Method For Determination Of Concentration Research Articles

X-ray fluorescence-based method for the quantitative determination of uranium in the aqueous solutions

Currently, one of the important issues in the field of nuclear technology is providing special handling with respect to nuclear materials, due to their energy and commercial significancy, as well as their potential radiation contamination threat. There is a necessity to have information about the full qualitative and quantitative composition of the sample as a part of special handling with nuclear materials. Spectrometric methods solve this problem effectively. One of these methods is the X-ray fluorescence analysis, which is fast, nondestructive and environmentally friendly with a high accuracy and reproducibility of the results. Development of uranium quantitative determination method in aqueous solutions to solve the problems of accounting and control of nuclear materials is the subject of research in this article. The development of the uranium concentration determination method in the aqueous solutions of uranyl nitrate UO2(NO3)2 was carried out using Spectroscan MAKC-G – wavelength dispersive crystal diffraction XRF spectrometer.

A supported liquid extraction LC-MS/MS method for determination of concentrations of GDC-0425, a small molecule Checkpoint kinase 1 inhibitor, in human plasma.

A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the determination of GDC-0425 concentrations in human plasma has been developed and validated. Supported liquid extraction was used to extract plasma samples (50 μL) and the resulting samples were analyzed using reverse-phase chromatography and mass spectrometry coupled with a turbo-ionspray interface. The mass analysis of GDC-0425 was performed using multiple reaction monitoring transitions in positive ionization mode. The method was validated over the calibration curve range of 1.00-1000 ng/mL using linear regression and 1/x2 weighting. Within-run relative standard deviation ranged from 0.8 to 5.1%, while between-run RSD varied from 1.9 to 4.7% for QCs. The accuracy ranged from 90.0 to 101.0% of nominal for within-run and from 94.0 to 100.0% of nominal for between-run. Overall extraction recovery was 87.4% for GDC-0425 and 87.9% for GDC-0425-d9 . Stability of GDC-0425 was established in human plasma for 374 days at -20 and -70 °C and established in reconstituted sample extracts for 88 h when stored at 2-8 °C. Stable-labeled internal standard was used to minimize matrix effects. This assay was used to characterize the pharmacokinetics of GDC-0425 in cancer patients.

Choline-induced selective fluorescence quenching of acetylcholinesterase conjugated Au@BSA clusters

We have developed a highly selective sensitive fluorescent detection of acetylcholine (ACh) using bovine serum albumin (BSA) protected atomically precise clusters of gold. The gold quantum clusters (AuQC@BSA) synthesized using bovine serum albumin and conjugated with acetylcholinesterase (AChE), an enzyme specific for acetylcholine, resulting in AuQC@BSA-AChE. The enzyme, AChE hydrolyzes acetylcholine (ACh) to choline (Ch) which in turn interacts with AuQC@BSA-AChE and quenches its fluorescence, enabling sensing. We have carried out the real time monitoring of the hydrolysis of ACh using electrospray ionization mass spectrometry (ESI MS) to find out the mechanism of fluorescent quenching. The validity of present method for determination of concentration of acetylcholine in real system such as blood was demonstrated. Further, the sensor, AuQC@BSA-AChE can be easily coated on paper and an efficient and cheap sensor can be developed and detection limit for ACh is found to be 10nM. The fluorescent intensity of AuQC@BSA-AChE is sensitive towards acetylcholine in range of 10nM to 6.4µM. This suggests that AuQC@BSA-AChE has an excellent potential to be used for diagnosis of various neuropsychological and neuropsychiatric disorders.

Pharmacokinetics study on costunolide and dehydrocostuslactone after administration of traditional Chinese medicine Weichang'an pills

A HPLC-MS/MS multiple-reaction monitoring (MRM) quantitative analysis was made to establish a determination method for drug concentrations of costunolide (Co) and dehydrocostuslactone (De) in blood samples in the positive ion mode, with diazepam as the internal standard substance, in order to study the pharmacokinetic process of sesquiterpene lactones costunolide and dehydrocostuslactone after the oral administration of Weichang'an pills, and provide an theoretical basis for further studies on the substance basis for the anti-diarrhea effect of Weichang'an pills. In the blood samples, Co and De showed a good linearity within concentration ranges 0.700 0-769.7, 2.510-956.0 μg x L(-1), respectively. The results of precision, stability and recovery experiences proved the stability and reliability of the plasma concentration determination method. After the oral administration, the concentrations of Co and De in plasma increased with the increase in dose, with T(max) between 10.65-12.98 h, indicating a long time to reach peak plasma concentrations; C(max) of costunolide and dehydrocostuslactone ranged between 3.750-5.450,15.34-44.52 μg x L(-1), respectively. The in vivo adsorption of Co and De conformed to the one-compartment model, with a longer time to attain the peak plasma concentrations. These results provided an experimental basis for revealing the active substance basis and clinical medication of Weichang'an pills.

