Direct methanol fuel cells for vehicular applications

Dramatic technological advances for the proton exchange membrane fuel cell have focused attention on this technology for motor vehicles. The fuel cell vehicles (FCVs) have the potential to compete with the petroleum-fueled internal combustion engine vehicles (ICEVs) in cost and performance while effectively addressing air quality, energy insecurity, and global warming concerns. Methanol being a liquid can be easily transported and can be supplied from the existing network of oil company distribution sites. Recently, combining improved catalysts with fuel cell engineering, it has been possible to overcome some of the difficulties that have frustrated previous research and development efforts in realizing a commercially viable direct methanol fuel cell. Direct methanol fuel cells (DMFCs) with power densities between 0.2 and 0.4 W/cm² at operational temperatures in the range 95–130 °C have been developed. These power densities are sufficient to suggest that stack construction is well worth while. This paper reviews recent advances and technical challenges in the field of DMFCs. Received: 27 May 1997 / Accepted: 25 November 1997     

Sensitive synchronous spectrofluorimetric methods for the determination of naproxen and diflunisal in serum

The interaction of diflunisal and naproxen with several surfactants was studied. Spectrofluorimetric methods were developed for the determination of both drugs in sodium dodecylsulfate micellar medium. The mixture of these drugs was resolved by synchronous fluorescence spectrometry using two scans. At Δλ = 20 nm, only naproxen yields a detectable signal that is unaffected by the presence of diflunisal. At Δλ = 110 nm the signal of diflunisal is not influenced by the presence of an up to 3-fold excess of naproxen. Mixtures containing naproxen/ diflunisal in ratios from 50:1 to 1:50 were analyzed with good results. The linear calibration ranges of both drugs were ca 0.02–2.0 μg mL^–1. The method has satisfactorily been applied to a mixture of both drugs in serum. Received: 7 October 1997 / Revised: 3 December 1997 / Accepted: 7 December 1997     

Qualification and validation of software and computer systems in laboratories

 Software and computer systems are tested during all development phases. The user requirements and functional specifications documents are reviewed by programmers and typical anticipated users. The design specifications are reviewed by peers in one to two day sessions and the source code is inspected by peers, if necessary. Finally, the function and performance of the system is tested by typical anticipated users outside the development department in a real laboratory environment. All development phases including test activities and the final release follow a well-documented procedure. Received: 17 May 1997 · Accepted: 30 June 1997     

Key requirements for introducing quality assurance in measurement laboratories

 The implementation of a quality assurance system is fraught with difficulties. However, these difficulties may be overcome if the laboratory uses suitable means to facilitate the process. It is necessary to mobilise the intelligence and energy of all members of the laboratory. In order to command adherence, the project must be shared, and this necessitates a major effort by all concerned. Communication is a major factor in obtaining the support of all parties. Six important steps must be distinguished: – Defining quality policy – Creating awareness, information, training – Creating a quality structure – Establishing a deadline for obtaining accreditation – Progressive implementation – Experimentation and validation. Even if the task of obtaining and maintaining accreditation remains difficult, it clearly promotes a minimum level of organisation and stepwise progress in quality assurance. The laboratory must keep improving its quality system, using European Standard EN 45001 as an effective management model. Received: 9 April 1997 · Accepted: 11 September 1997     

Polyaniline dispersions 7. Dynamic light scattering study of particle formation

 When aniline is oxidized in the presence of colloidal silica, composite polyaniline–silica particles of submicrometer size are obtained. Dynamic light scattering was used to monitor the course of dispersion polymerization of aniline and the formation of particles. The increase of a hydrodynamic radius of particles was observed as polyaniline had been produced. Additional increase in particle size after polymerization has also been recorded. The rate of aniline polymerization was found to increase with increasing temperature in the range 0–50 °C. Well-defined particles are formed below 30 °C while above this temperature the colloidal stability of the resulting systems is limited. The activation energy of aniline polymerization was estimated. Received: 24 February 1997 Accepted: 7 May 1997     

Supercritical fluid extraction combined with solid phase extraction as sample preparation technique for the analysis of β-blockers in serum and urine

