bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of the quantitativeness of matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry using an equimolar mixture of uniform poly(ethylene glycol) oligomers
Authors: Shimada Kayori , Nagahata Ritsuko , Kawabata Shin‐ichiro , Matsuyama Shigetomo , Saito Takeshi , Kinugasa Shinichi
Published: September 2003

Quantitativeness of matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOFMS) was elucidated using an equimolar mixture of uniform poly(ethylene glycol) (PEG) oligomers with no molecular weight distributions. Uniform PEG oligomers with degrees of polymerization n = 6–40 were separated from commercial PEG samples by preparative super‐critical fluid chromatography. MALDI‐TOF mass spectra of an equimolar mixture of the uniform PEG oligomers were recorded by adding a mixture of 2,5‐dihydroxybenzoic acid as a matrix reagent and four chlorinated salts, i.e. LiCl, NaCl, KCl and RbCl. Remarkable non‐quantitative effects were observed in the MALDI‐TOF mass spectra in both the lower and higher molecular mass regions. At higher molecular masses greater than about 103, PEG oligomers with larger molecular mass yielded lower spectral intensities irrespective of the species of adduct cations and higher laser powers induced larger decreases in mass spectral intensities with the increase in their molecular masses. On the other hand, in the lower molecular mass region, less than about 103, the observed non‐quantitative effect greatly depends on the species of adduct cations, indicating that the stability of the PEG–cation complex affects the MALDI‐TOF mass spectral intensities of uniform PEG oligomers. Copyright © 2003 John Wiley & Sons, Ltd.
Post‐translational modification of Rhodococcus R312 and Comamonas NI1 nitrile hydratases
Authors: Stevens Julie M. , Belghazi Maya , Jaouen Maryse , Bonnet Didier , Schmitter Jean‐Marie , Mansuy Daniel , Sari Marie‐Agnès , Artaud Isabelle
Published: September 2003

Nitrile hydratases (NHases) are industrially significant iron‐ and cobalt‐containing enzymes used in the large‐scale synthesis of acrylamide. Previous reports have shown that the active site peptides of NHases are post‐translationally modified by oxidation of cysteine residues, and that these modifications are essential for catalysis. We report mass spectrometric evidence of the oxidation states of the active site cysteines in the iron coordination spheres of two iron‐containing nitrile hydratases, namely R312 NHase from Rhodococcus rhodochrous strain R312 and NI1 NHase from Comamonas testosteroni. At least one of these cysteines is oxidised to a sulfinic acid (SO2H) and there is also evidence suggesting an additional oxidation to a sulfenic acid (SOH). This is the first evidence for the presence of these oxidation states for full‐length NHases and for Fe‐NHases from different microorganisms. The presence of these covalent modifications was confirmed by performing mass spectrometry on the active site peptide of R312 NHase, under native, reduced and carboxymethylated conditions. We also show the nitrosylation of the iron by mass spectrometry, as well as the release of NO by photoirradiation. Copyright © 2003 John Wiley & Sons, Ltd.
Characterization of aconitine‐type alkaloids in the flowers of Aconitum kusnezoffii by electrospray ionization tandem mass spectrometry
Authors: Wang Yong , Song Fengrui , Xu Qingxuan , Liu Zhiqiang , Liu Shuying
Published: September 2003

The fragmentation mechanism of aconitine‐type alkaloids in the flowers of Aconitum kusnezoffii (FAK) was investigated using electrospray ionization tandem mass spectrometry (ESI‐MSn) firstly. The analysis of the collision‐induced dissociation (CID) spectra of three purified aconitine standards and six previously reported aconitines indicated that the fragmentation of the protonated aconitines at low‐energy CID follows a similar pathway. The elimination of a C8‐substituent such as an acetic acid or a fatty acid is the dominant fragmentation mode in MS2. Successive losses of CH3COOH, CH3OH, H2O, BzOH, and CO are the main fragmentation pathways of aconitine‐type alkaloids in MS3 spectra. Based on these features, a rapid method for the direct detection and characterization of alkaloids from an ethanolic extract of FAK is described. All the known aconitum alkaloids are detected and a series of lipo‐aconitines has been found for the first time in this plant. Copyright © 2003 John Wiley & Sons, Ltd.
Gas‐phase investigation of Pd(II)‐alanine complexes with small native and derivatized peptides containing histidine
Authors: Anbalagan V. , Van Stipdonk M. J.
Published: September 2003

We report here the generation of gas‐phase complexes containing Pd(II), a ligand (deprotonated alanine, A−), and/or N‐terminus derivatized peptides containing histidine as one of the amino acids. The species were produced by electrospray ionization, and their gas‐phase reactions were investigated using ion‐trap tandem mass spectrometry. Pd(II) forms a stable diaqua complex in the gas phase of the formula, [Pd(A−) (H2O)2]+, (where A− = deprotonated alanine) along with ternary complexes containing A− and peptide. The collision‐induced dissociation (CID) patterns of the binary and ternary complexes were investigated, and the dissociation patterns for the ternary complexes suggest that: (a) the imidazole ring of the histidine side group may be the intrinsic binding site of the metal ion, and (b) the peptides fragment primarily by cleavage of the amide bond to the C‐terminal side of the histidine residues. These observations are in accord with previous solution‐state studies in which Pd(II) was shown to cause hydrolysis of an amide bond of a peptide at the same position. Copyright © 2003 John Wiley & Sons, Ltd.
New designer drug 1‐(3‐trifluoromethylphenyl) piperazine (TFMPP): gas chromatography/mass spectrometry and liquid chromatography/mass spectrometry studies on its phase I and II metabolism and on its toxicological detection in rat urine
Authors: Staack Roland F. , Fritschi Gieselher , Maurer Hans H.
Published: September 2003

