Liquid Chromatography Inductively Coupled Plasma Mass Research Articles

The Fast Quantification of Vitamin B12 in Milk Powder by High-Performance Liquid Chromatography-Inductively Coupled Plasma Mass Spectrometry.

This study presents a new technique for determining vitamin B12 in milk powder using high-performance liquid chromatography-inductively coupled plasma mass spectrometry (HPLC-ICP-MS). We used ultrasonics with potassium ferrocyanide and zinc acetate solutions to extract the samples. 59Co was employed as the analytical target for cyanocobalamin. It was separated using a Phenomenex Luna 5 μm C18 (250 × 4.6 mm) chromatographic column with a mobile phase consisting of 1.6 mmol/L EDTA and 0.4 mmol/L KH2PO4 in a 60% v/v methanol solution (pH = 4.0). The sample has an excellent separating degree for free cobalt and cyanocobalamin, and isocratic elution can be finished within 4.0 min. To eliminate the matrix interference due to the presence of milk powder, we applied collision mode (KED). The linear range of cyanocobalamine ranged from 1.0 μg/L to 20 μg/L, with correlation coefficients (r2) of 0.9994. The limit of detection (LOD) was 0.63 μg/kg, and the limit of quantitation (LOQ) was 2.11 μg/kg. The mean recoveries were in the range of 87.4-103.6%. The accuracy and precision of the developed method are well suited for the fast quantification of the trace vitamin B12 in milk powder.

Optimized mercury speciation analysis using LC-ICP-MS and microwave assisted extraction for precise determination of methylmercury in fish, rice and soil

Mercury (Hg) is a toxic element that exists in various forms, each with its characteristics and impacts on the environment. Methylmercury (MeHg) bioaccumulates in the food chain and identifying mercury species is crucial to assessing risks to ecology and health. Therefore, accurate, sensitive, and broad-range analytical methods are essential for the determination of methylmercury. This study optimized and validated a procedure for Hg speciation analysis in rice, fish, and soil using different extractants, followed by liquid chromatography inductively-coupled plasma mass spectrometry (LC ICP-MS) using certified references. Microwave-assisted extraction (MAE) parameters were optimized using 25 % KOH, resulting in improved sensitivity, accuracy and processing time. The validated method achieved a limit of quantitation (LOQ) of 12 µg kg−1 and showed acceptable percentage recoveries (75.3–98.1 %) in all matrices, enabling precise determination of MeHg (%RSDr; 3.76–5.78, %RSDR; 2.34–6.75) and Hg in a large number of samples within a short time frame. The validated method is particularly well-suited for rice, followed by fish and then soil. Therefore, the method utilizing microwave-assisted extraction and LC ICP-MS ensures precise methylmercury determination in rice, fish, and soil, crucial for evaluating environmental and health risks associated with mercury bioaccumulation.

Quantitative Separation of Unknown Organic-Metal Complexes by Liquid Chromatography-Inductively Coupled Plasma-Mass Spectrometry.

Dissolved organic matter (DOM) is widely recognized to control the solubility and reactivity of trace metals in the environment. However, the mechanisms that govern metal-DOM complexation remain elusive, primarily due to the analytical challenge of fractionating and quantifying metal-organic species within the complex mixture of organic compounds that comprise DOM. Here, we describe a quantitative method for fractionation and element-specific detection of organic-metal complexes using liquid chromatography with online inductively coupled plasma mass spectrometry (LC-ICP-MS). The method implements a post-column compensation gradient to stabilize ICP-MS elemental response across the LC solvent gradient, thereby overcoming a major barrier to achieving quantitative accuracy with LC-ICP-MS. With external calibration and internal standard correction, the method yields concentrations of organic-metal complexes that were consistently within 6% of their true values, regardless of the complex's elution time. We used the method to evaluate the effects of four stationary phases (C18, phenyl, amide, and pentafluoroylphenyl propyl) on the recovery and separation of environmentally relevant trace metals (Mn, Fe, Co, Ni, Cu, Zn, Cd, and Pb) in Suwannee River Fulvic Acid and Suwannee River Natural Organic Matter. The C18, amide, and phenyl phases generally yielded optimal metal recoveries (>75% for all metals except Pb), with the phenyl phase separating polar species to a greater extent than C18 or amide. We also fractionated organic-bound Fe, Cu, and Ni in oxidized and reduced soils, revealing divergent metal-DOM speciation across soil redox environments. By enabling quantitative fractionation of DOM-bound metals, our method offers a means for advancing a mechanistic understanding of metal-organic complexation throughout the environment.

