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Analytica Chimica Acta (v.754, #)
Universal nucleic acid sequence-based amplification for simultaneous amplification of messengerRNAs and microRNAs by Andreas Mader; Ulrike Riehle; Thomas Brandstetter; Elmar Stickeler; Juergen Ruehe (pp. 1-7).
Display Omitted► We have expanded the NASBA method to boost its multiplex capacity. ► We report on multiplex miRNA amplification and detection based on NASBA and custom-made microarrays. ► The reported method allows parallel analysis of multiple miRNA and mRNA sequences.A universal NASBA assay is presented for simultaneous amplification of multiple microRNA (miRNA) and messengerRNA (mRNA) sequences. First, miRNA and mRNA sequences are reverse transcribed using tailed reverse transcription primer pairs containing a gene-specific and an non-specific region. For reverse transcription of small miRNA molecules a non-specific region is incorporated into a structured stem-loop reverse transcription primer. Second, a universal NASBA primer pair that recognizes the tagged cDNA molecules enables a simultaneous, transcription-based amplification reaction (NASBA) of all different cDNA molecules in one reaction. The NASBA products (RNA copies) are detected by gene-specific DNA probes immobilized on a biochip. By using the multiplex reverse transcription combined with the universal NASBA amplification up to 14 different mRNA and miRNA sequences can be specifically amplified and detected in parallel. In comparison with standard multiplex NASBA assays this approach strongly enhances the multiplex capacity of NASBA-based amplification reactions. Furthermore simultaneous assaying of different RNA classes can be achieved that might be beneficial for studying miRNA-based regulation of gene expression or for RNA-based tumor diagnostics.
Keywords: microRNA; Multiplex; Isothermal amplification; NASBA; Microarray
Adaptive approach for variable noise suppression on laser-induced breakdown spectroscopy responses using stationary wavelet transform by Jan Schlenke; Lars Hildebrand; Javier Moros; J. Javier Laserna (pp. 8-19).
Display Omitted► A noise reduction technique for LIBS signals using wavelet transform is presented. ► Variable thresholding eliminates undesired artifacts from single spectrum. ► Proposed approach offers superior signal preservation than other alternatives. ► Single emission lines are rarely deteriorated by more than 3% after denoising.Spectral signals are often corrupted by noise during their acquisition and transmission. Signal processing refers to a variety of operations that can be carried out on measurements in order to enhance the quality of information. In this sense, signal denoising is used to reduce noise distortions while keeping alterations of the important signal features to a minimum. The minimization of noise is a highly critical task since, in many cases, there is no prior knowledge of the signal or of the noise. In the context of denoising, wavelet transformation has become a valuable tool. The present paper proposes a noise reduction technique for suppressing noise in laser-induced breakdown spectroscopy (LIBS) signals using wavelet transform. An extension of the Donoho's scheme, which uses a redundant form of wavelet transformation and an adaptive threshold estimation method, is suggested. Capabilities and results achieved on denoising processes of artificial signals and actual spectroscopic data, both corrupted by noise with changing intensities, are presented. In order to better consolidate the gains so far achieved by the proposed strategy, a comparison with alternative approaches, as well as with traditional techniques, is also made.
Keywords: Automatic de-noising; Wavelet transformation; Shift invariant; Thresholding; LIBS
Optimization of headspace experimental factors to determine chlorophenols in water by means of headspace solid-phase microextraction and gas chromatography coupled with mass spectrometry and parallel factor analysis by Rocío Morales; M. Cruz Ortiz; Luis A. Sarabia (pp. 20-30).
