Ion Chromatographic Method Research Articles

Direct ion chromatographic method for speciation micro analysis of arsenic forms in industrial samples with “rich” matrix composition

The speciation analysis of arsenic has consistently been a subject of great interest. However, it remains challenging to analyze complex matrix samples that contain both arsenic and interfering components. In this case, it can be hard to choose the right combinations of different instrumental methods, or a separation method followed by detection, which is usually done using a spectral approach (hybrid methods). In the production control of copper electrorefining, the determination of the concentration of As (III) and As (V) helps to improve the quality of the cathode copper produced. This work investigated the possibility of directly determining both arsenic forms and total As in an electrolyte bath using ion chromatography (IC) with conductometric detection. The use of the ion chromatographic approach for the determination of As(V) in complex matrix samples such as copper electrolyte must take into account the presence of potential interferences from anions such as sulphates, sulfites, selenites, selenates, etc. The results revealed that the method is accurate and precise, with As(V) quantification limits of 15 µg.L-1 and detection limits of 5 µg.L-1. This method is suitable for assessing various types of arsenic in the production of electrolytic copper, with the aim of replacing the current technique that requires liquid-liquid extraction and ICP-OES detection. This led to the following improvements: Enhanced efficiency: The method eliminates the need for extensive and time-consuming sample preparation for the initial separation of arsenic forms. At the same time, the method's characteristics are comparable to those of ICP-OES with liquid-liquid extraction, which is often used in the speciation analysis of arsenic. The method is environmentally friendly as it avoids the use of organic and poisonous extractants. The method can simultaneously analyze other anions (PO43-, SO42-, F-, Cl-, etc.) with arsenates with appropriate calibration.

ИОННОХРОМАТОГРАФИЧЕСКОЕ ИССЛЕДОВАНИЕ ОГНЕЗАЩИТНЫХ ВСПУЧИВАЮЩИХСЯ ПОКРЫТИЙ В ЭКСПЕРТИЗЕ ПОЖАРОВ

Fire protection of structures, as well as increasing the fire resistance of metal structures is an important task in reducing losses from fires. One common way to improve the fire resistance of a structure is to apply an intumescent flame retardant coating to the structure. Currently, expert practice has more often raised questions about establishing the presence or absence of fire protection on structures. The article considers the possibility of using the method of ion chromatography in order to determine the presence of fire-retardant components in the coating and determine the composition of the fire-retardant coating. The study was conducted on three flame retardant intumescent coatings with different binders. Two sample preparation methods were selected for the study: the study of directly aqueous solutions of intumescent coatings and the study of aqueous solutions of gases released during thermal destruction of coatings. Chromatograms of aqueous solutions of the tested coatings are given, indicating the presence of ions of fire-retardant components formed during hydrolysis. The results of the study showed that both methods have both advantages and disadvantages and can be used in preparation for analysis by ion chromatography to study flame retardant intumescent coatings.

Comparing the Two Methods of Ion Chromatography and Titration in Evaluating the Concentration of Sulfuric Acid Mist and Vapor in the General Air of the Electrolysis Unit of the Copper Production Industry

Comparing the Two Methods of Ion Chromatography and Titration in Evaluating the Concentration of Sulfuric Acid Mist and Vapor in the General Air of the Electrolysis Unit of the Copper Production Industry

Analytical methods for quantitating sulfate in plasma and serum.

Circulating sulfate needs to be maintained at sufficiently high levels for healthy growth and development. Animal studies have shown the adverse physiological consequences of low circulating sulfate level on the skeletal, neurological and reproductive systems. However, sulfate is not routinely measured in clinical investigations, despite the importance of sulfate being documented over the past several decades. Several methods have been developed for measuring serum and plasma sulfate level in animals and humans, including a range of barium sulfate precipitation techniques that have been a major focus of sulfate analytics since the 1960s. Evaluation of an ion chromatography method demonstrated its utility for investigation of sulfate levels in human health. More recently, liquid chromatography-tandem mass spectrometry has been used to show hyposulfatemia in a human case of mild skeletal dysplasia. This article provides an overview of analytical methods for measuring sulfate in serum and plasma, highlighting the strengths and limitations of each method.

