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1.
Ralf Eiden Ralf Falter Barbara Augustin-Castro Heinz Friedrich Sch?ler 《Fresenius' Journal of Analytical Chemistry》1997,357(4):439-441
Distillation as a way of sample digestion has been combined with on-line RP C18 preconcentration and HPLC-UV-PCO-CVAAS (high
performance liquid chromatography — ultra violet — post column oxidation — cold vapour atomic absorption spectrometry) for
the determination of methylmercury at back-ground levels in sediments, soils and fish tissue. To prove the accuracy of this
method, it was applied to sediment and fish tissue reference materials. The results correspond with the reference values within
their error ranges. Excellent recoveries (92–95%) were obtained for the sediment samples by means of the standard addition
method. The standard deviations of the sediment samples were within an acceptable range (7.2–12.5%), those of the fish samples
were substantially lower (3.4–5.0%). The detection limit is 0.04 ng/g for 1 g sample weight. 相似文献
2.
This paper summarizes several key points in applying the microwave preparation technique to the elemental analysis of aquatic
sediments and reports systematic experiments in searching for an optimal microwave preparation procedure for element analysis
in sediment samples. The determination of the elements Cu, Pb and Cd in a standard reference aquatic sediment sample (CRM
280, COMEUR) was achieved by first digesting the samples in a microwave oven equipped with PFA advanced composite vessels,
followed by AAS measurement. The influence of microwave power, digestion time, various dissolution reagents and the HF removing
conditions was studied. It has been shown that for a 0.1 g sediment sample the optimal microwave preparation conditions are:
4–5ml HNO3/HF/H2O2 as solvent, digesting time 30 min with 100% microwave power and evaporating the residual acid within 8 min in an open vessel
at 80 °C. The element recovery rates with AAS measurement can reach up to 92.4–100.6%.
Received: 23 July 1996/Revised: 23 September 1996/Accepted: 25 September 1996 相似文献
3.
For the determination of 16 PAHs in soils and sediment samples by GC/FID and GC/MS, the dynamic off-line supercritical fluid
extraction with both pure and modified carbon dioxide has been evaluated. The optimisation of extraction parameters was performed
for four individual groups of PAHs according to their number of aromatic rings (2–3 rings, 4 rings, 5 rings and 6 rings) by
varying pressure (200–510 bar), temperature (50–150 °C), extraction fluid volume (10–50 ml), and the methanol modifier concentration
(0–10%). Using a five level spherical factorial experimental design the number of experiments required for optimisation was
45. In spiked soil samples extraction efficiencies of 80–100% were achieved for the individual groups of PAHs. At the optimal
set of conditions 10–30% lower recoveries of PAHs were obtained for the standard reference material NIST SRM 1941a (marine
sediment). The largest differences between extraction recoveries of native and spiked PAHs occurred at high molecular weight
PAHs. Using SFE efficiency data for the standard reference material, cluster analysis proved that dividing the 16 PAHs into
four groups according to their number of aromatic rings was appropriate and correct.
Received: 2 February 1996/Revised: 26 November 1996/Accepted: 30 November 1996 相似文献
4.
