Calibration by the gradient ratio-standard addition method in flow injection flame atomic absorption spectrometry

Effect of Surfactants and of Ultrasonic Mixing in the Determination of Calcium, Magnesium, Copper and Zinc in Whole Blood by Flow Injection Flame Atomic Absorption Spectrometry

Flow injection flame atomic absorption spectrometry for slurry atomization. Determination of iron, calcium and magnesium in samples with high silica content

A novel simple sensitive and effective on-line flow injection column preconcentration platform using poly-tetrafluoroethylene turnings as sorbent was developed prior to flame atomic absorption spectrometric (FAAS) determination of palladium in vehicle exhaust catalysts, hydrogenation catalysts and environmental water samples. The method is based on the sorption of palladium(II)-diethyldithiophosphate, which was found to be more effective than dithiocarbamate ones. Methyl isobutyl ketone (MIBK) was used as eluent prior atomisation and quantification. All parameters like pH, DDPA concentration, flow rates, preconcentration time that affect the sensitivity of the method as well as interferences of other metals were investigated in detail. The enhancement factor calculated as 114 for 60 s preconcentration time while the sampling frequency as 40 h−1. The detection limit was 0.9 μg L−1 and the relative standard deviation (RSD) was 2.8% at 20.0 μg L−1 concentration level. The accuracy of the proposed method was estimated by analysing certified reference material and spiked environmental samples. The analytical features of the method were compared with other on-line column preconcentration methods reported in the literature.

A simple and convenient method based on cloud point extraction was proposed for the determination of copper.The extraction was carried out in the presence of 2-[(2-mercaptophenylimino)methyl]phenol (MPMP) as the chelating ligand and octylphenoxypolyethoxyethanol (Triton X-114) as the non-ionic surfactant.After phase separation, the surfactant rich phase containing the complex was diluted with 1.0 mol L -1 solution of HNO 3 in methanol and the analyte concentration was determined by flow injection flame atomic absorption spectrometry.Under the optimum conditions, an enhancement factor of 81 was obtained for the preconcentration of copper with 25 mL sample solution.The calibration graph was linear in the range of 1-150 µg L -1 , the relative standard deviation (RSD) for ten replicate determinations at 80 µg L -1 Cu level was 1.8 %, and the limit of detection (3 s) and quantification (10 s) were 0.15 and 0.50 μg L -1 respectively.The accuracy of method was confirmed by analysis of certified reference materials and recovery experiments.The proposed method was successfully applied to the determination of copper in rice flour and water samples.(doi: 10.

Poly(etheretherketone)-turnings a novel sorbent material for lead determination by flow injection flame atomic absorption spectrometry and factorial design optimization

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 (acacapyrH2) 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 (r2) of 0.9991 and enhancement factor of 195 for cadmium. The method was very sensitive with the detection limit (defined as 3Sb/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.

Standard additions in flow injection analysis with atomic absorption spectrometry

Standard additions in flow injection analysis based on merging zones and gradient exploitation: application to copper determination in spirits

A simple, environmentally friendly, and efficient dispersive liquid-liquid microextraction method combined with microsample injection flame atomic absorption spectrometry was developed for the separation and preconcentration of Cu(II). 2-(5-Bromo-2-pyridylazo)-5-(diethylamino)phenol (5-Br-PADAP) was used to form a hydrophobic complex of Cu(II) ions in the aqueous phase before extraction. To extract the Cu(II)-5-Br-PADAP complex from the aqueous phase to the organic phase, 2.0 mL of acetone as a disperser solvent and 200 microL of chloroform as an extraction solvent were used. The influences of important analytical parameters, such as the pH, types and volumes of the extraction and disperser solvents, amount of chelating agent, sample volume, and matrix effects, on the microextraction procedure were evaluated and optimized. Using the optimal conditions, the LOD, LOQ, preconcentration factor, and RSD were determined to be 1.4 microg/L, 4.7 microg/L, 120, and 6.5%, respectively. The accuracy of the proposed method was investigated using standard addition/recovery tests. The analysis of certified reference materials produced satisfactory analytical results. The developed method was applied for the determination of Cu in real samples.

Analysis of samples subject to physical and chemical interferences can greatly enhance the learning experience in instrumental analysis and environmental chemistry laboratories. This article describes a project-based experience in which students analyze simulated hazardous waste samples (carbonated beverages) for calcium by six techniques: (i) flame atomic absorption spectroscopy (FAAS) using external standard calibration, (ii) FAAS using external standard calibration with a releasing agent (Sr), (iii) FAAS using standard addition, (iv) FAAS using standard addition with a releasing agent (Sr), (v) ethylenediaminetetraacetic acid (EDTA) titration, and (vi) Ca-ion-specific electrode. Not surprisingly, students find that these different techniques yield conflicting results and their assignment is to explain their data in the format of a peer-reviewed journal article. Students report that this series of lab experiments is challenging and highly rewarding. Laboratory experiences such as this one should significantly improve the student's ability to analyze problematic samples and interpret experimental data.

