Capillary Electrophoresis-inductively Coupled Plasma Mass Spectrometry Research Articles

Dynamic Stomach Model-Capillary Electrophoresis-ICPMS for Evaluation of Release and Transformation Behaviors of Arsenic Species from Microplastics during Digestion.

Microplastics (MPs) can act as carriers of environmental arsenic species into the stomach with food and release arsenic species during digestion, which threatens human health. Herein, an integrated dynamic stomach model (DSM)-capillary electrophoresis-inductively coupled plasma mass spectrometry (CE-ICPMS) is developed for online monitoring of the release and transformation behaviors of arsenic species loaded on MPs (As-MPs) in the simulated human stomach. The 3D-printed DSM with a soft stomach chamber enables the behaviors of gastric peristalsis, gastric and salivary fluid addition, pH adjustment, and gastric emptying (GE) to be controlled by a self-written program after oral ingestion of food with As-MPs. The gastric extract during digestion is introduced into the spiral channel to remove the large particulate impurity and online filtered to obtain the clarified arsenic-containing solution for subsequent speciation analysis of arsenic by CE-ICPMS. The digestion conditions and pretreatment processes of DSM are tracked and validated, and the release rates of As-MPs digested by DSM are compared with those digested by the static stomach model and DSM without GE. The release rate of inorganic arsenic on MPs is higher than that of organic arsenic throughout the gastric digestion process, and 8% of As(V) is reduced to As(III). The detection limits for As(III), DMA, MMA, and As(V) are 0.5-0.9 μg L-1 using DSM-CE-ICPMS, along with precisions of ≤8%. This present method provides an integrated and convenient tool for evaluating the release and transformation of As-MPs during human gastric digestion and provides a reference for exploring the interactions between MPs and metals/metalloids in the human body.

Influence of gluconate on the retention of Eu(III), Am(III), Th(IV), Pu(IV), and U(VI) by C-S-H (C/S = 0.8)

The retention of actinides in different oxidation states (An(X), X = III, IV, VI) by a calcium-silicate-hydrate (C-S-H) phase with a Ca/Si (C/S) ratio of 0.8 was investigated in the presence of gluconate (GLU). The actinides considered were Am(III), Th(IV), Pu(IV), and U(VI). Eu(III) was investigated as chemical analogue for Am(III) and Cm(III). In addition to the ternary systems An(X)/GLU/C-S-H, also binary systems An(X)/C-S-H, GLU/C-S-H, and An(X)/GLU were studied. Complementary analytical techniques were applied to address the different specific aspects of the binary and ternary systems. Time-resolved laser-induced luminescence spectroscopy (TRLFS) was applied in combination with parallel factor analysis (PARAFAC) to identify retained species and to monitor species-selective sorption kinetics. 13C and 29Si magic-angle-spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy and X-ray photoelectron spectroscopy (XPS) were applied to determine the bulk structure and the composition of the C-S-H surface, respectively, in the absence and presence of GLU. The interaction of Th(IV) with GLU in different electrolytes was studied by capillary electrophoresis-inductively coupled plasma mass spectrometry (CE-ICP-MS). The influence of GLU on An(X) retention was investigated for a large concentration range up to 10−2 M. The results showed that GLU had little to no effect on the overall An(X) retention by C-S-H with C/S of 0.8, regardless of the oxidation state of the actinides. For Eu(III), the TRLFS investigations additionally implied the formation of a Eu(III)-bearing precipitate with dissolved constituents of the C-S-H phase, which becomes structurally altered by the presence of GLU. For U(VI) sorption on the C-S-H phase, only a small influence of GLU could be established in the luminescence spectroscopic investigations, and no precipitation of U(VI)-containing secondary phases could be identified.

CE-ICP-MS to probe Aβ1-42/copper (II) interactions, a complementary tool to study amyloid aggregation in Alzheimer's disease.

Copper (II) ions appear to be involved in the Alzheimer's disease and seem to influence the aggregation of the amyloid-β1-42 (Aβ1-42) peptide. However, data are not conclusive and still not subject to consensus, copper (II) being suspected to either promote or inhibit aggregation. To address this question, CE-ICP-MS (capillary electrophoresis-inductively coupled plasma-mass spectrometry) hyphenation was proposed as a complementary tool to follow the distribution of copper in the different oligomeric forms, at different substoichiometries and different incubation times. Results clearly indicated the formation of several negatively charged copper complexes and showed the enhancement of the aggregation rate with copper concentration. Moreover, the variations of copper (II) speciation suggest different aggregation pathway, even for substoichiometric ratios.

