Infrared and infrared emission spectroscopy of gallium oxide α-GaO(OH) nanostructures

Infrared spectroscopy has been used to study nano- to micro-sized gallium oxyhydroxide α-GaO(OH), prepared using a low temperature hydrothermal route. Rod-like α-GaO(OH) crystals with average length of 2.5 μm and width of 1.5 μm were prepared when the initial molar ratio of Ga to OH was 1:3. β-Ga₂O₃ nano and micro-rods were prepared through the calcination of α-GaO(OH). The initial morphology of α-GaO(OH) is retained in the β-Ga₂O₃ nanorods.The combination of infrared and infrared emission spectroscopy complimented with dynamic thermal analysis were used to characterise the α-GaO(OH) nanotubes and the formation of β-Ga₂O₃ nanorods. Bands at around 2903 and 2836 cm⁻¹ are assigned to the –OH stretching vibration of α-GaO(OH) nanorods. Infrared bands at around 952 and 1026 cm⁻¹ are assigned to the Ga–OH deformation modes of α-GaO(OH). A significant number of bands are observed in the 620–725 cm⁻¹ region and are assigned to GaO stretching vibrations.     

Short-term measurements of acrolein in ambient air

Summary A method has been developed for the determination of acrolein in air samples collected by a high-volume aqueous scrubber. The aldehyde is collected as the bisulfite adduct, which is decomposed before determination of acrolein by DNPH (2,4-dinitrophenylhydrazine) derivatization and HPLC. Approximately 95% of the acrolein reacts with DNPH within 3 h at DNPH:HSO₃ molar ratios of up to 10. The method appears promising for short-term air sampling at 8 L min^–1, enabling the achievement of a detection limit of 0.2 g m^–3 for acrolein.     

Hollow fiber membrane of yttrium-stabilized zirconia and strontium-doped lanthanum manganite dual-phase composite for oxygen separation

The hollow fiber composite membrane involving Zr_0.84Y_0.16O_1.92 (YSZ) as an oxygen ionic conductor and La_0.8Sr_0.2MnO_3−δ (LSM) as an electronic conductor was explored for oxygen separation application. The hollow fiber precursor was prepared by the phase-inversion process, and transformed to a gas-tight ceramic by sintering at 1350 °C. The as-prepared fiber exhibited a thermal expansion coefficient of 11.1 × 10⁻⁶ K⁻¹ and a three-point bending strength of 152 ± 12 MPa. An oxygen permeation flux of 2.1 × 10⁻⁷ mol cm⁻² s⁻¹ was obtained under air/He gradient at 950 °C for a hollow fiber of length 57.00 mm and wall thickness 0.16 mm. The oxygen permeation flux remained unchanged when the sweeping gas was changed from helium to high concentration of CO₂. Considering the satisfactory trade-off between the permeability and stability, the YSZ–LSM hollow fiber is promising for oxygen production applications.     

Determination of Selenium(IV) by Stripping Voltammetry at a Mercury-Film Electrode

A procedure was proposed for the determination of selenium(IV) by stripping voltammetry on a mercury-film electrode at an electrolysis potential of +0.4 V versus the saturated silver–silver chloride reference electrode in a 1 M H₂SO₄ solution. The current of the cathodic peak is a linear function of the selenium(IV) concentration in the range from 5 × 10^–3 to 3 × 10^–1 mg/L (6.3 × 10^–8 to 3.8 × 10^–6 M) at a time of electrolysis of 30 s (t _el). The detection limit for selenium is 1 × 10^–4 mg/L (1.3 × 10^–9 M) at t _el = 300 s. It was shown that selenium(IV) can be determined in the presence of 10 mg/L Zn(II), 1 mg/L Cd(II), 0.5 mg/L Pb(II), and 0.2 mg/L Cu(II). A procedure for the determination of selenium in natural, mineral, and potable water was proposed.     

Determination of sulphate in natural water by flow-injection analysis

Summary Sulphate was determined in natural water samples by flow-injection analysis using dimethylsulphonazo-III as reagent. The interference by Ca was eliminated by a cation-exchanger column inserted directly after the sample injection valve. In order to ensure high sensitivity and reproducibility it was necessary to saturate the carrier solution with barium sulphate and to fill the reaction coil with ethanol-water (11) when not in use. Standard deviations were 0.94–1.2% for 6–10mg/l sulphate. The limit of detection was about 0.2mg/l. The calibration graph was linear up to 14mg/l Mg²⁺, NH ₄ ⁺ , Na⁺, K⁺, Cl^–, NO ₃ ^– , PO ₄ ^3– , HCO ₃ ^– and SiO ₃ ^2– did not interfere in the normally occurring concentrations.

