Marek Trojanowicz

Porphyrins in analytical chemistry. A review

The porphyrins, naturally occurring macrocyclic compounds, have, in the last 10 years, gained increasing interest in analytical chemistry. This review based on 123 original literature references, mostly published in the 1990s, presents catalytic applications of metalloporphyrins in electroanalysis as electroactive agents in ion selective membranes, as unique reagents in spectrophotometry and as new stationary phases offering unusual resolution in HPLC. The collected data are also presented in four tables.

Functionalized Cellulose Sorbents for Preconcentration of Trace Metals in Environmental Analysis

Regardless the progress in detectability of various instrumentation for trace metal determination, the preconcentration steps are very often needed for the analysis of environmental samples. Among the different techniques that can be used for this purpose, solid-phase extraction using various sorbents has been developed very intensively in recent years. Besides preconcentration, it can also be used for matrix removal necessary in some procedures or for the speciation of trace elements. This review is based on 42 literature references and shows favorable properties of cellulose sorbents for this purpose. Depending on the functional groups attached, the sorbent can be directly used for sorption of target analytes or can be loaded with ligands specifically binding certain species. Applications are reviewed for conventional batch procedures, flow-injection sample processing, and speciation of certain trace elements.

Flow injection analysis : instrumentation and applications

The concept of flow injection analysis (FIA) was introduced in the mid-seventies. It was preceded by the success of segmented flow analysis, mainly in clinical and environmental analysis. This advance, as well as the development of continuous monitors for process control and environmental monitors, ensured the success of the FIA methodology. As an exceptionally effective means of mechanization for various procedures of wet chemical analysis, the FIA methodology, in use with a whole arsenal of detection methods of modern analytical chemistry, proved to be of great interest to many.The fast and intensive development of the FIA methodology was due to several factors essential for routine analytical determinations, such as very limited sample consumption, the short analysis time based on a transient signal measurement in a flow-through detector and an on-line carrying out difficult operations of separation, preconcentration or physicochemical conversion of analytes into detectable species.Twenty-year studies by numerous research groups all over the world have provided significant progress in the theoretical description of dispersion phenomena in FIA and various operations of physicochemical treatment of the analyte. This volume is devoted to the presentation of the current status of development of the instrumentation for FIA and the many fields of its practical applications, based on an extensive bibliography of original research publications.

INHIBITIVE DETERMINATION OF MERCURY AND OTHER METAL IONS BY POTENTIOMETRIC UREA BIOSENSOR

The biosensor with urease entrapped in PVC layer at the surface of pH-sensitive iridium oxide electrode was applied for testing of mercury and other metal ions inhibition on enzymatic reaction. The calculation of inhibition effect was based on the measurement of initial rate of decrease of biosensor potential (proportional to the initial rate of enzymatic reaction) after addition of substrate after inhibition step. Some differences of inhibition extent were observed for various mercury forms (Hg(NO3)2, HgCl2, PhHgCl and Hg2(NO3)2) as well as for other heavy metal ions investigated as potential interferents. Because the method was not specific, it was applied for the determination of total inhibition effect caused by heavy metal ions in water samples. In the case of most cations tested the total recovery of enzyme activity was possible using Tris buffer solution with EDTA and thioacetamide after less than 10 min regeneration time.

Recent developments in electrochemical flow detections--a review: part I. Flow analysis and capillary electrophoresis.

Recent years have provided numerous new examples of applying flow-through electrochemical detectors in chemical analysis. This review, based on about 250 original research papers cited from the current analytical literature, presents their application in flow analysis and capillary electrophoretic methods. Example applications are also given for arrays of electrochemical sensors in flow analysis and electrochemical detection in microfluidic systems. Potentiometric detection with ion-selective electrodes predominates in flow analysis carried out mostly in a flow-injection system, while amperometric and conductivity detections are most commonly employed in capillary electrophoresis.

Enzyme entrapped polypyrrole modified electrode for flow-injection determination of glucose

Immobilization of glucose oxidase in electropolymerized polypyrrole film on the surface of a platinum wire electrode, provides a convenient sensor for flow-injection glucose determination. An upper limit of linear response for 100 microliters injected sample volume was estimated as 20 mM, whereas a 500 microliters injected sample volume gave an estimated detection limit of 0.5 mM. A simple electrode preparation procedure allows quick electrode renewal before each series of measurements.

