limit of detection

In this work, a solid phase spectrophotometric method in association with flow injection analysis for formaldehyde determination has been developed with direct measurement of light-absorption in C 18 material. The 3,5-diacetyl-1,4-dihydrolutidine produced from the reaction between ...

A novel stability-indicating reverse phase high performance liquid chromatography method was developed and validated for the simultaneous determination of Celecoxib (CEL) and Diacerein (DIN) and its impurities in capsule dosage form. The method was developed using L1 column with gradient using the mobile phase consist of Solution A (pH = 2.3 buffer) and Solution B (methanol and acetonitrile; 50 : 50, v/v). The eluted compounds were monitored at 255 nm. CEL and DIN were subjected to oxidative, acid, base, hydrolytic, thermal and photolytic stress conditions. The developed method was validated as per International Conference on Harmonisation guidelines with respect to specificity, linearity, limit of detection, limit of quantitation, accuracy, precision and robustness. The limit of quantitation results were ranged from 0.07 to 0.09 µg/mL for CEL impurities and 0.052 to 0.065 µg/mL for DIN impurities. This method is suitable for the estimation of impurities and assay of CEL and DIN in ...

A new, simple and versatile cloud-point extraction (CPE) methodology has been developed for the separation and preconcentration of copper and nickel. The metals in the initial aqueous solution were complexed with 2-(2′-benzothiazolylazo)-5-(N, N-diethyl) ...

In 1997, low-level perchlorate contamination (<50 ng mL -1 or parts per billion) was discovered in the western U.S. Since that time, it has been found in sites scattered around the nation. Although the Environmental Protection Agency has not established a regulation for perchlorate in drinking water, it has placed perchlorate on the contaminant candidate list (CCL) and the unregulated

Manufacture of VAQTATM, an inactivated hepatitis A virus vaccine, includes extensive purification of the intact virus particle to remove endogenous components from the host cell culture lysate as well as compounds introduced in the upstream purification process. Analysis of the final purified hepatitis A virus product by SDS-PAGE prior to inactivation shows that greater than 95% of the protein in the preparation is found in four protein bands, which have been confirmed to be hepatitis A virus capsid proteins VP0, VP1, VP2 and VP3 based on Western blot and mass spectrometry analyses. Validation of the manufacturing process and direct analysis of the final product were used to demonstrate that no other specific host cell-derived components are detected and that process residuals are all below the limits of detection of the assays used. Establishment of a rigorous standard of high purity for this product was pursued to minimize the impact of impurities during clinical development of th...

The principle of corrosion measurement/monitoring by means of tangential film-based radiography is already known. Most of this experience, however, is limited to qualitative determination of internal defects. The ability to reliably measure remaining wall thickness in pipes has not yet been established. The International Atomic Energy Agency has organized a Co-ordinated Research Project bringing together twelve Member States to study “validation of protocols for corrosion and deposits determination in large diameter pipes by radiography”. The general scope of the project covers radiographic measurement of corrosion and deposits in straight and bent large diameter (>160mm) pipes made of carbon or stainless steel corroded/eroded on the outer or inner surfaces with or without insulation. It is expected to define the limits of detection for each radiation source using the tangential method and to explore the double wall technique beyond this limit. Introduction: The International Ato...

The compensation method and other chemometric methods (derivative, orthogonal function and difference spectrophotometry) have been applied to the direct determination of omeprazole, lansoprazole and pantoprazole in their pharmaceutical preparations. The methods have been validated; the limits of detection were found to be 3.3×10−2, 3.0×10−2 and 3.5×10−2 μg ml−1 for the three drugs, respectively. The repeatabililty of the methods were found to be 0.3–0.5%. The linearity ranges were found to be 0.5–3.5 μg ml−1. The proposed methods have been applied to the determination of the three drugs in their grastro-resistant formulations. The difference spectrophotometric (ΔA) method is unaffected by the presence of acid induced degradation products; hence can be used as a stability indicating assay.

The early detection of relapse following primary surgery for non-small-cell lung cancer and the characterization of emerging subclones, which seed metastatic sites, might offer new therapeutic approaches for limiting tumour recurrence. The ability to track the evolutionary dynamics of early-stage lung cancer non-invasively in circulating tumour DNA (ctDNA) has not yet been demonstrated. Here we use a tumour-specific phylogenetic approach to profile the ctDNA of the first 100 TRACERx (Tracking Non-Small-Cell Lung Cancer Evolution Through Therapy (Rx)) study participants, including one patient who was also recruited to the PEACE (Posthumous Evaluation of Advanced Cancer Environment) post-mortem study. We identify independent predictors of ctDNA release and analyse the tumour-volume detection limit. Through blinded profiling of postoperative plasma, we observe evidence of adjuvant chemotherapy resistance and identify patients who are very likely to experience recurrence of their lung c...

