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1.
《Analytical letters》2012,45(11):1921-1930
This paper describes a simple and sensitive method for the determination of manganese in human urine by graphite furnace atomic absorption spectroscopy (GFAAS), which includes sample preparation by microwave digestion. Matrix modifier combinations, the digestion power, pyrolysis, and atomization temperatures were optimized. A mixture of 5.0 µg Pd(NO3)2 and 3.2 µg Mg(NO3)2 modifier presented the best performance. The optimal temperatures for pyrolysis and atomization were 1500°C and 1950°C, respectively. The GFAAS method was compared to inductively coupled plasma–mass spectrometry (ICP–MS) for the determination of manganese in urine. Analytical figures of merit for GFAAS and ICP–MS were: accuracy (3.46%, 2.19%), precision (3.61%, 5.84%), LOD (0.109 µg · L?1, 0.015 µg · L?1), LOQ (0.327 µg · L?1, 0.045 µg · L?1), and recovery (80–100%, 74–89%). Both methods were employed for the determination of Mn in urine and the results were compared statistically.  相似文献   

2.
《Analytical letters》2012,45(5):806-821
Abstract

The voltammetric behavior of rosiglitazone was studied using direct current (DCt), differential pulse (DPP), and alternating current (ACt) polarography. The drug manifests cathodic waves over a pH range of 2–11.2. In Britton‐Robinson buffer (BRb; pH 4), the diffusion current–concentration relationship was found to be rectilinear over a range of 4–24 µg · mL?1 and 0.1–16 µg · mL?1 using DCt and DPP modes, respectively, with minimum limits of detection (LOD) of 0.15 µg · mL?1 and 0.07 µg · mL?1 using the DCt and DDP modes, respectively. The diffusion‐current constant (I d) was 6.63±0.03 (n=5). The proposed method was successfully applied to the determination of the studied compound both in pure form and in formulations. The mean percentage recoveries in tablets were 100.09±1.18 and 100.85±0.88 (n=5) using DCt and DPP modes, respectively. Furthermore, the proposed method, adopting the DPP mode, was applied to the determination of rosiglitazone in spiked human plasma and the obtained mean percentage recoveries were 99.14±3.29 (n=4).  相似文献   

3.
《Analytical letters》2012,45(18):3417-3429
Abstract

A flow‐injection spectrophotometric procedure was developed for determining N‐acetylcysteine in pharmaceutical formulations. The sample was dissolved in deionized water and 400 µl of the solution was injected into a carrier stream of 1.0×10?2 mol l?1 sodium borate solution. The sample flowed through a column (70 mm length×2.0 mm i.d.) packed with Zn3(PO4)2 immobilized in a polymeric matrix of polyester resin and Zn(II) ions were released from the solid‐phase reactor because of the formation of the Zn(II) (N‐acetylcysteine)2 complex. The mixture merged with a stream of borate buffer solution (pH 9.0) containing 5.0×10?4 mol l?1 Alizarin red S and the Zn(II)Alizarin red complex formed was measured spectrophotometrically at 540 nm. The analytical curve was linear in the N‐acetylcysteine concentration range from 3.0×10?5 to 1.5×10?4 mol l?1 (4.9 to 24.5 µg ml?1) with a detections limit of 8.0×10?6 mol l?1 (1.3 µg ml?1). The relative standard deviations (RSDs) were smaller than 0.5% (n=10) for solutions containing 5.0×10?5 mol l?1 (8.0 µg ml?1) and 8.0×10?5 mol l?1 (13.0 µg ml?1) of N‐acetylcysteine, and the analytical frequency was 60 determinations per hour. A paired t‐test showed that all results obtained for N‐acetylcysteine in commercial formulations using the proposed flow‐injection procedure and a comparative procedure agreed at the 95% confidence level.  相似文献   

