[Advances in the application of ion chromatography-mass spectrometry in the fields of life and health].

Ion chromatography is a technique commonly used to separate strongly polar and ionizable substances; it can be used to separate, identify, and quantify ionizable compounds in complex samples when coupled with mass spectrometry, and is currently being used in the application of food analysis, drug analysis, metabolomics and clinical poisoning analysis. Herein, we review the development of ion chromatography-mass spectrometry (IC-MS), its progress over the past 20 years, and future trends in the abovementioned areas. The IC-MS research progress and applications for the determination of inorganic anions, organic acids, polar pesticides, biogenic amines, and sugars in the food field are discussed. Drug analysis applications are discussed mainly in relation to the analysis of drug impurities, identifying drug degradation products, and determination of plasma concentration, while the separation and analysis of strongly polar metabolites, such as organic acids, sugar phosphates, and nucleotides in biological matrices are discussed in relation to metabolomics. Advances in the analysis of strongly polar or ionizable toxic compounds, such as alkyl methylphosphonic acid, methylphosphonic acid, glyphosate, 3-nitropropionic acid, and indandione rodenticides, are mainly discussed in clinical poisoning analysis field. This paper is expected to become a useful reference for the further expansion and application of IC-MS in the life and health fields.

Highly sensitive two-dimensional ion chromatography mass spectrometry method for nitrite determination in hydroxypropyl methylcellulose.

Due to their potential adverse health effects, some N-nitrosamines in drug products are strictly regulated with very low maximum daily intake limits. Nitrosamines can be formed from the reaction of nitrite and secondary or tertiary amines when both species co-exist in the drug synthesis or formulation process. One key strategy to mitigate nitrosamine risk in drugs is to select low-nitrite containing pharma excipients for formulation. It is necessary to develop a sensitive method for trace nitrite determination in pharma excipients as it enables drug producers to study nitrosamine formation kinetics and select excipient suppliers. This study details the development and validation of a two-dimensional ion chromatography mass spectrometry (2D-IC/MS) method for trace nitrite determination in hydroxypropyl methylcellulose (HPMC), one of the most important pharmaceutical excipients used in many drug formulations. The 2D-IC system was operated in heart-cutting mode with a concentrator column coupling the two dimensions. A standard bore anion-exchange column was used in the first dimension (1D) to enable a large volume injection for increased sensitivity and provide improved resolution between nitrite and the interfering chloride peak. A high efficiency microbore anion-exchange column with different selectivity was used in the second dimension (2D) to resolve nitrite from other interfering species. The use of 2D-IC resulted in significantly improved resolution, solving the sensitivity loss issue due to ion suppression from an otherwise 1D separation. MS detection with selective ion monitoring and isotope labeled nitrite internal standard further improve the method specificity, accuracy, and ruggedness, as compared with conductivity detection. For trace determination, it is also extremely important to have a clean blank. For this purpose, a novel cleaning procedure using a strong anion wash was developed to remove nitrite contamination from labware. The optimized method was validated with linearity of nitrite in the concentration range of 18.5-5005.8 ng/g having a regression coefficient of >0.9999, precision with RSD at 3.5-10.1 % and recovery of 90.5-102.4 %. The limit of detection and limit of quantitation were 8.9 and 29.6 ng/g relative to the HPMC sample, or equivalent to 89 and 296 pg/g in the sample solution, respectively.

Analysis of highly polar anionic pesticides in food of plant and animal origin by ion chromatography and tandem mass spectrometry with emphasis on addressing adverse effects caused by matrix co-extractives.

