Two new potentiometric methods for determination of titanium in pure form and in its pharmaceutical form are developed. In the first method, new modified carbon paste electrode based on(SAPD) as a chemical modifier. The construction of carbon paste electrodetitanium ion-selective electrode and its use in the potentiometric determination of titanium in pharmaceutical preparations and orthodontic cages is described. The electrode displays a linear log [Ti3+] versus EMF response over a wide concentration range of 4.1×10−7 to 1.2×10−3 with nernstian slope of 19.1±0.1 mV/decade with limit of detection 1.1×10−7 over the pH range 3.8–7.8; a response time of <10 s; and use for at least 3 months without any significant potential divergence the presence of the complex Ti(OH)2+ ion explains the slope of the response curve. The proposed sensor shows reasonable discrimination ability. The modified electrode was applied as indicator electrode to determine Ti(III) in aqueous samples with satisfactory results

Mahmoud Ebrahimi

Mohammad Reza Abedi

Mohammad Reza Bozorgmehr

Sara Sahebnasagh

Journal of Research in Medical and Dental Science

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Journal of Research in Medical and Dental Sciences 
Volume 5, Issue 3, Page No: 88-92 
Copyright CC BY-NC-ND 4.0 
Available Online at: www.jrmds.in 
eISSN No. 2347-2367: pISSN No. 2347-2545 
 
 
Journal of Research in Medical and Dental Science | Vol. 5 | Issue 3 | September 2017 88 
 
Determination of titanium in orthodontic with modified graphene 
paste electrode and ionic liquid by potentiometric method 
 
Sara Sahebnasagh1, Mahmoud Ebrahimi1*, Mohammad Reza Bozorgmehr1, 
Mohammad Reza Abedi2 
 
1Department of Applied Chemistry, Mashhad Branch, Islamic Azad University, Mashhad, 
Iran 
2Department of Applied Chemistry, Quchan Branch, Islamic Azad University, Quchan, Iran 
 
DOI: 10.24896/jrmds.20175314 
ABSTRACT 
 
Two new potentiometric methods for determination of titanium in pure form and in its pharmaceutical form 
are developed. In the first method, new modified carbon paste electrode based on(SAPD) as a chemical 
modifier. The construction of carbon paste electrodetitanium ion-selective electrode and its use in the 
potentiometric determination of titanium in pharmaceutical preparations and orthodontic cages is 
described. The electrode displays a linear log [Ti3+] versus EMF response over a wide concentration range of 
4.1×10−7 to 1.2×10−3 with nernstian slope of 19.1±0.1 mV/decade with limit of detection 1.1×10−7 over the 
pH range 3.8–7.8; a response time of <10 s; and use for at least 3 months without any significant potential 
divergence the presence of the complex Ti(OH)2+ ion explains the slope of the response curve. The proposed 
sensor shows reasonable discrimination ability. The modified electrode was applied as indicator electrode to 
determine Ti(III)  in aqueous samples with satisfactory results. 
 
Keywords: Carbon paste; Potentiometry; 2-AAINH; Titaniuml, orthodontic cages 
HOW TO CITE THIS ARTICLE: Sara Sahebnasagh, Mahmoud Ebrahimi, Mohammad Reza Bozorgmehr, Mohammad Reza Abedi, 
Determination of titanium in orthodontic withy modified graphene paste electrode and ionic liquid by potentiometric method, J Res 
Med Dent Sci, 2017, 5 (3): 88-92, DOI: 10.24896/jrmds.20175314 
Corresponding author: Mahmoud Ebrahimi 
e-mailm.ebrahimi@mshdiau.ac.ir 
Received: 12/06/2017 
Accepted: 21/08/2017 
 
INTRODUCTION 
 
The paint, pigment, paper and pulp industries 
discharge very high amount of titanium. 
Titanium is a metal that has been used in 
various and varied medical applications for 
about 40 years. Although many biomaterials 
have come and gone during this period, titanium 
is one of the few that has seen its uses and 
reputation enhanced over the years. There are 
various methods for the determination of 
titanium utilizing a number of ligands such 
aspyridylazoresorcinol [1], 5-
bromopyridylazodiethylaminophenol [2] 
thiazolylazoresorcinol with mordant red 19 [3], 
solochrome violet relay services (RS), [4]  
Beryllon (III) and cupferron [5-6].  
 