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Sulfatbestimmung in natürlichem Wasser durch Flow-Injection-Analyse

Zusammenfassung Als Reagens dient Dimethylsulfonazo-III. Die Störung durch Calcium bei dieser Bestimmung wird durch eine Kationenaustauschersäule eliminiert, die direkt nach dem Probeinjektions-Ventil angeordnet ist. Zur Erhöhung der Empfindlichkeit und Reproduzierbarkeit ist es notwendig, die Trägerlösung mit Bariumsulfat zu sättigen sowie bei Nichtbenutzung des Systems den Reaktionsteil mit Ethanol-Wasser (11) zu füllen. Mit dem so modifizierten Verfahren ergaben sich Standardabweichungen von 0,94–1,2% für 6–10 mg/l Sulfat, die Nachweisgrenze liegt bei 0,2 mg/l. Die Eichkurve ist bis 14 mg/l linear. Mg²⁺, NH ₄ ⁺ , Na⁺, K⁺, Cl^–, NO ₃ ^– , PO ₄ ^3– , HCO ₃ ^– und SiO ₃ ^2– stören in den normalerweise vorkommenden Konzentrationen nicht.

     

Extraction procedures for chemical speciation of arsenic in atmospheric total suspended particles

An arsenic chemical speciation study was performed in 2000, using air filters on which total suspended particles (TSP) were collected, from the city of Huelva, a medium size city with huge industrial influence in SW Spain. Different procedures for extraction of the arsenic species were performed using water, NH₂OH.HCl, and H₃PO₄ solutions, with either microwave or ultrasonic radiation. The best optimised extraction methods were use of 100 mmol L^–1 NH₂OH.HCl and 10 mmol L^–1 H₃PO₄ and microwave radiation for 4 min. High-performance liquid chromatography coupled with hydride generation and atomic fluorescence spectrometry (HPLC–HG–AFS) was employed for determination of the arsenic species. The results from 12 TSP air filters collected on a monthly basis showed extraction was quantitative (94% with NH₂OH.HCl and 86% H₃PO₄). Only inorganic arsenic species (arsenite and arsenate) were detected. The mean arsenite concentration was 1.2±0.3 ng m^–3 (minimum 0.3 ng m^–3, maximum 1.8 ng m^–3). The mean arsenate concentration was 10.4±1.8 ng m^–3, with greater monthly variations than arsenite (minimum 2.1 ng m^–3, maximum 30.6 ng m^–3). The high level of arsenic species in the TSP samples can be related to a copper smelter located in the region.     

Separation of cerium and europium by extraction with tributyl phosphate and di(2-ethylhexyl)phosphoric acid in n-alkane from nitrate solutions

The following extraction systems have been studied: (Ce³⁺+Eu³⁺) (NO₃)-(EDTA, DCTA, DTPA)/TBP in n-alkane and (Ce³⁺+Eu³⁺)(NO₃)/DEHPA in n-alkane at concentration ratios as follows: [Ce³⁺]=trace –1 mol·dm^–3, [Eu³⁺]=trace –0.1 mol·dm^–3. [TBP]=(0.183–1.83) mol·dm^–3, [DEHPA]=(5·10^–3–0.1) mol·dm^–3, [(H, Na)NO₃]=(0.1–6) mol·dm^–3, [Eu³⁺]: [EDTA, DCTA, DTPA]=11–110. The initial concentration of Eu³⁺ in aqueous phase in the extraction system containing a mixture of Ce³⁺ and Eu³⁺ was trace, 1% and 10% compared with the Ce³⁺ concentration. The distribution of the elements between the phases was observed radiometrically using¹⁴¹Ce,¹⁵²Eu and¹⁵⁴Eu. The results are documented by the distribution ratios D_Ce, D_Eu and separation factor =D_Eu/D_Ce as functions of variable parameters of the systems.     