Residues of various highly polar pesticides and their metabolites are commonly found in numerous food products. Some of these compounds, such as glyphosate, are not only used in large amounts in agriculture, but are also controversially discussed in public. Here, we present a method, employing ion chromatography (IC) coupled to tandem mass spectrometry (IC-MS/MS), for the analyses of glyphosate, aminomethyl phosphonic acid (AMPA), N-acetyl-glyphosate (NAGly), fosetyl, and 10 further highly polar pesticides and metabolites in various plant and animal matrices following a minimal sample preparation by means of the QuPPe method. Thorough investigations showed that an AS19 column enabled the analysis of all 14 compounds within 30 min. The best sensitivity could be obtained with the make-up solvent acetonitrile being admixed to the mobile phase at a 1:2 flow rate ratio. Matrix effects were thoroughly studied in terms of ion suppression and retention time shifts. Conductivity detection was used to monitor elution profiles of matrix co-extractives in comparison with matrix effect profiles obtained by continuous post-column infusion of a mix with 13 highly polar pesticides and metabolites. These tests indicated that a fivefold dilution of QuPPe extracts was suitable for the routine analysis of samples for MRL-conformity, as it considerably reduced matrix effects maintaining sufficient sensitivity and high recovery rates in eight different commodities. The suitability of the final method for its application in routine analysis was verified by the analysis of >130 samples containing incurred residues where the results were compared with two existing LC-MS/MS methods.

New analytical methods focusing on polar metabolite analysis in mass spectrometry and NMR-based metabolomics.

Following in the footsteps of genomics and proteomics, metabolomics has revolutionised the way we investigate and understand biological systems. Rapid development in the last 25 years has been driven largely by technical innovations in mass spectrometry and nuclear magnetic resonance spectroscopy. However, despite the modest size of metabolomes relative to proteomes and genomes, methodological capabilities for robust, comprehensive metabolite analysis remain a major challenge. Therefore, development of new methods and techniques remains vital for progress in the field. Here, we review developments in LC-MS, GC-MS and NMR methods in the last few years that have enhanced quantitative and comprehensive metabolome coverage, highlighting the techniques involved, their technical capabilities, relative performance, and potential impact.

Characterization of halogen species in seaweeds from the Antarctic using a multi-technique approach.

BACKGROUND: Despite the recognized importance, the determination of halogens in Antarctic seaweeds remains understudied. Limited research exists due to challenges associated with sample preparation, and reliable analytical techniques for this type of analysis. Therefore, further investigations are necessary to bridge this knowledge gap and gain a comprehensive understanding of halogen metabolism in Antarctic seaweeds. METHODS: In this study, seaweeds from the coast of the Antarctic continent were characterized concerning the total content of halogens and their species. For this purpose, different sample preparation methods, based on extraction and combustion, combining highly selective and sensitive chromatographic and spectrometric multi-technique approaches were used. RESULTS: By using optimized methods, it was possible to determine total halogens content, the distribution of bromine and iodine in different classes of species (lipids, water-soluble, proteins, carbohydrates, and residue), as well as the identification of iodinated amino acids (MIT and DIT) in ten brown and red seaweeds. Bromate and iodate were not detected in the samples, which presented only bromide and iodide species in their composition. Additionally, unknown bromine and iodine species were observed in different extracts evaluated. Furthermore, 25 halogenated polyphenols were identified in seaweeds, of which only four were already reported in the literature. CONCLUSION: The results obtained in this study comprise unprecedented data in the literature on species of halogens present in seaweeds from the Antarctic environment.

Simultaneous analysis of degradation products of Novichok agents and conventional nerve agents in human urine by ion chromatography-tandem mass spectrometry using ammonium regeneration solution.

An ion chromatography (IC)-tandem mass spectrometry (MS/MS) method to analyze nerve agent degradation products in human urine was developed. Six degradation products of conventional nerve agents and six Novichok agent degradation products were analyzed simultaneously despite their differences in hydrophilicity and acidity. Using ammonium regeneration solution improved the peak shapes greatly compared with the results obtained with the ordinary IC-MS/MS configuration. For urine samples, a simple pretreatment method of dilution with water and ultrafiltration was used. The detection limits of the nerve agent degradation products were sufficiently low (10-250 ng/mL) and the calibration curves showed acceptable linearity. Due to the absence of a derivatization step, throughput was higher than for our previous derivatization-liquid chromatography-MS/MS method.

Analysis of environmental pollutants using ion chromatography coupled with mass spectrometry: A review.

