A simple, sensitive and selective cloud point extraction procedure is described for the preconcentration and atomic absorption spectrometric determination of Zn2+ and Cd2+ ions in water and biological samples, after complexation with 3,3',3",3'"-tetraindolyl (terephthaloyl) dimethane (TTDM) in basic medium, using Triton X-114 as nonionic surfactant. Detection limits of 3.0 and 2.0 µg L-1 and quantification limits 10.0 and 7.0 µg L-1were obtained for Zn2+ and Cd2+ ions, respectively. Relative standard deviation was 2.9 and 3.3, and enrichment factors 23.9 and 25.6, for Zn2+ and Cd2+ ions, respectively. The method enabled determination of low levels of Zn2+ and Cd2+ ions in urine, blood serum and water samples.

A very simple cloud point extraction (CPE) methodology for the preconcentration of trace amounts of silver and magnesium as a prior step for their determination by flame atomic absorption spectrometry (FAAS) has been developed. The method is based on the extraction of silver and magnesium at pH 10 by using non-ionic surfactant Triton X-114 and 4 methyl-3-((1-H-Indol-3-iyl) (phenyl) methyl)) -1-H-Indol (MPBIM) as a complexing agent. Several important variables that affect the CPE efficiency and FAAS signal were investigated and optimized. The calibration curves, using the preconcentration system, were linear in the range of 0.007-0.200 μg mL-1 with a correlation coefficient of 0.999. The lower limits of detection (3s) obtained in the optimal conditions were 1.47 ng mL-1 and 3.00 ng mL-1 for Mg²+ and Ag+ ions, respectively. The relative standard deviation for five replicate determinations of magnesium and silver at 0.133 μg mL-1 concentration level, were 1.17 and 0.97, respectively. The proposed method was successfully applied to the ultra-trace determination of silver and magnesium in various water samples, blood serum, urine, and radiology film samples.

A stable organic tribromide, [H2-cryptand 222]2+(Br3-)2 was utilized as an active catalyst for the trimethylsilylation/ tetrahydropyranylation of alcohols. The method is general for the preparation of OH-protected aliphatic (acyclic and cyclic), aromatic, primary, secondary and tertiary alcohols.