A new and highly selective turn-on fluorescent sensor with fast response time for the monitoring of cadmium ions in cosmetic, and health product samples

Article abstract of DOI:10.1016/j.saa.2016.03.011

Cadmium (Cd) which is an extremely toxic could be found in many products like plastics, fossil fuel combustion, cosmetics, water resources, and wastewaters. It is capable of causing serious environmental and health problems such as lung, prostate, renal c

Full text of DOI:10.1016/j.saa.2016.03.011

A new and highly selective turn-on fluorescent sensor with fast response time
for the monitoring of cadmium ions in cosmetic, and health product samples
Rouhollah Khani, Ebrahim Ghiamati, Ramin Boroujerdi, Abdolreza
Rezaeifard, Mohadeseh Hosseinpour Zaryabi
PII:
DOI:
Reference:
S1386-1425(16)30113-5
doi: 10.1016/j.saa.2016.03.011
SAA 14324
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Accepted date:
23 November 2015
9 March 2016
11 March 2016
Please cite this article as: Rouhollah Khani, Ebrahim Ghiamati, Ramin Boroujerdi,
Abdolreza Rezaeifard, Mohadeseh Hosseinpour Zaryabi, A new and highly selective turn-
on fluorescent sensor with fast response time for the monitoring of cadmium ions in
cosmetic, and health product samples, (2016), doi: 10.1016/j.saa.2016.03.011
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A new and highly selective turn-on fluorescent sensor with fast response time for the
monitoring of cadmium ions in cosmetic, and health product samples
Rouhollah Khani, Ebrahim Ghiamati*, Ramin Boroujerdi, Abdolreza Rezaeifard,
Mohadeseh Hosseinpour Zaryabi
Department of Chemistry, Faculty of Science, University of Birjand, P.O. Box 414, Birjand, Iran
Abstract
Cadmium (Cd) which is an extremely toxic could be found in many products like plastics,
fossil fuel combustion, cosmetics, water resources, and wastewaters. It is capable of causing
serious environmental and health problems such as lung, prostate, renal cancers and the other
disorders. So, the development of a sensor to continually monitor cadmium is considerably
demanding. Tetrakis(4-nitrophenyl) porphyrin, T(4-NO2-P)P, was synthesized and used as new
and highly selective fluorescent probe for monitoring cadmium ions in the “turn-on” mode.
There was a linear relationship between fluorescence intensity and the concentration of Cd(II) in
the range of 1.0 × 10-6 to 1.0 × 10-5 mol L-1 with a detection limit of 0.276 μM. To examine the
most important parameters involved and their interactionsin the sensor optimization procedure, a
four-factor central composite design (CCD) combined with response surface modeling (RSM)
was implemented. The practical applicability of the developed sensor was investigated using real
cosmetic, and personal care samples.
Keywords: Turn-on sensor; Fluorescent probe; Porphyrin; Multivariate optimization; Cadmium;
Cosmetic samples.
*Corresponding author. Tel: +985632202065, ext. 336
E-mail address: eghiamati@birjand.ac.ir
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1. Introduction
Heavy metals, are one of the main sources of pollution in environment, especially because
of their significant effects on biological systems. The importance of heavy metals determination
at trace levels is due to their rapid diffusion as environmental contaminants [1,2], to the
surroundings. Cadmium is toxic even at low levels and has influence on various biological
processes [3-7]. Cadmium is a naturally occurring non-essential trace element and has a tendency
to bioaccumulates in living organisms, raising environmental concerns [8,9]. Cadmium is ranked
seventh in priority list of top 275 hazardous material on Comprehensive Environmental
Response, Compensation, and Liability Act in USA [10,11]. Furthermore, the accumulation of
cadmium in the human body can damage important internal organs like liver, lung, kidneys,
central nervous system and bones [12,13]. Epidemiological studies conducted in general human
populations have shown that Cd increases the risk of developing breast, prostate, and
endometrial cancers [14-17].
