冲溶液 ,用分光光度法直接测定镧汞齐中镧含量。最佳的显色酸度为 p H2 .8— 3.0 ,最佳测定波长为 6 6 0 nm。镧含量在 0— 75 μg/ 2 5 m L范围内吸光度符合比耳定律 ,线性回归方程为 A=- 0 .0 2 4 8+0 .0 132 C,相关系数 r=0 .9992 ,配合物的摩尔吸光系数 ε为 4 .2 8×10 4L· mol-1· cm-1,回收率为 97.3%— 10 3.6 %。本法显色稳定性好 ,灵敏度高 ,操作简便 ,快速     

分光光度法测定铋系超导材料中钙

在pH=10.6的NH3-NH4Cl缓冲溶液中,钙离子和酸性铬蓝K显色,于498nm波长处以试剂空白作参比,测定该显色液的吸光度。建立了铋系超导前驱粉(Bi2Sr2Ca2Cu3Ox)中直接测定钙含量的方法。试样中大量存在的锶不干扰测定,用柠檬酸溶液作掩蔽剂,消除了铜的干扰。ε=9.0×103L·mol-1·cm-1,Ca在0—50μg·25mL-1范围内吸光度和浓度有良好的线性关系,回归系数r=0.9994。对合成样品进行6次测定,相对误差为-0.93%。对两种实际样品分别进行6次测定,RSD分别为1.63%和1.19%。     

茯砖茶中黄酮的提取及含量测定

研究了茯砖茶中黄酮的最佳提取及测定条件,以95％乙醇为溶剂,加热回流提取茯砖茶中的黄酮,采用分光光度法检测黄酮含量.在料液比为1∶20g/mL,加热回流60min时,黄酮的提取率最高;当波长为416nm,0.1mol/LAlCl3-甲醇显色液与HAc-NaAc缓冲液(pH=4.0)的体积比为1∶1,显色时间为15min时,吸光度最大.对照样品的线性回归方程为A=0.0203+0.0176C(μg/mL),相关系数r=0.9997,线性范围10-50μg/mL,检出限2.5μg/mL;测得茯砖茶样品中黄酮的含量为1.80％,RSD为1.27％(n=5),对照样品的平均加标回收率为99.0％-102.8％.方法操作简便、快速、准确,能满足茯砖茶中总黄酮的提取和检测的要求.     

烟草中多酚总含量的检测

采用分光光度法在540nm处进行烟草中的多酚总量测定实验.研究了显色时间和显色温度对多酚总量检测的影响,实验证明,显色温度和显色时间对绿原酸标准溶液的吸光度影响较大,而对烟草样品溶液影响较小.对不同类型的烟叶进行测定,多酚含量差异明显.该方法的平均加标回收率为95.25%,相对标准偏差RSD为1.10%-3.35%.     

混合酸浸提-火焰原子吸收法测定土壤中的铅

本文主要研究了土壤中微量元素铅的测定条件,采用混合酸在沸水浴中加热浸提后,直接上机测定.最佳测定条件是水浴温度为100℃,浸提时间为120min,混合酸为HNO3+HCl+H2O(1+1+2)该方法具有样品前处理简便,测定快速、准确、空白值低等特点,样品加标回收率为92%-102%,RSD为0.83%-6.38%,并用国家标准物质污染农田土壤标样进行验证,其结果吻合.     

微波灰化-分光光度法测定烟草料液中的铅

研究了用微波灰化样品,对磺酸基苯亚甲基若丹宁(SBDR)分光光度法测定烟草料液中的铅,烟草料液样品用微波灰化,灰烬用硝酸溶解,样品溶液中的铅用SBDR显色,显色络合物最大吸收波长为520nm,铅含量在0—2.0μg/mL内符合比耳定律,方法实际用于几种烟草料液中铅含量的测定,结果令人满意。     

Effect of In3+ ions on the electrochemical performance of the positive electrolyte for vanadium redox flow batteries

Influence of In³⁺ ions on electrochemical performance of positive electrolyte for vanadium redox flow battery was investigated in this paper. The electrochemical activity and kinetics of V(IV)/V(V) redox couple can be enhanced by the addition of In³⁺ ions, and the optimal concentration of In³⁺ ions was found at 10 mM. At this condition, the oxidation peak current with 10 mM In³⁺ ions is 46.6 mA at a scan rate of 20 mV s^?1, larger than that of pristine electrolyte (41.8 mA), and the standard rate constant is 6.53?×?10^?5 cm s^?1, 42 % larger than that of the pristine electrolyte (4.58?×?10^?5 cm s^?1). The cell using electrolyte with 10 mM In³⁺ ions was assembled, and the charge–discharge performance was evaluated, and the average energy efficiency increases by 1.9 % compared with the pristine cell. The improved electrochemical performance may be ascribed to that In³⁺ ions change the hydration state of vanadium ions in electrolyte and promote charge transfer process.     

