New Method For Simultaneous Quantification Research Articles

Quantification of trace transformation products of rocket fuel unsymmetrical dimethylhydrazine in sand using vacuum-assisted headspace solid-phase microextraction.

Quantification of unsymmetrical dimethylhydrazine transformation products in solid samples is an important stage in monitoring of environmental pollution caused by heavy rockets launches. The new method for simultaneous quantification of unsymmetrical dimethylhydrazine transformation products in sand samples using vacuum-assisted headspace solid-phase microextraction without addition of water followed by gas chromatography-mass spectrometry is proposed. Decreasing air evacuation time from 120 to 20 s at 23 °C resulted in increased responses of analytes by 25-46% and allowed obtaining similar responses as after evacuation at -30 °C. The best combination of responses of analytes and their relative standard deviations (RSDs) was achieved after air evacuation of a sample (m = 1.00 g) for 20 s at 23 °C, incubation for 30 min at 40 °C, and 30-min extraction at 40 °C by Carboxen/polydimethylsiloxane(Car/PDMS) fiber. The method was validated in terms of linearity (R2=0.9912-0.9938), limits of detection (0.035 to 3.6 ng g-1), limits of quantification (0.12-12 ng g-1), recovery (84-97% with RSDs 1-11%), repeatability (RSDs 3-9%), and reproducibility (RSDs 7-11%). It has a number of major advantages over existing methods based on headspace solid-phase microextraction-lower detection limits, better accuracy and precision at similar or lower cost of sample preparation. The developed method was successfully applied for studying losses of analytes from open vials with model sand spiked with unsymmetrical dimethylhydrazine transformation products. It can be recommended for analysis of trace concentrations of unsymmetrical dimethylhydrazine transformation products when studying their transformation, migration and distribution in contaminated sand.

Simultaneous quantification of eleven short-chain fatty acids by derivatization and solid phase microextraction - Gas chromatography tandem mass spectrometry

As metabolites of the gut microbiome, short-chain fatty acids (SCFAs) played an important role in the diagnosis of the metabolic diseases. Because of the high polarity, high volatility and complex matrix of biological samples, the highly sensitive, selective and accurate method to determine SCFAs remains a major challenge. Herein, a new method for simultaneous quantification of eleven SCFAs by derivatization combined with solid phase microextraction (SPME) and gas chromatography tandem mass spectrometry (GC–MS/MS) was developed. Isobutyl chloroformate coupled with isobutanol was used as the reaction reagent to derivatize SCFAs. The method validation data showed a satisfactory linearity with the linear regression coefficients (R) ranging from 0.9964 to 0.9996. The limit of detection (LOD) of all SCFAs ranges from 0.01 ng·mL−1 to 0.72 ng·mL−1 and the limit of quantification (LOQ) ranges from 0.04 ng·mL−1 to 2.41 ng·mL−1. The intra-day and inter-day precision (RSDs) ranged from 0.65% to 8.92% and 1.62% to 15.61%, respectively. The recovery ranged from 88.10% to 108.71%. Finally, the developed method was successfully used to determine SCFAs in mice fecal sample, and ten of the SCFAs were found in feces of mice, including formic acid.

Validation of an innovative analytical method for simultaneous quantification of alpha-cyano-4-hydroxycinnamic acid and the monoclonal antibody cetuximab using HPLC from PLGA-based nanoparticles

