Hans Lundbäck - Academia.edu (original) (raw)

Papers by Hans Lundbäck

Analytical Letters, 1985

Abstract A flow injection manifold containing a dialyzer and reactors with immobilized galactose ... more Abstract A flow injection manifold containing a dialyzer and reactors with immobilized galactose oxidase and peroxidase was used for the determination of galactose in urine, lactose in milk and dihydroxyacetone in a biotechnological reaction medium. The ...

Advanced Drug Delivery Reviews

Journal of Aerosol Science, 1988

A laser scattering instrument was studied as a potential alternative to the cascade impactor whic... more A laser scattering instrument was studied as a potential alternative to the cascade impactor which is currently used by us to characterize the particle size distribution from Bricanyl) Turbuhaler) (Jaegfeldt et al. (1987)). Bricanyl) Turbuhaler) is a multidose dry powder ...

Journal of Aerosol Science, 1995

were 740 and 678 days during the first 250 days and 1757 and 883 days for the following 250 to 90... more were 740 and 678 days during the first 250 days and 1757 and 883 days for the following 250 to 900 days after exposure. Measurement of feces samples is consistent with the longer clearance half-times. The difference between the two systems can be explained by translocation to the lymph nodes from the lung, which in greater extent is interpreted as clearance by the HPGe detector system.

Journal of Aerosol Medicine and Pulmonary Drug Delivery, 2013

A validated method to predict lung deposition for inhaled medication from in vitro data is lackin... more A validated method to predict lung deposition for inhaled medication from in vitro data is lacking in spite of many attempts to correlate in vitro and in vivo outcomes. By using an in vivo-like in vitro setup and analyzing inhalers from the same batches, both in vitro and in vivo, we wanted to create a situation where information from the in vitro and in vivo outcomes could be analyzed at the same time. Nine inhalation products containing either budesonide or AZD4818 were evaluated. These comprised two pressurized metered dose inhalers (pMDIs), a pMDI plus a spacer, four dry powder inhalers, and two dosimetric nebulizers. In vitro, an in vivo-like setup consisting of anatomically correct inlet throats were linked to a flow system that could replay actual inhalation flow profiles through the throat to a filter or to an impactor. In vivo, total lung deposition was measured in healthy adults by pharmacokinetic methods. We could show that the amount of drug escaping filtration in a realistic throat model under realistic delivery conditions predicts the typical total lung deposition in trained healthy adult subjects in the absence of significant exhaled mass. We could further show that by using combinations of throat models and flow profiles that represent realistic deviations from the typical case, variations in ex-cast deposition reflect between-subject variation in lung deposition. Further, we have demonstrated that ex-cast deposition collected either by a simple filter or by a cascade impactor operated at a fixed flow rate using a mixing inlet, to accommodate a variable flow profile through the inhaler, predicts equally well the lung deposited dose. Additionally, the ex-cast particle size distribution measured by this method may be relevant for predicting exhaled fraction and regional lung deposition by computational models.

Journal of Aerosol Medicine, 2002

Journal of Aerosol Medicine, 2005

When measuring the aerodynamic particle size distribution of pulmonary drug products, the commonl... more When measuring the aerodynamic particle size distribution of pulmonary drug products, the commonly used instrument is a cascade impactor. For this type of analysis, a mass balance (MB) criterion, 85-115% of label claim, has been recommended by the U.S. Food and Drug Administration (FDA) to be included in the drug product specification. Using statistical model simulations, the effect of inherent product variability on the risk to fail the proposed criteria has been assessed and compared to the corresponding risk to fail the delivered dose uniformity (DDU) test. The results clearly show that the MB criterion is at odds with typical variability of orally inhaled products and seriously contributes to the risk that a typical batch would be rejected due to natural variability of the delivered dose of the product. The MB criterion is generally more difficult to comply with compared to the corresponding delivered dose uniformity (DDU) test, indicating that the proposed FDA MB specification overrules the DDU criteria as being that controlling the DDU.

Applied Microbiology and Biotechnology, 1985

A flow injection analysis (FIA) system with amperometric detection was developed for measuring hy... more A flow injection analysis (FIA) system with amperometric detection was developed for measuring hydrogen peroxide which was used as an oxygen source for immobilized cells. A constant concentration of peroxide in the reactor was maintained by processing the analytical signal in a computer programmed as a PI-regulator. The concentration of dissolved oxygen was followed using a commercial Clark-electrode. The simultaneous measurements of hydrogen peroxide and dissolved oxygen are discussed with respect to process control. Conversion of glycerol to dihydroxyacetone by Gluconobacter oxydans immobilized in calcium alginate was used as a model system. Initial specific productivity increased with increasing hydrogen peroxide concentration. However, decreases in viable counts, enzymatic activities and overall productivities were noted. Various techniques for improving operational stability are discussed.