Determination of titanium by adsorption 
voltammetry with 2-(5-bromo-2-
pyridylazo)-5-(diethylamino)-phenol. 
Carbon nanostructure materials, due to their 
extremely large surface area and excellent 
adsorption capacity, have been successfully 
used as adsorbent in SPE and SPME for trapping 
or separation of some organic compounds [7]. 
Graphene (G), which was discovered in 2004, is 
a relatively new form of carbon made of a single 
layer of atoms arranged in a honeycomb-shaped 
lattice and has attracted tremendous attention 
in recent years [8,9]. It is considereda s the basic 
building block of all the graphitic (including 
carbon nanotubes, graphite and fullerene C60) 
[10]. In addition to being the principal 
component of most carbon based nanomaterials, 
G also exhibits excellent mechanical, electrical, 
thermal, optical properties and very high 
specific surface area. Since the large delocalized 
electron system of G can form a strong _-
stacking interaction with the benzene ring 
[11,12], it might be also a good candidate as an 
adsorbent for the extraction of benzenoid form 
compounds. The introduction of magnetic 
properties into G would combine the high 
adsorption capacity of G and the separation 
convenience of magnetic materials. 
Mahmoud Ebrahimi et al J Res Med Dent Sci, 2017, 5 (3):88-92 
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Journal of Research in Medical and Dental Science | Vol. 5 | Issue 3 | September 2017 89 
 
On the other hand, the rolled version of 
graphene, carbonnanotube (CNT) has excellent 
mechanical, electrical, catalytic and 
electrocatalytic properties [12]. Enormous 
amount of work has` nanotubes(SWCNT) for 
electrochemical applications [13]. Pristine CNTs 
are highly hydrophobic and as a result it is 
impossible to prepare its stable aqueous 
dispersion [14].Ionic  liquid  (IL),  another  
material,  due  to  its wide  electrochemical  
windows,  high  ionic  conductivity  and  good 
solubility  has  been  widely  applied  in  the  
fields  of  analytical  chemistry  and  
electrochemical  sensors[ 15-17]. The 
acknowledged advantages of these room 
temperature ionic liquids (RTILs) include good 
chemical and thermal stability, almost negligible 
vapor pressure, good ionic conductivity, and 
wide electrochemical windows etc [18-22].  
 In this paper the preparation of a new Ti+3 ion 
selective electrode was described, based on 
graphene paste electrode with SAPD as a 
selector element and ionic liquid as modifier. 
The modified electrode was successfully used as 
an indicator for potentiometric determination of 
Ti (III)in aqueous sample. 
 
MATERIALS AND METHODS 
 
The room temperature ionic liquid, 1-butyl-3-
methylimidazolium tetrafluoroborate ([BMIM] 
[BF4]) was acquired  from Spectrochem. All 
analytical reagent grade chemicals and distilled 
water were used for preparing all aqueous 
solutions. The reagents in this experiment 
including TiCl3, NaOH and HCl were purchased 
from Merck. All solutions were prepared from 
distilled water. (65%, Merck), HCl(37%, Merck) 
and Ethanol (98%) were used as received. 
 
Apparatus  
An Ag/AgCl electrode (saturated KCl) was used 
as the counter and reference electrodes 
respectively. Modified graphene paste electrode 
(GPE) was applied as a working electrode. All 
experiments were usually directed at room 
temperature. A Metrohm model 780 pH-meter 
(Herisau, Switzerland) with a combined glass 
electrode was utilized for pH controlling, and 
also a Heidolph type of stirrer (MR 2000, 
Kelheim, Germany) was applied for stirring the 
solutions. 
 