Studies are described on the phase I and II metabolism and the toxicological analysis of the piperazine‐derived designer drug 1‐(3‐trifluoromethylphenyl)piperazine (TFMPP) in rat urine using gas chromatography/mass spectrometry (GC/MS) and liquid chromatography/mass spectrometry (LC/MS). The identified metabolites indicated that TFMPP was extensively metabolized, mainly by hydroxylation of the aromatic ring and by degradation of the piperazine moiety to N‐(3‐trifluoromethylphenyl)ethylenediamine, N‐(hydroxy‐3‐trifluoromethylphenyl)ethylenediamine, 3‐trifluoromethylaniline, and hydroxy‐3‐trifluoromethylaniline. Phase II reactions included glucuronidation, sulfatation and acetylation of phase I metabolites. The authors' systematic toxicological analysis (STA) procedure using full‐scan GC/MS after acid hydrolysis, liquid‐liquid extraction and microwave‐assisted acetylation allowed the detection of TFMPP and its above‐mentioned metabolites in rat urine after single administration of a dose calculated from the doses commonly taken by drug users. Assuming similar metabolism, the described STA procedure should be suitable for proof of an intake of TFMPP in human urine. Copyright © 2003 John Wiley & Sons, Ltd.
Atmospheric pressure chemical ionization mass spectrometry and in‐source fragmentation of lutein esters
Authors: Tian Qingguo , Duncan Christine J. G. , Schwartz Steven J.
Published: September 2003

Negative‐ion atmospheric pressure chemical ionization (APCI) mass spectrometry and in‐source collisionally induced dissociation (CID) were employed to obtain structural information of lutein esters from marigold extract. Both molecular ions and structurally significant fragments corresponding to the loss of fatty acids were observed in high abundance in the current study. Six lutein diesters including lauroylmyristoyl‐lutein (LML), dimyristoyl‐lutein (dML), myristoylpalmitoyl‐lutein (MPL), dipalmitoyl‐lutein (dPL), palmitoylstearoyl‐lutein (PSL) and distearoyl‐lutein (dSL) were characterized in a marigold flower extract. Breakdown curves (plots of relative ion abundance vs. internal energy) of three lutein diesters were established by monitoring the relative ion abundance of molecular and fragment ions at different cone voltages during negative‐ion APCI‐LC/MS analysis. Copyright © 2003 John Wiley & Sons, Ltd.
Acrolein‐sequestering ability of endogenous dipeptides: characterization of carnosine and homocarnosine/acrolein adducts by electrospray ionization tandem mass spectrometry
Authors: Carini Marina , Aldini Giancarlo , Beretta Giangiacomo , Arlandini Emanuele , Facino Roberto Maffei
Published: September 2003

Acrolein (ACR), the carbonyl toxin produced by lipid peroxidation, is significantly increased in Alzheimer's disease brain. Since ACR is one of the most reactive and neurotoxic aldehydes, and human brain contains both carnosine (β‐alanine‐L‐histidine) and homocarnosine (γ‐aminobutyryl‐L‐histidine), the aim of this work was first to evaluate the quenching ability of the two peptides towards ACR and then to characterize their reaction products by electrospray ionization tandem mass spectrometry (ESI‐MS/MS; infusion experiments; positive‐ion mode). The reaction progress of ACR with carnosine or homocarnosine was studied in phosphate buffer, by monitoring ACR consumption (by reverse‐phase LC) and formation of the reaction products by ESI‐MS/MS at different incubation times. N‐Acetylcarnosine was used as reference compound to identify the sites of reaction. Both the dipeptides were able to quench ACR by almost 60% at 1 h and by more than 85% after 3 h incubation. Different reaction products between ACR and carnosine/homocarnosine were detected after 3 and 24 h, to indicate a complex reaction pathway involving sequential addition of 1, 2 and 3 moles of ACR/mole of the dipeptide to both the β‐alanine and histidine residues. The ESI mass spectra of ACR/carnosine reaction mixtures indicate formation of several molecular species, among which the predominant are: (a) the 14‐membered macrocyclic derivatives, deriving from the formation of the iminic bond between the terminal amino group followed by intramolecular Michael addition of the C(3) of the ACR moiety to histidine; (b) the Nβ‐(3‐formyl‐3,4‐dehydropiperidino) derivatives arising from the Michael addition of two acrolein molecules to the amino group of β‐alanine, followed by an aldol condensation and dehydration.

The reaction of homocarnosine with ACR follows the same pathway, giving rise to the formation of homologous adducts. The results of this study shed light on the mechanism, until now never demonstrated, through which carnosine and homocarnosine detoxify the highly reactive aldehyde acrolein in a buffer system, and represent the starting point for further studies aimed at elucidating the biological role of these dipeptides in brain. Copyright © 2003 John Wiley & Sons, Ltd.
Determination of estrogens and progestogens by mass spectrometric techniques (GC/MS, LC/MS and LC/MS/MS)
Authors: Díaz‐Cruz M. Silvia , López de Alda María J. , López Ramón , Barceló Damià
Published: September 2003

