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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):761-777
This article reviews the use of square wave anodic stripping voltammetry for the simultaneous determination of ecotoxic metals (Pb, Cd, Cu, and Zn) on a bismuth-film (BiFE) electrode. The BiFE was prepared in situ on a glassy-carbon electrode (GCE) from the 0.1 mol L?1 acetate buffer solution (pH 4.5) containing 200 µg L?1 of bismuth (III). The addition of hydrogen peroxide to the electroanalytical cell proved beneficial for the interference-free determination of Cu (II) together with zinc, lead, and cadmium, using the BiFE. The experimental variables were investigated and optimized with the view to apply this type of voltammetric sensor to real samples containing traces of these metals. The performance characteristics, such as reproducibility, decision limit (CCa), detection capability (CCβ), sensitivity, and accuracy indicated that the method holds promise for trace Cu2+, Pb2+, Cd2+, and Zn2+ levels by employment of Hg-free GCE with SWASV. CCa, and CCβ were calculated according to the Commission Decision of 12 August 2002 (2002/657/EC). Linearity was observed in the range 20–280 µg L?1 for zinc, 10–100 µg L?1 for lead, 10–80 µg L?1 for copper, and 5–50 µg L?1 for cadmium. Using the optimized conditions, the stripping performance of the BiFE was characterized by low limits of detection (LOD). Finally, the method was successfully applied in real as well as in certified reference water samples.  相似文献   

3.
A new and sensitive precolumn derivatisation with dabsyl chloride was developed for the analysis of melamine in water samples by high-performance liquid chromatography (HPLC) with visible detection. Derivatisation with dabsyl chloride leads to improving sensitivity and hydrophobicity of melamine. Under optimum conditions of derivatisation and microextraction, the method yielded a linear calibration curve ranging from 10 to 2000 µg L?1 with a determination coefficient (R2) of 0.9952. Limit of detection (LOD) and limit of quantification (LOQ) were 2.0 and 6.0 µg L?1, respectively. The relative standard deviation per cent (RSD%) for intraday and inter-day extraction and determination at 20 and 200 µg L?1 levels of melamine was less than 8.2% (n = 6). Finally, the proposed method was successfully applied for the determination of melamine in different water samples and satisfactory results were obtained (relative recovery ≥91%).  相似文献   

4.
《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   

5.
In this paper, a novel molecularly imprinted polymer coated stir bar has been used to selectively extract naphthalene sulfonates (NSs) directly from seawater sample. 1-Naphthalene sulfonic acid (1-NS) was used as template molecule. The effects of different parameters were optimized on the extraction efficiency and the optimum conditions were established as: the absorption and desorption times were fixed, respectively, at 10 and 15 min, stirring speed was 700 rpm, pH was adjusted to 4.1, amount of NaCl was 1 mol L?1 and extraction process was performed at a temperature of 50 °C. The linear ranges were 2–250 µg L?1 for 3,6-NDS-1-OH (1-naphthol-3,6-disulfonic acid), 4–250 µg L?1 for 2-NS (2-naphthalene sulfonate) and 3–250 µg L?1 for 1-NS. The detection limits were within the range of 0.32–0.95 µg L?1. Under optimum conditions, the detection limits of the NSs were 0.84, 0.95 and 0.32 µg L?1 with the enrichment factor of 117-, 41- and 77-fold for 2-NS, 1-NS, and 6-NDS-1-OH, respectively. The repeatability of the method was satisfactory (0.53 ≤ RSD ≤6.0 %, n = 10). The method has been successfully applied for the analysis of trace amounts of three naphthalene sulfonates in seawater of Chabahar Bay.  相似文献   

6.
《Analytical letters》2012,45(3):543-554
Abstract

A spectrophotometric procedure based on hydride generation and flow analysis is proposed for determination of antimony (III) [Sb(III)] and total antimony (Sb) in pharmaceutical samples. Firstly, Sb(III) reacts with hydrogen species generated in the system, forming antimony hydride. The reaction leads to a decrease in the permanganate concentration and, hence, in the intensity of the color of this specie, which is spectrophotometrically measured at 528 nm. Total Sb is determined as Sb(III) after Sb(V) reduction using 0.02% (m/v) KI. Some parameters, such as the number of channels of the gas phase separator, injection volume, coil length, and KBH4 concentration, are investigated. The system presents a frequency of ca. 100 h?1 and precision <3.0% [expressed as relative standard deviation (RSD) of 30 measurements using a 3.0 mg L?1 Sb(III) solution]. The analytical curve ranging from 0.5 mg L?1 to 5.0 mg L?1 (r>0.998; n=5) permits limit of detection (LOD) and limit of quantification (LOQ) of 83 and 250 µg L?1. For total Sb, the accuracy is checked by atomic absorption spectrometry applying the t test and the results are in accordance at the 95% confidence level. Recovery tests are used to check the accuracy for Sb(III) determination, and the recoveries are between 95% and 105%.  相似文献   