Determination of the Stability Constants of the Acetate Complexes of the Actinides Am(III), Th(IV), Np(V), and U(VI) Using Capillary Electrophoresis-Inductively Coupled Plasma Mass Spectrometry.

Capillary electrophoresis-inductively coupled plasma mass spectrometry (CE-ICP-MS) was used to determine the stability constants of the actinides Am(III), Th(IV), Np(V), and U(VI) at an ionic strength of I = 0.3 M. The obtained stability constants were extrapolated to zero ionic strength by means of the Davies equation. For both U(VI) and Am(III), three consecutive acetate complexes with log(β10) = 3.01 ± 0.12, log(β20) = 5.27 ± 0.07, log(β30) = 6.82 ± 0.09, and log(β10) = 3.70 ± 0.09, log(β20) = 5.35 ± 0.08, log(β30) = 6.45 ± 0.09, respectively, could be identified. For Np(V), there was just one acetate complex, with log(β10) = 1.56 ± 0.03. In the case of Th(IV), five different complex species could be determined: log(β10) = 4.73 ± 0.16, log(β20) = 8.92 ± 0.09, log(β30) = 12.16 ± 0.11, log(β40) = 12.96 ± 0.87, and log(β50) = 14.39 ± 0.16. The actinides were selected with regard to their most stable oxidation state in aqueous solution so that four different oxidation states from +III to +VI could be investigated. A great benefit of CE-ICP-MS is the opportunity to measure at significantly lower concentrations compared to the available literature, allowing the study of actinide complexation in environmentally relevant concentration ranges. Furthermore, it is possible to analyze all four actinides simultaneously in one and the same sample.

Ion-imprinted magnetic nanoparticles for specific separation and concentration of ultra-trace methyl mercury from aqueous sample

For rapidly and sensitively determining ultra-trace methyl mercury (MeHg) in aqueous environment, we herein synthesized a MeHg ion-imprinted magnetic nanoparticle (MeHg IIMN) to simply and specifically extract/concentrate ultra-trace MeHg from water samples. The MeHg IIMN employed core-shell Fe3O4@SiO2 nanoparticles (Fe3O4@SiO2 NPs) as supporting structure, the complex ion of 1-pyrrolidinecarbodithioic acid and MeHg (PDC-CH3Hg+) as template, methacrylic acid (MAA) as functional monomer and trimethylolpropane trimethacrylate (TMPTM) as cross linker. The MeHg IIMN offered obvious advantages such as low cost, easy manipulation, better specificity and stability, and recycling characteristics. It can be used to separate/concentrate ultra-trace MeHg from natural water sample within 30min with a recovery >95%, an enrichment factor of 250, a relative standard deviation (RSD, n=5) <7%, a 25mg MeHg/g of maximum adsorption capacity, 50 times of recycling, and without obvious interference of other ions. Combining with capillary electrophoresis-inductively coupled plasma mass spectrometry (CE-ICP-MS), it can be used for the accurate detection of ultra-trace methyl mercury in natural water samples with a limit of detection of 0.084pg/mL, a recovery of 92–99% and a RSD (n=5)<8%. The success of this study promises a valuable technique for relatively simple detection of ultra-trace methyl mercury in aqueous environment.

Determination of Lead Species in Algae by Capillary Electrophoresis-Inductively Coupled Plasma-Mass Spectrometry

A method of capillary electrophoresis (CE) coupled with inductively coupled plasma-mass spectrometry (ICP-MS) was established to determine lead ion [Pb(II)], trimethyl lead (TML), and triethyl lead (TEL). An extraction technology for lead with different species in algae was proposed and optimized for qualitative and quantitative analyses. Experimental results showed that these three lead compounds could be effectively separated within 20 min by CE-ICP-MS in a buffer solution of 70 mM H3BO3 and 17.5 M Na2B4O7 (pH 8.9). This method had good reproducibility for migration time (relative standard deviation (RSD) < 4%) and peak area (RSD < 5%). On the basis of this, the three lead compounds were detected in the linearity range of 10–200 μg L−1 with the correlation coefficient over 0.90. The detection limits for Pb(II), TML and TEL (S/N = 3, Pb) were 0.091, 0.023 and 0.030 μg L−1, respectively. The fractional extraction rate of Pb exceeded 80%, and the recoveries of Pb(II), TML, and TEL in algae samples were 103.6%, 95.7% and 90.6%, respectively. The detection results of lead content in laver and kelp samples showed that Pb in algae mainly existed in the form of Pb(II). Given its simplicity, high efficiency, and low sample consumption, the method could provide technical support for the quality control of marine algae and other marine products.