4.
《Analytical letters》2012,45(5):932-941
The heavy metal content was investigated for six mushroom species native to Jordan. Metal (Cu, Pb, Cd, Fe, Zn, Mn, Ni, and Co) content in soil substrate and their relation to metal concentrations in mushroom and underlying soil were determined by flame and graphite furnace atomic absorption spectrometry. Mushroom species and soil were collected from different places in Jordan. The highest Cu level was 51.84 µg g?1 for the species Lepista nuda; whereas, the lowest Cu level was found to be 18.51 µg g?1 in Calvatia utriformis. Among the wild mushrooms, the highest Pb level was found as 4.81 µg g?1 in Bovista plumbea, whereas the lowest Pb concentration was 2.01 µg g?1 in Calvatia utriformis. The highest Cd level was determined as 1.9 µg g?1 for Lepista nuda, whereas the lowest Cd level was 0.58 µg g?1 for the species of Polyporus frondosus. The highest Zn level was 58.77 µg g?1 for the species of Lepista nuda and the lowest Zn concentration was found 35.98 µg g?1 in Calvatia utriformis. The highest Fe level was found as 317 µg g?1 in Lepista nuda, whereas the lowest Fe concentration was 211.7 µg g?1 in Calvatia utriformis. The highest Mn content was 36.55 µg g?1 for Russula delica, whereas the lowest Mn level was 24.5 µg g?1 for the species Bovista plumbea. The highest Ni content was found as 12.65 µg g?1 for Russula delica, whereas the lowest Ni level was 0.17 µg g?1 for Bovista plumbea. The highest Co content in the tested mushrooms was found as 3.5 µg g?1 for the species of Agaricus bisporus, whereas the lowest Co level was 0.85 µg g?1 for Polyporus frondosus. The results indicated that, in general, heavy metal contents in all mushroom species were lower than the underlying soil substrates except for some mushroom species.  相似文献   

5.
《Analytical letters》2012,45(1-3):271-283
A flow injection system is proposed for catalytic kinetic spectrophotometric determination of trace iron(II + III). The involved reaction is based on the catalytic effect of iron(III) on oxidation reaction of xylenol orange by potassium bromate to form a blue-violet complex. Iron(II) is also determined, being oxidized to iron(III) by potassium bromate. The calibration graph is linear in the range of 0.02–10.0 µg l?1 and 10.0–1100 µg l?1. The relative standard deviation is 1.5% for 4.0 µg l?1 iron(III) and 2.3% for 60.0µg l?1 iron(III) (n = 11). The presented system was applied successfully to the determination of iron in natural waters.  相似文献   

6.
《Analytical letters》2012,45(2):356-366
A fast, simple and sensitive method for determining of lead in hair dyes using graphite furnace atomic absorption spectrometry with slurry sampling was developed. Multivariate optimization was used to establish optimal analytical parameters through a fractional factorial and a central composite design. The samples were submitted for direct analysis without prior digestion and were diluted in 2.5% v/v HNO3 and 1.5% v/v H2O2. Palladium (chemical modifier) and rhodium (permanent modifier) were selected from several potential modifiers. The optimal conditions were a pyrolysis time of 10 s (liquid and dust dyes) 20 s (cream dyes), a pyrolysis temperature of 789°C (liquid dyes) or 750°C (cream and dust dyes) and an atomization temperature of 1800°C for all dyes. Under optimum conditions, the calibration graph is linear in the 1.50–50.0 µg L?1 concentration range, with a detection limit of 0.33, 0.44, and 0.39 µg L?1 for liquid, dust, and cream hair dyes, respectively. The relative standard deviation ranged from 1.63 to 4.56%. The recovery rate ranged from 85 to 108%, and no significant differences were found between the results obtained with the proposed method and the microwave decomposition analysis method of real samples. The concentration ranges obtained for lead in the hair dyes samples were 1.00–11.3 µg L?1 for liquid dyes, 14.0–100 µg kg?1 for dust dyes, and 19.9–187 µg kg?1 for cream dyes.  相似文献   

7.
《Analytical letters》2012,45(17):2747-2757
Abstract

Brazilian sugarcane spirits were analyzed to elucidate similarities and dissimilarities by principal component analysis. Nine aldehydes, six alcohols, and six metal cations were identified and quantified. Isobutanol (LD 202.9 µg L?1), butiraldehyde (0.08–0.5 µg L?1), ethanol (39–47% v/v), and copper (371–6068 µg L?1) showed marked similarities, but the concentration levels of n-butanol (1.6–7.3 µg L?1), sec-butanol (LD 89 µg L?1), formaldehyde (0.1–0.74 µg L?1), valeraldehyde (0.04–0.31 µg L?1), iron (8.6–139.1 µg L?1), and magnesium (LD 1149 µg L?1) exhibited differences from samples.  相似文献   

