University of North Florida
Browse the Citations
-OR-

Contact Info

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

View Stuart Chalk's profile on LinkedIn

Estuarine

Classification: Environmental -> sediment -> estuarine

Citations 4

"Determination Of Cadmium, Copper And Lead In Environmental Samples. An Evaluation Of Flow Injection Online Sorbent Extraction For Flame Atomic Absorption Spectrometry"
Anal. Chim. Acta 1994 Volume 285, Issue 1 Pages 33-43
Renli Ma, Willy Van Mol and Freddy Adams*

Abstract: Lake, estuarine or river sediment, calcareous loam soil or coal fly ash were digested in a PTFE bomb with concentrated HF and HNO3 by heating until fuming. After cooling HClO4 was added, the bomb was sealed and heated for 8 h at 150°C. Silicates were removed by repeated addition of HF and HNO3 and evaporation to dryness and the residue was dissolved in HNO3, HCl and water. The solution was injected into a FIA system and mixed with 0.2% ammonium diethyldithiophosphate in 0.1 M citric acid adjusted to pH 1 with HNO3. Following pH dependent complexion with 0.1% diethylammonium-NN-diethyldithiocarbamate in 0.1 M acetic acid (described), 50 mM citric acid was added to mask Fe(III) and Mn(II). The complexes were sorbed onto C18 bonded silica gel (40-63 µm) in a conical extraction column, eluted with methanol and analyzed by AAS; elution rates and AAS nebulizer uptake rates are discussed. Calibration graphs of peak height were linear up to 50 µg/l of Cd, 300 µg/l of Cu and 1 mg/l of Pb with detection limits of 0.8, 1.4 and 10 µg/l, respectively, with a 20 s sample loading at 8.7 ml/min.
Cadmium Copper Lead Sample preparation Spectrophotometry Sample preparation Silica gel C18 Precipitation Solid phase extraction

"Determination Of Cadmium In Environmental Samples By Hydride Generation With In Situ Concentration And Atomic Absorption Detection"
Analyst 1997 Volume 122, Issue 4 Pages 331-336
Henryk Matusiewicz, Mariusz Kopras and Ralph E. Sturgeon

Abstract: A continuous-flow AAS system for Cd determination is described. A Cd solution acidified with HCl was mixed with 1 µg/ml Co and 0.5% thiourea (and also with 0.01 M didodecyldimethyl-ammonium bromide for reaction with KBH4) and diluted to 1 mL with water. The resulting solution was aspirated at a flow rate of 1 ml/min into a continuous-flow system and merged with a stream of either 2% NaBH4 or 4% KBH4 at a flow rate of 1 ml/min. The mixture was passed through a reaction cell/gas-liquid separator maintained at 50°C and the volatile Cd species evolved were carried by an Ar stream on to the inner wall of a GF for in situ pre-concentration at 200°C. Cd analysis was by ET AAS with atomization at 1800°C for 3 s; detection was at at 228.8 nm. The detection limit was 10 ng/l Cd with KBH4 as reagent. RSD were 10^-14% (n = 10). The method was applied to several environmental and biological CRM. The results obtained agreed with the certified values.
Cadmium Spectrophotometry Heated reaction Volatile generation Reference material Phase separator Preconcentration Volatile generation

"Determination Of Arsenic, Selenium And Mercury In An Estuarine Sediment Standard Reference Material Using Flow Injection And Atomic Absorption Spectrometry"
Microchim. Acta 1995 Volume 118, Issue 3-4 Pages 163-175
Rajananda Saraswati, Thomas W. Vetter and Robert L. Watters Jr.

Abstract: Sediment (0.3 g) was digested with 5 mL each of concentrated H2SO4 and HNO3 and 2 mL concentrated HCl in a microwave oven (program tabulated), excess HNO3 was removed and the samples were diluted to 200 mL with 2% HCl. For Hg determination, a similar method was followed using 10 mL concentrated HNO3 (program tabulated) and the digests were mixed with 0.75 mL 1% K2Cr2O7 and diluted to 100 mL with 1% H2SO4. Reduction of As and Se was performed as described previously (Analyst, 1995, 120, 95) prior to analysis by flow injection AAS at 193.7 and 196 nm, respectively (loc. cit.; operating conditions tabulated). To determine Hg, samples (500 µL) were injected into a carrier stream (10 ml/min) of 3% HCl, mixed with 1% SnCl2 (6 ml/min) in an 11 cm reaction coil and the Hg vapor was separated and carried in Ar (80 ml/min) to the absorption cell for AAS at 253.7 nm. The calibration graphs were linear for up to 20, 25 and 6 ng/ml As, Se and Hg, respectively, and the corresponding detection limits were 0.15, 0.17 and 0.15 ng/ml. The RSD are tabulated. The results agreed with those obtained using reflux column digestion; the sample preparation time was 1-2 h.
Arsenic Mercury Selenium Sample preparation Spectrophotometry Spectrophotometry Reference material Method comparison

"Determination Of Total Mercury In Environmental And Biological Samples By Flow Injection Cold Vapor Atomic Absorption Spectrometry"
Spectrochim. Acta B 1996 Volume 51, Issue 14 Pages 1867-1873
James Murphy, Phil Jones and Steve J. Hill*

Abstract: Samples (~0.25 g) are weighed into 60 mL screw-capped PTFE digestion vessels, and biological samples are treated with 5 mL of HNO3 and 1 mL of H2O2 and environmental samples with 2.5 mL of HNO3, 2.5 mL of H2SO4 and 1 mL of H2O2. The vessels are then sealed and heated in a microwave oven for 1 min at medium power. Each digestate plus 2% HNO3/2% H2SO4 washings is diluted to known volume, the solution is degassed ultrasonically, and a portion is placed in an autosampler phial. A diagram of the manifold is presented; the sample (0.5 ml) is injected into a carrier stream of 3% HCl (12 ml/min) that subsequently merges with a stream of 0.2% NaBH4 solution in 0.05% NaOH (6.7 ml/min), and the liberated Hg is carried to a quartz cell in a stream of Ar. Calibration is effected with standard solutions containing up to 30 or 60 ng/ml of Hg, and the detection limit is 0.1 ng. The results for standard dogfish tissue and estuarine sediment agreed well with the certified values. The method was applied to river sediment and canned tuna.
Mercury Spectrophotometry Sample preparation Reference material Volatile generation