紫外-可见分光光度法研究十八胺对钙、镁络合滴定的影响

研究了浮选剂十八胺(ODA)对Ca2+, Mg2+离子络合滴定的影响,主要进行了两组对比实验：(1) 滴定前将十八胺固体不过滤,直接进行滴定分析。结果表明这种情况下,十八胺对Ca2+和Mg2+离子的络合滴定都有较大影响,Mg2+离子的滴定终点难以判断,Ca2+离子的滴定终点虽然可以判断,但与不含十八胺的相应空白溶液相比有明显的分析误差。对相关溶液的紫外-可见分光光度分析进一步确认了该实验结果。(2) 滴定前将十八胺不溶物过滤掉,然后进行滴定分析。结果表明这种情况下,十八胺对Ca2+和Mg2+离子络合滴定的影响可以被基本消除。光谱扫描和时间扫描结果显示,滴定前将十八胺过滤后,对于Ca2+和Mg2+两种离子,溶液最大吸收的位置及溶液吸光度的变化情况都与无十八胺的空白溶液接近。     

N-邻羟基苯基马来酰胺酸-改性活性炭对Cu(Ⅲ)的吸附性能

研究了新型吸附剂N-邻羟基苯基马来酰胺酸-活性炭(AC-HPMA)对样品中Cu(Ⅱ)的固相萃取并用电感耦合等离子体-原子发射光谱法(ICP-AES)测定。优化了pH值、吸附剂(AC-HPMA)的用量、流速等条件以达到定量吸附(≥95%),同时考察了共存离子的影响和洗脱剂的洗脱条件。本法测定Cu(Ⅱ)的检出限为0.27μg.L-1,将其应用于茯苓、黄河水、青海湖水中的Cu(Ⅱ)含量的测定,加标回收率在96.3%—99.0%之间;用于测定标准物质中铜离子的含量,结果与标准物参照值一致。     

Online Preconcentration/Determination of Cadmium Using Grape Bagasse in a Flow System Coupled to Thermospray Flame Furnace Atomic Absorption Spectrometry

Abstract

Thermospray flame furnace atomic absorption spectrometry (TS‐FF‐AAS) was employed for Cd(II) determination after online preconcentration. In this system, Cd(II) ions were adsorbed onto a minicolumn packed with grape bagasse. The elution of the metal ions was made with 1 mol L^?1 HCl. Various parameters, such as pH, eluent type, concentration, volume, flow rate for preconcentration, and effect of interfering ions on the retention of the metal ions have been studied. The optimum pH for the adsorption was 3.0. The enrichment factor was 33.7. The limits of detection and quantification for Cd(II) were 0.03 and 0.11 µg L^?1, respectively. The repetitivity and precision were 5.0 (5 minicolumns) and 4.6% (n=18). The stability of the minicolumns was evaluated from successive preconcentration/elution cycles (80 cycles, RSD 3.9%). The proposed method was applied for cadmium determination from certified reference materials, and good agreement was obtained at the 95% confidence level.     

In-situ characterization of electrochromism based on ITO/PEDOT:PSS towards preparation of high performance device

Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)(PEDOT:PSS) is usually sandwiched between indium tin oxide(ITO) and a functional polymer in order to improve the performance of the device. However, because of the strong acidic nature of PEDOT:PSS, the instability of the ITO/PEDOT:PSS interface is also observed. The mechanism of degradation of the device remains is unclear and needs to be further studied. In this article, we investigate the in-situ electrochromism of PEDOT:PSS to disclose the cause of the degradation. X-ray photoelectron spectroscopy(XPS) was used to characterize the PEDOT:PSS films, as well as the PEDOT:PSS plus polyethylene glycol(PEG) films with and without indium ions. The electrochromic devices(ECD) based on PEDOT:PSS and PEG with and without indium ions are carried out by in-situ micro-Raman and laser reflective measurement(LRM). For comparison, ECD based on PEDOT:PSS and PEG films with LiCl, KCl, NaCl or InCl_3 are also investigated by LRM. The results show that PEDOT:PSS is further reduced when negatively biased, and oxidized when positively biased. This could identify that PEDOT:PSS with indium ions from PEDOT:PSS etching ITO will lose dopants when negatively biased. The LRM shows that the device with indium ions has a stronger effect on the reduction property of PEDOT:PSS-PEG film than the device without indium ions. The contrast of the former device is 44%, that of the latter device is about 3%. The LRM also shows that the contrasts of the device based on PEDOT:PSS+PEG with LiCl, KCl, NaCl, InCl_3 are 30%, 27%, 15%, and 18%, respectively.     

Ultraviolet upconversion fluorescence from 6D(J) of Gd3+ induced by 980 nm excitation

Ultraviolet upconversion emissions of 246.2 and 252.8 nm from (6)D(J) levels of Gd(3+) ions were observed in GdF(3): 10% Yb(3+), 0.7% Tm(3+) nanocrystals under 980 nm excitation from a laser diode. The (6)D(J) levels of Gd(3+) ions can be efficiently populated by energy transfer processes of Yb-->Tm-->Gd and Yb-->Gd. A six-photon upconversion process was confirmed by the dependence of 252.8 nm emission intensity on the pumping power. The upconversion mechanism in the six-photon process was discussed based on excited state absorption of Gd(3+) ions, cross relaxation energy transfer between two excited Gd(3+) ions, and energy transfer between Gd(3+) and Yb(3+) or Tm(3+) ions.     

CsI（Tl）+Si-APD探测器的性能测试

介绍了Si-APD的工作原理并对Si-APD中的暗电流进行了理论分析。基于RIBLL上产生的放射性核束流,使用CsI（Tl）+Si-APD探测器对中能重离子进行了能量测试。测试结果显示,CsI（Tl）+Si-APD探测器测量20 MeV/u的重离子时,可得到3%的能量分辨;同时还发现Si-APD中的暗电流大小以及入射粒子的能量大小都会对探测器的能量分辨产生影响。In this paper, the working principle of Si-APD was introduced and the dark current of Si-APD was analyzed theoretically. The intermediate energy heavy ions, which are produced on the RIBLL(Radioactive Ion Beam Line in Lanzhou), were measured with CsI(Tl)+Si-APD detector. The energy resolution of CsI(Tl)+Si-APD detector is about 3% for heavy ions with energy around 20 MeV/u. It is also found that the energy resolution of detector can be in uenced by the dark current of Si-APD and the energy of incident particles.     

Dynamical significance in alkali metasilicate glasses

In this work, we elucidate the effect of the less mobile ions on the dynamics of the more mobile ions by molecular dynamics simulations of lithium ions motion in lithium metasilicate glass by freezing some randomly chosen lithium ions (5%, 10% and 25%) at their initial locations at 700 K. A remarkable slowing down of the dynamics of the majority mobile Li ions was observed both in the self-part of the density–density correlation function, F_s(k,t), and in the diffusion coefficients. On the other hand, there is no significant change in the structure. These results show many similarities to the mixed alkali effect (MAE) with mixing of the small content of foreign alkali (10% and 25% of K₂O), where large reduction of the dynamics was also observed in both experiments and MD simulations. This immobilization of faster ions causes the large MAE as already discussed in relation to the mechanism of the cooperative ion jump motions. Although of lesser importance, the ion dynamics are influenced by the matrix of oxygen atoms, because the jump motions of Li ions are assisted by the localized motions of oxygen atoms.     

液相色谱-离子阱质谱法测定香菇中的核苷酸

采用液相色谱-电喷雾串联质谱法检测香菇中核苷酸。流动相为甲醇和0.1%甲酸溶液,采用梯度洗脱程序,色谱柱为Zorbax XDB-C18（150×2.0mmid,5μm）,流速为0.2mL·min-1。以准分子离子和二级碎片离子对样品中4种核苷酸进行定性和定量,方法的检测限分别为0.500、0.050、0.020、0.010μg/g,相关系数分别为0.9952、0.9967、0.9935、0.9987,相对标准偏差范围为3.25%—9.45%,样品的回收率为78.2%—115.3%。该法快速、灵敏度高、重现性好。