2

Rapid Determination of Sunset Yellow in Soft Drinks

using Silicon Nanoparticles Synthesized under Mild

Conditions

Fu-Xia Yang*, Xiao-Tong Ma*† and Shun-Yu Han*†

* Gansu Key Laboratory of Viticulture and Enology, College of Food Science and

Engineering, Gansu Agricultural University, Lanzhou 730070, China.

† To whom correspondence should be addressed.

E-mail: maxiaotong17@163.com, lzhansy@126.com

Analytical SciencesAdvance Publication by J-STAGEReceived April 20, 2021; Accepted June 21, 2021; Published online on July 2, 2021DOI: 10.2116/analsci.21P140

3

Abstract

Sunset yellow (SY) is a synthetic colorant which can cause allergies, diarrhea and other

symptoms in sensitive people. When ingested too much, it can accumulate in the body

and cause damage to the kidneys and liver. Therefore, the content of SY in food must be

strictly controlled. In order to regulate their use and ensure food quality, simple and

cost-effective methods need to be developed to identify them. In this experiment,

fluorescent silicon nanoparticles (SiNPs) were prepared by a one-step method, which is

simple, mild and less time-consuming. The fluorescent SiNPs prepared had good

thermal stability, excellent salt resistance and pH stability. SY effectively quenched the

fluorescence of SiNPs by fluorescence resonance energy transfer when added to the

system as an interfering substance. The method had a good linear relationship in the

range of SY concentration of 0.050 ~ 14.0 μg mL-1 and the detection limit is 0.023 μg

mL-1. The established sensor was applied to the detection of SY in beverages, and the

recovery rate was 93.8% ~ 102.4%. Based on the excellent selectivity and sensitivity of

the method, it could provide a convenient way for the detection of SY in food samples.

Keywords：Sunset yellow. food quality. Silicon nanoparticles. Fluorescence.

4

Introduction

Food pigment is a kind of food additive, including natural pigments and synthetic

pigments. Compared with natural pigments, synthetic pigments have the advantages of

stable properties, strong coloring power and low price, so they have been widely used in

the food processing industry1,2. The addition of synthetic pigments to food and

beverages can not only improve the appearance and quality, but also maintain the

natural color of food and beverages. However, synthetic pigments have some potential

hazards to human health. Excessive consumption of synthetic pigments have been

reported to cause symptoms such as allergy, asthma, eczema, diarrhea, and liver cancer

in mice, as well as liver injury and kidney failure in humans3,4. Sunset yellow is one of

the common synthetic pigments used in the food processing industry. The Food Safety

Administration of some countries stipulates a daily intake of 4 mg kg-1 per person and

even some countries such as Finland and Sweden prohibit the use of sunset yellow5.

Therefore, in order to control food safety and ensure consumer’s safety, it is of great

significance to quantitatively determine the content of sunset yellow in products to

supervise sunset yellow in food production and processing.

At present, high performance liquid chromatography (HPLC)6,7, thin layer

chromatography8, capillary zone electrophoresis9,10, enzyme linked immunosorbent

assay11, spectrophotometry12, electrochemical method13 and fluorescence sensing

analysis method14 are often used to detect the content of sunset yellow in food. However,

most of them have low sensitivity, are time consuming, require expensive equipments

and have low detection limit. In modern research, the fluorescence sensing analysis

method based on nanoparticles has attracted wide attention because of its high

sensitivity, good selectivity, short response time, simple operation, portable monitoring,

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and relatively low cost15,16.

In recent years, semiconductor nanoparticles have attracted more and more attention

in the fields of biomedicine and chemical analysis. However, most of them are toxic,

which hinders the further development of nanoparticles in the field of biology and

chemical analysis. Recent studies17,18 have shown that silicon nanoparticles (SiNPs) has

low toxicity, and has excellent properties such as abundant silicon reserves, good water

solubility, strong photostability, low toxicity, good biocompatibility, adjustable

fluorescent emission, high fluorescence quantum yield and so on. At the same time, as a

new type of fluorescence probe, SiNPs have been widely used in chemical analysis19,20,

biomedicine21,22 and other research fields23. However, compared with traditional

semiconductor quantum dots, metal nanoclusters and carbon quantum dots, the research

and application of SiNPs in the field of chemical sensing is still limited24. Up to now,

researchers have established many methods for the synthesis of fluorescent SiNPs, the

most widely used methods are microwave-assisted methods25,26, hydrothermal

methods27,28, electrochemical etching method29 and ultraviolet radiation method30, but

most of them require stringent reaction conditions (such as high temperature, high

pressure, complex instruments and equipment, etc). Therefore, it is of great significance

to study the simple method of preparing SiNPs at room temperature or mild conditions.