The rise of emerging pollutants in the current environment and requirements of trace analysis in complex substrates pose challenges to modern analytical techniques. Ion chromatography coupled with mass spectrometry (IC-MS) is the preferred tool for analyzing emerging pollutants due to its excellent separation ability for polar and ionic compounds with small molecular weight and high detection sensitivity and selectivity. This paper reviews the progress of sample preparation and ion-exchange IC-MS methods in the analysis of several major categories of environmental polar and ionic pollutants including perchlorate, inorganic and organic phosphorus compounds, metalloids and heavy metals, polar pesticides, and disinfection by-products in past two decades. The comparison of various methods to reduce the influence of matrix effect and improve the accuracy and sensitivity of analysis are emphasized throughout the process from sample preparation to instrumental analysis. Furthermore, the human health risks of these pollutants in the environment with natural concentration levels in different environmental medias are also briefly discussed to raise public attention. Finally, the future challenges of IC-MS for analysis of environmental pollutants are briefly discussed.

[Determination of fluoroacetic acid in human blood and urine by accelerated solvent extraction-ion chromatography-mass spectrometry].

Fluoroacetic acid is a highly polar poison used for rodent control. When ingested by the human body, it seriously damages nerve cells and heart tissues and even causes death by cardiac arrest or respiratory failure. Common detection methods for fluoroacetic acid include gas chromatography-mass spectrometry and liquid chromatography-mass spectrometry, both of which require complex pretreatment methods, such as derivatization. In this study, a method to determine fluoroacetic acid in human blood and urine based on accelerated solvent extraction-ion chromatography-mass spectrometry (ASE-IC-MS) was established. Two pretreatment methods, namely, acetonitrile precipitation and accelerated solvent extraction, were compared. Furthermore, the effects of different extraction conditions, such as the extraction time, extraction temperature, and number of cycles, were investigated. The most suitable chromatographic separation conditions, such as the chromatographic column, column temperature, and elution procedure, were determined, and the MS conditions, such as the collision energy (CE) and declustering potential (DP) of the ion pairs of the target compound, were investigated. Based on the experimental results, the optimal pretreatment methods and detection conditions were obtained, and reliable data were collected. Deionized water was used as the extraction solvent, and blood and urine samples were processed by accelerated solvent extractor. The supernatant was sequentially collected via centrifugal ultrafiltration and 0.22 µm membrane filtration, diluted 50 times, and then injected into the chromatographic column for detection. An Ion Pac AS20 IC column was used for isocratic elution with 15.0 mmol/L KOH solution as the eluent. The effluent was passed through a suppressor and into a triple quadrupole mass spectrometer, which was used to perform MS/MS (ESI-) in multiple reaction monitoring (MRM) mode. The quantitative ion was m/z 77.0>57.0 when the CE and DP were -15.0 eV and -20.0 V, respectively. An external standard method was used for quantitative analysis. The results showed a good linear relationship for fluoroacetic acid in the range of 0.5-500.0 µg/L (r>0.999), with limits of detection (LOD) and quantification (LOQ) of 0.14 and 0.47 µg/L, respectively. The recoveries of fluoroacetic acid in blood and urine were 93.4%-95.8% and 96.2%-98.4%, respectively. The intra-day RSDs for blood and urine were 0.8%-1.6% and 0.2%-1.0%, respectively, while the inter-day RSDs were 2.3%-3.8% and 3.9%-6.9%, respectively. Further investigation revealed that the matrix effects of this method in blood and urine, at -7.4% and -3.0%, respectively, were fairly weak. The established method was successfully applied to detect fluoroacetic acid in human blood and urine obtained from a poisoning case, and the results obtained provided crucial clues that led to swift case resolution. The efficiency of the method was significantly higher than that of conventional detection methods. In conclusion, the developed method has high sensitivity and good repeatability and is suitable for the rapid detection of fluoroacetic acid in human blood and urine. Moreover, because this method does not require derivatization, it is simple and efficient.

Analysis of degradation products of nerve agents in biological fluids by ion chromatography-tandem mass spectrometry.