Steroid sex hormones and related synthetic compounds have been shown to provoke alarming estrogenic effects in aquatic organisms, such as feminization, at very low concentrations (ng/L or pg/L). In this work, different chromatographic techniques, namely, gas chromatography/mass spectrometry (GC/MS), liquid chromatography/mass spectrometry (LC/MS) and liquid chromatography/tandem mass spectrometry (LC/MS/MS), are discussed for the analysis of estrogens, both free and conjugated, and progestogens, and the sensitivities achieved with the various techniques are inter‐compared. GC/MS analyses are usually carried out after derivatization of the analytes with bis(trimethylsilyl)trifluoroacetamide (BSTFA). For LC/MS and LC/MS/MS analyses, different instruments, ionization techniques (electrospray (ESI) and atmospheric pressure chemical ionization (APCI)), ionization modes (negative ion (NI) and positive ion (PI)) and monitoring modes (selected ion monitoring (SIM) and selected reaction monitoring (SRM)) are generally employed. Based on sensitivity and selectivity, LC/ESI‐MS/MS is generally the method of choice for determination of estrogens in the NI mode and of progestogens in the PI mode (instrumental detection limits (IDLs) 0.1–10 ng/mL). IDLs achieved by LC/ESI‐MS in the SIM mode and by LC/ESI‐MS/MS in the SRM mode were, in general, comparable, although the selectivity of the latter is significantly higher and essential to avoid false positive determinations in the analysis of real samples. Conclusions and future perspectives are outlined. Copyright © 2003 John Wiley & Sons, Ltd.
Quantitative determination of UV filters in sunscreen lotions using microemulsion electrokinetic chromatography
Authors: Klampfl Christian W. , Leitner Tanja
Published: September 2003

Microemulsion electrokinetic chromatography (MEEKC) has been applied to the separation of some UV filters (Eusolex 4360, Eusolex 6300, Eusolex OCR, Eusolex 2292, Eusolex 6007, Eusolex 9020, Eusolex HMS, Eusolex OS, and Eusolex 232) commonly used in sunscreen lotions. Use of a MEEKC buffer with a mixed surfactant system to stabilize the oil droplets and an organic modifier in the aqueous phase allowed separation of most of the selected analytes in a single run in a system fitted with a diode array detector recording three wavelengths (240 nm, 300 nm, and 380 nm) simultaneously. The microemulsion employed consisted of 2.25 g of SDS, 0.75 g of Brij 35, 6.6 g 1‐butanol, 0.8 g n‐octane, 17.5 g 2‐propanol, and 72.1 g of 10 mM borate buffer (pH 9.2). Detection limits from 0.65 to 6.0 μg/mL were obtained and the calibration plots were linear over at least one order of magnitude for all analytes. The developed method could be applied to the determination of UV filters in several sun protection products including lotions, milks, and oils. Comparison of the obtained data with those from an HPLC method described in the literature showed acceptable agreement.
GC analysis of extractive compounds in beech wood
Authors: Zule Janja , Može Adolf
Published: September 2003

Various highly hydrophobic beech wood lipids were characterized and their quantities measured in hexane extracts by GC, using short and long capillary columns. More polar compounds were also identified in acetone extracts. Triglycerides, steryl esters, sterols, unsaturated fatty acids, as well as various monosaccharide units were determined as possible pollutants of papermaking systems.
Characterisation of interferon α‐2b by liquid chromatography and mass spectrometry techniques
Authors: Cindrić Mario , Vuletić Marko
Published: September 2003

Interferon α‐2b produced by Escherichia coli consists of 165 amino acids and contains two disulphide bonds; its purity was confirmed by LC‐UV (DAD)‐FLD and LC‐MS techniques. A C4 column was used with UV detection at 214 nm; diode array detector (DAD) spectra were recorded from 200–400 nm and fluorescence detection was performed at specific wavelengths of trypthophan emission and excitation. Peptide mapping was performed with trypsin. Peptides produced by trypsin digestion were analysed by LC‐UV (DAD)‐FLD, LC‐MS, and LC‐MS/MS using a C18 column. Amino acid sequence coverage was about 95%. UV spectra in the range from 200 nm to 400 nm, emission (Em) and excitation (Ex) spectra of each separated peptide were additionally compared with spectra of the same peptide produced by digestion of European Pharmacopaeia interferon α‐2b standard (spectral matching). The chromatogram of any interferon α‐2b (drug substance or certificated standard) sample produced in the same manner with the same amino acid composition should be similar to the chromatogram obtained by the method described in this paper. Molecular masses of peptides were obtained from MS experiments and MS/MS experiments gave additional structural information. The molecular mass of interferon α‐2b was obtained by MALDI‐TOF MS analysis in linear mode, with an accuracy comparable to the theoretical average mass ± 5 atomic mass units. The molecular mass was obtained from the deconvoluted ESI mass spectrum.
Comparison of gas and high performance liquid chromatography with selective detection for determination of triazine herbicides and their degradation products extracted ultrasonically from soil
Authors: Stipičević Sanja , Fingler Sanja , Zupančič‐Kralj Lucija , Drevenkar Vlasta
Published: September 2003

