Search

A comparison of two separation columns for high-capacity anion chromatography is presented. The distinctive feature of both packing materials is the structure of the alkyl-chain (spacer-group) between the polymer-backbone and the functional group. All other parameters, e.g. exchange capacity, functionality and length of the spacer-arm, are identical. The retention behavior of the so-called standard-anions is investigated on both columns under identical chromatographic conditions using an experimental design technique in the course of which the composition of the elution system applied is varied. The statistical treatment of the retention data offers the possibility to explain the different chromatographic behavior of both stationary phases, at least qualitatively.

The dependence of the degree of disintegration and therefore the applicability of ion chromatography for the speciation of aluminium fluoride species was examined for two different column geometries, a standard bore and a microbore column. Besides mathematical calculations, the temperature of the separation column was varied between -5 and 50 degrees C for the observation of a temperature-dependent decomposition of the species. All species were detected by UV photometry after post-column reaction with Tiron. The results showed that the disintegration of the higher coordinated Al fluoride species (AlFn with n2) could be dramatically reduced utilizing the microbore technique. In contrast to the standard bore technique the column temperature is of minor importance. The agreement between speciation data experimentally determined by microbore chromatography and those calculated using stability constants is quite good. The standard bore technique showed bigger differences between calculated and experimentally determined species distributions.

On-line coupling of ion chromatography and atomic spectrometry (IC-ICP-(AES, MS)) are compared to so-called reference methods and other competing methods for ultra trace characterization of solid microelectronic materials. The comparison is based on analytical data gained for well characterized samples by a number of different laboratories. The matrices used for comparison are Mo, Mo-oxide, MoSix, W, W-oxide, WSix, metallic As, red P and Re. The analyte elements accessible by IC-ICP-(AES, MS) and with reference values for at least one other method are Ag, Al, Ba, Ca, Cd, Cr, Co, Cu, Fe, K, Mg, Mn, Na, Ni, Ti, Tl, Th, U and Zn. The agreement of results of IC-ICP-(AES, MS) with those of isotope dilution mass spectrometry (IDMS) and radiochemical activation analyses (RNAA) shows good accuracy for most elements and some contamination problems with ubiquitous elements. A correlation of IC-ICP-(AES, MS) and GDMS results is undoubtful, but the discrepancies are rather high. As further technique ETV-ICP-MS is compared, whose results are in reasonable agreement with IC-ICP-(AES, MS). Details on some new applications as well as of some new methodological enhancements of on-line coupling IC-ICP(AES, MS) for the matrices As and P were included.

Low- and intermediate-level waste is frequently supercompacted or solidified in cement for final disposal. In waste characterisation matrix problems arise in analysing the drum content by chromatographic methods. The cations from the cement occupy the capacity of the column and no separation of the analytes takes place. By a selective complexation the analytes get separated from the matrix. The analytes Pb, Ni, Co and Se are bound by sodiumdiethyldithiocarbamate (NaDDTC) as complexes on a precolumn and subsequently separated on a reversed-phase column. Detection is performed by a UV/VIS spectral range detector and a liquid scintillation detector (Pb-210, Ni-63, Co-60) in series.

The on-line-coupling of ion chromatography (IC) and inductively coupled plasma mass spectrometry (ICP-MS) is a powerful tool for the determination of bromate in drinking waters. The use of a high-capacity and high-performance anion-exchanger combined with an NH4NO3-based elution system allows the determination of bromate in almost every water sample without any sample pretreatment. The method detection limits in the water samples investigated are 50 to 65 ng/L or 44 to 58 pg bromate, respectively. Considering sensivity as well as imprecision (5% at 500 ng/L bromate) and short analysis times (8 to 15 min per sample including sample uptake), the described IC-ICP-MS coupling is well suited for precise routine analyses of bromate in drinking waters at the sub μg/L level.