A column preconcentration method has been established for the spectrophotometric determination of traces of nitrite using
diazotization and coupling on an naphthalene-tetradecyldimethylbenzylammonium (TDBA)-iodide (I) adsorbent. Nitrite ion reacts
with sulfanilic acid (SA) in the pH range 1.8–3.0 for the SA-1-naphthol system and in the pH range 2.3–3.2 for the SA-1-naphthylamine-4-sulfonate
system (SA-NAS system) in hydrochloric acid medium to form water-soluble colourless diazonium cations. These cations were
coupled with 1-naphthol in the pH range 1.6–4.6 and with NAS in the pH range 2.6–5.0 to be retained on naphthalene-TDBA-I
packed in a column. The solid mass was dissolved from the column with 5 mL of dimethylformamide (DMF) and the absorbance measured
at 418 nm for the SA-1-naphthol system and at 485 nm for the SA-NAS system. The calibration curve was linear over the concentration
range 0.02–0.87 mg/L for SA-1-naphthol and 0.02–0.80 mg/L in the sample for SA-NAS. The molar absorptivity was calculated
to be 1.70×104 L mol-1 cm-1 for SA-1-naphthol and 1.66×104 L mol-1 cm-1 for SA-NAS. The detection limits were found to be 0.014 and 0.016 mg/L for SA-1-naphthol and SA-NAS, respectively. The preconcentration
factors were 8 and 6 for SA-1-naphthol and SA-NAS, respectively. Replicate determinations of seven sample solutions containing
6.6 μg of nitrite for SA-1-naphthol and 5.3 μg of nitrite for SA-NAS gave mean absorbances of 0.486 and 0.382 with relative
standard deviations of 0.49 and 0.58%, respectively. Interferences due to various foreign ions have been studied and the method
has been applied to the determination of 27–65 μg/L levels of nitrite in natural waters. The recovery and relative standard
deviation for water samples were 98–102% and 0.49–0.58% for both systems.
Received: 1 December 1995/Revised: 22 April 1996/Accepted: 22 April 1996 相似文献
5.
Chunshan Zhou Xingan Xiong Mingjian Wu G. Schwedt 《Analytical and bioanalytical chemistry》1997,357(7):894-896
A reversed-phase HPLC-method for the separation of mixtures of collectors for the flotation of heavy metal minerals is described.
It is based on a Nucleosil 5C18 column, isocratic elution and UV-detection at 238 nm. The mobile phase is methanol-water-5%
phosphoric acid (40:60:4, v/v). The method is applied to the determination of six collectors in aqueous solutions from flotation
processes. The relative standard deviations are 1.6–3.2% in the concentration range 2–10 mg/L. The detection limits are 1 μg/L
for 8-hydroxyquinoline, dimethylglyoxime and salicylic acid, 2 μg/L for salicylhydroxamic acid and 5 μg/L for benzenetriazol
and salicylaldoxime, respectively.
Received: 19 April 1996/Revised: 14 August 1996/Accepted: 23 August 1996 相似文献
6.
Two different mass spectrometric methods, negative thermal ionization isotope dilution mass spectrometry (NTI-IDMS) and inductively
coupled plasma mass spectrometry (ICP-MS), off-line and on-line coupled with anion exchange chromatography, have been developed
for simultaneous bromide and bromate determinations in water samples. The detection limits of these methods are in the range
of 0.03–0.09 μg/L using a 50 mL sample.The results are independent of the content of other anions, which could be demonstrated
by the analyses of six mineral waters containing chloride and sulfate of up to 160 mg/L and 1500 mg/L, respectively. Bromide
has been analyzed by the NTI-IDMS method in the range of 10–500 μg/L and bromate in the range of 1–50 μg/L with relative standard
deviations of 0.3–1.2% and 0.4–6%. Quantification for the ICP-MS method was carried out by the standard addition technique,
which resulted in relative standard deviations of 5.5% for bromide at the 500 μg/L level and of 13% for bromate at the level
of about 3 μg/L. These results are compared with those described in the literature for ion chromatographic (IC) and other
methods and those obtained in this work by IC using UV detection, which allows high concentrations of chloride in the bromate
fraction. The detection limits of this IC method are 6 μg/L for bromide and 30 μg/L for bromate. NTI-IDMS and ICP-MS therefore
fit the recommendations of the European Union (detection limit<2.5 μg/L; precision and accuracy better than 25% at the 10 μg/L
level) for methods analyzing the carcinogenic bromate much better than IC and other methods applied up to now. As a definitive
but time consuming method, NTI-IDMS is preferably applicable as a calibration technique, whereas ICP-MS, with relatively short
analysis times, due to on-line coupling with chromatography, can be used as a sensitive and powerful routine method for trace
bromide and bromate species in water samples.