Simultaneous determination of gibberellic acid, indole-3-acetic acid and abscisic acid in wheat extracts by solid-phase extraction and liquid chromatography-electrospray tandem mass spectrometry

A liquid chromatography–tandem mass spectrometry (LC–MS/MS) method was developed for simultaneous determination of three representative phytohormones in plant samples: gibberellic acid (GA₃), indole-3-acetic acid (IAA) and abscisic acid (ABA). A solid-phase extraction (SPE) pretreatment method was used to concentrate and purify the three phytohormones of different groups from plant samples. The separation was carried out on a C₁₈ reversed-phase column, using methanol/water containing 0.2% formic acid (50:50, v/v) as the isocratic mobile phase at the flow-rate of 1.0 mL min⁻¹, and the three phytohormones were eluted within 7 min. A linear ion trap mass spectrometer equipped with electrospray ionization source was operated in negative ion mode. Selective reaction monitoring (SRM) was employed for quantitative measurement. The SRM transitions monitored were as 345 → 239, 301 for GA₃, 174 → 130 for IAA and 263 → 153, 219 for ABA. Good linearities were found within the ranges of 5–200 μg mL⁻¹ for IAA and 0.005–10 μg mL⁻¹ for ABA and GA₃. Their detection limits based on a signal-to-noise ratio of three were 0.005 μg mL⁻¹, 2.2 μg mL⁻¹ and 0.003 μg mL⁻¹ for GA₃, IAA and ABA, respectively. Good recoveries from 95.5% to 102.4% for the three phytohormones were obtained. The results demonstrated that the SPE-LC–MS/MS method developed is highly effective for analyzing trace amounts of the three phytohormones in plant samples.     

Sorption of nickel on marl

Batch sorption experiments using nickel have been carried out on marl, a sedimentary, carbonaceous rock. All experiments were performed with a synthetic water of pH 7.3 and in an atmosphere of N₂/1% CO₂. Over the equilibrium nickel concentration range of 10^–11–10^–5M, sorption was linear and reversible with R_d of 819 ml g^–1. Owing to the linear sorption behavior, R_d was independent of rock/water ratio (r/w=1/5–1/100). The data suggested that at [Ni] lower than 10^–7M an isotope exchange mechanism operated, whereas at higher [Ni], sorption involved ion exchange. Sorption experiments on some of the components of marl indicated that nickel adsorbs mainly on the clay minerals and on the trace of iron hydroxide present; sorption on calcite and quartz was low.     

The structure and dynamic properties of mixed adsorption and penetration layers of α-dipalmitoylphosphatidylcholine/β-lactoglobulin at water/fluid interfaces

The interfacial tensions of mixed α-dipalmitoylphosphatidylcholine (DPPC)/β-lactoglobulin layers at the chloroform/water interface have been measured by the pendent drop and drop volume techniques. In certain intervals, the adsorption kinetics of these mixed layers was strongly influenced by the concentrations of both protein and DPPC. However, at low protein concentration, C_{β-lactoglobulin}=0.1 mg l⁻¹, the adsorption rate of mixed interfacial layers was mainly controlled by the variation of the DPPC concentration. As C_{β-lactoglobulin} was increased to 0.8 mg l⁻¹, the interfacial activity was abruptly increased, and within the concentration range of C_DPPC=10⁻⁴–10⁻⁵ mol l⁻¹, the DPPC has very little effect on the whole adsorption process. In this case, the adsorption rate of mixed layers was mainly dominated by the protein adsorption. This phenomenon also happened as the protein concentration was further increased to 3.6 mg l⁻¹. When C_DPPC>3 · 10^–5 mol l⁻¹, the adsorption behaviour was very similar to that of the pure DPPC although the protein concentration was changed. The equilibrium interfacial tensions of the mixed layers are dramatically effected by the lipid as compared to the pure protein adsorption at the same concentration. It reveals the estimation of which composition of lipid and protein decreases the interfacial tension. The combination of Brewster angle microscopy (BAM) with a conventional LB trough was applied to investigate the morphology of the mixed DPPC/β-lactoglobulin layers at the air/water interface. The mixed insoluble monolayers were produced by spreading the lipid at the water surface and the protein adsorbed from the aqueous buffer subphase. The BAM images allow to visualise the protein penetration and distribution into the DPPC monolayer on compression of the complex film. It is shown that a homogeneous distribution of β-lactoglobulin in lipid layers preferentially happens in the liquid fluid state of the monolayer while the protein can be squeezed out at higher surface pressures.     

