Calibration Curve For Quantitative Analysis Research Articles

Enhancing Oral Absorption of Orlistat through Gastroretentive Mucoadhesive Pellets: Formulation and Evaluation

Aim: The aim of this study was to develop gastroretentive mucoadhesive pellets of Orlistat to improve its oral bioavailability and enhance its absorption.
 Methods: Orlistat pellets were prepared using Hydroxy Propyl Methyl Cellulose (HPMC) K100M, Sodium Carboxy Methyl Cellulose (NaCMC), Carbopol 934P, and Polyvinyl Pyrrollidone (PVP) K30 in varying ratios. Physical characteristics of the tablets were evaluated, and compatibility studies were performed between Orlistat and the excipients. Swelling index, mucoadhesion strength and drug release were measured for each formulation. Drug release kinetics and stability studies were carried out.
 Results: The combination of HPMC K100M, NaCMC, Carbopol 934P and PVP K30 provided balanced release and mucoadhesion with F13 showing sustained release up to 16 hours. The calibration curve demonstrated a good linear relationship between Orlistat concentration and absorbance over the range of 10 to 50 ?g/ml. Swelling index increased with time and polymer concentration and mucoadhesion strength increased with polymer viscosity and concentration. Drug release from formulations containing HPMC K100M, NaCMC and Carbopol 934P were 12-14 hours, 10-12 hours and 8-11 hours, respectively. Combination polymers in F10-F13 provided balanced release and mucoadhesion, with F13 showing sustained release up to 16 hours. The drug release followed zero order kinetics with non-Fickian diffusion. Stability studies on the optimized F13 formulation showed no significant changes in appearance, hardness, mucoadhesion or drug release over 3 months.
 Conclusion: The combination of HPMC K100M, NaCMC, Carbopol 934P and PVP K30 improved the oral bioavailability and absorption of Orlistat. The study demonstrated the importance of compatibility studies and the use of calibration curves for quantitative analysis. The findings provide valuable insights into the development of drug delivery systems for poorly bioavailable drugs.

Gold-based strip sensor for the rapid and sensitive detection of butralin in tomatoes and peppers

Butralin is a widely used dinitroaniline herbicide. Butralin residues in vegetables or fruits represent a threat to human health. In this study, we developed a rapid and sensitive gold-based lateral flow immunoassay (LFIA) for butralin detection in tomato and green pepper samples based on a screened monoclonal antibody (mAb) against butralin. The mAb possessed a half-maximal inhibitory concentration (IC50) of 12.7 ng/mL, with no cross-reactivity toward other dinitroaniline herbicides. The established LFIA strip had a visible limit of detection (LOD) of 50 ng/g and a cut-off value of 2000 ng/g in tomato and green pepper samples. According to the calibration curves for quantitative analysis, the calculated LODs of the LFIA strip were 4.7 ng/g and 4.3 ng/g in tomato and green pepper, respectively. The results were obtained within 10 min. The average recoveries ranged between 95.4% and 109.6% with a coefficient of variation (CV) of 4.3% to 7.1% in tomato samples and between 94.8% and 109.1% with a CV of 3.9% to 6.1% in green pepper samples. These data suggested that our proposed LFIA is a sensitive, specific, and reliable method for the rapid detection of butralin in real samples.

Effective Sample Preparation of Polyphenols in Wine Using Deep Eutectic Solvent‐based Dispersive Liquid–Liquid Microextraction HPLC‐UV Determination

Polyphenols are phytochemicals that exist in grapes and are beneficial to human health. In this study, resveratrol, oxyresveratrol, and piceatannol in wine were extracted by deep eutectic solvent dispersive liquid–liquid microextraction (DES‐DLLME), and a method was established for quantifying these polyphenols by high‐performance liquid chromatography‐UV/Vis (HPLC‐UV/Vis). Several parameters pertaining to sample extraction, clean‐up, and concentration were optimized and verified with central composite design (CCD) using Design Expert 11. The optimized sample preparation parameters are as follows: the DES extraction solvent, tributylmethylammonium chloride/decanoic acid (1:3 M ratio); basic solvent, 1.3 mL of 5% potassium bicarbonate; volume of acetic anhydride, 250 μL; derivatization time, 5 min; dispersive solvent, methanol; ratio of extraction and dispersive solvents, 1:5.5; and salt, 1.0 g. Chromatographic separation by HPLC/UV–Vis was performed on an ACME C18 (4.6 mm id × 150 mm length, 5 μm particle size) column in gradient elution mode using water and 70% methanol. Under the established extraction and HPLC‐UV conditions, the limit of detection (LOD) and limit of quantitation (LOQ) of the three analytes in spiked samples ranged from 1.69 to 2.53 μg/L and 5.64 to 8.42 μg/L, respectively. Recovery studies were performed in low, medium, and high concentration ranges to establish a calibration curve, and the accuracy and precision in the working range were 95.1–108.0% and 1.3–6.7 RSD%, respectively. The calibration curves for quantitative analysis were obtained in the concentration ranges 5.6–56.4, 8.3–82.6, and 8.4–84.2 μg/L, with correlation coefficients (r2) ranging from 0.9947 to 0.9967. The proposed method was applied to the determination of polyphenols in wine samples.