Display Omitted► D-optimal design allows the reduction of experiments from 48 to 18 maintaining the precision. ► A procedure based on HS-SPME–GC/MS to determine chlorophenols, below ppt units, has been used. ► HS-SPME–GC/MS has been used to analyze four chlorophenols in river water samples. ► Decision limits, from 39 to 208ngL−1, has been obtained with a false positive probability fixed at 5%. ► Unequivocally identification of chlorophenols was verified after taking place the PARAFAC decomposition.In this work an analytical procedure based on headspace solid-phase microextraction and gas chromatography coupled with mass spectrometry (HS-SPME–GC/MS) is proposed to determine chlorophenols with prior derivatization step to improve analyte volatility and therefore the decision limit (CCα). After optimization, the analytical procedure was applied to analyze river water samples. The following analytes are studied: 2,4-dichlorophenol (2,4-DCP), 2,4,6-trichlorophenol (2,4,6-TrCP), 2,3,4,6-tetrachlorophenol (2,4,6-TeCP) and pentachlorophenol (PCP). A D-optimal design is used to study the parameters affecting the HS-SPME process and the derivatization step. Four experimental factors at two levels and one factor at three levels were considered: (i) equilibrium/extraction temperature, (ii) extraction time, (iii) sample volume, (iv) agitation time and (v) equilibrium time. In addition two interactions between four of them were considered. The D-optimal design enables the reduction of the number of experiments from 48 to 18 while maintaining enough precision in the estimation of the effects. As every analysis took 1h, the design is blocked in 2 days.The second-order property of the PARAFAC (parallel factor analysis) decomposition avoids the need of fitting a new calibration model each time that the experimental conditions change. In consequence, the standardized loadings in the sample mode estimated by a PARAFAC decomposition are the response used in the design because they are proportional to the amount of analyte extracted.It has been found that block effect is significant and that 60°C equilibrium temperature together with 25min extraction time are necessary to achieve the best extraction for the chlorophenols analyzed. The other factors and interactions were not significant. After that, a calibration based in a PARAFAC2 decomposition provided the following values of CCα: 120, 208, 86, 39ngL−1 for 2,4-DCP, 2,4,6-TrCP, 2,3,4,5-TeCP and PCP respectively for a probability of false positive set at 5%. Also, the accuracy (trueness and precision) of the procedure is assessed. Finally, river water samples have been analyzed with the proposed method showing the absence of the chlorophenols studied.
Keywords: Chlorophenols; D-optimal design; Parallel factor analysis; River water samples; Headspace solid-phase microextraction; Gas chromatography–mass spectrometry
Combining local wavelength information and ensemble learning to enhance the specificity of class modeling techniques: Identification of food geographical origins and adulteration by Lu Xu; Zi-Hong Ye; Si-Min Yan; Peng-Tao Shi; Hai-Feng Cui; Xian-Shu Fu; Xiao-Ping Yu (pp. 31-38).
The acceptance or rejection of a future object can be explicitly determined by examining its acceptance frequency by sub-models based on local wavelength intervals.Display Omitted► Ensemble of one-class models on separate wavelength sub-intervals was proposed. ► A new object is predicted by examining its acceptance frequency by sub-models. ► A data-driven cross validation is used to control significance level. ► This method can enhance model specificity without feature reduction.Class modeling techniques are required to tackle various one-class problems. Because the training of class models is based on the target class and the origins of future test objects usually cannot be exactly predefined, the criteria for feature selection of class models are not very straightforward. Although feature reduction can be expected to improve class models performance, more features retained can provide a sufficient description of the sought-for class. This paper suggests a strategy to balance class description and model specificity by ensemble learning of sub-models based on separate local wavelength intervals. The acceptance or rejection of a future object can be explicitly determined by examining its acceptance frequency by sub-models. Considering the lack of information about sub-model independence, we propose to use a data-driven method to control the sensitivity of the ensemble model by cross validation. In this way, all the wavelength intervals are used for class description and the local wavelength intervals are highlighted to enhance the ability to detect out-of-class objects.The proposed strategy was performed on one-class partial least squares (OCPLS) and soft independent modeling of class analogy (SIMCA). By analysis of two infrared spectral data sets, one for geographical origin identification of white tea and the other for discrimination of adulterations in pure sesame oil, the proposed ensemble class modeling method was demonstrated to have similar sensitivity and better specificity compared with total-spectrum SIMCA and OCPLS models. The results indicate local spectral information can be extracted to enhance class model specificity.
Keywords: Ensemble class models; Spectral interval selection; Soft independent modeling of class analogy; One-class partial least squares; Infrared spectroscopy
On the construction of experimental designs for a given task by jointly optimizing several quality criteria: Pareto-optimal experimental designs by M.S. Sánchez; L.A. Sarabia; M.C. Ortiz (pp. 39-46).