Determination of organic fluorinated compounds content in complex samples through combustion ion chromatography methods: a way to define a “Total Per- and Polyfluoroalkyl Substances (PFAS)” parameter?

Emerging contaminants are a growing concern for scientists and public authorities. The group of per-polyfluoroalkyl substances (PFAS), known as ‘forever chemicals', in complex environmental liquid and solid matrices was analysed in this study. The development of global analytical methods based on combustion ion chromatography (CIC) is expected to provide accurate picture of the overall PFAS contamination level via the determination of extractable organic fluorine (EOF) and adsorbable organic fluorine (AOF). The obtained results may be put into perspective with other methods such as targeted analyses (LC-MS/MS). The impact of pH, the presence of dissolved organic carbon and suspended particles on AOF measurements were explored. The effectiveness of the washing step to remove adsorbed inorganic fluorine (IF) has been proven for samples containing up to 8 mgF.L−1. CIC-based methods showed good repeatability and reproducibility for the complex matrices studied. Environmental applications of these methods have been tested. AOF and EOF analyses could explain between 1 % and 23 % and 0.1 % to 2 % of total organic fluorine (TOF), respectively. The sum of PFAS compounds expressed as fluorine could explain from 0.2 % to 11 % and from 0.003 % to 5 % for AOF and EOF, respectively. These results also suggest that some fluorinated compounds are not adsorbed or extractable and/or lost by volatilisation during the application of AOF and EOF analytical procedure. These findings highlight that AOF and EOF are not entirely efficient as proxy to assess “total PFAS” for assessing environmental contamination by PFAS. However, these methods could still be applied to gain a better understanding of the sources and fate of PFAS in the environment.

Modified turbidometric microassay for the measurement of sulfate in plasma and urine

Sulfate is the fourth most abundant anion in circulation. Despite being an essential nutrient for healthy growth and development, sulfate is not routinely measured in clinical settings. In research settings, animal studies have shown that hyposulfatemia and hypersulfaturia are associated with adverse developmental outcomes. Those findings have increased interest in measuring plasma and urine sulfate levels. In this study, we describe a modified assay to measure sulfate in low volumes of plasma and urine.•A streamlined microassay to measure sulfate levels using a microtiter plate format was developed.•To determine the robustness of the assay, this method assessed reagent stability and concentrations, as well as absorbance at different wavelengths and following a range of incubation times.•The optimized microassay was used to measure sulfate level in pig plasma and urine samples, which were compared to a validated ion chromatography method.

Simultaneous determination of eight organic amines in desulfurization solution by ion chromatography

The applications of organic-amine desulfurization have steadily increased owing to its high efficiency, low cost, and low energy consumption. Different proportions of organic amines exert different effects on sulfur dioxide removal. Therefore, the accurate determination of different organic amines in the desulfurization solution is of great importance. The ion-chromatographic method for the detection of organic amines does not require a derivatization step, has simple pretreatment procedures, and allows for the simultaneous determination of many types of organic amines. In this study, a method based on ion chromatography was developed for the simultaneous determination of ethanolamine (MEA), diethylethanolamine (DEEA), n-methyldiethanolamine (MDEA), 2-amino-2-methyl-1-propanol (AMP), hydroxyethylethylenediamine (AEEA), piperazine (PZ), n-hydroxyethylpiperazine (HEPZ), and diethylenetriamine (DETA). The separation efficiency of the eight organic amines in different types of columns, leaching solutions, and column temperatures were compared. The determination was performed using an IonPac CS17 column with column temperature of 35 ℃ and gradient leaching with methyl sulfonic acid (MSA) solution via the inhibition conductance method. Samples of the desulfurization solution were analyzed using ultrapure water filtered through a 0.22 μm nylon microporous filter membrane and an OnGuard Ⅱ RP column; thus, the pretreatment steps are simple. The eight organic amines showed a good linear relationship within a certain concentration range, and the coefficient of determinations (R2) were greater than 0.998. The limits of detection (LODs) and quantification (LOQs) were determined from the mass concentrations of the organic amines corresponding to signal-to-noise ratios (S/N) of 3 and 10, respectively. LODs of 0.02-0.08 mg/L and LOQs of 0.07-0.27 mg/L were determined from a 1.0 μL sample injection. The actual recoveries ranged from 93.0% to 111%, and the relative standard deviations (RSDs, n=5) ranged from 0.31% to 1.2%. The results indicated that the proposed method has good accuracy and precision; thus, it is suitable for the determination of various organic amines in desulfurization solution.