Many attempts have been made during the last two decades to develop different methods
for detecting cadmium, including electrochemical methods such as differential pulse anodic
stripping voltammetry [18,19], optical spectroscopic methods like flame atomic absorption
spectrometry [7,20], and inductively coupled plasma mass spectrometry [21]. The problems with
these techniques are the requirements for expensive instrumentation, specialized operator, and
long analysis time. Spectrofluorometric and spectrophotometric methods, like Dual-Signaling
Fluorescent (DSF) [22] were used to detect trace amount of metal ions, too. Fluorescent and
colorimetric-based chemosensors are widely utilized for measuring the amount of cadmium ions
in solutions [23-36].
Due to unique properties of fluorescence techniques, many detection methods have been
emerged for speciation of analytes, such as heavy metal ions, mostly by studying the emission
spectra like peak shifting [37], quenching [38,39], or enhancement [40-42]. The development of
optical sensing approaches in designing sensors and biosensors for the detection of
environmentally and biologically important species, such as toxic heavy metal ions, has been an
inevitable task. A fluorescence-based optical sensor is one of the most practical application of
these endeavors, because of its intrinsic sensitivity, high selectivity, specificity, real-time
monitoring with fast response time and undamaging effects on the analytes [43-45].
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On the other hand, the porphyrins are macrocyclic compounds constituting 1:1 complexes
almost with all the metal ions. Mg(II), Cd(II) and Zn(II) in their porphyrin complexes, readily
combine with one more ligand to form pentacoordinated complexes with square-pyramidal
structure [46]. Porphyrins reactions with large metal ions like Cd(II), are relatively fast, because
they cannot fit into the porphyrin nucleus and just sit on top of the molecule [47]. Porphyrin
based sensory methods were widely used during the past decade because of their ability to
interact with metal ions. Many of the newly developed Cd turn-on sensors capable of detecting
Cd and Zn are unable to function selectively only for cadmium [48-52]. In this work T(4-NO2-
P)P was employed as a specific turn-on fluorescent probe to quantify cadmium ions in real
samples. The influence of important variables such as temperature, time of response, the amount
of the reagent and the concentration of zinc on function of the sensor were investigated. The
optimization was carried out via a 24 full factorial central composite design (CCD) combined
with response surface methodology (RSM) to maximize sensor efficiency of the target analyte.
In this methodology, the interactions of two or more variables could be studied simultaneously,
resulting in higher percentage yields, reduced process variability, closer confirmation of the
output response to nominal and target achievement, and less treatment time with minimum costs
[53].
2. Experimental
2.1 Reagents
2.1.1. Chemicals
All chemicals were purchased from Merck (Darmstadt, Germany) and were of analytical
reagent grade. Absolute ethanol (Merck) was used for preparing the respective solutions. The
metal ions stock solutions were made up of their nitrate and chloride salts. The Hg (II) ions were
of its acetate salt. Double distilled deionized water was used for solutions dilution.
2.1.2. Real Samples
Three real samples were chosen, i) A Kiss Beauty pink-purple lipstick; ii) An Atusa brown hair
color from Sabzgolsar Co. under the supervision of Jos. H. Lowenstein, USA; and iii) My Lang
Anhaltendes liquid foundation make up cream manufactured by ACT Cosmetics Co. (under the
license of Kahl & Co, Germany).
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2.2. Instrumentation and software
Photoluminescence (PL) spectra were obtained using a Shimadzu RF-5301PC
spectrofluorometer (Japan) at room temperature (298 ± 2 K). UV-Visible spectra were acquired
by A-160 Shimadzu UV-Vis equipped with a photomultiplier tube (PMT) detector. AA-6300
Shimadzu (Japan) atomic absorption spectrometer (AAS) equipped with a deuterium lamp
background correction and cadmium hollow cathode lamp was used as a source for
determination of cadmium. The lamp was operated at optimum condition expressed by the
manufacture. For centrifugation, Hettich Zentrifugen Model EBA 200 was used. Wisettir model
MSH-20D was utilized for magnetic stirring of the solutions.