At present, the research on SiNPs as a fluorescent probe is mainly used in biological

and chemical applications, but there are no reports about sunset yellow in foods or

beverages. In view of this, we invented a simple one-step method to prepare fluorescent

SiNPs probe at room temperature for rapid, sensitive and highly selective determination

of sunset yellow in beverages.

6

Experimental

Reagents and chemicals

Gatorade beverage was bought from the local supermarket.

N-(2-aminoethyl)-3-aminopropyltriethoxysilane (N-APTES) was obtained from

Shanghai Aladdin Biochemical Technology Co., Ltd; L-sodium ascorbate and sodium

chloride were received from Tianjin Damao Chemical Reagent Factory; glucose,

sucrose, maltose and sodium benzoate were received from Tianjin Guangfu Science and

Technology Development Co., Ltd; potassium sorbate, sodium citrate, citric acid and

L-phenylalanine were obtained from Shanghai Zhongqin Chemical Reagent Co., Ltd;

sodium pyrosulfite, vitamin C, lemon yellow and carmine were obtained from Tianjin

Yilenda Chemical Co., Ltd, the above reagents are all of analytical reagent grade.

Sunset yellow is chromatographically pure, purchased from Shanghai Yuanye

Biotechnology Co., Ltd.

Apparatus

FTIR-650 spectrometer was used to record Fourier transform infrared spectroscopy

(FT-IR) which was received from Tianjin Gangdong Science and Technology Co., Ltd;

TU-1810 UV-Vis spectrometer was obtained Beijing General Instruments Co., Ltd to

record absorption spectra. By setting the emission and excitation slits at 10 nm, the

fluorescence analysis was conducted by F-4700 spectrofluorophotometer which was

obtained Foundachi Hi-Tech Co., Ltd.

Synthesis of SiNPs

The probe of SiNPs was synthesized based on a previously reported method which is

a low temperature procedure31. with slight modification: 1.0 mL N-APTES was added to

5.0 mL deionized water and stirred at room temperature for 5 min. Then 3.0 mL 0.05 M

7

sodium L-ascorbate was added and stirred for 40 min, to form SiNPs. The prepared

SiNPs were dialyzed by dialysis membrane (molecular weight interception: 1000 Da)

for 12 hours, and then stored at 4℃ for further use.

Fluorescence measurements

The SiNPs solution (1.0 mL) was added to 2.0 mL Phosphate Buffer Saline (PBS),

with pH = 4.0. Then different concentrations of SY solution (1.0 mL) were mixed

thoroughly, and left for 1 min. The fluorescence spectra were measured at excitation

wavelength of 360 nm (the width of the excitation and emission slits were both 10 nm).

The concentration of SY was calculated by working curve. The selectivity of the SiNPs

probe towards SY was conducted after addition of interfering substances in place of SY

in the same way. All experimental procedure was conducted at room temperature.

Analysis of real samples

The soft drinks were purchased from the local supermarket. About 1.0 mL of silicon

nanoparticles solution, 2.0 mL of PBS (pH = 4.0), and different concentrations of sunset

yellow standard (1.0 mL) solution were added to a series of 10 mL colorimetric tubes,

the fluorescence intensity of mixing solution was then measured by F-4700 fluorescence

spectrophotometer, at 360 nm excitation wavelength, with both excitation and emission

slits set to 10 nm.

Results and Discussion

Optimization of reaction parameters of SiNPs

Using one-step method, SiNPs were obtained by mixing N-APTES and sodium

L-ascorbate, with continuous stirring at room temperature. The synthesized SiNPs

revealed the best fluorescence properties after optimizing the reaction parameters which

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included the concentration of sodium L-ascorbate and the reaction time. Fig. 1A shows

that the fluorescence intensity of SiNPs varies with the concentration of sodium

L-ascorbate solution. The results revealed that at 0.05 M concentration of sodium

L-ascorbate, the fluorescence intensity of SiNPs solution was the highest, however,

further increase of the concentration of sodium L-ascorbate solution led to a gradual

decrease of the fluorescence intensity of SiNPs. Fig. 1B depicts the change of

fluorescence intensity of SiNPs solution with reaction time. The results showed that the

fluorescence intensity of SiNPs solution increased gradually with the increase of

reaction time in the range of 10 min ~ 40 min. When the reaction time was higher than

40 min, the fluorescence intensity of SiNPs solution decreased at first, and then

increased again. In further experiments, 40 min and 0.05 M were selected as the

reaction time and concentration of the reducing agent, respectively, for the synthesis of

SiNPs.