8.
《Analytical letters》2012,45(13):2089-2101
Abstract

A procedure for the spectrophotometric determination of aluminum traces in water using a flow injection (FI) preconcentration system has been proposed. The flow system was made up of a peristaltic pump, an injector‐commutator, and a minicolumn filled with 300.0 mg of Amberlite IR‐120 cationic exchange resin. After the preconcentration step, aluminum was eluted by a 4.0 mol l?1 HCl solution. In a second stage, out of the flow system, the eluate was neutralized with a 4.0 mol l?1 NaOH solution. The aluminum was submitted to the reaction with eriochrome cyanine to form a chelate in solution buffered to pH 5.85, according to the Standard Method's procedure with some modifications, and this was followed by spectrophotometric detection. Chemical and flow variables were studied in the preconcentration system. The precision of the proposed method was calculated for a solution containing 46.8 µg l?1 of Al(III), when 40.0 ml of solution were preconcentrated (n=7), and their respective relative standard deviation (RSD) was 1.8%. The detection limit obtained was 1.7 µg l?1 of Al(III) (sample volume=40.0 ml). The proposed method was successful in determining aluminum in water certified reference material.  相似文献   

9.
《Analytical letters》2012,45(15):2508-2521
Porous polyaniline coatings doped with different counter ions were electrodeposited on the surface of stainless steel wires using controlled potentiostatic coulometry. Prior to electropolymerization, the stainless steel wires were chemically etched to improve subsequent immobilization of the polyaniline coatings on the substrate and to increase the effective surface area. Porous polyaniline coatings doped with sulfate, nitrate, and perchlorate counter ions were employed for solid-phase microextraction (SPME) of 2-chlorophenol, 2,4-dichlorophenol, triclosan, and 2,4-dichlorophenoxyacetic acid coupled to high-performance liquid chromatography. The results demonstrated that the perchlorate doped polyaniline coating exhibited the highest extraction efficiency for 2-chlorophenol, 2,4-dichlorophenol, and triclosan at pH 5.0, indicating that the extraction capability was modified by introducing different counter ions into the coatings. As a result, the perchlorate doped polyaniline coated fiber was further used for the optimization of extraction condition s . The method provided linear dynamic ranges over 2 to 4 orders of magnitude. The limits of detection were 0.006 µg · L?1, 0.005 µg · L?1, and 0.040 µg · L?1 for 2-chlorophenol, 2,4-dichlorophenol, and triclosan, respectively. The precision expressed as the relative standard deviation ranged from 2.20% to 5.04% for spiked water at 10 µg · L ?1 (n = 5) and the fiber to fiber reproducibility was between 3.27% and 5.91% (n = 5). The method was successfully applied to the determination of chlorophenolics in real water samples. The recoveries of chlorophenolics in spiked water at 5.0 µg · L?1 were between 99.60% and 108.7% with relative standard deviations between 3.24% and 5.47%.  相似文献   

10.
《Analytical letters》2012,45(14):2673-2682
Abstract

This work describes an analytical methodology for the determination of nitrite ions in aqueous solutions using boron‐doped diamond electrodes and square wave voltammetry associated with ultrasound radiation. The nitrite ions were oxidized to nitrate ions in Britton‐Robinson buffer solutions 0.1 M, pH 2.0 at 1.0 V versus Ag/AgCl. The voltammetric response of nitrite in the presence of ultrasound showed a peak current five times higher than the obtained in silent conditions. Thus, the detection limit obtained in the presence of radiation was 17 nM (0.782 µg l?1), a small value if compared with that obtained in the absence of ultrasound: 140 nM (6.44 µg l?1).  相似文献   

