建立了测定食品中Cu 的二元双波长可见吸收光谱(DWO-VIS)法。在pH 6.86 的Tris-盐酸缓冲介质中，丽春红S 与Cu(Ⅱ)发生反应，在可见光区生成具有一个明显正吸收峰和一个明显负吸收峰的离子缔合物。最大正吸收波长和最大负吸收波长分别为445 nm和510 nm。Cu(Ⅱ) 在0.06～1.6 mg/L（正吸收，445 nm）、0.04～1.6 mg/L（负吸收，510 nm）和 0.03～1.6 mg/L（DWO-VIS ，445 nm + 510 nm）范围内遵从朗伯-比尔定律，表观摩尔吸光系数（κ）分别为 8.70×103（正吸收法）、2.04×104(负吸收法) 和 2.92×104（DWO-VIS法）L/(mol·cm)，定量限分别为 0.62、0.38 和0.26 mg/100 g。还探讨了吸收光谱特征、适宜反应条件及共存物质的影响。双波长法用于饼干、面条及奶粉中Cu 的测定，加标回收率为97.9%～102%，相对标准偏差RSD（n=5）为2.5%～2.8%。

A new dual-wavelength visible absorption spectroscopy method (DWO-VIS) for quantifying copper in food was established. In tris-hydrochloric acid buffer medium of pH 6.86, ponceau S reacted with copper(Ⅱ) to form an ion association complex with obvious a positive absorption peak and a negative absorption peak in visible area. The maximum positive absorption wavelength and the maximum negative absorption wavelength were located at 445 nm and 510 nm respectively. copper(Ⅱ) obeys Lombard Beer’s law in definite mass concentration range of 0.06 - 1.6 mg/L（positive absorption，445 nm） and 0.04 - 1.6 mg/L（negative absorption，510 nm）and 0.03 - 1.6 mg/L（DWO-VIS ，445 nm + 510 nm） respectively. Their apparent molar absorptivity (κ) were 8.70×103（positive absorption method） and 2.04×104(negative absorption method) and 2.92×104（DWO-VIS method）L/(mol·cm) respectively with the limit of quantitation were 0.62,0.38 and 0.26 mg/100 grespectively. The absorption spectral characteristic and optimum reaction conditions and effect of the coexistence material were studied. The dual-wavelength visible absorption spectroscopy method was applied to determine the content of copper in biscuits and noodles and milk powder with spiked recoveries and relative standard deviation (RSD) (n=5) found were in the ranges of 97.9% - 102% and 2.5% - 2.8% respectively.