In this study, we prepared a poly(3,4-ethylenedioxythiophene) (PEDOT) modified electrode by the electropolymerization of 0.01 M 3,4-ethylenedioxythiophene at a screen-printed electrode (SPE) in the presence of 0.1 M LiClO4 and 5 mM hydroxypropyl-β-cyclodexdrine. Many bio-interests were selected as test analytes. Electrochemical oxidation of cysteine in various pH buffer solutions (pH 2.0 ~12.0) was conducted at the SPE/PEDOT modified electrodes. Cyclic voltammetric studies showed that the SPE/PEDOT modified electrodes possessed great catalytic activity toward cysteine oxidation, and the best catalytic responses occurred in pH 6.0 buffer solution. Flow injection analysis (FIA) coupled amperometric detection was used in order to decrease detection limit. The FIA conditions were examined and the FIA signals were optimized. A linear calibration plot was obtained for 0.05-200 μM cysteine with a slope of 0.0527 μA/μM. The detection limit (S/N = 3) was 0.03 μM. The relative standard deviation was 1.44, 1.77, 2.88% for 3 continuous injection of 0.5, 20, 200 μM cysteine standards, respectively. Determination of cysteine in real sample was conducted using the same approach. We prepared three real samples, root beer syrup, human urine, and aspirin, as back ground solutions. The recovery of cysteine from real sample was determined using the standard addition method and the mean recovery was 93.5% and 105.0% for root beer syrup and aspirin, respectively. In the human urine real sample, the cysteine oxidation current were decreased. Moreover, we discovered that the PEDOT thin film may adsorb benzoquinone (BQ) and catechol (CA) in solution. The prepared SPE/PEDOT/BQ and SPE/PEDOT/CA modified electrodes can used for electrochemical detections of AA and NADH.

The use of periodically pulsed peristaltic pumps to introduce samples in flame atomic absorption spectrometry allows the signal obtained during the sampling time to be treated with Fourier transform. In this work two applications of this methodology are presented: the standard additions method and the on-line dilution of the sample. In both cases two peristaltic pumps are used. For the standard additions method, the process is carried out in two experiments using three standards. The developed procedure has been applied to copper, calcium and chromium determination in the presence of several interferents. The RSD and accuracy were lower than ±2% and 5%, respectively. The second application permits high on-line dilutions of sample. In this case, two periodically pulsed peristaltic pumps rotate in opposite ways. This method and the use of 0.5 mm id tubes and a sampling time of 13 s, permits copper concentrations as high as 2000 µg ml−1 to be determined.

A rapid and precise assay for peroxide as ‘active oxygen’ in products, by flow injection analysis in a high pressure system with spectrophotometric detection

New complexes of Cu2+, Hg2+, and Cd2+ with a recently synthesized Schiff base derived from 2-(3-hydroxy-1-methylbut-2-enylideneamino)pyridine-3-ol were applied for their simultaneous determination with artificial neural networks. A new analytical method using principal component-feed forward neural networks (PC-FFNNs) and principal component-radial basis function networks (PC-RBFNs) was used. Spectral data was reduced using principal component analysis and subjected to ANNs. The data obtained from synthetic mixtures of metal ions were processed by PC-FFNNs and PC-RBFNs. Performances of the proposed methods were tested with regard to relative standard error of prediction. Limit of detections and limit of quantifications were determined. The results obtained by PC-FFNNs and PC-RBFNs were compared to each other. Under the working conditions, the proposed methods were successfully applied to simultaneous determination of Hg2+, Cu2+, and Cd2+ in different water and soil samples. Concentrations of metal ions in the samples were also determined by flame atomic absorption spectrometry (FAAS) and standard addition method. The amounts of metal ions obtained by the proposed methods were in good agreement with those obtained by FAAS and standard addition method.

Objective To establish a catalytic spectrophotometric method for determination of iodine in water without the use of highly toxic arsenic reagents with good precision and accuracy. Methods A new flow injection catalytic spectrophotometry method for determination of iodine in water was established by combining flow injection analysis (FIA) with a new catalytic spectrophotometry for determination of iodine with no need of arsenic reagent. The standard curve linearity, sample detection limit, precision and accuracy of different iodine content ranges(0 - 250, 0 - 1 200 μg/L) were tested. The test result was compared with that of the arsenic-based catalytic spectrophotometry recommended by the iodine deficiency disorders monitoring program in China(recommended monitoring method). Results A calibration relation of C = aA2 + bA + d (C: iodine concentration, A: measuring absorbance peak area from FIA) of the new method existed in the range of 0 - 250 and 0 - 1 200 μg/L. The linear correlative coefficient were both 0.999 9. The detection limit for iodine in water was 0.3 μg/L. The FIA peak shape of the sample tube with the lowest content is determined, and the sensitive iodine signal is detected. The water samples with different iodine content ranges were determined in parallel for 6 times, and the coefficient of variation (CV) was 0.2% - 2.7%; the recoveries ranged from 95.0% to 105.0%, and the total average recovery was 100.3%. The measured values of water iodine standard material GBW 09113e [(8.2 ± 1.2) μg/L] and GBW 09114d [(62.0 ± 6.0) μg/L] in the standard curve of different iodine contents were all within the uncertainty range of the given value. There was no significant difference between the results of recommended monitoring method and the new method(t = 0.781, P > 0.05). Conclusions The new method for measuring water iodine has a wide standard curve range, high sensitivity, and good precision and accuracy. The instrument is easy to operate, and no need for toxic arsenic reagent. The method is a reliable method for water iodine detection. Key words: Iodine; Water; Arsenic; Flow injection analysis; Catalytic spectrophotometry