Picomolar level sensorial dual colorimetric gold nanoparticle sensor for Zn2+ and Hg2+ ions synthesized from bark extract of Lannea Grandis Coromandelica and its wide range applications in real sample analysis

In this work a facile, rapid, reproducible and non-toxic approach has been demonstrated for synthesis of most stable AuNPs from bark extract of Lannea Grandis Coromandelica. UV-Visible spectroscopy, FTIR, TEM, SAED, EDX, XRD, DLS, Zeta Potential, FE-SEM, AFM and XPS techniques were employed for the characterization of synthesized LGC-AuNPs. The UV-Vis spectra of LGC-AuNPs gave SPR peak at 536 nm while the TEM analysis revealed LGC-AuNPs have 20.75 nm size with spherical in shape. DLS study showed the AuNPs have average diameter 50.18 nm. The synthesized AuNPs exhibited very high selectivity, rapid response in recognition towards Zn2+ and Hg2+ ions by changing its color within 20 sec. This proposed sensor can detect very low picomolar level of Zn2+ and Hg2+ ions (LOD value for Zn2+ and Hg2+ were found 1.36 pM and 24.60 pM respectively). Here we also studied effect of several factors such as variation of conc of gold, temperature, incubation time, pH, salt, solvent (polar protic and polar aprotic) to know in which condition AuNPs have high stability and sensitivity. The data revealed that synthesized AuNPs was stable up to two years at pH 6.5 at room temperature in water media and under this condition, it shows maximum sensitivity and reactivity. Moreover, here interference study was carried out to identify high selectivity of synthesized LGC-AuNPs probe in presence of different metal ions. The real sample analyses also revealed the great applicability of this probe. Therefore, this simple, rapid, low-cost, sensing activity appeared to hold great sensibleness for detection of heavy metal ions in real sample.

In-situ formation of the adsorbent based on octadecylamine for the extraction of Ag+ ions from aqueous solutions and its determination by microinjection flame atomic absorption spectrometry

In this research, a dispersive solid phase extraction procedure based on changing the solubility of octadecylamine with pH was proposed to determine Ag+ ions in different water samples. For this purpose, first, the pH of sample solution containing the analyte was adjusted to 10.5. Then desired volume of the octadecylamine dissolved in acidic solution was injected into the solution. Because of the low solubility of octadecylamine in alkaline solution, a cloudy state was formed. The produced octadecylamine particles acted as a complexing agent for Ag+ ions and adsorbent for the formed complex. The obtained cloudy solution was centrifuged and the sedimented particles were removed and dissolved in a diluted nitric acid solution. It was injected into a flame atomic absorption spectrometry to determine the extracted amounts of the analyte. The effect of important parameters such as the amount of octadecylamine, volume of nitric acid, and centrifugation and vortexing conditions on the extraction efficiency of the procedure was studied and optimized. In optimal conditions, the developed method showed a linear range of 0.50-200 µg L-1. The limits of detection and quantification were 0.18 and 0.50 µg L-1, respectively. Extraction recovery was 93.6%. The relative standard deviations were less than 4%. The effectiveness of the method was investigated by determination of Ag+ ions in water and wastewater samples.

Determination of copper(II) and lead(II) ions in dairy products by an efficient and green method of heat-induced homogeneous liquid-liquid microextraction based on a deep eutectic solvent

In this study, a new homogeneous liquid-liquid microextraction method using a deep eutectic solvent has been developed for the extraction of Cu(II) and Pb(II) ions in dairy products. Initially, the deep eutectic solvent was synthesized using choline chloride and p-chlorophenol and used as the extraction solvent. The synthesized solvent was soluble in milk at 70 °C and its separation from the sample was performed by decreasing the temperature. By cooling, a cloudy solution was formed due to the low solubility of the solvent at low temperatures. On centrifugation, the fine droplets of the solvent containing the analytes settled at the bottom of the tube by sedimentation. The enriched analytes were determined by flame atomic absorption spectrometry. The effect of some important parameters such as the amount of protein precipitating agent , complexing agent amount, extraction solvent volume, salt addition, pH, and temperature on the extraction efficiency of the method was studied and optimized. Under the optimal conditions, the linear ranges of the method for Cu(II) and Pb(II) ions were obtained in the ranges of 0.10-50 and 0.50-50 μg L-1 with detection limits of 0.04 and 0.18 μg L-1, respectively. The repeatability of the developed method, expressed as relative standard deviation, was determined to be 3.2 and 3.9% for Cu(II) and Pb(II) ions, respectively. Finally, by determining the concentration of Cu(II) and Pb(II) ions in milk, doogh, and cheese samples, the feasibility of the method was successfully confirmed with the extraction recoveries of 95.9 and 92.1% for Cu(II) and Pb(II) ions, respectively.

