Suppressed Conductivity Detection Research Articles

Analysis of calcium ions in saliva of the before and after sugar rinse

The purpose of this study was to evaluate the salivary concentration of calcium cations and their variation before and after a sucrose and glucose rinse, and to investigate the relationship between the levels of each compound. Saliva samples were obtained from 34 subjects before and up to 60 min after intake of a 10% sucrose and glucose solution at 2-week intervals. Calcium in human saliva were determined via anion - exchange chromatography with an anion - suppressed conductivity detector using 12mM sulfuric acid. The concentrations of calcium before sucrose rinse were 39.7mg/L(9.3%), respectively. The calcium cation contents in the saliva were reconstituted after the sugar rinse and the concentrations of some ions showed that they are highly related to each other.

Remediation of Chlorinated Alkanes by Vitamin B12and Zero-Valent Iron

Chlorinated alkanes were heavily used in a wide range of industrial applications including as degreasers, paint strippers, chemical intermediates, and soil fumigants. These compounds are an environmental concern due to the adverse health effects associated with them and have been detected in environmental matrices including soils and groundwater. Chlorinated alkanes are recalcitrant, and current remediation methods that employ zero-valent iron (ZVI) are unable to directly dehalogenate these compounds, limiting the available approaches forin situremediation of these widely utilized chemicals. This study employed a novel approach for the remediation of 1,2,3-trichloropropane (TCP), 1,2-dichloropropane (1,2-DCP), 1,3-dichloropropane (1,3-DCP), 1-chloropropane (1-CP), and 1,2-dichloroethane (1,2-DCA) in the presence of ZVI and vitamin B12, a naturally occurring electron mediator. Batch reactions were performed in order to determine a kinetic model for the associated degradation mechanisms. Dechlorination byproducts were confirmed through gas chromatography-mass spectrometry (GC-MS) coupled to a purge and trap. Free chloride was quantified by ion chromatography (IC) utilizing suppressed conductivity detection. In the absence of vitamin B12, reductive dechlorination of chlorinated alkanes was observed to not occur when exposed to only reactive ZVI particles (<5 μm). However, in the presence of ZVI combined with vitamin B12, complete reductive dechlorination was observed and followed a pseudo-first-order reaction.

Ion chromatographic method for the determination of orotic acid in urine

Excess urinary orotic acid excretion occurs in patients with some inborn errors of metabolic pathways such as pyrimidine synthesis and urea cycle. Thus, rapid diagnosis of orotic aciduria has a vital importance for patients. In this paper, a novel method for determination of orotic acid in urine samples by ion chromatography with suppressed conductivity detection was investigated. The separation of orotic acid from urine matrix was accomplished by using an anion exchange column with optimized isocratic eluent program which utilized 50 mM NaOH. The other chromatographic conditions were as follows: the suppressor current was 31 mA; the flow rate of mobile phase was 0.25 mL min−1; the column temperature was 30 °C; sample loop volume was 10 μL. Under optimized conditions, the limit of detection was 0.2 μmol L‾1. Dramatically elevated orotic acid concentration was observed on pathological urine samples comparing to healthy urines, as expected. There are a good many advantages of the proposed method, but using an environmentally friendly reagent free system, no organic solvent employment and its quick nature, and being a sensitive and reliable method are the most obvious ones. The proposed method, therefore, may be utilized as an alternative technique for clinical laboratories.

Quantification of Inorganic Anions in Tea (Camellia Sinensis (L) O. Kuntze) Tissues and Soil Using Ion Chromatography Coupled with Conductivity Detector