Slow Kinetics of Iron Binding to Marine Ligands in Seawater Measured by Isotope Exchange Liquid Chromatography-Inductively Coupled Plasma Mass Spectrometry.

Current understanding of dissolved iron (Fe) speciation in the ocean is based on two fundamentally different approaches: electrochemical methods that measure bulk properties of a heterogeneous ligand pool and liquid chromatography mass spectrometry methods that characterize ligands at a molecular level. Here, we describe a method for simultaneously determining Fe-ligand dissociation rate constants (kd) of suites of naturally occurring ligands in seawater by monitoring the exchange of ligand-bound 56Fe with 57Fe using liquid chromatography-inductively coupled mass spectrometry. Values of kd were determined for solutions of ferrichrome and ferrioxamine E. In seawater, the dissociation rate constant of ferrichrome (kd = 10 × 10-8 s-1) was greater than that of ferrioxamine E (kd = 3.6 × 10-8 s-1). The rates for both compounds were over twice as fast in seawater compared with pure water, suggesting that seawater salts accelerate dissociation. Isotope exchange experiments on organic extracts of natural seawater indicated that ligand-binding sites associated with chromatographically unresolved dissolved organic matter exchanged Fe more quickly (kd = 1.8 × 10-5 s-1) than amphibactin siderophores (kd = 2.15 × 10-6 s-1) and an unidentified siderophore with m/z 709 (kd = 9.6 × 10-6 s-1). These findings demonstrate that our approach can bridge molecular-level ligand identification with kinetic and thermodynamic metal-binding properties.

Simultaneous Species Analysis of Arsenic, Selenium, Bromine, and Iodine in Bottled Drinking Water and Fruit Juice by High-Performance Liquid Chromatography-Inductively Coupled Plasma Mass Spectrometry.

A method for the simultaneous determination of arsenobetaine, arsenite, arsenate, dimethylarsinic acid, monomethylarsonic acid, selenite, selenate, bromate, bromide, iodate, and iodide in bottled drinking water and fruit juice samples was established by using high-performance liquid chromatography-inductively coupled plasma mass spectrometry. The separation of eleven compounds was performed on an ion exchange chromatography column (Dionex IonPac AS14) with 20 mmol L-1 (NH4)2CO3 (pH 10) and 50 mmol L-1 (NH4)2CO3 (pH 10) as a mobile phase. The limits of quantification of the method were 0.17 - 1.2 μg L-1 for the test compounds in bottled drinking water and 0.34 - 2.4 μg L-1 in fruit juice. The average recoveries ranged from 85.8 to 102.2%, and the relative standard deviations (RSDs) obtained in fortification recovery studies were generally <4.2% for bottled drinking water samples. The average recoveries ranged from 88.1 to 118.0% (except for iodate) for fruit juice sample.

A simple spectrophotometric method for rapid quantitative screening of arsenic bio-transforming bacteria

Abstract A simple spectrophotometric technique for inorganic arsenic speciation of known total arsenic has been developed for application in quantitative screening of arsenite-oxidizing and arsenate-reducing bacteria from the wide range of environmental isolates. The technique is based on the spectrophotometric absorbance measurement of the color intensity in the arsenic and potassium permanganate mixture. Since arsenate does not react with potassium permanganate, the intensity of color decreases proportionately with the increasing concentration of arsenite in the total arsenic. The speciation method can be used over a pH range of 4–9. The validity of the results obtained from this spectrophotometric method was confirmed with the Liquid Chromatography-Inductively Coupled Plasma-Mass Spectrometry (LC-ICP-MS). This method has great potential for the screening of arsenite-oxidizing bacteria.