2.3. Software
The Design-Expert, a statistical package software version 9.0 (Stat-Ease Inc.,
Minneapolis, MN, USA) was used for experimental design analysis and subsequent regression
analysis of the experimental data. The proposed three dimensional molecular structure was
drawn using Chem & BioDraw Ultra version 11.0 of Cambridge Soft products.
2.4. Central composite design
The central composite design (CCD) was used to signify the effects of involved parameters
including temperature, time of response, amount of the T (4-NO2-P)P and the concentration of
zinc. Due to the similarity between the structure of Zn2+ and Cd2+ metal ions and the low
fluorescence response of the proposed sensor to the zinc ions, the concentration of zinc plus
three of above mentioned factors was examined using Design-Expert 9.0. A five-level CCD was
implemented to evaluate the influence of the quantities on fluorescence intensity (Table 1)
leading to 30 runs for the optimization process. Table 2 shows the experimental design points
consist of 2n factorial points with 2n axial points along Nc central points and the test results for
the response variables. The center points are used to estimate the experimental errors and the
reproducibility of the data.
Fulfilling the response surface methodology (RSM) role, followed by the implementation of
optimization and performing distinct experiments allow us to determine the relative significance
of parameters on the process even in systems with complex interactions. The modeling was
conducted to derive the first or second-order polynomial equations. Then the analysis of
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variances (ANOVA) were plotted in a three dimensional graphs. The outcome leads to a surface
response, corresponding to a response function which is always used for the prediction of real
optimum points.
2.5. Preparation of real samples
To validate the proposed method, it was applied to determination of cadmium in three real
samples, one a lipstick; the other, a brown hair coloring, and the last, the liquid foundation
makeup cream. One g of a real sample was taken (lipsticks were sliced to tiny pieces) and was
placed in a beaker. Then 8.0 mL of HNO3 (65%) and 2.0 mL of acetone were added to it. The
solution left intact for 24 h. After that, it was filtered. The filtrate was centrifuged in speed of
4000 rounds per minute (rpm) for 30 minutes to remove the colloidal fine particles. The upper
solution was separated from the solid and dried. The dried material was added to a beaker
containing absolute ethanol, stirred with stirring rod at 1500 rmp for 2 h till Cd (II) was
dissolved. The solid material was removed by centrifugation, and the solution was assayed for
Cd(II) by the developed fluorescence sensor and AAS. The same procedure was repeated for the
other two samples.
3. Results and discussion
3.1. Synthesis of T(4-NO2-P)P
Tetrakis(4-nitrophenyl)porphyrin was synthesized by using A. Bettelheim et al. method[54],
with some changes for increasing the yield of the reaction, which briefly explained here. An
11.03 g (73 mmol) 4-nitrobenzaldehyde and 127 mmol of acetic anhydride were added to 300
mL of stirring propionic acid. After the solution was brought to reflux, 5.06 mL (73 mmol) of
freshly distilled pyrrole in 10 mL of propionic acid was added. The dark solid was collected by
filtration, washed three times with water, and finally dried. The extracted solid material was
dissolved into 80 mL of pyridine, and refluxed for an hour. After cooling, the final product was
washed with acetone. Fig. 1 shows the UV-Vis spectrum of the synthesized T(4-NO2-P)P. Our
method produced 19-22% yield which was five times improvement in comparing to ref. 54
method. The molecular structure of the synthesized porphyrin ring has been shown in Fig. 2.
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3.2. Fluorescence measurements
A solution with concentration of 1.0 × 10-4 mol L-1 of the T(4-NO2-P)P was prepared in
chloroform. Scanning the spectrum in UV-Visible region showed a sharp peak at 420 nm.
Therefore, 420 nm was selected for further studies.