Effect of Jinlida on changes in expression of skeletal muscle lipid transport enzymes in fat-induced insulin resistance ApoE-/- mice

To study the effect of Jinlida on changes in expression of skeletal muscle lipid transport enzymes in fat-induced insulin resistance ApoE -/- mice. Eight male C57BL/6J mice were selected in the normal group (NF), 40 male ApoE -/- mice were fed for 16 weeks, divided into the model group (HF), the rosiglitazone group ( LGLT), the Jinlida low-dose group (JLDL), the Jinlida medium-dose group (JLDM), the Jinlida high-dose group (JLDH) and then orally given drugs for 8 weeks. The organization free fatty acids, BCA protein concentration determination methods were used to determine the skeletal muscle FFA content. The Real-time fluorescent quantitative reverse transcription PCR ( RT-PCR) and Western blot method were adopted to determine mRNA and protein expressions of mice fatty acids transposition enzyme (FAT/CD36), carnitine palm acyltransferase 1 (CPT1), peroxide proliferators-activated receptor α( PPAR α). Jinlida could decrease fasting blood glucose (FBG), cholesterol (TC), triglyceride (TG), free fatty acid (FFA) and fasting insulin (FIns) and raise insulin sensitive index (ISI) in mice to varying degrees. It could also up-regulate mRNA and protein expressions of CPT1 and PPARα, and down-regulate mRNA and protein levels of FAT/CD36. Jinlida can improve fat-induced insulin resistance ApoE -/- in mice by adjusting the changes in expression of skeletal muscle lipid transport enzymes.

Determination of Optical Characteristics of Scattering Biological Media Based on Bimodality Effect of Temporal Distribution of Laser Pulses

A method for simultaneous determination of absorption and scattering coefficients and the anisotropy factor of scattering media is described. This method is based on the bimodal effect of the temporal distribution of short laser pulses after their propagation through a homogeneous scattering layer. Spectral dependences of these physical characteristics were obtained for model biological scattering samples.

The Improvement of Pretreatment on the Determination of Mercuryin Industrial Wastewater

Discussed with the (MWD) for Nitrogen Oxide interference of the mercury determination in wastewater, studied the method of elimination volatile nitrogen oxides rapidly. Optimized the conditions by microwave-digestion hydride generation atomic absorption method for determination of mercury in daily chemical .The detection limit of the method was 0.4μg/L, the lower limit of quantification was 1.2μg/L, the relative standard deviation determined by spiked samples is 1.5% and recovery from 94% to 103%.

Determination of As and Se in coal and coal combustion products using closed vessel microwave digestion and collision/reaction cell technology (CCT) of inductively coupled plasma mass spectrometry (ICP-MS)

Toxic elements arsenic and selenium in coal are of great concern mainly because of their adverse effects on human health during coal combustion. This paper describes the concentration determination of As and Se in coal and coal combustion products (CCPs), performed by collision/reaction cell technology (CCT) of inductively coupled plasma mass spectrometry (ICP-MS; collectively ICP-CCT-MS) after closed vessel microwave digestion. The reagents for 50-mg coal sample digestion are 2-ml 40% (v/v) HF and 5-ml 65% (v/v) HNO3 but for the CCP samples, the reagents include 5-ml 40% HF and 2-ml 65% HNO3. To significantly diminish the argon-based interferences at mass to charge ratios (m/z) 75 (40Ar35Cl) and 78 (40Ar38Ar), a helium and hydrogen mixture was used in the optimized hexapole collision cell. The results showed that CCT technology can effectively diminish the spectral interferences of the Ar-based polyatomic ions 40Ar35Cl and 40Ar38Ar to 75As and 78Se, respectively. The method detection limit of As and Se is 0.024 and 0.095μg/l, respectively, and their linearity of the calibration curves in the range 0–100μg/l has a determination coefficient r2>0.9999. The determination of As and Se in NIST standard reference materials of coal and fly ash samples showed that ICP-CCT-MS plus closed vessel microwave digestion is a reliable method for concentration determination of the two elements in coal and CCPs.

