Chromium(III) species is an essential micronutrient, whereas, its hexavalent form, Cr(VI) is considered to be a carcinogen. For the selective detection of Cr(III) in presence of Cr(VI), separation coupled spectroscopic techniques have been often used. For the first time in this work, we report a flow injection analysis coupled dual electrochemical detector (FIA-DECD) for separation-free detection of Chromium (III) and (VI) species. A gold nanoparticles decorated carbon nanofibres-chitosan modified electrode has been prepared by a quick and in-situ electrochemical deposition of Au³⁺ ion in pH 7 phosphate buffer solution (PBS) and has been used as a dual electrochemical detector for Cr(VI)-reduction and Cr(III)-oxidation reactions in pH 2 PBS. Under an optimal hydrodynamic FIA-DECD condition, i.e., at applied potentials 0.1 V (for Cr(VI)-reduction) and 1 V vs Ag/AgCl (for Cr(III)-oxidation) and at a flow rate = 0.8 mL min⁻¹, calculated linear range and detection limit values are; 0.1–100 ppm and 0.69 ppb (0.72 ppt for 20 μL sample loop volume) for Cr(III) and 0.1–100 ppm with detection limit, 0.32 ppb (0.33 ppt for 20 μL) for Cr(VI). No marked interference from other cations and anions like Cu²⁺, Zn²⁺, Cd²⁺, Pb²⁺, Co²⁺, Ca²⁺, Fe²⁺, Mg²⁺, NO₃⁻, NO₂⁻, SO₃²⁻ and SO₄²⁻ were noticed. Selective detection of Cr species (Cr(III) and Cr(VI)) in industrial waste water samples with data comparable to ICP-OES was demonstrated.

铬（III）物种是必不可少的微量营养元素，而其六价形式Cr（VI）被认为是致癌物。为了在存在Cr（VI）时选择性检测Cr（III），经常使用分离耦合光谱技术。在这项工作中，我们首次报告了一种流动注射分析耦合双电化学检测器（FIA-DECD），用于无分离地检测铬（III）和（VI）物质。通过快速原位电化学沉积Au ³⁺制备了金纳米颗粒修饰的碳纳米纤维-壳聚糖修饰电极离子在pH 7磷酸盐缓冲溶液（PBS）中被用作双电化学检测器，用于pH 2 PBS中的Cr（VI）还原和Cr（III）氧化反应。在最佳流体动力学FIA-DECD条件下，即在施加电势0.1 V（用于Cr（VI）还原）和1 V vs Ag / AgCl（用于Cr（III）氧化）和流速= 0.8 mL / min ^-1，计算出的线性范围和检测极限值为：Cr（III）为0.1–100 ppm和0.69 ppb（20μL样品定量管体积为0.72 ppt），检测限为0.1–100 ppm，Cr（VI）为0.32 ppb（20μL为0.33 ppt）。不受其他阳离子和阴离子（如Cu 2 ⁺，Zn 2 ⁺，Cd 2 ⁺，Pb 2 ⁺，Co 2 ⁺，Ca 2 ⁺，Fe）的明显干扰²⁺，镁²⁺，NO ₃ ^-，NO ₂ ^-，SO ₃ ^2-和SO ₄ ^2-中注意到。证明了具有可与ICP-OES相比的数据的工业废水样品中Cr物种（Cr（III）和Cr（VI））的选择性检测。