7.
《Analytical letters》2012,45(14):1995-2005
Using 1-hexyl-3-methylimidazolium hexafluorophosphate ([C6MIM][PF6]) ionic liquid as extraction solvent, five estrogens including estrone (E1), 17β-estradiol (E2), estriol (E3), 17α -ethynylestradiol (EE2), and diethylstilbestrol (DES) in water samples were determined by dispersive liquid-liquid microextraction (DLLME) followed by high performance liquid chromatography with a photodiode array detector and a fluorescence detector (HPLC-DAD-FLD). The extraction procedure was induced by the formation of cloudy solution, which was composed of fine drops of [C6MIM][PF6] dispersed entirely into the sample solution with the help of a disperser solvent (acetone). Parameters including both extraction and disperser solvents and their volumes, extraction and centrifugal time, sample pH, and salt effect were investigated and optimized. Under the optimized conditions, 110–349 fold enrichment factors of analytes were obtained. The calibration curves were linear in the concentration range of 0.2–100 µg L?1 for E2, E3, and EE2 detected with FLD, and 1–100 µg L?1 for E1 and DES detected with DAD. The correlation coefficient of the calibration curve was between 0.9990 and 0.9997. The limits of detection (LOD, S/N = 3) for the five estrogens were in the range of 0.08–0.5 µg L?1. The relative standard deviations (RSD) for six replication experiments at the concentration of 5.0 µg L?1 were ≤5.7%. The proposed method was applied to the analysis of three water samples from different sources (river water, waste water, and sea water). The relative recoveries of spiked water samples are satisfied with 89.3–102.4% and 88.7–105.2% at two different concentration levels of 5.0 and 50.0 µg L?1, respectively.  相似文献   

8.
The possibility of using ionic liquid based chitosan sorbent for the separation and preconcentration of fluoroquinolone antibiotics (marbofloxacin, enoxacin, ofloxacin, ciprofloxacin, and enrofloxacin) has been studied. For this reason, different ionic liquids were prepared and coated on the chitosan sorbent. The conditions of the preconcentration of fluoroquinolones on a microcolumn have been optimized and the extraction efficiencies of the prepared sorbents have been compared. The compounds were eluted with 5 mL of 20% NH3 (v/v, MeOH) solution and determined by HPLC with diode array and fluorescence detector. The limits of detection were found as 4.23 µ g L?1 for marbofloxacin, and 1.09 µg L?1 for enoxacin; 3.23 × 10?3 µg L?1 for ofloxacin; 8.39 × 10?3 µg L?1 for ciprofloxacin; and 19.50 × 10?3 µg L?1 for enrofloxacin. The developed method was applied for the analysis of fluoroquinolone in milk, egg, fish, bovine, and chicken samples and the recoveries were obtained in the range 70–100%.  相似文献   

9.
The supramolecular solvent system consists of tetrahydrofuran (THF) and 1-decanol, that was used as an extraction solvent for a microextraction procedure for the preconcentration and separation of Co(II). The proposed supramolecular-based procedure was combined with microsampling flame atomic absorption spectrometry for the determination of cobalt at trace levels in water samples. N-Benzoyl-N,N-diisobutylthiourea was used to chelate Co(II) in an aqueous solution. Quantitative extraction efficiency was obtained at pH 6.5. The effects of analytical parameters including pH, amount of ligand, type, ratio and volume of supramolecular solvent, sample volume and interfering ions were investigated for optimisation of the procedure. The proposed supramolecular solvent-based microextraction procedure (Ss-ME) exhibits a limit of detection (LOD) of 1.29 µg L?1 and a limit of quantification (LOQ) of 3.88 µg L?1. The procedure was validated by addition/recovery tests and by applying TMDA 64.2 and TMDA 53.3 water certified reference materials. The microextraction method was successfully applied for the preconcentration and determination of cobalt in water samples.  相似文献   

