Anal. Method Environ. Chem. J. 3 (3) (2020) 5-17
Research Article, Issue 3
Analytical Methods in Environmental Chemistry Journal
Journal home page: www.amecj.com/ir
AMECJ
Speciation of selenium (IV, VI) in urine and serum of thyroid
patients by ultrasound-assisted dispersive liquid-liquid
microextraction
Elham Mosafayian Jahromy
a
and Negar Motakef Kazemi
a,*
a
Department of Medical Nanotechnology, Faculty of Advanced Sciences and Technology, Tehran Medical Sciences,
Islamic Azad University, Tehran, Iran
ABSTRACT
In-vitro speciation of inorganic selenium (Se
IV
and Se
VI
) in serum
blood and urine of hyperthyroidism and hypothyroidism patients
based on isopropyl 2-[(isopropoxycarbothiolyl) disulfanyl] ethane
thioate (IICDET) as a complexing agent were studied by ultrasound-
assisted dispersive liquid-liquid bio-microextraction procedure (USA-

of [C
8
MIM][PF
6


shacking, the Se (IV) ions were complexed by IICDET and extracted

by centrifuging and inorganic selenium (Se
IV
) in remained samples
was determined by electro thermal atomic absorption spectrometry
(ET-AAS) after back extraction of Se (IV). As speciation, the Se (VI)
        
O
C) and the total Se(T-
          
by difference of T-Se and Se (IV). After optimized conditions, the
enrichment factor (EF), Linear range and limit of detection (LOD)





in serum and urine samples respectively. The results showed
us, the concentration of selenium was decreased in thyroid patients
as compared to healthy peoples. The validation of methodology was

Keywords:
Selenium,
Inorganic speciation,
Serum and urine,
Isopropyl [(IsopropoxyCarbothiolyl)
Disulfanyl] Ethane Thioate,
Ultrasound-assisted dispersive liquid-
liquid bio-microextraction,
ARTICLE INFO:




*Corresponding Author: Negar Motakef Kazemi
Email: negar.motakef@gmail.com

------------------------
1. Introduction
Selenium is an essential trace element in humans.
The soluble selenium compounds can be easily
absorbed through the lungs and the gastrointestinal
tract. Selenium is mainly excreted in human urine
. When the exposure is very high it can also be
excreted in exhaled air as dimethylselenide vapor
(DMSe). Normal selenium concentrations in serum
and urine are dependent on daily intake, which may
vary considerably in different parts of the world but
       

  
g

creatinine, respectively . The concentration

exposure. The relationship between the intensity of
exposure and selenium concentration in urine has not
been established yet. It seems that the concentration
        
short-term exposure, whereas the selenium content
     
6
Anal. Method Environ. Chem. J. 3 (3) (2020) 5-17
[6]. Measuring selenium in blood or urine gives
some information on selenium status. Currently it is

overexposure. Since the available data concerning the
health risk of long-term exposure to selenium and the
relationship between potential health risk and levels
in biological media are too limited. So, the biological
threshold value for Se wasn’t reported . The thyroid
is the organ with the highest selenium content per gram

The value of selenium supplementation in
autoimmune thyroid disorders has been emphasized.
Most authors attribute the effect of supplementation
on the immune system to the regulation of the
production of reactive oxygen species and their
metabolites . The mechanism and role of

was reported  
disease and in pregnant women with anti-TPO
antibodies, selenium supplementation decreases anti-
thyroid antibody levels and improves the ultrasound
structure of the thyroid gland . Although clinical

disease, they are very interesting for pregnant
    
decreases the percentage of postpartum thyroiditis
     
selenium supplementation results in euthyroidism
being achieved more rapidly and appears to have a
     