Eighteen stock solutions of 1.0 × 10-3 mol L-1 from different metal ions (Mg2+, Na+, Zn2+,
Al3+, Mn2+, K+, Cd2+, Hg2+, Ag+, Co2+, Ni2+, Ca2+, Pb2+, Cu2+, Cr2+, Ce3+, Fe2+, Fe3+) were made
in ethanol. Another stock solution of 1.0 × 10-4 mol L-1 T(4-NO2-P)P in chloroform was also
prepared. From first series of the stock solutions, a solution of 8.0 × 10-5 mol L-1 of each metal
ions of was mixed with 1.0 × 10-5 mol L-1 of the T(4-NO2-P)P and diluted to the mark with
ethanol. Fluorescence spectra for these were recorded at 608 nm (λexc: 420 nm).
As can be seen in Fig. 3, no obvious changes in emission spectra were observed upon the
addition of different metal ions except for Zn2+ and Cd2+ solutions, which leads to appearance of
a peak at 608 nm (λexc: 420 nm). The intensity of this peak in the presence of Cd ions was
dramatically greater with respect to Zn2+ ions. The highly selective response of the T(4-NO2-P)P
to Cd2+ ions make it suitable for sensory usage (Fig. 4).
3.3. Mechanism of fluorescence
The change in the fluorescence spectrum of T(4-NO2-P)P in the presence of different
cations is due to the interactions of the four non-core nitro groups of the porphyrin with the
cation (Fig. 5). According to literatures, the porphyrin core of meso-tetra(aryl)porphyrins with no
steric hindrance at the meso positions is planar or nearly planar[55], and therefore the non-
bonding electrons of the central nitrogen atoms cannot coordinate to the metal ion. On the other
hand, these interactions cause deviation from planar configuration, leading to color change. No
color change was observed confirming our proposed mechanism, i.e., interaction of NO2 with Cd
(II) which causes fluorescence turn-on is correct. Substituents attached to the meso aryl groups
such as terpyridine [56], or functional groups such as carboxylate [56-58], may form
coordinative bonds with metal cations such as Cd(II). The formation of such complexes were
reported for Cd(II) in reaction with the functional groups of different aromatic ligands and nitrate
anion [59].
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3.4. Optimization of sensor efficiency using response surface methodology (RSM) approach
3.4.1. Interpretation of the regression analysis
Analysis of variance (ANOVA) using Design-Expert 9.0 (Table 3) produces useful
information about the significance and magnitude of the effect on the main variables and their
interactions. A p-value of less than 0.05 indicates the statistical significance of an effect at 95%
confidence level. The “Lack of Fit” (LOF) p-value is 0.0645 which simultaneously confirms the
suitability of the model for well-fitting of the experimental data, and demonstrates the
insignificance LOF meaning that the other interactions are not significant with respect to the pure
error. F-test was used to estimate the statistical significance of all terms in the polynomial
equation within 95% confidence interval. Based on the data analysis the expression for
evaluation of fluorescence intensity was obtained as follows:
Flu. Intensity = +207.49 -125.34*A -7.37*B -0.43*C -18.79*D -20.74*AB+1.60*AC +14.43
*AD +0.92*BC +19.05*BD +3.77*CD +33.04*A2 +20.33*B2 +2.17*C2 -2.03*D2
(1)
ANOVA results imparting this quadratic model could be utilized to navigate through the
design space. As can be seen in Table 3 the P-value for fluorescence intensity of Cd (II) (p-value
<0.0001) is lower than 0.05 conveying that quadratic model is significant. High value of R2
(94.0%) and R2 (adjusted) (90.0%) signifies a high dependency and correlation between the
observed and the predicted values of response.
3.4.2. Interpretation of residual graphs and 3D plots
The normal probability plot (NPP) is a graphical technique for assessing whether or not a
data set is approximately normally distributed [60]. The residual is the difference between the
observed and the predicted value (or the fitted value) from the regression. If the points on the
plot fall fairly close to the straight line then the data are normally distributed. Fig. 6 illustrates
NPP of residual values. It could be seen that the experimental points were reasonably aligned
suggesting normal distribution was happened.