GC and HPLC with selective detectors were compared for simultaneous determination of triazine herbicides simazine, atrazine, propazine, terbuthylazine, cyanazine, ametryn, prometryn, and atraton, and of their dealkylated degradation products in soil. The compounds were ultrasonically extracted from spiked agricultural soil samples (organic matter content < 5%) with a 2:1 acetone:n‐hexane mixture. High efficiency of GC capillary column and high selectivity of the thermionic sensitive detector (TSD) and ion trap detector (ITD) made it possible to directly analyse uncleaned soil extracts and determine all 12 compounds in one run. In reversed‐phase HPLC with diode‐array detector (DAD), the co‐elution of soil matrix components interfered with the determination of methylthiotriazines and terbuthylazine. The recovery of triazine compounds, determined by GC‐TSD, from a silty sand soil (organic matter content 1.82%, pH 6.22) spiked at levels of 15–600 ng g–1, were 70–90% (RSD 9–19%), except for deisopropylatraton (38%). GC‐TSD analysis with detection limits of 5–15 ng g–1 for chloro‐ and methylthiotriazines and 30 ng g–1 for methoxytriazines was more sensitive than GC‐MS(ITD). GC analysis with electron capture detection was sensitive for some chlorotriazines, but a reliable compound quantification in complex chromatograms of uncleaned soil of extracts was not possible. For all compounds save didealkylatrazine, HPLC‐DAD was at least two times less sensitive than GC‐TSD. Soil/sediment organic matter, clay and silt content, and pH were identified as matrix characteristics which might affect ultrasonic extraction recovery of a particular compound.
Microwave‐assisted saponification for the determination of 16 polycyclic aromatic hydrocarbons from pumpkin seed oils
Authors: Gfrerer Marion , Lankmayr Ernst
Published: September 2003

The production of pumpkin seed oil requires a roasting of the pumpkin seeds, at temperatures generally higher than 60°C. The roasting at elevated temperatures produces the typical taste of the pumpkin seed oil but may also be the source of a contamination with carcinogenic PAHs. Owing to their lipophilic character, their bioaccumulation, and their toxicity these compounds should be subject to mandatory monitoring. Since there is a lack of norms and legal limits for hot‐pressed oils, the limits set by the German Society of Fat Science of 25 μg/kg for the sum of 16 PAHs and 5 μg/kg for the heavy fraction for refined and cold‐pressed oils, such as olive oil and others, have to be applied. Sample preparation was performed by microwave‐assisted saponification with 1.5 M methanolic potassium hydroxide followed by a liquid‐liquid extraction and purification with sulfuric acid. A final clean up procedure was performed on activated silica gel combined with a preparative Bondesil‐cyano phase. For a selective measurement of the individual analytes, gas chromatography combined with mass spectroscopy was used in single ion monitoring mode. The overall analytical procedure was validated by systematic recovery experiments and by analyzing the certified reference material BCR CRM 458. Finally, this validated method was used for quality control of pumpkin seed oils from a producer co‐operative.
Separation of isomers of dienoic acids by electromigration techniques
Authors: Cigić Irena Kralj , Guček Marjan , Zupančič‐Kralj Lucija , Pihlar Boris
Published: September 2003

Different capillary electromigration techniques were employed to resolve geometrical isomers of sorbic acid, decadienoic acid, and ethyl sorbate. Since these substances differ in their polarity, shape, and size, various electromigration approaches were investigated to separate the four geometrical isomers of each compound. With capillary electrophoresis (CE) modified with a cyclodextrin (β‐CD) the four isomers of sorbic acid were separated using a buffer that consists of 60 mM tetraborate and 8 mg/mL β‐CD. The separation of decadienoic acid geometrical isomers was not possible, even at elevated tetraborate and cyclodextrin concentrations. The four isomers of decadienoic acid were successfully separated using micellar electrokinetic chromatography (MEKC) with a buffer consisting of 30 mM tetraborate and 100 mM SDS and microemulsion electrokinetic chromatography (MEEKC). Ethyl sorbate is the least polar of all the studied substances and its isomers could not be separated by MEKC or MEEKC. The resolution was improved and isomers were fully separated using capillary electrochromatography (CEC) with ODS stationary phase and a mobile phase consisting of 10 mM boric acid in 50% acetonitrile. Minor differences in the polarity and the shape of isomers and high resolving power of the applied techniques were sufficient for separation of very similar compounds. We have shown that versatile electromigration techniques can be applied for separation of geometrical isomers of dienoic acids and their esters.
HPLC‐DAD in identification and quantification of selected coumarins in crude extracts from plant cultures of Ammi majus and Ruta graveolens
Authors: Kamiński Marian , Kartanowicz Rafał , Kamiński Marcin M. , Królicka Aleksandra , Sidwa‐Gorycka Matylda , Łojkowska Ewa , Gorzeń Wojciech
Published: September 2003

This paper describes a method for the separation and determination of selected coumarins and furanocoumarins in the crude extracts from plant tissue cultures of Ammi majus hairy roots and Ruta graveolens cell suspensions, cultured in vitro, separately or together as co‐cultures. The usefulness of the three main components of the eluent used in reversed‐phase high performance liquid chromatographic analysis, namely: methanol (MeOH), acetonitrile (ACN), and tetrahydrofuran (THF), and different elution programs, was assessed. In the optimal analytical method a Lichrospher® RP‐18e 5‐μm column, a THF‐MeOH elution gradient, and a UV/VIS DAD detector were used. Due to the presence of many different compounds in the investigated plant extracts, the use of a UV/VIS DAD detector was essential. Coumarins were identified by comparison of their UV spectra with those of the analytical standards, and characterization of peak purity.
Isolation and determination of carbendazim residue from wheat grain by matrix solid‐phase dispersion and HPLC
Authors: Michel Monika , Buszewski Bogusław
Published: September 2003

Carbendazim residues were analyzed by column‐switching high‐performance liquid chromatography (HPLC) with photodiode array detection (PDA). The active ingredient was extracted by matrix solid‐phase dispersion (MSPD) from wheat grain on an acidic silica gel column using a methanol‐dichloromethane mixture. The recovery rate for fortified samples was 87.3 ± 3.3% with a standard deviation (SD) of 2.9%. The detection limit was 0.02 μg/mL. The method was applied to the determination of carbendazim residues in wheat grain samples from a treated field.
A comparative study of hydrophobicity of octadecyl and alkylamide bonded phases based on methylene selectivity
Authors: Gadzała‐Kopciuch Renata , Buszewski Bogusaław
Published: September 2003