Ultra-sensitive speciation analysis of mercury by CE-ICP-MS together with field-amplified sample stacking injection and dispersive solid-phase extraction.

A simple dispersive solid-phase extraction (DSPE) used to extract and preconcentrate ultra-trace MeHg, EtHg and Hg(2+) from water sample, and a sensitive method for the simultaneous analysis of MeHg, EtHg and Hg(2+) by using capillary electrophoresis-inductively coupled plasma mass spectrometry (CE-ICP-MS) with field-amplified sample stacking injection (FASI) were first reported in this study. The DSPE used thiol cotton particles as adsorbent, and is simple and effective. It can be used to extract and preconcentrate ultra-trace mercury compounds in water samples within 30 min with a satisfied recovery and no mercury species alteration during the process. The FASI enhanced the sensitivity of CE-ICP-MS with 25-fold, 29-fold and 27-fold for MeHg, EtHg and Hg(2+) , respectively. Using FASI-CE-ICP-MS together with DSPE, we have successfully determined ultra-trace MeHg, EtHg and Hg(2+) in tap water with a limits of quantification (LOQs) of 0.26-0.45 pg/mL, an RSD (n = 3) < 6% and a recovery of 92-108%. Ultra-high sensitivity, as well as much less sample and reagent consumption and low operating cost, make our method a valuable technique to the speciation analysis of ultra-trace mercury.

Determination of arsenic speciation in Scomberomorus niphonius by capillary electrophoresis-inductively coupled plasma mass spectrometry

A method for the detection of arsenocholine (AsC), arsenobetaine (AsB), As(III), dimethylarsinic (DMA), monomethylarsonic (MMA) and As (V) by capillary electrophoresis-inductively coupled plasma mass spectrometry (CE-ICP-MS) was established. The results showed that the six species of arsenic were separated within 20 min under the optimized conditions. Good linearities of 6 arsenic species were observed in the range from 2 to 50 μg x L(-1) with the linear correlation greater than 0.996, the detection limits were 0.10-1.08 μg x L(-1) and the RSDs (n = 5) of the peak areas were smaller than 7%. The method was successfully adopted to the determination of the species in Scomberomorus niphonius. The recoveries were between 93% and 98%, and we found the arsenobetaine (AsB) was the main species in the sample. The method was suitable for the analysis of other biological samples with the advantages of good stability, less sample consumption, short analysis time and convenience.

Speciation Analysis of Arsenic in Groundwater by Capillary Electrophoresis-Inductively Coupled Plasma Mass Spectrometry

A method for the detection of trace As(Ⅲ),As(Ⅴ),monomethylarsonic acid( MMA),dimethylarsinic acid( DMA) in groundwater by capillary electrophoresis-inductively coupled plasma mass spectrometry( CE-ICP-MS) was developed. The results showed that the above four species of arsenic were baseline separated within 9 min under the optimized conditions. The detection limits( S / N = 3) of As(Ⅲ),As(Ⅴ),DMA,MMA were 0. 2-0. 5 μg / L,and the RSD( n = 6) of the peak areas were smaller than 4. 0%. The recoveries were 93%-106%. The result indicated that As(Ⅲ) and As(Ⅴ) as the main arsenic speciation existed in the groundwater of Inner Mongolia.

Speciation analysis of arsenic in seaweeds by capillary electrophoresis-inductively coupled plasma mass spectrometry

A method for the detection of trace As (III), As (V), monomethylarsonic acid (MMA), dimethylarsinic acid (DMA), arsenocholine (AsC) and arsenobetaine (AsB) in seaweeds by capillary electrophoresis-inductively coupled plasma mass spectrometry (CE-ICP-MS) was developed. The optimized conditions of CE including chemical component, pH and concentration of the buffer, separation voltage and injection time were studied in detail. The results showed that the above six species of arsenic were baseline separated within 25 min under the optimized conditions. The relative standard deviations (n = 6) of the peak areas were smaller than 5%, and the detection limits (calculated as As) (S/N = 3) were 0.08 - 0.12 microg/L for all the above six species of arsenic. The method has been successfully applied to the determination of the species of arsenic in kelp samples. The recoveries were 90% - 103%. The method has good reproducibility, high sensitivity, short analytical time and strong resistance to complex matrix, and can be used for the speciation analysis of arsenic in real seafood samples.

