2. Institute for Advanced Studies in Basic Sciences
Chemistry Department
Robust and predictive quantitative analysis for mixtures of four dyes through
smartphone spectrometer and neural networks
Fereshteh Matinrad
Mohsen Kompany-Zareh*, Saeed Bagheri, M.Taghi Baharifard
24th Iranian Seminar of Analytical Chemistry
Azarbaijan Shahid Madani University, Tabriz

3. Introduction
Since the introduction of smartphones, hundreds of millions of the devices have been sold. Cellphones in general and smartphones
in particular, are equipped with good megapixel cameras, wifi,
Bluetooth, temperature sensor, light source or LED flashlight etc.
Many research groups across the globe are currently actively engaged in developing or converting the smartphone into an optical sensing tool for different applications.
Smartphones are clearly ubiquitous in the hands of students. These devices have many valuable capabilities that have tremendous potential for use in chemical education.
Smartphone-based pH sensor, AIP ADVANCES, 2015, 5,
Smartphone and Molecular Modeling Fe, CHEMICAL EDUCATION, 2016, 93, 1760. 1

4. Introduction
Optical imaging and sensing techniques based on smartphones have drawn huge attention as they can eliminate the need for bulky and costly optical instrumentation while retaining high sensitivity and image resolution.
Low-cost, portable sensing systems are crucial in resource limited
and remote regions of the world for medical diagnosis, environmental
monitoring and nutrition examination.
Smartphone Spectrometer for colorimetric bio sensing, Analyst, 2016, 141, 2

5. Smartphone Spectrometer
Source: A common desk lamp with incandescent light bulb
Case : Black paper box
Dispersing element: a piece of Compact disc or DVD
Detector and readout: Smart phone 3

6. Materials Crystal violet Amaranth Tartrazine Indigo carmine
(0.5,1, 2,5,10,20,50 ppm)
(0.1, 0.2, 0.5,1,2,5,10,20 ppm)
Tartrazine
Indigo carmine
(1,2,5,10,20,40,50,100,200 ppm)
(0.5,1,2,5,10,20,50 ppm) 4

7. Images obtained through smartphone spectrometer
Amaranth
1 ppm
10 ppm
20 ppm
Crystal violet
0.2 ppm
5 ppm
10 ppm
Indigo carmine
1 ppm
10 ppm
20 ppm
Tartrazine
2 ppm
100 ppm
200 ppm 5

8. Transformation of image to spectrum
Mean 6

9. Transmittance spectra of different Dyes
Amaranth
Crystal violet
Indigo carmine
Tartrazine 7

10. Experimental design Violet Tar Indig Amrt Violet Tar Indig Amrt 1 2 32 3
0.2
0.5 5 4 10 6 20 7 8 9 11 40 12 13 14
Violet
Tar
Indig
Amrt 15 10 16
0.1 17 2 20 18 1
0.5 19 21 5 22 23 24 25
0.2 26 40 27 28

11. Transmittance spectra of dye mixtures9

12. PLS Calibration for Smartphone Spectrometer data
Poor performance in prediction of test set due to the non-linear relation of transmittance to concentration 10

13. PLS calibration for Commercial Spectrometer data
High prediction performance in test set through PLS calibration of spectra of commercial spectrometer as a reference data and method
Results show that dye solutions made properly 11

14. RBFN (Radial Basis Function network)
ℎ 𝑗 𝑥 =𝑒𝑥𝑝 − 𝑥− 𝑐 𝑗 𝑟 𝑗 2
𝑄 2 =1− 𝑖=1 𝑛 𝐸𝑋𝑇 𝑦 𝑖 − 𝑦 𝑖 𝑛 𝐸𝑋𝑇 𝑗=1 𝑛 𝑇𝑅 𝑦 𝑗 − 𝑦 𝑇𝑅 𝑛 𝑇𝑅
Local modeling radial basis function networks. Chemometrics and Intelligent Laboratory Systems, 2000, 50, 179. 12

15. Calibration with RBFN Q2 Sigma Center
High performance in prediction of test set
Dye Q2
Sigma
Center
Crystal violet
0.97
625 18
Tartrazine
660 14
Indigo carmine
0.99
670
Amaranth
0.94
685 13 13

16. Thanks
Any Question?

17. Diffraction Grating
we considered to use digital versatile disks (DVDs) as monochromator. Spacing between the recording tracks in DVDs are 0.74 µm, making a grating of about 1350 lines/mm, which it is comparable to the gratings in spectrophotometers routinely used in laboratories ( 300 – 2400 lines/mm ) .
A DVD Spectroscope, Journal of Chemical Education, 2006, 83, 56.

18. Absorbance spectra obtained by the smartphone spectrometer
Indigo carmine
Zoom

19. Measurement of solution’s pH
Tartrazine
mg/l pH
200
7.79
100
7.73 50
7.76 10
7.85 5
7.88
Crystal violet
mg/l pH 20
6.89 10
6.84 5
6.75 2
6.69 1
6.63
Indigo carmine pH 50
7.51 20
7.47 10
7.56 5
7.42
Amaranth
mg/l pH 50
7.12 20
7.23 10
7.19 5
7.14