Array Detection Spectrophotometry Research Articles

Rotative Liquid-Liquid Microextraction as a Preconcentration Method in Combination with Fiber Optic-Linear Array Detection Spectrophotometry for the Determination of Cobalt in Pharmaceutical Samples

A new and fast solvent microextraction method, termed rotative liquid-liquid microextraction (RLLME), has been introduced and used for real sample analysis. RLLME in combination with fiber optic-linear array detection spectrophotometry was used for pharmaceutical sample analysis. The proposed method was compared with other methods and its applicability was evaluated by the determination of cobalt in pharmaceutical samples including B12 ampoule, B-complex ampoule, and Neobion ampoule, as well as Centrum capsule as a nutritive supplement. Accuracy of the method was proved using certified reference material.Under the optimum conditions, the preconcentration time was 30 s, which is one of the shortest preconcentration times reported to date. The calculated calibration curves gave high levels of correlation coefficients (r2) greater than 0.9993, the limit of detection (LOD) of the method was 0.12 ng mL−1, and the relative standard deviation (R.S.D.) was 1.9 % for 50 ng mL−1 cobalt.

Graphene oxide magnetic nanocomposites for the preconcentration of trace amounts of malachite green from fish and water samples prior to determination by fiber optic-linear array detection spectrophotometry

In this work, a graphene oxide magnetic nanocomposite (GO/Fe3O4) was prepared and used as an effective adsorbent for the magnetic solid-phase extraction of trace quantities of malachite green from fish and water samples. This method, which takes advantage of both graphene oxide adsorption and magnetic phase separation from the sample solution, avoids some of the time-consuming experimental procedures related to the traditional solid phase extraction. The excellent adsorption property of the GO/Fe3O4 system is due to the π–π stacking interaction and also electrostatic interactions between oxygen-containing functional groups on the graphene oxide and the cationic dye. The effects of the amount of the extractant composite employed, extraction time, pH values, interfering ions and desorption conditions were investigated. Under optimum conditions, the calibration graph was linear over the range of 1.3–300.0 μg L−1, and an enrichment factor (EF) of 150 was obtained. The detection limit was 0.39 μg L−1, and a relative standard deviation of 2.46% at 60 μg L−1 was obtained (n = 5). The maximum adsorption capacity of the adsorbent under optimum conditions was found to be 27.9 mg g−1 for malachite green. The developed method was successfully applied for the determination of malachite green in fish and water samples.

Application of modified nano-γ-alumina as an efficient adsorbent for removing malachite green (MG) from aqueous solution

This study describes a simple, inexpensive and sensitive extraction procedure using γ-Al2O3 nanoparticles modified with sodiumdodecylsulfate, as an efficient solid phase, for removal, preconcentration and spectrophotometric determination of trace amounts of malachite green (MG) by fiber optic-linear array detection spectrophotometry. The properties of the produced modified nanoparticles were determined by FESEM and TEM. Various effective parameters on the preconcentration of MG, such as pH, sample volume, amount of sorbent, type, concentration, contact time, temperature, and volume of eluent were investigated. Under the optimized operating conditions, the calibration graph was linear over the range of 1.2–250 μg L−1 and relative standard deviation of 1.50% at 100 μg L−1 were obtained (n = 5). The limit of detection (S/N = 3) was obtained 0.34 μg L−1. The Langmuir adsorption capacity (qmax) was found to be 72.4 mg g−1 of the adsorbent. The method has been successfully used to determine of MG in fish farming water with satisfactory results.

High-density solvent-based de-emulsification microextraction technique combined with fiber optic-linear array detection spectrometry for fast determination of ppb-level phenol index

In this work, a simple, rapid, and efficient solvent-based de-emulsification microextraction technique using high-density solvent has been developed for determining phenol index in water samples for the first time. The extraction of phenolic compounds in the aqueous sample solution was performed by using chloroform (as extraction solvent) and acetone (as dispersive solvent) in the presence of 4-aminoantipyrine (4-AAP) as chromogenic reagent. A de-emulsification solvent (ACN) was then injected into the sample solution to break up the emulsion, and then obtained emulsion cleared into two phases quickly, with no centrifugation step. The lower layer organic phase transferred into a microcell of a fiber optic-linear array detection spectrophotometry. The effect of various parameters on the extraction recovery was investigated. Under the optimized conditions and preconcentration of 10 mL of sample, the enhancement factor of 140 and the detection limit of 0.6 μg L−1 were obtained. Validation of the method was performed by spiking recovery method and comparison of results with those obtained by American Society for Testing and Materials standard method.

