Analitika i Kontrol最新文献

{"title":"Important features of retention indices determination in reversed-phase high performance liquid chromatography","authors":"I. Zenkevich, A. Derouiche, D. Nikitina","doi":"10.15826/analitika.2022.26.1.007","DOIUrl":"https://doi.org/10.15826/analitika.2022.26.1.007","url":null,"abstract":"The features of the retention indices determination in reversed phase high perfor­mance liquid chromatography (RP HPLC) are discussed, namely the different possibilities of the application of the recurrent relations. At first, not the experimental, but the precalculated values are recommended as the retention parameters of non-sorbable compound (dead time, t0) in RP HPLC. It is because just the precalculated values provide the linearity of rela­tionships lg (tR – t0) = anC + b, where nC is the number of carbon atoms in molecules of ho­mologs selected as reference compounds (n-alkyl phenyl ketones). Besides the known Peterson and Hirsch equation for the theoretical evaluation of t0 using the retention times of three consecutive homologs, the following recurrent relations are also recommended: tR(nС – 1) = atR(nC) + b, from where it follows that t0 = lim (tR)½(nC ® 0) = b / (1 – a) under the condition that 0 < a < 1. Another area of the effective application of the recurrent relations is caused by the following fact: the ranges of the concentrations of the eluent’s organic constituents during the separation of hydrophilic analytes and hydrophobic reference n-alkyl phenyl ketones may not overlap, or over­lap only partially. In such cases, expanding the data arrays seems to be reasonable using the extrapolated values both for the target analytes, and (preferably) for the reference compo­unds. For these purposes, another kind of recurrent relations can be recommended, name­ly tR(C ± DC) = atR(C) + b, DC = const. All recommendations on the application of recurrent relations in RP HPLC are illustrated with examples.","PeriodicalId":37743,"journal":{"name":"Analitika i Kontrol","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67254739","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"THEOBROMINE AND THEOPHYLLINE DETERMINATION IN BLACK TEA BY CAPILLARY ZONE ELECTROPHORESIS USING LARGE VOLUME SAMPLE STACKING","authors":"E. Tishchenko, T. Tsiupko, I. E. Zhuravleva","doi":"10.15826/analitika.2022.26.4.003","DOIUrl":"https://doi.org/10.15826/analitika.2022.26.4.003","url":null,"abstract":"Some features of the formation of methylxanthines during growth and development of tea leaves are discussed, and the information about the content of minor methylxanthines, theobromine (TB) and theophylline (TF), in tea products is summarized. The expediency of using TB and TF as marker substances characterizing the quality of tea is substantiated. Possibility and limitations of using electrophoretic methods for TB and TF determination in tea products were investigated. Experimental studies were carried out to develop a method for TB and TF determination in black tea by capillary zone electrophoresis using the procedure of analytes online concentration – large volume sample stacking (LVSS-CZE-UV). Optimized conditions for the analytes separation were using the borate buffer solution (pH = 9.8, 90 mM concentration) and 20 kV voltage in the system. The following conditions for the analytes concentrating were proposed: time for introducing a 40-fold diluted tea extract (1.0 g per 100 ml of water) was 200 s at 50 mbar; the polarity reversal time was 1.5–1.7 min at a voltage of –10 kV. Under the selected conditions, the TB and TF concentration efficiency factors were 28 and 38, respectively. The analysis time did not exceed 22 min. For the developed method, the repeatability, intralaboratory precision, trueness and accuracy of the results of analytes determination in black tea samples were evaluated. Determining TB (0.04–4.0 mg/g concentration range) and TF (0.04–1.0 mg/g concentration range) in tea showed that the relative standard deviation of the results of the analytes determination σ(Δ) did not exceed 7 and 12 %, respectively. Analysis of various samples of black tea using the developed method showed that TB content ranged from 0.14 to 2.32 mg/g and TF content ranged from \"< 0.040\" to 0.15 mg/g.","PeriodicalId":37743,"journal":{"name":"Analitika i Kontrol","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67255023","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Using equilibrium thermodynamics to study thermochemical processes in arc discharges used in atomic emission spectral analysis (review)","authors":"A. Pupyshev","doi":"10.15826/analitika.2022.26.2.003","DOIUrl":"https://doi.org/10.15826/analitika.2022.26.2.003","url":null,"abstract":"Until the beginning of the 21st century, the arc discharge was the main source of excitation of the atomic spectra of elements during routine atomic emission spectral analysis. The wide