Sensitive determination of cadmium using solidified floating organic drop microextraction-slotted quartz tube-flame atomic absorption spectroscopy

Dual techniques for trace copper determination: DES/Dithizone based liquid phase microextraction-flame atomic absorption spectrophotometry and digital image based colorimetric probe

In this study, a sample preparation procedure was developed to preconcentrate copper ions from aqueous samples for determination by flame atomic absorption spectrometry (FAAS) and digital image based colorimetry (DIC) systems. This was achieved by complexing copper ions with dithizone (Cu-DZ) and extracting the complex from aqueous solution in a single step. For the DES/DZ-FAAS system, a low detection limit of 2.3 ng mL-1 was recorded over a broad and linear working range. For the DIC system, the linear relationship between the change in red color intensity of the red-green-blue (RGB) color scale and the concentration of copper in the Cu-DZ complex was utilized for the validation of the method. The DIC system also recorded a broad and linear working range with a satisfactory detection limit of 14.7 ng mL-1. Spike recovery experiments performed with eucalyptus tea extracts yielded high recovery results in the range of 91-107%.

Spectrophotometric determination of trace vanadium in fresh fruit juice samples by ion pair-based surfactant-assisted microextraction procedure with solidification of floating organic drop

An ion pair-based surfactant-assisted dispersive liquid-liquid microextraction with solidification of floating organic drop (IP-SA-DLLME-SFOD) was developed for extraction of vanadium followed by spectrophotometric determination. Tannic acid (TA) and cetyl trimethylammonium bromide (CTAB) were utilized as complexing and ion-pairing agents, respectively. Using ion-pairing, TA-vanadium complex became more hydrophobic and quantitatively extracted into 1-undecanol. Some factors that influence extraction efficiency were studied. Under optimized circumstances, the detection and quantification limits were 1.8 μg L-1 and 5.9 μg L-1, respectively. The method was linear up to 1000 μg L-1 and the enrichment factors was 19.8. For 100 μg L-1 vanadium, the intra-day, and inter-days relative standard deviations (n = 8) were 1.4% and 1.8%, respectively. The suggested IP-SA-DLLME-SFOD procedure has been effectively implemented for spectrophotometric quantification of vanadium in fresh fruit juice samples. Finally, the greenness of the approach was estimated using Analytical Greenness Calculator (AGREE), which proved its environmental friendliness and safety.

Accurate and sensitive determination of Sb(III) in water samples using UV-VIS spectrophotometry after simultaneous complexation and preconcentration with deep eutectic solvent/DTZ probe-based liquid-liquid microextraction

This study describes the determination of trace levels of antimony(III) by UV-Vis spectrophotometer after preconcentration by the deep eutectic solvent/dithizone probe-based liquid-liquid microextraction method. Ditizone was used as a ligand to form the coordinated antimony complex before extraction in the preconcentration process. In the microextraction method developed in the study, deep eutectic solvent was used to dissolve the complexing agent; thus, the complexation was performed at the same time as the extraction of antimony complex by deep eutectic solvent. All variables likely to affect the ligand-antimony(III) complex, extraction efficiency, and spectroscopic measurement were optimized to lower the detection limit. Under the determined optimum conditions, the detection limit for Sb was calculated as 1.6 × 10^-3 mg/L. The detection limit obtained with the method is much lower than the value obtained in the Uv-Vis spectrophotometer with the traditional method. In this study, the percent relative standard deviation for the lowest concentration was calculated as 3.12% (n = 8). This value indicates that the analysis performed has high precision. The applicability of the method was determined by performing spiked recovery tests on tap water taken from different regions. Satisfactory recovery results were obtained between 91 and 105% at three different concentrations.

A New Trend and Future Perspectives of the Miniaturization of Conventional Extraction Methods for Elemental Analysis in Different Real Samples: A Review

Sample preparation is one of the viable procedures to be used before analysis to enhance sensitivity and reduce the matrix effect. The current review is mainly emphasized the latest outcome and applications of microextraction techniques based on the miniaturization of the classical conventional methods based on liquid-phase and solid-phase extraction for the quantitative elemental analysis in different real samples. The limitation of the conventional sample preparation methods (liquid and solid phase extraction) has been overcome by developing a new way of reducing size as compared with the conventional system through the miniaturization approach. Miniaturization of the sample preparation techniques has received extensive attention due to its extraction at microlevels, speedy, economical, eco-friendly, and high extraction capability. The growing demand for speedy, economically feasible, and environmentally sound analytical approaches is the main intention to upgrade the conventional procedures apply for sample preparation in environmental investigation. A growing trend of research has been perceived to quantify the trace for elemental analysis in different natures of real samples. This review also recapitulates the current futuristic scenarios for the green and economically viable procedure with special overemphasis and concentrates on eco-friendly miniaturized sample-preparation techniques such as liquid-phase microextraction (LPME) and solid-phase microextraction (SPME). This review also emphasizes the latest progress and applications of the LPME and SPME approach and their future perspective.