PURPOSE: The detection of hydrolysis products of nerve agents (alkyl methylphosphonic acids; RMPAs) in biological samples from victims is important to confirm exposure to nerve agents. However, analysis of RMPAs is difficult due to their high hydrophilicity. The aim of this study was to develop ion chromatography-tandem mass spectrometry (IC-MS/MS) methods using commercially available equipment and columns to analyze RMPAs in human urine and serum with high sensitivity and without using complicate techniques. METHODS: A Dionex IonPac AS11-HC anion-exchange column was used to analyze six RMPAs (MPA, EMPA, IMPA, iBuMPA, CHMPA, and PMPA). For pretreatments of biological fluids, we developed two pretreatment methods (Method 1: dilution and ultrafiltration; Method 2: removal of chloride ions with Ag cartridges). RESULTS: Six RMPAs including highly hydrophilic methylphosphonic acid and ethyl methylphosphonic acid could be analyzed with sufficient retention times and peak shape. The detection limits of RMPAs were improved using Dionex OnGuard II Ba/Ag/H cartridges and MetaSEP IC-Ag cartridges (urine: 0.5-5 ng/mL; serum: 1-5 ng/mL). These methods were also applied to the test samples for the Organisation for the Prohibition of Chemical Weapons Biomedical Proficiency Tests. CONCLUSIONS: RMPAs could be sufficiently analyzed by IC-MS/MS. In addition, the limits of detection were superior to those obtained in our previous study involving LC-MS/MS or derivatization-LC-MS/MS method. For analysis of biological samples, an appropriate pretreatment method can be chosen according to the amount of sample available for analysis and expected RMPA concentrations.

Coupling an ion chromatography to high resolution mass spectrometry (IC-MS) for the discovery of potentially prebiotic oligosaccharides in Chardonnay grape marc.

Oligosaccharides are carbohydrates made of three to twenty monosaccharide units linked through glycosidic bonds. Emerging research into the potential prebiotic activity of oligosaccharides is creating opportunities to use industrial byproducts as value-added products. Grape marc is a residue left after winemaking and has been shown to provide health benefits to humans. In this study, we analyzed the oligosaccharides in Chardonnay grape marc by utilizing a hyphenated platform in which an ion chromatography (IC) system is coupled to an Orbitrap mass spectrometer (MS). With this platform, we obtained a structural library including 32 oligosaccharides with unique compositions of monosaccharides and 61 oligosaccharide structures. Notably, the ion chromatographic separation provided resolution of charged isomers while maintaining separation capacity for small, neutral oligosaccharides. High-quality tandem MS also facilitated the identification of oligosaccharides with structural modifications including methylation and the presence of sugar alditols and hexuronic acids. The data acquired by the IC-MS system were also compared with previously published LC-MS data. We found that these two platforms are largely complementary and, in combination, provide a more comprehensive characterization of oligosaccharides than either platform achieves alone.

[Determination of 10 organic acids in alcoholic products by ion chromatography-tandem mass spectrometry].

A method was developed for the determination of 10 organic acids in liquor, yellow rice wine, and dry red wine by ion chromatography-triple quadrupole mass spectrometry (IC-MS/MS). First, the liquor samples were diluted with deionized water, degassed with nitrogen, and analyzed by IC-MS/MS. Then, the yellow rice wine and dry red wine samples were purified with different solid-phase extraction cartridges. Finally, the GCB solid-phase extraction cartridge was selected for purification, diluted with deionized water, and analyzed by IC-MS/MS. The samples were separated using a Dionex IonPac AS11-HC anion analysis column with high capacity and strong hydrophilicity, with an KOH aqueous solution as the eluent, which was produced by an automatic generator for gradient elution. After being suppressed using a suppressor, the eluent was injected directly into the electrospray ionization tandem mass spectrometry (ESI-MS/MS), ionized in negative ion mode, detected in multiple reaction monitoring (MRM) mode, and quantified using an external standard method. Oxalic acid, fumaric acid, maleic acid, malic acid, tartaric acid, citric acid, quinic acid, and aconitic acid showed good linear relationships in the range of 0.05-2 mg/L. Succinic acid and lactic acid showed good linearities in the range of 0.05-5 mg/L and 0.05-10 mg/L, respectively. The correlation coefficients (r2) were >0.99. The limits of detection (LODs) and limits of quantification (LOQs) were 1.0-8.0 µg/L and 3.5-26.5 µg/L, respectively. The average recoveries ranged from 83.0% to 112.1%, and the relative standard deviations (RSDs) were <9.1% in spiked samples at three levels. The proposed method allowed easy pretreatment without using organic solvents or derivatization processing. Overall, the proposed method is accurate, rapid, sensitive, and it is suitable for the qualitative and quantitative analyses of the 10 organic acids in three wine samples. Moreover, it can be used for the determination of flavor and quality of alcoholic products.

