高效液相色谱-电感耦合等离子体质谱联用测定化妆品中六价铬与三价铬

建立了一种有效分离检测化妆品中Cr(Ⅵ)和Cr(Ⅲ)的高效液相色谱-电感耦合等离子体质谱(HPLC-ICP-MS)分析方法。以10 mmol/L(pH 7.0)EDTA为提取溶剂,0.075 mol/L硝酸(pH 7.0,氨水调节)为流动相,采用Agilent Bio-WAX柱(4.6 mm×50 mm,5μm)对样品提取液进行分离,电感耦合等离子体质谱进行测定。在优化实验条件下,Cr(Ⅵ)和Cr(Ⅲ)在0～100μg/L范围内线性关系良好,相关系数(r~2)均为0.999 9。Cr(Ⅵ)和Cr(Ⅲ)的检出限分别为6、2μg/kg,定量下限分别为18、6μg/kg,加标回收率为85.1%～113%,相对标准偏差为0.4%～4.6%。实际样品的测定结果显示,在膏霜乳液类及粉类样品中检出Cr(Ⅵ)和Cr(Ⅲ)。该方法重现性好、灵敏度高,且Cr(Ⅵ)在中性条件下较稳定,不易转化为Cr(Ⅲ),适用于不同基质类型化妆品中Cr(Ⅵ)和Cr(Ⅲ)的同时检测。     

SPE–ICP–AES法测定环境水样中Cr(Ⅲ)

建立固相萃取与电感耦合等离子体原子发射光谱法(ICP–AES)测定环境水样中Cr(Ⅲ)含量的方法。合成了功能化铁氧体磁性材料作为固相萃取剂,优化了固相萃取条件。当样品溶液的p H值为2.5时,固相萃取剂能在5 min内完成Cr(Ⅲ)的富集。使用1 mol/L HNO3在3 min内即可解吸附分离Cr(Ⅲ),饱和吸附容量为15.2μg/mg,研究了共存离子的影响。Cr(Ⅲ)含量在1~50μg/L范围内与发射光谱强度呈良好的线性关系,线性相关系数为0.999 9,检出限为0.09μg/L,测定结果的相对标准偏差为2.2%(n=8),回收率为97.7%~104.8%。该方法高效、快速,测定结果准确可靠,可用于测定环境水样品中的痕量Cr(Ⅲ)。     

聚(苯乙烯-二乙烯基苯)反相高效液相色谱填料在胸腺素α1分离中的应用

采用高聚物型苯乙烯-二乙烯基苯(PS-DVB)麦科菲反相高效液相色谱柱(MKF-RP-MH)分离胸腺素α1,优化色谱条件为:流动相A:0.01 mol/L磷酸盐缓冲液(pH 7.0或8.0),流动相B:乙腈,梯度洗脱条件0~20 min,0%~10%乙腈,20~40 min,10%~30%乙腈;温度:30℃;流速:0.8 mL/min;检测波长:214 nm。在优化条件下分离了胸腺素α1标准品和样品。样品浓度在0.05~4 g/L时,线性方程为C=0.0099A-0.0798(r=0.9994),胸腺素α1最大载样量为120μg(6 g/L)。     

高效阴离子色谱法测定电催化氮气氧化中NO3-/NO2-的含量

开发了一种测定高浓度SO42-电解液(0.5 mol/L)中NO3-/NO2-含量的高效阴离子色谱法.该方法不受催化剂溶出以及其它干扰离子的影响,可以应用于电催化氮气氧化制备NO3-/NO2-.通过改变流动相的流速、淋洗液浓度以及柱温实现了SO42-与NO3-/NO2-色谱峰的完全分离.优化得到最佳检测条件:流动相流速...     

液相色谱-串联质谱测定面条和米粉中的硫脲

建立了米面制品中硫脲的液相色谱-串联质谱(LC-MS/MS)测定方法.实验优化了样品提取方法、液相色谱条件和质谱参数.样品用80%乙醇超声波提取,离子交换色谱分离,色谱柱为NUCLEOSIL 100-5SA 阳离子交换柱,流动相为乙腈-(1%乙酸+0.2%乙酸铵)水溶液(30: 70),流速0.5mL/min.采用电喷雾质谱正离子模式电离,多反应选择离子检测,检测离子对为m/z 77/60和m/z 77/43,其中m/z 77/60为定量离子对.结果表明: 本方法简便快速、准确可靠,相对标准偏差＜4.0%;回收率为83%～90%;检出限为0.5 mg/kg;定量下限为 5 mg/kg.     

