Deep eutectic liquid organic salt was used as the solvent and a liquid phase microextraction (DES–LPME) combined with electrothermal atomic absorption spectrometry (ETAAS) was developed for ...separation, preconcentration and determination of lead and cadmium in edible oils. A 4:1 mixture of deep eutectic solvent and 2% nitric acid (200µL) was added to an oil sample. The mixture was vortexed and transferred into a water bath at 50°C and stirred for 5minutes. After the extraction was completed, the phases were separated by centrifugation, and the enriched analytes in the deep eutectic solvent phase were determined by ETAAS. Under optimized extraction conditions and for an oil sample of 28g, enhancement factors of 198 and 195 and limits of detection (defined as 3Sb/m) of 8 and 0. 2ngkg−1 were achieved for lead and cadmium respectively. The method was successfully applied to the determination of lead and cadmium in various edible oils.
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•The first report on the use of deep eutectic liquid organic salt as solvents for LPME.•Application of DES–LPME for extraction/preconcentraion of metal ions from edible oils.•Development of a simple and sensitive method for det. of traces of Pb and Cd in edible oils.
A simple, rapid and eco-friendly deep eutectic solvent-modified magnetic nanoparticles extraction method has been reported for ligand-less separation/preconcentration of lead(II) and cadmium(II) for ...the first time. The metal ions interact with the deep eutectic solvent adhering to the magnetic nanoparticles. Trapped analytes can be easily desorbed with 1.0 M nitric acid and determined by flame atomic absorption spectrometry. The effects of pH value, type of deep eutectic solvent, sample volume, nature and concentration of desorbing solution, ionic strength and extraction time on the extraction were optimized. Under the optimized experimental conditions, the detection limits (defined as 3S
b
/m) were 0.4 and 0.1 μg L
−1
and the linear dynamic ranges were 2 to 250 μg L
−1
and 0.5 to 30 μg L
−1
for lead and cadmium, respectively. The relative standard deviations for six replicate measurements at 150 and 20 μg L
−1
levels of lead and cadmium were 1.8 and 2.1 %, respectively. A sample volume of 60 mL resulted in a preconcentration factor of 100. The sorbent showed high capacity for lead (25.0 mg g
−1
) and cadmium (23.7 mg g
−1
). The method was successfully applied to the determination of lead and cadmium in soil, hair and several water samples.
Graphical Abstract
Deep eutectic solvent (DES) and Fe
3
O
4
nanoparticles were added to the sample solution, and the DES containing the target ions was trapped on the sorbent and separated by means of a strong magnet. The analytes were desorbed by nitric acid, and the extracted metal ions were then directly submitted to FAAS for quantification
A novel sorbent consisting of magnetic oxidized nanocelluloses modified with graphene quantum dots was prepared and used for the separation and preconcentration of dopamine. The eluted dopamine from ...the sorbent was determined by a designed chemiluminescence system containing luminol, H
2
O
2
, Fe
3+
, and graphene quantum dots doped with nitrogen and phosphorus. Graphene quantum dots cause an increase in the intensity of the chemiluminescence system of luminol-H
2
O
2
, but the presence of Fe
3+
ions in this system decreases its intensity because of the sorption of the Fe
3+
ions on the surface of P, N-graphene quantum dots. However, the addition of dopamine resulted in the retrieval of P, N-graphene quantum dots, as well as the chemiluminescence intensity, due to the formation of its complex with Fe
3+
. The sorbent made of magnetic oxidized nanocelluloses modified with graphene quantum dots was characterized by various analytical techniques, and the effective parameters on the extraction of dopamine were investigated and optimized. Under the optimized conditions, the method displayed good linearity in the concentration range 0.25–17.5 µg L
−1
for dopamine (
R
2
= 0.9918) with a limit of detection of 0.054 µg L
−1
. The intra- and inter-day relative standard deviations at a 10.0 µg L
−1
concentration level of dopamine (
n
= 6) were 2.6 and 4.1%, respectively. This method was successfully applied to the extraction and determination of dopamine in human serum and urine samples.