Determination of the stability constants of nitrate complexes of Np(V) and Pu(V) using CE-ICP-MS

The interactions of pentavalent Np and Pu with nitrate ligands has been investigated in perchlorate/ nitrate media by capillary electrophoresis-inductively coupled plasma mass spectrometry (CE-ICP-MS). The binding constant for the complex PuO 2 NO 3 , logl 10 β° PuO2NO3 =0.14 ± 0.14, is established for the first time while a new value for NpO 2 NO 3 , log 10 β° NpO2NO3 = 0.13 ± 0.14, is proposed. The usual analogy applied between Np(V) and Pu(V) interactions seems to be valid for nitrates.

Trace Metal Speciation by Capillary Electrophoresis Hyphenated to Inductively Coupled Plasma Mass Spectrometry: Sulfate and Chloride Complexes of Np(V) and Pu(V)

In the framework of nuclear waste disposal, it is very important to well understand the behavior of actinides in the presence of the common environmental inorganic ligands such as sulfate and chloride. In this work, the AnO2SO4(-) and AnO2Cl 1-1 complexes have been evidenced by capillary electrophoresis-inductively coupled plasma mass spectrometry (CE-ICPMS) in perchlorate/chloride and in perchlorate/sulfate media for An = Np and Pu. Their binding constants have been measured: log beta(PuO2SO4(-))(0) = 1.30 +/- 0.11, log beta(PuO2Cl)(1 M NaCl) = -(0.40 +/- 0.07), log beta(NpO2SO4(-))(0) = 1.34 +/- 0.12, and log beta(NpO2Cl)(1 M NaCl) = -(0.40 +/- 0.07). These results are consistent with published values for Np(V). They confirm the expected analogy between Np(V) and Pu(V) for the weak bonding with chloride ligand, log10 beta(PuO2Cl) approximately = log10 beta(NpO2Cl), attributed to mainly electrostatic interactions. Conversely, a slight shift is observed for the bonding with sulfate ligand, log10 beta(NpO2SO4(-)) > log10 beta(PuO2SO4(-)), indicating that some covalency might stabilize the sulfate complexes.

Determination of fission products in nuclear samples by capillary electrophoresis-inductively coupled plasma mass spectrometry (CE-ICP-MS)

Determination of fission products and of their isotopic composition is of high importance for the characterisation and complete inventory of nuclear fuels. Radiometric and mass spectrometric methods, which are currently used, enable only an incomplete determination of the fission products. Radiometric methods cannot be applied to all fission products and mass spectrometric methods are hindered by the existence of isobaric interferences, therefore a previous chemical separation is required before mass spectrometric analysis. Capillary electrophoresis (CE) has been coupled with inductively coupled plasma mass spectrometry (both ICP-QMS and ICP-SFMS). Typical detection limits of 6 ng/mL and 4 pg/mL for caesium as well as 8 ng/mL and 7 pg/mL for lanthanides have been obtained by CE-ICP-QMS and CE-ICP-SFMS, respectively. In addition to these very low detection limits, the procedures present the advantages to be fast (6 min for caesium and 13 min for lanthanides, respectively), to require a low microliter range sample volume and a nanoliter range injection volume. The radiation dose for the personnel as well as the volume of nuclear liquid wastes generated during the measurements are consequently reduced. The procedures have been applied to nuclear samples from PUREX process and leachates from MOX fuels.