离子色谱柱切换在线前处理法同时测定皮革及织物中的三价铬与六价铬离子

采用一根NG1反相色谱柱作为前处理柱在线去除样品中的水溶性有机基质,建立了离子色谱柱切换技术同时测定CrⅢ与CrⅥ的方法。进样前,先将待测样品水溶液与一定浓度的乙二胺四乙酸(EDTA)溶液充分反应,使其中的CrⅢ络合生成阴离子产物,该阴离子产物在可见光范围内有较强吸收;进样后,样品中的离子经前处理柱分离后被收集在2 mL接收环内,通过柱切换技术,淋洗液将接收环内的离子带至阴离子分析柱中分离,CrⅥ与1,5-二苯卡巴肼(DPC)溶液进行衍生化反应后与CrⅢ的EDTA络合物在同一波长下有较强吸收,由此可完成对两种离子的同波长测定。在优化的实验条件下,CrⅢ与CrⅥ的线性范围分别为0.3~10 mg/L(r=0.9991),0.05~2 mg/L(r=0.9992),检出限分别为80.78和6.67μg/L(信噪比S/N=3),将3 mg/L CrⅢ与0.3 mg/L CrⅥ标准溶液连续进样6次,得到的色谱保留时间及峰面积相对标准偏差均小于3%;将本方法应用于皮革中CrⅢ与CrⅥ的检测,加标回收率为88.7%~108.5%。实验结果表明,本方法用于皮革及织物中铬离子的检测,具有快速、灵敏、选择性好等优点。     

反相萃取层析与光度法联用分离/测定中草药中微量铁的研究

研究了硅藻土-TBP反相萃取层析-分光光度法分离和测定微量铁的新方法.以0.30mol/L盐酸做流动相,以负载有磷酸三丁酯(TBP)的硅烷化白色担体为固定相,反相萃取层析法分离微量Fe(Ⅲ)与Co(Ⅲ)、Ge(Ⅳ)、Al(Ⅲ)、Cr(Ⅲ)、Mn(Ⅱ)、Ni(Ⅱ)等.在4.0mol/L盐酸介质中,铁与多种金属离子都被萃取在TBP柱上.用2mol/L盐酸洗脱部分离子,用0.30mol/L盐酸可定量地洗脱铁,然后用0.010mol/L盐酸可将柱上的其它离子洗脱.洗脱液中的铁用分光光度法测定.此方法可将铁与绝大部分干扰离子分离,并用于中草药中微量铁的分离和测定.     

离子交换色谱分离-紫外检测法测定吡啶离子液体阳离子

建立了用离子交换色谱分离-紫外检测法测定N-乙基吡啶、N-丁基吡啶和N-丁基四甲基吡啶3种吡啶离子液体阳离子的方法。采用磺酸型阳离子交换柱,以乙二胺-柠檬酸-乙腈为流动相,研究了流动相和色谱柱温度对离子保留行为的影响和规律。实验发现,吡啶阳离子的保留过程是放热过程。优化后的色谱条件:流动相为乙二胺(0.2 mmol//L)-柠檬酸(0.3 mmol//L)-乙腈(0.5%,v/v,pH=4.2),流动相流速为1.0mL/min,色谱柱为Shim-pack IC-C1阳离子交换柱,色谱柱温度为30℃。在此条件下3种吡啶阳离子可以达到基线分离。所测阳离子的检出限(S/N=3)分别为0.01、0.01、0.02mg/L,峰面积的相对标准偏差(n=5)小于0.8%。紫外检测法测定化学实验室合成的吡啶离子液体样品,样品加标后测得的加标回收率在96.3%~104%。方法准确、可靠、快速,具有较好的实用价值。     

石墨炉原子吸收光谱法测定土壤中可交换态Cr(Ⅲ)和Cr(Ⅵ)

提出了流动注射离子交换石墨炉原子吸收光谱法测定土壤中可交换态Cr(Ⅲ）和Cr(Ⅵ）的分析方法，优化了提取方法、分离富集条件和流路参数等。分析速度为20样/h，Cr(Ⅲ）和Cr(Ⅵ）的检出限（3σ）分别为24pg和4.0pg，相对标准偏差（n=10)分别为4.7%和5.9%。     

离子色谱-紫外检测法同时分析碘酸根、碘离子、溴酸根和溴离子

建立了同时分析碘酸根、碘离子、溴酸根和溴离子的离子色谱-紫外检测分析方法。用季铵型阴离子交换柱,以柠檬酸-乙腈为流动相,采用紫外检测器实现了4种离子的同时分离和检测。研究了检测波长和流动相种类、浓度、pH值等因素对4种离子分离和测定的影响,探讨了保留规律,优化了色谱分析条件。在检测波长为210 nm、流动相为1.0 mmol/L柠檬酸-乙腈（85：15,v/v;pH 5.0）、流速为0.9 mL/min、柱温为40 ℃条件下,4种离子完全分离,且系统峰不干扰测定。4种离子的检出限（S/N=3）为0.07~0.16 mg/L,连续5次进样测定的峰面积和保留时间的相对标准偏差均在1%以下。将此方法用于离子液体样品及地下水样品的分析,结果准确、可靠。     