Extraction chromatographic behaviour of Am/IV/ in the system: H2SO4-K10P2W17O61-Primene JMT

The extraction chromatographic separation of Am/IV/ and Cm/III/ in the H₂SO₄-K₁₀P₂W₁₇O₆₁-Primene JMT system was studied. The elaborated method permitted to purify effectively americium. The yield of americium at an initial concentration of 10^–3M is about 93–95%, the curium content does not exceed 0.1% of the initial concentration.     

Preparation and properties of compact cubic δ-NbN1−x

Compact -NbN_1–x was prepared by heating niobium wire for several days in nitrogen at 4 MPa pressure and temperatures of 1 723 to 1 923 K. The samples obtained had compositions between NbN_0.924 and NbN_0.975±0.002 and were coarse-grained. The lattice parameter increases with the nitrogen content froma=0.43884 nm for NbN_0.924 toa=0.43913 nm for NbN_0.975. From the determination of the lattice parameters up to 1 073 K the coefficient of linear thermal expansion as a function of temperature was evaluated. The microhardness HV_0.1 decreases from 1 300±80·10⁷Nm^–2 for NbN_0.924 to 1080±60·10⁷ Nm^–2 for NbN_0.975. The occupancies of both the niobium and the nitrogen sublattices were calculated using experimental density data. The occupancy of the niobium sublattice decreases linearly with increasing nitrogen content. An extrapolation gives 2.9±0.4% vacancies in both sublattices for stoichiometric -NbN.

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Herstellung und Eigenschaften von kompaktem, kubischem -NbN_1–x

Zusammenfassung Kompaktes -NbN_1–x wurde durch mehrtägiges Erhitzen von Niobdraht in Stickstoff bei einem Druck von 4 MPa und Temperaturen von 1 273 bis 1 923 K hergestellt. Die dabei erhaltenen Proben hatten Zusammensetzungen von NbN_0.924 bis NbN_0.975±0.002 und zeigten ein grobkörniges Gefüge. Der Gitterparameter steigt mit dem Stickstoffgehalt vona=0.43884 nm für NbN_0.924 bisa=0.43913 nm für NbN_0.975 an. Von einer Bestimmung der Gitterparameter bis 1 073 K wurde der lineare thermische Ausdehnungskoeffizient erhalten. Die Mikrohärte HV_0.1 sinkt von 1 300±80·10⁷ Nm^–2 für NbN_0.924 auf 1 080±60·10⁷ Nm^–2 für NbN_0.975 ab. Die Besetzung sowohl des Niob- als auch des Stickstoffteilgitters wurde unter Verwendung von experimentell gemessenen Dichten bestimmt. Die Besetzung des Niobteilgitters fällt mit zunehmendem Stickstoffanteil linear ab. Eine Extrapolation dieser Werte ergibt für stöchiometrisches -NbN einen Leerstellenanteil von 2.9±0.4% auf beiden Teilgittern.

     

Removal, preconcentration and determination of Mo(VI) from water and wastewater samples using maghemite nanoparticles

Removal and recovery of Mo(VI) from aqueous solutions were investigated using maghemite (γ-Fe₂O₃) nanoparticles. Combination of nanoparticle adsorption and magnetic separation was used to the removal and recovery of Mo(VI) from water and wastewater solutions. The nanoscale maghemite with mean diameter of 50 nm was synthesized by reduction coprecipitation method followed by aeration oxidation. Various factors influencing the adsorption of Mo(VI), e.g. pH, temperature, initial concentration, and coexisting common ions were studied. Adsorption reached equilibrium within <10 min and was independent of initial concentration of Mo(VI). Studies were performed at different pH values to find out the pH at which maximum adsorption occurred. The maximum adsorption occurred at pHs between 4.0 and 6.0. The Langmuir adsorption capacity (q_max) was found to be 33.4 mg Mo(VI)/g of the adsorbent. The results showed that nanoparticle (γ-Fe₂O₃) is suitable for the removal of Mo(VI), as molybdate, from water and wastewater samples. The adsorbed Mo(VI) was then desorbed and determined spectrophotometrically using bromopyrogallol red as a complexation reagent. This allows the determination of Mo(VI) in the range 1.0–86.0 ng mL⁻¹.     