Lanthanide–humic substances complexation. I. Experimental evidence for a lanthanide contraction effect

The interaction of the lanthanides (Ln) with humic substances (HS) was investigated with a novel chemical speciation tool, Capillary Electrophoresis-Inductively Coupled Plasma Mass Spectrometry (CE-ICP-MS). By using an EDTA–ligand competition method, a bi-modal species distribution of LnEDTA and LnHS is attained, separated by CE, and detected online by sector field ICP-MS. We quantified the binding of all 14 rare earth elements (REEs), Sc and Y with Suwannee river fulvic acid, Leonardite coal humic acid, and Elliot soil humic acid under environmental conditions (pH 6–9, 0.001–0.1 mol L −1 NaNO 3, 1–1000 nmol L −1 Ln, 10–20 mg L −1 HS). Conditional binding constants for REE–HS interaction ( K c) ranged from 8.9 < log K c < 16.5 under all experimental conditions, and display a lanthanide contraction effect, Δ L K c: a gradual increase in K c from La to Lu by 2–3 orders of magnitude as a function of decreasing ionic radius. HS polyelectrolyte effects cause K c to increase with increasing pH and decreasing ionic strength. Δ L K c increases significantly with increasing pH, and likely with decreasing ionic strength. Based on a strong correlation between Δ L K c values and denticity for organic acids, we suggest that HS form a range of tri- to tetra-dentate complexes under environmental conditions. These results confirm HS to be a strong complexing agent for Ln, and show rigorous experimental evidence for potential REE fractionation by HS complexation.

Roxarsone and transformation products in chicken manure: Determination by capillary electrophoresis‐inductively coupled plasma‐mass spectrometry

The determination of the animal feed additive roxarsone (3-nitro-4-hydroxyphenylarsonic acid) and six of its possible transformation products (arsenite, arsenate, monomethylarsonate, dimethylarsinate, 3-amino-4-hydroxyphenylarsonic acid, and 4-hydroxyphenylarsonic acid) in chicken manure was investigated using capillary electrophoresis-inductively coupled plasma-mass spectrometry (CE-ICP-MS). Initial method development was conducted using ultraviolet (UV) detection for ruggedness and time efficiency. Separation of these seven arsenic species was effected using a 20 mM phosphate buffer at pH 5.7. The CE-ICP-MS limits of detection in terms of As for each of the species was in the low microg.L(-1) range, corresponding to absolute detection limits in the range 20-70 fg As (based on a 23 nL injection). Overall, the method developed in this study provides high selectivity and low limits of detection (1-3 microg.L(-1) or low-ppb, based on As), uses small sample volume (low nL), and produces minimal wastes.

Determination of neodymium–fulvic acid binding constants by capillary electrophoresis inductively coupled plasma mass spectrometry (CE-ICP-MS)

Capillary electrophoresis inductively coupled plasma mass spectrometry (CE-ICP-MS) has been used to study neodymium–Suwannee river fulvic acid (FA) interaction at pH 6–9 and 0.001–0.1 mol L−1 ionic strength. The use of a strong ligand (EDTA) competition method allowed us to succesfully manipulate a bimodal species distribution of NdFA and NdEDTA. These two species have sufficiently different charge and shape characteristics to be easily separable by CE, even in the presence of nebulizer induced siphoning. The NdFA and NdEDTA complexes were found to be stable on the timescale of a CE separation and quantitative artifacts due to complex dissociation were therefore negligible. A method development scheme for quantitative CE-ICP-MS addresses metal–ligand dissociation specifically and is oulined in this study. Siphoning induced laminar flow was optimized and used to our advantage by speeding up separations. Log values of conditional binding constants for Nd–FA complexation at 0.1 mol L−1 ionic strength varied gradually from 9.1 to 12.5 over the pH range 6–9. Detection limits for Nd speciation were 500 pM.

Disequilibrium effects in metal speciation by capillary electrophoresis inductively coupled plasma mass spectrometry (CE-ICP-MS); theory, simulations and experimentsElectronic supplementary information (ESI) available: Computer simulations of Sm-Cit (Animation 1, corresponding with Fig. 3), Sm-HA (Animation 2, corresponding with Fig. 4) and Sm-HA-EDTA (Animation 3) separations. See http://www.rsc.org/suppdata/an/b4/b407162j/.

A theoretical-experimental approach to evaluate disequilibrium effects in capillary electrophoresis inductively coupled plasma mass spectrometry (CE-ICP-MS) is presented. Electrophoresis requires metal ligand (ML) complexes to be stable on the time scale of separation and detection. By expressing ML complex stability in terms of half-life during a CE separation, an evaluation of separation artifacts can be made. Kinetically slow metals like Cr, Al or Fe form complexes that are stable on the time scale of electrophoretic separations. Kinetically fast metals, like Pb, Hg, Cu, Cd and REE, however tend to form labile complexes which unless complexed by strong chelators will dissociate during CE separations. A reactive transport simulation model of CE separations involving ML complexes allows a more detailed prediction of disequilibrium bias and identifies kinetically limited from mobility-limited types of dissociation. Complementary experimental results are given for kinetic and equilibrium binding experiments of Sm with humic acid. The equilibrium logK for Sm-Leonardite humic acid (HA) binding at pH 7 and 0.01 mol L(-1) ionic strength was determined to be 13.04. Kinetic rates of formation and dissociation for SmHA were 5.9 10(8) and 5.3 10(-5) mol s(-1).