Received: 5 July 1996/Accepted: 7 August 1996 相似文献
7.
Two different mass spectrometric methods, negative thermal ionization isotope dilution mass spectrometry (NTI-IDMS) and inductively
coupled plasma mass spectrometry (ICP-MS), off-line and on-line coupled with anion exchange chromatography, have been developed
for simultaneous bromide and bromate determinations in water samples. The detection limits of these methods are in the range
of 0.03–0.09 μg/L using a 50 mL sample.The results are independent of the content of other anions, which could be demonstrated
by the analyses of six mineral waters containing chloride and sulfate of up to 160 mg/L and 1500 mg/L, respectively. Bromide
has been analyzed by the NTI-IDMS method in the range of 10–500 μg/L and bromate in the range of 1–50 μg/L with relative standard
deviations of 0.3–1.2% and 0.4–6%. Quantification for the ICP-MS method was carried out by the standard addition technique,
which resulted in relative standard deviations of 5.5% for bromide at the 500 μg/L level and of 13% for bromate at the level
of about 3 μg/L. These results are compared with those described in the literature for ion chromatographic (IC) and other
methods and those obtained in this work by IC using UV detection, which allows high concentrations of chloride in the bromate
fraction. The detection limits of this IC method are 6 μg/L for bromide and 30 μg/L for bromate. NTI-IDMS and ICP-MS therefore
fit the recommendations of the European Union (detection limit<2.5 μg/L; precision and accuracy better than 25% at the 10 μg/L
level) for methods analyzing the carcinogenic bromate much better than IC and other methods applied up to now. As a definitive
but time consuming method, NTI-IDMS is preferably applicable as a calibration technique, whereas ICP-MS, with relatively short
analysis times, due to on-line coupling with chromatography, can be used as a sensitive and powerful routine method for trace
bromide and bromate species in water samples.
Received: 5 July 1996/Accepted: 7 August 1996 相似文献
8.
Pilar Bermejo-Barrera Carmen Barciela-Alonso Consuelo González-Sixto Adela Bermejo-Barrera 《Analytical and bioanalytical chemistry》1997,357(3):274-278
A method was optimized for the determination of tin in slurries of marine sediment samples using palladium-magnesium nitrate
as chemical modifier and Triton X-100 (0.1%) surfactant as stabilizer. To obtain a complete pyrolysis of the slurry sample,
two charring steps were used, the first at 480 °C and the second at 1300 °C. The precision and accuracy of the method were
studied using the Reference Material PACS-1 (marine sediment) from National Research Council Canada. The detection limit (LOD)
was 57.6 μg kg-1. The method was applied to the determination of tin in marine sediment samples from the Galicia coast.
Received: 16 February 1996/Revised: 26 March 1996/Accepted: 12 April 1996 相似文献
9.
A mixture of manganese dioxide and hydrochloric acid has been used for the accurate and precise determination of gold in
various gold-bearing matrices. Results of intermethod comparison studies, F-test on variances, Mann-Whitney U-test, Spearman
rank correlation and regression analyses are presented. The recommended method can be applied to a quality control programme
and for the evaluation of reference materials. Various standard reference materials (SRM) of diverse matrices have been examined
to check the validity of the method and the results were found to be in very good agreement with the certified data. Sample
decomposition is straight forward [1–10 g sample (roasted at 600–700 °C)+5 g of MnO2+30 mL of 2 mol/L HCl]. Gold is coprecipitated with potassium tellurite using tin (II) chloride solution. The precipitate
is extracted into toluene and finally stripped back into aqua-regia solution for final nebulization into an air-acetylene
flame for atomic absorption spectrophotometry. The method is very simple and easily adaptable, and more convenient than conventional
methods involving aqua regia or a hydrobromic acid-bromine water mixture.
Received: 23 October 1995/Revised: 18 March 1996/Accepted: 23 March 1996 相似文献
10.
