Ion Chromatographic Method Research Articles

Separation of fluoride in the presence of large amounts of organic acids by ion chromatography

ABSTRACT An ion chromatography (IC) method for the separation of fluoride in presence of large concentrations of organic acid anions was developed with a view to determine trace level concentration of fluoride in plant samples. Present study deals with determination of fluoride in dry black gram seeds. Pyrohydrolysis was employed for extracting fluoride from the seeds. Organic acid anions are produced during pyrohydrolysis of seeds/plant materials and these organic anions show similar retention behavior of fluoride in IC. Separation of fluoride from organic acids and common anions was investigated. An IC method involving the appropriate dilution of pyrohydrolysis distillate of the sample followed by a large volume injection through a pre-concentrator column is proposed to circumvent the interference due to organic acids. Fluoride recovery of the pre-concentrator column is found to be more than 90%. The method provides a precision better than 7% (RSD). The limit of detection of the method is 0.5ppmw whereas the LOD for fluoride by IC method alone is 10 ppb. Results obtained are validated by analyzing the samples by using fluoride ion selective electrode method.

Simultaneous determination of flouride, iodate and iodide by ion chromatography in caustic off-gas scrubber of nuclear recycle facilities by employing dual detectors

ABSTRACT An ion chromatography method was developed for the simultaneous determination of fluoride, iodate and iodide in a caustic scrubber solution used for trapping off-gases released during the dissolution of nuclear fuels. A separation between iodate and fluoride could be realized with 0.6 mM hydroxide, which is too weak to elute other anions including iodide in reasonable time. Studies were carried out at different column temperature, and with the help of Van’t Hoff plots the thermodynamic parameters associated with the column equilibrium were estimated, which helped in understanding the co-elution of iodate and fluoride at higher concentration of eluent. An arrangement of conductivity detector and UV-VIS detector in sequence after the ion exchange column (with 15 mM NaOH as eluent) was used for recording chromatograms for conductivity signal and UV-VIS signal simultaneously. The information from the two chromatograms was utilized to quantify iodate, fluoride and iodide in a single run. The limit of detection for fluoride, iodate and iodide is 7 ppb, 10 ppb and 12 ppb, respectively. The precision of the method is better than 2% (RSD) at 0.5 mg/L. The method was used successfully for the real sample analysis.

Небезпечні хлорити у питній воді: утворення та видалення при використанні діоксиду хлору в технології водопідготовки

The aim of the work was to study the features of the formation and removal of toxic chlorites at the treatment facilities of the Dnipro water pipeline in Kiev, where chlorine dioxide is used in water treatment technology, and the influence of priority natural and technological factors on these processes. Materials and methods. The studies were carried out in 2021-2022. at the Dnipro waterworks in Kyiv, where chlorine dioxide is used instead of chlorine in water treatment technology. We have analyzed the data of water studies for the content of dioxide and chlorites, carried out at the treatment facilities by the laboratory of the Dnipro water pipeline in order to establish the features of the formation and efficiency of chlorite removal when using the applied water treatment technology. Also, selective studies of chlorine dioxide and chlorites in the water supply were carried out by titrimetric and photometric methods, the results of which coincide with the data obtained on the water supply using the ion chromatography method. Main results. A positive hygienic assessment of the modern new technology for the preparation of drinking water from surface sources using chlorine dioxide instead of chlorine gas is given. It is shown that with high purifying and disinfecting effects of water treatment with chlorine dioxide, its by-products, in particular, toxic chlorites, are constantly formed in it, the levels of which are directly dependent on the doses of chlorine dioxide used, which vary according to the seasons of the year. In general, the primary dose of chlorine dioxide and chlorites in the water after CWR, entering the water supply networks, is reduced by 89.3-92.0% for chlorine dioxide, and by 76.2-85.6% for chlorites. At the same time, the concentration of chlorine dioxide in disinfected water is always within the normal range - at least 0.1 mg / dm3, and chlorites often exceed the national hygienic standard (0.2 mg / dm3), but does not go beyond the standard recommended by WHO (0.7 mg/dm3). The highest concentrations of chlorites are formed in water in summer (on average 0.35 mg/dm3) in accordance with the increased doses of chlorine dioxide during this period (on average 2.51 mg/dm3), and the lowest in winter (on average 0.17 mg/dm3). Conclusions. As a result of the study, it was found that the process of treating natural water with chlorine dioxide is accompanied by the formation of its by-products in water, mainly toxic chlorites, the levels of which depend on the doses of chlorine dioxide used and are the lowest in winter and the highest in summer. After coagulation treatment of the source water with aluminum sulfate and ferric chloride (ratio 10:4-5), settling and filtering the level of chlorites in water (LCW) is intensively reduced, but not always reach the standard values. In summer, the maximum levels of chlorites in water with LCW can be higher than the national hygienic standard (0.2 mg/dm3) and range up to 0.7 mg/dm3, which corresponds to the WHO recommended standard for this substance in drinking water. The issue of revising the national standard for chlorites in water from 0.2 mg/dm3 to 0.7 mg/dm3 after appropriate scientific justification is being raised.