Display Omitted► A methodological approach to compute Pareto-optimal experimental designs. ► Pareto-optimal designs are a useful tool in quality by design (Q&D). ► A family of optimal designs is computed by jointly handling several quality criteria. ► Ad hoc experimental designs are computed for a given number of experiments, domain, and model. ► Using genetic algorithms allows the search in both discrete and continuous spaces.Experimental designs for a given task should be selected on the base of the problem being solved and of some criteria that measure their quality. There are several such criteria because there are several aspects to be taken into account when making a choice. The most used criteria are probably the so-called alphabetical optimality criteria (for example, the A-, E-, and D-criteria related to the joint estimation of the coefficients, or the I- and G-criteria related to the prediction variance). Selecting a proper design to solve a problem implies finding a balance among these several criteria that measure the performance of the design in different aspects. Technically this is a problem of multi-criteria optimization, which can be tackled from different views.The approach presented here addresses the problem in its real vector nature, so that ad hoc experimental designs are generated with an algorithm based on evolutionary algorithms to find the Pareto-optimal front. There is not theoretical limit to the number of criteria that can be studied and, contrary to other approaches, no just one experimental design is computed but a set of experimental designs all of them with the property of being Pareto-optimal in the criteria needed by the user. Besides, the use of an evolutionary algorithm makes it possible to search in both continuous and discrete domains and avoid the need of having a set of candidate points, usual in exchange algorithms.
Keywords: Experimental design; Design optimality; Multicriteria optimization; Pareto-optimal front; Evolutionary algorithms
Determination of chemical oxygen demand of nitrogenous organic compounds in wastewater using synergetic photoelectrocatalytic oxidation effect at TiO2 nanostructured electrode by Lihong Li; Shanqing Zhang; Guiying Li; Huijun Zhao (pp. 47-53).
Display Omitted► A synergetic photoelectrocatalytic oxidation effect is observed at TiO2 photoanodes. ► It assists the mineralization of nitrogenous organic compounds (NOCs). ► It facilitates the accurate measurement of COD of the NOCs-containing wastewater.Chemical oxygen demand (COD) is one of the most important parameters in water quality assessment and monitoring. The natural degradation of nitrogenous organic compounds (NOCs) in water requires significant amounts of oxygen. In the determination of standard COD however, NOCs are persistent compounds that cannot be completely oxidized even in the most oxidative chemical environments, i.e. the reaction media that contain high concentrations of dichromate in strong acid at high temperature. Consequently, the measured COD values of wastewater samples containing NOCs are commonly lower than theoretical COD values and do not reflect the actual oxygen demand of the water body. This problem is partially alleviated when the photoelectrochemical method for COD determination (PeCOD) based on nanostructured TiO2 photoanode is utilized. To completely overcome this problem, a synergetic photoelectrochemical oxidation effect in thin layer cells is used to achieve complete oxidation of NOCs. This is done by the simple addition of a hydroxyl organic compound (i.e. glucose) into the test sample before the PeCOD measurement. Preliminary experimental results demonstrate that the synergetic PeCOD method provides an effective and reliable means to measure COD values of NOC-containing pollutants without the need for toxic or expensive reagents.
Keywords: Chemical oxygen demand; Synergetic oxidation; Photoelectrocatalysis; TiO; 2; Nitrogenous organic compounds
Determination of ammonium in aqueous samples using new headspace dynamic in-syringe liquid-phase microextraction with in situ derivitazation coupled with liquid chromatography–fluorescence detection by Sarangapani Muniraj; Cheing-Tong Yan; Hou-Kung Shih; Vinoth Kumar Ponnusamy; Jen-Fon Jen (pp. 54-60).
Display Omitted► Novel headspace dynamic in-syringe liquid-phase derivatization/extraction method.► Fast, sensitive and selective analysis of ammonium in water sample was achieved.► Simple, low cost, efficient and automated sampling procedure to determine ammonia.A new simultaneous derivatization and extraction method for the preconcentration of ammonia using new one-step headspace dynamic in-syringe liquid-phase microextraction with in situ derivatization was developed for the trace determination of ammonium in aqueous samples by liquid chromatography with fluorescence detection (LC–FLD). The acceptor phase (as derivatization reagent) containing o-phthaldehyde and sodium sulfite was held within a syringe barrel and immersed in the headspace of sample container. The gaseous ammonia from the alkalized aqueous sample formed a stable isoindole derivative with the acceptor phase inside the syringe barrel through the reciprocated movements of plunger. After derivatization-cum-extraction, the acceptor phase was directly injected into LC–FLD for analysis. Parameters affecting the ammonia evolution and the extraction/derivatization efficiency such as sample matrix, pH, temperature, sampling time, and the composition of derivatization reagent, reaction temperature, and frequency of reciprocated plunger, were studied thoroughly. Results indicated that the maximum extraction efficiency was obtained by using 100μL derivatization reagent in a 1-mL gastight syringe under 8 reciprocated movements of plunger per min to extract ammonia evolved from a 20mL alkalized aqueous solution at 70°C (preheated 4min) with 380rpm stirring for 8min. The detection was linear in the concentration range of 0.625–10μM with the correlation coefficient of 0.9967 and detection limit of 0.33μM (5.6ngmL−1) based on SN−1=3. The method was applied successfully to determine ammonium in real water samples without any prior cleanup of the samples, and has been proved to be a simple, sensitive, efficient and cost-effective procedure for trace ammonium determination in aqueous samples.