Current development of bioanalytical sample preparation techniques in pharmaceuticals

Sample preparation is considered as the bottleneck step in bioanalysis because each biological matrix has its own unique challenges and complexity. Competent sample preparation to extract the desired analytes and remove redundant components is a crucial step in each bioanalytical approach. The matrix effect is a key hurdle in bioanalytical sample preparation, which has gained extensive consideration. Novel sample preparation techniques have advantages over classical techniques in terms of accuracy, automation, ease of sample preparation, storage, and shipment and have become increasingly popular over the past decade. Our objective is to provide a broad outline of current developments in various bioanalytical sample preparation techniques in chromatographic and spectroscopic examinations. In addition, how these techniques have gained considerable attention over the past decade in bioanalytical research is mentioned with preferred examples. Modern trends in bioanalytical sample preparation techniques, including sorbent-based microextraction techniques, are primarily emphasized.

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Bioanalytical sampling techniques are described with suitable applications in pharmaceuticals.

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The pros and cons of each bioanalytical sampling techniques are described.

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Relevant biological matrices are outlined.

Ultrasound-Assisted Ionic Liquid Microextraction for Preconcentration of Cadmium in Water, Vegetables and Hair Samples Prior to FAAS Determination

Background::

Cadmium (Cd2+) is considered to be one of the most important hazardous heavy metals due to its toxicity for living organisms at low concentration levels. Therefore, the estimation of trace Cd2+ in different types of various samples is a very important objective for chemists using effective methods. In the present work, a novel, green, easy and fast ultrasoundassisted ionic liquid-dispersive liquid phase microextraction technique (UA-IL-DLPME) was developed to preconcentrate and determine trace quantities of cadmium (Cd2+) ions from real samples, prior to detection by FAAS.

Methods:

The proposed technique is based on utilization of ionic liquid (IL) (1-hexyl-3- methylimidazolium tris(pentafluoroethyl)trifluorophosphate [HMIM][FAP]) as an extraction solvent for Cd2+ ions after complexation with 2-(6-methylbenzothiazolylazo)-6-nitrophenol (MBTANP) at pH 7.0. The impact of different analytical parameters on the microextraction efficiency was investigated. The validation of the proposed procedure was verified by the test of two certified reference materials (TMDA-51.3 fortified water, SRM spinach leaves 1570A) applying the standard addition method.

Results:

In the range of 2.0-200 μg L−1, the calibration graph was linear. Limit of detection, preconcentration factor and the relative standard deviation (RSD %, 100 μg L-1, n=5) as precision was 0.1 μg L-1, 100 and 3.1%, respectively.

Conclusion:

Green UA-IL-DLPME method was developed and applied to preconcentrate and determine trace quantities of Cd2+ in real water, vegetables and hair samples with satisfactory results.

Sensitive determination of nickel at trace levels in surface water samples by slotted quartz tube flame atomic absorption spectrometry after switchable solvent liquid-phase microextraction

In this study, switchable solvent (SS) for liquid-phase microextraction (LPME) was used as a tool to preconcentrate nickel from aqueous samples for determination by flame atomic absorption spectrometry. The SS-LPME method was optimized thoroughly to boost the absorbance signal of nickel for trace level determination. Parameters optimized included switchable solvent volume, sodium hydroxide concentration, sodium hydroxide volume, and eluent volume. The SS-LPME method enhanced the detection power by about 32-folds, and a slotted quartz tube (SQT) was used to obtain 2.6-folds increase in detection power. The combination of LPME and SQT-FAAS produced 104-folds enhancement, correlating to a limit of detection value of 1.8 μg/L. Low relative standard deviations calculated for the lowest calibration concentration indicated good repeatability for replicate measurements. Accuracy of the optimized method and its applicability to real samples was tested on two river samples. The results (85-103%) obtained from the spike recovery experiments were satisfactory.