Characterization of SiNPs

In this experiment, a Transmission Electron Microscope (TEM) was used to

characterize the morphology of the SiNPs solution. As shown in Fig 2A, the SiNPs

prepared in this experiment was spherical, with good dispersion, and uniform particles

diameter. The size of SiNPs was about 2.0 ~ 2.6 nm and the average diameter was 2.3

nm (Fig. 2B). Fig 2C shows the Fourier transform infrared spectrograph (FT-IR) of the

SiNPs, with the broad absorbance peaks at 3270 cm-1 and 1570 cm-1 depicting the

stretching vibration and bending vibration of the N-H. The absorbance in the range of

2932 cm-1 and 1468 cm-1 showed the stretching vibration and bending vibration of C-H,

and the strong absorbance at 1020 cm-1 related to the stretching vibration of Si-O-Si

bonding. In addition, the optical properties of the obtained SiNPs were confirmed by

UV-vis absorption and fluorescence spectra as shown in Fig. 2D. It could be seen from

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the UV absorption spectrum that SiNPs had absorption at the wavelengths of 329 nm.

From the fluorescence spectrum, the excitation wavelength of SiNPs was 370 nm, and

the maximum emission wavelength was 465 nm. The fluorescence emission spectra of

SiNPs at different excitation wavelengths are also depicted in Fig. 2E. It could be seen

from the figure that the position of fluorescence emission peak of SiNPs did not change

with the varying excitation wavelength which indicated that the fluorescence emission

peak of SiNPs did not have excitation wavelength dependence, it might be closely

related to the uniform surface state of SiNPs32. the SiNPs solution was analyzed with

EDS pattern, as shown in the Fig. 2F. From the figure, the analysis clearly showed the

presence of silicon, carbon, oxygen, and nitrogen in SiNPs.

Furthermore, the surface composition and elemental analysis of the obtained SiNPs

were further measured via X-ray photoelectron spectroscopy (XPS). Fig. 3A exhibit five

major peaks at 531.4 eV, 400.6 eV, 284.3 eV, 154.7 eV and 105.4 eV, which were

assigned to O 1s, N 1s, C 1s, Si 2s, and Si 2p, respectively. The XPS spectrum of C 1s

(Fig. 3B) exhibited five fitted peaks which were associated with C=O (288.1eV),

C-OH/C-O-C (286.3 eV), C-N (285.7 eV), C-C/C=C (284.7 eV), and C-Si (284.0 eV)

groups. The three fitted peaks at 400.8 eV, 399.7 eV and 398.8 eV in the N 1s spectrum

(Fig. 3C) were ascribed to N-(C)3, C-N-C and N-Si groups. The three fitted peaks at

532.8 eV, 532.1 eV and 531.3 eV in the O 1s spectrum (Fig. 3D) were associated with

Si-O, C-OH/C-O-C and C=O groups. The three fitted peaks at 102.8 eV, 102.2 eV and

101.6 eV in the Si 2p spectrum (Fig. 3E) were ascribed to Si-O, Si-N, and Si-C groups.

The surface constitution of the SiNPs determined by XPS was consistent with the FT-IR

results. The XRD patterns of the SiNPs exhibited one broad peak at 2θ ≈ 21◦;

furthermore, no diffraction peaks were detected for crystalline silicon or crystalline

silica(Fig. 3F). The absolute photoluminescence quantum yield of the synthesized Si

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QDs was ~3.0%.

Stability of the SiNPs

The influence of SiNPs in different concentrations of NaCl solution, different

temperatures and pH on its fluorescence intensity was also studied. Firstly, the

fluorescence intensity of SiNPs solution under different concentrations of NaCl solution

was investigated, and the results were displayed in Fig. 4A. When the NaCl

concentration changed from 0 mM to 1000 mM, the fluorescence intensity of the SiNPs

solution remained relatively stable, indicating that the SiNPs solution had a relatively

excellent salt resistance. As shown in Fig. 4B, when the temperature was increased from

20℃ to 90℃, the fluorescence intensity of SiNPs hardly changed, which indicated that

SiNPs exhibited good thermal stability. Furthermore, in Fig. 4C, as the pH increased

from 2.0 to 4.0, the fluorescence intensity of SiNPs increased gradually. However, when

the pH increased from 4.0 to 9.0, the fluorescence intensity of SiNPs remained

unchanged. As the pH further increased from 9.0 to 12.0, the fluorescence intensity

gradually decreased. This phenomenon is probably ascribed to the different protonation

ratio of amine group at various pH, the protonation ratio of surface amine group

decreases gradually with further increase of solution pH33.