Keywords: Headspace; Dynamic in-syringe liquid-phase microextraction; In situ derivatization; Ammonium; Liquid chromatography; Fluorometric detector; Water
pH-controlled dispersive liquid–liquid microextraction for the analysis of ionisable compounds in complex matrices: Case study of ochratoxin A in cereals by Luca Campone; Anna Lisa Piccinelli; Rita Celano; Luca Rastrelli (pp. 61-66).
Display Omitted► A new and selective extraction technique, pH-controlled DLLME, was developed. ► pH-DLLME is able to analyse OTA in cereals without additional sample pretreatment. ► pH-DLLME is a suitable technique for a wide range of ionisable compounds. ► Additional advantages are a higher selectivity and a wider range of application.A new sample preparation procedure, termed pH-controlled dispersive liquid–liquid microextraction (pH-DLLME), has been developed for the analysis of ionisable compounds in highly complex matrices. This DLLME mode, intended to improve the selectivity and to expand the application range of DLLME, is based on two successive DLLMEs conducted at opposite pH values. pH-DLLME was applied to determination of ochratoxin A (OTA) in cereals. The hydrophobic matrix interferences in the raw methanol extract (disperser, 1mL) were removed by a first DLLME (I DLLME) performed at pH 8 to reduce the solubility of OTA in the extractant (CCl4, 400μL). The pH of the aqueous phase was then adjusted to 2, and the analyte was extracted and concentrated by a second DLLME (extractant, 150μL C2H4Br2). The main factors influencing the efficiency of pH-DLLME including type and volume of I DLLME extractant, as well as the parameters affecting the OTA extraction by II DLLME, were studied in detail. Under optimum conditions, the method has detection and quantification limits of 0.019 and 0.062μgkg−1, respectively, with OTA recoveries in the range of 81.2–90.1% ( n=3). The accuracy of the analytical procedure, evaluated with a reference material (cereal naturally contaminated with OTA), is acceptable (accuracy of 85.6%±1.7, n=5).The applicability of pH-DLLME to the selective extraction of other ionisable compounds, such as acidic and basic pharmaceutical products was also demonstrated.The additional advantages of pH-DLLME are a higher selectivity and the extension of this microextraction technique to highly complex matrices.
Keywords: pH controlled DLLME; Ochratoxin A; HPLC-FLD; Cereal; Sample preparation
Online trapping and enrichment ultra performance liquid chromatography–tandem mass spectrometry method for sensitive measurement of “arginine-asymmetric dimethylarginine cycle” biomarkers in human exhaled breath condensate by Iole Maria Di Gangi; Paola Pirillo; Silvia Carraro; Antonina Gucciardi; Mauro Naturale; Eugenio Baraldi; Giuseppe Giordano (pp. 67-74).