RSM application following CCD assists researchers to optimize the critical factors and to
provide useful information about response nature. Fig. 7 represents the relevant fitted response
surfaces for the design and depicts the response surface plots of fluorescence intensity versus
respective variables, while their curvatures illustrate the presence of interactions among
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variables. The response surface plots (Fig. 7 a–c) indicate the dependency of fluorescence
intensity on variables such as temperature, time of reaction and concentration of the T(4-NO2-
P)P. In addition to, Fig. 7a confirms that maximum Cd(II) fluorescence intensity could occur at a
temperature 298 K or at room temperature. According to Fig. 7b, it was found that Cd(II) has
maximum fluorescence intensity in the first 25 min of reaction time. Fig. 7c illustrate that the
temperature and time of reaction have negative correlation with the Cd(II) fluorescence intensity.
It is noteworthy to mention that there is no significant interaction between these factors.
3.4.3. Optimization of CCD by desirability function (DF) for Cd(II) sensor performance
The profile for predicted values and desirability option in the Design-Expert, Stat-Ease Inc.
9.0 software was used for the optimization process. This procedure involves specifying the DF
for the dependent variable (fluorescence intensity) by assigning predicted values. The scale in the
range of 0.0 (undesirable) to 1.0 (very desirable) was used to obtain a global function (D) that
should be maximized according to efficient selection of variables. The CCD design matrix
results in Table 2 show the maximum (561.936) and minimum (110.308) fluorescence intensity
for Cd(II). On the basis of desirability score of 0.92, maximum fluorescence intensity of 432
A.U. was obtained at optimized conditions, so the parameters set as follows: reaction time 25
min, concentration of T(4-NO2-P)P and Zn(II) 8.0 ×10-6 mol L-1 and 5.0 ×10-5 mol L-1
respectively and 298 K for temperature. The performance of three replicates at specified
optimum conditions showed a good agreement with predicted results and supported high
applicability of CCD for prediction of real behavior of Cd(II) sensor.
3.5 Fluorescence intensity of probe against different Concentrations of Cd2+
Concentration of Cd2+ shows prominent effect on emission intensity of the probe,
accompanying an increase in the concentration of Cd+2 in optimum conditions, with the peak
intensity of the maximum emission at 608 nm. As it has been shown in Fig. 8, there are a linear
change in fluorescence intensity with the addition of appropriate concentration of Cd (II). The
inset demonstrates that fluorescence intensity is proportional to the concentration of Cd(II) in
the range of 1.0×10-6-1.0×10-5 mol L-1.
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3.6. Analytical figures of merit
To evaluate practical applicability of the proposed cadmium turn-on sensor, linearity, limit
of detection, and relative standard deviation (RSD) were investigated. The calibration curve for
cadmium was linear from 1.0 × 10-6 to 1.0 × 10-5 mol L-1 with the coefficient of determination
(R2) of 0.994. The limit of detection (LOD) based on 3Sb/m definition (where m is the slope of
the calibration curve and Sb is the standard deviation of five blank measurements) was 2.76 ×10-7
mol L-1. Relative standard deviation (RSD %) of the method for determination of cadmium was
1.9% (n = 5).
3.7. Application of the proposed turn-on sensor to real samples
In order to evaluate the reliability and analytical applicability of the proposed turn-on sensor
for analysis of different matrices, the optimized method was applied for the determination of
cadmium in cosmetic, and personal care samples. Sample preparations of real samples were
performed as described in Section 2.3. For verification of the accuracy of the method, cadmium
was also determined in all the samples by FAAS, not presenting statistical difference between
results obtained. All these results are presented in Table 4. The nearness results of the two
methods (i.e. FAAS and spectrofluorometry) proves the well working of the synthesized probe as
a selective and sensitive sensor even in complex matrices and show that the sensing system has
great potential for quantitative determination of cadmium in different cosmetic, and personal
care samples.