Electrode Preparation 
General procedure to prepare the carbon paste 
electrode was as follows: Different amounts of  
nanoparticle with an appropriate amount of 
graphite powder, ionic liquid, paraffin oil and 
plasticizer(DBP) were thoroughly mixed. After 
homogenization of the mixture, the paste was 
thoroughly packed into the teflone tube and an 
electrice wire was inserted into the opposite 
end of the GPE to set up electrical contact. The 
external surface of the carbon paste was 
smoothed with soft paper. A new surface was 
produced by scraping out the old surface and 
replacing the new carbon paste. The electrode 
was finally conditioned for 12 h by soaking it in 
a 1.0×10-4mol L-1 chromium (VI)solution [23-
25]. 
 
RESULTS AND DISCUSSION 
 
Graphene paste electrode composition 
The sensing element of a potentiometric ion-
selective electrode has important role in 
selectivity behavior of the electrode. The 
influence of the percent of materials in the 
carbon paste composition was investigated and 
the results are summarized in Table 1. 
 
Measuring range and detection limit 
The response of the optimal modified Ti3+ 
carbon paste electrode (no.2) was tested across 
Ti3+ ion concentration range of 3.1×10-2-4.9×10-
10 mol L-1. The applicable range of the proposed 
sensor extends from 1.0×10-5 to 1.0×10-1 mol L-1 
as seen in Table 1. 
 
pH effect on the electrode response 
In order to study the effect of pH on the 
response of the optimal modified Cr6+ sensor 
(no.6), the potential was measured for a fixed 
concentration of Ti3+ ion solutions at different 
pH values. The pH was varied from (1-8) by 
addition of concentrated HNO3 or NaOH. The 
change in potential as a function of pH is shown 
in Fig.1. The potential was constant and 
quantitative in the pH range of 1.5–5. At pH< 1.5, 
the electrode response increased rather 
irregularly with increasing analyte acidity. At 
such high acidic solutions, the observed increase 
in potential indicates that the protonated 
titanium possesses a poor response to the Ti3+ 
ions. The pH dependence of the electrode 
potential for the sensors is tested in presence of 
4.0×10−4 mol L-1 titanium (III) concentration 
after sensor conditioning. The ionic strength in 
test solution is maintained constant with 0.1 
mol L-1 NaNO3.  
 
 
 
 
 
 
Mahmoud Ebrahimi et al J Res Med Dent Sci, 2017, 5 (3):88-92 
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Journal of Research in Medical and Dental Science | Vol. 5 | Issue 3 | September 2017 90 
 
Table 1. The optimization of the Graphen paste ingredients 
 
Dynamic linear range Composition of graphene Paste (wt.%) NO 
Recovery Plasticizer Graphene Powder Ionic liquid Graphene 
3.1×10-3-4.0×10-8 94.5 11 72 5 12 1 
3.1×10-2-5.2×10-10 98.3 11 71 5 13 2 
1.4×10-2-5.3×10-8 94.3 12 70 8 10 3 
3.0×10-3-5.4×10-8 91.2 14 70 6 10 4 
5.1×10-2-5.5×10-8 93.1 10 71 7 12 5 
3.1×10-2-4.9×10-10 98.3 10 72 6 12 6 
2.2×10-2-5.5×10-6 98 4 76 7 13 7 
43.0×10-2-2.0×10-7 96.2 5 75 5 15 8 
3.5×10-3-3.1×10-10 94.4 6 74 7 13 9 
5.3×10-4-4.2×10-6 94.0 8 75 5 12 10 
 
 
 
 
Fig. 1 Effect of pH on the potential response of the Ti3+ graphene paste electrode in the test solution of Ti3+ ion (10-3 mol L-1) 
 
 
 
Fig. 2 Dynamic response time of the proposed carbon paste electrode (no.6) 
 
Table 2:  Selectivity coefficients of various interfering species for proposed sensor (no.6) 
 
Interfering ions  Interfering ions  
Cu2+ 5.1×10-3 Cd2+ 1.3×10-3 
Mg2+ 3.2×10-3 Fe3+ 2.1×10-2 
Ca2+ 2.5×10-2 Sr2+ 1.1×10-3 
 
 
The pH values are adjusted by adding small 
volumes of diluted nitric acid or sodium 
hydroxide solutions. The potential value is read 
and the solution pH is measured when the 
electrode response is stabilized. The results for 
solutions containing titanium (III) are shown in 
Fig. 1. The GPE sensible is pH changes, in 
presence of Ti(III), with a slope of 19.1mVpH−1 
linear behavior. 
 