Accumulating evidence has been suggesting that combining two or more anticancer drugs can provide additive or synergistic effects, improving therapeutic efficacy and delaying resistance. Nowadays, advances in nanotechnology-based delivery systems have enabled the association of different drugs into a single carrier and provided therapeutic gains to the proposed regimen. However, a new strategy also requires innovative analytical approaches that assess loading capacity, biological performance, and also comprehend the mechanisms of action. Alpha-cyano-4-hydroxycinnamic acid (CHC) and the monoclonal antibody (mAb) cetuximab (CTX) are explored worldwide for their therapeutic benefits against multiple cancer cells. The present work aims to develop and validate a new method for simultaneous quantification of CHC and CTX in nanoparticulate systems by using reverse phase high-performance liquid chromatography (RP-HPLC) with ultraviolet (UV) detection for CHC, and fluorescence detection for CTX. This method was designed following the guidelines of the International Conference on Harmonization ICH Q2 (R1) and the Food and Drug Administration (FDA) - Guidance for Bioanalytical Method Validation. Chromatographic separation was performed on a C18 column with the mobile phase composed by water, 0.1 % (v/v) trifluoroacetic acid (TFA) and acetonitrile (ACN)-0.1 % TFA on gradient mode at a flow rate of 0.6 mL/min. The performance of the present method was evaluated by system suitability; therefore, linearity, accuracy, precision, detection, limit of detection / limit of quantification, and robustness were also highlighted. Specificity was demonstrated by the chromatographic analyses of CHC and CTX, subjected to several informative stress conditions. The developed method was also successfully used for the first time to quantify the CHC and CTX content in poly(lactic-co-glycolic acid)-based nanoparticles. In conclusion, this new and rapid method presented acceptable analytical performance and can be helpful to simultaneously quantify CHC and CTX in future studies applied to anticancer therapy.

A new method for simultaneous quantification of fosphenytoin, phenytoin and its primary metabolite 5-(4-hydroxyphenyl)-5-phenylhydantoin in whole blood by ultra-performance liquid chromatography-tandem mass spectrometry.

A method for simultaneous quantification of fosphenytoin (F-PHT), phenytoin (PHT) and its main metabolite 5-(4-hydroxyphenyl)-5-phenylhydantoin (HPPH) in whole blood was developed and validated using ultra-performance liquid chromatography-tandem mass spectrometry. Whole blood samples were pretreated by liquid-liquid extraction with acetonitrile and methanol. Chromatographic separation was performed using a CORTECS™ UPLC® C18 (2.1 × 50 mm i.d., particle size 1.6 μm) analytical column, and water containing 10 mM ammonium formate and acetonitrile as the mobile phase. Quantification of the analytes was carried out using mass chromatography with each product ion referenced against phenytoin-d10 as an internal standard. Calibration curves exhibited good linear relationships in a range from 0.005 to 50 μg/ml with correlation coefficients exceeding 0.995. The limits of detection were estimated to be 0.002-0.01 μg/ml. The accuracies and precisions were 96.2-104.3% and 0.7-10.7%, respectively. The recovery efficiencies were in the range of 42.4-59.2%. Matrix effects were observed for PHT and HPPH, with signal suppression ranging from -6.6 to -32.2%. Matrix effect for F-PHT (-5.0 to 8.9%) was less than those for PHT and HPPH. All analytes were stable under different storage conditions. This method was successfully applied for the quantification of F-PHT, PHT and HPPH in rat whole blood samples taken after bolus intravenous administration of F-PHT.

Simultaneous determination of binary solution of triphenylmethane dyes in complex matrices onto magnetic amino-rich SWCNT using second-order calibration method.

This study suggested a new method for simultaneous quantification of two dyes in complex matrices using second-order data by spectrophotometry. Second-order data was generated simply without any expensive instrument using two independent variables including wavelength and the monotonic addition of sodium dodecyl sulfate. Solid-phase extraction (SPE) based on amino-rich magnetic single-walled carbon nanotube as an adsorbent was employed prior to second-order data generation. SPE optimization was performed by Box-Behnken design, and parameters and their interaction which were dependent on the simultaneous extraction of dyes were examined. Competitive Langmuir and Freundlich isotherms for a binary system and individual dyes could all represent the equilibrium data well. The second-order data was processed by parallel factor analysis (PARAFAC and PARAFAC2) and multivariate curve resolution-alternating least squares (MCR-ALS). Figures of merit of the model including a limit of detection of 3.0 and 2.5ngmL-1 for crystal violet and malachite green, respectively, were estimated using the MCR-ALS method. The combination of the second-order calibration and SPE presents an easy and versatile method for determination of the mixture of two dyes in the presence of uncalibrated interferences in environmental water, synthetic, and fish samples with the recoveries of 94-104.