Salt-Induced Homogeneous Liquid–Liquid Microextraction of Piroxicam and Meloxicam from Human Urine Prior to Their Determination by HPLC-DAD

A salt-induced homogeneous liquid–liquid microextraction (SI-HLLME) protocol combined with high-performance liquid chromatography–diode array detection is presented for the first time for the determination of piroxicam and meloxicam in human urine. The main parameters affecting the performance of the sample preparation protocol were optimized by means of a two-step experimental design (i.e., 2-level fractional factorial design and Box–Behnken design). Following its optimization, the proposed method was thoroughly validated in terms of the total error concept in order to take into consideration the random and systematic errors. For the target analytes, accuracy profiles were constructed, and they were used as graphical decision-making tools. In all cases, the β-expectation tolerance intervals complied with the acceptance criteria of ±15%, proving that 95% of future results will fall within the defined bias limits. The limits of detection were 0.02 μg mL−1 and 0.03 μg mL−1 for piroxicam and meloxicam, respectively. The relative standard deviations were lower than 4.4% in all cases, and the mean relative biases ranged between −5.7 and 3.4% for both drugs. The proposed scheme is simple and rapid, while it is characterized by high sample throughput. Moreover, SI-HLLME requires reduced sample and reagent consumption, according to the requirements of Green Analytical Chemistry.

Pyrene-Based AIEE Active Nanoprobe for Zn2+ and Tyrosine Detection Demonstrated by DFT, Bioimaging, and Organic Thin-Film Transistor

The development of aggregation-induced emission enhancement (AIEE) active nanoprobes without any synthetic complication for solution-state and organic thin-film transistor (OTFT)-based sensory applications is still a challenging task. In this study, the novel pyrene-incorporated Schiff base (5-phenyl-4-((pyren-1-ylmethylene)amino)-4H-1,2,4-triazole-3-thiol; PT2) with an AIEE property was synthesized via a one-pot reaction and was reported for detecting Zn²⁺ and tyrosine in the solution state and OTFT. In the AIEE studies of PT2 (in CH₃CN) at various water fractions (f_w: 0-97.5%), the existence of J-aggregation, crystalline changes, and nanofibers formation was confirmed by ultraviolet absorption/photoluminescence (UV/PL) spectroscopy, powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), and dynamic-light scattering (DLS) techniques. Similarly, PT2-based Zn²⁺ detection and sensory reversibility with tyrosine were demonstrated by UV/PL studies with evidence related to crystalline/nanolevel changes in PXRD, SEM, TEM, AFM, and DLS data. Distinct decay profiles associated with the AIEE and sensory responses of PT2 were observed in time-resolved photoluminescence spectra. From the standard deviation and linear fittings of PL titrations, detection limits (LODs) of the Zn²⁺ with PT2 and the tyrosine with PT2-Zn²⁺ were estimated as 0.79 and 45 nM, respectively. High-resolution mass and ¹H NMR results confirmed 2:1 and 1:1 stoichiometry and binding sites of PT2-Zn²⁺-PT2* and tyrosine-Zn²⁺ complexes. Moreover, the values of association constants determined by linear fittings were 4.205 × 10^-7 and 1.73 × 10^-8 M^-2, correspondingly. Optimization via the density functional theory disclosed the binding sites and suppression of twisted intramolecular charge transfer/photoinduced electron transfer (TICT/PET) as well as the involvement of restricted intramolecular rotation in the AIEE and PET "ON-OFF-ON" mechanisms in the Zn²⁺ and tyrosine sensors. Results from the B16-F10 cellular and zebrafish imaging of AIEE, Zn²⁺, and tyrosine sensors further attested the applicability of PT2 in biological samples. Finally, the PT2 and pentacene-incorporated OTFT devices were fabricated. The devices displayed more than 90% change in drain-source current when reacted with Zn²⁺ with an LOD of 5.46 μM but showed no response to tyrosine, thereby confirming the reversibility. Moreover, the OTFT devices also demonstrated Zn²⁺ ion detection in tap water and lake water samples.