Dry-column Vacuum Chromatographic Removal of Hg2+ from Wastewater Based on an Acridino-crown Ether-modified Spherical Silica Gel Adsorbent

Dry-column vacuum chromatographic technique is introduced for remediation of wastewater for the first time. A previously prepared chemically modified silica gel containing covalently immobilized Hg2+-selective acridino-crown ether selector molecules was used as an adsorbent. Removal of Hg2+ from highly contaminated river water was carried out to study practical applicability. Adsorption capacity, preconcentration factor, pH-sensitivity and selectivity in separation were determined. The adsorbent proved to be outstanding in selectivity, only Ag+ and Cu2+ interfered among 29 cations, was inert toward organic contaminants, exhibited regenerability and pH-independency between 3.0 ≤ pH ≤ 7.0. The proposed method showed a moderate efficiency in both adsorption (32 mg Hg2+ / 1 g adsorbent) and preconcentration (preconcentration factor of 100). A maximum 10 L of wastewater / 1 g adsorbent ratio is recommended as an upper limit for applicability. The described method showed a unique robustness and simplicity compared to conventional ion-chromatographic methods and an improved selectivity over physical interaction- or simple functional group-based adsorptions.

89 Improvements to a Method for the Determination of Hexavalent Chromium in Workplace Air

Abstract ISO 16740:2005 specifies an ion chromatographic method for the determination of the time-weighted average mass concentration of hexavalent chromium in workplace air and is applicable to the determination of masses of 0,01 micrograms to 10 micrograms of hexavalent chromium per sample, without dilution. For a nominal 1 cubic metre air sample, this equates to a measurement range of between approximately 0,01 micrograms per cubic metre to 10 micrograms per cubic metre, suitable for assessing exposures in plating or weld shops. However alkaline extractants, required to liberate insoluble chromates from air samples collected in paint shops, can be contaminated with trace levels of chromium thereby negating the inherent sensitivity of this method. Work to address this issue, by sourcing and testing cleaner reagents, will be presented.

Application of Ion Chromatography for the Reliable Quantification of Ammonium in Electrochemical Ammonia Synthesis Experiments: A Practical Guide.

Assessing novel electrocatalysts for the electrochemical ammonia synthesis (EAS) requires reliable quantitative trace analysis of electrochemically produced ammonia to infer activity and selectivity. This study concerns the development of an ion chromatography (IC) method for quantitative trace analysis of ammonium in 0.1 M sulfuric acid electrolyte, which is applied to EAS gas-diffusion electrode (GDE) experiments with commercial chromium nitride as electrocatalyst. The developed IC method is highly sensitive, versatile, and reliable, achieving a limit of quantification (LOQ) of 6 μg l-1 (6 ppbmol ) ammonium. The impacts of the sample matrix, dilution, and neutralization, as well as contamination, on the quantitative analysis by IC are analyzed. Experimental constraints result in an effective LOQ including dilution of 60 μg l-1 for the determination of ammonium in 0.1 M sulfuric acid electrolyte, owing to necessary sample dilution. The practical guide presented herein is intended to be very relevant for the field of EAS as a guideline and applicable to a broad range of catalyst systems and ion chromatography devices.