Indirect spectrophotometric determination of ultra trace amounts of selenium based on dispersive liquid–liquid microextraction–solidified floating organic drop

A novel dispersive liquid–liquid microextraction–solidified floating organic drop (DLLME–SFOD) method combined with fiber optic-linear array detection spectrophotometry has been developed for the indirect determination of selenium. The method is based on the oxidation of the I− to iodine by inorganic Se(IV). The produced I2 reacts with the excess of I− ions in acidic media to give triiodide ions. The I3- is then extracted into 1-undecanol by DLLME–SFOD upon the formation of an ion pair with cetyltrimethylammonium cation. The extracted ion pair is determined by measuring its absorption at 360nm. The absorbance signal is proportional to the selenium concentration in the aqueous phase. Under optimum conditions, the method provided an enrichment factor of 250 with a detection limit of 16.0μgL−1 and a linear dynamic range of 40.0–1000.0μgL−1. The relative standard deviation was found to be 2.1% (n=7) at 100.0μgL−1 concentration level. The method was successfully applied to the determination of selenium in water samples and selenium plus tablet.

Selective and sensitive speciation analysis of Cr(VI) and Cr(III) in water samples by fiber optic-linear array detection spectrophotometry after ion pair based-surfactant assisted dispersive liquid–liquid microextraction

A simple ion pair based-surfactant assisted dispersive liquid–liquid microextraction (IP-SA-DLLME) was evaluated for extraction and preconcentration of Cr(VI) and Cr(III) in aqueous samples. In this method, which was used for the first time for chromium speciation analysis, sodium dodecyl sulfate (SDS) was used as both ion-pairing and disperser agent. Cr(VI) ions were converted into their cationic complex with 1,5-diphenylcarbazide (DPC) and then extracted into 1-octanol dispersed in aqueous solution. Cr(III) ion also can be determined by this procedure after oxidation to Cr(VI). After extraction and phase separation, upper organic phase was transferred to a micro cell of a fiber optic-linear array detection spectrophotometry (FO-LADS). The effects of various parameters on the extraction recovery were investigated. Under the optimized conditions and preconcentration of 10mL of sample, the enrichment factor of 159 and the detection limit of 0.05μgL−1 were obtained. Validation of the method was performed by spiking-recovery method and comparison of results with those obtained by ET-AAS method.

Fast Analysis of Water Samples for Trace Amount of Crystal Violet Dye Based on Solid Phase Extraction Using Nanoporous SBA‐3 prior to Determination by Fiber Optic‐Linear Array Detection Spectrophotometry

A solid phase preconcentration procedure using SBA‐3 nanosorbent for the fast separation and preconcentration of crystal violet (CV) in water samples by fiber optic‐linear array detection spectrophotometry (FO‐LADS) is presented. Experimental parameters including pH, sample volume, amount of sorbent, type, volume, and concentration of eluent that affect the recovery of crystal violet have been optimized. Under optimized experimental conditions, analytical parameters including limit of detection, linear working range, and relative standard deviation have also been determined. A preconcentration factor of 200 was achieved in this method. In the initial solution, the detection limit for CV was found as 1.3 μg L−1. Under optimal conditions maximum adsorption capacity was obtained as 344.83 mg g−1. Also, the relative standard deviation was less than ±1.3% (n = 5). The presented procedure was applied to the determination of crystal violet in water samples (fish, fish farming water, and river water) with good results.