The conformational dynamics of home‐made monomeric and polymeric (octadecyl – C18 and alkylamide – AP) stationary phases have been investigated by analyzing the dependence of retention on the reciprocal temperature for different organic compounds. Theoretical considerations were based on the results of methylene selectivity determination. Two selected PAHs – naphthacene and benzo[a]anthracene, whose structures differ in the position of the ring – were chosen as solutes to study the thermodynamics of retention behavior. Standard enthalpies (ΔH 0) were obtained from the slope of the plots of the capacity factor logarithm (ln k) against the reciprocal temperature (1/T), i. e. van't Hoff plots, in a temperature range from 285 to 315 K. The conformation of the stationary phase (monomeric and polymeric) structure and the length of bonded ligands with their specific functional (N‐acylamide) groups had a significant effect on retention.
New method for bonding an adsorbent film to the walls of capillary columns
Authors: Wawrzyniak Rafał , Wasiak Wiesław
Published: September 2003

A new method for immobilisation of an adsorbent on the wall of a capillary column ensures high thermal and mechanical stability of the resulting coating. The method can be applied to a variety of adsorbents of natural or synthetic origin. Its effectiveness is illustrated by results obtained for coating with modified silica or molecular sieve 13X.
Determination of benzene, toluene, ethylbenzene, and xylenes in urine by purge and trap gas chromatography
Authors: Brčić Irena , Skender Ljiljana
Published: September 2003

A method for determination of benzene, toluene, ethylbenzene, and xylenes (BTEX) in urine is described. Determination is performed by dynamic headspace (purge and trap) gas chromatography with photoionization detection. The features of the described method, i.e. detection limits of 15–35 ng L–1, relative standard deviations of 0.2–10%, accuracy of 80–100%, removal of interference of many compounds present in urine, sharp chromatographic peaks because of cryogenic refocusing, no sample preparation, make it convenient for biological monitoring of exposure to low levels of BTEX. However, the method is time‐consuming and sophisticated.
Purification of peanut proteins for further use in affinity chromatography and as immunogens
Authors: Baumgartner Sabine , Hemetsberger Claudia , Drs Elisabeth , Pichler Harald , Krska Rudolf
Published: September 2003

Chickens were immunised with peanut protein extracts. Because of the high cross reactivity, the lgY antibodies were purified by means of an affinity column. An ion chromatographically purified peanut protein fraction was therefore coupled to the affinity support material and this column was used for further lgY purification.
Increased Resolution of Macromolecules with Agarose Gel Electrophoresis Compared with Polyacrylamide Gel Electrophoresis
Authors: Aksoy Nurten , Unlu Sebnem
Published: September 2003

Polyacrylamide gel electrophoresis (PAGE) is routinely used for electrophoretic characterization of biomolecules. In this study we demonstrate that this technique is quite useful for the characterization of small molecules, however, it becomes inadequate for the resolution of high‐molecular‐weight macromolecules like MUC2 mucins. We show that agarose gel electrophoresis (AGE) constitutes a better medium through which MUC2 macromolecules can penetrate and hence be resolved. MUC2 molecules obtained from PC/AA (a benign colonic adenoma cell line) were extracted, and their molecular weights (varying between 15–32 × 106 Da) determined using Laser Light Scattering (LLS). These mucin molecules were reduced until 5–6 × 106 subunits were obtained. The reduced and unreduced mucin molecules were run on an AGE and Western blotting and visualized, but were too large for PAGE. For this reason, the mucin subunits were treated with trypsin to obtain 500–600 kDa fragments. These tryptic fragments were then run on PAGE and AGE, and their resolutions compared. We conclude that AGE is a more useful electrophoretic method for characterization of macromolecules like mucin glycoproteins than PAGE.

Agarose gel electrophoresis of PC/AA cell layer extract (U: unreduced, intact form, R: reduced form).

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Agarose gel electrophoresis of PC/AA cell layer extract (U: unreduced, intact form, R: reduced form).
Chiral Recognition Sites Converted from Tetrapeptide Derivatives Adopting Racemates as Print Molecules
Authors: Yoshikawa Masakazu , Izumi Jun‐ichiro
Published: September 2003

Molecularly imprinted polymeric membranes were prepared from polystyrene resin bearing tetrapeptide derivatives H‐Asp(OcHex)‐Leu‐Asp(OcHex)‐Glu(OBzl)‐OCH2‐ (DLDE) consisting of D‐amino acid residues or L‐amino acid residues. The tetrapeptide derivatives were converted into chiral recognition sites by using not only an optically pure Boc‐Trp but also racemic Boc‐Trps as a print molecule. The chiral recognition ability depends on the combination of the absolute configuration of the print molecule and that of constituting amino acid residues. The membrane prepared from a DLDE derivative consisting of D‐amino acid residues and imprinted by Boc‐D‐Trp recognized the D‐isomer in preference to the corresponding L‐isomer and vice versa. In the present study, it was also made clear that racemic print molecules were effective in generating chiral recognition sites. The affinity constant of the generated chiral recognition site was determined to be 9.6 × 103 mol−1 · dm3, which was independent of the molecular imprinting conditions. Enantioselective permeation was attained by applying electrodialysis. An optimum permselectivity of 5.9, which corresponds to the adsorption selectivity, was attained.

Summary of the molecularly imprinted polymeric membranes studied.