Simultaneous quantification of curcuminoids and xanthorrhizol in Curcuma xanthorrhiza by high-performance liquid chromatography

ABSTRACTA new method for simultaneous quantification of curcuminoids and xanthorrhizol (XNT) in Curcuma xanthorrhiza was developed and validated using high-performance liquid chromatography with diode-array UV–Vis detector. The chromatographic separation was achieved on a Phenomenex C18 at room temperature with the mobile-phase acetonitrile −0.001% formic acid in gradient elution system and delivered at a flow rate of 1 mL/min. Detection wavelength 425 nm was used for curcuminoids and 224 nm for XNT. System suitability, linearity, precision, accuracy, limit of detection, limit of quantitation, and stability were evaluated and were found in good agreement with Association of Official Analytical Chemists guidelines for single-laboratory validation. The proposed method was found to be precise, accurate, and reliable and also could be applied for the simultaneous quantitative analysis of curcuminoids and XNT in C. xanthorriza raw material and its herbal medicinal product.

Simultaneous Quantification of Amino Metabolites in Multiple Metabolic Pathways Using Ultra-High Performance Liquid Chromatography with Tandem-mass Spectrometry

Metabolites containing amino groups cover multiple pathways and play important roles in redox homeostasis and biosyntheses of proteins, nucleotides and neurotransmitters. Here, we report a new method for simultaneous quantification of 124 such metabolites. This is achieved by derivatization-assisted sensitivity enhancement with 5-aminoisoquinolyl-N-hydroxysuccinimidyl carbamate (5-AIQC) followed with comprehensive analysis using ultra-high performance liquid chromatography and electrospray ionization tandem mass spectrometry (UHPLC-MS/MS). In an one-pot manner, this quantification method enables simultaneous coverage of 20 important metabolic pathways including protein biosynthesis/degradation, biosyntheses of catecholamines, arginine and glutathione, metabolisms of homocysteine, taurine-hypotaurine etc. Compared with the reported ones, this method is capable of simultaneously quantifying thiols, disulfides and other oxidation-prone analytes in a single run and suitable for quantifying aromatic amino metabolites. This method is also much more sensitive for all tested metabolites with LODs well below 50 fmol (at sub-fmol for most tested analytes) and shows good precision for retention time and quantitation with inter-day and intra-day relative standard deviations (RSDs) below 15% and good recovery from renal cancer tissue, rat urine and plasma. The method was further applied to quantify the amino metabolites in silkworm hemolymph from multiple developmental stages showing its applicability in metabolomics and perhaps some clinical chemistry studies.

New Method for Simultaneous Quantification of 12 Ginsenosides in Red Ginseng Powder and Extract: In-house Method Validation

For quality control of components in Korean red ginseng powder and extract, a new method for simultaneous quantification of 12 ginsenosides (Rg1, Re, Rf, Rh1, Rg2[S], Rg2[R], Rb1, Rc, Rb2, Rd, Rg3[S], and Rg3[R]) was studied. Compared to the official method for quantification of marker substances (ginsenosides Rg1 and Rb1), the proposed methods were guaranteed by in-house method validation. Several criteria such as linearity, specificity, precision and accuracy were evaluated. For red ginseng powder, recovery (averaging 95% to 105%) was calculated, and analysis of variance was carried out to estimate the relative standard deviation (0.20% to 2.12%). For red ginseng extract, the average recovery rate was 90% to 99% and the relative standard deviation was 0.39% to 2.40%. These results indicate that the proposed method could be used in the laboratory for determination of 12 ginsenosides in red ginseng powder and extract. In addition, this method was found to be suitable for quality control of ginseng products and potentially offer time and cost benefits.