Detection of sunset yellow by SiNPs

Considering that the safety detection of SY may need to be carried out on site，the

detection time matters. The response time of the SiNPs solution to the sunset yellow

was investigated. As depicted in Fig. 5A, the fluorescence intensity of SiNPs was stable

when pH was between 4.0 and 9.0. Therefore, in this experiment, sunset yellow was

detected in PBS buffer solution (pH = 4.0). As seen in Fig. 4A, the response time of

SiNPs to SY was very short, the equilibrium time was reached within 1 min. Also, when

different concentrations of sunset yellow solution were added to SiNPs, the fluorescence

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intensity of SiNPs decreased gradually with the increase of SY’s concentration (Fig.5B).

From Fig. 5C, there was a good linear relationship between the fluorescence quenching

efficiency F0/F and the SY solution in the range of 0.050 μg mL-1 ~ 14.0 μg mL-1, with a

detection limit (3σ/k) of 0.023 μg mL-1.

Selectivity of SiNPs for SY

In order to ascertain whether the SiNPs was selective for detecting SY, the

interference of coexisting substances in soft drinks were investigated in this experiment.

10.0 μmol/L of lemon yellow (LY) carmine (Car), 1mmol/L of sodium benzoate (SB),

trisodium citrate dihydrate (TCD), potassium sorbate (PB), sodium pyrosulfite (SP),

sucrose (Suc), glucose (Glu), maltose (Mal), Ca2+, Na+, Zn2+, or Mg2+was added to the

system as interfering substance. Only the addition of SY had a significant effect on the

fluorescence intensity of SiNPs (Fig. 6A). At the same time, in the experiment, the

anti-interference ability of SiNPs were determined by mixing interference substances

and SY solution. As shown in Fig. 6B, the fluorescence intensity of the SiNPs solution

was basically the same as when only SY was added. These results showed that SiNPs

had a good selectivity and anti-interference ability for the detection of SY.

Quenching mechanism

To investigate the quenching mechanism between SY and SiNPs, a corresponding

experiment was conducted. It is considered an inner filter effect (IFE) quenching

mechanism when a spectral overlap occurs between the UV-vis absorption spectrum of

the quencher and the excitation spectrum of the fluorescent agent. As demonstrated in

Fig. 7A, the excitation spectrum of SiNPs barely overlapped with the absorption

spectrum of SY, indicating that IFE may not be the fluorescence quenching mechanism.

Subsequently, the role of fluorescence resonance energy transfer (FRET) in this system

was also studied. As displayed in Fig. 7A, there was a large spectral overlap between the

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absorption spectrum of SY and the emission spectra of SiNPs, and After sunset yellow

was added into Si NPs solution, the fluorescence lifetime of the material changed

(Fig.7B), indicating that FRET may be the main possible mechanism for fluorescence

quenching of SiNPs by SY.

Analysis of sunset yellow in real samples

In order to evaluate the feasibility of the mentioned method for detection of SY in

actual samples, the fluorescent probe was applied to determinate SY in soft drinks. The

soft drinks were used directly without any treatment, and the results are presented in

Table 1. The recovery rate of SY by the standard addition method in samples ranged

from 93.8% ~ 102.4% with a relative standard deviation of less than 2.6% (n=3). The

national standard in China "Hygienic standard for the use of food additives"

(GB2760-2011) stipulates that the maximum amount of SY used in carbonated drinks is

0.10 g kg-1. According to the experiment, the SY content of the soft drinks met the

health standard. The results showed that this new method is accurate and reliable, and

can be used to determine the content of SY in real samples.

Comparison with other studies

Up to now, methods based on HPLC6, thin layer chromatography8, capillary zone

electrophoresis10, enzyme linked immunosorbent assay11, spectrophotometry12,

electrochemistry13 and fluorescent sensing14 have been used for determination of SY.

Among these methods, fluorescent sensing has lower detection limit and costs shorter

time than the chromatography methods, has better reproducibility and needs less time

than the capillary zone electrophoresis methods, costs less than the spectrophotometry

and enzyme linked immunosorbent assay methods. And in the reported fluorescent

sensing methods, the SiNPs used in this work are easier to prepare and prepared under

milder conditions. Some methods for sunset yellow detection are listed in Table 2.