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Summary of the molecularly imprinted polymeric membranes studied.
Physical Hydrogels of Poly(vinyl alcohol) with Different Syndiotacticity Prepared in the Presence of Lactosilated Chitosan Derivatives
Authors: Masci Giancarlo , Husu Ivan , Murtas Susanna , Piozzi Antonella , Crescenzi Vittorio
Published: September 2003

Poly(vinyl alcohol) (PVA) physical hydrogels were prepared by repeated freeze–thawing cycles using aqueous solutions of two PVA samples having different degrees of syndiotacticity, a‐PVA and s‐PVA with 55% and 61% of syndiotactic diads, respectively. The hydrogels were prepared in the presence of different amounts of lactosilated chitosan derivatives (LC) of different molecular weight. The PVA stereoregularity was found to have a dramatic effect on the amount of PVA incorporated into the hydrogels, leading to remarkable differences in the swelling degree and porosity of a‐PVA and s‐PVA hydrogels. A significant amount of LC was retained in the hydrogels after equilibrium swelling. The swelling of the a‐PVA hydrogels was found to increase significantly by increasing the amount of LC while it was only slightly increased in the case of s‐PVA hydrogels. The amount of LC released after equilibrium swelling was lower when chitosan derivatives with higher molecular weights were used. Increased initial concentrations of LC resulted in much higher porosity of the hydrogels. TGA and DSC studies showed that LC is stabilized by the incorporation in the PVA hydrogels. The melting temperature of the crystalline regions of PVA was not significantly influenced by LC. Conversely, the extension of the crystalline domains increased in the presence of LC. The retention of a chitosan derivative bearing β‐D‐galactose side chain residues makes these hydrogels potentially useful as scaffolds for hepatocytes culture.

Scanning electron micrographs of PVA‐LC hydrogels: (a) a‐PVA; (b) a‐PVA/LC150 80:20; (c) a‐PVA/LC150 50:50.

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Scanning electron micrographs of PVA‐LC hydrogels: (a) a‐PVA; (b) a‐PVA/LC150 80:20; (c) a‐PVA/LC150 50:50.
Bilirubin Removal from Human Plasma with Albumin Immobilised Magnetic Poly(2‐hydroxyethyl methacrylate) Beads
Authors: Rad Abbas Yousefi , Yavuz Handan , Kocakulak Mustafa , Denizli Adil
Published: September 2003

Bioaffinity separation has a unique and powerful role as a support tool in the removal of toxic substances from human plasma. Magnetic beads have advantages as supports in comparison to conventional nonmagnetic beads because of low pressure drop, high mass transfer rates, and good fluid‐solid contact. In addition, they eliminate internal diffusion limitations. Human serum albumin (HSA) immobilised onto magnetic poly(2‐hydroxyethyl methacrylate) (mPHEMA) beads were investigated as an adsorbent for the selective bilirubin removal from human plasma. The mPHEMA beads were prepared by a modified suspension polymerisation. HSA was covalently coupled to the mPHEMA beads. Bilirubin adsorption was investigated from hyperbilirubinemic human plasma on the mPHEMA beads containing different amounts of immobilised HSA, (between 11–100 mg/g). The nonspecific bilirubin adsorption on the unmodified mPHEMA beads was 0.47 mg/g. Higher bilirubin adsorption capacities, up to 64.7 mg/g, were obtained with the HSA‐immobilised magnetic beads. Bilirubin adsorption increased with increasing temperature.

Effect of HSA loading on bilirubin adsorption.

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Effect of HSA loading on bilirubin adsorption.
Structure of Escherichia coli dUTPase in Solution: A Small Angle Neutron Scattering Study
Authors: Vertesse Beata G. , Magazù Salvatore , Mangione Alfonso , Migliardo Federica , Brandt Astrid
Published: September 2003

The present study investigates shape properties of the enzyme dUTPase from Escherichia coli in the solution phase. In this work small angle neutron scattering (SANS) findings on dUTPase/D2O solutions for temperature values of T = 8 °C and T = 37 °C are presented. The analysis of SANS data, carried out by using a prolate ellipsoid core/shell model fitting and the well‐known Guinier and Zimm analysis procedures allows the characterization of the shape of the protein in solution. By means of the comparison with experimental and theoretical data existing in literature on dUTPase in the crystalline state, we find that the protein in solution maintains its dimensions before the denaturation process. Furthermore, by analyzing the SANS spectra of dUTPase/D2O/trehalose solutions, we emphasize the bioprotective effects of trehalose on the protein.

Structure of dUTPase.

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Structure of dUTPase.
Structural Characterization and Enzymatic Degradation of α‐, β‐, and γ‐Crystalline Forms for Poly(β‐propiolactone)
Authors: Furuhashi Yukiko , Iwata Tadahisa , Kimura Yoshiharu , Doi Yoshiharu
Published: September 2003

A structural comparison of three different crystalline forms of poly(β‐propiolactone) (PPL) was carried out by wide‐angle X‐ray diffraction, Fourier‐transform infrared spectroscopy, and differential scanning calorimetry. The α‐form in a hot‐drawn and annealed film represents a 21 helix conformation. The β‐form in a cold‐drawn and annealed film represents a planar zigzag conformation. The γ‐form in an oriented sedimented mat of solution‐grown chain‐folded lamellar crystals also implies a planar zigzag conformation. The solution‐cast film depicts similar outlines with the γ‐form in lamellar crystals in all the experimental measurements, suggesting that the molecular chain in the solution‐cast film has a planar zigzag conformation. While elongation at break decreased, tensile strength and Young's modulus increased with an increase in the crystallinity, independent of the crystalline forms. The influence of the enzymatic degradation of these crystal structures has been investigated by using an extracellular PHB depolymerase purified from Ralstonia pickettii T1. The rate of degradation was in the order of β‐form > α‐form > solution‐cast (γ‐form) film, and the different surface morphologies after partial enzymatic degradation were observed in scanning electron micrographs. It is suggested that the crystal structure is one of the important factors for determining the rate of degradation together with crystallinity.