Three–level simultaneous component analysis for analyzing the near–infrared spectra of aqueous solutions under multiple perturbations

Quantitative analysis under various perturbations is a difficult problem because the analytical signal changes with different factors. In this work, three–level simultaneous component analysis (3–MSCA) was used for analyzing the near–infrared (NIR) spectra of aqueous solutions under different perturbations. The spectral data of aqueous proline solutions at different pH, concentration and temperature were measured, and a three–level model was built to describe the effects of the three perturbations on the spectra, respectively. The first level model describes the change of the spectra with pH, from which significant aggregation of proline was observed around the isoelectric point. The second and third level model show the spectral change with concentration and temperature, respectively, and the spectral feature has a very good linear relationship with the corresponding influencing factors. Therefore, the pH and concentration scores can be used as the calibration curve for quantitative analysis of the pH and the content of proline, and the temperature scores can be used to predict the temperature of the solutions. In addition, the structural change of water molecules under different conditions is obtained from the loadings. A decline of the bulk water was found with the increase of concentration, implying an ascending trend of the bonded water due to the interaction of proline and water. The dissociation of water clusters with the increase of temperature is also displayed.

Self-diffusion of polycrystalline ice Ih under confining pressure: Hydrogen isotope analysis using 2-D Raman imaging

We have developed a high-resolution technique based on micro Raman spectroscopy to measure hydrogen isotope diffusion profiles in ice Ih. The calibration curve for quantitative analysis of deuterium in ice Ih was constructed using micro Raman spectroscopy. Diffusion experiments using diffusion couples composed of dense polycrystalline H2O and D2O ice were carried out under a gas confining pressure of 100MPa (to suppress micro-fracturing and pore formation) at temperatures from 235K to 245K and diffusion times from 0.2 to 94 hours. Two-dimensional deuterium profiles across the diffusion couples were determined by Raman imaging. The location of small spots of frost from room air could be detected from the shapes of the Raman bands of OH and OD stretching modes, which change because of the effect of the molar ratio of deuterium on the molecular coupling interaction. We emphasize the validity for screening the impurities utilizing the coupling interaction. Some recrystallization and grain boundary migration occurred in recovered diffusion couples, but analysis of two-dimensional diffusion profiles of regions not affected by grain boundary migration allowed us to measure a volume diffusivity for ice at 100MPa of (2.8±0.4)×10-3exp-57.0±15.4kJ/molRTm2/s (R is the gas constant, T is temperature). Based on ambient pressure diffusivity measurements by others, this value indicates a high (negative) activation volume for volume diffusivity of −29.5cm3/mol or more. We can also constrain the value of grain boundary diffusivity in ice at 100MPa to be <104 that of volume diffusivity.

Analysis of ethyl glucuronide and ethyl sulfate using aqueous normal-phase chromatography with mass spectrometry.

The use of aqueous normal-phase chromatography is explored as a possible format for the analysis of the forensically significant compounds ethyl glucuronide and ethyl sulfate. Standard solutions of the two compounds are used to verify the retention capabilities of two stationary phases (diamond hydride and undecanoic acid). These results are then compared to data obtained on hair extracts to determine if any matrix effects exist with respect to both retention and peak shape. The undecanoic stationary phase is used for the establishment of calibration curves for quantitative analysis. These curves are utilized to determine the concentration of ethyl glucuronide in several hair samples tested.