Comprehensive characterization of narirutin metabolites in vitro and in vivo based on Analogous-Core recursion analysis strategy using UHPLC-Q-Exactive Orbitrap MS/MS

Narirutin, extracted from the dried ripe pericarp of Rutaceae orange and its cultivated varieties, is a dihydroflavone compound with various biological activities and pharmacological effects. So far as we know, the metabolism profiling of narirutin has been insufficient until now. In the present study, an efficient method was employed to perform rapid analysis and identification of narirutin metabolites by using ultra-high performance liquid chromatography quadrupole exactive orbitrap MS/MS (UHPLC-Q-Exactive Orbitrap MS/MS) combined with an analogous core recursion (ACR) analysis strategy. Firstly, according to the basic core structure of the dihydroflavonoid, the cleavage mode and fragmentation ions of narirutin were summarized. Secondly, based on the difference of the substituent groups, the fragment ions of narirutin were preliminarily inferred and verified by the secondary mass spectra of its standard compound. Thirdly, the fragment ions of narirutin in positive and negative ion modes were summarized to provide a basis for the identification of metabolites. Fourthly, candidate metabolites were accurately and tentatively identified according to the cleavage law of mass spectrometry, literature reports, comparison of reference substances, and especially the diagnostic fragment ion clusters (DFICs) and characteristic suggestive ions (CSIs) deduced preliminarily. Finally, a total of 46 metabolites (30 in vivo and 19 in vitro), including prototype drugs were identified based on the ACR analysis strategy, chromatographic retention behavior of metabolites, corresponding ClogP value and accurate molecular weight. Among them, 22 metabolites were discovered in rats plasma, 12 in urine, 4 in liver tissue, 19 in liver microsomes, respectively. Additionally, metabolites relative contents were also studied by extracted ion chromatography (EIC) method. Our result also illustrated that narirutin primarily underwent glucuronidation, sulfation, glutathione binding, deglycosylation, oxidation, reduction, methylation, hydroxylation, ring-opening and their composite reactions. A novel strategy was constructed to comprehensively elucidate the biotransformation pathways of narirutin in vitro and in vivo, and a systematic metabolic profile of narirutin was generated. This study provided a great reference for further understanding of the biotransformation pathways and guiding for clinical application of narirutin.

Preparation of Fluorine Certified Reference Material for Fluoroether Rubber

High-pressure free radical emulsion polymerization was used to prepare the fluorine certified reference material candidates for fluoroether rubber. Ion chromatography method and high performance liquid chromatography were adopted for the determination of the certified reference material, and various sources of uncertainty in the determination process were analyzed and calculated to gain the expanded uncertainty by synthesis. The homogeneity of the certified reference material was checked by F test and the stability was investigated by t test. The results show that the prepared fluorine certified reference material for fluoroether rubber has accurate value and good homogeneity and stability.

Improving the Method for Measuring Bromine Compounds in Flue Gas

The method detection limit (MDL) using UV-VIS spectrometry (UV/VIS) is the primary method to detect bromine compounds in the flue gas. However, the level of bromine compounds in the flue gas is 0.6 ppm, reaching 20% of the emission limit of 3.0 ppm, which limits the analysis of low-concentration samples. As per the United States Environmental Protection Agency and official test standards for water pollution, bromine compound analysis was performed using ion chromatography (IC). Hydrogen chloride was analyzed using IC, referencing official test standards for air pollution. Therefore, 0.1 M NaOH and distilled water (D.W.) were applied to the absorption solution of the IC analysis sample. Validation was conducted for IC (D.W.), IC (0.1 M NaOH), and UV/VIS (0.1 M NaOH) to improve the analysis method for bromine compounds in the flue gas. The linearity (R<sup>2</sup>) of the calibration curve for IC (D.W.) satisfied the R<sup>2</sup> (0.98 or more) value calculated in the UV/VIS of the official test standards for air pollution. However, the R<sup>2</sup> of UV/VIS (0.1 M NaOH) and IC (0.1 M NaOH) was not satisfied. In IC (D.W.) analysis results, the average values of MDL, MLQ (minimum level of quantification), accuracy and precision were 0.127 ppm, 0.403 ppm, 3.7%, and 102.9%, respectively. MDL and MLQ showed the lowest concentration compared to the other two methods, and had high accuracy and precision. Regarding the recovery rate by the absorbing liquid, IC (D.W.) was the highest at 93.55%, followed by UV/VIS (0.1 M NaOH) and IC (0.1 M NaOH). This study analyzed bromine compounds in flue gas with higher accuracy and precision using the IC (D.W.) method compared to IC (0.1 M NaOH) and UV/VIS (0.1 M NaOH).