The current state of on-line coupling between liquid chromatography and inductively coupled plasma mass spectrometry is reviewed. The applications can be divided into three subgroups by changing the importance of the coupling partners. An overview is given of applications in these subgroups, of its use as preconcentration and matrix elimination techniques, for the elimination of spectral interferences and as a tool for speciation analysis. A discussion of current and future development areas in on-line HPLC-ICP-MS is also included.

This work presents the benefits of coupling techniques such as Electro Thermal Vaporisation (ETV)-ICP-MS and Ion Chromatography (IC)-ICP-(AES, MS) for ultra trace analysis in a high purity rhenium powder sample. Direct analysis using ICP-AES suffers from poor detection limits and allows trace analysis only above 1 μg/g for most analytes. ICP-MS analysis of trace elements is more sensitive, but signal depression caused by the heavy Re-ions limits trace analysis to concentrations of 50–100 ng/g analyte in the solid sample. Coupling Ion Chromatography with ICP-spectrometers, combined with time resolved measurement (IC-ICP-TRM) of the elution signals, was used to enhance the sensitivity of both ICP-AES and ICP-MS. Resulting detection limits are in the very low ng/g to pg/g range. Coupling of ETV and ICP-MS offers the possibility of eliminating the volatile Re2O7 matrix by thermal pretreatment and allows ICP-MS measurements without matrix interferences caused by Re. Results from these methods are compared with Glow Discharge Mass Spectrometry (GDMS) analysis, a semiquantitative solid state technique. The results are also compared with the manufacturers' specifications to show the power of modern routine analysis using ICP-AES or FAAS.

On-line coupling of Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES) and Ion Chromatography (IC) offers unique features for ultra trace analysis. With an on-line preconcentration procedure based on cation exchange, sub-ng/g analysis is possible in complex matrices like molybdenum and tungsten. Results match with isotope dilution mass spectrometry (IDMS) and are comparable with glow discharge mass spectrometry (GDMS). The optimal dissolution reagent for these matrices is hydrogen peroxide whose clean up to ultra high purity is possible with metal-free chromatographic equipment. All elements with cationic chemistry can be preconcentrated in acidic peroxide solutions. In this study 21 elements are measured which are detrimental for microelectronic applications. The absolute detection limits of the IC-ICP combination, with time resolved registration, are at the lower ng-level. The reproducibility is not significantly lowered by the coupling, but a ten-fold sensitivity enhancement is observed in comparison to chemically similar off-line trace-matrix-separations. Other features are simultaneous matrix corrections, use of monitors lines for method enhancement, error recognition and correction using time resolved measurement and simple calibration of the method with aqueous standards.

Bromate and nitrite are formed during the disinfection of water. The German threshold value for nitrite in drinking water is 100 μg/L, for bromate a limit below 50 μg/L has to be established. A self-made high-capacity resin with 2-(dimethylamino)-ethanol functionality in combination with a UV-transparent elution system based on perchloric acid allows the separation and sensitive photometric detection of nitrite and bromate, even if high chloride concentrations are present. The high capacity of the strongly basic resin allows sample volumes of up to 400 μL without disturbance of the separation. Detection limits for bromate and nitrite are 15 and 10 μg/L, respectively. The direct analysis of water samples with high salt contents, such as disinfected pool water, is possible by insertion of an on-line chloride removal step.

An established method for the determination of the disinfection by-product bromate is ion chromatography (IC). This paper presents a comparison of three IC methods based on either conductivity detection (IC-CD), a post-column-reaction (IC-PCR-VIS) or the on-line-coupling with inductively coupled plasma mass spectrometry (IC-ICP-MS). Main characteristics of the methods such as method detection limits (MDL), time of analysis and sample pretreatment are compared and applicability for routine analysis is critically discussed. The most sensitive and rugged method is IC-ICP-MS, followed by IC-PCR-VIS. The photometric detection is subject to a minor interference in real world samples, presumably caused by carbonate. The lowest sensitivity is shown by the IC-CD method as slowest method compared, which, in addition, requires a sample pretreatment. The highest amount of information is delivered by IC-PCR-VIS, which allows the simultaneous determination of the seven standard anions and bromate.