Selectivity of Formaldehyde Sensor Conclusion

Proceedings of MatricesFor IITTEP – ICoMaNSEd 2015 ISBN: 978-602-74204-0-3 Keynote Invited Papers Page 25 To obtain an optimum condition on formaldehyde sensor, the pH of buffer solution is varied at pH 1.0 – 8.0. The calibration curve for formaldehyde standard solution at different pH is presented in Figure 7. It is seen that the buffer condition influenced the sensor sensitivity, where the optimum condition is obtained at pH 3.0. The sensor give a relative high sensitivity at low pH pH 1.0-5.0 and consistently decrease the sensitivity at high pH condition pH 6.0 – 8.0. However, the detection linearity is not influenced by the pH condition. Therefore, all measurement is carried out at pH 3.0.

13. Selectivity of Formaldehyde Sensor

The selectivity of formaldehyde sensor has been examine for formaldehyde in the absence and in the presence of suspected interfering agents. Interferents 2.0 ppm, which are commonly found in food samples are added in to 2.0 ppm formaldehyde standard solution. The single and mixture analytes are determined by using formaldehyde sensor, and the response sensitivity is summarised in Figure 8. The results showed that every single interfering agents give small response in UV-vis spectrophotometer. At high concentration of interfereing agents are also reduce 4-5 the responses formaldehyde standard solution. However, the sensor is free from interferent when the concentration of interfering agents are low 2 ppm. Ascorbic acid is the most potential interfering agent. Figur 8. Response selectivity of a sensor into formaldehyde and interference. Single interfering agents 5.0 ppm and their mixture with 2.0 ppm formaldehyde standard solution is analysed in UV-vis spectrophotometer at λ 560 nm. Experimental parameter is the same as in Figure 6.

14. Conclusion

The electrodeposited polymer has been demonstrated to be compatible in the production of reprooducible sensor. The application of electrodeposited polymer film as a very good matrix polymer for immobilization of active materials which are suited for the construction of biosensor and chemical sensors. An uric acid biosensor in electrochemical detection system is the example of reproducible biosensor which is developed by using deposited polytyramine. The uric acid biosensor showed a sensitive response to uric acid with a linear calibration curve lies in the concentration range of 0.1 – 2.5 mM, slope 0.066 µAmM, and the limit detection was 0.05 mM uric acid SN=3. Another example of sensor is formaldehyde sensor that is developed by immobilization of chromatophic acid onto a conducting transparent plastic and interfaced in UV-Vis spectrophotometer detection system. 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Situmorang, M., Simanjuntak, E.P., and Silaen, D., 2010, Pengembangan Metode Analisis Spektrofotometry Melalui Reaksi Enzimasi Untuk Penentuan Glukosa Di Dalam Buah-Buahan, Jurnal Sain Indonesia 343: 8-14. [32]. Sinaga, M., Sihombing, K., and Situmorang, M., 2014, Rancang Bangun Sensor Kimia Sebagai Instrumen Analisis Dalam Deteksi Spektrofotometri Untuk Penentuan Pengawet Formaldehida dan Nitrit, Research Report, UNIMED, Medan. Proceedings of MatricesFor IITTEP – ICoMaNSEd 2015 ISBN: 978-602-74204-0-3 Keynote Invited Papers Page 29 ENHANCING STUDENTS’ HIGHER ORDER THINKING SKILLS THROUGH SCIENCE EDUCATION Liliasari 1 1 Department of Science Education, Faculty of Mathematics and Science Education, Indonesia University of Education, Bandung, Indonesia liliasariupi.edu Abstract To face against the 21 st century challenges Indonesian people have to develop their higher order thinking skills. The development of the skills could be done through science education. The science knowledge as vehicle of thought was needed to solve Indonesian people’ problems in their life.It will make them survive and contribute to overcome the world crisis. There are many models of teaching science based on the educational level, from integrated models in primary education, to combined in junior high schools and separated models in high schools up to universities. In the science teacher training institutions the variation of teaching science was also appropriate in- line with teachers’ requirement at schools. Thinking science conducted through students’ generic science skills development and comprehension of multimodal representation of science subjects. Besides the difficulty of subject matter mastery there are also gaps in information spreading in the remote society that should be attack through information communication technology ICT. Keywords : science education, higher order thinking skills, generic science skills

1. Introduction