11.
《Analytical letters》2012,45(16):3002-3013
Abstract

In this paper a disposable gold screen‐printed working electrode was tested for arsenic detection in aqueous solutions using Square Wave Anodic Stripping Voltammetry (SWASV). The dynamic range of the sensor and its response were characterised in standard As(III) solutions; particular efforts were devoted to optimize electrode surface conditioning and electrolyte solution composition. The detection limit was 2.5 µg l?1 using 60 s as deposition time. A portable battery‐operated device was used to demonstrate the possibility to use the sensor for on‐site analysis. Analysis of spiked samples was also performed.  相似文献   

12.
An effective method utilising pressurised fluid extraction (PFE) to simultaneously extract polycyclic aromatic hydrocarbons (PAHs) and their polar oxidation products from atmospheric particulate matter (PM) is presented. The PFE method is advantageous over the traditional Soxhlet extraction due to its lower solvent consumption (9 mL compared to 90 mL) and shorter extraction time (15 min versus 18 h). Seventy compounds including PAHs and polar PAH oxidation products containing carbonyl (oxy-PAHs), hydroxyl (hydroxy-PAHs), and carboxylic acid (carboxy-PAHs) groups were targeted in the extraction of two different PM matrices: wood smoke (WS) and diesel exhaust (DE) PM. The PFE method was optimised and then compared to Soxhlet extraction for both PM matrices. The overall amounts of PAHs and their derivatives extracted from WS PM were slightly higher for the optimised PFE method (1849 ± 21 and 1863 ± 25 µg g?1 with dichloromethane (DCM) and methanol (MeOH), respectively) than those obtained with Soxhlet extraction (1726 ± 33 and 1769 ± 22 µg g?1 with DCM and MeOH, respectively). For DE PM (standard reference material (SRM) 2975) the overall amounts extracted by both methods were similar (average of 165 ± 6 µg g?1), agreeing with previously published values. The detailed evaluation of extraction efficiencies for WS PM showed similar amounts for unfunctionalised PAHs (1100 µg g?1) for both methods and solvents. For DE PM the mass yields for PAHs using PFE with DCM (62 ± 1 µg g?1) were the highest and nearly 20% higher than those obtained with MeOH (53 ± 2 µg g?1). The total mass yields of carboxy and hydroxy-PAHs from WS PM were also similar (412 ± 18 and 407 ± 11 µg g?1) for PFE and Soxhlet with MeOH, and higher than when DCM was used (371 ± 5 and 379 ± 12 µg g?1 for PFE and Soxhlet, respectively). For both matrices, the PFE yields for oxy-PAHs were higher than those obtained with Soxhlet.  相似文献   

13.
《Analytical letters》2012,45(4):570-581
Two simple, sensitive, and specific high-performance liquid chromatography and thin-layer chromatography methods were developed for the simultaneous estimation of Amlodipine besilate (AM) and Valsartan (VL). Separation by HPLC was achieved using a xTerra C18 column and methanol /acetonitrile /water/ 0.05% triethylamine in a ratio 40:20:30:10 by volume as mobile phase, pH was adjusted to 3 ± 0.1 with o-phosphoric acid. The flow rate was 1.2 mL min?1. The linearity range was 0.2 to 2 µg mL?1 for amlodipine besilate and 0.4 to 4 µg mL?1 for Valsartan with a mean percentage recovery of 99.59 ± 0.523% and 100.61 ± 0.400% for amlodipine besilate and valsartan, respectively. The TLC method used silica gel 60 F254 plates; the optimized mobile phase was ethyl acetate/ methanol / ammonium hydroxide (55:45:5 by volume). Quantitatively, the spots were scanned densitometrically at 237 nm. The range was 0.5–4.0 µg spot?1 for amlodipine besilate and 2.0–12.0 µg spot?1 for valsartan. The mean percentages recovery was 99.80 ± 0.451% and 100.61 ± 0.363% for amlodipine besilate and valsartan, respectively. The HPLC method was found to be simple, selective, precise, and reproducible for the estimation of both drugs from spiked human plasma.  相似文献   