Determination of Cations and Anions in Desulfurization Waste Water of Coal-Fired Power Plant by Ion Chromatography.

The reliable and accurate determination of corrosive anions at sub- to low-μg/L levels is a challenging analytical problem. In this manuscript, a simultaneous determination method of cations and anions in power plant water samples was established by large volume injection ion chromatography. The analytical parameters including separation column, the suppressor current and the elute concentration were optimized. Results showed good separation under the optimum conditions, and the calibration curves of all analytes were linear with good coefficient of determination (r2) >0.997, and the mean recoveries for all analytes ranged from 75.62 to 118.58% with RSD of 0.07-4.83%. The established method was successfully applied to determine the cations and anions in realwaste water samples from coal-fired power, and was verified by inductively coupled plasma optical emission spectrometry and electrometric titration. The relative deviation between methods was all below 6.72%, which indicated good accuracy of the established ion chromatography method. The results could also provide reference for the precise and rapid detection of cations and anions in environmental water samples.

Небезпечні хлорити у питній воді: утворення та видалення з використанням діоксиду хлору У технології водопідготовки

he aim of work was to study the features of the formation and removal of toxic chlorites at the treatment facilities of the Dnieper water pipeline in Kyiv, where chlorine dioxide is used in water treatment technology, and the influence of priority natural and technological factors on these processes. Materials and methods: The studies were carried out in 2021-2022. at the Dnieper waterworks in Kyiv, where chlorine dioxide is used instead of chlorine in water treatment technology. We have analyzed data from water studies for the content of dioxide and chlorites, carried out at treatment facilities by the laboratory of the Dnieper water pipeline in order to establish the features of the formation and efficiency of chlorite removal in water treatment technology. Also, selective studies of chlorine dioxide and chlorites in the water supply were carried out by titrimetric and photometric methods, the results of which coincide with the data obtained on the water supply using the ion chromatography method. Main results: A positive hygienic assessment of the modern new technology for the preparation of drinking water from surface sources using chlorine dioxide instead of chlorine gas is given. It is shown that with high purifying and disinfecting effects of water treatment with chlorine dioxide, its by-products, in particular, toxic chlorites, are constantly formed in it, the levels of which are directly dependent on the doses of chlorine dioxide used, which vary according to the seasons of the year. In general, the primary dose of chlorine dioxide and chlorites in the water after the clean water tank (CWT) entering the water supply networks is reduced by 89,3-92,0% for chlorine dioxide, and by 76,2-85,6% for chlorites. At the same time, the concentration of chlorine dioxide in disinfected drinking water is always within the normal range - not less than 0,1 mg/dm3, and chlorites - most often exceeds the national hygienic standard (0,2 mg/dm3), but does not exceed the standard recommended by the WHO ( 0,7 mg/dm3). The highest concentrations of chlorites are formed in water in summer (on average 0,35 mg/dm3) in accordance with the increased doses of chlorine dioxide during this period (on average 2,51 mg/dm3), and the lowest in winter (on average 0,17 mg/dm3). Conclusions: The studies carried out at the Dnieper water pipeline, where chlorine dioxide was introduced into the traditional water treatment technology, made it possible to establish the following. The process of treating natural water with chlorine dioxide is accompanied by the formation of its by-products in water, mainly toxic chlorites, the levels of which depend on the doses of chlorine dioxide used and are the lowest in winter and summer. After coagulation treatment of the source water with aluminum sulfate and ferric chloride (ratio 10:4-5), settling and filtration, the levels of chlorites in drinking water (CWT) decrease intensively, but do not always reach regulatory values. In the summer period, the maximum levels of chlorites in drinking water with RCHV can be higher than the national hygienic standard (0,2 mg/dm3) and range up to 0,7 mg/dm3, which corresponds to the WHO recommended standard for this substance in drinking water. The issue of revising the national standard for chlorites in water from 0,2 mg/dm3 to 0,7 mg/dm3 after appropriate scientific justification is being raised.