An automated flow injection procedure for the determination of anionic surfactants with two-step extraction was developed,
based on the official methylene blue method. A washing step was used for on-line treatment of the extracted products with
methylene blue to eliminate interferences. An improved gravitational phase separator was used to overcome the limitations
of the membrane separator, and an effective separation of the two phases was performed by gravity separation in a conical
cavity constructed of PTFE and stainless steel. Use of PTFE pump tubing allowed reliable and reproducible withdrawal and propulsion
of organic extractant at low flow-rates. The calibration graphs were linear up to 6.0 mg/l of sodium dodecyl sulfonate in
aqueous solution when 100 μl of sample was injected, a relative standard deviation of 4.6% (n=7) was achieved. The recoveries
of the procedure were in the range of 89–107%. The results obtained for anionic surfactants in waste water samples agreed
well with those obtained by the standard methylene blue batch method.
Received: 1 December 1995/Revised: 1 April 1996/Accepted: 9 April 1996 相似文献
11.
S. Panadero A. Gómez-Hens D. Pérez-Bendito 《Analytical and bioanalytical chemistry》1997,357(1):80-83
The stopped-flow mixing technique was used to develop a simple and fast kinetic method for the determination of carminic
acid based on its inhibitory effect on the fluorescence intensity of the europium(III)- diphacinone-ammonia system in the
presence of Triton X-100. Analytical data can be obtained within 10 s after the reactants are mixed, which minimizes manipulation
and enables the ready application of the proposed method to routine analyses for carminic acid in orange soft drinks. The
dynamic range of the calibration graph was 0.5–15 μg ml-1 and the relative standard deviation less than 4%. The analytical recoveries obtained by applying the method directly to the
analysis of samples ranged from 90.0 to 111.8%.
Received : 11 November 1995/Revised: 2 February 1996/Accepted: 6 February 1996 相似文献
12.
Determination of lead traces in water and liqueurs by derivative atom trapping flame atomic absorption spectrometry 总被引:3,自引:0,他引:3
H. Sun Li-li Yang De-qiang Zhang Wei-Xiao Wang Jian-min Sun 《Fresenius' Journal of Analytical Chemistry》1997,358(5):646-651
A new method for the direct determination of lead traces using derivative atom trapping flame atomic absorption spectrometry
(DAT-FAAS) with an improved water-cooled stainless steel trapping equipment in an air-acetylene flame was investigated. The
optimum conditions concerning the sensitivity were studied. For a 1 min collection, the characteristic concentration (given
as derivative absorbance of 0.0044) and the detection limit (3s) were 1.4 ng/mL and 0.27 ng/mL, respectively. This is 361
and 74-fold better than those of the conventional flame atomic absorption spectrometry (FAAS) and comparable to those of graphite
furnace atomic absorption spectrometry (GFAAS). The detection limit and sensitivity of DAT-FAAS for a 3 min collection time
were 2 and 3 orders of magnitude higher than those of conventional FAAS. The present method was applied to the determination
of lead in water and liqueur samples with a recovery range of 94–108% and a relative standard deviation of 3.5–5.6%.
Received: 10 January 1996/Revised: 9 December 1996/Accepted: 20 December 1996 相似文献
13.
Stella T. Giroussi Anastasios N. Voulgaropoulos Aristomenis Ayiannidis 《Analytical and bioanalytical chemistry》1997,357(4):429-432
A selective, sensitive and reliable voltammetric method for the simultaneous determination of Cu and Mo is developed. Both
metals form complexes with 8-hydroxyquinoline (oxine). Mo gives two reduction peaks with oxine in acidic chloride media at
−0.52 V and −0.58 V, while copper exhibits only one at −0.14 V. Common heavy metals do not interfere at all. The limit of
detection is 0.29 ng/ml for Mo and 0.14 ng/ml for Cu after preconcentration on the hanging mercury drop electrode for 30 s
at −0.2 V. The R.S.D. at a concentration level of 10 ng/ml is 3.8% for Cu and 5.3% for Mo. The method is applied to different
biological samples.