10.
Speciation of mercury was accomplished by using a simple interface with photo-induced chemical vapour generation in a high performance liquid chromatography—atomic fluorescence spectrometry (HPLC-AFS) hyphenated system. Acetic acid and 2-mercaptoethanol in the mobile phase were used as photochemical reagent. The operating parameters were optimized to give limits of detection of 0.53 µg L?1, 0.22 µg L?1, 0.18 µg L?1 and 0.25 µg L?1 for inorganic mercury, methylmercury, ethylmercury and phenylmercury, respectively. The method was validated with the certified reference material DORM-2 and applied to the analysis of seafood samples. The HPLC-AFS hyphenated system is simple, environmentally friendly, and represents an attractive alternative to the conventional peroxothiosulfate-borohydride method.  相似文献   

11.
《Analytical letters》2012,45(17):2808-2820
A SPE-LC-MS/MS method was developed and validated for the determination of three active pharmaceutical ingredients [API A (3-([2-(diaminomethyleneamino)thiazol-4-yl]methylthio)-N′-sulfamoyl propanimid amide, API B 5-[(2 R)-2-[2-(2-ethoxyphenoxy)ethylamino]propyl]-2-methoxybenzenesulfonamide hydrochloride, API C 1-azabicyclo[2.2.2]octan-8-yl (1S)-1-phenyl-3,4-dihydro-1H-isoquinoline-2-carboxylate] in the wastewater of a chemical synthesis production facility. The SPE-LC-MS/MS method was validated in actual influent and effluent samples. Linearity, LOD, LOQ, repeatability, intermediate precision, and recovery were determined. An LOQ of 400 μg · L?1, 1.0 μg · L?1, and 6 μg · L?1, repeatability of 2.5% CV, 14.8% CV, and 11.9% CV, intermediate precision of 7.8% CV, 11.0% CV, and 8.7% CV and SPE recovery of 114%, 103%, and 91% was determined for API A, B, and C, respectively, in influent. An LOQ of 400 μg · L?1, 0.8 μg · L?1, and 6 μg · L?1, repeatability of 2.0% CV, 11.0% CV, and 10.9% CV, intermediate precision of 1.7% CV, 6.8% CV, and 10.2% CV and SPE recovery of 116%, 96%, and 115% was established for API A, B, and C, respectively, in effluent. Coefficients of correlation for each analyte were >0.9301 confirming the linearity of the method. The LC-MS/MS method was used for an on-going monitoring program for these pharmaceuticals in wastewater. The method development techniques, validation procedures, and results from real wastewater samples are presented in this paper.  相似文献   

12.
A simple and sensitive method is presented for solid phase extraction (SPE) and preconcentration of trace quantities of beryllium using octadecyl silica gel modifed with aurin tricarboxylic acid (aluminon). Beryllium is then determined by flame atomic absorption spectroscopy. Parameters affecting SPE such as pH, sample solution and eluent flow rate, type, concentration and volume of eluent, interfering ions and breakthrough volume, were investigated. Under optimal conditions, the beryllium ions were retained on the sorbent at pH 6–6.7, while 3.0 mL of 0.05 mol L?1 HNO3 is sufficient to elute the ions. The limit of detection (LOD) based on 3σ was 0.8 µg L?1 for 250 mL sample solution and 5 mL 0.05 mol L?1 HNO3 as eluent. The LOD can reach 0.1 µg L?1 for 1 L sample solution and 3 mL of 0.05 mol L?1 HNO3. The accuracy and precision (RSD %) of the method is >90% and <10%, respectively. The method was applied to the determination of beryllium in aqueous samples.  相似文献   

13.
《Analytical letters》2012,45(11):2273-2284
Abstract

A novel voltammetric method—anodic—using a bismuth/poly(aniline) film electrode has been developed for simultaneous measurement of Pb(II) and Cd(II) at low µg L?1 concentration levels by stripping voltammetry. The results confirmed that the bismuth/poly(aniline) film electrode offered high‐quality stripping performance compared with the bismuth film electrode. Well‐defined sharp stripping peaks were observed for Pb(II) and Cd(II), along with an extremely low baseline. The detection limits of Pb(II) and Cd(II) are 1.03 µg L?1 and 1.48 µg L?1, respectively. The bismuth/poly (aniline) electrode has been applied to the determination of Pb(II) in tap water samples with satisfactory results.  相似文献   