Quantification of 15N-Nitrate in Urine with Gas Chromatography Combustion Isotope Ratio Mass Spectrometry to Estimate Endogenous NO Production

The use of stable isotope labeled substrates and subsequent analysis of urinary nitrate, forms a noninvasive test for evaluation of the in vivo NO metabolism. The present paper describes a new method for simultaneous quantification of (15)N-nitrate and total nitrate with gas chromatography combustion isotope ratio mass spectrometry (GC-C-IRMS). Nitrate, isolated from urine with a nitrate selective resin, was reduced to nitrite using copperized cadmium. Subsequently, Sudan I was formed by diazotation. Sudan II was added as internal standard, and both molecules were analyzed with GC-C-IRMS as tert-butyldimethylsilyl derivatives. The accuracy was determined during a recovery study of two different known nitrate concentrations and two (15)N-enrichments. A recovery of 101.6% and 103.9% for total nitrate and 107.6% and 91.2% for (15)N-nitrate was obtained, respectively. The validated method was applied on complete 72 h urine collections after intravenous administration of (15)N-nitrate and (15)N-arginine in humans. On average, 51.8% (47.0-71.0%) of administered (15)N-nitrate was excreted, while 0.68% (0.44-1.17%) of (15)N-arginine was metabolized to nitrate. In conclusion, this method can be used for accurate simultaneous determination of (15)N-nitrate and total nitrate concentrations in urine and can be applied in clinical studies for noninvasive evaluation of NO metabolism in vivo.

New simple liquid chromatographic method for the determination of trimethoprim, sulfadiazine and N4-acetylsulfadiazine in plasma of broilers

A new method for simultaneous quantification of trimethoprim, sulfadiazine and N 4-acetylsulfadiazine in plasma of broilers at levels down to 13–16 ng/ml has been developed. Samples were deproteinized with acetonitrile, defatted with hexane, and extracted with dichloromethane. Chromatographic analysis was carried out on a C 18 column in the presence of tetrabutylammonium hydrogen sulfate, a competing base, while detection was performed at 240 nm for trimethoprim, and 270 nm for both sulfadiazine and N 4-acetylsulfadiazine. Accuracy and precision data showed recoveries and relative standard deviation values better than 87.3% and 3.1%, respectively, for all three analytes. The good analytical characteristics of the method could allow limits of detection in the low ng/ml range to be realised. The method was successfully applied to determine drug concentrations in plasma samples from broilers administered a combination of sulfadiazine and trimethoprim.

A new method for simultaneous quantification of uncoupling and inhibitory activity of organic pollutants in energy‐transducing membranes

AbstractA new, mechanistically based approach is presented for the quantitative determination of the uncoupling and inhibitory activity of compounds interfering with energy transduction. Time‐resolved spectroscopy of single‐turnover events in the photosystem of the photosynthetic bacterium Rhodobacter sphaeroides can quantitatively distinguish uncoupling from inhibition. The decay kinetics of the membrane potential after a single turnover flash are used as a measure of uncoupling activity, and the redox kinetics of several components of the electron transfer chain are used as indicators of specific inhibition at various potential inhibitory sites. Results are presented for 21 nitrated and chlorinated phenols, some reference uncouplers, and some anisoles. Inhibition was exclusively detected at one specific quinone binding site, the quinone reductase site Qi. For most phenols, uncoupling was observed at lower concentrations than inhibition with the exception of alkylated 2,6‐dinitrophenols and 2,4,6‐trichlorophenol, where both effects occurred in the same concentration range. No direct correlation was observed between the uncoupling and inhibitory activity of a given compound. The data obtained with this new method correlate well with data from various bioassays on energy‐transducing systems, indicating that this method may also be well suited as a screening tool for compounds suspected to interfere with energy transduction.

Purine metabolites in serum of higher primates, including man

Using a new method for simultaneous quantification of hypoxanthine, xanthine, uric acid, and allantoin by means of high-pressure liquid chromatography, purine metabolites of 18 species of higher primates, including man, have been determined. The data thus produced indicate that the serum concentrations of purine metabolites in primates are influenced by nutrition, sexual hormones, and the procedures used in catching the animals for venipuncture. In the Callitrichidae examined, serum concentrations of purines differ significantly from species to species. The results of a nutritional test show that Callithrix jacchus possesses an efficient system for degradation of dietary purines.