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Conclusions

In this study, a simple one-step method was used to synthesize water-soluble silicon

nanoparticles. This method did not involve multi-steps synthesis and time-consuming

modification process. The fluorescent SiNPs had good thermal stability, excellent salt

tolerance, and good pH stability. Based on the excellent properties of SiNPs and the

effective quenching of silicon nanoparticle fluorescence by sunset yellow, a new probe

for the determination of sunset yellow in beverages was established. With its excellent

selectivity and sensitivity, this method provides a convenient method for the detection

of pigment additives in food.

Acknowledgements

This work was supported by the Scientific Research Start-up Funds of Gansu

Agricultural University (No. GAU-KYQD-2018-10) and Whole chain regional

comprehensive demonstration of food safety monitoring and control technology

(2019YFC1606500).

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References

1. A. Basu, and G. S. Kumar. Food Chem., 2010, 29, 107.

2. A. H. Aktaş, and G. P. Ertokuş. Rev. Anal. Chem., 2010, 29, 107.

3. P. Mpountoukas, A. Pantazaki, and E. Kostareli, Food Chem. Toxicol., 2010, 48,

2934.

4. K. Rovina, L. A. Acung, S. Siddiquee, J. H. Akanda, and S. M. Food Anal.

Methods, 2017, 10, 773.

5. S. Opinion. EFSA. J., 2014, 12, 1.

6. A. Islam, M. Sarker, S. H. Khan, I. Hossain, Z. Abedin, and A. Zubair, J. Food Sci.,

2019, 31, 184.

7. C Tatebe, T Ohtsuki, N Otsuki. Am. J. of Anal. Chem., 2012, 3, 570.

8. T. X. Tang, X. J. Xu, D. M. Wang, Z. M. Zhao, L. P. Zhu, and D. P. Yang. Food

Anal. Methods, 2015, 8, 459.

9. J. Feng, J. Li, W. Huang, H. Cheng, Z. Zhang, and L. Li. Food Anal. Methods,

2020, 1.

10. L. D. Giovine, and A. P. Bocca. J. Food, Hyg. Soc. Japan, 2003;45, 150.

11. Y. Xing, M. Meng, H. Xue, T. Zhang, Y. Yin, and R. Xi. Talanta, 2012, 99, 125.

12. B. Soleymani, B. Zargar, and S. Rastegarzadeh. Food Addit & Contam: Part A.,

2019, 36, 1605.

13. J. Wang, B. Yang, H. Wang, P. Yang, and Y. Du. Anal. Chim. Acta., 2015, 893,

41.

14. Q. T. Tran, T. T. Phung, Q. T. Nguyen, T. G. Le, and C. Anal. Bioanal. Chem.,

2019, 411, 7539.

15

15. Y. Zhong, F. Peng, F. Bao, S. Wang, X. Ji, and L. Yang. J. Am. Chem. Soc., 2013,

135, 22, 8350.

16. X. Sun, and Y. Lei. TrAC Trends Anal. Chem., 2017, 89, 163.

17. X. Zhang, X. Chen, J. Yang, H. R. Jia, Y. H. Li, and Z. Chen. Adv. Funct. Mater.,

2016, 26, 5958.

18. Z. Ding, B. M. Quinn, S. K. Haram, L. E. Pell, B. A. Korgel, and A. J. Bard.

Science, 2002, 296, 1293.

19. J. Zhang, and S. H. Yu. Nanoscale, 2014, 6, 4096.

20. J. Zhao, J. Deng, Y. Yi, H. Li, Y. Zhang, and S. Yao. Talanta, 2014, 125, 372.

21. S. D. Ma, Y. L. Chen, J. Feng, J. J. Liu, X. W. Zuo, and X. G. Chen. Anal. Chem.,

2016, 88, 10474.

22. S. Sinha, W. Y. Tong, N. H. Williamson, S. J. P. McInnes, S. Puttick, and A.

Cifuentes-Rius. ACS. Appl. Mater. Inter., 2017, 9, 42601.

23. F. B. Juangsa, M. Ryu, J. Morikawa, and T. Nozaki. J. Phys. D: Appl. Phys., 2018,

51, 505301.

24. H. L. Ye, S. J. Cai, S. Li, X. W. He, W. Y. Li, and Y. H. Li. Anal. Chem., 2016, 88,

11631.

25. X. Ji, C. Wang, M. Tang, D. Guo, F. Peng, and Y. Zhong. Nanoscale, 2018, 10,

14455.