ABSTRACTA simple ion chromatographic method is proposed for the simultaneous quantification of five inorganic anions in samples derived from tea system with a suppressed conductivity detector. For this purpose extracts of leaves, roots and soils of tea obtained at room temperature yielded chromatographic profiles with substantial differences in the relative contents of fluoride (F−), chloride (Cl−), nitrate (NO3−) and sulfate (SO4 2-). Although Cl− and SO42- were common to each extracted sample in different categories and accounted for the majority of the anions present, one additional anion peak was detected in root and leaf tissues. Irrespective of the clone and sample investigated the average F− content varied from 253 to 1664 mg kg−1, Cl− varied between 60 and 1789 mg kg−1, NO3− varied from 119 to 188 mg kg−1 and SO42- varied between 55 and 6779 mg kg−1. The anionic load was at its crest in clone UPASI – 3 in all the three categories of samples with few exceptions. Among the samples investigated, tea roots contained a considerable amount of major anions, while tea soils had the lowest amount of the detected anions. The recovery of all the quantified anions was above 95%. The correlation coefficient for all anions where above 99.50%. The concentration of nitrite (NO2−) was below the limits of detection based on the analytical technique adopted. Anion nitrate was not detected in tea root and tea leaf extracts.

Determination of trace perchlorate in water: a simplified method for the identification of potential interferences

BackgroundPerchlorate contamination of water and food poses potential health risks to humans due to the possible interference of perchlorate with the iodide uptake into the thyroid gland. Perchlorate has been found in food and drinking, surface, or swimming pool waters in many countries, including the United States, Canada, France, Germany, and Switzerland, with ion chromatography (IC) being the preferred analytical method. The standardization of a robust ion chromatographic method is therefore of the high interest for public health and safety. This article summarizes the experiments and results obtained from analyzing untreated samples, considering the sample’s electrical conductance as guidance for direct sample injection as described in EPA 314.0.ResultsThe suitability of ion chromatography with suppressed conductivity detection was tested for water samples in order to check the influence of matrix effects on the perchlorate signal of untreated samples. A sample injection volume of 750 μL was applied to the selected 2 mm IC column. The IC determination of perchlorate at low µg/L levels is challenged by the presence of high loads of matrix ions (e.g., chloride, nitrate, carbonate, and sulfate at 100 mg/L and above). Perchlorate recovery is impaired with the increasing matrix ion concentrations, and its chromatographic peak is asymmetric particularly at low perchlorate concentrations. The identification of the individual maximum concentration of interfering anions like chloride, nitrate, and sulfate that influence perchlorate recovery helps to reduce the number of sample preparation steps or an obligatory measurement of the electrical conductivity of the sample. Within the scope of this study, samples containing less than 125 mg/L of either anion did not need sample preparation.ConclusionThe identification of the maximum concentration of interfering anions like chloride, nitrate, and sulfate influencing perchlorate recovery provides a simplified alternative to the EPA 314.0 method. This approach reduces unnecessary sample preparation steps while allowing a reliable prognosis of possible interferences and maintaining result quality. This study was performed to support the development of a respective international standard, which is being established by the International Organization for Standardization (ISO). The results of the study are also intended to be used as guidance for interested laboratories to optimize the analytical workflow for trace perchlorate determination.

Simultaneous Determination of Different Anions in Milk Samples Using Ion Chromatography with Conductivity Detection

The description of a simple method for simultaneous determination of chloride, nitrate, sulfate, iodide, phosphate, thiocyanate, perchlorate, and orotic acid in milk samples was outlined. The method involves the use of dialysis cassettes for matrix elimination, followed by ion chromatography on a high capacity anion exchange column with suppressed conductivity detection. The novelty of dialysis process was that it did not need any chemical and organic solvent for elimination of macromolecules such as fat, carbohydrates and proteins from milk samples. External standard calibration curves for these analytes were linear with great correlation coefficients. The relative standard deviations of analyte concentrations were acceptable both inter-day and intra-day evaluations. Under optimized conditions, the limit of detection (Signal-to-Noise ratio = 3) for chloride, phosphate, thiocyanate, perchlorate, iodide, nitrate, sulfate, and orotate was found to be 0.012, 0.112, 0.140, 0.280, 0.312, 0.516, 0.520, and 0.840 mg L −1 , respectively. Significant results were obtained for various spiked milk samples with % recovery in the range of 93.88 - 109.75 %. The proposed method was successfully applied to milk samples collected from Istanbul markets. The advantages of the method described herein are reagent-free, simple, and reliable.