Quantitative Response of IMS Detector for Mixtures Containing Two Active Components

This study describes the relationship between the output signal of the ion mobility spectrometry (IMS) detector and the concentrations of two compounds being simultaneously introduced into the reaction section. Investigations were performed for three pairs of compounds, that is, dimethyl methylphosphonate (DMMP) and acetone, methyl tert-butyl ether (MTBE), and acetone, as well as trimethylamine (TMA) and n-nonylamine (NA). Vapors of the investigated compounds were produced in a two-channel generator with permeation sources and a dilution system based on mass-flow controllers. The generator design and the method of concentration determination are discussed in this paper. It was found that admixture can differently influence detection of an analyte. The presence of acetone does not effect the signal corresponding to dimer ions of DMMP. For pairs MTBE + acetone and TMA + NA characteristic peaks of analyte ions diminish with growing concentration of admixture, however, the detection based on the peak of the asymmetric dimer containing proton-bound molecules of both compounds is effective. For the detection of TMA in the presence of NA, the signal generated by the asymmetric dimer ions is meaningfully higher than the signals of monomer or dimer TMA ions measured without the NA admixture. The course of calibration dependencies was analyzed on the basis of a simple mathematical model of the reaction region. This model provided an estimation of the intensity of the signal for a given ionic species for definite concentration of analyte.

An improved Compton scattering method for determination of concentration of solutions

An improved Compton scattering method for determination of concentration of low-Z solutions is presented. The Monte Carlo (MC) numerical simulation of the scattering phenomena is done using the MCNP code. A unique non-linear extrapolation method is followed in correcting the scattered intensity for self-absorption and multiple scattering. The density ratios obtained using non linear extrapolated scattered intensity values are free from self-absorption and multiple scattering and agree well with the standard ones within experimental errors. The sensitivity study of transmission and scattering methods for determination of concentration of solutions having closer attenuation parameters at 661.6keV is carried out to predict the range of effectiveness and suitability of these methods. The slopes (sensitivity/unit concentration) of the curves obtained from scattering method are higher by a factor of 1.26 compared to those of the transmission method in the measured range of concentrations.

Chemical Composition and Antimicrobial Activity of the Essential Oil from the Peel of Shatian Pummelo (Citrus Grandis Osbeck)

The chemical composition of the essential oil obtained from the peel of Shatian pummelo was analyzed by gas chromatography/mass spectrometry. Twenty-one components were identified. The monoterpenes and sesquiterpene hydrocarbons were the principal compound groups with 96.64% (w/w) of the total oil, among which, limonene was observed dominant (89.96 ± 1.64%), followed by β-myrcene (4.49 ± 0.38%), α-pinene (0.63 ± 0.05%), 3-carene (0.48 ± 0.04%), caryophyllene (0.47 ± 0.04%), and other minor constitutes. Esters, alcohols, ketones, aldehydes, and ether represented 3.15% of the total oil. Results by the disc diffusion method and minimum inhibitory concentration determination method showed that the essential oil contained a wide-spectrum antimicrobial activity against Penicillium chrysogenum ATCC 10106, Bacillus subtilis ATCC 21616, Staphylococcus aureus ATCC 25923, and Escherichia coli ATCC 25922, with their inhibition zones ranging from 8.27 ± 1.07 mm to 20.71 ± 1.50 mm. The MIC values were ranging from 4.69 to 37.50 μL/mL. However, no inhibition effect was observed on the Aspergillus niger ATCC 16888.

Simultaneous determination of isoorientin, scutellarin and cynaroside in rat plasma and pharmacokinetics by UPLC-MS/MS

To establish a UPLC-MS/MS analysical method for simultaneous determination of concentrations of isoorientin, scutellarin and cynaroside in rat plasma and to study their pharmacokinetic characteristics after intravenous injection of 3 doses of Fufang Hongcao in rats. Acidified plasma samples were precipitated for protein with methanol. Waters Acquity BEH C18 column was adopted for spectrum, with mobile phase as 0. 1% formic acid acetonitrile-0. 1% formic acid-water gradient elution. Detection was carried out by the multiple reaction monitoring (MRM) positive ion mode with ESI ionization source. Three flavonoids show a good linear relationship, with the extraction recovery ranging between 78.56% and 101.91% and a high intra-and inter-day precisions and accuracy. The MRT of the three flavonoids were all lower than 22 min in rats. The above men tioned method is so specific, rapid, sensitive that it is suitable for pharmacokinetic studies of Fufang Hongcao injection in rats.