A sieve-conducted two-syringe-based pressurized liquid-phase microextraction for the determination of indium by slotted quartz tube-flame atomic absorption spectrometry

In this study, a new liquid-phase microextraction method termed sieve-conducted two-syringe-based pressurized liquid-phase microextraction (SCTS-PLPME) was developed as a preconcentration tool for indium. Here, two syringes were connected to each other by an apparatus to produce an environment subject to pressure. The pressure created between the two syringes by simultaneous movements of the syringe plungers (to and fro) generated an efficient dispersion and this eliminated the need for dispersive solvents. Determination of indium after preconcentration was carried out with a slotted quartz tube attached flame atomic absorption spectrometer (SQT-FAAS). The detection limit (LOD) and quantification limit (LOQ) of the developed method were calculated as 19.2 and 72.2 μg L^-1, respectively. The reliability and accuracy of the developed method was tested by performing recovery studies on lake water spiked at different concentrations and the obtained percent recoveries were between 101.2 and 106.9%.

Trace determination of cobalt in biological fluids based on preconcentration with a new competitive ligand using dispersive liquid-liquid microextraction combined with slotted quartz tube-flame atomic absorption spectrophotometry

A new competitive ligand has been synthesized for the preconcentration to obtain lower detection limits by using dispersive liquid-liquid microextraction combined with slotted quartz tube-flame atomic absorption spectrophotometry (DLLME-SQT-FAAS). The proposed method is simple, eco-friendly and has high sensitivity. The preconcentration procedure was optimized on the basis of various parameters affecting the complex formation and extraction efficiency such as pH and volume of buffer solution, volume of ligand solution, mixing period, volume and type of extraction solvent, volume and type of dispersive solvent, and salt effect. Instrumental parameters were also optimized to get higher sensitivity. Under the optimum conditions, the calibration graph was linear in the range of 10-250 ng mL^-1and the resulted limits of detection and quantification (LOD and LOQ) for combined method were 4.7 and 15.7 ng mL^-1, respectively. The detection power was improved 48-fold using DLLME-SQT-FAAS method compared to conventional FAAS. The precision of the method was found to be high with a relative standard deviation of 2.5%. The accuracy of method was evaluated by recovery experiments using matrix matching study on spiked urine and blood samples. The recoveries for urine and blood samples ranged from 99.8 to 108.9% and 102.5 to 110.0%, respectively.

Development of an efficient and sensitive analytical method for the determination of copper at trace levels by slotted quartz tube atomic absorption spectrometry after vortex-assisted dispersive liquid-liquid microextraction in biota and water samples using a novel ligand

This study describes the determination of trace levels of copper by slotted quartz tube atomic absorption spectrometry after dispersive liquid-liquid microextraction. A ligand synthesized from the reaction of salicylaldehyde and 1-naphthylamine was used to form coordinate copper complex prior to extraction. All parameters that influence the output of complex formation, extraction, and instrumental measurement were optimized to enhance the absorbance signal of copper. Under the optimum conditions, about 104-fold enhancement in sensitivity was recorded over the conventional flame atomic absorption spectrometer, corresponding to a 0.51 ng/mL detection limit. The percent relative standard deviation calculated for the lowest concentration (4.8%) indicated high precision for the experimental procedure. Accuracy and applicability of the optimum method were determined by performing spiked recovery tests on urine, lake water, and mineral water samples. Satisfactory recovery results were obtained between 82.2 and 106.3% at four different concentrations. Matrix matching method was also performed to increase the accuracy of quantification, and the percent recovery calculated for 175 ng/mL was 105.14%.

Vortex-assisted switchable liquid-liquid microextraction for the preconcentration of cadmium in environmental samples prior to its determination with flame atomic absorption spectrometry

In this study, a switchable solvent was used to preconcentrate trace amounts of Cd from aqueous solution for its determination by flame atomic absorption spectrometry (FAAS). Protonation of N,N-dimethylbenzylamine by dry ice (solid CO₂) made it water soluble, and addition of sodium hydroxide converted it back to its original nonionic state for phase separation and subsequent extraction of Cd. A slotted quartz tube (SQT) was attached to the flame burner head to increase the residence time of Cd atoms in the light path. Under the optimum conditions, limits of detection and quantification were determined as 0.7 and 2.6 μg L^-1, respectively. Low relative standard deviations calculated from seven replicate measurements of the lowest concentration indicated high precision. Accuracy of the developed method was checked by using a standard reference material (SRM 1633c). Spiked recovery tests were also performed on lake water and wastewater samples at different concentrations to check the applicability of the developed method, and the results obtained (90-103%) established high recovery.