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| Study on Dual-wavelength Photometric Method for Ultra Micro Liquid Volume Measurement |
| WANG Jin-tao1,CHEN Chou-yun1,2,LI Zhi-hao1,TONG Lin1, LIU Zi-yong1,ZHANG Long1,LUO Zhi-dong3 |
1.National Institute of Metrology, Beijing 100029, China;
2.China Jiliang University, Hangzhou, Zhejiang 310018, China;
3.Guizhou Institute of Metrology, Guiyang, Guizhou 550003, China |
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Abstract In order to overcome the shortcoming of significant influence of evaporation capacity on hydro-weighting method, a dual-wavelength photometric method based on Lambert-Beer law at 520 nm and 730 nm was introduced. Micro liquid volume to be measured can be calculated through the linear relation between dilute solution concentration and absorbance. Comparing with the gravimetric method, experimental systems for dual-wavelength photometric method is designed. The test data at 1 μL and 5 μL indicates that dual-wavelength photometric method is in good conformance with gravimetric method, and meet the technical requirement of ISO 8655, but the measured value of dual-wavelength photometric method is a little bigger. dual-wavelength photometric method is able to provide a good solution for micro liquid volume measurement. By comparing with gravimetric method, dual-wavelength photometric method is low in requirement of measurement environment, and easy to realize the online calibration and capable of effectively reducing the influence of liquid evaporation.
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2015, Vol. 36 