Received: 15 January 1996/Revised: 11 April 1996/Accepted: 16 April 1996 相似文献
14.
A successful flow-through system was developed for trace analysis of copper using DPASV with a glassy-carbon electrode. Periodical
chemical regeneration of the electrode with a 1 mol/L NaOH solution increased sensitivity and precision. The method was shown
to be applicable with a detection limit of 0.56 μg/L, with a determination time of less than 7 min per measurement (without
deaeration time). The drawback of the system is the 10 min deaeration time. The system gave an accuracy of 0.090±0.005% for
a certified reference material of low alloy steel containing 0.090±0.004% Cu. Applicability to various fresh water samples
with a Cu content between 1.57 and 13.11 μg/L with an RSD<2.36% is illustrated.
Received: 11 March 1996/Revised: 1 July 1996/Accepted: 4 July 1996 相似文献
15.
A successful flow-through system was developed for trace analysis of copper using DPASV with a glassy-carbon electrode. Periodical
chemical regeneration of the electrode with a 1 mol/L NaOH solution increased sensitivity and precision. The method was shown
to be applicable with a detection limit of 0.56 μg/L, with a determination time of less than 7 min per measurement (without
deaeration time). The drawback of the system is the 10 min deaeration time. The system gave an accuracy of 0.090±0.005% for
a certified reference material of low alloy steel containing 0.090±0.004% Cu. Applicability to various fresh water samples
with a Cu content between 1.57 and 13.11 μg/L with an RSD<2.36% is illustrated.
Received: 11 March 1996/Revised: 1 July 1996/Accepted: 4 July 1996 相似文献
16.
Seven rain and 2 snow samples collected in October and November 1993 were analyzed by GFAAS. Manganese concentrations ranging
from 0.3 to 11.3 μg/L were found. pH-values (4.04–4.89, mean 4.52) and redox potentials (528–665 mV, mean 581 mV) were additionally
determined. This is important with respect to a qualified specification of Mn in atmospheric samples. A 0.45 μm-filtration
of the samples prior to GFAAS-analysis showed the same manganese concentrations in the filtrate as in the unfiltered samples.
Hence, the amount of solid Mn species in the investigated samples is negligible. For an examination of the oxidation state
of Mn some investigations concerning the stability of Mn(III) were carried out. They indicated that Mn(III) is unstable under
atmospheric conditions. For checking whether all the manganese in rainwater exists as Mn(II), a sensitive IC method for the
detection of Mn(II) was developed. By adapting a photometric procedure based on the oxidation of Leucomalachite Green (LMG)
to Malachite Green (MG) by permanganate (MnO-
4) to the IC-flow-through-system, a limit of determination of 1 μg/L Mn(II) could be achieved. A comparison of the IC measurements
with GFAAS-results of the filtered samples showed agreeing results. Thus, manganese in rainwater and snow exists entirely
as soluble Mn(II).
Received: 24 May 1996/Revised: 7 July 1996/Accepted: 14 July 1996 相似文献
17.
Seven rain and 2 snow samples collected in October and November 1993 were analyzed by GFAAS. Manganese concentrations ranging
from 0.3 to 11.3 μg/L were found. pH-values (4.04–4.89, mean 4.52) and redox potentials (528–665 mV, mean 581 mV) were additionally
determined. This is important with respect to a qualified specification of Mn in atmospheric samples. A 0.45 μm-filtration
of the samples prior to GFAAS-analysis showed the same manganese concentrations in the filtrate as in the unfiltered samples.
Hence, the amount of solid Mn species in the investigated samples is negligible. For an examination of the oxidation state
of Mn some investigations concerning the stability of Mn(III) were carried out. They indicated that Mn(III) is unstable under
atmospheric conditions. For checking whether all the manganese in rainwater exists as Mn(II), a sensitive IC method for the
detection of Mn(II) was developed. By adapting a photometric procedure based on the oxidation of Leucomalachite Green (LMG)
to Malachite Green (MG) by permanganate (MnO-
4) to the IC-flow-through-system, a limit of determination of 1 μg/L Mn(II) could be achieved. A comparison of the IC measurements
with GFAAS-results of the filtered samples showed agreeing results. Thus, manganese in rainwater and snow exists entirely
as soluble Mn(II).