Simultaneous detection of lower aliphatic amines and conventional cations in atmospheric PM2.5 particulates by ion chromatography

Many amine pollutants exist in the atmosphere. Lower aliphatic amines promote the formation and growth of particles into PM2.5, which damages the heart, lungs, and kidneys of the human body. PM2.5, a common atmospheric particulate pollutant with complex compositions, is the main cause of haze weather. Therefore, measuring the contents of lower aliphatic amines and cations in PM2.5 is of great significance for monitoring environmental air quality and protecting human health. This study established a suppressed ion-chromatographic method with conductivity for the simultaneous detection of four lower aliphatic amines (methylamine, dimethylamine, trimethylamine, and ethylamine) and five cations (Na+, N[Formula: see text], and Ca2+ showed high concentrations. The contents of the four lower aliphatic amines were low; however, the ethylamine content in some samples was high. The results indicate that the proposed method meets the quantification requirements for cations and lower aliphatic amines in PM2.5, with simple processing, high sensitivity, and good accuracy. It can quickly and accurately detect a large number of samples and be used to assess the pollution of small particles in the air as well as trace pollution sources to protect human health.

Suppressed Ion Chromatographic Analysis of Anionic Macroelements in Nutmeg (Myristica fragrans) Diversity Specific to North Maluku

This study proposed an ion chromatography method for analyzing anionic macroelements (fluoride, chloride, nitrite, bromide, nitrate, sulfate, and phosphate), and applied it to nutmeg (<em>Myristica fragrans<em>)</em></em> diversity to explore the potential of nutmeg as an electrolyte. The analysis method was based on a suppressed conductivity system that simultaneously analyzed the anionic macroelements on Metrohm Supp A 250/4.0 column using 8.0 mM sodium carbonate (Na<sub>2</sub>CO<sub>3</sub>) and 0.25 mM sodium bicarbonate (NaHCO<sub>3</sub>) as a mixture eluent. Excellent peak resolution and completed separation were achieved within 18 min when the flow rate of the detector was 0.8 mL/min. The peak height with calibration curves at 2.5 ‒ 30.0 mg/L concentration ranges was obtained for all anionic macroelements. All collected nutmeg samples were specific to North Maluku. Based on the standard samples used, the analysis results revealed that only four anionic macroelements (chloride, nitrate, sulfate, and phosphate) were found in the nutmeg samples, and the concentration of each anion (e.g., chloride ion, and so) was different for each type of nutmeg. The highest total of anionic macroelements concentration was found in the <em>Myristica succedanea</em> (1605.05 mg/kg) nutmeg sample,<em> </em>while <em>Myristica specioga</em> had the lowest (661.76 mg/kg). The method was validated regarding the detection limit (LOD) and reproducibility.

Chloride leaching of eucalyptus wood particles by water for pellets production

The impacts of climate change caused by the consumption of fossil fuels have encouraged the reduction of greenhouse gas emissions. The use of forest biomass for the pellets production is an alternative for energy generation. However, the high chloride content present in this forest biomass has caused human health and economic problems, which are factors that restrict the export of pellets. The main objective of this work was to reduce the chloride content in eucalyptus wood intended to produce pellets, by leaching the particles with water. Different parts of the eucalyptus tree (bark, branches, leaves, heartwood and sapwood) were characterized, and the biomass stock was determined. The chloride content determination was carried out using the selective chloride electrode and ion chromatography methods. Leaching was performed using a water/wood ratio of 25, 50, 75 or 100 L kg−1. The higher heating value (HHV) of the bark (18.47 MJ/kg), branches (20.01 MJ/kg) and leaves (22.04 MJ/kg) met the requirements of ISO 17225–2. However, their ash (1.91–4.32 %) and chloride content (0.120–0.627 %) were above what is allowed by the standard. The sapwood showed a higher content of volatile matter, ash and holocellulose, while higher values of HHV, fixed carbon, lignin and extractives content were observed for the heartwood. The chloride content present in heartwood was lower than that of sapwood and did not meet the requirements for ISO 17225–2 (≤0.03 % for B and ≤ 0.02 % for A pellets). In general, particle leaching did not significantly affect the energetic properties of wood. Leaching the particles with the lowest water/wood ratio (25 L/kg) was sufficient to remove chloride ions and meet the requirements of ISO 17225–2.