Display Omitted► Simultaneous quantification of “arginine-ADMA cycle” metabolites developed in EBC. ► EBC is a non-invasive matrix highly useful in patients with respiratory diseases. ► Method, fast, precise and accurate, is suitable in the pediatric clinical studies. ► Sensitivity is increased using on-line trapping and enrichment-UPLC–MS/MS method. ► EBC measurements in asthmatic adolescents confirm that ADMA is increased in asthma.Exhaled breath condensate (EBC) is a biofluid collected non invasively that, enabling the measurement of several biomarkers, has proven useful in the study of airway inflammatory diseases, including asthma, COPD and cystic fibrosis. To the best of our knowledge, there is no previous report of any analytical method to detect ADMA in EBC.Aim of this work was to develop an online sample trapping and enrichment system, coupled with an UPLC–MS/MS method, for simultaneous quantification of seven metabolites related to “Arginine-ADMA cycle”, using the isotopic dilution.Butylated EBC samples were trapped in an online cartridge, washed before and after each injection with cleanup solution to remove matrix components and switched inline into the high pressure analytical column. Multiple reaction monitoring in positive mode was used for analyte quantification by tandem mass spectrometry.Validation studies were performed in EBC to examine accuracy, precision and robustness of the method. For each compound, the calibration curves showed a coefficient of correlation ( r2) greater than 0.992. Accuracy (%Bias) was <3% except for NMMA and H-Arg (<20%), intra- and inter-assay precision (expressed as CV%) were within ±20% and recovery ranged from 97.1 to 102.8% for all analytes.Inter-day variability analysis on 20 EBC of adult subjects did not demonstrate any significant variation of quantitative data for each metabolite. ADMA and SDMA mean concentrations (μmolL−1), measured in EBC samples of asthmatic adolescents are significantly increased ( p<0.0001) than in normal controls (0.0040±0.0021 vs. 0.0012±0.0005 and 0.0020±0.0015 vs. 0.0002±0.0001, respectively), as well the ADMA/Tyr (0.34±0.09 vs. 0.12±0.02, p<0.0001) and the SDMA/Tyr ratio (0.10±0.04 vs. 0.015±0.004, p<0.0001).The proposed method features simple specimen preparation, maintenance of an excellent peak shape of all metabolites and reduced matrix effects as well mass spectrometer noise. Moreover, the possibility to perform different cycles of enrichment, using large injection volumes, compensated for the low concentration of analytes contained in EBC, leading to a good analytical sensitivity. Preliminary data obtained from asthmatic and healthy adolescents, demonstrated that the analytical method applied to EBC seems suitable not only for research purposes, but also for clinical routinely analysis.
Keywords: ADMA; NOS; “Arginine-ADMA cycle”; Exhaled breath condensate (EBC); Tandem mass spectrometryAbbreviations; EBC; exhaled breath condensate; UPLC–MS/MS; ultra-performance liquid chromatography–tandem mass spectrometry; ICS; inhaled corticosteroids; NOS; nitric oxide synthase; COPD; chronic obstructive pulmonary disease
Development of a new multi-residue laser diode thermal desorption atmospheric pressure chemical ionization tandem mass spectrometry method for the detection and quantification of pesticides and pharmaceuticals in wastewater samples by Michel Boisvert; Paul B. Fayad; Sébastien Sauvé (pp. 75-82).
Display Omitted► We analyzed emerging contaminants of varied origins. ► We used a single mixed-mode solid phase extraction protocol for all analytes. ► We analyzed the samples in <15s using an ultrafast LDTD-APCI-MS/MS method. ► Recoveries of target compounds were from 76% to 106%. ► Limits of detection were from 30 to 122ngL−1.A new solid phase extraction (SPE) method coupled to a high throughput sample analysis technique was developed for the simultaneous determination of nine selected emerging contaminants in wastewater (atrazine, desethylatrazine, 17β-estradiol, ethynylestradiol, norethindrone, caffeine, carbamazepine, diclofenac and sulfamethoxazole). We specifically included pharmaceutical compounds from multiple therapeutic classes, as well as pesticides. Sample pre-concentration and clean-up was performed using a mixed-mode SPE cartridge (Strata ABW) having both cation and anion exchange properties, followed by analysis by laser diode thermal desorption atmospheric pressure chemical ionization coupled to tandem mass spectrometry (LDTD-APCI-MS/MS). The LDTD interface is a new high-throughput sample introduction method, which reduces total analysis time to less than 15s per sample as compared to minutes with traditional liquid-chromatography coupled to tandem mass spectrometry (LC–MS/MS). Several SPE parameters were evaluated in order to optimize recovery efficiencies when extracting analytes from wastewater, such as the nature of the stationary phase, the loading flow rate, the extraction pH, the volume and composition of the washing solution and the initial sample volume. The method was successfully applied to real wastewater samples from the primary sedimentation tank of a municipal wastewater treatment plant. Recoveries of target compounds from wastewater ranged from 78% to 106%, the limit of detection ranged from 30 to 122ngL−1 while the limit of quantification ranged from 90 to 370ngL−1. Calibration curves in the wastewater matrix showed good linearity ( R2≥0.991) for all target analytes and the intraday and interday coefficient of variation was below 15%, reflecting a good precision.