A Study of Bromine Speciation in Human Serum and Ambroxol Determination in Rat Plasma by Liquid Chromatography–Inductively Coupled Plasma Mass Spectrometry

In this study, we employed liquid chromatography–inductively coupled plasma mass spectrometry (LC–ICP-MS) to explore bromine bioforms in human serum. Three bromine species were found by size exclusion chromatography–inductively coupled plasma mass spectrometry (SEC–ICP-MS), and one of the most abundant species was identified as Br− by anion exchange chromatography–inductively coupled plasma mass spectrometry (IC–ICP-MS).The quantitative detection of Br− was performed by SEC–ICP-MS, and the total bromine was detected by ICP-MS. Results for the determination of Br− and total bromine in human serum revealed that Br− is the major form of bromine in human serum, with a ratio ranging from 57.3 to 68.8%. Furthermore, we developed a method for the determination of ambroxol based on reversed phase high-performance liquid chromatography–inductively coupled plasma mass spectrometry (RP-HPLC–ICP-MS), and then applied it in rat plasma analysis. After optimization of the RP-HPLC–ICP-MS parameters and pre-treatment procedures, the retention time of ambroxol was 4.6 min and the detection limit was 7.0 μg L−1. The average recovery was 85.4%, with relative standard deviation of 8.4%. The above results showed that the RP-HPLC–ICP-MS method possessed the advantages of low matrix interference and time efficiency, which were better than those reported for traditional RP-HPLC methods. Therefore, this new method for the detection of ambroxol based on RP-HPLC–ICP-MS was certainly a good tool for ambroxol analysis.

Arsenic Speciation of Edible Shrimp by High-Performance Liquid Chromatography-Inductively Coupled Plasma-Mass Spectrometry (HPLC-ICP-MS): Method Development and Health Assessment

This study aimed at developing an accurate method for determining the levels of total arsenic (As) and arsenic species in edible shrimp with the collision/reaction cell (CRC) in the O2 mass-shift mode to remove interferences. The microwave-assisted extraction method demonstrated satisfactory efficiency (86.9%), and As species were separated rapidly within 11 min when the optimized chromatographic conditions were adopted. During the study, the limits of detection, precision, and spike recovery for six arsenic species were in the ranges from 0.010 to 0.028 μg/L, 1.89 to 3.14%, and 96.9 to 103.2%, respectively. The analytical methods were successfully applied to determine the concentrations of total arsenic and As species in eight shrimp samples. The results showed that arsenobetaine was the predominant As species, and inorganic arsenic contents were below 0.5 mg/kg in the shrimp samples analyzed. The health risk assessment indicated that the shrimp samples detected posed no particular risk of As to local consumers.

Quantitation of Selenomethionine in Multivitamins and Selenium Supplements by High Performance Liquid Chromatography Inductively-Coupled Plasma Mass Spectrometry

VITA-1 and VITB-1 multivitamin and mineral supplement candidate reference materials from the National Research Council Canada were analyzed for their total selenium and selenomethionine contents. Following a methanesulfonic acid reflux to extract selenomethionine from the selenized yeast in the multivitamins, analysis by high-performance liquid chromatography-inductively coupled plasma triple quadrupole mass spectrometry resulted in concentrations of 7.4 ± 3.0 μg SeMet g–1 and 16.4 ± 6.5 μg SeMet g−1 in VITA-1 and VITB-1, respectively. Twelve commercially available multivitamins and selenium supplements were analyzed following the same protocol. Seven of these were noted to contain 85–115% of the selenium stated on the label; the others ranged from 5 to 147% of the claimed amount. Only one multivitamin contained selenomethionine at a concentration above the detection limit, but the amount found in the selenium supplements matched the label claims within a reasonable level of uncertainty. For comparison, two certified reference materials—wheat gluten and egg powder, both certified for total selenium only—were also examined and it was determined that selenomethionine accounted for 58% and 25% of the selenium in these food products, respectively.

Snapshots of Iron Speciation: Tracking the Fate of Iron Nanoparticle Drugs via a Liquid Chromatography-Inductively Coupled Plasma-Mass Spectrometric Approach.

