Detection limit

About: Detection limit is a research topic. Over the lifetime, 34379 publications have been published within this topic receiving 644817 citations. The topic is also known as: limit of detection & lower detection limit.

Anodic‐Stripping Voltammetric Immunoassay for Ultrasensitive Detection of Low‐Abundance Proteins Using Quantum Dot Aggregated Hollow Microspheres

Abstract: A new anodic-stripping voltammetric immunoassay protocol for detection of IgG1, as a model protein, was designed by using CdS quantum dot (QD) layer-by-layer assembled hollow microspheres (QDHMS) as molecular tags. Initially, monoclonal anti-human IgG1 specific antibodies were anchored on amorphous magnetic beads preferably selective to capture Fab of IgG1 analyte from the sample. For detection, monoclonal anti-human IgG1 (Fc-specific) antibodies were covalently coupled to the synthesized QDHMS. In a sandwich-type immunoassay format, subsequent anodic-stripping voltammetric detection of cadmium released under acidic conditions from the coupled QDs was conducted at an in situ prepared mercury film electrode. The immunoassay combines highly efficient magnetic separation with signal amplification by the multilayered QD labels. The dynamic concentration range spanned from 1.0 fg mL−1 to 1.0 μg mL−1 of IgG1 with a detection limit of 0.1 fg mL−1. The electrochemical immunoassay showed good reproducibility, selectivity, and stability. The analysis of clinical serum specimens revealed good accordance with the results obtained by an enzyme-linked immunosorbent assay method. The new immunoassay is promising for enzyme-free, and cost-effective analysis of low-abundance biomarkers.

An enzymeless electrochemical sensor for the selective determination of creatinine in human urine

Abstract: Determination of creatinine in various biological fluids is useful for evaluation of renal, muscular and thyroid dysfunctions. An enzymeless electrochemical approach for the selective and quantitative recognition of creatinine in human urine has been demonstrated by using a preanodized screen-printed carbon electrode (SPE * ). During a preconcentration step (at 1.8 V versus Ag/AgCl), the formation of a stable carbon–carbon bond between the electro-generated C O of SPE * and the active methylene group of creatinine was identified by XPS. By using the SPE * together with a medium exchange procedure, the creatinine was selectively detected in the window of 0.37–3.6 mM with a slope and regression coefficient of 16.7 μA/mM and 0.998, respectively, by square-wave voltammetry. Ten successive detection of 0.37 mM creatinine showed a relative standard deviation of 3.4%, indicating a detection limit (signal/noise = 3) of 8.6 μM. Real human urine samples were analyzed by this method and compared with the results obtained from the Jaffe reaction procedure.

Fe3O4 and MnO2 assembled on halloysite nanotubes: A highly efficient solid-phase extractant for electrochemical detection of mercury(II) ions

Abstract: In this study, a novel and simple magnetic electrochemical sensing protocol for the sensitive detection of Hg(II) in aqueous media was demonstrated. For this purpose, the halloysite nanotubes-iron oxide–manganese oxide nanocomposite (HNTs-Fe 3 O 4 –MnO 2 ) was successfully synthesized for the first time. The synthesis process involves the deposition of Fe 3 O 4 nanoparticles on the surface of HNTs using a simple chemical precipitation method, subsequent formation of wire-like MnO 2 nanoparticles on the surface of HNTs-Fe 3 O 4 composites by hydrothermal method with potassium permanganate (KMnO 4 ) and ammonium persulfate ((NH 4 ) 2 S 2 O 8 ). The resulting HNTs-Fe 3 O 4 –MnO 2 nanocomposite was suspended in mercury solution and then brought on the surface of a magnetic carbon paste electrode (MCPE). The amount of analyte was detected electrochemically by applying differential pulse voltammetry (DPV). The conditions of extraction and voltammetric determination were studied and optimized. The proposed method exhibited a linear relationship towards Hg(II) concentrations ranging from 0.5 to 150 μg L −1 . The detection limit achieved was 0.2 μg L −1 (3 S b / m ), which is lower than the US Environmental Protection Agency (EPA) standard (2 μg L −1 for drinkable water). The proposed methodology was applied for quantification of Hg(II) in real water samples and good recoveries were obtained from 96.0 to 102.7%.