System Design and Emerging Hardware Technology for Ion Chromatography

This review provides an overview of advances in system design for ion chromatography (IC), focusing on the suppressed conductivity detection mode. In particular, advances in automated mobile-phase generation and suppressor technology based on different electrolytic concepts are addressed and novel detection approaches are discussed. Finally, advances in multi-dimensional IC and aspects of miniaturization, including capillary IC instrumentation and chip-based IC, are discussed.

Simultaneous Determination of Dithionate and Sulfate in Leaching Solution from SO2-Leaching Pyrolusite by Ion Chromatography

A sensitive method for simultaneous determination of dithionate and sulfate using ion chromatography equipped with a suppressed conductivity detector was developed. The flow rate was 1.2 mL min–1, and the mobile phase contained KOH, which was gradient-generated by an automatic generator. The detection limits were 0.63 and 0.42 mg L–1 for dithionate and sulfate, respectively. The correlation coefficients of the calibration curves were greater than 0.997. The linearity ranges were 5–200 mg L–1, and the accuracies were in the range of 99.5–111%. The proposed method was rapid, accurate, and fully validated. Finally, the method was successfully applied to the analysis of the leaching liquid and slurry by SO2-leaching pyrolusite.

High Performance Anion Chromatography of Gadolinium Chelates.

High performance anion chromatography (HPIC) method to separate ionic Gd chelates, [Formula: see text], [Formula: see text], [Formula: see text] and free matrix anions was developed. At alkaline pHs, polydentate complexing agents such as ethylene-diamine-tetraacetate, diethylene-triamine pentaacetate and trans-1,2-diamine-cyclohexane-tetraacetate tend to form stable Gd chelate anions and can be separated by anion exchange. Separations were studied in the simple isocratic chromatographic run over the wide range of pH and concentration of carbonate eluent using suppressed conductivity detection. The ion exchange and complex forming equilibria were quantitatively described and demonstrated in order to understand major factors in the control of selectivity of Gd chelates. Parameters of optimized resolution between concurrent ions were presented on a 3D resolution surface. The applicability of the developed method is represented by the simultaneous analysis of Gd chelates and organic/inorganic anions. Inductively coupled plasma atomic emission spectroscopy (ICP-AES) analysis was used for confirmation of HPIC results for Gd. Collection protocols for the heart-cutting procedure of chromatograms were applied. SPE procedures were also developed not only to extract traces of free gadolinium ions from samples, but also to remove the high level of interfering anions of the complex matrices. The limit of detection, the recoverability and the linearity of the method were also presented.

Novel Determination of Organic Acids in Diesel and Motor Oil by Ion Chromatography

ABSTRACTA robust analytical method is required for the determination of low-molecular weight organic acids, which are potential causes of refinery and internal combustion engine corrosion. The ion chromatographic method developed in this study allows the determination of acetic acid and formic acid in diesel oil mixtures with a motor oil volume fraction of up to 10%. The hydrophobic matrix is automatically removed in-line through a matrix elution step with organic solvent and nonaqueous anion-exchange analyte extraction. Acetic acid and formic acid, as the smallest and most acidic aliphatic naphthenic acids, were determined. Gradient anion-exchange chromatography on high-capacity columns in combination with suppressed conductivity detection allowed their selective and sensitive determination. Typical recovery values were from 82 to 107% for each acid in the matrices evaluated with reproducibility less than 5% for acid fortified samples.

Validation data for the determination of perchlorate in water using ion chromatography with suppressed conductivity detection.

