Relative Error Of Determination Research Articles

DEVELOPMENT AND VALIDATION OF METHODS FOR QUANTITATIVE DETERMINATION OF TOFIZOPAM AND FENAZEPAM IN TABLETS METHOD OF HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY

Developed optimal conditions of quantitative analysis of tablets "Grandaxinum" and tablets "Fenazepam", using the method high-performance liquid chromatography. We used microcolony liquid chromatograph "milichrom A-02", condition analysis: gradient elution in the system lithium perchlorate, perchloric acid, water and acetonitrile, gradient linear 3700 mkl from 5 to 70 % at a flow rate of 100 mkl/min and a temperature of 40º C. Аs a standard substances were used pharmaceutical substance tofizopama and phenazepam. Conducted a validation assessment of the proposed conditions. The method is characterized by good linearity with the correlation coefficient at 0.9984 for tofizopama and 0,9991 for phenazepam in the concentration range of 0.025 – 0.5 mg/ml. the relative error of determination by the developed technique does not exceed of 1.94 %.

DP-sensors based on MF-4SC membrane and silica with hydrophobic surface for determination of phenylalanine, valine, and methionine cations

The influence of modification of MF-4SC membranes with silica (or surface-hydrophobized silica) nanoparticles on their ionic conductivity and diffusion permeability as well as the response stability and sensitivity of the membrane-based DP-sensors for cations of amino acids containing hydrophobic fragment has been studied. The membranes modified with surface-hydrophobized silica exhibited the 2–5 times reduced relative error of determination of the hydrophobic amino acids as compared to the initial membranes.

Selective photometric determination of low conentrations of selenium(IV) and selenium(VI) in bottled drinking water

A procedure is developed for the selective photometric determination of selenium(IV) in bottled drinking water by the oxidation of Methylene Blue in 1 M HCl to colorless decomposition products and of selenium(VI) by its interaction with the specified reagent at pH 5–6 with the formation of a colored ion pair. The limits of detection are 1 and 0.8 µg/L, respectively. At the concentration of selenium(IV) 2 µg/L, the admissible weight ratios are: SeO42-, Br3- (1: 20); Br– (1: 60); I–, IO3- and IO4- (1: 100). At equal concentration of selenium(VI), the following species: SeO42-(1: 20); Br3-, Br–, I–, IO3-, and IO4- (1: 100) do not interfere with the determination. Other anions and cations present in highly mineralized waters do not interfere with the determination. The relative error of determination is 8–10% in the concentration range 2–10 µg/L of selenium(IV) and selenium(VI) and does not exceed 5% in their concentration range of 10–100 µg/L.

ПРИМЕНЕНИЕ ПИКРИНОВОЙ КИСЛОТЫ ДЛЯ КОЛИЧЕСТВЕННОГО АНАЛИЗА ХАМАЗУЛЕНА В ЦВЕТКАХ MATRICARIA CHAMOMILLA

In this paper the standardization of raw of Matricaria chamomilla with application of picric acid is proposed. The technique of quantitative determination of chamazulene content in Matricaria chamomilla flowers with spectrophotometric method is developed. In the study of the absorption spectrum of an alcoholic solution of essential oil of Matricaria chamomilla after treatment by picric acid revealed that its maximum occurs at 657 nm and coincides with that of picrate chamazulene. The point at 657 nm is chosen as analytical wavelengths.Experiments are conducted of "added-found" method to assess the accuracy of the developed technique and found that the relative error no more than 3,5%. The relative error of determination in series of successive measurements is no more than 2,5%, and in series of parallel measurements – 5,5%. Metrological analysis showed that the method is accurate and reproducible. The quantitative determination of chamazulene content defined in 6 batches of industrial raw materials using the developed technique. The total of chamazulene content in Matricaria chamomilla flowers is between 8,49–20,05 mg%. The chamazulene content in Matricaria chamomilla flowers in terms of absolutely dry raw material should be at least 8 mg%.

PD-sensors based on perfluorinated membranes for simultaneous determination of vitamins B1, B6, and PP in aqueous solutions

The effect of the presence of bulky organic cations in the phase of perfluorosulfonated cationexchange membranes on the sensitivity of PD-sensors to ions of vitamins (nicotinic acid, pyridoxine, and thiamin) and hydronium in aqueous solutions has been studied. Three cross-sensitive PD-sensors based on perfluorinated membranes have been used for simultaneous determination of the ions of nicotinic acid, pyridoxine, and thiamine in aqueous solutions. The relative error of determination of the vitamins does not exceed 12%; the relative standard deviation of the determination results is no more than 0.04; the detection limit and the determination limit are 4.9 × 10−6 and 1.6 × 10−5 mol/L, respectively.