Comments on the paper: “Accurate quantitative analysis of gold alloys using multi-pulse laser-induced breakdown spectroscopy and a correlation-based calibration method”

The problem of finding new methods for the analysis of precious alloys has stimulated, in recent years, a number of different proposals for improving the analytical procedures introducing more robust calibration (or calibration-free) methods. In the paper “Accurate quantitative analysis of gold alloys using multi-pulse laser-induced breakdown spectroscopy and a correlation-based calibration method” by G. Galbács, N.Jedinski, G.Cseh, Z. Galbács and L. Túri [Spectrochimica Acta Part B, Volume 63, Issue 5, 591–597 (May 2008)] the authors proposed the use of multiple-pulse LIBS and a correlation-based method for building calibration curves for quantitative analysis of gold alloys. The method is proposed for gold alloys prepared using a fixed proportion of the alloying element. The general case where the relative concentration of the elements of the matrix is not a priori known is not discussed in the paper. In this communication, we will demonstrate that the method proposed is extremely fragile against matrix effects, and therefore cannot be usefully applied for the purpose of actual analytical measurements on gold alloys without a previous knowledge of the matrix composition.

Nondestructive analysis of the gold quarter liras

In this study, we have prepared seven Au-Cu standards in the concentration range of 18–24 (as carat) for nondestructive control of gold quarter liras. Some calibration curves for quantitative analysis of Au in the gold quarter liras that commercially present in Turkey have been plotted using these standard samples. The characteristic X-rays of Au and Cu emitted from these standard samples and the test sample with known composition are recorded by using a Ge(Li) detector. These calibration curves provide a nondestructive analysis of gold quarter liras with the uncertainties about 1.18%.

Microchip electrophoresis with hydrodynamic injection and waste-removing function for quantitative analysis

Quantitative analysis is problematic for microchip electrophoresis for several reasons including chip-to-chip variation, discontinuous sample re-loading, channel reconditioning, and electrokinetic injection bias. In this study, the capability for quantitative analysis on a flow-through based microchip electrophoresis, which provides continuous sample re-loading, channel washing, reconditioning and hydrodynamic injection as well as waste removing is demonstrated to be more quantifiable and more reproducible compared to manual electrokinetic injection method. Using the flow-through microchip with waste-removing function, FITC-labeled estrogen or Rhodamine B could be continuously analyzed without significant changes (R.S.D. < 6.6%) in signal intensity for over 3 h, which is sufficient for a complete set of quantitative analysis. With the use of a phosphorylated kinase substrate as the model, a calibration curve for quantitative analysis of phosphopeptides were constructed and results indicate that both R 2 value of the linearity and R.S.D. values of the peak intensity were around 0.9961 and 3.16%, respectively, without the use of an internal standard. These values were slightly improved to be around 0.9986 and 2.27%, respectively, with the use of a non-phosphopeptide counterpart as the internal standard. The potential of this flow-through device for the development of a kinase phosphorylation assay based on the quantitative method was also briefly discussed.

Capillary electrophoresis behavior of water-soluble anionic porphyrins in the presence of beta-cyclodextrin and its O-methylated derivatives.

The electrophoretic behavior of water-soluble anionic porphyrins, such as meso-tetrakis(4-carboxyphenyl) porphyrin (TCPP), meso-tetrakis(4-sulfonatophenyl) porphyrin (TSPP) and its zinc(II) and copper(II) complexes (ZnTSPP and CuTSPP, respectively) has been studied by capillary zone electrophoresis using fused-silica capillaries. The selectivity of the separation is strongly dependent on the type and concentration of betacyclodextrin (betaCD) or the O-methylated derivatives added to the background electrolyte. CuTSPP and TSPP can be separated using a pH 2.5 aqueous sodium phosphate buffer in the presence of 1 mM betaCD. Resolution is poorer or absent employing alkylated betaCDs, such as the heptakis (2,6-di-O-methyl)-beta-cyclodextrin or the heptakis(2,3,6-triO-methyl)-beta-cyclodextrin, as additives. On the other hand, separation of TSPP from its copper and zinc complexes has been achieved using a pH 7.0 aqueous sodium phosphate buffer, in the presence of 0.75 mM betaCD and 20% dimethyl sulfoxide (DMSO) as organic modifier. Under such conditions, the calibration curve for quantitative analysis of copper(II) was obtained. A rationale for the observed behavior will be presented and discussed on the basis of binding and protonation equilibria and a simple mathematical model.