Graphical abstract
A chemometric-assisted kinetic spectrophotometric method has been developed for simultaneous determination of ascorbic acid (AA), uric acid (UA), and dopamine (DA). This method relies on the ...difference in the kinetic rates of the reactions of analytes with a common oxidizing agent, tris(1,10-phenanthroline) and iron(III) complex (ferritin, Fe(phen)33+) at pH 4.4. The changes in absorbance were monitored spectrophotometrically. The data obtained from the experiments were processed by chemometric methods of artificial neural network (ANN) and partial least squares (PLS). Acceptable techniques of prediction set, randomization t test, cross-validation, and Y randomization were applied for the selection of the best chemometric method. The results showed that feedforward artificial neural network (FFANN) is more efficient than the other chemometric methods. The parameters affecting the experimental conditions were optimized, and it was found that under optimal conditions Beer’s law is followed in the concentration ranges of 4.3–74.1, 4.3–78.3, and 2.0–33.0μM for AA, UA, and DA, respectively. The proposed method was successfully applied to the determination of analytes in serum and urine samples.
A magnetic molecularly imprinted polymer (MMIP) was fabricated for captopril by surface polymerization of Fe
3
O
4
@SiO
2
nanoparticles using a new functional monomer of ...N-(allylcarbamothioyl)-2-chlorobenzamide. It was then employed as a selective nanosorbent for dispersive magnetic micro solid phase extraction (DM-μ-SPE) of captopril from biological and wastewater samples. To characterize the physicochemical properties of the MMIP, different analytical methods such as the vibrating sample magnetometer, field emission scanning electron microscopy, Brunauer-Emmett-Teller, and Fourier transform infrared spectroscopy were utilized. To gain the maximum extraction recovery of captopril, the influence of various operating conditions was investigated and experimental settings optimized. After the extraction step, the concentration of captopril was measured by UV-Vis spectrophotometer at 245 nm. The assessments demonstrated that the MMIP provides higher extraction efficiency in comparison to magnetic non-imprinted polymer, suggesting the establishment of selective recognition binding sites at the MMIP surface. The method depicted desirable figures of merit of a low detection limit of 0.16 μg L
-1
, a limit of quantification of 0.50 μg L
-1
, a linear dynamic range of 0.50–22.0 μg L
-1
, and an acceptable preconcentration factor of 333. The magnetic MIP was successfully employed for preconcentration and extraction of trace amounts of captopril in real samples, such as human blood serum, urine, and wastewater samples, with recoveries in the range 95.7 to 102.6% and relative standard deviations < 5%.
Graphical abstract
A simple, sensitive, and selective fluorometric method based on graphene quantum dots and Hg
2+
is presented for the determination of tetracycline. The fluorescence emission of graphene quantum dots ...at 463 nm decreased in the presence of Hg
2+
ions due to its electrostatic interaction with the negatively charged surface of quantum dots at pH = 8.0. The addition of tetracycline to this system resulted in the retrieval of the fluorescence emission of the graphene quantum dots proportional to the tetracycline concentration. This is because of the interaction between tetracycline and Hg
2+
that results in the release of the quantum dots' surface. Under the optimized conditions, the calibration curve indicated good linearity in the range of 2.0–44.0 nmol L
−1
with a detection limit of 0.52 nmol L
−1
for tetracycline. The designed nanoprobe was capable of the determination of tetracycline in serum and urine samples.
Solidified floating organic drop microextraction (SFODME) was successfully used as a sample preparation method for graphite furnace atomic absorption spectrometry (GFAAS). 20
μL of 1-undecanol ...containing dithizone as the chelating agent (2
×
10
−4
mol
L
−1) was transferred to the water samples containing lead ions, and the solution was stirred for the prescribed time. The sample vial was cooled in an ice bath for 5
min. The solidified extract was transferred into a conical vial where it melted immediately, and then 10
μL of it was analyzed by GFAAS.