BackgroundPerchlorate salts are relatively stable, soluble in water, and migrate into groundwater sources. Groundwater is an essential source for drinking water suppliers. Perchlorate bears health risks as it is identified to impair normal thyroid function by interfering with iodine uptake by the thyroid gland. The development of a sensitive analytical method for the determination of perchlorate is therefore of the highest interest or public health. Ion chromatography is a sensitive method suitable for perchlorate determinations. This manuscript describes the validation of an ion chromatographic method. Perchlorate is determined by ion chromatography (IC) with conductivity detection after suppression (CD) applying isocratic elution.ResultsIn this study, the suitability of IC-CD was tested for synthetic samples, selected environmental water, drinking water, and swimming pool water in order to evaluate potential matrix effects on the perchlorate signal even after sample preparation. A sample injection volume of 750 μL was applied to the selected 2-mm-IC column. In untreated samples, the perchlorate peak can be interfered by neighbouring signals from matrix ions like chloride, nitrate, carbonate, and sulphate. Depending on the concentration of the matrix ions, the perchlorate peak can show asymmetric shape in particular when the perchlorate concentration is low. Recovery is reduced with increasing matrix ion concentrations. Dedicated matrix elimination was applied to minimize such effects. A reporting limit of 1.5 μg/L perchlorate and an expanded measurement uncertainty of 13.2 % were achieved.ConclusionThe extended method validation proves the applicability of IC based on the EPA 314.0 method for the determination of trace amounts of perchlorate in water samples of different origin. The results support the development of a respective international standard pursued by ISO. The approach evidenced its working robustness and ease of use in terms of eluent preparation, chromatographic resolution, column life time and sample preparation. Due to the simplified analytical workflow of the analytical procedure the application’s integration into the collection of methods of interested laboratories should be facilitated.

Protein Nitrogen Determination by Kjeldahl Digestion and Ion Chromatography

We report development and validation of a simple, rapid, and accurate method for the quantitation of protein nitrogen, which combines Kjeldahl digestion and ion chromatography with suppressed conductivity detection and requires nanomolar amount of nitrogen in samples (≥10 μg protein). The mechanism of suppressed conductivity detection does not permit analysis of samples containing copper (present in Kjeldahl digestion solution) and aluminum (present in many vaccines as adjuvants) due to precipitation of their hydroxides within the suppressor. We overcame this problem by including 10 μM oxalic acid in Kjeldahl digests and in the eluent (30 mM methanesulfonic acid). The chromatography is performed using an IonPac CS-16 cation exchange column by isocratic elution. The method reduces the digestion time to less than 1 h and eliminates the distillation and titration steps of the Kjeldahl method, thereby reducing the analysis time significantly and improving precision and accuracy. To determine protein nitrogen in samples containing non-protein nitrogen, proteins are precipitated by a mixture of deoxycholate and trichloroacetic acid and the precipitates are analyzed after dissolving in KOH. The method is particularly useful for biological samples that are limited and can also be applied to food, environmental, and other materials.

Determination of anion impurities in barium carbonate by ion chromatography with membrane treatment

An ion chromatographic ( IC) method with membrane treatment was developed for the simultaneous determination of anions (F, SO 4 and NO 3) in barium carbonate. The cation exchange membrane was applied in providing H in hydrochloric acid to dissolve barium car⁃ bonate and to prevent anions dissolving into the solution from hydrochloric acid. After pre⁃treat⁃ ment by acid dissolution and membrane treatment, the sample was diluted for 100 times and fil⁃ trated by a 0􀆰 22 μm membrane, then analyzed by IC using 20 mmol / L KOH as the eluent. The target anions were separated by an Ion Pac AG11⁃HC (50 mm×4 mm) and an Ion Pac AS11⁃HC (250 mm × 4 mm) ion⁃exchange columns and detected by suppressed conductivity detection with 50 mA current. Under the optimized separation conditions, the calibration curves showed good linearity (R≥0􀆰 999 6) in the range of 0􀆰 01-5􀆰 00 mg / L. The limits of detection were in 第 5期 朱彬和,等:膜处理⁃离子色谱法测定碳酸钡中的杂质阴离子 the range of 1􀆰 37-9􀆰 45 μg / L with the relative standard deviations (RSDs) of 1􀆰 87% -2􀆰 19%. The recoveries of F, SO 4 and NO 3 anions were between 84􀆰 0% and 106􀆰 2% . This method can determine the three inorganic anions (F, SO 4 and NO 3 ) in barium carbonate fast and accu⁃ rately. It is suitable for the simultaneous separation and detection of trace inorganic anions in insoluble products.