Dispersion effects of laminar flow and spray chamber volume in capillary electrophoresis–inductively coupled plasma-mass spectrometry: a numerical and experimental approach

Band broadening related to laminar flow and spray chamber dead volume is a potential problem in flow injection (FI)–inductively coupled plasma-mass spectrometry (ICP-MS). We studied these two dispersion effects with a sheath flow capillary electrophoresis (CE)–ICP-MS interface. A numerical model was used to simulate advection diffusion processes in the CE-capillary and dispersion in the spray chamber. Experimental results of FI with this CE–ICP-MS interface agree well with numerical modeling results. Dispersion due to laminar flow depends strongly on capillary diameter and analyte diffusion coefficient and to a lesser extent on laminar velocity and capillary length and typically amounts to one order of magnitude peak width increase. Three spray chambers of 5, 20 and 150 ml dead volume showed an increase in band broadening and peak tailing with increasing dead volume. The use of standard Scott-type spray chambers (>90 ml volume) increases peak widths by 5–10 s regardless of injection time. The use of a low dead volume spray chamber is recommended for experiments where resolution is critical. The modeling approach can be extended to the coupling of other flow injection techniques, like micro-LC and nano-LC with ICP-MS.

Determination of monophosphate nucleotides by capillary electrophoresis inductively coupled plasma mass spectrometry.

A preliminary study of a modified microconcentric nebulizer (CEI-100, CETAC) as the sample introduction device of capillary electrophoresis inductively coupled plasma mass spectrometry (CE-ICP-MS) for the determination of monophosphate nucleotides is described. The monophosphate nucleotides studied include adenosine 5'-monophosphate (AMP), guanosine 5'-monophosphate (GMP), uridine 5'-monophosphate (UMP) and inosine 5'-monophosphate (IMP). The species studied were well separated using a 70 cm length x 75 microm id fused silica capillary while the applied voltage was set at -22 kV and a 20 mmol l(-1) ammonium citrate/citric acid buffer (pH 4.0) containing 0.1% m/v cationic polymer (hexadimethrine bromide, Polybrene) was used as the electrophoretic buffer. The electroosmotic flow was reversed by flushing the fused silica capillary with 0.2% m/v Polybrene to accelerate separation. The detection limit of various species studied was in the range of 0.036-0.054 microg P ml(-1), which corresponded to the absolute detection limit of 1.1-1.6 pg P based on the injection volume of 30 nl. We determined the concentrations of nucleotides in two IG-enriched monosodium glutamates purchased from the local market. The recovery was in the range of 100-112% for various species, and the concentrations of IMP and GMP in these samples were in the range of 0.15-0.18% m/m.

Determination of cobalamins using capillary electrophoresis inductively coupled plasma mass spectrometry

The determination of cobalamins using capillary electrophoresis inductively coupled plasma mass spectrometry (CE-ICP-MS) was investigated. Both capillary zone electrophoresis (CZE) and micellar electrokinetic chromatography (MEKC) modes of operation were studied. The optimal separation of four cobalamin species (cyanocobalamin, hydroxocobalamin, methylcobalamin, and 5′-deoxyadenosylcobalamin) and a potentially harmful corrinoid analogue (cobinamide dicyanide) was obtained using CZE at a pH of 2.5. Both 20 mM phosphate and 20 mM formate buffers were used with success, although the formate buffer provided improved resolution. The CZE-ICP-MS method was used to quantify cyanocobalamin in a vitamin supplement and the analytical results were in good agreement (±5%) with values obtained by ICP-MS for total Co levels. The solution detection limits for cobalamins using CZE-ICP-MS were approximately 50 ng/ml. MEKC was found to be useful for the screening of vitamin preparations because it provided a rapid means of distinguishing cyanocobalamin (the form most commonly used in vitamin preparations) from free cobalt. The separation of free cobalt and cyanocobalamin using MEKC was achieved in less than 10 min.