26. S. Wu, Y. Zhong, Y. Zhou, B. Song, B. Chu, and X. Ji. J. Am. Chem. Soc., 2015,

137, 14726.

27. J. Wang, R. Li, X. Long, and Z. Li. Sens. Actuators B Chem. 2016, 237, 740.

28. N. Dhenadhayalan, H. L. Lee, K. Yadav, K. C. Lin, Y. T. Lin, and A. H. H. Chang.

ACS Appl. Mater. Inter., 2016, 8, 23953.

29. Y. Yi, G. Zhu, C, Liu, Y. Huang, Y. Zhang, H. Li. Anal. Chem., 2013, 85, 11464.

16

30. Y. Zhong, X. Sun, S. Wang, F. Peng, F. Bao, and Y. Su. ACS Nano., 2015, 9,

5958.

31. Y. K. Dou, Y. Chen, X. W. He, W. Y. Li, Y. H. Li, and Y. K. Zhang. Anal. Chem.,

2017, 89, 11286.

32. Y. Han, Y. Chen, J. Feng, J. Liu, S. Ma, and X. Chen. Anal. Chem., 2017, 89,

3001.

33. Y. Q. Dong, H. C. Pang, H. B. Yang, C. X. Guo, J. W. Shao, Y. W. Chi, and C. M.

Li. Angew. Chem. Int. Ed. Engl., 2013, 52, 30.

34. H. Yang, Y. Long, H. Li, S. Pan, H. Liu, and J. Yang. J. Colloid. Inter. Sci., 2018,

516, 192.

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Fig. Captions:

Scheme 1 Schematic illustration of synthesis process of SiNPs and detection

principle for SY.

Scheme 2 The chemical structures of sunset yellow.

Fig. 1 (A) Effect of amount of sodium ascorbate. (B) Reaction temperature on FL

intensity of the SiNPs.

Fig. 2 (A) TEM pattern. (B) Diameter distribution of the SiNPs. (C) FT-IR image

of SiNPs. (D) excitation spectrum, emission spectrum and ultraviolet absorption

spectrum. (E) fluorescence emission spectrum of the SiNPs at various excitation

wavelengths. (F)EDS pattern.

Fig. 3 High resolution XPS spectra of the SiNPs: (A) full range, (B) C 1s, (C) N

1s, (D) O 1s, (E) Si 2p, (E) XRD spectrum of SiNPs.

Fig. 4 (A) Fluorescence intensity of SiNPs in different concentrations of NaCl

solution. (B) Fluorescence intensity of SiNPs in different temperature. (C)

Fluorescence intensity of SiNPs in different pH (where F0/F and F represented the

fluorescence intensity without and with experimental treatment, respectively).

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Fig. 5 (A) Response time between SiNPs and SY, (B) effect of different SY

concentration (from top to bottom, 0.05, 0.15, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9,10,11,

12, 13 and 14 μg mL-1) on SiNPs fluorescence. (C) linear relationship between

F0/F and SY concentration (where F0 and F represent the fluorescence intensity

without and with SY, C represent the concentration of SY, respectively).

Fig. 6 (A) The fluorescence quenching efficiency F0/F of SiNPs towards SY and

other interferers. (B) the fluorescence quenching efficiency F0/F of SiNPs

towards SY and other interferers in the presence of SY (where F0 and F

represented the fluorescence intensity without and with SY or other interferers).

Fig. 7 (A) UV-vis absorption spectra of SY and emission and excitation spectra

of SiNPs, (B) Lifetimes of steady-state fluorescence of SiNPs and SiNPs + SY.

19

20

A

F

21

22

23

24

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Table 1 Real sample analysis

Samples Added

(μg mL-1)

Determined

(μg mL-1) Recovery, % RSD, %

0 0 0.21 — —

1 12.0 12.5 102.4 1.4

2 13.0 12.4 93.8 2.6

3 15.0 15.5 101.9 2.4

Table 2 Comparison with other determination methods of SY

Method Linear range

(μg mL-1)

Detection limit

(μg mL-1) Remarks

HPLC6 NG 11.400

High detection limit, time

consuming and expensive

equipment

Electrochemical13 0.009-49.372 0.009 complex equipment and time

consuming

Capillary zone

electrophoresis10 0.005-0.100 0.005

complex preparation process

and poor reproducibility

Carbon dots34 0.080-32.000 0.024 high temperature preparation

This work 0.050-14.000 0.023 Sensitive, fast, simple and

efficient

NG: not given.