University of North Florida
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Stuart Chalk, Ph.D.
Department of Chemistry
University of North Florida
Phone: 1-904-620-1938
Fax: 1-904-620-3535
Email: schalk@unf.edu
Website: @unf

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Cold trap

Classification: Manifold component -> Cold trap

Citations 7

"Flow Injection Atomic Spectrometric Determination Of Inorganic Arsenic(III) And Arsenic(V) Species By Use Of An Aluminum-column Arsine Generator And Cold-trapping Arsine Collection"
Anal. Chim. Acta 1992 Volume 261, Issue 1-2 Pages 105-113
M. Burguera, J. L. Burguera and M. R. Brunetto, M. de la Guardia and A. Salvador

Abstract: The sample is injected into water as carrier and the solution (with or without introduction of 10% KI solution to reduce As(V)) is mixed with 5 M NaOH before passage through an electrically heated Pyrex column containing a rolled foil of metallic Al (~1 g) to reduce As(III) to AsH3. The AsH3 passes to a gas - liquid separator and is collected for 3 min in a liquid-N-cooled trap. The trap is then placed in hot water, and He is used to sweep the AsH3 into a fused-silica cell above an air - acetylene flame for AAS measurement at 193.7 nm. Analysis for As(III) and total As takes ~10 min. Optimized operating conditions are given. Interference in the determination of 1 ng of As(III) was caused by >10 ng of Ni, Be, Cr(III), Ag, Pb, Cu(II), Sn, Zr, or Fe(III). The detection limit was 0.25 µg L-1 of As(III) or As(V). The method was successfully applied to water samples from a trout fishery. A flow injection system is described for the selective determination of arsenic(III) and arsenic(V) (0.05-20 ng) in a 100 µL sample volume by hydride generation and atomic absorption spectrometry. An elec. heated aluminum column was used to generate the arsine in an alkaline medium. Recoveries averaged 97-99% for arsenic(III) and 95-98% for arsenic(V) with relative standard deviations of less than 4.3% in each instance. The detection limit was 0.25 µg L-1 (25 pg) of arsenic in both instances. This method was relatively free from interferences and was applied successfully to the determination of arsenic(III) and arsenic(V) in trout fishery water samples. The data obtained were compared with those produced by a hydride generation-cold trapping atomic absorption spectrometric detection method, using sodium tetrahydroborate(III) in hydrochloric acid. The results obtained by both methods were in close agreement, within 96-102%.
Arsenic(3+) Arsenic(5+) Arsenic, inorganic Water Spectrophotometry Spectrophotometry

"Simultaneous Determination Of Arsenic, Antimony And Selenium By Gas-phase Diode-array Molecular Absorption Spectrometry, After Preconcentration In A Cryogenic Trap"
Anal. Chim. Acta 1995 Volume 300, Issue 1-3 Pages 321-327
Susana Cabredo Pinillos, Jesús Sanz Asensio* and Javier Galbán Bernal

Abstract: Solutions of 4% NaBH4 (4 ml/min) and analyte mixture in 0.5 M HCl (35 ml/min) were passed through a mixer and to a system of two gas-liquid separators where the N2 carrier gas (20 ml/min) transferred the gaseous products to a water trap immersed in a bath of ice and salt (-10°C). The hydrides were retained in a glass U-tube in liquid N2. After trapping, the tube was removed from the cryogenic bath for > 5 min then heated for 1 min at 80°C. The hydrides were transported to a continuous-flow cell and placed in a diode-array spectrophotometer for measurement of the transient signals over the 190-250 nm range. Linear response ranges above 50 µg/l for As(III), 30 µg/l for Sb(III) and 200 µg/l for Se(IV) were obtained with detection limits of 22, 15 and 65 µg/l, respectively. Multiwavelength linear regression equations were used for the simultaneous determination of the three elements in synthetic samples and to study the effects of possible interfering species. The results were similar to those obtained by other hydride generation techniques.
Antimony Arsenic Selenium Spectrophotometry

"Online Cryogenic Trapping With Microwave Heating For The Determination And Speciation Of Arsenic By Flow Injection/hydride Generation/atomic Absorption Spectrometry"
Talanta 1998 Volume 45, Issue 3 Pages 531-542
J. L. Burguera*, M. Burguera, C. Rivas and P. Carrero