Preparation of single phase bismuth-based 2212 and 2223 superconducting oxides, and quantitative X-ray diffraction analysis of 2212 and 2223 phase mixtures

The preparation of single phase superconducting BiSrCaCu oxide powders with the nominal structural formulae Bi 2Sr 2Ca 2Cu 3O 10 and Bi 2Sr 2CaCu 20 8 from precursor oxide and carbonate mixture compositions with or without lead doping is described. In the absence of lead doping it is found that precursor compositions ranging from the stoichiometric ratio for the 2212 phase to the stoichiometric ratio for the 2223 phase yield only the ‘80K’ 2212 phase superconductor according to X-ray diffraction analysis. To synthesise the ‘110K’ 2223 phase it is necessary to dope with lead and to use the non-stoichiometric precursor composition, corresponding to Bi 1.84Pb 0.34Sr 1.91Ca 2.03Cu 3.060 y, established by Koyama et al. If the carbonate sources of the strontium and calcium oxides, plus copper oxide, are precalcined together before being combined with the bismuth and lead oxides (following the method of Arendt et al.) and the mixture is then calcined using a modification of the Koyama procedure, single phase 2223 material is produced. X-ray diffraction spectra from powder mixtures containing known proportions of the 2212 and 2223 phases are used to construct intensity ratio calibration curves for quantitative analysis of samples containing the two compounds.

Quantitative analysis of carbide and intermetallic phases in Type 316 stainless steel by X-ray diffraction

Calibration curves for quantitative analysis by X-ray diffraction of precipitates in Type 316 stainless steel have been prepared using nearly “pure” M23C6 carbide and sigma phase. The method was checked by an independent technique using a Quantimet 720 Image Analysing Computer. Agreement of better than ±10% of the amount of precipitates was obtained between the two techniques.

Micro Fluorescent X-Ray Analyzer

AbstractA micro fluorescent X-ray analyzer with a focusing type of spectrometer has been developed to analyze samples of small amounts such as extracted inclusions or precipitates from metals or small areas in samples from 0.1 to 2.0 mm in diameter. This instrument is expected especially to analyze powder samples of small quantity because average values from such samples can be obtained and because surface conditions of the samples scarcely affect the results compared with their effect in electron probs microanalysis. A commercial X-ray tube is combined with a device of slits limiting incident X-rays, a focusing spectrometer with a Rowland circle of 4-in. radius, and a microscope of low magnification for observing the analyzing point on the samples. The wavelength range of the spectrometer with LiF and ADP analyzing crystals is from 1.20 to 9.94 Å, and, therefore, higher elements than aluminum in atomic number can be analyzed. The authors exerted their efforts to obtain the higher X-ray intensities in order to analyze smaller areas. The X-ray intensities obtained are satisfactory, except for light elements. For example, the detected X-ray intensity of pure nickel is 1650 cps with the use of a 0.1-mm diameter specimen, and that of pure sulfur is 52 cps with the use of a 0.1-ramdiameter specimen; however, with a 1-mm-diameter specimen, the intensity of pure nickel is over 5000 cps and that of pure sulfur is 1650 cps. These correspond to the intensities from 20-mm-diameter specimens of those elements when a flat-crystal spectrometer is used. The calibration curve for quantitative analysis generally varies with the sample area under analysis, but the same curves are obtained if the sample area is larger than 1 mm in diameter. Then, powder samples are analyzed quantitatively by using a plastic sample holder of 1-mm diameter and 0.3-mm depth. This instrument has good ability for microanalyzing trace elements by, for example, the ion-exchenge membrane method. The sensitivity represented is nearly 5000 cps/μg for Ni Kα from NiSO4 that is soaked and dried in thin rice paper. Some applications of the micro fluorescent X-ray analyzer to precipitates in steels and corrosion products are reported.

Quantitative determination of certain minerals in natural and artificial mixtures by DTA

Differential thermal analysis has been used in identifying individual minerals successfully; however, the use of DTA in identification of individual minerals in a mixture is not well accepted. This paper is divided into: introduction, terminology, history, derivation of the basic formula and thermograph. The various methods of determination are outlined and the advantages and disadvantages of each method discussed. Under separate-standard method the author considers the calibration curve method, the proportional method and the dilution method; the combined-standard method and the compensation-standard method are also treated. Piloyan concludes that the most reliable method is that of the calibration curve for quantitative analysis in a mixture, but this is contingent upon knowing the contained minerals to begin with. For poorly controlled experimental conditions the best results are obtained by using the combined-standard method. Advantages of DTA are the low cost of the apparatus, the fact that chemical analyses will not determine the minerals present. He also points out that DTA will not substitute for X-ray or chemical analyses but the three should be used in conjunction.—M.A. Klugman