 
Response time 
Response time is an important factor for any 
sensor. For electrochemical sensors, this 
parameter is evaluated by measuring the 
average time required to achieve a potential 
within ±0.1 mV of the final steady-state 
potential upon successive immersion of a series 
of interested ions, each having a ten-fold 
difference in concentration. The measurements 
of potential versus time were carried out with 
the Ti (III) solutions from lower (1.0×10-8 M) to 
300
400
500
600
700
0 1 2 3 4 5 6 7 8 9
E
(m
V
)
pH
Mahmoud Ebrahimi et al J Res Med Dent Sci, 2017, 5 (3):88-92 
__________________________________________________________________________________ 
Journal of Research in Medical and Dental Science | Vol. 5 | Issue 3 | September 2017 91 
 
higher (1.0×10-2 M) concentrations (Fig.2). For 
the proposed modified Cr6+ sensor, the response 
time was less than 9s. 
 
Selectivity 
Selectivity is the most important characteristic 
of any sensor, and describes an ion selective 
electrode’s specificity toward the target ion in 
the presence of interfering ions, the 
potentiometric selectivity coefficients of the 
proposed carbon paste electrode were 
evaluated by separate solution method (SSM) 
[26] and the results are depicted in Table 2. 
 
 
The potential of a cell comprising an ion-
selective electrode and a reference electrode is 
measured with two separate solutions, one 
containing the ion (i) at the activity ai , the other 
one containing the ion( j)at the same activity ai = 
aj. If the measured values are Ei and Ej , 
respectively, the value of is calculated from the 
equation: 
 
	
 =  − 2.303  + 	 
 !"#
 !$#%&/%( 
 
These results seem to indicate that interference 
effects upon the performance of the electrode 
assembly are negligible. 
 
Analytical applications 
The proposed sensor was found to work well 
under laboratoryconditions. It is clear that the 
amount of Ti(III) ions can be 
accuratelydetermined using the proposed 
sensor. 
 
Determination of mercury in spiked real 
sample 
One gram of the dry and clean orthodontic cages 
sample was dissolved in minimally concentrated 
nitric acid and the solution was transferred to a 
100 ml of calibrated flask and diluted to the 
mark with distilled water. The pH of solution 
was controlled and the measurement was done. 
With the use of sensor’s calibration curve, the 
nickel content in our sample, obtained from 
triplicate measurement with electrode.To assess 
the applicability of the proposed sensor to real 
samples,Ti(III) was measured in orthodontic 
cage. Each sample was analyzed in triplicate, 
using this sensor by the standardaddition 
method. The results, in Table 3, show an average 
recoveryof 92.6% with relative standard 
deviation (RSD) of 2.43% andindicates the 
utility of the proposed electrode. 
 
Table3. Recovery of copper ions from different water 
samples 
 
Sample 
Ti3+ 
added 
Ti3+founded RR% 
RSD% 
(n=3) 
Sample 
1 
3×10-5 M 2.66×10-5 91.5 3.17 
Sample 
2 
3×10-5 M 2.44×10-5 92.9 2.91 
 
CONCLUSION 
 
In this study, a new chemicallymodified carbon 
paste electrodebased on N,N_-
bis(salicylaldehyde)-phenydiamine as 
ionophore and ionic liquid was used for Ti(III) 
determination. The electrodeshows high 
sensitivity, reasonable selectivity, fast 
staticresponse, long term stability and 
applicability over a wide concentrationrange 
(3.1×10-2-4.9×10-10). The modified electrode 
was applied as indicator electrode in 
potentiometric method andsuccessfully used to 
determine titanium(II) in real samples 
withsatisfactory results. 
 
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Determination of titanium in orthodontic with modified graphene paste electrode and ionic liquid by potentiometric method

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Determination of titanium in orthodontic with modified graphene paste electrode and ionic liquid by potentiometric method

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