A method is developed for the determination of β-blockers in serum and urine at levels of 0.5 μg/mL. The technique uses a combination of solid phase extraction (SPE) with in situ derivatization and supercritical fluid extraction (SFE) with subsequent gas chromatography mass spectrometry. The optimization of the SFE step shows that a static extraction period can be eliminated. The method gives good linearity (r = 0.991–0.999) and repeatability in the concentration range of 0.5 to 5 μg/mL. Relative standard deviations for oxprenolol, propanolol and metoprolol were less than 5% in serum and 5–11% in urine. Received: 23 May 1997 / Revised: 28 July 1997 / Accepted: 5 August 1997     

Characterization of a covalent triazine-humic acid conjugate by gas chromatography

The aim of the described method was the characterization of a “atrazine-mercaptopropionic acid” humic acid conjugate, which was required for the calibration of immunoassays to determine bound residues. In order to estimate the amount of bound triazine, an oxidative nucleophilic substitution reaction of the covalently linked “atrazine-mercaptopropionic acid” to a new triazine derivative “atrazine-methoxyethanol” was performed. This cleavage product was quantified by gas chromatography. The conditions for this cleavage procedure were optimized and applied to the “atrazine-mercaptopropionic acid” humic acid conjugate and to a humic acid blank. The amount of bound “atrazine-mercaptopropionic acid” was calculated to 16.6 ± 2.5 μmol triazine per gram humic acid, which is equivalent to 0.39 ± 0.07% atrazine. Received: 7 August 1997 / Accepted: 12 September 1997     

Quality [r]evolution in diabetes care

 To implement the St. Vincent Declaration Action Programme, initiatives have been started in the quality development of diabetes care across Europe. The main elements of the quality development cycle implemented in our hospital were realized by the use of the software package ‘CamitPro’ and participation in ‘the DiabCare Q-net NL’ network. From 1997 to 1999, 955, 1468, and 1624 patients with diabetes mellitus type 2 were integrated in the DiabCare Q-net NL network by using ‘CamitPro’ software, respectively. These patients showed substantial improvement in all of the clinical measures monitored. In addition, there was a drop in HbA_1c level. From 1997 to 1999, an HbA_1c interval of 5.1%–8.3% (mean up to mean +4SD) was recorded for 66%, 76% and 81% of the patients, respectively. An extension of the use of the software to a pan-European level should markedly improve diabetes care throughout the community. Received: 10 July 2000 / Accepted: 10 July 2000     

Immuno-affinity columns versus conventional clean-up: a method-comparison study for the determination of zearalenone in corn

The efficiency of a modern analytical method employing immuno-affinity columns (IACs) is compared to a well established traditional technique with respect to the determination of zearalenone (ZON) in corn in the μg/kg range. Despite of a constant error of about 4 μg/kg in the examined working range of 10–200 μg/kg, analytical data obtained from the analysis of spiked and naturally contaminated samples showed good correspondence for the compared methods. The performance characteristics of immuno-affinity-chromatography as a new clean-up technique for the determination of ZON in corn is reported for the first time and compared to a conventional clean-up procedure Received: 25 March 1997 / Revised: 5 May 1997 / Accepted: 12 May 1997     

Determination of cobalt by substoichiometric extraction with β-hydroxy-naphthaldoxime

A substoichiometric radiochemical solventextraction method is described for the determination of cobalt, employing β-hydroxy-naphthaldoxime and chloroform as reagent and extractant, respectively. The extraction behaviour of the complex of cobalt with the reagent in the pH-range 8–9.5 and the effects of various metal ions on the extraction are critically studied. The method is used to determine the cobalt content in some pharmaceutical drugs. Received: 10 January 1997 / Revised: 11 March 1997 / Accepted: 25 March 1997     

Is traceability an exclusive property of analytical results? An extended approach to traceability in chemical analysis

The need to adapt the definition of traceability in the Metrological Dictionary of ISO to the growing use of this concept in Analytical Chemistry aroused the broader, more flexible proposal expounded in this paper which aims to be closer to the bench level. The traceability concept is addressed in a hierarchical manner by ranking the different notions to which the qualifier “traceable” applies (results, standards, equipment and samples) in such a way that it is compatible with the ISO definition. Relationships among them and with classical analytical properties are also exposed. Received: 12 May 1997 / Revised: 22 July 1997 / Accepted: 25 July 1997     