Determination of chromium(III) and total chromium using dual channels on glass chip with chemiluminescence detection

A simple, rapid and sensitive method for the determination of chromium(III) and total chromium using the simple dual T channels on glass chip with negative pressure pumping system and chemiluminescence (CL) detection is presented. The CL reaction was based on luminol oxidation by hydrogen peroxide in basic aqueous solution catalyzed by chromium(III). Total chromium in form of chromium(III) was achieved after chromium(VI) was completely reduced by acidic sodium hydrogen sulfite. Total chromium could then be determined with the same strategy as the chromium(III). The CL reagent was composed of 1.0 × 10⁻⁴ mol/L luminol, 1.0 × 10⁻² mol/L hydrogen peroxide and 0.10 mol/L sodium bromide in 0.050 mol/L carbonate buffer (pH 11.00). The 1.0 × 10⁻² mol/L ethylenediaminetetraacetic acid was added into the sample solution in order to improve the selectivity. Chromium(III) could be detected at a notably concentration of 1.6 × 10⁻¹⁶ mol/L and a linear calibration curve was obtained from 1.0 × 10⁻¹⁵ to 1.0 × 10⁻¹³ mol/L. The sample and CL reagent consumption were only 15 and 20 μL, respectively. The analysis time was less than 1 min per sample with the precision (%R.S.D.) was 4.7%. The proposed method has been applied successfully to the analysis of river water, mineral waters, drinking waters and tap water. Its performance was verified by the analysis of certified total chromium-reference materials and by recovery measurement on spiked synthetic seawater sample.     

Ion-pair chromatographic determination of chromium(VI)

Ion-pair chromatography (IPC) with conductometric detection was investigated as a precise and selective analytical method for the determination of chromium in electro-plating solutions and waste waters. Chromatographic parameters were optimized for separation of Cr(VI) and SO(2-)(4). The analytical column (100 x 6 mm) was packed with 10 mum silasorb C(18) (Czechoslovakia). Tetrabutylammonium butyrate (TBAB), at pH 7.0 in acetonitrile-water (18:82 v/v) mixture, was used as the eluent. Two samples of solution are taken for the analysis. In the first of them the amount of Cr(VI) is determined, in the second one Cr(III) is oxidized to Cr(VI) with H(2)O(2) in alkaline medium and the total amount of Cr is determined. From the difference of the two obtained results the concentration of Cr(III) is calculated. The detection limit of Cr(VI) is 0.1 mug/ml and the relative standard deviation (at the 1.0 mug/ml) is 4.0%. The IPC results for chromium agreed closely with these obtained by spectrophotometry.     

Underpotential Deposition Study and Determination of Bismuth on Gold Electrode by Using Voltammetry

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Speciation of chromium by selective separation and preconcentration of Cr(III) on an immobilized nanometer titanium dioxide microcolumn

Nanometer titanium dioxide immobilized on silica gel (immobilized nanometer-scale TiO2 particles) was prepared by a sol-gel method and characterized by X-ray diffraction and scanning electron microscopy. The adsorptive behavior of Cr(III) and Cr(VI) on immobilized nanometer TiO2 was assessed. Cr(III) was selectively sorbed on immobilized nanometer TiO2 in the pH range of 7-9, while Cr(VI) was found to remain in solution. A sensitive and selective method has been developed for the speciation of chromium in water samples using an immobilized nanometer TiO2 microcolumn and inductively coupled plasma atomic emission spectrometry. Under optimized conditions (pH 7.0, flow rate 2.0 mL/min), Cr(III) was retained on the column, then eluted with 0.5 mol/L HNO3 and determined by ICP-AES. Total chromium was determined after the reduction of Cr(VI) to Cr(III) by ascorbic acid. The adsorption capacity of immobilized nanometer TiO2 for Cr(III) was found to be 7.04 mg/g. The detection limit for Cr(III) was 0.22 ng/mL and the RSD was 3.5% (n = 11, c = 100 ng/ mL) with an enrichment factor of 50. The proposed method has been applied to the speciation of chromium in water samples with satisfactory results.     

Two-Phase Aqueous Extraction of Chromium and its Application to Speciation Analysis of Chromium in Plasma

 This work proposes a new extraction method for chromium based on the two-phase aqueous system isopropyl alcohol-ammonium sulfate-ammonium thiocyanate (i-PrOH-(NH₄)₂SO₄-NH₄SCN), and the related experimental conditions are optimized. The results show that chromium (III) can be quantitatively extracted under the selected conditions: 4 mL of i-PrOH, 200 μL of 2 mol/L sulfuric acid, 1 mL of 4 mol/L NH₄SCN and 3 mL of saturated (NH₄)₂SO₄ solution (V_total=10 mL). Application of the proposed method to speciation analysis of plasma chromium was also investigated and satisfactory results were obtained. Received May 22, 1999. Revision November 8, 1999.     

