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
Website: @unf

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Classification: Plant -> citrus -> leaves

Citations 2

"Comparison Of Plumbane And Tetraethyllead For The Determination Of Lead By Inductively Coupled Plasma Atomic-emission Spectrometry"
Anal. Chim. Acta 1995 Volume 309, Issue 1-3 Pages 369-378
M. C. Valdés-Hevia y Temprano, M. R. Fernández de la Campa and A. Sanz-Medel*

Abstract: Sediments and lichen (200 mg) were microwave digested in 1.5 mL concentrated HNO3, 0.5 mL 80% HClO4 and 0.5 mL concentrated HF (details given). After cooling, the excess HF was reacted with 3.5 mL 6% H3BO3, the mixture re-digested and the contents made to 100 mL with water. Citrus leaves and lyophilized vegetables (0.5 g) were digested in 5 mL 65% HNO3 and 2 mL H2O2 and the contents made to 25 mL with water. The solutions were mixed to contain 0.3% or 0.7% K2Cr2O7 for PbH4 (I) or tetraethyllead (II) analysis and merged at 1 ml/min with carrier streams (1 ml/min) of 360 mM or 600 mM lactic acid for I and II, respectively, and 5% NaBH4 in 0.1% NaOH for I or 1% sodium tetraethylboron in 1% NaOH for II. The mixed solutions were aspirated at 2.4-3 ml/min into a detuned grid-nebulizer for ICP-AES and Pb determined at 0.7 kW and 20.353 nm. Calibration graphs were linear up to 0.5 mg/ml of I and 1.5 mg/ml of Pb for II with detection limits of 2 ng/ml and 1 ng/ml of Pb, respectively. At 50 ng/ml of Pb the RSD (n = 10) were 1.3% for I and 1.2% for II. The selectivity of the two methods in the presence of chloride, nitrate and a range of cations was confirmed. The analysis of Pb via II was preferred as only Ni and Sb interfered.
Lead Sample preparation Spectrophotometry Interferences Volatile generation Optimization Volatile generation

"Liquid-liquid Extraction In Flow Injection Analysis Using An Open-phase Separator For The Spectrophotometric Determination Of Copper In Plant Digests"
Analyst 1998 Volume 123, Issue 2 Pages 191-193
Telma Blanco, Nelson Maniasso, Maria Fernanda Giné and Antonio O. Jacintho

Abstract: A flow injection system with an open-phase separation device is presented for the liquid-liquid extraction of the diethyldithiocarbamate-copper complex (DDTC-Cu) using carbon tetrachloride (CCl4). An open tube enclosed by computer-controlled solenoid valves was installed vertically to promote fast phase separation by differences in density. The solenoid valves were used to introduce the reacted sample zone into the tube, to select a precise volume of the extracted complex to be detected and to pass the remaining solution to waste. A pre-concentration factor of 10 was attained, corresponding to the aqueous to organic phase volume ratio. The solenoid valve control allowed the use of a small solvent volume (0.7 mL) per determination The DDTC-Cu complex was detected at 436 nm. A sample throughput of 30 determinations per h for Cu ranging from 50 to 400 µg/L in real samples was achieved. A limit of detection of 5 µg/L of Cu was calculated using 3sv. A precision characterized by an RSD of less than 3 was typical for a sample with a Cu concentration of 145 µg/L. The accuracy was assessed with NIST SRM 1572 and no difference at the 95 confidence level was found.
Copper Sample preparation Spectrophotometry Reference material Solvent extraction Phase separator Computer