Is traceability an exclusive property of analytical results? An extended approach to traceability in chemical analysis

The need to adapt the definition of traceability in the Metrological Dictionary of ISO to the growing use of this concept in Analytical Chemistry aroused the broader, more flexible proposal expounded in this paper which aims to be closer to the bench level. The traceability concept is addressed in a hierarchical manner by ranking the different notions to which the qualifier “traceable” applies (results, standards, equipment and samples) in such a way that it is compatible with the ISO definition. Relationships among them and with classical analytical properties are also exposed. Received: 12 May 1997 / Revised: 22 July 1997 / Accepted: 25 July 1997     

Determination of persistent organochlorine compounds in blood by solid phase micro extraction and GC-ECD

Biomonitoring of persistent organochlorine compounds in blood using the solid phase microextraction technique (SPME) and gas chromatography with electron capture detection (GC-ECD) is described. Polar substances as tri-, tetra- and penta-chlorophenols are analyzed simultaneously with less polar compounds such as hexachlorobenzene (HCB), α-, β-, and γ-hexachlorocyclohexane (HCH), dichlorodiphenyltrichloroethane (DDT) and its derivatives and with some important congeners of the polychlorinated biphenyls (PCB). No derivatization is needed for the determination of the phenolic compounds. The results show a good reproducibility down to the lower μg/L-region. The method is very fast and of low cost compared to the classic extraction and determination procedures. Received: 7 July 1997 / Revised: 6 October 1997 / Accepted: 21 October 1997     

The effect of temperature on lithium intercalation into carbon materials

The effects of temperature on lithium intercalation into non-graphitized carbonized cloth from various electrolytes have been studied. The open-circuit potential (o.c.p.) of the intercalates shifts in the negative direction as the temperature is raised. The average temperature coefficient of the o.c.p. is equal to −0.04 mV·K⁻¹ in the range from −35 to +45 °C. Intercalation-deintercalation kinetics was studied by the galvanostatic technique. It was shown that this process is quasi-ohmic at room and higher temperatures and has activation-ohmic control at lower temperatures. The effective activation energy of intercalation-deintercalation is about 20kJ·mol⁻¹. Intercalates are corroded in all electrolytes, the corrosion rate being drastically increased as the temperature is raised. The apparent activation energy of corrosion is 120–150 kJ·mol⁻¹. The corrosion rate is suggested to be controlled by cathodic reduction of electrolyte components. Received: 11 April 1997 / Accepted: 8 September 1997     

A pilot study for the preparation of a new Reference Material based on antarctic krill

The preparation of new Certified Reference Materials (CRMs) of antarctic matrices forms the backbone of an ongoing project in the framework of the Italian National Program for Antarctic Research. The first CRM of this kind (MURST-ISS-A1 Antarctic Marine Sediment) is already available. The second phase focuses on the certification of antarctic krill, a small shrimp extremely abundant in the Southern Ocean. The total mass of krill available for this purpose is approximately 44 kg and results from the combination of three different catches (Ross Sea, Marguerite Bay and Livingston Island, respectively). The quantification of the following elements in the raw mass appears to be affordable by current analytical techniques, values being in the range of (in μg/g) 0.11–0.30 for As, 0.03–0.12 for Cd, 0.06–0.23 for Cr, 6.1–21 for Cu, 5.7–7.6 for Fe, 0.005–0.008 for Hg, 0.7–1.2 for Mn, 0.013– 0.077 for Ni, 0.04–0.57 for Pb and 12–16 for Zn. On the other hand, the average values ascertained in freeze-dried krill are as a rule one order of magnitude higher, i.e., (in μg/g), 3.2 for As, 0.6 for Cd, 1.8 for Cr, 75 for Cu, 61 for Fe, 0.025 for Hg, 4.6 for Mn, 0.7 for Ni, 2.1 for Pb and 81 for Zn. Information on the pretreatment of krill and details on the planned certification campaign are also given. Received: 10 June 1997 / Revised: 24 September 1997 / Accepted: 28 September 1997     

Solid state structural aspects of electrochemically prepared poly (p -phenylene) thin films – crystalline order and spherulite morphology