ANALYSIS OF METHODS FOR DETERMINATION OF CHLORINE DIOXIDE, CHLORITE AND CHLORATE ANIONS IN DRINKING WATER

The analysis shows that the primary measure for the purification of drinking water is its reliable disinfection with oxidants, which are chlorine and its compounds, chlorine dioxide, ozone. The aim of the article is to analyze the existing methods for determination of chlorine dioxide, chlorite, hypochlorite and chlorate anions in drinking water. To analyze the chlorine dioxide strength solutions (to control the generator performance) the iodometric method (determination of chlorine dioxide concentration, concentration of free chlorine, chlorite and chlorate anions; relative error ≤ 5%) and the method of direct absorption at 445 nm (determination of chlorine dioxide concentration in the range of concentrations of 100-700 mg / l; relative error ≤ 2%) were used. To analyze the residual concentrations of chlorine dioxide, chlorite and hypochlorite anions in their joint presence the titrimetric and photometric methods with N,N-діетил-1,4-фенилендіамінсульфатом (DFD) (error of determination is of 0.05 mg/l) were used as well as iodometric method with photometric determination of iodine at 350 nm in the concentration range 0.01-0.5 mg/l. To analyze the residual concentrations of chlorine dioxide (selective methods), such methods were used: the photometric method with chlorophenol red in the concentration range of 0.02-0.7 mg/l; relative error ≤ 5%; photometric method with chromic violet acid in the concentration range of 0.1-1.5 mg/l. The method of ion chromatography was used to analyze the residual concentrations of chlorite and chlorate anions. Given the necessity for harmonization of domestic regulatory and guidance documentation with European one, it should be considered as necessary to control chlorites and chlorates in drinking water by method of ion chromatography. It is appropriate to conduct research on the approbation of ion chromatography method for the simultaneous determination of chlorites and chlorates in samples of water after its disinfection by various oxidants (sodium hypochlorite, ozone, chlorine dioxide).

Analyzing Organofluorine Compounds in the Environment Using Combustion Ion Chromatography (CIC) and Other Methods

Organofluorine compounds are potential contaminants in the environment, particularly in natural water sources. Leo W. Y. Yeung, PhD, is a Senior Lecturer in the School of Science and Technology of the Man-Technology-Environment Research Centre (MTM) at Örebro University in Örebro, Sweden. His research has involved the analysis of organofluorine compounds of concern in the natural environment. We recently spoke to him about his work using combustion ion chromatography (CIC) and other methods to analyze organofluorine and specific perfluoroalkyl and polyfluoroalkyl substances (PFAS) compounds in environmental samples.

Quantitation of free cyanide using ion exchange chromatography in Neisseria meningitidis serogroups A, C, W, Y and X conjugates used in vaccine manufacture.

Polysaccharide vaccines essentially used in the prevention of bacterial infections are known to be good immunogens when conjugated to an immunogenic protein using various cyanylating agents. Analysis of residual cyanide in polysaccharide conjugate vaccines is an ardent task due to the complexity of the sample matrices and the lack of suitable methods. We report a selective ion chromatography method with electrochemical detection using IonPac AS7 column for estimation of residual cyanide in meningococcal serogroups A, C, W, Y and X bulk conjugates in presence of other interfering ions. Gold electrode and Ag/AgCl reference electrode ensures sensitivity and reproducibility of cyanide quantitation. The calibration curve of the method is linear having r2 ≥0.990 over the concentration range 1.45ng/mL to 93.10ng/mL. The recovery of cyanide in bulk conjugates ranged between 96.0% and 108.9%. The limits of detection and quantitation were 0.50ng/mL and 1.45ng/mL which corresponds to 0.31ng/μg and 0.91ng/μg of polysaccharide respectively. The method validation and feasibility study were performed using Men W and Men X bulk conjugates respectively with in house residual cyanide specification due to unavailability of pharmacopeia guidelines. The method is reproducible and can accurately quantify residual cyanide in purified meningococcal bulk conjugates.