application of this spectral source at the same time aroused great interest of analysts in the study of complex thermochemical processes occurring at its electrodes and in the discharge plasma. This was due to the need to improve the metrological and informational characteristics of the analysis. Equilibrium thermodynamics has often been used to carry out such studies. It is shown that three levels of the thermodynamic approach can be distinguished here, differing in the complexity of the applied apparatus of thermodynamics and the information content of the results obtained. Numerous examples of the application of these levels of approach to the study of thermochemical processes occurring in the electrode or in the discharge plasma are given. The main advantages and disadvantages of the approaches used, which provide only qualitative information about the ongoing processes, are noted. The main disadvantage is the impossibility of predicting the composition of the arc plasma from the initial composition of the condensed sample. The most informative is the generalized thermodynamic model of thermochemical processes in a DC arc discharge from the sample surface and from the electrode crater. The model is based on the division of a non-stationary non-equilibrium system of an arc discharge into successive quasi-stationary subsystems. They correspond to the stage of sample evaporation and thermochemical transformation of its components in the discharge plasma. According to the model, the total equilibrium composition of the evaporated sample is initially calculated. This determines the initial composition of the arc plasma. Then, the total equilibrium composition of the arc plasma is calculated and the transition to the intensities of the spectral lines of the analytes is performed. The correctness of the generalized model, which gives semi-quantitative results, is confirmed by comparison with experimental data.","PeriodicalId":37743,"journal":{"name":"Analitika i Kontrol","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67255189","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Voltammetric and sequential injection amperometric determination of B group vitamins on electrodes modified with binary systems based on oxides of manganese, bismuth and gold","authors":"L. G. Shaidarova, I. Chelnokova, I. Gafiatova, A. V. Gedmina, H. Budnikov","doi":"10.15826/analitika.2022.26.4.001","DOIUrl":"https://doi.org/10.15826/analitika.2022.26.4.001","url":null,"abstract":"It was found that oxides of manganese (MnOx), bismuth (ВiOx), gold (AuOx), and ВiOx–MnOx and MnOx–AuOx binary systems electrodeposited on the surface of planar carbon electrodes (SPE) exhibited catalytic activity during electrooxidation of thiamine, riboflavin, pyridoxine and cyanocobalamin in acidic media. Immobilization of the binary systems on the surface of the SPE working electrode allowed to achieve a joint selective voltammetric determination of two-component systems of the vitamins considered: riboflavin and pyridoxine on SPE with BiOx–MnOx (ВiOx–MnOx–SPE) and MnOx–AuOx (MnOx–AuOx–SPE); and riboflavin and thiamine or riboflavin and cyanocobalamin on MnOx–AuOx–SPE. The calibration dependences obtained for the considered vitamins using voltammetry on BiOx–MnOx–SPE and MnOx–AuOx–SPE electrodes were observed in the range from 1×10–6 to 1×10–3 M. Detection limit of thiamine, pyridoxine and cyanocobalamin was decreased by an order of magnitude compare to static conditions in a sequential injection system (SI-system). To implement two- and three-component analysis of biologically active additives (BAA) and drugs in the SI-system, the surface of the working electrode modified with MnOx–AuOx binary system was covered with poly-2-vinylpyridine (PVP) or Nafion (Nf) polymer films. SPE with two working electrodes (DSPE) modifies with MnOx–AuOx were used in the two-component analysis of BAA samples. PVP film was deposited on the electrode for thiamine determination and Nf film was deposited on the electrode for pyridoxine determination. Combination of SPE and DSPE with polymer composites containing MnOx–AuOx binary system and PVP or Nf in a two-detector SI-system made it possible to implement a three-component analysis of drugs containing thiamine, pyridoxine and cyanocobalamin. Excipients present in them did not interfere with the results of the determination. Application of the proposed SI-system scheme increased selectivity, speed and productivity of the analysis to 540 determinations per hour.","PeriodicalId":37743,"journal":{"name":"Analitika i Kontrol","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67255485","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Capabilities and limitations of tin direct determination using the spectrometry methods with inductively coupled plasma in Azov and Black sea