14.
《Analytical letters》2012,45(6):1015-1030
A reliable indirect competitive enzyme-linked immunosorbent assay (ELISA) based on a new specific monoclonal antibody was developed to determine olaquindox in animal feed. The influence of several physicochemical factors (nonfat dried milk solution, organic solvent, incubation time) on the immunoassay was investigated. In the optimized system, the 50% inhibition concentration was 9.66 ± 1.81 µ g L?1. The limits of detection for porcine, chicken, and fish feed were 0.28, 0.46, and 0.48 µg kg?1. The limits of quantification were 1.00 µg kg?1 for the feed samples. The recoveries from porcine, chicken, and fish feed spiked with olaquindox were 90–104%, 77–103%, and 78–107%, respectively, with coefficients of variation (CVs) between 3.8 and 14.1%. The cross-reactivity was less than 2.08% with four structurally related compounds and no recognition of five other restricted or forbidden drugs was observed. Parallel analysis of the three spiked feed samples showed comparable results between the indirect competitive ELISA and the standard high-performance liquid chromatography method in China (R2 = 0.9985 for porcine feed, R2 = 0.9896 for chicken feed, and R2 = 0.9987 for fish feed). These data suggest that the developed indirect competitive ELISA is a specific and convenient method and is suitable for olaquindox determination in animal feed.  相似文献   

15.
《Analytical letters》2012,45(9):1891-1905
Abstract

A simple, rapid, specific, and reliable high performance liquid chromatographic assay of zaleplon in human plasma has been developed. Reversed‐phase chromatography was conducted using a mobile phase of methanol∶ammonium acetate buffer (50∶50) v/v, pH 3.2 adjusted with orthophosphoric acid, UV detection at 232 nm. After extraction from plasma by precipitation the drug was chromatographed using a C18 reversed‐phase analytical column. The average recoveries of zaleplon from spiked plasma in the concentration range from 0.005–0.2 µg/ml were 93.29%, and their respective CV% was 2.557%. Regression analysis for the calibration plot for plasma standards obtained on three different days for the drug concentrations between 0.005–0.2 µg/ml indicated excellent linearity (r>0.999) and the coefficient of variation of the slopes of the three lines was less than 2%. The limit of detection was 5 ng/ml. Analysis of variance of the data showed no detectable difference in the slopes of the three standard plots (F=3.1, P>0.01). The high correlation coefficients and the similarities in the slopes are good indications of the excellent reproducibility and linearity of the proposed method. The proposed method was applied to study the bioequivalence of a commercial product of zaleplon, using as reference standard the innovator drug product. The study was conducted by using one capsule (1×10 mg) of each of the commercial product and the reference standard in a two‐way open randomized crossover design involving 24 volunteers. The criteria used to assess bioequivalence of the products were AUC (0?∞), Cmax, tmax, t1/2, and K. The obtained values for these parameters were 0.246±0.03 µg h/ml, 0.150±0.013 µg/ml, 1 h, 1.26±0.36 h, and 0.5928±0.1732 h?1 for product A whereas, for product B they were 0.256±0.044 µgh/ml, 0.142±0.014 µg/ml, 1 h, 1.18±0.33 h, and 0.63±0.1747 h?1, respectively.  相似文献   

16.
《Analytical letters》2012,45(7):1333-1347
Abstract

A multianalyte flow‐through sensor is proposed for the simultaneous determination of aspartame (AS) and acesulfame‐K (AK) in tabletop sweeteners. The procedure is based on the transient retention of AK in the ion exchanger Sephadex DEAE A‐25 placed in the flow‐through cell of a monochannel flow injection analysis (FIA) set‐up using pH 2.70 ortophosphoric acid/sodium dihydrogen phosphate buffer 0.06 M as carrier. In these conditions AS is very weakly retained, which makes it possible to measure the intrinsic ultraviolet (UV) absorbance of first AS and then AK after desorption by the carrier itself. The applicable concentration range, the detection limit, and the relative standard deviation were the following: for AS, from 10 to 100 µg mL?1; 5.65 µg mL?1; 3.4% (at 50 µg mL?1); and for AK, between 40 and 100 µg mL?1; 11.9 µg mL?1 and 1.61% (at 50 µg mL?1). The method was applied and validated satisfactorily for the determination of AS and AK blends in tabletop sweeteners. The results were compared against an HPLC reference method.  相似文献   