The electrochemical polymerization of benzene via the microemulsion approach yields highly crystalline and anisotropic “spherulitic” polyparaphenylene (PPP) thin films. The crystalline order and the origin of spherulite morphology are discussed. Received: 29 July 1997 / Accepted: 27 October 1997     

Monosegmented flow-analysis of slow enzymatic reactions: Determination of triglycerides in serum

 A monosegmented flow system (MCFA) is proposed to achieve slow enzymatic spectrophotometric determinations, here applied to the determination of triglycerides in blood serum. The sample (4.5 μL), enzymatic reagent (150 μL) and an air plug (100 μL) are simultaneously inserted into a carrier stream buffered to pH 7.9 (Tris ⋅ HCl). In order to avoid the cumbersome step of air removal, a relocating detector was used. This system handles about 60 samples/h, yielding precise results (r.s.d. usually<2.5%). Sensitivity is 56 mAU ⋅ L/mmol up to 6 mmol/L triglycerides. Accuracy was assessed by running 50 samples already analysed by a conventional procedure yielding the equation C_MCFA(mmol/L)=1.00(±0.04) C_Ref(mmol/L)−0.03(±0.08); r=0.990. Received: 22 January 1997/Revised: 12 March 1997/Accepted: 28 March 1997     

Reference materials for small-sample analysis

Many modern analytical techniques use small solid samples and lack proper reference materials for their calibration and quality assurance. A remedy to this deficiency may be in the development of a new genre of highly homogeneous natural matrix materials, their properties being studied with analytical techniques such as PIXE and μ-PIXE, solid sampling AAS, scanning electron microscopy in combination with electron probe X-ray microanalysis, and INAA. Suitable natural materials may be obtained in form of single cell biological materials, finely dispersed suspensions and precipitates such as air particulate matter or sediments, and by appropriate particle size reduction of complex matrices. Initial studies have been carried out on single cell green algae biomass and air particulate matter, as well as several processed materials. Narrow particle size distributions with particles preferably below 10 μm diameter may assure the desired analytical homogeneity. The determination of sampling parameters for individual measurands will ascertain the utility of a material for small-sample analysis. Received: 16 June 1997 / Revised: 24 September 1997 / Accepted: 27 September 1997     

Interfaces for data processing in surface analysis

As computer controlled instruments for surface analysis are in common use for many years, the problem of exchangeability of analytical data has attracted interest in the surface analysis community. More and more examples for the development of standarized data formats as the VAMAS format [1] and the Standard for Chromatography Data Communication from the AIA [2] have been published. There are a few attempts to establish standardized “data dictionaries” e.g. the parameter lists describing AES and XPS spectra pusblished in Surface Science Spectra [3, 4]. If several different analysis methods (such as AES, SAM, XPS, SIMS, STM, AFM, EPMA, …) are applied to the same sample, a quite independent and open approach is needed to be able to combine data of various instruments in a common data evaluation procedure. It could be the basic concept of real mutli-method analysis. The public domain software package MAXMIND has been developed, as only a standardized data exchange and storage format based on data dictionaries can guarantee a high level of independence of proprietary measurement systems. Received: 16 January 1997 / Revised: 9 May 1997 / Accepted: 14 May 1997     

Interfaces for data processing in surface analysis

As computer controlled instruments for surface analysis are in common use for many years, the problem of exchangeability of analytical data has attracted interest in the surface analysis community. More and more examples for the development of standarized data formats as the VAMAS format [1] and the Standard for Chromatography Data Communication from the AIA [2] have been published. There are a few attempts to establish standardized “data dictionaries” e.g. the parameter lists describing AES and XPS spectra pusblished in Surface Science Spectra [3, 4]. If several different analysis methods (such as AES, SAM, XPS, SIMS, STM, AFM, EPMA, …) are applied to the same sample, a quite independent and open approach is needed to be able to combine data of various instruments in a common data evaluation procedure. It could be the basic concept of real mutli-method analysis. The public domain software package MAXMIND has been developed, as only a standardized data exchange and storage format based on data dictionaries can guarantee a high level of independence of proprietary measurement systems. Received: 16 January 1997 / Revised: 9 May 1997 / Accepted: 14 May 1997