Archava Siriraks

Ion chromatography of heavy and transition metals by on- and post-column derivatizations

A new method for the simultaneous separation and determination of mercury(II) with other heavy and transition metals by ion chromatography (IC) was developed. This method involves on-column derivatization with 2,6-pyridinedicarboxylic acid (PDCA) and anion-exchange separation, followed by a post-column reaction with 2-[(5-bromo-2-pyridyl)-azo]-5-diethylaminophenol (5-Br-PADAP) to form metal-5-Br-PADAP chelates, which can be sensitively monitored by spectrophotometric detection at 565 nm. PDCA was first combined with Na2C2O4 to separate the metals within 16 min. The optimum separation and derivatization conditions were studied in detail. The detection limits of Pb2+, CU2+, Ni2+ Zn2+, Co2+, Cd2+, Mn2+ and Hg2+ were 0.2 mgl(-1) (115 mu l loop), 1.5, 5, 0.5, 5, 5, 3 and 20 mu gl(-1) (676 mu l loop), respectively. This method was applied to the analysis of standard rice sample, waste cellpacking and municipal solid waste fly ash with satisfying results

High-performance ion chromatographic separation of uranium and thorium in natural waters and geological materials

Abstract An ion chromatographic separation of uranium and thorium is described. The method uses a cation-exchange resin for the separation of uranium and thorium from other common metal interferences. Detection of uranium and thorium is accomplished using post-column derivatization with arsenazo III followed by spectrophotometric detection. In addition to direct injection of sample, a method for concentrating uranium and thorium from complex matrices will be presented. Using direct injection, detection limits for uranium and thorium in simple matrices is 20 μg/l for uranium and 60 μg/l for thorium using a 50-μl sample loop. The use of a chelating resin for selective sample concentration lowers the detection limit to 1.0 μg/l for uranium and 3.0 μg/l for thorium when concentrating 5.0 ml of sample. Sample concentration on a selective chelating resin also extends the applicability of the method for the analysis of complex matrices.

Determination of trace anions in concentrated acids by means of a moderate-capacity anion-exchange column

Abstract The development of a moderate-capacity anion-exchange resin has resulted in new ion chromatography (IC) methods for the determination of trace anions is concentrated acids. Suppressed microbore IC offers a higher suppression capability, which allows higher-capacity analytical columns to be used. As a result, higher-capacity columns permit higher concentrations of acids to be injected into the column without overloading, thus improving trace anion detection limits. In addition, using a selective matrix elimination method, high concentrations (% levels) of weak acids ( e.g. hydrofluoric acid and acetic acids) may be eliminated prior to analysis by IC.

Improved method for the determination of manganese in nuclear power plant waters

Abstract An improved method for manganese determination in nuclear power plant waters has been developed. This method combines a selective chelation concentration method with a unique analytical separation for manganese from the interfering matrix using a weak acid cation exchange column. The detection sensitivity by conventional post-column derivatization is improved with the combination of chemical eluent suppression and subsequent post-column derivatization. The detection limit for manganese in ammonium matrix is approximately 2 pg/ml and the limit of quantitation 10 pg/ml with 100 ml sample volume.