Determination of the alloying elements of nickel-based alloys designed for aviation application by inductively coupled plasma atomic emission spectrometry in combination with the microwave digestion method

A technique for determination of Al, Ti, Cr, Co, Nb, Mo, Ru, Ta, W, and Re in nickel-based alloys by inductively coupled plasma atomic emission spectrometry (ICP-AES) in combination with microwave digestion is described. The composition of the mixture used to dissolve the samples is formulated and the parameters of the microwave decomposition are adjusted. The relative error of determination of 0.1–20.00 wt % of elements does not exceed 4%.

Mathematical Model of Kinetics of Antigens Accumulation in the Process of Periodical Submerged Cultivation of <I>Vibrio cholerae </I>569В Inaba with Limitation as Regards Carbonic Substrate

Presented is mathematical model of kinetics of the process of O-antigen and cholera toxin synthesis during periodical submerged cultivation of V. cholerae 569В Inaba with limitation as regards carbonic substrate. The proposed model is based upon analysis of experimental data on V. cholerae 569В Inaba biomass and antigens accumulation, rate of growth and antigens release, and glucose utilization. Using Mathcad 15.0 software calculated are coefficients of differential equations entering into the mathematical model. Comparison of predicted and experimental data demonstrates that relative error of determination of concentrations of the synthesized substances, glucose and cholera vibrio is between 5 and 20 %. The proposed model permits to determine maximum output of final products and specify the parameters of cultivation process performance at different initial conditions.

Determination of polyphenolic compounds in Cirsium palustre (L.) extracts by high performance liquid chromatography with chemiluminescence detection

The first method for the simultaneous determination of polyphenolic antioxidants in extracts from leaves of Cirsium palustre based on high performance liquid chromatography combined with flow injection chemiluminescence detection (HPLC-FI-CL) has been developed. The extracts were prepared by using methanol as extraction medium and two types of extraction methods (reflux and ultrasound assisted extraction). The post-column CL determination of polyphenols was based on their enhancing effect on the chemiluminescence intensity generated in manganese(IV)–hexametaphosphate–formaldehyde system in a phosphoric acid medium. Main antioxidants determined in C. palustre leaves were eriodictyol-7-O-glucoside, luteolin-7-O-glucoside and 6-hydroxyluteolin-7-O-glucoside belonging to flavonoids, and chlorogenic acid belonging to phenolic acids. Chromatographic separation was carried out on a C18 column with gradient elution by using a mobile phase containing 0.25% (v/v) phosphoric acid in water (solvent A) and 100% methanol (solvent B). Under the optimized conditions of chromatographic separation and CL detection the validation of the method was performed. The calibration curves showed good linearity in the concentration range from 0.5 to 40µgmL−1. The HPLC-FI-CL method was successfully applied to the determination of four polyphenolic compounds in methanolic extracts from leaves of C. palustre. The accuracy of the developed method was confirmed by the comparison of the results with those obtained by an HPLC-PDA method. The relative error of determination does not exceed 6.1%. However, the HPLC-FI-CL method is characterized by 40–65 times higher sensitivity compared to the HPLC-PDA method.

Extraction-spectrophotometric determination of selenium in organoselenium compounds using aromatic o-diamines

Procedures for the extraction-spectrophotometric determination of selenium in organoselenium compounds using a new reagent, 1,2-diamino-3,4,5,6-tetrafluorobenzene (DAFB), and a known reagent, 2,3-diaminonaphthalene (DAN), are developed. Complexes of DAFB or DAN with selenium(IV) are extracted with toluene, and the absorbance of the extracts is measured. The optimal conditions for the determination were found, and the spectrophotometric characteristics were determined. The calibration curves are linear in the range of selenium concentrations of 1–10.6 mg/L (DAFB) and 1–9.1 mg/L (DAN). Nitrogen, chlorine, bromine, fluorine, and sulfur present in organoselenium compounds do not interfere with the determination of selenium. The relative error of determination does not exceed ±2%.