4. Conclusion
Prevention of the effects of toxic elements, like cadmium, requires a complete monitoring in
real samples. Cosmetic and health products are one of widespread consumed products globally
and improper amount of cadmium in any product makes a big health related problems. We have
developed a new, highly sensitive and selective spectrofluorometric sensor for measuring the
amount of Cd ions over a wide range of foreign ions in various real samples with complex
matrices. For this purpose T(4-NO2-P)P was synthesized in higher yield than before, and used as
a turn-on sensor for the fast detection of trace amounts of the cadmium ions in organic media.
Optimum operating conditions that yield the maximum efficiency, determined by using response
surface methodologies (RSM). Central composite design was utilized to reveal quadratic and
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interaction terms, enabling us to choose more precisely the best experimental conditions for the
effective involved factors with minimal experimental trials. The practical ability of the proposed
turn-on sensor for the detection of cadmium ions in different cosmetic and health products
samples with complex matrices was tested and the satisfactorily results were obtained.
Acknowledgements
We are grateful to the research council of the University of Birjand for financial support.
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List of figures captions:
Fig. 1. UV-Vis spectrum of synthesized T(4-NO2-P)P, [T(4-NO2-P)P]=1× 10−4 mol L-1 in
chloroform.
Fig. 2. The molecular structure of the T(4-NO2-P)P.
Fig. 3. Fluorescence emission spectra of 1.0 × 10-5 mol L-1 of the T(4-NO2-P)P at λemi = 608 nm
in the presence of 8 × 10−5 mol L-1 solutions of various metal ions at 250C and in ethanol.
Excitation was done at λexc = 420 nm.
Fig. 4. Fluorescence response profile changes of 1.0 × 10-5 mol L-1 of T(4-NO2-P)P in the
presence of 8 × 10−5 mol L-1 solutions of various metal ions at 250C and in ethanol, at λexc = 420
nm.
Fig. 5. The proposed structure for the interaction of T(4-NO2-P)P with Cd(II); Sol. = solvent
molecule.
Fig. 6. Normal probability plot (NPP) for residuals.
Fig. 7. The 3D response surface plots for fluorescence intensity vs. a) concentration of the T(4-
NO2-P)P and temperature, (b) concentration of the T(4-NO2-P)P and time of reaction and (c)
temperature and time of response.
Fig. 8. Fluorescence intensity of probe against different concentrations of Cd2+ in optimum
conditions.
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Fig. 1
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Fig. 2
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Fig. 3
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Fig. 4
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Sol.
NH
N
N
Sol.
O
Cd
N
Sol.
O
HN
Sol.
Fig. 5
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Fig. 6
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Fig. 7 (a,b)
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Fig. 7(c)
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Fig. 8
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Table 1
Experimental factors and levels in the central composite design.
Factors
Unit
Notation
Range and Levels
-α
-1
0
+1
+α
Conc. T(4- NO2-P)P mol L-1
A
4.5 × 10-6
8.0 × 10-6
1.15 × 10-5
1.5 × 10-5
1.85 × 10-5
Temperature
Time
K
B
C
288
15
298
25
308
35
318
45
328
55
min
Conc.Zn(II)
mol L-1
D
2.5 × 10-5
5.0 × 10-5
7.5 × 10-5
1.0 × 10-4
1.25 × 10-4
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Table 2
Design matrix and the results of the central composite full factorial design.