Determination of 8 biogenic amines in aquatic products and their derived products by high-performance liquid chromatography-tandem mass spectrometry without derivatization

A method for the determination of 8 biogenic amines in aquatic products and their derived products was established by HPLC-MS/MS without derivatization. The samples were extracted by 5% perchloric acid solution. N-hexane was used to clean the extract. The analytes were separated by a column of ACQUITY UPLC HSS T3 (100 mm × 2.1 mm, 1.8 µm), and gradient eluted with a mixed solution of (0.5% formic acid) and acetonitrile. Good linearity was obtained with correlation coefficients (R²) >0.99. This method achieved higher sensitivity (from 0.1 mg/kg for tyramine, 2-phenylethylamine and tryptamine to 1.0 mg/kg for spermidine, spermine, cadaverin, histamine and putrescine). The average recoveries were demonstrated in the range of 70.9%-113.1%, with relative standard deviations (RSDs) from 0.33% to 10.81%. This method was suitable for the detection of BAs in aquatic products and their products.

Derivatization and deep eutectic solvent-based air-assisted liquid-liquid microextraction of salbutamol in exhaled breath condensate samples followed by gas chromatography-mass spectrometry

A microwave-induced air-assisted liquid-liquid microextraction method has been proposed for the pretreatment/quantization of salbutamol in exhaled breath condensate (EBC) samples prior to gas chromatography-mass spectrometry. In this procedure, 1-fluoro-2,4-dinitrobenzene and N,N-diethylethanolammonium chloride: dichloroacetic acid: octanoic acid deep eutectic solvent were exploited as derivatization reagent and extraction solvent, respectively. A mixture of the sample solution and pyridine was transferred into a test tube. Then, a mixture of extraction solvent and derivatization agent was placed at the bottom of the tube. After performing the predetermined extraction cycles in the microextraction method, the mixture was exposed to microwave irradiations to enhance derivatization and extraction efficiencies. The obtained turbid solution was centrifuged and a portion of the sedimented phase was used for quantification of salbutamol. The validated method showed low limits of detection (0.074 and 0.370 μg/L in deionized water and EBC, respectively), quantification (0.246 in deionized water and 1.23 μg/L in EBC), and lower limit of quantification (0.123 and 0.615 μg/L in deionized water and EBC, respectively). The method had appropriate repeatability, accuracy, and stability (expressed as relative standard deviation less than 9%). The developed method was used in quantification of salbutamol in the real samples collected from donors receiving salbutamol spray.

Development of homogeneous liquid-liquid extraction combined with dispersive liquid-liquid microextraction based on solidification of floating droplets of a ternary component deep eutectic solvent for the analysis of antibiotic residues in sausage samples prior to ion mobility spectrometry

In this study, a combination of homogeneous liquid-liquid extraction and dispersive liquid-liquid microextraction based on solidification of a deep eutectic solvent has been utilized as an efficient method for the extraction of three widely used antibiotics (oxytetracycline, penicillin G, and tilmicosin) from sausage samples. In this method, initially the antibiotics are extracted from the powdered sausage sample into acetonitrile and then, to concentrate the analytes and achieve a high sensitivity, the obtained acetonitrile is mixed with an extraction solvent (a newly synthesized water-immiscible deep eutectic solvent with a melting point near room temperature), and the obtained mixture is rapidly injected into deionized water. In the next step, the mixture is transferred into an ice bath and the solidified extraction solvent containing the analytes is removed and dissolved in ACN. For quantitative analysis, this phase is taken and injected into an ion mobility spectrometer which operated in the positive mode and is equipped with a continuous corona discharge ionizer. This instrumental technique characterizes molecules based on the gaseous phase mobility of their ions formed at ambient pressure and under an electric field. Under the optimum conditions, limits of detection and quantification were achieved in the ranges of 1.52-2.73 and 5.1-9.1 ng g^-1, respectively. The relative standard deviations were less than 8% for intra- (n = 6) and inter-day (n = 4) precisions at a concentration of 20 ng g^-1 of each analyte. Finally, the proposed method was applied to the analysis of the studied antibiotics in fifteen different sausage samples marketed in Tabriz, Iran. Oxytetracycline was determined in three of the studied sausage samples.