Received: 24 May 1996/Revised: 7 July 1996/Accepted: 14 July 1996 相似文献
18.
The integration of an urease reactor into a gas diffusion flow injection system was investigated for the determination of
urease inhibitors. The enzyme was immobilized by entrapping in polyacrylamide gel. Besides copper and silver ions mercury
ions inhibit the conversion of urea to carbon dioxide and ammonia catalysed by urease. The pH change of the carrier solution
caused by the ammonia released was measured potentiometrically with a pH electrode. The inhibition behaviour of Hg(II) ions
was investigated. A linear range from 2 to 20 μg L-1 Hg(II) was obtained after a 90 s inhibition, with a correlation coefficient of r=0.9997. The relative standard deviation
was 1.4% for five measurements of 2 μg L-1Hg(II). A sample frequency of 7 h-1 was achieved. The inhibited enzyme can be reactivated. The method was applied to the determination of Hg(II) in two drinking
water samples.
Received: 16 April 1996/Revised: 3 June 1996/Accepted: 11 June 1996 相似文献
19.
M. A. Kabil S. E. Ghazy A. A. El-Asmy Y. E. Sherif 《Analytical and bioanalytical chemistry》1997,357(4):401-404
A sensitive and selective flotation procedure for the separation of microamounts of Co(II), Ni(II) and Cu(II) separately
or in admixture is described. The maximum separation rate (∼1) for 0.1 mmol/L of each analyte is achieved using 1 mmol/L of
both oleic acid (HOL) surfactant and 4-phenylthiosemicarbazide (HPTS) as a collector in the pH range 6–7. A method for the
simultaneous separation and microdetermination of the analytes is elaborated, based on adding excess HPTS and floating the
species with HOL at pH ∼6. The filtrate (which is clear brownish-yellow) obtained from the scum is used for the spectrophotometric
determination of Co(II) at 350 nm. The formation constants of 1:1 and 1:2 [Co(II):HPTS] species are 6.9×105 and 1.22×1010 L mol-1, respectively. Beer’s law is obeyed up to 9 μg/mL of Co(II) with a molar absorptivity of 1.15×104 L mol-1 cm-1. The precipitate in the scum layer is quantitatively collected, dissolved in aqua regia and aspirated directly into the flame
for the (AAS) determination of Ni and Cu. The procedure is successfully applied to some natural water samples. A mechanism
for the separation of the analytes is proposed.
Received: 23 January 1996/Revised: 1 April 1996/Accepted: 9 April 1996 相似文献
20.
A. N. Araújo Joan Gracia Jose´ L. F. C. Lima Manel Poch M. Lu´cia M. F. S. Saraiva 《Analytical and bioanalytical chemistry》1997,357(8):1153-1156
A procedure is described for the colorimetric determination of iron in infant fortified formulas based on sequential injection
analysis (SIA). Iron(III) complexation with thiocyanate is used as colour developing reaction. The system enables the determination
of iron in the samples (after digestion by dry ashing and treatment with 0.2 mol/L nitric acid in the range of 0.50–20.0 mg/L,
consuming 140 μL of the sample and 8 mg thiocyanate per determination. The reactor geometry and the adjustment of the ionic
content of the calibration solutions is important for the accuracy of the results. A regression line according to the equation
[Fe(III) (mg/L)]SIA=−0.3(±0.4)+1.03(±0.04) [Fe(III) (mg/L)]FAAS was obtained after comparative analysis of a set of 12 samples. The measurement rate was 34 s, thus allowing to analyze 100
samples per hour with a relative standard deviation lower than 2%.
Received: 30 July 1996/Revised: 1 October 1996/Accepted: 4 October 1996 相似文献