Full
Outline
To establish a method for rapid detection of iron content in tap water and food samples by paper-based microfluidic chip.
The paper-based chips were cut out using an embossing gadget. And the paper chip was prepared by soaking. Samples to be tested could be dropped onto the prepared chips directly. When the chip showed a stable color based on O-dinitrogen colorimetric method, the chip could be placed on a self-made platform for taking photo. Then the gray value of the picture could be read and the iron concentration could be acquired. The study selected the type of filter paper, and optimized the concentrations of 1,10-phenanthroline and hydroxylamine hydrochloride during soaking, as well as the soaking time and coloring time.
Whatman 3#filter paper was selected to prepare the paper chip. And the cut paper chip was soaked in acetate buffer solution containing 8.00 g/L of 1,10-phenoroline and 50.00 g/L of hydroxylamine hydrochloride (pH=4.50) for 3 minutes.After the sample was dropped onto the paper chip for 15 minutes, photos could be taken for detection. When the concentration of Fe3+ in sample solution was 5.00×10–3 mmol/L to 7.00 mmol/L, it had a good linear relationship between the gray value and the concentration. The limit of detection the paper chip method was 0.004 mmol/L. When the 13 kinds of interfering metal ions, including 1 mg/L Cd2+, Cu2+ and the like, were coexisting in the sample solution, they did not affect the detection of Fe3+. The adding standard recoveries were 86.0% to 114.7%. The relative standard deviations of the same sample 6 test results within the same day were 1.7% to 7.5%. And the relative standard deviations of 6 consecutive days detection results were 3.4% to 7.9%. The prepared paper chip could be stored for at least for 3 months under the condition of avoiding light at 4 ℃. When the actual samples were detected,the relative deviation between the paper chip method and the flame atomic absorption method was less than or equal to 2.404%.
The iron detection method based on paper-based chips established in this research is simple to operate, accurate and reliable, which can be a strong support for on-site rapid detection of iron content in food detection field.
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| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |
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