Annals of the New York Academy of Sciences, 1987

Flow injection analysis (FIA) provides a convenient tool for the determination of carbohydrates, ... more Flow injection analysis (FIA) provides a convenient tool for the determination of carbohydrates, if a packed-bed enzyme reactor is inserted into the manifold. The reactors can be dimensioned so that the substrate is converted to products with close to 100% efficiency at the flow rate used.' The FIA concept becomes particularly powerful when additional sample pretreatment is In the work reported here, a parallel-plate dialyzer was used to remove particulate and macromolecular material from serum samples in a FIA method for galactose (FIG.

Annals of the New York Academy of Sciences, 1984

Analytical Chemistry, 1986

A new liquid membrane electrode based on an Ion assoclatlon extraction system responding to ephed... more A new liquid membrane electrode based on an Ion assoclatlon extraction system responding to ephedrlne Is described. It incorporates an ephedrlne-flavianate ion palr complex as a novel electroactive component in 1-octanol. The electrode exhibits near-Nernstian response over the concentration range of lo-* to M ephedrlne In soiutlons of pH 4-7. The electrode also responds to some neurotransmitters contalnlng the 6-ethanolamine moiety. Response tlme varies from 20 to 90 s, and interferences from many organic bases and some

Analytica Chimica Acta, 1981

Hydrogen peroxide in pickling baths for copper and copper alloys can be determined by linear swee... more Hydrogen peroxide in pickling baths for copper and copper alloys can be determined by linear sweep voltammetry with a glassy carbon electrode. The oxidation mechanism changes around 0.15 M H,O,. Catalytic decomposition was found to be much smaller at glassy carbon electrodes than at platinum electrodes. An almost linear calibration curve was obtained up to 60 mM H,O,. Interferences from Cu*+, Zn'+, Ni", Ala*, Fe'+ and Pb'+ as well as from the stabilizers were small. All measurements were made in sulphuric acid solutions. The use of hydrogen peroxide in pickling baths has increased during the past few years, as it causes fewer environmental problems than some other oxidants, e.g. chromates. The hydrogen peroxide in the baths can usually be determined precisely by visual titration using permanganate. Nevertheless, there is a need for an instrumental method which can be used either manually or automatically at the site of the baths. Pickling baths for copper and copper alloys, as well as baths for some other metals, contain 0.5-Z M sulphuric acid and 0.1-0.6 M stabilized hydrogen peroxide. The metal concentration will increase with use up to the limit set by the regeneration routine, usually 0.5 M for copper. The metal interferences considered in this work were from Cu'+, Zn*', Ni*+, Fe3+, A13+ and Pb*+. Only a few of the known methods for the determination of hydrogen peroxide can be used in samples with the mentioned compositions_ Direct electrochemical oxidation of hydrogen peroxide seemed to be the most promising one. Harrar [l] developed a coulom,etric determination of hydrogen peroxide in which the oxidation was made at a platinum anode at +0.93 V vs. SCE. Guilbault and Lubrano [2] used an amperometric oxidative detection method for enzymatically produced hydrogen peroxide. A patent has also been granted for an electrochemjcal method for hydrogen peroxide determinations [3]. Very many papers on the electrochemical properties of hydrogen peroxide have been published. Hickling and Wilson [4] studied the anodic decomposition at Pt, Au, Ni and graphite electrodes. Lingane and Lingane 153 used chronopotentiometry in a mechanistic study of the oxida

Analytica Chimica Acta, 1985

Analytica Chimica Acta, 167 (1985) 123-136 Elsevier Science Publishers BV, Amsterdam - Printed in... more Analytica Chimica Acta, 167 (1985) 123-136 Elsevier Science Publishers BV, Amsterdam - Printed in The Netherlands GALACTOSE DETERMINATION IN AN AUTOMATED FLOW-INJECTION SYSTEM CONTAINING ENZYME REACTORS AND AN ON-LINE DIALYZER BO ...

Analytica Chimica Acta, 1983

An amperometeric method is described for the determination of hydrogen peroxide in reaction media... more An amperometeric method is described for the determination of hydrogen peroxide in reaction media used for production of dihydroxyacetone from glycerol by immobilized bacteria. The H,O, was oxidized at +1.2 V vs. SCE at a glassy carbon flow-through electrode after dilution in a flow injection analysis system. Unexpected losses of H,O, response in cell-free media necessitated a study of the cause. To validate the measurements two other methods for H,O, determinations were used in parallel, a catalytic calorimetric method and an enzymatic flow injection method based on the use of immobilized peroxidase to produce a coloured product which was monitored spectrophotometrically. The three methods gave the same results. It was concluded that the responses of the methods were correct and that the loss of H,O, is real and due to reactions with dihydroxyacetone or some of its decomposition products. A reverse reaction was also observed, i.e., the production of H,O, from oxygen and decomposition products of dihydroxyacetone in an originally peroxide-free solution.