Redox-iodometry: a new potentiometric method

A new iodometric method for quantifying aqueous solutions of iodide-oxidizing and iodine-reducing substances, as well as plain iodine/iodide solutions, is presented. It is based on the redox potential of said solutions after reaction with iodide (or iodine) of known initial concentration. Calibration of the system and calculations of unknown concentrations was performed on the basis of developed algorithms and simple GWBASIC-programs. The method is distinguished by a short analysis time (2–3 min) and a simple instrumentation consisting of pH/mV meter, platinum and reference electrodes. In general the feasible concentration range encompasses 0.1 to 10^–6 mol/L, although it goes down to 10^–8 mol/L (0.001 mg Cl₂/L) for oxidants like active chlorine compounds. The calculated imprecision and inaccuracy of the method were found to be 0.4–0.9% and 0.3–0.8%, respectively, resulting in a total error of 0.5–1.2%. Based on the experiments, average imprecisions of 1.0–1.5% at c(Ox)>10^–5 M, 1.5–3% at 10^–5 to 10^–7 M, and 4–7% at <10^–7 M were found. Redox-iodometry is a simple, precise, and time-saving substitute for the more laborious and expensive iodometric titration method, which, like other well-established colorimetric procedures, is clearly outbalanced at low concentrations; this underlines the practical importance of redox-iodometry.

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An erratum to this article is available at .     

Preparation of uniformly sized alginate microspheres using the novel combined methods of microchannel emulsification and external gelation

The purpose of this study was to prepare alginate (ALG) microspheres with narrow size distribution using a combination of microchannel (MC) emulsification technique and external gelation method. ALG solution was dispersed as water-in-oil (W/O) emulsion droplets in iso-octane containing 5 wt% Span 85 as the immiscible continuous phase via MC emulsification technique using hydrophobic MC array. The MC array used in this experiment is a grooved-type MC consisting of 1070 channels fabricated on a 25 mm × 28 mm silicon microchip. The monodisperse W/O emulsion droplets generated from the MCs were in the mean particle diameter (d_av) range of 18–22 μm and coefficient of variation (CV) of 5–26% at the ALG concentrations of 0.5–3.0 wt% and flow rates of 0.05–0.4 mL/h. The d_av of the emulsion droplets hardly changed below a dispersed phase threshold flow rate of 0.2 mL/h but gradually became smaller when the dispersed phase concentration was increased. The resulting emulsion droplets were then congealed to form rigid ALG gel particles by reacting them with calcium chloride (CaCl₂) solution. Gelation of the ALG droplets by calcium ion (Ca²⁺) resulted in shrinkage of its d_av, forming uniformly sized ALG microspheres with an average diameter of 6.2 μm and a CV of below 10% at the ALG concentration of 3 wt%.     

Development of a sensitive thermal desorption method for the determination of trihalomethanes in humid ambient and alveolar air

A sensitive and reliable method has been developed for the determination of trihalomethanes (THMs) in air samples through adsorption in sorbent tubes and thermal desorption (TD) of the compounds, followed by gas chromatography (GC)–mass spectrometry (MS) analysis. Three commercial sorbent materials were compared in terms of adsorption efficiency and breakthrough volume, finding Chromosorb 102 to be the most appropriate adsorbent for air sampling. The method allows us to reach detection limits of 0.03 ng (0.01 μg m⁻³ for 3 l of air), linear ranges from 0.1 to 2000 ng and specific uncertainties of ca. 5.0 ± 0.2 ng for all THMs. Several salts were tested to reduce water retention (from the humid air of an indoor swimming pool) at the sampling stage, Na₂SO₄ being the one that provides optimum efficiency. The method was validated by a new recovery study in which several tubes with and without adsorbent were spiked with THMs and analyzed by TD-GC/MS, recoveries ranging from 92% to 97% for all the compounds. Finally, the performance of the method was evaluated through the analysis of ambient air samples from an indoor swimming pool and alveolar air samples from swimmers to assess their THM uptake. THMs were found to be stable in the sorbent tubes for at least 1 month when stored at 4 °C.     

Rapid concentrating of radiostrontium from model fallout,drinking and technological water,using solvent extraction with cobalt dicarbollide and Slovafol 909

The optimum concentration of the extractants for rapid radiostrontium concentration is 0.1M HB (chlorinated cobalt dicarbollide acid) and 1.5% vol. of Slovafol 909 in a mixture of CCl₄(40%) and nitrobenzene. The recommended initial carrier concentration is 2·10^–4 M Sr, initial aq. pH4.3, time of shaking 3 min. Yield in the range 80–97% can be achieved in rapidly concentrating Sr from 1 dm³ aqueous phase into 10–20 ml of the extract. The yield decreases with increasing Ca concentration in the model water. The time needed for the concentrating does not exceed 30 min.     