Analysis of Calcium and Phosphate Ion Extraction From Dental Enamel by Bleaching Gels Using Ion Chromatography, Micro-CT, and SEM.

To evaluate the volume and depth of enamel loss promoted by 37.5% and 7.5% hydrogen peroxide (HP) gels, and quantify the loss of calcium (Ca) and phosphate (P) ions by using ion chromatography (IC) analysis after bleaching. Sixty bovine enamel specimens were randomly divided into three groups: Control - no bleaching gel; HP37.5%, application of HP 37.5% for 45 minutes for 14 days; and HP7.5%, application of HP 7.5% for 3 applications of 8 minutes. The surface analysis (n=5) was performed using a scanning electron microscope (SEM) and dispersive energy system (EDS) to calcium and phosphorus dosage. The micro-CT was used for the enamel loss analysis (n=5). IC was used to analyze extracted Ca and P (n=10). Data were analyzed by one-way ANOVA and two-way repeated measures ANOVA, followed by Tukey and Dunnett's tests (α=0.05). Significantly higher volume and depth of enamel loss were found for bleached groups compared with the control group. HP7.5% had significantly higher enamel change than HP37.5%. SEM showed higher enamel porosity for HP37.5% and HP7.5% compared to control. The IC demonstrated a significant increase of Ca incorporated into the gel, however, only HP7.5% had a higher P presence than the control group. The HP7.5% showed higher Ca and P ion exchange than HP37.5% (p<0.001). HP37.5% and HP7.5%, caused enamel mineral changes compared with the control group. The IC method was demonstrated to be an effective methodology for detecting enamel mineral loss by the bleaching gel.

Dynamic accelerated stress test and coupled on-line analysis program to elucidate aging processes in proton exchange membrane fuel cells

The application of hydrogen proton exchange membrane fuel cells (PEMFC) in greenhouse gas emission free heavy-duty vehicles requires extremely durable PEMFC components with service lives in the range of 30,000 h. Hence suitable test and analysis methods are required that reflect realistic operation scenarios, but significantly accelerate aging. For this purpose, a dynamic accelerated stress test was developed, which is coupled with a comprehensive in-depth in-situ and ex-situ analysis program to determine the aging processes of a PEMFC membrane electrode assembly (MEA). The test comprehends dynamic cycling between low, moderate and high load, different temperature and humidity conditions as well as recovery sequences to distinguish between reversible and irreversible failure modes. All phases of the PEMFC system (i.e. solid, liquid and gaseous) are monitored on-line during aging by sophisticated electrochemical, mass spectrometric and ion chromatographic analytical methods. The structural and elemental composition of the MEA before and after the aging program (post-mortem) are investigated by X-ray fluorescence, scanning and transmission electron microscopy. This program was able to age a commercial PEMFC to end-of-life in 1000 h, while providing an accurate picture of the aging processes involved.

Ion chromatographic quantification of nine cationic components in pre-blast and post-blast residues of pyrotechnic samples

AbstractAn ion chromatographic method and its application have been described to quantify nine cationic components (lithium, sodium, ammonium, methylammonium, potassium, magnesium, calcium, strontium, and barium) in pyrotechnics (firecracker and firework) samples. The samples in this study were purchased from local shops in Ternate City, North Maluku. The method performed a mixed eluent with 4 mM HNO3 and 0.015 mM Na2EDTA, combined with a Metrosep C4-150/4.0 separation column for all quantifications. Excellent chromatograms were achieved, and the nine cationic components were eluted in less than 18 min. The calibration graphs of the quantifications were linear in the range of 1.25–37.5 mg L−1. The detection limit (LOD) at S/N = 3 was below 0.098 ppm (mg L−1). This method was applied to the pre-blast and post-blast residues of pyrotechnics samples, and the simultaneous quantification of the nine cationic components in these samples was achieved with satisfactory results.