The ultratrace detection of crystal violet in fish and environmental water samples using cold-induced aggregation microextraction based on ionic liquid (IL-CIAME)

A new method based on ionic liquid cold-induced aggregation microextraction (IL-CIAME) in combination with fiber optic-linear array detection spectrophotometry (FO-LADS) has been developed for the analysis of crystal violet (CV) in saline samples. In this methodology, a suitable temperature is used to fully dissolve very small amounts of 1-hexyl-3-methylimidazolium hexafluorophosphate [Hmim][PF6] and 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [Hmim][Tf2N] as hydrophobic ionic liquids (ILs) and extractant solvents in the sample solution without the use of a disperser solvent. After dissolving, the solution was cooled in an ice bath and a cloudy solution of IL fine droplets was formed due to the decrease of IL solubility. After centrifuging, the fine droplets of the extractant phase settled to the bottom of the conical-bottom centrifuge tube. In this method, which is robust against high content of salt and water-miscible organic solvents, various parameters were investigated and optimized. Under the optimum conditions, the limit of detection (LOD) of the method was 1.16 μg L−1 and the relative standard deviation (RSD) for 20 μg L−1 CV was 2.30%. The obtained results indicated that the developed method is an excellent alternative for routine analysis in the environmental field.

Determination of Sulfite in Water and Dried Fruit Samples by Dispersive Liquid–Liquid Microextraction Combined with UV–Vis Fiber Optic Linear Array Spectrophotometry

A simple and rapid dispersive liquid–liquid microextraction (DLLME) method was applied to preconcentrate sulfite ions from aqueous samples as a prior step to its determination by fiber optic-linear array detection spectrophotometry. The procedure is based on the color reaction of sulfite with o-phthaldialdehyde (OPA) in the presence of ammonia to form isoindole and extraction of the formed isoindole derivative using the DLLME technique. The conditions for the microextraction performance were investigated and optimized. The calibration graph was linear in the range of 2–100 μg L−1with a detection limit of 0.2 μg L−1. The relative standard deviation for five replicate measurements of 10 and 50 μg L−1of sulfite were 2.8 and 2.0 %, respectively. Under the optimized conditions, the enrichment factor of ~133 was obtained from a sample volume of 10 mL. The proposed method was successfully applied to the sulfite determination in drinking water and in food samples.

Robust ionic liquid against high concentration of salt for preconcentration and determination of rhodamine B

Resistant ionic liquid-based dispersive liquid–liquid microextraction (IL-based DLLME) method is described for sensitive determination of trace amounts of rhodamine B in aqueous samples containing very high salt concentrations by fiber optic-linear array detection spectrophotometry (FO-LADS). The method is based on the DLLME of rhodamine B from aqueous solution using ionic liquid. The robustness of microextraction system against high salt concentration (up to 40%, w/v) is increased by introducing a common ion of the ionic liquid into the sample solution. The extracted rich phase is diluted with acetone, and its absorbance is measured at 556nm by a spectrophotometer. The effects of different operating parameters such as concentration of salt, pH, effect of IL and disperser solvent and NaPF6 on the DLLME of rhodamine B were studied in details. Under optimum conditions a linear calibration graph in the range of 5–100μgL−1 of rhodamine B in the initial solution with R2=0.9993 (n=10) was obtained. Detection limit based on three times the standard deviation of the blank (3Sb) was 1.05μgL−1 (n=10) and the relative standard deviation (R.S.D.) for 50μgL−1 of rhodamine B was 1.3% (n=10), respectively. The proposed method was successfully applied for the determination of rhodamine B in various samples.

Speciation and preconcentration of iron by cloud point extraction combined with fibre optic linear array detection spectrophotometry