Analysis of Biogenic Amines Using Immunoassays, HPLC, and a Newly Developed IC-MS/MS Technique in Fish Products-A Comparative Study.

In this study, comparative analyses were carried out with ion chromatography mass-spectrometry (IC-MS/MS) which has no derivatization step, high-performance liquid chromatography (HPLC) technique, as well as two quantitative and two semi-quantitative immunoassays. The results demonstrated that HPLC and quantitative immunoassay methods were well-correlated with IC-MS/MS in determining histamine in various types of fish products. The best correlation was observed with the HistaSure ELISA Fast Track kit (R2 = 0.9903). More than half of the values (68%) obtained by two methods were also statistically similar. The results of semi-quantitative test kits also supported histamine values estimated by quantitative methods, with some exceptions. The best results were found for HistaSure Lateral Flow in supporting the quantitative techniques. Therefore, these methods are found suitable for monitoring histamine in fish products in terms of food safety. Good correlations were also observed HPLC and IC-MS/MS in determining cadaverine, putrescine, and tyramine with the highest value observed for tyramine as R2 = 0.9785. However, no correlation was observed for other biogenic amines, and the majority of the results were significantly different from each other for these amines (p < 0.05). The differences may be caused by the drawbacks reported previously for HPLC. However, further studies are required to confirm the possible effects. This study provides a comparative evaluation of several methods in terms of their suitability in determining biogenic amines in fish products for both monitoring and regulatory purposes.

Determination of phosphite (HPO3-2) by a new IC/MS/MS method using an 18O-labeled HPO3-2 internal standard.

A new method has been developed to determine trace amounts of phosphite (HPO3-2) in environmental samples using ion chromatography with electrospray tandem mass spectrometry (IC-ESI/MS/MS). The method includes the production and use of an 18O-labeled HPO3-2 internal standard (IS). This isotopically labeled IS significantly improved sensitivity and could account for matrix suppression. The method detection limit (MDL) was determined as 0.017 and 0.034 µg L-1 of HPO3-2 (6.5 and 13 ng P L-1) using a 500 and 25 µL injection loop, respectively. Precision (1-10%) and accuracy (recoveries = 96-106%) were established for a range of environmental samples using known (spiked) addition. The impact of ionic interferences was investigated by evaluating the response of the internal standard in the presence of common anions with respect to distilled deionized water. The most significant interference was due to nitrate (100 mg-NO3- L-1) with a 99.99% reduction in IS intensity. The method was successfully applied to wastewater effluent, surface water, tap water, and soil samples. Relatively low concentrations <0.25 µg HPO3-2 L-1 were measured in tap water, surface water and wastewater effluent, and ~1.6 µg kg-1 HPO3-2 in soil samples, using both injection loops. Limited suppression was observed for all matrices. The largest IS peak area suppression (~98%) was observed in WW effluent with 500 µL injection loop; however, this method was able to quantify HPO3-2 with good recoveries and precision despite the mentioned suppression, supporting the ability of the proposed method to quantify HPO3-2 in different environmental matrices.

Quantification of glyphosate and other organophosphorus compounds in human urine via ion chromatography isotope dilution tandem mass spectrometry.