waters","authors":"D. Abakumova, Z. Temerdashev, P. Abakumov","doi":"10.15826/analitika.2021.25.2.007","DOIUrl":"https://doi.org/10.15826/analitika.2021.25.2.007","url":null,"abstract":"The current study discussed the capabilities and limitations of tin direct determination in the waters of the Black and Azov Seas using the ICP-MS and ICP-AES methods without the separation and concentration of the analyte. The conditions for the analysis of waters, the influence of dilution and matrix components on the results of the analysis were established. As the salinity of the seawater increased, the slope of the calibration curve decreased, regardless of the detection method used. The leveling of the matrix effect of seawater on the analytical signal of tin was achieved by diluting the sample up to 100 times. A significant decrease in the analytical signal of tin was observed on the samples of seawater characterized by the high salinity. These methods allowed determining tin at the concentrations ranging from 0.33 μg/dm3 (ICP-MS), 0.37 μg/dm3 (ICP-AES) to 5 μg/dm3 in natural (fresh) water or seawater with low salinity level according to the calibration curve of the deionized water. For ICP-MS and ICP-AES determination of tin in seawater with the salinity level above 6‰ and tin concentration of more than 5 μg/dm3, it was required to use the calibration dependence constructed on the model seawater considering the salinity of the object. The studies have shown that the content of tin in the Kuban River is 0.13 μg/dm3. In the Sea of Azov, the concentration of tin in the water, depending on the sampling site, was less than 0.33 μg/dm3 (Taman) and 1.8 μg/dm3 (Temryuk, commercial port). In the Black Sea, the concentration of tin in the seawater samples from Novorossiysk city was higher and ranged from 0.55 μg/dm3 (embankment) to 1.5 μg/dm3 (seaport) and 2.1 μg/dm3 (grain terminal).","PeriodicalId":37743,"journal":{"name":"Analitika i Kontrol","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48527287","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Determination of formaldehyde in production solutions using the piezoelectric sensors","authors":"A. A. Merenkova, K. Zhuzhukin, A. N. Zyablov, L. Belchinskaya","doi":"10.15826/analitika.2021.25.2.003","DOIUrl":"https://doi.org/10.15826/analitika.2021.25.2.003","url":null,"abstract":"In the current work, piezoelectric sensors based on a molecular imprinted polymer (MIP) were obtained for determining the formaldehyde in the industrial solutions of a woodworking plant. The synthesis was carried out directly on the surface of the piezoelectric sensor. In the process of the two-stage thermoimidization of the obtained prepolymerization mixture, a molecular imprinted polyimide of formaldehyde was formed. For the analysis of the supra-resin part of the effluent of the Grafskaya kuhnya LLC (Voronezh) woodworking enterprise, which was obtained by the dry distillation of wood, the method of a calibration graph having a linear relationship was used; the coefficient of determination R2 = 0.97. The detection limit of the piezosensor was 0.6 ∙ 10–4 mol / dm3, the range of determined concentrations was 1.0 – 10–4 mol / dm3. The comparison of piezoelectric sensors based on the polymer without imprints and based on the polymer with imprints of formaldehyde showed high selectivity of the latter for the target molecule. The calculated imprinting factor was 28.3, the coefficient of selectivity with respect to phenol was 0.05, which indicated the selectivity of the modified sensor to formaldehyde. The verification of the correctness of the determination of formaldehyde in the model and production solutions was carried out using the \"added-found\" method. It was found that the MIP-based sensor was sensitive only to formaldehyde, the relative standard deviation did not exceed 2.0%. In order to assess the effect of the object matrix (formaldehyde) on the value of the resonant frequency, the standard addition method was used. It was determined that the matrix did not affect the value of the analytical signal, the relative standard deviation was 2.8%. For the re-analysis, the piezoelectric sensor was exposed to the regeneration in the oven at 50 ⁰С. The proposed method for determining the concentration of the formaldehyde using the MIP-sensor allowed controlling the content of the toxicant in the industrial solutions.","PeriodicalId":37743,"journal":{"name":"Analitika i Kontrol","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49606558","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"X-ray spectral analysis development in Novosibirsk city (Electron probe microanalysis and X-ray fluorescence analysis using the synchrotron radiation)","authors":"A. Revenko","doi":"10.15826/analitika.2021.25.2.006","DOIUrl":"https://doi.org/10.15826/analitika.2021.25.2.006","url":null,"abstract":"Current article considers the contribution of X-ray physicists from the city of Novosibirsk to the formation and