Preconcentration of chromium(III) and speciation of chromium by electrothermal atomic absorption spectrometry using cellulose adsorbent

A simple and sensitive method has been developed for species selective determination of chromium(III) and chromium(VI) in water by electrothermal atomic absorption spectrometry. The procedure is based on selective absorption of Cr(III) on a cellulose micro column (pH 11, 0.5 mol L(-1) NaCl). Total chromium was subsequently determined after appropriate reduction of Cr(VI) to Cr(III). Recoveries of more than 97% were found. A concentration factor of 100 was achieved. The relative standard deviations (n=10) at the 40 ng L(-1) level for chromium(III) and chromium(VI) were 2.3% and 1.8% and corresponding limits of detection (based on 36) were 1.8 ng L(-1) and 5.1 ng L(-1), respectively. No interference effects have been observed from other investigated species and the method has been successfully applied to natural water samples.     

Simultaneous speciation of inorganic chromium(III) and chromium(VI) by hollow‐fiber‐based liquid‐phase microextraction coupled with HPLC–UV

The speciation of chromium(VI) and chromium(III) was investigated by using hollow fiber liquid‐phase microextraction based on two immiscible organic solvents followed by high performance liquid chromatography with ultraviolet detection. In this method, chromium(VI) and chromium(III) reacted with ammonium pyrrolidine dithiocarbamate to produce hydrophobic complexes. Subsequently, the complexes were first extracted into a thin layer of organic solvent (n‐dodecane) present in the pores of a porous hollow fiber, and then into a μL volume of an organic acceptor (methanol) located inside the lumen of the hollow fiber. Then, the extracting organic phase was injected into the separation column of the high‐performance liquid chromatograph for the analysis of both chromium species. Effective parameters on extraction were optimized using one‐variable‐at‐a‐time method and central composite design. Under optimized conditions, a linear range of 0.25–100 and 0.5–100 μg/L (R ² > 0.998), the limits of detection of (S/N = 3) 0.08 and 0.1 μg/L and a preconcentration factor of 625 and 556 were achieved for chromium(VI) and chromium(III), respectively. The method was successfully applied to the speciation and determination of chromium species in different water samples and satisfactory results were obtained.     

非抑制电导检测离子色谱法测定硅藻培养液中硅酸根

采用戴安阴离子AS23(4 mm×250 mm)分析柱和AG23(4 mm×50 mm)保护柱、恒温电导检测器,建立了测定硅藻培养液中硅酸根(SiO2-3)含量的非抑制电导检测离子色谱法。以4 mmol/L碳酸钠为淋洗液,淋洗液流速1.0 mL/min,进样体积100 μL,采用峰高定量。该法测定SiO2-3的线性范围为0~40 mg/L,检出限为0.017 mg/L,重复测定同一标样的相对标准偏差( RSD,n=7 ) 小于5%,峰面积和峰高的RSD分别为10.9%、4.8%。测定不同生长时期硅藻培养液中的SiO2-3,样品的加标回收率为102%~120%。该法灵敏、准确、简便易行,适用于硅藻培养液中SiO2-3的检测。     

On-line liquid chromatography/thermospray mass spectrometry in the analysis of oligosaccharides.

The analysis of intact neutral oligosaccharides by on-line liquid chromatography/thermospray mass spectrometry is described. Molecular-weight information on oligomers up to a degree of polymerization of 10 is obtained using an aqueous mobile phase containing 10(-4) mol/L sodium acetate, which was found to be compatible with thermospray interfacing and ionization. Ions due to sodiated and disodiated oligosaccharides are observed under these conditions without fragmentation. The aqueous 10(-4) mol/L sodium acetate mobile phase is demonstrated to be applicable in the separation of mixtures of oligosaccharides on a reversed-phase octadecyl-modified silica column.     

Determination of Chromium(III) with Eriochrome Cyanine R by Fourth-Derivative Spectrophotometry

Summary

A fourth-derivative spectrophotometric determination of chromium(III) with Eriochrome Cyanine R (ECR) was described. The method was based on measuring the fourth-derivative value (D₄) at 545 nm. The experimental and instrumental variables (wavelength range, scan speed, band width and order of derivative) were optimized. Under the optimum conditions, the calibration graph fit the equation d⁴ A/d⁴ = 3.75 × 10⁵ [Cr(III)] + 0.003 (r=0.9991) and have a relative standard deviation of 1.19%. The method was valid for concentrations between 20 ng/ml and 80 ng/ml of chromium(III). The molar ratio of the formed complex was 1:2 (M:L). The proposed method was successfully applied to the determination of chromium in steel.