Features of the determination of photosynthetic pigments in peats of different genesis

The paper represents the results on working out spectrophotometric procedure for determination of photosynthetic pigments in peat samples of different origin. According to the results of implementation of this technique at conditions of inter-laboratory precision; relative error in determination of chlorophyll "a" does not exceed 20%; chlorophyll «b» - 32%.

Extraction-photometric selective determination of trace perchlorates in potable waters

A method is proposed for the selective photometry determination of perchlorates in potable water with a detection limit of 2×10−3 mg/L is proposed based on the extraction of its ion pair with the astrafloxin cation and absorbance measurements at 540 nm. The following ratios of matrix ions are acceptable (in parentheses): ClO−, ClO2−, ClO3−, BrO3− (500); I− (1000); IO3− (7000); HCO3−, Cl−,SO42−, NO3−, Br−, Na+, K+, Ca2+, Mg2+ (10000). The relative error of determination for ClO4− is 20% in the range 4 × 10-3-1 × 10−2 mg/L and 10% in the range 1 × 10-2–5 × 10−2 mg/L.

Seismic characterization of naturally fractured reservoirs using amplitude versus offset and azimuth analysis

ABSTRACTP‐wave seismic reflection data, with variable offset and azimuth, acquired over a fractured reservoir can theoretically be inverted for the effective compliance of the fractures. The total effective compliance of a fractured rock, which is described using second‐ and fourth‐rank fracture tensors, can be represented as background compliance plus additional compliance due to fractures. Assuming monoclinic or orthotropic symmetry (which take into account layering and multiple fracture sets), the components of the effective second‐ and fourth‐rank fracture compliance tensors can be used as attributes related to the characteristics of the fractured medium. Synthetic tests indicate that using a priori knowledge of the properties of the unfractured medium, the inversion can be effective on noisy data, with S/N on the order of 2. Monte Carlo simulation was used to test the effect of uncertainties in the a priori information about elastic properties of unfractured rock. Two cases were considered with Wide Azimuth (WAZ) and Narrow Azimuth (NAZ) reflection data and assuming that the fractures have rotationally invariant shear compliance. The relative errors in determination of the components of the fourth‐rank tensor are substantially larger compared to the second‐rank tensor, under the same assumptions.Elastic properties of background media, consisting in horizontal layers without fractures, do not cause azimuthal changes in the reflection coefficient variation with offset. Thus, due to the different nature of these properties compared to fracture tensor components (which cause azimuthal anomalies), simultaneous inversion for background isotropic properties and fracture tensor components requires additional constraints.Singular value decomposition (SVD) and resolution matrix analysis can be used to predict fracture inversion efficacy before acquiring data. Therefore, they can be used to determine the optimal seismic survey design for inversion of fracture parameters. However, results of synthetic inversion in some cases are not consistent with resolution matrix results and resolution matrix results are reliable only after one can see a consistent and robust behaviour in inversion of synthetics with different noise levels.

Экстракционно-хроматографическое определение местных анестетиков в водных средах

The extraction novocaine, lidocaine anestezina are studied from aqueous media by individual organic solvents (aliphatic alcohols, normal and isomeric structure of C 3 – C 9 alkylacetates C 2 – C 5 ) and their mixtures using of different salting-out agents (chlorides, sulfates, sodium and ammonium). The coefficients of the distribution and the degree of extraction of anesthetics are calculated. It is shown that with increasing number of carbon atoms in the molecules of alcohols and esters their extractant possibility is decreased and alcohols isomers are less effective than normal ones. For the most complete extraction of the anesthetics the mixtures of alcohols with isomeric structure and alkyl acetates are used. Two and ternary-component mobile phase at chromatography in thin layer are studied for separation of local anesthetics in the concentrates, the mobility coefficients of substances are calculated. Quantitative evaluation are carried out by application of specialized software. The separation coefficients of anesthetics are calculated. The technique of determination of analytes in aqueous media is developed. The results of the extraction- chromatographic determination of novocaine, lidocaine and anaesthesin in aqueous media are proved by method «introduced – found». The range of detectable concentrations is 0.1 – 1 mkg/sm 3 , detection limit is 0.02 mkg/sm 3 . The relative error of determination is less than 10 %. Keywords : local anesthetics, extraction, chromatography in a thin layer (Russian) DOI: http://dx.doi.org/10.15826/analitika.2013.17.4.013 Ia . I . Korenman , T . V . Chibisova , P . T . Sukhanov , M.V. Zybenko Federal State Budget Educational Institution of Higher Professional Education «Voronezh State University of Engineering Technologies» (FSBEI HPE «VSUET») , Voronezh, Russian Federation

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.