A highly selective method for speciation and preconcentration of iron was developed using cloud point extraction (CPE) combined with fibre optic-linear array detection spectrophotometry (FO-LADS). Cloud point extraction method was based on the chromogenic reaction of Fe(II) and Fe(III) with 1-(2-pyridylazo)-2-naphthol (PAN) and then preconcentration of formed complexes using octylphenoxy polyethoxy ethanol (Triton X-114). When the system temperature is higher than the cloud point extraction temperature (CPT) of selected surfactant, the complex of Fe(II) with 1-(2-pyridylazo)-2-naphthol (PAN) could enter surfactant-rich phase, whereas the complex of Fe(III) remained in aqueous phase. Thus, an in situ separation of Fe(II) and Fe(III) could be realized. An iron complex in the surfactant-rich phase was determined by fibre optic-linear array detection spectrophotometry.The main factors affecting the cloud point extraction, such as pH, concentration of (PAN) and Triton X-114, equilibration temperature and time, were investigated systematically. Under the optimized conditions, the enhancement factors of 167 and 158 were obtained for Fe(II) and Fe(III) respectively, the limits of detection (LOD) was 0.2 μg L−1 for Fe(II) and 0.5 μg L−1 for Fe(III). The relative standard deviations (n = 5, c = 40.0μg L−1) was lower than 3%. The proposed method is highly selective without any interference ions. This method was successfully applied to the speciation of iron in different samples with satisfactory results.

Surfactant Enhance DLLME/FO‐LADS: Assay of Malachite Green Level in Aquatic Environment of Trout Fish

AbstractMalachite green (MG), a traditional agent used in aquaculture although is not approved; its low cost and high efficacy make illicit use likely. We developed a small‐scale, simple, and sensitive dispersive liquid–liquid microextraction procedure for the assay of trace amounts of MG in aquatic environment of Trout fish. Fiber optic‐linear array detection spectrophotometry with charge‐coupled device detector benefiting from a microcell was used for this purpose. The method is based on enhancement effect of an anionic surfactant on the extraction of MG in to very fine multidroplets of microextraction solvent which made assisted by disperser solvent. Under the optimum conditions, the enrichment factor 77.5 was obtained from a 5‐mL water sample. The calibration graph was linear up to 5 × 10−7 mol L−1 with detection limit of 1 × 10−8 mol L−1. The relative standard deviation for seven replicate measurements of 4 × 10−7 and 5 × 10−8 mol L−1 of MG were 3.3 and 4.5%, respectively.

A novel methodology based on solvents less dense than through dispersive liquid-liquid microextraction: application in quantitation of in fruit juices and soft drinks by fiber optic-linear array detection spectrophotometry.

In this study a novel methodology is proposed for utilizing solvents less dense than water by using a dispersive liquid-liquid microextraction (DLLME) technique. Conventional microextraction vessels and facile strategy have been used. We have avoided using routine microextraction solvents in the DLLME procedure that are mostly chlorinated, dense, environmentally hazardous and expensive which limits the application of this method to some extent. The aforesaid process has been combined with fiber optic-linear array detection spectrophotometry (FO-LADS) with charge-coupled device (CCD) detector benefiting of a micro-cell. l-Ascorbate was selected as a model compound and the proposed method was carried out for preconcentration and assay of iodine produced by reduction of potassium iodate in fruit juices, soft drinks and pharmaceutical preparations. The influences of the various analytical parameters on the microextraction procedure and oxidation reaction have been evaluated and optimized. The accuracy of the method was confirmed by parallel analyses as the reference method (ISO 6557/2). The calibration curve was linear in the range of 1.76-26.40 μg mL-1 of l-ascorbate with a correlation coefficient (r) of 0.9912. The LOD obtained from the calibration curve was 0.40 μg mL-1.

Ionic liquid-based dispersive liquid–liquid microextraction and enhanced spectrophotometric determination of molybdenum (VI) in water and plant leaves samples by FO-LADS

A new simple and rapid ionic liquid-based dispersive liquid–liquid microextraction (IL-DLLME) has been applied to preconcentrate trace levels of molybdenum (VI) as a prior step to its enhanced determination by fiber optic-linear array detection spectrophotometry (FO-LADS). In this method, a small amount of [Hmim][Tf2N] (1-hexyl-3-methylimmidazolium bis (trifluormethylsulfonyl) imid) as an extraction solvent was applied to extract molybdenum – pyrogallol red complex, which was formed in an aqueous solution in the presence of N-cetyl-N-N-N-trimethyl ammonium chloride as a sensitizing agent. Under optimum conditions, enhancement factor, detection limit and relative standard deviation (n=5, for 30μgL−1 of molybdenum (VI)) in 10mL water sample were 72.6, 1.43μgL−1 and 2.8%, respectively.