Nanomedicines are nanoparticle-based therapeutic or diagnostic agents designed for targeted delivery or enhanced stability. Nanotechnology has been successfully employed to develop various drug formulations with improved pharmacokinetic characteristics, and current research efforts are focused on the development of new innovator and generic nanomedicines. Nanomedicines, which are often denoted as complex or nonbiological complex drugs, have inherently different physicochemical and pharmacokinetic properties than conventional small molecule drugs. The tools necessary to fully evaluate nanomedicines in clinical settings are limited, which can hamper their development. One of the most successful families of nanomedicines are iron-carbohydrate nanoparticles, which are administered intravenously (IV) to treat iron-deficiency anemia. In the U.S., the FDA has approved six distinct iron-carbohydrate nanoparticles but only one generic version (sodium ferric gluconate for Ferrlecit). There is significant interest in approving additional generic iron-carbohydrate drugs; however, the lack of a direct method to monitor the fate of the iron nanoparticles in clinical samples has impeded this approval. Herein we report a novel liquid chromatography-inductively coupled plasma-mass spectrometry (LC-ICP-MS) method that allows for the direct quantification of the iron-carbohydrate drugs in clinical samples, while simultaneously measuring the speciation of the iron released from the nanoparticles in biological samples. To our knowledge, this is the first time that iron nanoparticles have been observed in clinical samples, opening the door for direct pharmacokinetic studies of this family of drugs. This method has potential applications not only for iron-nanoparticle drugs but also for any nanomedicine with an inorganic component.

Development of Simultaneous Analytical Method for Agricultural Chemicals in Raw Water for Drinking Water Supply by Gas Chromatography Mass Spectrometry, Liquid Chromatography Time-of-Flight Mass Spectrometry or Liquid Chromatography-Inductively Coupled Plasma Mass Spectrometry and Study on Degradabilities in Their Chlorination Process

Development of Simultaneous Analytical Method for Agricultural Chemicals in Raw Water for Drinking Water Supply by Gas Chromatography Mass Spectrometry, Liquid Chromatography Time-of-Flight Mass Spectrometry or Liquid Chromatography-Inductively Coupled Plasma Mass Spectrometry and Study on Degradabilities in Their Chlorination Process

Multilaboratory Validation of First Action Method 2016.04 for Determination of Four Arsenic Species in Fruit Juice by High-Performance Liquid Chromatography-Inductively Coupled Plasma-Mass Spectrometry.

Before being designated AOAC First Action Official MethodSM 2016.04, the U.S. Food and Drug Administration's method, EAM 4.10 High Performance Liquid Chromatography-Inductively Coupled Plasma-Mass Spectrometric Determination of Four Arsenic Species in Fruit Juice, underwent both a single-laboratory validation and a multilaboratory validation (MLV) study. Three federal and five state regulatory laboratories participated in the MLV study, which is the primary focus of this manuscript. The method was validated for inorganic arsenic (iAs) measured as the sum of the two iAs species arsenite [As(III)] and arsenate [As(V)], dimethylarsinic acid (DMA), and monomethylarsonic acid (MMA) by analyses of 13 juice samples, including three apple juice, three apple juice concentrate, four grape juice, and three pear juice samples. In addition, two water Standard Reference Materials (SRMs) were analyzed. The method LODs and LOQs obtained among the eight laboratories were approximately 0.3 and 2 ng/g, respectively, for each of the analytes and were adequate for the intended purpose of the method. Each laboratory analyzed method blanks, fortified method blanks, reference materials, triplicate portions of each juice sample, and duplicate fortified juice samples (one for each matrix type) at three fortification levels. In general, repeatability and reproducibility of the method was ≤15% RSD for each species present at a concentration >LOQ. The average recovery of fortified analytes for all laboratories ranged from 98 to 104% iAs, DMA, and MMA for all four juice sample matrixes. The average iAs results for SRMs 1640a and 1643e agreed within the range of 96-98% of certified values for total arsenic.

Quantitative Metabolite Profiling of an Amino Group Containing Pharmaceutical in Human Plasma via Precolumn Derivatization and High-Performance Liquid Chromatography-Inductively Coupled Plasma Mass Spectrometry.