Factors that influence the extraction and complex formation, such as pH, concentration of dithizone, extraction time, sample volume, and ionic strength were optimized. Under the optimized conditions, a good relative standard deviation of ±5.4% at 10
ng
L
−1 and detection limit of 0.9
ng
L
−1 were obtained. The procedure was applied to tap water, well water, river water and sea water, and accuracy was assessed through the analysis of certified reference water or recovery experiments.
The first dual-modality highly intensive fluorescent and colorimetric nanoprobe for Fe
3+
ions and histidine is reported. The carbon dots doped by nitrogen and sulfur (N,S-CDs) prepared by the ...one-pot hydrothermal method have an excitation/emission wavelength of 320/420 nm with 56% quantum yield. N,S-CDs exhibit strong visible fluorescence with high stability at pH ~ 7.0. The fluorescence intensity of the N,S-CDs is quenched in the presence of Fe
3+
ions which are recovered upon the addition of histidine. The addition of Fe
3+
ions also induces a color change from yellow to red. Using colorimetric determination, Fe
3+
and histidine exhibited linearity in the range 75–675 and 100–375 μmol L
−1
, respectively, while with fluorometric determinations the dynamic range was 0.1–275 and 0.1–3 μmol L
−1
for Fe
3+
and histidine, respectively. The limits of detection were 19 nmol L
−1
and 0.03 μmol L
−1
using fluorometry and 20 μmol L
−1
and 24.2 μmol L
−1
using colorimetry, for Fe
3+
and histidine respectively. The relative standard deviations (
n
= 5) for Fe
3+
(10 μmol L
−1
) and histidine (1 μmol L
−1
) using fluorometry were 4.6 and 7.3% and using colorimetry at 100 μmol L
−1
of Fe
3+
and 150 μmol L
−1
of histidine were 3.2 and 5.6%, respectively. The developed fluorometric method was applied for the determination of Fe
3+
and histidine in various foods and biological fluid samples as well as intracellular imaging of iron. The accuracy of the method for iron determination was confirmed by the analysis of certified reference materials (wheat flour, tomato leaves, and whole milk powder) and quality control materials (whole milk powder, serum, and urine), whereas for histidine, the accuracy was determined by recovery experiment and independent analysis. Good recovery values in ranges of 92–96% and 94–98% were achieved for Fe
3+
and histidine, respectively.
Graphical abstract
A pH-sensitive nano-graphene oxide (nGO)-based delivery system is designed for Cur delivery to MCF cancerous cells. Cur is loaded on the synthesized nGO (Cur-nGO) and decorated by bovine serum ...albumin (BSA) to improve its biostability, protect the Cur from undesired loss and provide the carboxylic functional groups for aptamer conjunction (Cur-nGO-BSA). Finally, the Cur-nGO-BSA was functionalized with AS1411 aptamer and characterized by various methods. The drug loading and loading efficiency of the designed system are 8.9% and 78.9%, respectively. The loaded drug is preferably released in acidic media at in-vitro studies. The MTT test on MCF7 as positive and SKBR3 as negative nucleolin cancer cells revealed that the Cur-nGO-BSA can inhibit their growth while AS1411 aptamer-functionalized nano-carrier showed an improved efficiency toward MCF7 cells due to the significant affinity of the aptamer toward the highly expressed nucleolin on the MCF7 plasma membrane.
A sorbent with high selectivity and capacity for cadmium ions was prepared through immobilization of deep eutectic solvent (DES) of ChCl- glycerol containing the ligand ...2-(3-hydroxy-1-methylbut-2-enylideneamino)pyridine-3-ol (acacapyrH
2
) on the magnetic graphene oxide. A dispersive micro-solid phase extraction was designed, and the separated/preconcentrated cadmium ion was determined by flow injection flame atomic absorption spectrometry. After the optimization of effective parameters, the method showed linearity in the concentration range of 0.25–15 µg L
−1
with the coefficient of determination (
r
2
) of 0.9991 and enhancement factor of 195 for cadmium. The method was very sensitive with the detection limit (defined as 3S
b
/m) of 0.06 µg L
−1
. The method was successfully applied to the determination of Cd(II) in water (drinking and river), fruit (lemon, apricot, and peach) and meat (fish, chicken, and cow meat) samples.