Development and evaluation of a dispersive liquid-liquid microextraction based test method for quantitation of total anionic surfactants: advantages against reference methods

Abstract A small-scale, simple, and rapid dispersive liquid-liquid microextraction (DLLME) procedure in combination with fiber optic-linear array detection spectrophotometry (FO-LADS) with charge-coupled device (CCD) detector has been developed, with benefits from the use of a micro-cell. The official reference methods (ASTM D2330 - 02, ISO 7875-1), which require tedious procedures, were replaced with a modified method. The new method provides a major reduction in sample size, elimination of the use of expensive glassware, and a decrease in the quantity of chloroform used, as well as increased sensitivity. Our method requires only one twentieth of the sample (5.0 mL), and less than one three-hundredth of microextraction solvent (chloroform = 138 µL). It provides a faster analysis time than official analytical methods (less than one minute). The calibration curve was linear in the range of 6–80 µg g L−1 of sodium dodecyl sulfate (SDS) with a correlation coefficient (r) of better than 0.99 and the LOD was 2 µg L−1. The repeatability of the proposed method (n=7) was found to be 4.5% and 3.6% for the concentrations of 0.03 and 0.07 mg L−1, respectively. The enrichment factor was found to be 75 for SDS.

Fiber optic-linear array detection spectrophotometry in combination with dispersive liquid-liquid microextraction for preconcentration and determination of copper

In this research, simple, rapid and efficient method, dispersive liquid-liquid microextraction (DLLME) combined fiber optic -linear array detection spectrophotometry (FO-LADS) was developed using a cylindrical micro-cell for preconcentration and determination of Cu(II) in samples. DLLME and FO-LADS methods have good matching conditions for being combined since FO-LADS is a suitable method for the determination of analytes in low volume of the remained phase obtained after DLLME. Molar absorptivity of complex Cu with (4-benzylp iperidineditiocarbamate potassium salt) (BPDC) was determined as 2.75 × 104 L mol-1 cm-1 at 7nmax = 436 nm. Under the optimum conditions the calibration graph was linear in the rage of 2–70 fug L-1 with detection limit of 0.34 fug L-1. The proposed procedure was successfully applied to the determination of Cu(II) in real water samples and human urine sample.

Cold-induced aggregation microextraction based on ionic liquids and fiber optic-linear array detection spectrophotometry of cobalt in water samples

A new simple and rapid cold-induced aggregation microextraction (CIAME) method was applied to preconcentrate cobalt(II) ions from water samples as a prior step to its determination by fiber optic-linear array detection spectrophotometry (FO-LADS). In this method, very small amounts of 1-hexyl-3-methylimidazolium hexafluorophosphate [Hmim][PF 6] and 1-hexyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide [Hmim][Tf 2N] as hydrophobic ionic liquids (ILs) and extractant solvents were dissolved in the sample solution containing Triton X-114 (anti-sticking agent). 1-(2-Pyridylazo)-2-naphthol (PAN) was chosen as the complexing agent. After dissolving, the solution was cooled in the ice bath and a cloudy solution was formed of IL fine droplets due to the decrease of IL solubility. After centrifuging, the fine droplets of extractant phase were settled to the bottom of the conical-bottom centrifuge tube. Analysis was carried out by a fiber optic-linear array detector spectrophotometer at 570 nm. In this method, which is robust against high content of salt and water-miscible organic solvents, various parameters were investigated and optimized. The applicability of the technique was evaluated by the determination of trace amounts of cobalt in several water samples. Under the optimum conditions, the limit of detection (LOD) of the method was 0.14 ng mL −1 and the relative standard deviation (R.S.D.) for 30 ng mL −1 cobalt was 2.32%.

