ISBN : 978-602-17761-4-8
53
Proceedings of 2
nd
REPTech Crowne Plaza Hotel, Bandung, November 15-17, 2016
© 2016 Published by Center for Pulp and Paper through 2
nd
REPTech
In the luorescence detection, also referred to as quantitative detection by applying luorescence spectroscopy F-4500, Hitachi, Japan, the surface luorescence intensity of the paper-based sensor
was measured. The excitation and emission wavelengths were 490 nm and 567 nm, respectively. As anthraquinone derivative was quenched by Cu
2+
in solution, the surface luorescence intensity of paper- based sensors immersed in Cu
2+
solutions of various concentrations was determined. Paper-based sensors, fabricated using a 1 gL anthraquinone derivative acetone solution, were
immersed in 5-mL Cu
2+
solutions with concentrations of 1, 2, 3, 4, 5, and 6 ppm for 10 min. Additionally, to achieve higher sensitivity, paper-based sensors were fabricated using an anthraquinone derivative
acetone solution of lower concentration 0.4 gL. Subsequently, these fabricated sensors were immersed in 5-mL Cu
2+
solutions with concentrations of 200, 400, 600, and 800 ppb for 10 min. After immersion, excess water was removed with a paper wiper. Before drying, the surface luorescence intensity of the
paper-based sensors was measured, and the relationship between surface luorescence intensity and Cu
2+
concentration was determined. All aqueous samples in this research were adjusted to pH 7 using a buffer solution containing
4-2-hydroxyethyl-1-piperazineethanesulfonic acid HEPES and NaOH, which is widely used in research related to heavy metal solutions.
2.5 Interference
To determine the selectivity of the paper-based sensor, interference by other metal ions was studied in both visible and luorescence detections. Na
+
, K
+
, Ca
2+
, Fe
3+
, Co
2+
, Cd
2+
, Mn
2+
, Hg
2+
, Pb
2+
, Ni
2+
, Zn
2+
, and Ag
+
were tested. The paper-based sensors were immersed in a 5-mL 20-ppm aqueous solution of each metal ion. After 10 min immersion, the color of the sensor was observed by the naked eye and captured
using a digital camera. In luorescence detection, excess water on the paper-based sensors was removed and surface luorescence intensity was measured.
Results and Discussion 3.1 Fabrication and Characterization
A quick and easy fabrication method was developed using inkjet printing technology. The anthraquinone derivative was irmly adsorbed on cellulose iber surfaces through non-covalent bonds,
including hydrogen bonds, hydrophobic forces, and CH–π interactions.
16
The fabrication method developed in this research has the following advantages: i although acetone evaporated quickly, perhaps causing anthraquinone derivative to block the nozzle of the printer head,
the ink easily lowed in the nozzle, redissolving anthraquinone derivative and preventing the printer head nozzle from being blocked; ii acetone is non-destructive to the ilter paper iber network; and iii
inkjet printing technology makes lexible pattern design and homogeneous distribution of anthraquinone derivative possible. Furthermore, as shown in Fig. 1, anthraquinone derivative is only concentrated in
the top layer with a total thickness of 150 μm, suggesting that it was possible to easily control and reduce
the amount of anthraquinone derivative, and accelerate and accentuate the color reaction, compared with other fabrication methods, such as immersion.
Fig. 2 shows a CLSM image of the anthraquinone derivative distributed evenly on cellulose ibers by inkjet printing. Even distribution was important for detection, especially for luorescence detection,
and dificult to achieve using any other method. Consequently, inkjet printing appeared to be an ideal method for this fabrication regarding pattern design, operation, and cost.
3.2 Qualitative and Quantitative Detection