14.
《Analytical letters》2012,45(1-3):284-297
A multisyringe flow injection system for the spectrophotometric determination of bromate in water is proposed, based on the oxidation of phenothiazine compounds by bromate in acidic medium. Several phenothiazines were tested, including chlorpromazine, trifluoperazine, and thioridazine. Higher sensitivity and lower LOD were attained for chlorpromazine. Interference from nitrite, hypochlorite, and chlorite was eliminated in-line, without any changes in the manifold. The automatic methodology using chlorpromazine allowed the determination of bromate between 25 and 750 µg L?1, with LOD of 6 µg L?1, good precision (RSD < 1.6%, n = 10), and determination frequency of 35 h?1.  相似文献   

15.
An SPE-HPTLC method for simultaneous identification and quantification of seven pharmaceuticals in production wastewater was optimized and validated. The studied compounds were enrofloxacine, oxytetracycline, trimethoprim, sulfamethazine, sulfadiazine, sulfaguanidine and penicillin G/procaine. The method involves solid-phase extraction on hydrophilic-lipophilic balance cartridges with methanol and HPTLC analysis of extracts on CN modified chromatographic plates followed by videodensitometry at 254 and 366 nm. Optimization of chromatographic separation was performed by systematic variation of the mobile phase composition using genetic algorithm approach and the optimum mobile phase composition for TLC separation was 0.05 M H2C2O4:methanol = 0.81:0.19 (v/v). Linearity of the method was demonstrated in the ranges from 1.5 to 15.0 μg L−1 for enrofloxacine, 100–500 μg L−1 for oxytetracycline, 150–600 μg L−1 for trimethoprim, 300–1100 μg L−1 for sulfaguanidine and 100–400 μg L−1 for sulfamethazine, sulfadiazine and penicillin G/procaine with coefficients of determination higher than 0.991. Mean recoveries ranged from 74.6 to 117.1% and 55.1 to 108.0% for wellspring water and production wastewater, respectively. Only sulfaguanidine showed lower results. The described method has been applied to the determination of pharmaceuticals in wastewater samples from pharmaceutical industry.  相似文献   

16.
This study is aimed to develop an electroanalytical methodology using a boron-doped diamond electrode to determine simultaneously and selectively carbendazim (CBZ) and carbaryl (CAR). In previous studies using cyclic voltammetry oxidation, peaks were observed at 1.03 V (CBZ) and 1.44 V (CAR), with characteristics of an irreversible process controlled by diffusion of species, with a supporting electrolyte of BR buffer (0.1 mol L?1) and pH adjusted to 6.0. The differences between the potentials for both pesticides, about 400 mV, indicate the possibility of selective determination of CBZ and CAR. The square-wave voltammetric parameters were optimised. The best separation conditions were pH 6.0, square-wave frequency of 100 s?1, pulse amplitude of 50 mV and scan increment of 2.0 mV. These parameters were used to obtain the calibration curves of CBZ and CAR. An analytical curve was constructed in the range concentration of CBZ of 1.3 mg L?1 to 15.3 mg L?1 and CAR of 1.0 mg L?1 to 11.4 mg L?1, respectively. The limits of detection (LOD) and limits of quantification (LOQ) for CBZ were 0.40 mg L?1 and 1.30 mg L?1, respectively. For CAR, the LOD and LOQ were 0.30 mg L?1 and 1.00 mg L?1, respectively. Sensitivity values were 0.78 and 2.60 µA/mg L?1 for CBZ and CAR, respectively. The electroanalytical method was applied in Mikania glomerata infusions. The recovery values were 106.2% and 116.5% for CBZ and CAR, respectively. The results show that the developed method is suitable for application in medicinal plant samples.  相似文献   

17.
A simple and specific method for the simultaneous determination of eleutherosides B and E in powdered rhizomes of Eleutherococcus senticosus extract and in solid and liquid dietary supplements was developed and validated. E. senticosus extracts, often mixed with other plants or herbal extracts, are widely used in food supplements because of the tonic and adaptogenic activities referred to the eleutherosides B and E. In this study, samples were analyzed by a liquid chromatography-electrospray tandem mass spectrometry (LC–ESI-MS/MS) method operated in single reaction monitoring (SRM). Validation was carried out in terms of limit of detection (LOD), limit of quantitation (LOQ), linearity, precision and trueness. LOD and LOQ values were fixed at 3 μg L?1 and 10 μg L?1, respectively, whereas linearity was established within 10–1,000 μg L?1 range for both compounds. Good precision was obtained for both eleutherosides in terms of intra-day precision (RSD % lower than 4 %) and inter-day precision (RSD % lower than 6 %). Good percentage recoveries were obtained for both eleutherosides (91.5–103.6 %). Finally, the developed method was successfully applied to analyze a number of solid and liquid commercial dietary supplements containing E. senticosus extracts, also mixed with other herbal extracts.  相似文献   