Abstract: An online flow injection-hydride generation/at. absorption spectrometry method was developed for the pre-concentration and selective determination of inorganic As (As(III) and As(V)) and its methylated species. The separation of the As species was performed by an automated pH-selective arsines generation technique, using Na tetrahydroborate(III) as reductant. Each arsine was cryogenically trapped in a PTFE coil, knotted and sealed inside another wider diameter tube, through which liquid N was suctioned by negative pressure. Then, based on their different b.ps., the arsine species were selectively liberated using a heating cycle of microwave radiation, followed by atomic absorption detection. A sample solution aliquot mixed with 1% citric acid was used for the determination of As(III) alone, while a 2nd sample aliquot mixed with 2 mol/L nitric acid was used for the quant. determination of total inorganic As, monomethylarsonic acid and dimethylarsinic acid. Based on 10 mL sample, the detection limits are 20-60 ng As/L, which are sufficiently low to detect the arsines-forming species in natural waters. These values are negative affected by the reagents purity and background noise due to flame flickering, but the sensitivity can substantially be improved by increasing sample size or running several consecutive reactions.
Arsenic(3+) Arsenic(5+) Dimethylarsenic Monomethylarsine Environmental Spectrophotometry

"A Semi-continuous Flow Method For The Trace Analysis Of Dissolved Inorganic Antimony"
Anal. Proc. 1989 Volume 26, Issue 1 Pages 32-34
A. T. Campbell and A. G. Howard

Abstract: A 5 mL sample is mixed with 0.5 mL of 1 M KI pre-reductant, and masking agents (if required), and placed in the continuous-flow system (details and diagram given). The solution is acidifed with HCl for determination of total Sb, or mixed with acetate buffer of pH 5.0 for determination of Sb(III), segmented with air, and treated with aqueous 2% NaBH4; the products are swept through a delay coil and stripped from solution in a gas - liquid separator. Stibine is condensed in a cryogenic trap at -196°C, liquid N is then removed and the trap is warmed to room temp., before atomization of stibine and AAS detection at 217.6 nm. Calibration graphs are rectilinear for up to 3 ng of Sb(III) or total Sb, with a detection limit of 24 ng L-1 of total Sb (for a 5 mL sample). Interfering ions are tabulated. The method is applied in determination of total Sb in natural water.
Antimony(3+) Antimony, total Environmental Spectrophotometry

"Determination Of Arsenic And Selenium By Hydride Generation Atomic Absorption Spectrometry (flow Injection Or Continuous-flow) Method Combined With A Hydride Collecting Trap"
Can. J. Anal. Sci. Spectrosc. 1995 Volume 40, Issue 5 Pages 117-124
Siska, R.;Borszeki, J.;Gegus, E.

Abstract: A hydride collecting cold trap hydride generation AAS method has been developed using a flow injection (FI) or a continuous-flow (CF) system, applicable to the high sensitivity determination of arsenic and selenium, characterized by a detection limit of 10^-20 pg/mL. The best relative detection limits and sensitivity for this system could be achieved using the CF operation mode. Accuracy and reproducibility of the method were investigated by the analysis of dilute solutions produced by decomposition of international CRM samples of various types. The results of the determinations agree well with the certified values. Reproducibility of the measurements is good considering especially the extreme low initial concentrations. The remarkable feature of the method is the relatively low blank value which is partly due to the use of high purity acids and reagents, and partly to the very low risk of contamination when the work is done in a closed system. Further on, several water samples were investigated by this method, the arsenic and selenium content of which could not be determined previously. Also numerous food samples having low content of As and Se were analyzed. (12 references)
Arsenic Selenium Food Water Spectrophotometry

"Online Cold-trap Hydride Collection Flow Injection Determination Of Arsenic And Antimony In Seawater"
Haiyang Xuebao 1989 Volume 9, Issue 2 Pages 255-261
Lu, Xiankun; Li, Jing; Chen, Shuzhu; Dai, Guosheng

Abstract: An automatic flow analysis system with on-line liquid nitrogen trap, hydride generation and flame-less atomic absorption spectrophotometry was presented for the determination of inorganic arsenic and antimony in seawater. The experimental conditions such as acidity of reduction reaction, the amount of sodium borohydride, the flow rate of carry gas (high purity of nitrogen) were tested and selected optimally. The limit detection of the method presented was 0.15 µg/L for arsenic and 0.24 µg/L for antimony. During the determination of seawater samples with levels microgram arsenic and antimony per liter the variation coefficient would be ±4% for arsenic and ±10% for antimony. The volume needed for one measurement was 9 mL for arsenic and 12 mL for antimony. The frequency of sample determination reached 20 times per hour for arsenic and 15 times per hour for antimony.
Arsenic Antimony Sea Spectrophotometry

"Determination Of Arsenic And Selenium By Injection Combined With Cold-trap Collection Of Hydride And Continuous-flow Hydride Atomic Absorption Technique"
Magy. Kem. Foly. 1996 Volume 102, Issue 3 Pages 248-256
Siska, R.;Borszeki, J.;Gegus, E.

Abstract: Continuous-flow and flow injection hydride-generation AAS methods for the determination of As and Se are described, which involve collection of hydrides in a cold trap (diagrams of manifolds given). The detection limits were 10^-20 pg/ml. The results obtained for international standards agreed with the internationally accepted values. Reproducibility was good. The methods were applied to environmental materials (food and water).
Arsenic Selenium Environmental Food Water Spectrophotometry