development of the two X-ray spectral analysis directions: electron probe microanalysis and X-ray fluorescence analysis using the synchrotron radiation. The research on geological topics at the Institute of Geology and Geophysics of the Siberian Branch of the USSR Academy of Sciences using the MS-46 electron probe microanalyzer of the French company CAMECA (since 1967) served as the basis for the development of methods for the quantitative X-ray microanalysis of rock-forming minerals as the methods for quantitative determination of the contents of elements with low atomic numbers in the long-wavelength X-ray region were still in their infancy. With the development and the improvement of the method’s technical base (microprobes JXA-5A, JEOL, 1975; Kamebaks Micro, CAMECA, 1981; JXA-8100, JEOL, 2003; JXA-8230, JEOL, 2016; electronic computing), the software for controlling the operation of devices and converting the measured intensities of the analytical lines into the concentration of elements continued to changed and improve. The first results of elemental analysis, obtained using the synchrotron radiation to excite X-ray fluorescence at the VEPP-3 accelerating ring at the Institute of Nuclear Physics of the Siberian Branch of the USSR Academy of Sciences, were published in1977. Inthe following years, at the station of elemental SRXRF, samples of various nature were studied — biological (bio tissues of the heart, liver, lungs, hairs, bones, plants), geological, environmental objects (soils, sediments, aerosols, etc.), archaeological sites as well as new technological materials. The procedures for the determination of chemical elements in low-mass samples (milligrams) in unique samples of lunar soil samples, biopsy material of human myocardial tissues, etc. have been developed. The scanning device at the elemental SRXRF station made it possible to obtain the information for reconstructing the climate change for different periods of time – from 100 to 1000 years. A new non-destructive method of confocal X-ray microscopy for studying micro-objects and visualizing the distribution of chemical elements in extended objects on this station are currently being developed.","PeriodicalId":37743,"journal":{"name":"Analitika i Kontrol","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67253360","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Dynamic-range extension of MAES multichannel analyzers based on BLPP-2000 and BLPP 4000 photodetector arrays","authors":"S. Babin, V. А. Labusov, D. O. Selyunin, O. V. Pelipasov","doi":"10.15826/analitika.2021.25.4.011","DOIUrl":"https://doi.org/10.15826/analitika.2021.25.4.011","url":null,"abstract":"One trend in the development of integral atomic emission spectral analysis with low spectral background excitation sources, such as inductively coupled or microwave plasma, is to increase the dynamic range of spectrum recording systems based on photodetector arrays. To achieve low detection limits, it is necessary to use photodetector arrays with low reading noise. The dynamic range of a single readout of such photodetector arrays usually does not exceed four orders of magnitude. The dynamic range increase due to the accumulation of spectra from multiple acquisition leads to a quadratic increase in the measurement time. This method does not allow one to cover the entire dynamic range of spectral line intensities of inductively coupled or microwave plasma (which can reach seven orders of magnitude) while maintaining an acceptable total measurement time of a sample spectrum. As an alternative, it is proposed to increase the dynamic range toward higher line intensities by using two different alternating accumulation times during measurement. The objective of this study is to implement the proposed recording mode in MAES analyzers based on BLPP-2000 and BLPP-4000 photodetector arrays in order to increase the dynamic range of recorded spectral lines. Dependences of the signal-to-noise ratio and the dynamic range of spectral lines recorded in integral atomic emission spectrometry on the accumulation time, the total measurement time, the spectral background level, and the photodetector array parameters are obtained. It is shown theoretically that the use of the recording mode with alternating different accumulation times should increase the dynamic range of BLPP-2000 and BLPP-4000 photodetector arrays by two orders of magnitude. The dynamic range of spectral line intensities of a hollow-cathode lamp is shown experimentally to increase by two orders of magnitude (to five orders of magnitude).","PeriodicalId":37743,"journal":{"name":"Analitika i Kontrol","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67254281","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Bilayer capillary coatings based on nanosized ion-exchangers for the capillary electrochromatography analyses of biogenic amines and amino