18.
Persistence and dissipation of fluopicolide and propamocarb were studied on cabbage and soil as per good agricultural practices over a period of 2 years. A modified QuEChERS analytical method in conjunction with gas chromatography (GC) and GC–mass spectrometry was used for analysis of fluopicolide and its metabolite, 2,6-dichlorobenzamide, and propamocarb in cabbage and soil. The results of the method validation were satisfactory with recoveries within 74.5–100.81% and relative standard deviations 4.8–13.9% (n = 6). The limit of detection (LOD) and limit of quantification (LOQ) of both fluopicolide and 2,6-dichlorobenzamide were 0.003 µg mL?1 and 0.01 mg kg?1, respectively. The LOD and LOQ of propamocarb were 0.03 µg mL?1 and 0.1 mg kg?1, respectively. During 2013, the initial residue deposits of fluopicolide on cabbage were 0.60 and 1.48 mg kg?1 from treatments at the standard and double doses of 100 and 200 g a.i. ha?1 which dissipated with the half-life of 3.4 and 3.7 days. During 2014, the residues were 0.49 and 1.13 mg kg?1 which dissipated with the half-life of 4.2 and 5.1 days. Propamocarb residues on cabbage were 5.36 and 12.58 mg kg?1 in the first study (2013) and 4.85 and 10.26 mg kg?1 in the second study (2014) from treatments at the standard and double doses of 1000 and 2000 g a.i. ha?1, respectively. The residues dissipated with the half-life of 4–5.5 days. The preharvest interval, the time required for fluopicolide + propamocarb residues to dissipate below the maximum residue limits (notified by EU) at the standard dose, was 11.8 and 14 days during 2013 and 2014. Residue of 2,6-dichlorobenzamide was always <LOQ in cabbage. Residues of fluopicolide, 2,6-dichlorobenzamide and propamocarb were <LOQ in field soil at harvest.  相似文献   

19.
《Analytical letters》2012,45(9):1004-1015
A microwave-induced combustion (MIC) method was applied for cigarette tobacco digestion and further determination of bromide (Br), chloride (Cl), and fluoride (F) by ion chromatography (IC). Samples (up to 500 mg) were combusted at 20 bar of oxygen. Combustion was complete in less than 30 s, and analytes were absorbed in (NH4)2CO3 solutions. A reflux step, not available in other systems, was applied to improve analyte absorption. Absorbing solution with 50 mmol L?1(NH4)2CO3 was selected because it showed recovery close to 100% for samples containing spikes of halogens. Accuracy of the proposed procedure was evaluated by analysis of certified reference materials and the agreement was better than 97% for all analytes using 50 mmol L?1 (NH4)2CO3 as absorbing solution and 5 min of reflux. Temperature during combustion was higher than 1400°C and the residual carbon content was always lower than 1%. With the use of the MIC system, up to eight samples could be processed simultaneously, and a single absorbing solution was suitable for all analytes. Limits of quantification by MIC and further IC determination were 0.50, 0.20, and 0.10 µg g?1 for Br, Cl, and F, respectively.  相似文献   

20.
《Analytical letters》2012,45(13):1777-1785
A polypropylene (PP) sheet was successfully applied as an extracting medium for trace enrichment of fluoxetine (FLX) from urine samples, followed by high performance liquid chromatography-fluorescence detection (HPLC-FD). The extraction medium was a square, 1 × 1 cm2 piece of polypropylene membrane sheet that was conditioned in methanol. The extraction process was conveniently carried out using a 5 mL urine sample. After extraction, the PP sheet was withdrawn and transferred to a glass vial for performing the desorption process using 210 µL organic solvent. After complete drying, the residue was dissolved in 50 µL of methanol and an aliquot of 20 µL was, finally, injected into the HPLC system. Some important extraction parameters such as desorption solvent, pH, ionic strength, desorption, and extraction time were investigated and optimized. The linearity was studied by preconcentration of 5 mL of urine sample spiked with a standard solution of fluoxetine at the concentration range of 10–100 µg L?1. The coefficient of determination was satisfactory (r2 > 0.99). The relative standard deviations (RSD %) value under the optimized condition was found to be 10.3%. The limit of detection (LOD) and limit of quantification (LOQ) were 1.9 and 6.4 µg L?1, respectively. The developed method showed to be simple, sensitive, and adequate for the trace determination of fluoxetine in urine media.  相似文献   

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