Keywords: Laser diode thermal desorption atmospheric pressure chemical ionization tandem mass spectrometry; Mixed-mode solid phase extraction; Multi-residue analysis; Wastewater; Emerging contaminants
A potentiometric chiral sensor forl-Phenylalanine based on crosslinked polymethylacrylic acid–polycarbazole hybrid molecularly imprinted polymer by Yu Chen; Lei Chen; Ruilin Bi; Lan Xu; Yan Liu (pp. 83-90).
Display Omitted► We have fabricated a hybrid chiral MIP sensor in one step. ► The electropolymerization begin with a pendant polymer precursor to form MIP. ► The hybrid MIP gives better adhesion for sensitive layer to contact with electrode. ► The adjustable structure of MIP improved the selectivity and stability of sensor. ► The sensor has good sensitivity and highly selectivity forl-Phenylalanine detection.A novel chiral molecularly imprinted polymer (MIP) sensor forl-Phenylalanine has been developed, which is constructed by electrochemically driven cross-linking a pendant polymer precursor, poly[2-( N-carbazolyl)ethyl methacrylate-co-meth-acrylic acid]s (PCEMMAs). In this MIP sensing material, the recognition sites, the insulating polymethylacrylic acid (PMAA), were covalently bonded to the conducting polycarbazole which could be used as signal transfer interface between recognition layer and electrode. The mole ratio of copolymerizing monomers, 2-( N-carbazolyl) ethyl methacrylate:methylacrylic acid (CE:MAA), and the scanning cycles of electropolymerization were adjusted during the preparation of MIP sensing material. The optimized conditions, CE:MAA=3:2 and 20 scanning cycles, were obtained. And then the properties of MIP films were characterized by atomic force microscope (AFM), X-ray photoelectron spectroscopy (XPS) and water contact angle. Open circuit potential–time technique was used to estimate the enantioselectivity of the MIP sensor. The results indicate that the promising sensor preferentially responsesl-Phenylalanine (l-Phe) overd-Phenylalanine (d-Phe) with a selectivity coefficientKDL=5.75×10−4 and the limit of detection (LOD) is 1.37μM, which reveals its good enantioselectivity and sensitivity.
Keywords: Electrochemical cross-linking; Hybrid molecularly imprinted polymer; Potentiometric chiral sensor; l; -Phenylalanine
Electrochemiluminescent disposable cholesterol biosensor based on avidin–biotin assembling with the electroformed luminescent conducting polymer poly(luminol-biotinylated pyrrole) by J. Ballesta-Claver; J. Ametis-Cabello; J. Morales-Sanfrutos; A. Megía-Fernández; M.C. Valencia-Mirón; F. Santoyo-González; L.F. Capitán-Vallvey (pp. 91-98).
Diagram of biosensor preparation.Display Omitted► Development of one-shot SPE biosensor for cholesterol determination. ► Development of new luminol ECL copolymers with good mechanical properties. ► Synthesis of biotinylated pyrroles by click chemistry. ► Well-arranged self-assembled layers offer good biosensor capabilities. ► Fast reagent immobilization using electrodynamics techniques.An electrochemiluminescent cholesterol disposable biosensor has been prepared by the formation of assembled layers on gold screen-printed cells. The detection layer is based on the electro-formation of new luminol copolymers with different synthesized biotinylated pyrroles prepared by click-chemistry, offering a new transduction layer with new electroluminescent properties on biosensors. The electrochemiluminescence (ECL) luminol copolymers are electroformed by cyclic voltammetry (five cycles) at pH 7.0 uses a10−3M biotinylated pyrrole–luminol ratio of 1:10 in PBS buffer. With respect to the recognition layer, cholesterol oxidase was biotinylated by incubation with biotin vinyl sulfone, and immobilized on the copolymer by avidin–biotin interaction. The analytical signal of the biosensor is the ECL enzymatic initial rate working in chronoamperometric mode at 0.5V excitation potential with 10s between pulses at pH 9.5. The disposable device offers a cholesterol linear range from 1.5×10−5M to 8.0×10−4M with a limit of detection of 1.47×10−5M and accuracy of 7.9% for 9.0×10−5M and 14.1% for 2.0×10−4M, ( n=5). Satisfactory results were obtained for cholesterol determination in serum samples compared to a reference procedure.
Keywords: Electrochemiluminescent copolymer; Disposable biosensor; Biotinylated pyrroles; Luminol; Cholesterol determination