Conditions of formation and sources of fluids of the birthplace of barren residential quartz of hydrothermal-metamorphogenic-metasomatic and hydrothermal-metamorphogenic genesis (Middle and South Urals)

The paper considers the conditions of quartz formation of hydrothermal-metamorphogenic-metasomatic and hydrothermal-metamorphogenic genesis of deposits and manifestations of the Middle and Southern Urals based on the study of fluid inclusions by methods of thermobarogeochemistry, ion and gas chromatography. It is established that the studied quartz objects are formed in a wide temperature range, against the background of insignificant differences in pressure values. It is shown that the temperatures of mineral formation in deposits of hydrothermal-metamorphogenic-metasomatic genesis vary from 440-230 ° C at a pressure of 1.2-1.4 kbar. The formation of these veins occurred with the participation of K-Mg-Fe-chloride fluid with a salinity of 1.2-8.7 wt. % NaCl-eq., depleted Mg and Fe due to the deposition of magnesia-ferruginous carbonates. A typomorphic feature of hydrothermal-metamorphogenic-metasomatic quartz is the high values of boron associated with the placement of quartz veins among pegmatoids and the presence of boron-containing mineral inclusions on quartz-vein objects. Veins of hydrothermal-metamorphogenic genesis were formed when the crack system was filled with quartz with the participation of a substantially K-Na chloride fluid (0.2-15.5 wt. % NaCl-eq.), at homogenization temperatures of 435-335 ° C and a pressure of 1.3-2.3 kbar. In the composition of fluid inclusions of hydrothermal-metamorphogenic-metasomatic quartz, the sum of "harmful" components (H2O, CO2, CH4, Cl, B, Na, K, Mg and Li) is less than in hydrothermal-metamorphogenic quartz. The studied quartz deposits and veins were formed in the range of temperatures and pressures not higher than the green shale stage during several successive stages: the formation of quartz veins – in a more high-temperature hydrothermal stage, while subsequent changes in quartz veins occurred under the influence of metamorphism processes, with a decrease in temperature. Subsequent changes are associated with the appearance of fracturing, cataclysm and recrystallization of quartz bodies with a decrease in grain size.

Suppressor and calibration standard limitations in cation chromatography of ammonium and 10 alkylamines in atmospheric samples.

Ammonia (NH3) and alkylamines are ubiquitous in the atmosphere and have been suggested to play important global roles through new particle formation and aerosol growth. In this work, we optimized an ion-chromatographic (IC) method to separate and quantify the ten most abundant atmospheric alkylamines with high selectivity and separation efficiency, using 4 μm packed columns and resin-based suppressors, alongside stabilizing amine standards. Modern resin suppressors operating on a gradient elution program affected the linear response of this IC technique. Calibration statistical analyses found a loss of analytes in these cation-exchange devices. Suppressor operational longevity was optimized by using a stepped current and an external water supply, which improved precision, accuracy, and LODs compared to other suppression modes. When this new method was applied to real samples, amines were found ubiquitously in size-resolved marine aerosol samples; monopropylamine, isomonopropylamine, and monobutylamine were detected and quantified, which have not been reported before. The molar ratio of the sum of aminium to ammonium ranged from 0.02 to 0.2, showcasing the application of the developed method towards studying the diversity and importance of alkylamines in coastal marine particle composition. The new analytical method also found NH3 present in a suite of new homes with a mean mixing ratio of 25 ± 15 ppbv; a common level reached between homes across the study during the first year of occupation which can then be transported outdoors.

Determination of tetrafluoroborate in wastewaters by ion chromatography after ion pair liquid-liquid dispersive microextraction

The ion chromatographic method was developed to determine tetrafluoroborate ion (BF4-) in different types of water using ion pair liquid-liquid dispersive microextraction. Tetrafluoroborate was extracted into an organic phase (1,2-dichloroethane) as an ion pair with a tetrabutylammonium cation (TBA+). The most complete formation of [(ТBА+)(BF4-)] was observed at ion-pair reagent concentration of at least 5 mmol L-1 (C(BF4-) ≤ 1mg L-1). Ultrasonic irradiation was used to disperse the extractant. The achieved concentration factor (K) was 29±3, and the degree of extraction (R) was 50±5%. The limit of detection of tetrafluoroborate using the microextraction technique was 7×10-3 mg L-1. The method applies to the analysis of different water origins. The presence of the main contained anions does not interfere with the microextraction and chromatographic determination of tetrafluoroborate. The maximum molar ratio of BF4- to diverse ions is 1:104 for fluoride, chloride, bromide, nitrate ions, and 1:102 for sulfate and perchlorate ions.