17.
《Analytical letters》2012,45(10):1951-1961
Abstract

Picogram‐level gatifloxacin was determined based on its significantly catalyzed effect on myoglobin‐luminol chemiluminescence (CL) reaction in the flow injection system. The enhanced chemiluminescence intensity was linear with gatifloxacin concentration in the range from 50 ngl?1–10 µg l?1 (r2=0.9995), and the detection limit was 20 ng l?1 (3σ). At a flow rate of 2.0 ml min?1 for each line, a complete analytical process could be performed within 0.5 min, including sampling and washing, with a relative standard deviation of less than 4.0% (n=7). The proposed method was applied successfully in the determination of gatifloxacin in tablets, human serum and urine samples with the recovery from 97.4–104.5%.  相似文献   

18.
In this work, magnetic solid-phase extraction based on sodium dodecyl sulfate-coated Fe3O4 nanoparticles has been successfully applied for extraction and preconcentration of trace amounts of nystatin from water and vaccine samples prior to high-performance liquid chromatography–ultraviolet detection. Various experimental parameters affecting extraction and recovery of the analyte, such as the amount of sodium dodecyl sulfate, pH of the sample solution, salt concentration, extraction time, sample volume and desorption conditions, were systematically studied and optimized. Under optimized conditions, nystatin was quantitatively extracted. Proper linear range with good coefficient of determination, (R 2 > 0.99) and limit of detection and quantification (based on signal-to-noise ratios of 3 and 10) of 2.0 and 5.0 µg L?1, over the investigated concentration range (5–700 µg L?1), were obtained, respectively. The intra-day and inter-day relative standard deviations at 50 µg L?1 level of NYS were 1.4 and 4.5% based on six replicate determinations. The accuracy of the method was evaluated by recovery measurements on spiked samples. Suitable recoveries of 96–102 and 26–44% were achieved (at spiked levels of 50, 300 and 500 µg L?1) for water and vaccine samples, respectively.  相似文献   

19.
The voltammeric behaviour of rimsulfuron herbicide has been studied by square wave stripping voltammetry on static hanging mercury drop electrode. It exhibited a well-defined peak within the pH range of 1.0–6.0, having a maximum peak response at ?600 mV (vs.Ag/AgCl) at pH 3.0. The factors such as accumulation potential (Eacc), accumulation time (tacc), frequency (f), pulse amplitude (ΔE) and step potential (ΔEs) have been optimised. The calibration plot was a straight line in the range of 4.4–134.4 μg L?1 with a detection limit of 1.3 μg L?1. The validity of the method was assessed from the recoveries of spiked lake water, tomato juice and agrochemical formulation of Doncep®. The results of the experiments conducted for five recoveries were 48.8 ± 1.7 and 49.7 ± 1.0 μg L?1, which are very close to the rimsulfuron spiked to lake water and tomato juice (50 μg L?1), with a relative error of –2.4% and ?0.6%, respectively. The electrode reaction mechanism was also postulated.  相似文献   

20.
For determination of ultratrace amounts of plutonium in high saline groundwater, large-volume sampling and preconcentration are necessary. However, traditional co-precipitation methods, such as Fe(OH)3, Ca(OH)2–Mg(OH)2 and hydroxide-carbonate co-precipitation, are unable to meet the requirements of preconcentration of the ultratrace plutonium in high saline groundwater. In this paper, the ultratrace plutonium in high saline groundwater was concentrated by sequential co-precipitation with MnO2 and Fe(OH)3, and purified by two-stage anion-exchange separation on Dowex1 × 4 resin column. Quadrupole ICP-MS was employed for the determination of 239Pu with 242Pu spiked. After co-precipitation and purification, the major matrix elements were significantly decreased to μg mL?1 level and decontamination factor of uranium is better than 106. The detection limit for 239Pu in 50 L high saline water is 2.1 × 10?16 g L?1. Three high saline fountain samples (total dissolved solids more than 20 g L?1) from Dunhuang region of China were analyzed using this method. The concentrations of 239Pu in these samples were 0.48 ± 0.2 × 10?15, 1.40 ± 0.10 × 10?15 and 2.13 ± 0.21 × 10?15 g L?1 respectively. The recovery obtained for 7 pg of 242Pu spiked into real high saline-water samples was all above 70 %.  相似文献   

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