. A risk of diabetes has been reported following
long-term selenium supplementation, but few data
are available on the side effects associated with such
supplementation and further studies are required.
One of the diseases that affect the thyroid gland is
subclinical hypothyroidism, which is characterized
by elevated serum levels of thyroid-stimulating
     

 
thyroid hormones may contribute to atherosclerotic
events and an increase in cardiovascular-related
mortality . Also, observational longitudinal
studies have shown an inverse association between
selenium exposure and risk of some cancer types
     . It is estimated that
     
general population and is more common in women
than in men. In Brazil, an epidemiological study
in elderly reported that prevalence of subclinical
     
contains high levels of selenium (Se) and expresses
a variety of selenoproteins that are involved in
protection of oxidative stress and metabolism of
     
impairs regular synthesis of selenoproteins and

in serum and urine must be evaluated and determined
by favorite techniques. The different methods such
     ,
electrothermal atomic absorption spectrometry ,
liquid chromatography and liquid chromatography
inductively coupled plasma mass spectrometry (LC
and LC-ICP- MS)  and high-performance
liquid chromatography coupled to hydride generation
 were used
for Se determination in different human and water
samples. A sample preparation is required to extract
metals ions in different biological samples. The sample
preparation such as microextraction techniques ,
suspended dispersive solid phase microextraction
[26], ultrasonic assisted dispersive liquid-liquid
microextraction method  and ultrasound assisted-
ionic liquid-solid phase microextraction [28] were used
for extraction metals in human samples. In this study,
the mixture of hydrophobic ionic liquid of [C
8
MIM]
[PF
6
], IICDET ligand and acetone was used for
selenium speciation /extraction based on ultrasound-
assisted dispersive liquid-liquid bio-microextraction
procedure (USA-DLLMBE) and determined by ET-
AAS. The Se (IV) ions were complexed by IICDET
     
was obtained by total determination of selenium.

standard samples and ICP-MS.
2. Experimental
2.1. Instrument and Reagents
The electrothermal atomic absorption

Speciation of selenium (IV, VI) in human urine and serum Elham Mosafayian Jahromy et al

used for the validation and determination of selenium






,
respectively. The linear range was achieved for peak
        
manual book of ET-AAS, the Se determination was

with auto-sampler in three steps of drying, ashing,
and atomization for Se. The ICP-MS (Perkin Elmer,
USA) as ultra-trace analysis with high sensitivity was
used for determining of Se(IV) and Se(VI) in human





). The Metrohm

       
      
        

rpm speeds (Thermo, USA). An ultrasonic bath was
used for blood and urine samples with heat controller
  
o
C (Thomas, USA). The standard
solution of Se (VI, VI) was purchased from Merck



. The different concentration of Selenium
was prepared by dilution of deionized water (DW)
and ultrapure water was purchased from Millipore
  


6
], CAS
N: ). Isopropyl 2-[(isopropoxycarbothioyl)

     

(CO)
2
S


COONa) and


of reagents such as polyoxyethylene octyl phenyl


acetone, and ethanol were purchased from Sigma

2.2. Preparation of human samples
         
mol L


solution for at least one day and
then washed for ten times with ultrapure water.
As low concentrations of Se(IV) and Se(VI) in
human serum, blood and urine samples, the cations
or anions contamination at any stage of sample
preparation, saving and analytical processes can be

as anticoagulants for human blood samples into

O
C for two


serum, blood and urine samples were collected from
     
        

     
guiding physicians in human body research was
considered by project of Azad university (AZAD

      
protected the life and health of the human subject.
2.3. Synthesis of IICDET ligand
 

mol of potassium O-isopropyl

         


mol of iodine solution and potassium



2
Cl
2

aqueous Na
2
S
2
O

was dried and evaporated with powder anhydrous
calcium chloride Ca Cl
2
  
     
recrystallization in hexane. A pale yellowish crystal
of isopropyl 2-[(isopropoxycarbothiolyl) disulfanyl]

structure and isopropyl 2-[(isopropoxycarbothiolyl)

spectroscopic methods .

).
     
    

  
     
       
        