Organophosphorus pesticides are the most used pesticides in the United States. Most organophosphorus pesticides are composed of a phosphate (or phosphorothioate or phosphorodithioate) moiety and a variable organic group. Organophosphorus pesticides are scrutinized by regulatory bodies and agencies because of their toxicity or suspected carcinogenicity. Upon exposure, organophosphorus pesticides and their metabolites eliminate in urine; these urinary biomarkers are useful to evaluate human exposure. We developed a method using stable isotope dilution, ion chromatography tandem mass spectrometry for quantification in urine of 6 O,O-dialkylphosphates, metabolites of organophosphorus insecticides, and glyphosate, the most used herbicide in the United States. With simple and minimal sample preparation, the analytical method is selective and sensitive (limits of detection are 0.2-0.8 µg/L), accurate (>85%) and precise (relative standard deviation <20%), depending on the analyte. To assess the suitability of the method in real exposure scenarios, we analyzed samples collected anonymously from subjects with suspected exposure to pesticides (n = 40) or who had been on an organic diet (n = 50). We detected glyphosate in 80% of subjects reporting an organic diet and in 78% of those with suspected glyphosate exposure; concentrations ranged from <0.2 to 28.6 µg/L. Median concentrations were 0.39 µg/L for the organic diet group and 0.40 µg/L for individuals with suspected exposure. Interestingly, interquartile ranges were considerably higher among those reporting pesticide exposure (0.63 µg/L) than those consuming organic diets (0.42 µg/L). These data suggest that the method meets typical validation benchmark values and is sensitive to investigate background exposures in the general population.

Determination of monosaccharides hydrolyzed from polysaccharides in activated sludge by ion chromatography-mass spectrometry with online pretreatment of column switching technique.

The simultaneous determination of monosaccharides present in the activated sludge would be crucial to understand the water treatment mechanism. Herein, an ion chromatography-mass spectrometry (IC-MS) with online pretreatment of column switching technique was proposed to analyze monosaccharides hydrolyzed from extracellular polysaccharides in the activated sludge. When the matrix was eliminated in the first dimension, monosaccharides were immediately identified by IC-MS. The improved ionization efficiency was achieved with the addition of T-joint prior to MS. During the performance test, our established method showed excellent detection limits ranging from 0.34 to 2.15 µg/L for all sugar targets. Great linearity (R ≥ 0.9955) was also achieved using this method in the range from 0.01 to 5 mg/L. Furthermore, the average recoveries were obtained between 84.82 and 113.46%. RSDs for peak areas and retention times were determined as 3.76% and 0.27%, respectively. Finally, this approach provided a rapid, convenient, and practical determination of monosaccharides in the activated sludge, which would be helpful for the analysis of monosaccharides derived from other biological samples.

An innovative derivatization-free IC-MS/MS method for the detection of bisphosphonates in horse plasma.

Bisphosphonates are prohibited drugs according to Article 6 of the International Agreement on Breeding, Racing and Wagering of the International Federation of Horseracing Authorities (IFHA) and the International Equestrian Federation (FEI). These compounds are used for the treatment of lameness, navicular and bone diseases in horses and are divided into two groups: non-nitrogen-containing bisphosphonate drugs (e.g. clodronic acid) and nitrogen-containing bisphosphonate drugs (e.g. zoledronic acid). Their hydrophilic properties and the high affinity for the bone matrix make the control of their use quite difficult. Current analytical strategies to detect such compounds often rely on a solid phase extraction (SPE) followed by detection by means of UHPLC-MS/MS after methylation with chemical reagents. To improve the analysis throughput and to eliminate the need for chemical derivatization, an innovative 96-well SPE followed by ion chromatography-mass spectrometry was developed. Analyses are conducted on an ICS-6000 HPIC system coupled to a TSQ Altis™ (Thermo Scientific™). The use of a 96-well SPE allowed 5-fold sample increase and a 6-fold throughput improvement. While preliminary results conducted on horse plasma exhibited similar performances to the method for the detection of non-nitrogen-containing bisphosphonates, the analytical performances of nitrogen-containing bisphosphonates were greatly improved.