Determination of Polychlorinated Biphenyls and Organochlorine Pesticides in Human Serum by Gas Chromatography with Micro-Electron Capture Detector

A method for determination of concentrations of polychlorinated biphenyl congeners (PCB-28, 52, 101, 118, 138, 153, 156, and 187) and organochlorine pesticides (hexachlorobenzene, alpha-hexachlorocyclohexane, beta-hexachlorocyclohexane, gamma-hexachlorocyclohexane, delta-hexachlorocyclohexane, p,p'-dichlorodiphenyl dichloroethylene, o,p'-dichlorodiphenyl trichloroethane, p,p'-dichlorodiphenyl dichloroethane, p,p'-dichlorodiphenyl trichloroethane, alpha-chlordane, gamma-chlordane, heptachlor, heptachlor epoxide, and aldrin) in human serum is developed. Recovery is assessed with artificial serum, in which PCBs and OCPs could not be detected. The method is then confirmed with pooled human serum. Experiments are performed by adding two concentrations of analytes (0.5 µg/L and 1.0 µg/L) to both matrices. The sample pretreatment process involves denaturing with a mixture of water-1-propanol (v:v, 85:15), extraction with a C-18 cartridge, and cleanup with an Alumina B cartridge. This process required about 2 mL of serum. The limit of detection ranged from 0.05-0.35 µg/L for all the analytes. Recovery of analytes at low and high spiking concentrations varied from 63-122% and 61-124% for artificial serum and pooled human serum, respectively. Relative standard deviation was lower than 16% and 18% for artificial serum and pooled human serum, respectively. Stability of the method, expressed as relative standard deviation, was lower than 14%. The method has been applied in epidemiological research.

Determination of two reactive dyes concentration in dyed cotton fabric

The purpose of this paper was to determine the unknown concentration of dichlortriazinyl reactive dyes, namely Reactive Yellow 22 and Reactive Blue 163, in dyed cotton fabric. The samples of cotton fabric were dyed individually with each dye as well as with a mixture of two dyes. The unknown concentrations of dyes were determined by measuring the corresponding reflectance values of dyed fabric samples and then using the relation between the concentration and reflectance values of the samples. The method set by Kubelka and Munk was used. The accuracy and repeatability of the concentrations determination were calculated by the statistical processing of the data obtained by measurements. Relative errors of individual determination of Reactive Yellow 22 and Reactive Blue 163 were 3.66% and 5.94% respectively. Relative errors in determination of Reactive Yellow 22 and Reactive Blue 163 in a mixture were 3.47% and 3.19% respectively. The results showed that reflectance spectrophotometry can be successfully used as the method for concentration determination of Reactive Yellow 22 and Reactive Blue 163 in dyed cotton fabric and can therefore be applied as the shade control method in dyeing.

A solid phase extraction-liquid chromatographic–tandem mass spectrometry method for determination of concentrations of GDC-0941, a small molecule class I phosphatidylinositide 3-kinase inhibitor, to support clinical development

A solid phase extraction (SPE) liquid chromatographic–tandem mass spectrometry (LC–MS/MS) method for the determination of GDC-0941 concentrations in human plasma has been developed and validated to support clinical development. An Oasis MCX 10 mg 96-well SPE plate was used to extract plasma samples (50 μL) and the resulting extracts were analyzed using reverse-phase chromatography and mass spectrometer coupled with a turbo-ionspray interface. The method was validated over the calibration curve range 0.500–500 ng/mL with linear regression and 1/ x 2 weighting. Within-run relative standard deviation (%RSD) ranged from 1.5 to 11.5%, while the between-run %RSD varied from 0.0 to 4.4%. The accuracy ranged from 96.0% to 110.0% of nominal for within-run and 98.0% to 108.0% of nominal for between-run at all concentrations including the LLOQ quality control at 0.500 ng/mL. Extraction recovery of GDC-0941 was between 79.0% and 86.2%. Stability of GDC-0941 was established in human plasma for 602 days at −70 °C and 598 days at −20 °C, respectively, and established in reconstituted sample extracts for 167 h when stored at room temperature. Internal standard normalized matrix factor was 1.1, demonstrating that the use of the stable-labeled internal standard GDC-0941-d 8 effectively compensated observed matrix effect and resulting in no adverse impact on the quality of the data produced. This assay was used for the determination of GDC-0941 human plasma concentrations over a sufficient time period to determine pharmacokinetic parameters at relevant clinical doses.

Determination of IMC-80BH Corrosion Inhibitor Concentration and Practical Application in Gas Field

The ability of IMC-80BH corrosion inhibitor is proven to be excellent in earlier indoor static and flowing evaluation and it is worthwhile to determine the inhibitor concentration to maintain the optimum concentration for the sake of effective gas well protection. A improved concentration determination method is aboratively investigated. The maximum absorption wavelengths, buffer solution, reaction time and additive dosage of chromogenic reagent XD are detected successively and the standard curve of liquid phase behaves better than oil gas. The sample verification demonstrates that such determination measurement is reliable and precise. The four representative gas wells including G8-7, S59, W26-5 and G49-6 in service are also determined. The determination result offered substantial basis to analyze and select appropriate inhibitor injection program and dosage.