Development of Analytical Methods for the Determination of N-Bromosuccinimide in Different Active Pharmaceutical Ingredients by High-Performance Ion Chromatography with Suppressed Conductivity Detection

Product safety is important for medicines. For drugs on the market, it must be demonstrated that the levels of toxic contaminants are below the permitted limits. These impurities are used as reagents or are generated during synthesis. N-bromosuccinimide is used as a brominating agent in the synthesis of some active pharmaceutical ingredients. The determination of N-bromosuccinimide is difficult due to its high reactivity. In this work, a high-performance ion chromatographic method was developed for the determination of N-bromosuccinimide. The ion chromatographic measurement can be performed in two ways, one involves the assay of the resulting bromide ion and the other is via the assay of the 3-carbamoyl propanoic acid ion produced from the succinimide. Both acid ions were analyzed on an anion exchange column by gradient elution with potassium hydroxide eluent and detection was performed by a suppressed conductivity detector. During the method development, the results showed that the measurement of bromide ion was more selective than the measurement of 3-carbamoyl propanoic acid ion. Two different types of active pharmaceutical ingredients (API), i.e., prasugrel and favipiravir, were chosen to test the developed method and sample preparation. For both APIs, sample preparation was performed in a vial and consists of liquid–liquid extraction with an alkaline reagent. Finally, the anion exchange ion chromatography method was validated at the limit value level, and harmonized with the guidelines. For prasugrel, the quantification limits and the accuracy at the limit level are 7.2 ppm and 96.4%, while for favipiravir these are 7.5 ppm and 114.7%, respectively.

X-ray fluorescence analysis of sulfate-ion in aqueous solutions by dried drop technique using a portable spectrometer

In this paper authors propose the methodology of X-ray fluorescence determination of sulfate-ion in aqueous solutions with preconcentration by dried drop technique using portable energy dispersive spectrometer NITON FXL 959 GOLDD+. The represented measuring procedure has been tested in a wide range of sulfate-ion concentrations (10–4200 mg/l) during exploration the groundwater samples of the Over Jurassic Aquifer complex of the Moscow region and drainage water of the sulfide porphyry-copper mineralization of the Nakhodka ore field (Western Chukotka). Verification of the measuring procedure is based on results of the water investigation by ion chromatography and titration methods.

Use of ion chromatographic pulsed amperometric method (IC-PAD) for measuring aqueous sulfide in synthetic and real domestic wastewater

Sulfide detection in domestic wastewater is widely demanded, as sulfide induces odour nuisance and wastewater assets corrosion. However, traditional sulfide detection methods are usually plagued by the limited detection range or interference from impurities. To address these constraints, this study improved the ion chromatographic pulsed amperometric method (IC-PAD) and tested its validity for use in domestic wastewater. Prior to sulfide detection, sulfide-containing sample collection usually requires the use of sulfide antioxidant buffers (SAOB) to minimize sulfide loss. Different sample matrixes require different SAOB recipes, which increases complexity and uncertainty when measuring different environmental samples. Therefore, this study also developed a more convenient and generic sample collection method without the addition of SAOB. The results indicated that the proposed SAOB-free sample collection method could minimize the sulfide loss during sample collection. The IC-PAD method showed a wide linear detection range up to 10 mg-S/L. The detection limit was 3 μg-S/L. Matrix effect studies showed that 1 g/L glucose, formate, acetate, methanol, ethanol, propionate, butyrate, lactate, or sulfate had no evident interference on sulfide measurement. However, 5 mM phosphate buffer led to interference, but reducing the KOH eluent concentration from 62 to 30 mM avoid this interference. Wolfe's vitamin mixture and Wolfe's modified mineral mixture could cause diminutive interference equivalent to 2.53 ± 1.32 μg-S/L sulfide. Moreover, the interference caused by chloride indicated that the IC-PAD method is more applicable for measuring sulfide in low-chloride wastewater. To this end, the IC-PAD method showed high accuracy and precision in the real domestic wastewater samples with chloride concentration of 68 mg/L. The recovery was higher than 97% and the relative standard deviation (RSD) was lower than 1.2%. This study demonstrated the potential use of IC-PAD method for measuring sulfide in real domestic wastewater and possible interference from the solution matrix to be considered.