AsianScientist (Jun. 15, 2016) – Pregnancy and pH test papers have been used for decades. However, there remains challenges to using these absorption-based test papers for detection in fields such as environment monitoring, disease diagnosis and public security.
Generally, for a single color, the eye is more sensitive to the change of color than brightness. Fluorescent colorimetry test papers can visually display the presence of the target compound and its amount—aided by an ultraviolet lamp, anyone may observe the variations of fluorescence brightness and color with the naked eye.
In a study published in Analytical Chemistry, a team led by Professor Zhang Zhongping from the Institute of Intelligent Machines, Hefei Institutes of Physical Science, designed a nanomaterial-based, wide-color-varying fluorescent test paper much like classical pH test paper.
To develop this test paper, the team used modified red quantum dots to obtain super-sensitivity to arsenic(III), or As(III). A small amount of cyan carbon dots with spectral blue-green components were added to produce a composited red fluorescence. The sensory solution was then printed onto a piece of filter paper.
In the presence of As(III), a range of colors is displayed—from red to cyan—clearly detecting a dosage scale as low as 5 parts per billion (ppb). According to World Health Organization’s guidelines, 10 ppb of As(III) in drinking water is considered safe.
The article can be found at: Zhou et al. (2016) Color-Multiplexing-Based Fluorescent Test Paper: Dosage-Sensitive Visualization of Arsenic(III) with Discernable Scale as Low as 5 ppb.
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Source: Chinese Academy of Sciences.
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