Simultaneous measurement of endogenous cortisol, cortisone, dehydroepiandrosterone, and dehydroepiandrosterone sulfate in nails by use of UPLC–MS–MS

Steroid hormone concentrations are mostly determined by using different body fluids as matrices and applying immunoassay techniques. However, usability of these approaches may be restricted for several reasons, including ethical barriers to invasive sampling. Therefore, we developed an ultra-performance LC-MS-MS method for high-throughput determination of concentrations of cortisol, cortisone, dehydroepiandrosterone (DHEA), and DHEA sulfate (DHEAS) in small quantities of human nails. The method was validated for linearity, limits of detection and quantification, recovery, intra and interassay precision, accuracy, and matrix effect. Samples from 10 adult women were analyzed to provide proof-of-principle for the method's applicability. Calibration curves were linear (r(2) > 0.999) in the ranges 10-5000 pg mg(-1) for cortisol, cortisone, and DHEAS, and 50-5000 pg mg(-1) for DHEA. Limits of quantification were 10 pg mg(-1) for cortisol, cortisone, and DHEAS, and 50 pg mg(-1) for DHEA. The sensitivity and specificity of the method were good, and there was no interference with the analytes. Mean recovery of cortisol, cortisone, DHEA, and DHEAS was 90.5%, 94.1%, 84.9%, and 95.9%, respectively, with good precision (coefficient of variation <14% for all analytes) and accuracy (relative error (%) -8.3% to 12.2% for all analytes). The median (pg mg(-1), range) hormone concentrations were 69.5 (36-158), 65 (32-133), 212 (50-1077), and 246 (115-547) for cortisol, cortisone, DHEA, and DHEAS, respectively. This method enables measurement of cortisol, cortisone, DHEA, and DHEAS in small quantities of human nails, leading to the development of applications in endocrinology and beyond.

Microdialysis and HPLC method for determination of concentration of pantoprazole in rat striatum after combined administration with borneol

To observe the influence of borneol, a traditional Chinese medicine, on the concentration of ceftriaxone in the rat brain striatum and evaluate the relativity. The sample of cerebrospinal fluid in the rat brain striatum was collected via brain microdialysis technology, and then the contents of ceftriaxone in standard preparation and sample were detected by high efficiency liquid chromatography combined with diode array detector respectively and analyzed statistically. The concentration of ceftriaxone in rat brain striatum in the ceftriaxone + Borneol group was compared with that in the ceftriaxone-only group. The concentration of ceftriaxone in the rat brain in the ceftriaxone + Borneol group (13.01-4.43 mg x L(-1)) is significantly higher than that in the ceftriaxone-only group (2.41-0.94 mg x L(-1)). Borneol can promote ceftriaxone through blood-brain barrier, and increase the concentration thereof in striatum.

Optical Study of the Reduction of Hexavalent Chromium by Iron-Based Nanoparticles

In this paper, a simple method was presented to measure the concentration change in the Cr(VI)-contained waste water during treatment by nanoparticles, based on its optical absorption spectral evolution which exhibits a good linear relationship between the absorbance of the peak at 348 nm and Cr6+ ion concentration. The iron and Fe/Pd bimetal nanoparticles were prepared and used for removal of Cr6+ in waste water. It has been found that presented method for concentration determination based on optical spectral evolution is effective and flexible. The nanoparticles have higher efficiency than normal iron powders and Fe/Pd bimetallic nanoparticles show faster removal of the Cr6+ than iron nanoparticles. The study is of importance in environmental remediation or pollution treatment of heavy metal ions in water and even soil.

Microvolume Protein Concentration Determination Using the NanoDrop 2000c Spectrophotometer

Traditional spectrophotometry requires placing samples into cuvettes or capillaries. This is often impractical due to the limited sample volumes often used for protein analysis. The Thermo Scientific NanoDrop 2000c Spectrophotometer solves this issue with an innovative sample retention system that holds microvolume samples between two measurement surfaces using the surface tension properties of liquids, enabling the quantification of samples in volumes as low as 0.5-2 μL. The elimination of cuvettes or capillaries allows real time changes in path length, which reduces the measurement time while greatly increasing the dynamic range of protein concentrations that can be measured. The need for dilutions is also eliminated, and preparations for sample quantification are relatively easy as the measurement surfaces can be simply wiped with laboratory wipe. This video article presents modifications to traditional protein concentration determination methods for quantification of microvolume amounts of protein using A280 absorbance readings or the BCA colorimetric assay.