Selective and sensitive determination of bromate in bread by ion chromatography-mass spectrometry.

Potassium bromate is a food additive used as "flour improver" in the baking industry. Bromate is considered a carcinogenic and nephrotoxic substance. Thus, the bromate concentration must be carefully monitored in flour products. We developed a method for a selective and sensitive determination of bromate in flour that uses ion chromatography coupled with single quadrupole mass spectrometry (IC -MS). A recently introduced high-capacity anion-exchange column was used to separate bromate from matrix anions. Six commercial flour and flour products including homemade bread baked using flour containing potassium bromate, were analyzed. The method showed good precision with RSDs <0.2%, and <5% (n = 8), for retention time and peak area respectively. Bromate recoveries from flour samples ranged from 86 to 110%. The limits of detection and quantitation of bromate in the prepared solution were 0.10 µg/L and 0.34 µg/L, respectively, which corresponded to 5 µg/kg and 17 µg/kg in bread.

Analysis of perchlorate in baby food on Canadian (Ottawa) markets in 2009 and estimated dietary exposure.

In order to determine the baseline levels of perchlorate in major brands of baby food, 200 baby food products were collected from retail stores in Ottawa, Canada and analysed for perchlorate in 2010. The seven food groups tested were fruit, juices, vegetables, meat, yogurt, mixed (vegetable mixed with meat) and other (e.g. vegetable mixed with meat and cereal, cheese, egg,). Samples were extracted with a mixture of methanol and 1% acetic acid (4:1, v/v). Determination was conducted by stable isotope dilution ion chromatography tandem mass spectrometry (ID-IC-MS/MS). The complexity of different food matrices required additional method validation. The perchlorate levels in 46 samples were found to be lower than the quantification limit (0.2 ng g-1). The perchlorate levels in the other 154 baby food samples were also low; about 96.7% of the baby foods had perchlorate levels less than 10 ng g-1 (ranged from 0.2 to 22.4 ng g-1, median1.35 ng g-1); only 5 samples had perchlorate levels higher than 10 ng g-1. Dietary exposure to perchlorate from analysed baby food was conservatively estimated to range from 0.007 to 0.121 µg/kg bw/d based on the mean intake for children (1-5 years old).

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.

Assessment of capillary anion exchange ion chromatography tandem mass spectrometry for the quantitative profiling of the phosphometabolome and organic acids in biological extracts.

Metabolic profiling has become an important tool in biological research, and the chromatographic separation of metabolites coupled with mass spectrometric detection is the most frequently used approach for such studies. The establishment of robust chromatographic methods for comprehensive coverage of the anionic metabolite pool is especially challenging. In this study, the development of a capillary ion exchange chromatography (capIC) - negative ESI tandem mass spectrometry (MS/MS) workflow for the quantitative profiling of the phosphometabolome (e.g., sugar phosphates and nucleotides) is presented. The chromatographic separation and MS/MS conditions were optimized, and the precision of repetitive injections and accuracy in terms of error percentage to true concentration were assessed. The precision is excellent for a capillary flow system with an average CV% of 8.5% for a 50-fmol standard injection and in the lower 2.4-4.4% range for higher concentrations (500-7,500 fmol). The limit of detection (LOD) ranges from 1 to 100 nM (5-500 fmol injected on column), and the limit of quantitation (LOQ) ranges from 1 to 500 nM (5-2,500 fmol injected on column). A fast gradient method with the injection of 50% methanol in water between analytical samples is needed to eliminate carry-over and ensure optimal re-equilibration of the column. Finally, the quantitative applicability of the system was tested on real biological matrices using the constant-volume standard addition method (SAM). Extracts of the human kidney Hek293 cell line were spiked with increasing concentrations of standards to determine the concentration of each metabolite in the sample. Forty-four metabolites were detected with an average uncertainty of 4.1%. Thus, the capIC-MS/MS method exhibits excellent selectivity, sensitivity and precision for the quantitative profiling of the phosphometabolome.