Dispersive solid phase extraction combined with solidification of floating organic drop-liquid-liquid microextraction using in situ formation of deep eutectic solvent for extraction of phytosterols from edible oil samples

In this study, a dispersive solid phase extraction method was combined with solidification of floating organic drop-liquid-liquid microextraction based on in situ synthesis of deep eutectic solvent. It was used for the extraction of some phytosterols from edible oil samples. The extracted analytes were quantified by gas chromatography-mass spectrometry. In this procedure, the sample lipids are saponified with sodium hydroxide and then the analytes are adsorbed onto an octadecylsilane sorbent. After that the analytes are desorbed from the sorbent with ethanol as an elution solvent and the eluant is diluted with deionized water to obtain a homogenous solution. Then, a few amounts of choline chloride and n-butyric acid are dissolved in the solution and transferred into a water batch adjusted at 75 ⁰C for 5 min. During this period Choline chloride and n-butyric acid form a deep eutectic solvent (extraction solvent) dispersed in whole parts of the solution. The obtained cloudy solution is placed into an ice bath. The extraction solvent is collected and solidified on the top of the solution. Finally, it is removed and allows melted at room temperature and an aliquat of the solution is injected into the separation system. Validation of the method showed that limits of detection and quantification were in the ranges of 0.52-1.6 and 1.7-5.6 ng mL-1, respectively. Enrichment factors and extraction recoveries of the analytes ranged from 312 to 375 and 75-90%, respectively. The method had a proper percision with relative standard deviations less than ≤8.2% for intra- (n = 6) and inter-day (n = 6) precisions at a concentration of 15 ng mL-1 of each analyte. Finally the method was successfully used for determination of the analytes in some edible oil samples.

Cyclohexylamine as extraction solvent and chelating agent in extraction and preconcentration of some heavy metals in aqueous samples based on heat-induced homogeneous liquid-liquid extraction

A new sample preparation method has been developed for extraction and preconcentration of some heavy metal cations in aqueous samples using cyclohexylamine-based homogeneous liquid-liquid microextraction. In the proposed method, cyclohexylamine was used as both the complexing agent and the extraction solvent. For this purpose, cyclohexylamine at µL level was initially added into an aqueous solution containing Co(II), Ni(II), and Cu(II) ions which was placed in a glass test tube. The mixture was shaken for forming a homogeneous solution. Then sodium chloride was added to the solution. After shaking manually again, the test tube was placed in a water bath thermostated at 70°C. Due to lower solubility of cyclohexylamine at the elevated temperature, a cloudy solution was formed. The fine droplets of cyclohexylamine containing cation-cyclohexylamine complexes were collected on the top of the aqueous phase by centrifuging. The enriched analytes in the upper phase were determined by graphite furnace atomic absorption spectrometry. Several variables possibly affecting the extraction efficiency were investigated and optimized. Under the optimum conditions the calibration curves were linear in the ranges of 80-1000, 40-700, and 80-800ngL^-1 for Co²⁺, Ni²⁺, and Cu²⁺, respectively. Repeatability of the proposed method, expressed as relative standard deviation, ranged from 3.3% to 5.2% (n = 6, C = 200ngL^-1). Moreover, the obtained detection limits of the selected analytes were in the range of 15.3-37.7ngL^-1. The accuracy of the developed procedure was verified by analyzing a certified reference material, namely NRCC-SLRS4 Riverine water. Finally, the proposed method was successfully applied for the simultaneous analysis of the selected analytes in environmental water samples.