Hydroxychloroquine (HCQ) has been shown to disrupt autophagy and sensitize cancer cells to radiation and chemotherapeutic agents. However, the optimal delivery method, dose, and tumor concentrations required for these effects are not known. This is in part due to a lack of sensitive and reproducible analytical methods for HCQ quantitation in small animals. As such, we developed and validated a selective and sensitive liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) method for simultaneous quantitation of hydroxychloroquine and its metabolites in mouse blood and tissues. The chromatographic separation and detection of analytes were achieved on a reversed phase Thermo Aquasil C18 (50×4.6mm, 3μ) column, with gradient elution using 0.2% formic acid and 0.1% formic acid in methanol as mobile phase at a flow rate of 0.5mL/min. Simple protein precipitation was utilized for extraction of analytes from the desired matrix. Analytes were separated and quantitated using MS...

The principle of corrosion measurement/monitoring by means of tangential film-based radiography is already known. Most of this experience, however, is limited to qualitative determination of internal defects. The ability to reliably measure remaining wall thickness in pipes has not yet been established. The International Atomic Energy Agency has organized a Co-ordinated Research Project bringing together twelve Member States to study

The method presented is applicable to the determination of organophosphorus (OP) pesticide residues in vegetable oils. The method performs in a single step an on-column extraction and cleanup of OP pesticide residues by means of a system of three cartridges. A solution of 1 g oil in n-hexane is loaded into an Extrelut-NT3 cartridge (large-pore diatomaceous material). The OP pesticide residues are extracted by eluting the cartridge with 20 mL acetonitrile, which is cleaned up by passing through a silica and a C18 cartridge connected on-line to the Extrelut NT-3 cartridge. A few milligrams of lipid is carried over into the eluate, which after concentration and solvent exchange is directly amenable to determination by gas chromatography (GC) with flame photometric detector with optical filter for phosphorus compounds (FPD-P). Recovery values for 45 OP pesticide residues are reported at two spiking levels. In the lower concentration range tested (0.09–0.60 mg/kg), satisfactory results (...

A fast method was designed for the simultaneous determination of amphetamine (A), methamphetamine (MA), PMA, MDA, MDMA, MDEA and MBDB in urine. The drugs were analysed by LC (ESI)–MS/MS, after a simple liquid–liquid extraction in the presence of the deuterated ...

The HPLC-DAD method was developed to determine morin content in Maclura cochinchinensis Corner heartwood extract. The chromatographic separation was performed using a Hypersil BDS C18 column, isocratic solvent system of 0.5% acetic acid in water:acetonitrile (80:20) with 1.0 mL/min flow rate and detected at 355 nm. The standard curve of morin was linear in the range of 7-905 μg/mL. The method was precise with intra-day relative standard deviation (RSD) of lower than 1% and 2.06% for inter-day RSD. The method accuracy represented by percent recover was 99.58%. The highly efficient HPLC system developed from this study could detect morin contents in M. cochinchinensis heartwood samples collected from various locations in Thailand in the range of 0.74-1.57% w/w. This developed method provided a useful standardization procedure of M. cochincihinesis materials for further application in pharmacy and other commercial developments.

We developed new cycling probe-based real-time PCR and nested real-time PCR assays for the detection of Histoplasma capsulatum that were designed to detect the gene encoding N-acetylated α-linked acidic dipeptidase (NAALADase), which we previously identified as an H. capsulatum antigen reacting with sera from patients with histoplasmosis. Both assays specifically detected the DNAs of all H. capsulatum strains but not those of other fungi or human DNA. The limited of detection (LOD) of the real-time PCR assay was 10 DNA copies when using 10-fold serial dilutions of the standard plasmid DNA and 50 DNA copies when using human serum spiked with standard plasmid DNA. The nested real-time PCR improved the LOD to 5 DNA copies when using human serum spiked with standard plasmid DNA, which represents a 10-fold higher than that observed with the real-time PCR assay. To assess the ability of the two assays to diagnose histoplasmosis, we analyzed a small number of clinical specimens collected f...

In this research characterization and method for determination of CGA in green and roasted coffee beans have been reported by UV-Vis spectroscopy. The optical transition properties and solvent effects of CGA were measured in different polar-solvents. After characterization of the electron transition of the standard solutions, a method was developed for UV-Vis spectrophotometer determination of CGA in coffee beans. The method was resolved (deconvoluted), the overlapped spectra of CGA and caffeine using dichloromethane and a direct determination of CGA from the residue of the extraction, at peak height. The validations of the methods are limit of detection, limit of quantification, linearity, recovery study and precision calculated as coefficients of variation. The obtained results were in excellent agreement with those obtained with HPLC method, verified by the student t-test at 95% confidence level.