Potentiometric electronic tongue to resolve mixtures of sulfide and perchlorate anions.

This work describes the use of an array of potentiometric sensors and an artificial neural network response model to determine perchlorate and sulfide ions in polluted waters, by what is known as an electronic tongue. Sensors used have been all-solid-state PVC membrane selective electrodes, where their ionophores were different metal-phtalocyanine complexes with specific and anion generic responses. The study case illustrates the potential use of electronic tongues in the quantification of mixtures when interfering effects need to be counterbalanced: relative errors in determination of individual ions can be decreased typically from 25% to less than 5%, if compared to the use of a single proposed ion-selective electrode.

Metrological support for the ASKRO spectrometric channel

The metrological support for monitoring of ground layer of the atmosphere with ASKRO gamma spectrometers requires determining their sensitivity in the measurement geometry of technogenic radionuclides. The application of numerical modeling, the method of similarity of radiation fields, and a combined method in evaluating sensitivity of a spectrometer is examined. It is shown that the model method overstates the sensitivity and does not permit checking the spectrometer. To decrease the error of estimation a combination of measurements of the efficiency of the spectrometer for a point source and a Monte Carlo calculation of the incident flux is used. An estimate of the total relative error of determination of the sensitivity is given and it is shown that it can be verified. The estimates obtained for the sensitivity increase the minimum measured volume activity of the spectrometer at energies less than 1 MeV.

Electrothermal atomic-absorption determination of copper and zinc in mineral waters and peloids

The article presents the results of electrothermal atomic-absorption determination of copper and zinc in mineral waters and peloids.1 The article contains metrological control of the techniques and confirms the possibility of their use during the analysis of these natural objects. The detection limit of copper and zinc constitutes respectively 0.6 ad 0.7 μg/dm3, relative error of determination being ± 0.05 and ± 0.03.

Quantitative determination of total triterpenoid saponins in Polemonium caeruleum rhizomes and roots

A spectrophotometric method of quantitative determination of total triterpenoid saponins in rhizomes and roots of Polemonium caeruleum is developed. The procedure does not require sandard samples. The standard relative error of determination does not exceed 4.88%. The proposed procedure is recommended for analysis of the raw material and ready-to-use medicinals based on Polemonium caeruleum.

Two-stage extraction preconcentration and HPLC determination of phenol and 1-naphthol in aqueous solutions

The extraction of phenol and 1-naphthol with isomolar mixtures of ethyl acetate and hexane under batch conditions and with tributyl phosphate impregnated into a polyurethane foam under batch and dynamic conditions was studied. A procedure for determining phenol and 1-naphthol in aqueous samples was developed including their dynamic recovery on a column packed with polyurethane foam impregnated with tributyl phosphate, elution with a 0.1 M NaCl solution of pH 12.5–13.0, extraction with a mixture of ethyl acetate and hexane, and separation by normal-phase high-performance liquid chromatography (HPLC) with UV-detection. The overall preconcentration coefficient was 250. The detection limits were 2.5 μg/L. The relative error of determination was lower than 18%. The time of one determination was 2–2.5 h.

Model calculations of the total electron count for the GPS satellites system

[1] The global numerical model of the thermosphere, ionosphere, and protonosphere of the Earth, making it possible to calculate all the main parameters of the near-Earth plasma, is used to calculate the total electron content (TEC). The calculations are performed along the ray of the signal propagation between the ground-based reception point and a GPS system satellite. The values of TEC calculated according to satellite data are compared with the “true model” value of TEC for magnetically quiet conditions of the spring equinox at moderate solar activity. Relative errors in determination of the satellite TEC for two European stations Brest (48.5 N, 5.5 W) and Kaliningrad (55 N, 20 E) are calculated. It is demonstrated that an increase of the number of the observed satellites does not always lead to an increase of the accuracy of the TEC measured with the help of the satellites. INDEX TERMS: 2494 Ionosphere: Instruments and techniques; 2481 Ionosphere: Topside ionosphere; 2447 Ionosphere: Modeling and forecasting; KEYWORDS: Ionospheric modeling; GPS system; total electron content.