Fiber optic-linear array detection spectrophotometry in combination with cloud point extraction for simultaneous preconcentration and determination of cobalt and nickel

A new combined method including fiber optic-linear array detection spectrophotometry (FO-LADS) and cloud point extraction (CPE) was developed using a cylindrical micro cell for simultaneous preconcentration and determination of different species. The CPE and FO-LADS methods have good matching conditions for combination because FO-LADS is suitable as a detection technique for the low volume of remained phase obtained after CPE. This combination was carried out using 50 μL cylindrical micro cell and then employed for simultaneous preconcentration and determination of cobalt and nickel. Cloud point extraction method was based on the chromogenic reaction of metal ions and 1-(2-pyridylazo)-2-naphthol (PAN) and then preconcentration of formed complexes using octylphenoxypolyethoxyethanol (Triton X-114). The remained phase after CPE was transferred into cylindrical micro cell and located at the cell holder of FO-LADS. The spectra of cobalt and nickel complexes were collected by FO-LADS and processed for ordinary and first derivative spectrophotometry. Optimization of different parameters was evaluated. Under optimum conditions, calibration curves were linear in the range of 0.6–30.0 and 0.1–15.0 μg L −1 with detection limits of 0.2 and 0.04 μg L −1 for Co and Ni respectively. The relative standard deviations (R.S.D.s) were lower than 4%. The obtained enhancement factors were 198 and 199 for cobalt and nickel, respectively. The proposed method was compared with the other methods and applied to the analysis of several real and spiked samples.

Fiber optic-linear array detection spectrophotometry in combination with dispersive liquid–liquid microextraction for simultaneous preconcentration and determination of palladium and cobalt

A new combined method including fiber optic-linear array detection spectrophotometry (FO-LADS) and dispersive liquid–liquid microextraction (DLLME) was developed using a cylindrical micro-cell for simultaneous preconcentration and determination of different species. DLLME and FO-LADS methods have good matching conditions for being combined since FO-LADS is a suitable method for the determination of analytes in low volume of the remained phase obtained after DLLME. DLLME technique was successfully used as a sample preparation method. In this preconcentration method, an appropriate mixture of ethanol (the disperser solvent) and 1,2-dichlorobenzene (the extraction solvent) was injected rapidly into the water sample containing palladium and cobalt after complex formation using 1-(2-pyridylazo)-2-naphthol (PAN) reagent. After phase separation, 50 μL of the sedimented phase containing enriched analytes was determined by FO-LADS. The ordinary and first derivative absorption spectra were obtained for optimization and simultaneous determination of palladium and cobalt, respectively. Under the optimum conditions, the calibration graphs were linear in the range of 2–100 μg L −1 and 1–70 μg L −1 with detection limit of 0.25 μg L −1 and 0.2 μg L −1 for palladium and cobalt, respectively. The relative standard deviations (R.S.D.s, n = 5) were lower than 4%. The enhancement factors of 162 and 165 were obtained for palladium and cobalt, respectively. The proposed method was compared with other methods and applied to the analysis of several real and synthetic samples with satisfactory results.

Simultaneous Determination of Iron, Copper and Cobalt in Food Samples by CCD-diode Array Detection-Flow Injection Analysis with Partial Least Squares Calibration Model

A flow injection-CCD diode array detection spectrophotometry with partial least squares (PLS) program for simultaneous determination of iron, copper and cobalt in food samples has been established. The method was based on the chromogenic reaction of the three metal ions and 2- (5-Bromo-2-pyridylazo)-5-diethylaminophenol, 5-Br-PADAP in acetic acid - sodium acetate buffer solution (pH5) with Triton X-100 and ascorbic acid. The overlapped spectra of the colored complexes were collected by charge-coupled device (CCD) - diode array detector and the multi-wavelength absorbance data was processed using partial least squares (PLS) algorithm. Optimum reaction conditions and parameters of flow injection analysis were investigated. The samples of tea, sesame, laver, millet, cornmeal, mung bean and soybean powder were determined by the proposed method. The average recoveries of spiked samples were 91.80%∼100.9% for Iron, 92.50%∼108.0% for Copper, 93.00%∼110.5% for Cobalt, respectively with relative standard deviation (R.S.D) of 1.1%∼12.1%. The sampling rate is 45 samples h−1. The determination results of the food samples were in good agreement between the proposed method and ICP-AES.