Internal Standard an Important Analyte Use in Drug Analysis by Liquid Chromatography Mass Spectrometry- An Article

Internal standard is an external compound which is mixed with targeted analytical solution and matrix as a constant concentration and use for preparing calibration standard curve by using ratio of analyte area and internal standard area with analyte concentration and internal standard concentration. This calibration curve used for quantification of unknown concentration of anlayte of interest. This article provide necessary information about internal standard like its selection procedure, characterization, types and response factor , to all analyst who are connected with drug analysis. This article is more important and I think first article which focuses a clear idea about internal standard use in drug analysis.

Polycyclic Aromatic Hydrocarbons (PAHs) and their Derivatives (O-PAHs, N-PAHs, OH-PAHs): Determination in Suspended Particulate Matter (SPM) – a Review

The aim of this paper is the presentation of the current state-of-the-art about the determination of polycyclic aromatic hydrocarbons (PAHs) and their oxidized forms originating from Suspended Particulate Matter (SPM) samples. The influence of SPM on health is twofold. SPM, as composed of small particles, is dangerous for the respiratory system. Additionally, SPM is a carrier of many hazardous compounds, particularly PAHs. Recently, several researches focus on the derivatives of PAHs, particularly nitro-, oxy- and hydroxy-PAHs, which are more dangerous than the parent PAHs. Both gas and high-performance liquid chromatography with various detection techniques are used to analyze both PAHs and their oxidized forms. Due to the appearance of these compounds in the environment, at a very low level, an analyte concentration step has to be applied prior to analysis. If GC and HPLC techniques are chiefly used as analytical tools for these analyses, the spectrum of analyte concentration procedures is very broad. Many analyte concentration techniques are proposed: from classic liquid-solid extractions, including Soxhlet technique, pressurized liquid extraction (ASE) or microwave oven (MWE) and sonic supported extraction to SPE techniques applications. However, one should remember that PAH determination methods are tools for solving the main problem, i.e., the evaluation the health hazard connected to the presence of SPM in air. Thus, the main drawback of several papers found in this review, i.e., the lack of information concerning limit of detection (LOD) of these methods makes their applicability very limited.

Drift Suppression of Solution-Gated Graphene Field-Effect Transistors by Cation Doping for Sensing Platforms

Solution-gated graphene field-effect transistors (SG-GFETs) provide an ideal platform for sensing biomolecules owing to their high electron/hole mobilities and 2D nature. However, the transfer curve often drifts in an electrolyte solution during measurements, making it difficult to accurately estimate the analyte concentration. One possible reason for this drift is that p-doping of GFETs is gradually countered by cations in the solution, because the cations can permeate into the polymer residue and/or between graphene and SiO2 substrates. Therefore, we propose doping sufficient cations to counter p-doping of GFETs prior to the measurements. For the pre-treatment, GFETs were immersed in a 15 mM sodium chloride aqueous solution for 25 h. The pretreated GFETs showed that the charge neutrality point (CNP) drifted by less than 3 mV during 1 h of measurement in a phosphate buffer, while the non-treated GFETs showed that the CNP was severely drifted by approximately 50 mV, demonstrating a 96% reduction of the drift by the pre-treatment. X-ray photoelectron spectroscopy analysis revealed the accumulation of sodium ions in the GFETs through pre-treatment. Our method is useful for suppressing drift, thus allowing accurate estimation of the target analyte concentration.

Effect of storage duration and analyte concentration on measurement of neutral pH clinical chemistry urine analytes

Background: The aim of the study was focused very keenly in measuring the changes in concentration of sodium, potassium and creatinine in urine, stored for 60 days effect of urinary storage duration of clinical chemistry analytes. This study determined whether patient urine samples can be used for day to day urine quality control.Methods: Spot urine samples were collected from left over samples from the admitted patients in various hospital wards. The samples are kept which its pH was unaltered or unspiked and was aliquoted and deep fridged immediately. These aliquots were melted at an incubator temperature of 86 ºC and was analyzed in the analyzer for 60 days and data were collected for checking variations.Results: With the strenous and continious monitoring from the side of the researchers, the researchers had throughly analysed and found that in both the sets almost all of those analysed urine test of pH 5 and analytes remained very much stable for a period of 60 days which could be used for running daily internal quality controls.Conclusions: Patient urine can be used as internal quality control sample for at least 60 days for sodium, potassium and creatinine. During the 60 days period, there is no appreciable degradation of any of the two sets of samples for sodium, potassium and creatinine measurements.

Numerical Modelling of the Optical Properties of Plasmonic and Latex Nanoparticles to Improve the Detection Limit of Immuno-Turbidimetric Assays

Turbidimetric assays with latex nanoparticles are widely applied for the detection of biological analytes, because of their rapidity, low cost, reproducibility, and automatization. However, the detection limit can be lowered only at the price of a reduced dynamic range, due to the rapid saturation of the light scattering signal at high analyte concentration. Here, we use numerical calculations to investigate the possibility of increasing the performance of immuno-turbidimetric assays without compromising the measurement dynamic range, by combining plasmonic (gold, silver) and latex nanoparticles. Our modelling results show that plasmonic nanoparticles are compatible with a large signal change even when small aggregates are formed, i.e., at low analyte concentration. The working principle relies on the remarkable modification of the surface plasmon band when noble metal nanoparticles form oligomers, and also when latex particles are included in the aggregate. At high analyte concentration, when larger aggregates form, the latex particles can provide the required linear response of standard immuno-turbidimetric assays. Thus, the combination of the two components can be a successful strategy to improve the detection limit and the dynamic range, while maintaining all the advantages of the homogeneous immuno-turbidimetric assays.

Comparison of Dual Beam Dispersive and FTNIR Spectroscopy for Lactate Detection

Near Infrared (800–2500 nm) spectroscopy has been extensively used in biomedical applications, as it offers rapid, in vivo, bed-side monitoring of important haemodynamic parameters, which is especially important in critical care settings. However, the choice of NIR spectrometer needs to be investigated for biomedical applications, as both the dual beam dispersive spectrophotomer and the FTNIR spectrometer have their own advantages and disadvantages. In this study, predictive analysis of lactate concentrations in whole blood were undertaken using multivariate techniques on spectra obtained from the two spectrometer types simultaneously and results were compared. Results showed significant improvement in predicting analyte concentration when analysis was performed on full range spectral data. This is in comparison to analysis of limited spectral regions or lactate signature peaks, which yielded poorer prediction models. Furthermore, for the same region, FTNIR showed 10% better predictive capability than the dual beam dispersive NIR spectrometer.

Ultra-low background signaling cascade amplifier for in vivo fluorescence imaging of hydroxyl radical production induced by testosterone

The designing of cascade assay strategies for sensing ultralow analyte concentration is of crucial importance. However, the conventional strategies are not fit for in vivo detection due to the need...