Run
A
B
C
D
Flu. intensity
118.977
285.082
113.6
1
1.50 × 10-5
8.00 × 10-6
1.50 × 10-5
1.50 × 10-5
1.15 × 10-5
8.00 × 10-6
8.00 × 10-6
8.00 × 10-6
8.00 × 10-6
8.00 × 10-6
1.15 × 10-5
8.00 × 10-6
1.15 × 10-5
1.50 × 10-5
1.50 × 10-5
1.50 × 10-5
8.00 × 10-6
1.50 × 10-5
1.50 × 10-5
1.15 × 10-5
1.15 × 10-5
1.15 × 10-5
1.15 × 10-5
4.50 × 10-6
1.85 × 10-5
1.15 × 10-5
1.15 × 10-5
1.15 × 10-5
1.15 × 10-5
1.15 × 10-5
318
298
318
318
308
298
298
298
318
318
308
318
308
298
298
298
318
298
318
308
308
308
308
308
308
308
308
288
328
308
25
25
45
45
35
45
25
45
25
45
35
45
35
45
25
25
25
45
25
35
15
35
35
35
35
35
55
35
35
35
5.00 × 10-5
1.00 × 10-4
1.00 × 10-4
5.00 × 10-5
7.50 × 10-5
5.00 × 10-5
5.00 × 10-5
1.00 × 10-4
1.00 × 10-4
1.00 × 10-4
7.50 × 10-5
5.00 × 10-5
7.50 × 10-5
5.00 × 10-5
1.00 × 10-4
5.00 × 10-5
5.00 × 10-5
1.00 × 10-4
1.00 × 10-4
7.50 × 10-5
7.50 × 10-5
2.50 × 10-5
1.25 × 10-4
7.50 × 10-5
7.50 × 10-5
7.50 × 10-5
7.50 × 10-5
7.50 × 10-5
7.50 × 10-5
7.50 × 10-5
2
3
4
128.227
171.294
414.188
442.174
292.779
408.215
420.925
180.963
430.758
230.978
154.016
110.308
160.232
446.408
118.992
122.971
206.156
212.131
205.16
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
190.786
561.963
114.496
220.285
217.414
384.688
190.079
230.409
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Table 3
The ANOVA results of CCD for fluorometric detection of Cd(II).
p-value
Prob > F
< 0.0001
< 0.0001
0.4521
Source
Sum of Squares DF a Mean Square
F -value
Model
A
4.424 × 10 5
3.770 × 10 5
1304.02
4.43
14
1
1
31599.13
3.770 × 10 5
1304.02
4.43
14.50
172.98
0.60
Significant
B
C
1
2.034 × 10 -3 0.9647
D
AB
AC
AD
8469.63
6883.03
40.88
3333.50
13.62
1
1
1
1
8469.63
6883.03
40.88
3333.50
13.62
3.89
3.16
0.0688
0.0973
0.8930
0.2366
0.019
1.53
BC
1
6.247 × 10 -3 0.9381
BD
CD
A^2
B^2
C^2
D^2
5806.06
227.42
29937.37
11331.85
129.53
1
1
1
1
1
1
5806.06
227.42
29937.37
11331.85
129.53
2.66
0.10
13.73
5.20
0.059
0.052
0.1249
0.7515
0.0023
0.0388
0.8109
0.8234
112.67
112.67
Residual
Lack of fit
Pure error
Cor Total b
30515.13
28308.04
2207.08
4.731 × 10 5
14
10
4
2179.65
2830.80
551.77
5.13
0.0645 Not significant
29
a Degree of freedom.
bTotals of all information corrected for the mean.
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Table 4
Determination of Cd(II) in cosmetic, and personal care samples by proposed fluorometric and FAAS methods.
Amount of Cd(II) (mol L-1)
Real sample
Fluorometric
3.06 × 10-6
1.46 × 10-6
0.80 × 10-6
FAAS
Lipstick
Hair Color
Makeup Cream
2.92 × 10-6
1.41 × 10-6
0.73 × 10-6
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Graphical Abstract
Graphical Abstract Synopsis
In this study for the first time, a porphyrin ring which bounded to four deactivating NO2 groups
was used as a “turn-on” fluorescence sensor. The developed sensor showed high selectivity,
giving sensitive response toward cadmium metal ion and detecting micro-molar concentrations.
This fluorescent probe could be used to measure the amount of cadmium ions in cosmetic and
health product samples.
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Highlights
 A new T(4-NO2P)P has been synthesized and used as a turn-on fluorescence sensor.
 Turn-on fluorescence sensor showed very high selectivity to Cd(II) ions.

The proposed sensor was applied for the detection of Cd(II) in cosmetic samples.
 Fluorescent probe optimization was conducted by multivariate chemometrics method.
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