Investigation of natural dyes occurring in historical Coptic textiles by high-performance liquid chromatography with UV-Vis and mass spectrometric detection

Liquid chromatography (LC) combined with ultraviolet-visible (UV-Vis) and mass spectrometric (MS) detection was utilized to study the chemical components present in extracts of natural dyes originating from fiber samples obtained from Coptic textiles from Early Christian Art Collection of National Museum in Warsaw. Chromatographic retention, ionization, UV-Vis and mass spectra of twenty selected dye compounds of flavanoid-, anthraquinone- and indigo-types were studied. Most of the investigated compounds could be ionized by positive and negative ion electrospray ionization. Difficulties with the ionization by electrospray were experienced for indigotin and brominated indigotins, but these were ionized by atmospheric pressure chemical ionization. Mass spectrometric detection, utilizing different scanning modes of a triple quadrupole mass spectrometer, combined with the UV-Vis detection was demonstrated to be a powerful approach to detection and identification of dyes in the extracts of archeological textiles. Using this approach the following compounds were identified in the extracts of Coptic textiles: luteolin, apigenin, rhamnetin, kaempferol, alizarin, purpurin, xanthopurpurin, monochloroalizarin, indirubin, and so the type of dye that was utilized to dye the textiles could be identified. Detection capabilities for several dye-type analytes were compared for the UV-Vis and mass spectrometric detection. The signal-to-noise ratios obtained for luteolin, apigenin, and rhamnetin were higher for the MS detection for most of the examined sample extracts. Purpurin, alizarin, and indirubin showed similar signal-to-noise ratios for UV-Vis and mass spectrometric detection.

Determination of Pesticides Using Electrochemical Enzymatic Biosensors

In the recent decade numerous biosensing methods for detection of pesticides have been developed using integrated enzymatic biosensors and immunosensors. Enzymatic determination of pesticides is most often based on inhibition of the activity of selected enzymes such as cholinesterases, organophosphate hydrolase, alkaline and acid phosphatase, ascorbate oxidase, acetolactate synthase and aldehyde dehydrogenase. Enzymatic biosensors were developed using various electrochemical signal transducers, different methods of enzyme immobilization and various measuring methodologies. Application of single-use screen-printed biosensors in batch measurements and flow-injection analysis with enzyme biosensors are most intensively developed procedures. An improvement of detectability level can be achieved by the use of recombinant enzyme mutants, while multi-component determinations by the use of biosensor matrices and data processing with artificial neural networks. In some cases the determined pesticide can be also a substrate of enzymatic reaction. Another area of development of biosensors for determination of pesticides is in the design of microbial biosensors and photosystem-based biosensors with electrochemical biosensors.

Biosensors based on oxidases immobilized in various conducting polymers

The electrodeposited organic polymers polypyrrole, poly(N-methylpyrrole), poly(o-phenylenediamine) and polyaniline are compared as matrices for the immobilization of glucose oxidase in the preparation of amperometric glucose biosensors. Enzyme entrapment in the polymer layer is obtained by electrodeposition of polymers from solutions of monomers containing dissolved enzyme. For all examined sensors a useful and almost linear range of response to glucose is observed up to at least 20 mM of glucose. The best sensitivity of response is obtained for a glucose sensor made of poly(o-phenylenediamine) and polypyrrole. A linear response up to 20 mM glucose is also obtained in flow-injection measurements for a glucose/polypyrrole sensor. Poly(o-phenylenediamine) is also used for satisfactory immobilization of choline oxidase in the preparation of a choline sensor, whereas a lactate biosensor has been prepared by immobilization of lactate oxidase in polypyrrole.

Limitation of linear response in flow-injection systems with ion-selective electrodes

Abstract The lower limit of linear response in flow-injection systems employing membrane and second-kind ion-selective electrodes as detectors depends on the dispersion in the system and is usually much worse than in batch measurements. Below a certain value of the peak height, linearity of the electrode response is not maintained. The limiting value depends on the process causing the loss of linear response (solubility of the electrode material, contamination, or adsorption at the electrode surface), and varies from 15 to 70 mV. Chloride- iodide-, fluoride- and copper(II)-selective electrodes are discussed.