Simultaneous determination of 26 organic acids and anions in fruit juice by ion chromatography with suppressed conductivity detection using gradient elution

Simultaneous determination of 26 organic acids and anions in fruit juice by ion chromatography with suppressed conductivity detection using gradient elution

Direct Separation of Molybdenum from Solid Uranium Matrices Employing Pyrohydrolysis, a Green Separation Method, and Its Determination by Ion Chromatography.

Pyrohydrolysis is a well-established separation method, and it is being used as a sample preparation method for several materials for further determination of non-metals such as halogens, boron, and sulfur. Analytes are retained in a diluted solution that is suitable for carrying out analysis by several determination techniques and minimizing the use of concentrated reagents. Pyrohydrolysis separation of metals has not been reported yet. The present study demonstrates the pyrohydrolysis separation of Mo as MoO4(2-) from uranium materials and its subsequent determination using ion chromatography coupled with suppressed conductivity detector. With use of TGA and XRD the volatilization behavior of Mo was studied. Important parameters for the pyrohydrolysis method required for the quantitative separation of Mo were evaluated. The precision of the method was better than 5% at 25 ppm of Mo. The accuracy was evaluated by analysis of a CRM (U3O8-ILCE-IV). The method was applied to determine Mo in ammonium diuranate samples, where the conventional methods suffer from the loss of Mo.

Selective Determination of Free Cyanide in Environmental Water Matrices by Ion Chromatography with Suppressed Conductivity Detection

The study was aimed at developing suitable chromatographic conditions and pretreatment methods for reliable trace analysis of cyanide in drinking water and seawater. Separation of CN− (as CNO−), F−, Cl−, , Br−, , , , and was carried on a Dionex IonPac AS20 column. Two different methods were developed for different samples. LOD and LOQ values were 7.2 µg L−1 and 24.0 µg L−1 for Method I and were 15.4 µg L−1 and 51.3 µg L−1 for Method II, respectively. Our results did not indicate the presence of cyanide in drinking water samples commercially supplied from Istanbul markets. By the addition of 250, 500, and 1000 µg L−1 to drinking water, cyanide recoveries were found 100.1%, 104.5%, and 106.9%, respectively, by employing Method I. Method II was applied to an artificial and real seawater sample obtained from the Marmara Sea, Istanbul, where a 50 µg L−1 cyanide spike gave a recovery of 100.1%. Interferences from excessive amounts of salts in seawater were removed by using strongly acidic cation-exchange resin and melamine-formaldehyde resin. The proposed pre-treatment Method (II) and chromatographic conditions provided low LOD’s for cyanide in seawater (well below acute toxicity limits), as dilution errors and matrix effects were eliminated.

Determination of Nitrite in Whole Blood by High-Performance Liquid Chromatography with Electrochemical Detection and a Case of Nitrite Poisoning.

Although nitrite is widely used in meat processing, it is a major toxicity hazard to children and is responsible for the blue-baby syndrome. A simple and effective method to determine nitrite in whole blood has been devised using ion chromatography with suppressed conductivity detection. The blood sample was deproteinized by adding acetonitrile and purified with mini-cartridges to remove hydrophobic compounds, chloride ions, and metal ions. An aliquot of the filtrate was injected onto the ion chromatography. The retention time for nitrite was 13.8 min and the detection limit of nitrite in whole blood was 0.4 μmol/L. The calibration curve was linear (r(2) = 0.9999) over the concentration working range. The blood nitrite concentration of a victim who attempted suicide by ingesting sodium nitrite powder was determined using the present method. The basal levels for nitrite in human blood was determined with 7.1 ± 0.9 μmol/L (n = 12).