Quantitative determination of the candidate drug molecule and its metabolites in biofluids and tissues is an inevitable step in the development of new pharmaceuticals. Because of the time-consuming and expensive nature of the current standard technique for quantitative metabolite profiling, i.e., radiolabeling followed by high-performance liquid chromatography (HPLC) with radiodetection, the development of alternative methodologies is of great interest. In this work, a simple, fast, sensitive, and accurate method for the quantitative metabolite profiling of an amino group containing drug (levothyroxine) and its metabolites in human plasma, based on precolumn derivatization followed by HPLC-inductively coupled plasma mass spectrometry (ICPMS), was developed and validated. To introduce a suitable "heteroelement" (defined here as an element that is detectable with ICPMS), an inexpensive and commercially available reagent, tetrabromophthalic anhydride (TBPA) was used for the derivatization of free NH2-groups. The presence of a known number of I atoms in both the drug molecule and its metabolites enabled a cross-validation of the newly developed derivatization procedure and quantification based on monitoring of the introduced Br. The formation of the derivatives was quantitative, providing a 4:1 stoichiometric Br/NH2 ratio. The derivatives were separated via reversed-phase HPLC with gradient elution. Bromine was determined via ICPMS at a mass-to-charge ratio of 79 using H2 as a reaction gas to ensure interference-free detection, and iodine was determined at a mass-to-charge ratio of 127 for cross-validation purposes. The method developed shows a fit-for-purpose accuracy (recovery between 85% and 115%) and precision (repeatability <15% RSD). The limit of quantification (LoQ) for Br was approximately 100 μg/L.

Determination of Total Arsenic and Speciation in Apple Juice by Liquid Chromatography–Inductively Coupled Plasma Mass Spectrometry: An Experiment for the Analytical Chemistry Laboratory

A two-part laboratory experiment was designed for upper-level analytical chemistry students to provide hands-on experience in the use of high performance liquid chromatography (HPLC) for separation and inductively coupled plasma mass spectrometry (ICP-MS) for detection. In the first part of the experiment, the students analyze total arsenic in apple juice purchased from local grocery stores using direct injection ICP-MS. In the second part, different species of arsenic in the same apple juice samples are determined using HPLC–ICP-MS. Quantification is performed based on two methods, standard addition and external calibration curve, to demonstrate how sample matrix can affect the accuracy of the analysis. The experiments provide the opportunity to introduce and/or review several fundamental analytical chemistry concepts: chromatographic separations, mass spectrometry, inductively couple plasma, matrix effects, calibration methods, internal standard, and basic statistical tests. Undergraduate students enrol...

Determination of Four Arsenic Species in Fruit Juice by High-Performance Liquid Chromatography-Inductively Coupled Plasma-Mass Spectrometry: Single-Laboratory Validation, First Action 2016.04.

Determination of Four Arsenic Species in Fruit Juice by High-Performance Liquid Chromatography-Inductively Coupled Plasma-Mass Spectrometry: Single-Laboratory Validation, First Action 2016.04.

Bioaccessibility and arsenic speciation in carrots, beets and quinoa from a contaminated area of Chile

Consumption of vegetables grown in arsenic (As)-contaminated soils is an important exposure route to the element for humans. The present study is focused on locally-grown, frequently-consumed vegetables, such as carrots (Daucus carota), beets (Beta vulgaris) and quinoa (Chenopodium) from the As-polluted Chiu Chiu area in Northern Chile. The latter region is affected both by As discharge from copper mining activity and natural As contamination, leading to a high As content in local food and water. For the selected vegetables, the following aspects were investigated: i) Their total As, Cu, Pb, Cr, Cd and Mn content; ii) Arsenic speciation in the edible part of the vegetables by liquid chromatography inductively-coupled plasma mass spectrometry (LC-ICPMS) analysis; iii) Arsenic bioaccessibility in the vegetables during in vitro gastrointestinal digestion; iv) Arsenic species present in the extracts obtained from in vitro gastrointestinal digestion; and v) Arsenic dietary exposure estimates for the assessment of the risk posed by the vegetables consumption.A significant degree of As contamination was found in the vegetables under study, their metal content having been compared with that of similar Spanish uncontaminated products. In vitro gastrointestinal digestion of the studied vegetables led to quantitative extraction of As from carrots and beets, whereas efficiency was about 40% for quinoa. For carrots, only As(III) and As(V) species were found, being their concentration levels similar. In the case of quinoa, around 85% of the element was present as As(V). For beets, inorganic As(V) and unknown overlapped As species (probably arsenosugars) were found. No significant transformation of the original As species was observed during in vitro gastrointestinal digestion. Arsenic dietary exposure values obtained for the three vegetables (0.017–0.021μg As person−1day−1) were much lower than the JFCFA's safety limit of 50μg As person−1day−1. Therefore, no toxicological risk would be expected from the intake of these vegetables.