Radiochemical isolation of 45Ti using ion chromatography

45Ti exhibits favorable decay properties for positron emission tomography (PET) imaging and can be easily produced by the bombardment of natural scandium (Sc) by protons using the 45Sc(p,n)45Ti nuclear reaction. However, separation of 45Ti from irradiated Sc targets is arduous due to the hydrolytic instability of Ti(IV) complexes, making it a significant bottleneck for routine application of this radionuclide. In the present work, we describe the development and optimization of an ion chromatographic separation method based on trapping of 45Ti on a hydroxamate-functionalized chelating resin and subsequent elution with oxalic acid at pH = 2.8. Under optimized conditions, this method enabled 45Ti-recovery of 61 ± 8% within 7 min. Sc contamination in scaled-up experiments was found to be only 3.0 ± 1.8 µg/mL. The resulting 45Ti-solution was directly used for complexation with CDTA as a model chelator, affording the corresponding [45Ti]Ti(cdta) complex with a radiochemical conversion of 73 ± 3%. Conclusively, this promising method could be transferred to automated synthesis modules and should enable the preparation of 45Ti-labeled compounds for PET imaging.

Simultaneous Assessment of the Nitrates and Nitrites in the Ground Water Samples using Optical Spectrophotometry and Validating the Appropriate Wavelength of Measurement

Background: Nitrate is a renowned pollutant in water and soil. Nitrate is used mostly as a nitrogen fertilizer. When nitrate seeps into the ground it can get into drinking water. Traces of nitrite and nitrate in drinking water may lead to methemoglobinemia in infants and with long term exposure is a possible cancer risk. Concentration of nitrate above 45 mg/L as nitrate and 10 mg/L as nitrate-nitrogen is unsuitable for domestic use according to BIS (Bureau of Indian Standards). Methods: Nitrates are mainly determined by the spectrometric, colorimetric and ion chromatography methods. Majority of these methods are slow measurement, laborious and require the use of toxic and expensive reagents. In this study, ultraviolet spectrophotometric method is utilized for detection of nitrate optically with no chemical reagents. This method is simple and cost-effective. Nitrate and nitrite concentrations were analysed at various wavelengths (220 to 370 nm) and 240 nm was found to be efficient for detecting both nitrate and nitrite. Result: Various groundwater samples in and around Karunya Campus and nearby residential places, Coimbatore, Tamil Nadu were analysed and compared with one borewell water sample from West Bengal State which was prone to contaminated ground water. The results show that all the ground water samples have nitrate and nitrite concentration within the permissible limit but the sample from West Bengal has higher concentration compared to Coimbatore samples.

Multifunctional-separation-mode ion chromatography method for determining major metabolites during multiple parallel fermentation of rice wine.

Facile and effective analysis methods are desirable for elucidating the behaviours of metabolites during fermentation reactions. Herein, a multifunctional-separation-mode ion chromatography (MFS-IC) method was developed for the simultaneous monitoring of major metabolites during multiple parallel fermentation, including those related to central carbon metabolism (saccharification, glycolysis, alcoholic fermentation, and the tricarboxylic acid (TCA) cycle). The use of two types of sulfo-modified size-exclusion columns and phthalic acid as the eluent allowed the separation of oligosaccharides (disaccharides, trisaccharides, and tetrasaccharides), glucose, pyruvate, and major organic acids during the TCA cycle (cis-aconitate, citrate, iso-citrate, malate, fumarate, and succinate but not α-ketoglutarate) from other non-target analytes. The MFS-IC method was successfully applied to monitoring the major metabolites in the rice wine brewing process. This approach can contribute to an improved understanding of metabolite behaviour during fermentation without requiring the use of expensive advanced instrumentation methods such as liquid chromatography-mass spectrometry and gas chromatography-mass spectrometry.

A method for the quantitative analysis of polar anionic pesticides in milk/infant formula, cereals and fruit and vegetables using ion chromatography coupled to tandem mass spectrometry.

