Evaluation of a flow-through dialysis probe for sampling and sample preparation: Hyphenation to ion chromatography.

A commercially available dialysis probe has, for the first time, been evaluated for sampling and sample preparation in combination with ion chromatography (IC). In operation the probe is immersed into the sample solution and a receiver liquid is propelled through the probe behind a suitable dialysis membrane. Small inorganic anions (fluoride, chloride, nitrite, bromide, nitrate, sulfate, phosphate) are transferred across the membrane into the receiver liquid and carried towards the injection valve of the IC system.

Investigation of retention of undesirable organic matter from aqueous samples in stopped-flow dialysis procedures for inorganic anions.

Sample preparation is a key issue in the analysis of many real samples using ion chromatography (IC). One of the many means of sample preparation that has received considerable attention in recent years is the stopped-flow in-line dialysis approach hyphenated to IC. Using appropriate dialysis membranes undesirable high-molecular weight compounds, colloids and dispersed particulate matter are retained whereas the analyte ions pass through the membrane and are separated and quantified by IC.

Membrane-based sample preparation for ion chromatography-Techniques, instrumental configurations and applications.

Sample preparation is the bottleneck of many analytical methods, including ion chromatography (IC). Procedures based on the application of membranes are important, yet not well appreciated means for clean-up and analyte preconcentration of liquid samples. Filtration, ultrafiltration, the variety of dialysis techniques, i.

Tolerability and safety of Octagam® (IVIG): a post-authorization safety analysis of four non-interventional phase IV trials .

Objective: To evaluate the tolerability and safety of Octagam 5% and 10% across all indications, ages, and treatment regimens, using data from four non-interventional post-authorization safety studies (PASS); this analysis was performed following changes in the preparation of raw material used to manufacture Octagam.

Methods: All four studies included in- and out-patients prescribed Octagam for treatment of their medical condition. Physicians used case report forms to document baseline demographics, Octagam treatment details, and data on the efficacy of Octagam, and recorded all adverse drug reactions (ADRs) and other safety data.

Toxicological screening of human plasma by on-line SPE-HPLC-DAD: identification and quantification of acidic and neutral drugs.

A multi-analyte screening method for the quantification of 50 acidic/neutral drugs in human plasma based on on-line solid-phase extraction (SPE)-HPLC with photodiode array detection (DAD) was developed, validated and applied for clinical investigation. Acetone and methanol for protein precipitation, three different SPE materials (two electro-neutral, one strong anion-exchange, one weak cation-exchange) for on-line extraction, five HPLC-columns [one C18 (GeminiNX), two phenyl-hexyl (Gemini C6 -Phenyl, Kinetex Phenyl-Hexyl) and two pentafluorophenyl (LunaPFP(2), KinetexPFP)] for analytical separation were tested. For sample pre-treatment, acetone in the ratio 1:2 (plasma:acetone) showed a better baseline and fewer matrix peaks in the chromatogram than methanol.

Toxicological screening of human plasma by on-line SPE-HPLC-DAD: identification and quantification of basic drugs and metabolites.

An automated multi-analyte screening method for the identification and quantification of 92 drugs and metabolites based on on-line solid-phase extraction-high-performance liquid chromatography-diode array detection technique was developed and successfully validated. In addition, a database with 870 entries including UV-spectra, relative/retention times and response factors of toxicologically relevant compounds was created. Plasma samples (0.

A critical examination of sorbent extraction pre-concentration with spectrophotometric sensing in flowing systems.

In this paper, the solid-phase spectrophotometric concept is critically examined in flow systems exploiting a dedicated microcolumn-based optical sensor packed with octadecyl chemically-modified silica gel. The flow configuration integrates matrix separation with pre-concentration and on-column sensing of non-polar complexes resulting from analyte derivatization. The design criteria for optimum performance of both the sorbent-packed microcolumn and optosensing instrumentation are for the first time discussed in detail.

Characterisation of a gas-diffusion membrane-based optical flow-through sensor exemplified by the determination of nitrite.

A membrane-based optical flow-through sensor is described which can be alternatively used for absorbance and reflectance detection within the receiver channel of a sandwich-type gas-diffusion separation cell. Using the common spectrophotometric detection scheme for nitrite based on azo-dye formation, the principle features of the flow-through sensor are investigated and the performance is characterised particularly with regard to selectivity and sensitivity aspects. The determination of nitrite in waste waters and meat extracts was used to demonstrate the applicability to real sample analysis.

A novel dynamic approach for automatic microsampling and continuous monitoring of metal ion release from soils exploiting a dedicated flow-through microdialyser.

In this paper, a novel concept is presented for automatic microsampling and continuous monitoring of metal ions in soils with minimum disturbance of the sampling site. It involves a hollow-fiber microdialyser that is implanted in the soil body as a miniaturized sensing device. The idea behind microdialysis in this application is to mimic the function of a passive sampler to predict the actual, rather than potential, mobility and bioavailability of metal traces.

Microanalytical flow-through method for assessment of the bioavailability of toxic metals in environmental samples.

The application of a recently proposed microanalytical flow-through system for on-line sequential extraction of heavy metals from solid samples of environmental interest is described. Using various extraction schemes (a nitric acid scheme, a two-stage extraction scheme using two reagents applied in the BCR procedure) and comparison with the common batch sequential BCR procedure, the suitability of the system for fast screening of solid environmental samples is demonstrated. By pumping leaching agents sequentially through the sample held in a micro cartridge, the different metal fractions present can be assessed in less than an hour.

Implantable flow-through capillary-type microdialyzers for continuous in situ monitoring of environmentally relevant parameters.

In this paper, a simple, flexible, and cost-effective flow-through microdialyzer hyphenated with a miniaturized differential potentiometric detector is proposed for continuous diffusion-controlled sampling of analytes of environmental interest. The analytical performance of the dedicated configuration involving merely a single cellulose regenerated hollow fiber is critically compared with that of commercially available concentric probes commonly exploited for in vivo monitoring of the extracellular space in living tissues and that of large dialysis-based probes furnished with flat membranes. The outstanding feature of the capillary-type design is the ability of adapting the extraction fractions (EF) to the requirements of the assays and flow-through detectors by selection of appropriate membrane length/perfusion rate ratios.

Development of a hyphenated microanalytical system for the investigation of leaching kinetics of heavy metals in environmental samples.

A fast and convenient method for on-line monitoring of the extraction of heavy metals from solid (environmental) matrixes was developed. By the incorporation of microcartridges filled with dried and pulverized solid samples into the conduits of a flow system and appropriate selection of the liquid flowing through the cartridge, information about the degree of leaching and in particular of the kinetics of the leaching process are obtained. The method was optimized for determination of different metals of environmental concern using in-line detection by FAAS and ICPMS.

A novel flow-through microdialysis separation unit with integrated differential potentiometric detection for the determination of chloride in soil samples.

In this paper, a novel and miniaturised flow-through dialysis-based potentiometric detector is proposed for the determination of chloride in soil samples. The outstanding feature of the designed unit is the integration of analyte isolation from matrix constituents via membrane separation with differential potentiometric detection. Two identical tubular all-solid-state Ag/AgCl ion selective electrodes (ISEs) were assembled respectively at the inlet and outlet of the acceptor channel.