Capillary ion chromatography with on-column focusing for ultra-trace analysis of methanesulfonate and inorganic anions in limited volume Antarctic ice core samples

Preservation of ionic species within Antarctic ice yields a unique proxy record of the Earth's climate history. Studies have been focused until now on two proxies: the ionic components of sea salt aerosol and methanesulfonic acid. Measurement of the all of the major ionic species in ice core samples is typically carried out by ion chromatography. Former methods, whilst providing suitable detection limits, have been based upon off-column preconcentration techniques, requiring larger sample volumes, with potential for sample contamination and/or carryover. Here, a new capillary ion chromatography based analytical method has been developed for quantitative analysis of limited volume Antarctic ice core samples. The developed analytical protocol applies capillary ion chromatography (with suppressed conductivity detection) and direct on-column sample injection and focusing, thus eliminating the requirement for off-column sample preconcentration. This limits the total sample volume needed to 300μL per analysis, allowing for triplicate sample analysis with <1mL of sample. This new approach provides a reliable and robust analytical method for the simultaneous determination of organic and inorganic anions, including fluoride, methanesulfonate, chloride, sulfate and nitrate anions. Application to composite ice-core samples is demonstrated, with coupling of the capillary ion chromatograph to high resolution mass spectrometry used to confirm the presence and purity of the observed methanesulfonate peak.

Determination of Ethylmalonic Acid in Human Urine by Ion Chromatography with Suppressed Conductivity

We present here a new method for the determination of EMA in urine by ion chromatography (IC) with suppressed conductivity detection. The separations on an anion exchange column have been accomplished with an optimized multi-step gradient eluent program (5 mM for 0-7 min, 5-50 mM from 7 to 30 min, 50 mM for 30-40 min, 50-5 mM from 40 to 45 min, 5mM for 45-50 min at flow-rate 0.2 mL/min) using NaOH as the eluent. The temperatures of both the column and suppressed conductivity detector were 40 °C. The suppressor current was 25 mA. The injection loop volume was 100 µL. Prior to injection, a clean-up procedure has been applied to urine samples for sulfate removal using BaCl 2 precipitation followed by elimination of cationic and some organic compounds using strongly acid cation-exchange resin and C18 solid phase extraction cartridge, respectively. Concentration range of EMA for linear external calibration curve was between 0.202 -30.278 µmol/L (r 2 =0.999). The limit of detection and the limit of quantitation were 61 nmol/L and 202 nmol/L based on the signal-to-noise ratio equal to 3 and 10, respectively. The average recoveries of EMA for normal urine samples were between 98.2-99.3 % with less than 1.1 % relative standard deviation (RSD), and for pathological sample were between 97.2-107.8% with less than 1.9% RSD in both intra-day and inter-day assays. The average concentrations of EMA normalized against creatinine for healthy human urine samples and a pathological sample were 1.14 (0.88-1.50) and 128.95 (128.04-129.33) µmol mmol -1 creatinine, respectively. DOI: http://dx.doi.org/10.17807/orbital.v7i2.574

Simultaneous separation and detection of anions and thiophilic cations using capillary-size anion exchange chromatography with suppressed conductivity detection.

In this fundamental study, the simultaneous separation and detection of anions and thiophilic cations in anion exchange chromatography with suppressed conductivity detection is investigated. Mercury(II) and cadmium(II) served as model analytes. Separation and detection was performed by introducing 2-mercaptoethanesulfonate, which forms complexes with both mercury and cadmium with a strong metal-sulfur bond, into the KOH eluent. Additional to the separation on the column, these complexes were able to pass the suppressor. Subsequently, they could be detected as negative peaks. A simple model for the separation mechanism was developed based on these results. Furthermore, the effect of the eluent concentration on the retention factors of both cation complexes and standard anions was examined and quantified. It revealed that the concentration of 2-mercaptoethanesulfonate has more influence on the cations than the KOH concentration. Also, 2.0 mM of 2-mercaptoethanesulfonate had about the same effect on the anion separation as 60 mM KOH. Finally, selectivity and detection limits were investigated. The detection limits were 4.9 μM for mercury and 2.2 μM for cadmium.