Enzymatic degradation profiles of poly(β‐propiolactone) films.

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Enzymatic degradation profiles of poly(β‐propiolactone) films.
The role of alloying elements in commercial alloys for corrosion resistance in oxidizing‐chloridizing atmospheres. Part II: Experimental investigations
Authors: Bender R. , Schütze M.
Published: September 2003

In an extensive study the role of the alloying elements in commercial alloys for corrosion resistance was studied in air without and with 0.1 and 2 vol.% Cl2, respectively. In the first part of this paper [1] the thermodynamic fundamentals were discussed on the basis of the new concept of the quasi‐stability diagrams. The second part which is presented here reports the results from investigations at 650, 800 and 1000°C and testing times up to 1000 hrs where 14 commercial alloys were tested with regard to their corrosion behavior. The materials were selected so that the role of the alloying elements Mo, C, Si, Al, N, Fe, Ni and Cr would be evident from the results. The exposure tests were followed by extensive microstructural analyses of the corrosion scales and the metal subsurface zones so that type, mechanism and extent of corrosion could be characterized in great detail. At the end a ranking was possible of the different materials and with regard to the detrimental or beneficial role of the different alloying elements. The present results thus provide a much deeper insight into materials resistance in oxidizing‐chloridizing environments at high temperatures.
Corrosion of carbon steel in filling material in an urban environment
Authors: Norin M. , Vinka T.‐G.
Published: September 2003

The corrosion process of carbon steel in soil has been investigated, in particular the influence of the soil of an urban environment. A field test was carried out with test panels buried in trenches. Localized and uniform corrosion rates were evaluated after 1 and 3 years. Soil samples from points adjacent to the panels were analyzed with respect to a number of physical and chemical parameters believed to influence the corrosion process. Corrosion products were analyzed and identified. The study shows that the localized corrosion rate of soil buried constructions may be remarkably high in a filling material in comparison to other soils. The heterogeneity of the soil seems to have a greater influence on the localized corrosion rate than the chemical composition of the soil. However, the uniform corrosion rate was comparatively low in the heterogeneous filling material. Both the high alkalinity in the soil water and the groundwater, and the high total hardness of the soil water in the filling material seem to reduce the uniform corrosion rate. Corrosion rate determinations with commercial probes is also discussed. The linear polarization resistance (LPR), the electric resistance (ER) and the corrosion potential measurement techniques are compared. All probes showed a seasonal variation in corrosion rate. The measurements with commercial probes were associated with some problems, mostly a result of poor contact between the probes and the soil.
The hot corrosion behaviour of HVOF sprayed MCrAlX coatings under Na2SO4 (+NaCl) salt films
Authors: Pahlavanyali S. , Sabour A. , Hirbod M.
Published: September 2003

The hot corrosion behaviour of two NiCoCrAlYTa and CoCrAlYSi HVOF sprayed coatings and a CoCrAlY VPS coating were investigated under laboratory conditions at 900°C using a synthetic gas atmosphere containing sulphur as an impurity. All the coatings tested showed good protection under Na2SO4 salt films. In the presence of NaCl in the Na2SO4 salt films, the corrosion rates of low Al containing coatings increased considerably but the NiCoCrAlYTa coating with higher Al content still revealed good performance. It is suggested that NaCl in the salt film causes premature failure of the protective scale and reduces the incubation period of corrosion in the coatings of lower Al content. Furthermore, it seems that the finely dispersed Al rich oxide particles in the sprayed and heat‐treated HVOF coating microstructure do not lead to internal corrosion. The experimental investigations include short‐term corrosion kinetic measurements and SEM analyses.
An in‐situ FT‐IR investigation of the anodic behaviour of WC‐Co hardmetal
Authors: Bozzini B. , De Gaudenzi G. P. , Mele C.
Published: September 2003

An in‐situ FT‐IR spectroelectrochemical and voltammetric study of the corrosion of a WC‐Co hardmetal grade is reported in this communication. A slightly acidic sulphate solution is considered. The potential‐ and time‐dependent anodic formation of CO2 and Co(OH)2 can be followed with the variation of the vibrational spectra. The formation of CO2 occurs at the same potential at which tungsten oxidation starts to be detected and the breakdown of passivity can be observed by electrochemical methods. Our results suggest that a threshold potential exists for the oxidation of WC in WC‐Co, giving rise to the concomitant oxidation of tungsten and carbon at more noble potentials than those typical for the oxidation of the individual elements.
Study on corrosion of steels in marine environment by corrosion simulation device
Authors: Xiang B. , Zhang J. , Duan J. Z. , Hou B. R.
Published: September 2003

Three kinds of steels were studied using electrically connected hanging specimen in the corrosion simulation device and offshore long scale hanging specimen. The experimental results obtained by the two methods show that the device can better reflect the offshore corrosion environment. A Ni‐Cu‐P steel specimen was studied through analysis of the specimen's corrosion products and corrosion types. The surface of the samples before and after the removal of the rust layer produced by these two methods were observed and compared after some experiments. The microstructure of the corrosion products under different marine environments were analyzed and compared through IR. It indicated good correlation between the electrically connected hanging specimen method and the long scale hanging specimen method.
Biodegradable Polylactide and Its Nanocomposites: Opening a New Dimension for Plastics and Composites
Authors: Ray Suprakas Sinha , Okamoto Masami
Published: September 2003