Software Solution for Post-Column Isotope Dilution Liquid Chromatography–Inductively Coupled Plasma Mass Spectrometry

The application of isotope dilution in high performance liquid chromatography (HPLC) and inductively-coupled plasma mass spectrometry (ICP-MS) represents an important tool for elemental speciation analysis. Currently commercially available software deals only with one type of HPLC-ID-ICP-MS measurement comprising an addition of isotope-enriched species into the sample before HPLC separation, that is, species-specific isotope dilution. However, there is another possibility: species-unspecific isotope dilution, which is, unfortunately, not easily employed by common software. In this method, the isotope enriched solution containing common inorganic compound of the analyzed element is added to the sample after HPLC separation. Here a novel software system addresses this problem. The most important features of the computer program include easy operation, data adjustment by smoothing, detector dead-time correction, mass discrimination correction, background correction, integration of peak area and ID enumeration, processing of multi-elemental analyses, a choice of various isotopes, and a database of isotope abundances. The reliability of the software was demonstrated by processing of artificial chromatographic data and real chromatograms of standard reference materials containing mercury species and mixtures of selenium species.

LC/ICP/MSによる水道原水中における有機リン系農薬の分析法の開発

LC/ICP/MSによる水道原水中における有機リン系農薬の分析法の開発

Protein Quantitation Using Ru-NHS Ester Tagging and Isotope Dilution High-Pressure Liquid Chromatography–Inductively Coupled Plasma Mass Spectrometry Determination

An accurate, simple, and sensitive method for the direct determination of proteins by nonspecies specific isotope dilution and external calibration high-performance liquid chromatography-inductively coupled plasma mass spectrometry (HPLC-ICPMS) is described. The labeling of myoglobin (17 kDa), transferrin (77 kDa), and thyroglobulin (670 kDa) proteins was accomplished in a single-step reaction with a commercially available bis(2,2'-bipyridine)-4'-methyl-4-carboxybipyridine-ruthenium N-succinimidyl ester-bis(hexafluorophosphate) (Ru-NHS ester). Using excess amounts of Ru-NHS ester compared to the protein concentration at optimized labeling conditions, constant ratios for Ru to proteins were obtained. Bioconjugate solutions containing both labeled and unlabeled proteins as well as excess Ru-NHS ester reagent were injected onto a size exclusion HPLC column for separation and ICPMS detection without any further treatment. A (99)Ru enriched spike was used for nonspecies specific ID calibration. The accuracy of the method was confirmed at various concentration levels. An average recovery of 100% ± 3% (1 standard deviation (SD), n = 9) was obtained with a typical precision of better than 5% RSD at 100 μg mL(-1) for nonspecies specific ID. Detection limits (3SD) of 1.6, 3.2, and 7.0 fmol estimated from three procedure blanks were obtained for myoglobin, transferrin, and thyroglobulin, respectively. These detection limits are suitable for the direct determination of intact proteins at trace levels. For simplicity, external calibration was also tested. Good linear correlation coefficients, 0.9901, 0.9921, and 0.9980 for myoglobin, transferrin, and thyroglobulin, respectively, were obtained. The measured concentrations of proteins in a solution were in good agreement with their volumetrically prepared values. To the best of our knowledge, this is the first application of nonspecies specific ID for the accurate and direct determination of proteins using a Ru-NHS ester labeling reagent.

Determination of Mercury Compounds in Water Samples by Liquid Chromatography–Inductively Coupled Plasma Mass Spectrometry With anIn Situ Nebulizer/Vapor Generator

A preliminary study of a cold vapor generation system as the sample introduction device for liquid chromatography–inductively coupled plasma mass spectrometry (LC–ICP-MS) is described. Samples containing ionic mercury compounds were subjected to chromatographic separation before injection into the cold vapor generator. The species studied include inorganic mercury (Hg II ), methylmercury and ethylmercury. The sensitivity, detection limits and repeatability of the LC–ICP-MS system with a cold vapor generator were comparable to or better than those for an LC–ICP-MS system with conventional pneumatic nebulization or other sample introduction techniques. The limits of detection for various mercury species were in the range 0.03–0.11 ng ml -1 Hg based on peak height. The concentrations of mercury compounds in open ocean sea-water reference material NASS-4 and a tap water sample collected from National Sun Yat-Sen University were determined.