Polar pesticides such as anionic or ionisable compounds have always provided a challenge for analytical chemists. Methods of analysis have been developed using a range of techniques including normal phase chromatography, ion-pairing, derivatisation and HILIC or multi-mode chromatography. These work well with some of these compounds but, except for HILIC, all of them have their limitations and none of them cover the range required by legislation. Some of these compounds, glyphosate, chlorate and phosphonic acid, are found regularly in a range of food matrices, and therefore reliable methods of analysis are essential. This study describes an ion chromatography method with tandem mass spectrometry detection which not only covers the full range of compounds required by legislation but also can be expanded to include other anionic or ionisable pesticides and metabolites. These include glyphosate and its metabolites, glufosinate and its metabolites, ethephon and its metabolites as well as fosetyl aluminium, chlorate and perchlorate. The method is fully validated according to the performance criteria from the SANTE guidelines for the analysis of pesticides in food and feed over a wide range of matrices, including milk, infant formula, cereals and fruits and vegetables. Over 300 food samples have analysed as part of our routine monitoring program.

Universal ion chromatography method for anions in active pharmaceutical ingredients enabled by computer-assisted separation modeling

Ion Chromatography (IC) is one of the most widely used methods for analyzing ionic species in pharmaceutical samples. A universal IC method that can separate a wide range of different analytes is highly desired as it can save a lot of time for method development and validation processes. Herein we report the development of a universal method for anions in active pharmaceutical ingredients (APIs) using computer-assisted chromatography modeling tools. We have screened three different IC columns (Dionex IonPac AS28-Fast 4 µm, AS19 4 µm and AS11-HC 4 µm) to determine the best suitable column for universal IC method development. A universal IC method was then developed using an AS11-HC 4 µm column to separate 31 most common anionic substances in 36 mins. This method was optimized using LC Simulator and a model which precisely predicts the retention behavior of 31 anions was established. This model demonstrated an excellent match between predicted and experimental analyte retention time (R2 =0.999). To validate this universal IC method, we have studied the stability of sulfite and sulfide analytes in ambient conditions. The method was then validated for a subset of 29 anions using water and organic solvent/water binary solvents as diluents for commercial APIs. This universal IC method provides an efficient and simple way to separate and analyze common anions in APIs. In addition, the method development process combined with LC simulator modeling can be effectively used as a starting point during method development for other ions beyond those investigated in this study.

Simultaneous separation and determination of Ti and Fe in uranium alloy by ion chromatography

A simple and reliable ion chromatographic (IC) method for the simultaneous separation and quantification of Ti and Fe in U-Ti alloys is proposed. The developed method does not require pre-separation of matrix uranium and hence direct injection of the dissolved sample into IC is feasible. Separation was realized on a reversed phase column dynamically modified with ion interaction reagent (IIR). Suitability of three IIRs was evaluated and Camphor-10-sulphonic acid (CSA) was selected. Separation of Ti and Fe was achieved by mandelic acid whereas the strongly retained U(VI) was eluted with tartaric acid. The developed method was calibrated for Ti and Fe in presence of U(VI). The limit of detection (LOD) for Ti and Fe is 0.2 µg/mL and 0.02 µg/mL, respectively. The precision of measurements was better than 5 % (RSD) at 1 ppm of Ti and 0.2 ppm of Fe. The real samples were analysed with the developed method.

Desalination of Hamipterus tianshanensis fossil by electrokinetic method: evaluation for treatment of clay-rich sandstone

The fossils of Hamipterus tianshanensis (Wang et al. in Curr Biol 24:1323–1330, 2014) and their eggs have important scientific significance because they can provide unique information about the reproduction, development, and evolution of pterosaurs. The fossils and the rock surrounding them have, however, been weathered, which including powdering and flaking, since they were relocated from Xinjiang to Beijing. The high content of soluble salts is a significant factor in fossil deterioration because the dissolution–recrystallization process can generate tremendous pressure and lead to decreased mechanical strength. This study evaluated the electrokinetic desalination performance for the fossils, and two types of poultices employed including paper pulp from Bioline® and CKS121 (cellulose: kaolin: sand = 1:2:1, w/w). Mercury intrusion porosimetry (MIP), scanning electron microscopy (SEM), ion chromatography (IC), and other methods were applied to evaluate the desalination effect. The surface salt content reduction by applied direct current (DC) was about 70%, and the inner salt content reduction was about 80%. The experimental results suggest that the electrokinetic method is a promising way to desalinate fossils. Nonetheless, cracks appeared in the surrounding rock crack after electrokinetic desalination, which can be explained by the montmorillonite swelling-induced stresses. Pre-consolidation, especially for electro-chemical method may solve the cracking problem for the clay-rich sandstone desalination.