The academic and industrial aspects of the preparation, characterization, mechanical and materials properties, crystallization behavior, melt rheology, and foam processing of pure polylactide (PLA) and PLA/layered silicate nanocomposites are described in this feature article. Recently, these materials have attracted considerable interest in polymer science research. PLA is linear aliphatic thermoplastic polyester and is made from agricultural products. Hectorite and montmorillonite are among the most commonly used smectite‐type layered silicates for the preparation of nanocomposites. Smectites are a valuable mineral class for industrial applications because of their high cation exchange capacities, surface area, surface reactivity, adsorptive properties, and, in the case of hectorite, high viscosity, and transparency in solution. In their pristine form, they are hydrophilic in nature, and this property makes them very difficult to disperse into a polymer matrix. The most common way to overcome this difficulty is to replace interlayer cations with quaternized ammonium or phosphonium cations, preferably with long alkyl chains. In general, polymer/layered silicate nanocomposites are of three different types: (1) intercalated nanocomposites, in which insertion of polymer chains into the layered silicate structure occurs in a crystallographically regular fashion, regardless of polymer to layered silicate ratio, with a repeat distance of few nanometer; (2) flocculated nanocomposites, in which intercalated and stacked silicate layers are sometimes flocculated due to the hydroxylated edge–edge interactions between the silicate layers; (3) exfoliated nanocomposites, in which individual silicate layers are uniformly distributed in the polymer matrix by average distances that totally depend on the layered silicate loading. This new family of composite materials frequently exhibits remarkable improvements in its material properties when compared with those of virgin PLA. Improved properties can include a high storage modulus both in the solid and melt states, increased flexural properties, a decrease in gas permeability, increased heat distortion temperature, an increase in the rate of biodegradability of pure PLA, and so forth.

Illustration of the biodegradability of PLA and various nanocomposites.

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Illustration of the biodegradability of PLA and various nanocomposites.
Novel Chromophore‐Functionalized Poly[2‐(trifluoromethyl) adamantyl acrylate‐methyl vinyl urethane]s with High Poling Stabilities of the Nonlinear Optical Effect
Authors: Briers David , Koeckelberghs Guy , Picard Isabel , Verbiest Thierry , Persoons André , Samyn Celest
Published: September 2003

Nonlinear optical vinyl polymers with high glass transition temperature (Tg) were prepared by the functionalization of a fluorinated acrylate‐methyl vinyl isocyanate copolymer. A modified pathway to obtain a thiophene bridged chromophore was worked out. Poled films of the polymers show a fairly high and stable nonlinear optical response, even at elevated temperatures.

The thiophene‐bridged chromophore, based on a substituted dicyanomethylene‐dihydrofuran acceptor, synthesized here.

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The thiophene‐bridged chromophore, based on a substituted dicyanomethylene‐dihydrofuran acceptor, synthesized here.
Chiral Biomineralization: Mirror‐Imaged Helical Growth of Calcite with Chiral Phosphoserine Copolypeptides
Authors: Sugawara Tetsunori , Suwa Yukie , Ohkawa Kousaku , Yamamoto Hiroyuki
Published: September 2003

TheO‐phospho‐L‐serine [Ser(P)] containing peptides and proteins play an important role in controlling the morphology of biominerals. The poly[Ser(P)] and copoly[Ser(P)xAspy] affect the calcium carbonate (CaCO3) morphology and polymorph. The CaCO3helical structures were obtained in the presence of copoly[Ser(P)75Asp25]. When theL‐copolymer was used as an additive, a clockwise P twisted spiral morphology was formed. On the other hand, when usingD‐copolymer, a counterclockwise M twisted spiral morphology was obtained.

Optical micrographs of chiral morphologies of CaCO3in the presence of a)L‐copolymer and b)D‐copolymer.

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Optical micrographs of chiral morphologies of CaCO3in the presence of a)L‐copolymer and b)D‐copolymer.
Characterization of Defined Metal‐Containing Supramolecular Block Copolymers
Authors: Meier Michael A. R. , Lohmeijer Bas G. G. , Schubert Ulrich S.
Published: September 2003

The characterization of metal‐containing supramolecular polymers by gel permeation chromatography (GPC) or matrix‐assisted laser desorption ionisation time‐of‐flight mass spectrometry (MALDI‐TOF MS) is complicated because of the interaction of the charged materials with the GPC column material in the first case and fragmentation due to the applied laser energy in the latter case. In this contribution we report recent advances made for the characterization of supramolecular polymers based on terpyridine metal complexes utilizing GPC and MALDI‐TOF MS. In particular for GPC analysis, the choice of solvent and additive was found to be crucial for a successful characterization. Furthermore, MALDI‐TOF MS spectra of these compounds are not straightforward to interpret. Both aspects are discussed in detail with the result of a better understanding and improved analysis possibilities of the mentioned supramolecular polymers.

A GPC‐coupled in‐line diode array spectrum of one of the complexes investigated here.

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A GPC‐coupled in‐line diode array spectrum of one of the complexes investigated here.
Polyelectrolytes in a Historic Setting
Authors: Scheler U.
Published: September 2003

This section contains reports on topical conferences. Reports are usually written at the request of the editorial office, but unsolicited contributions are also welcome. Suggestions should be sent to the editorial office of the Macromolecular journals, preferably by E‐mail to macromol@wiley‐vch.de.