acids","authors":"D. Makeeva, D. Polikarpova, L. Kartsova","doi":"10.15826/analitika.2021.25.3.004","DOIUrl":"https://doi.org/10.15826/analitika.2021.25.3.004","url":null,"abstract":"Nanoparticles are widely used in capillary electrophoresis as stationary phases adsorbed on the internal capillary walls for the separation and concentration of analytes in capillary electrochromatography. The fastest and simplest approach for the formation of coatings is a physical adsorption of nanoparticles. Nevertheless, the formed coatings frequently possess low stability. The layer-by-layer approach for the formation of stabile and dense coating of internal capillary walls based on negatively charged nanosized cation-exchanger was proposed. The method included the sequential alteration of appositively charged layers of nanosized ion-exchangers. The proposed “anion-exchanger – cation-exchanger” bilayer coating possesses high stability in wide pH range (2-10) and provides up to 120 analyses without the need of re-coating. The coating was applied for the separation and on-line concentration of catecholamines and amino acids in capillary electrochromatography mode. High efficiencies were achieved (N = 450-720 th. t.p./m and N = 400-520 th. t.p./m for cathecholamies and amino acids, respectively), while the analysis time was significantly decreased. It was established, that high concentration of negatively charged functional groups on the capillary surface led to the increase of stacking efficiency factors due to the interactions between analytes and functional groups of the modifier on the capillary walls. It contributed to the 2-4 times reduced detection limits (LODs) of analytes compared to the mono-layer coatings (LODs of catecholamines = 3-4 ng/mL, LODs of amino acids = 40-100 ng/mL).","PeriodicalId":37743,"journal":{"name":"Analitika i Kontrol","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67253130","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comparative characterization of different kinds of chromatographic quantification using the double standard addition method","authors":"I. Zenkevich, Darina Barkhatova, Maria Belysheva, N. A. Kaminskii, Elizabet M. Karchuganova, Anastasia V. Klaving, Alexander A. Kovalenko, Vasilisa Krivovicheva, Artem A. Kuz’min, M. V. Mel’nik, Polina Paramonova, R. Popov, Vassylii V. Potapenkov, A. A. Rashevskii, Alexandra A. Sysoeva, Irina I. Fedorova, A. A. Firsov","doi":"10.15826/analitika.2021.25.2.010","DOIUrl":"https://doi.org/10.15826/analitika.2021.25.2.010","url":null,"abstract":"Different algorithms for processing the quantitative gas chromato­gra­­phic ana­lysis data using the double standard addition method are compared for their accuracy. Three principal approaches are possible for such processing: I – simple comparison of values determined by sing­le and double standard additions, II – approximation of «peak area of ana­lyte» (S) – «mass of standard addition» (madd) depen­den­ce by the least squa­res method [linear reg­res­sion, m(S)], and III – independent quantification of analyte with both standard additi­ons follo­wed by the linear extrapolation of two sub-results on the so-cal­led «zero standard addi­tion», mx(madd ® 0). It is concluded that the quantitation results obtained using the various modes of the method are comparable in accuracy, but somewhat underestimated relative to the specified amounts of analytes. The principal reason of such systematic errors is the eva­po­ration of the solvent during the successive injecting of the same samples into the gas chroma­to­graph. Due to this reason the peak are­as, measured after the standard addition, appear to be slight­­ly increased and this leads to the systematic underestimation of the results. The second (less impor­tant) factor is the small increa­se of the samp­le volumes due to the addition of the compo­nents to be determined. It is confirmed that the systematic errors of different modes of standard addition are not exceeding the values of their random uncertainties. The op­ti­mal results (considering their signs of deviations) are provided using the double standard addition method with extrapolation of sub-results on «zero standard addition». In order to exclude the possible influence of «human factor» (increasing the re­sults precision during the series of analyses of similar samples due to the rising experience of analytical chemists) all parallel measurements have been per­for­med by bachelor students of the Chemistry Ins­titute of the St. Petersburg State University in the course of their laboratory practical works in chromatography. Such organization of experiments increases their credibility as it excluded the dependence of the results on the qualification of chemists.","PeriodicalId":37743,"journal":{"name":"Analitika i Kontrol","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67253432","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}