Mechanism and kinetics of crystallization of α-Fe in amorphous Fe81B13Si4C2 alloy

The non-isothermal crystallization of α-Fe from Fe₈₁B₁₃Si₄C₂ amorphous alloy was investigated. The kinetic parameters of crystallization process were determined by Kissinger and Kissinger–Akahira–Sunose (KAS) methods. It was established that the kinetic parameters of transformation do not change with the degree of crystallization in the range of 0.1–0.7. The kinetic model of the crystallization process was determined using the Malek's procedure. It was established that the primary crystallization α-Fe phase from amorphous alloy can be described by Šesták–Berggren autocatalytic model with kinetic triplet E_a = 349.4.0 kJ mol⁻¹, ln A = 50.76 and f(α) = α^0.72(1 − α)^1.02.     

Electroless Pd and Ag deposition kinetics of the composite Pd and Pd/Ag membranes synthesized from agitated plating baths

The atomic absorption spectroscopy (AAS) has been successfully utilized for the measurement of the Pd and Ag ion concentrations in the plating baths and to elucidate the effects of temperature, initial metal ion and reducing agent concentrations and agitation on the electroless plating kinetics of Pd and Ag metals. The initial metal ion concentrations for Pd and Ag were varied over a range of 8.2–24.5 mM and 3.1–12.5 mM, respectively. The plating reactions were conducted in a constant temperature electroless plating bath over a temperature range of 20–60 °C and an initial hydrazine concentration range of 1.8–5.4 mM. It was found that the electroless plating of both Pd and Ag were strongly affected by the external mass transfer in the absence of bath agitation. The external mass transfer limitations for both Pd and Ag deposition have been minimized at or above an agitation rate of 400 rpm, resulting in a maximum conversion of the plating reaction at 60 °C and dramatically shortened plating times with the added advantage of uniform deposition morphology. The derivation of the differential rate laws and the estimation of the reaction orders and the activation energies for the electroless Pd and Ag kinetics were conducted via non-linear regression analysis based on the method of initial rates. For a constant-volume batch reactor, the integrated rate law was solved to calculate the conversion and the reactant concentrations as a function of plating time. The model fits were in good agreement with the experimental data. Furthermore, the bath agitation and the plating conditions used in the kinetics study were adopted for the synthesis of 16–20 μm thick composite Pd/Ag membranes (10–12 wt% Ag) and a pure-Pd membrane with a hydrogen selective dense Pd layer as thin as 4.7 μm. While hydrogen permeance of the Pd/Ag membranes A and B at 450 °C were 28 and 32 m³/m²-h-atm^0.5, the H₂ permeance for the 4.7 μm thick pure-Pd membrane at 400 °C was as high as 63 m³/m²-h-atm^0.5_. The long-term permeance testing of all the membranes synthesized from agitated plating baths resulted in a relatively slow leak growth due primarily to the improved morphology obtained via the bath agitation and modified plating conditions.     

Bulk-modified modified screen-printing carbon electrodes with both lactate oxidase (LOD) and horseradish peroxide (HRP) for the determination of L-lactate in flow injection analysis mode

A screen-printed carbon electrode modified with both HRP and LOD (SPCE–HRP/LOD) has been developed for the determination of l-lactate concentration in real samples. The resulting SPCE–HRP/LOD was prepared in a one-step procedure, and was then optimised as an amperometric biosensor operating at [0, −100] mV versus Ag/AgCl for l-lactate determination in flow injection mode. A significant improvement in the reproducibility (coefficient variation of about 10%) of the preparation of the biosensors was obtained when graphite powder was modified with LOD in the presence of HRP previously oxidised by periodate ion (IO₄⁻). Optimisation studies were performed by examining the effects of LOD loading, periodation step and rate of the binder on analytical performances of SPCE–HRP/LOD. The sensitivity of the optimised SPCE–HRP/LOD to l-lactate was 0.84 nA L μmol⁻¹ in a detection range between 10 and 180 μMol. The possibility of using the developed biosensor to determine l-lactate concentrations in various dairy products was also evaluated.