Navigation Links
Speciation of Arsenic by LC-ICP-MS

Michael Leist Varian

Analytical Instruments Mulgrave, Victoria 3170, Australia E-mail: icpms@varianinc.com

Introduction

As toxicity, mobility, and bioavailability can differ greatly between the various chemical species in which an element occurs, reporting only the total concentrations can often be misleading. Arsenic is one such example where the various species differ; the inorganic trivalent form (As III) is the most toxic, followed by the inorganic pentavalent form (As V). Other common forms of arsenic include monomethyl arsenic (MMA), dimethyl arsenic (DMA) and arsenobetaine (AsB), which have signifi cantly reduced toxicities. Therefore, separation and detection of these species can greatly assist risk-based toxicity assessments.

When Liquid Chromatography (LC) is interfaced with Inductively Coupled Plasma Mass Spectrometry (ICP-MS), species elute one by one from the LC column directly to the ICP-MS for detection by elemental speciation. The coupling of LC to ICP-MS is a straight forward task; the LC column is connected to the nebulizer of the ICP-MS by a piece of PEEK tubing, and no hardware changes are required to either the LC or the ICP-MS. Coupling an LC to a Varian ICP-MS has the added advantage of offering high sensitivity, with over 80% of the analyte ions passing through the skimmer cone being transferred to the quadrupole1. The Varian ICP-MS, with its patented 90 degree ion mirror2, is the worlds fi rst ICP-MS with tunable gigahertz sensitivity.

The following experiment shows the sensitivity and detection capabilities of the high sensitivity Varian ICP-MS for element speciation.

Experimental

Instrumentation

A schematic of the overall system is shown in Figure 1.

The LC system used was a Varian ProStar 230 Tertiary Solvent Delivery Module, a Rheodyne injector with a 50 μL sample loop, and a Hamilton PRP-X100 (4.1 mm x 250 mm, 10 μm) anion exchange column.

The Varian ICP-MS was used for all arsenic measurements. ICP-MS setup was fully controlled by Varians ICP-MS Expert software, which provides one-step instrument setup, optimization and method development. Prior to connecting the ICP-MS to LC, it was tuned to high sensitivity mode automatically by using the auto optimization routine included in the software. The ICP-MS nebulizer was then connected to the LC column using a 20 cm length of PEEK tubing (0.010 I.D.). See Tables 1-3 for the ICP-MS and LC conditions used.

Reagents and samples

Deionized water (18 MΩ cm, Millipore MilliQ, Billerica, MA, USA) was used for all solution preparations (calibration solutions and mobile phase).

Calibration standards

Arsenic pentoxide and arsenic trioxide were obtained from SPEX CertiPrep (Metuchen, NJ USA). Arsenobetaine (AsB, C5H11AsO2) was obtained from Sigma Aldrich (Castle Hill, NSW Australia). Cacodylic acid (dimethylarsenic acid, DMA) and monosodium acid methane arsonate (MMA) were purchased from Chem Service (West Chester, PA USA). All calibration solutions were prepared daily.

Mobile phase LC

Ammonium carbonate (Merck, Kilsyth, Victoria, Australia) and either Suprapur ammonia solution obtained from Merck (Kilsyth, Victoria, Australia) or AR Select Plus nitric acid, (Mallinckrodt Baker, Phillipsburg, NJ, USA) were used for pH adjustments of the mobile phase. The mobile phase was prepared daily.

Reference materials

Standard Reference Material 1640, Trace Elements in Natural Water was obtained from the National Institute of Standards and Technology (Gaothersburg, MD, USA). Trace Metals in Fish (HPS CRM-TMF Lot #123921), Trace Metals in Drinking Water (HPS CRM-TMDW Lot#222518) and Oyster Tissue (HPS CRM-OT Lot #209510) were all obtained from High-Purity Standards (Charleston, SC, USA). The urine reference material (Seronorm Lot#No2525) was obtained from Sero As, (Billingstad, Norway).

Results and Discussions

The time resolved data from Varian ICP-MS Expert was exported as a .CDF fi le and opened in the Galaxie software, where program data analysis was performed. For reviewing acquired data, Galaxie provides an easy way to view single or multiple chromatograms, and compare results in a single screen.

Elemental speciation

Speciation of the fi ve inorganic and organic arsenic species can be performed using either an isocratic or gradient LC method (see Figures 2 and 3). Using either method, excellent calibrations for each of the arsenic species were obtained with calibration coeffi cients ≥ 0.999 achieved when calibrating on solutions ranging from 0.01 to 50 μg/L. An example calibration curve for MMA is shown in Figure 4. Note the low calibration solution in this calibration is 0.01 μg/L (10 ng/L).

While the gradient method increases the analysis time by approximately 9 minutes (4 minutes increased analysis time and 5 minutes column re-equilibration), it does provide better separation of As(III) from DMA, and improved separation from potential interferences. For example, samples with a high Cl content can result in an additional peak (75ArCl). As shown in Figure 5, the gradient method adequately separates the Cl peak from the neighbouring MMA and AsV peaks.

Typical detection limits

Table 4 shows the typical detection limits (DLs) for the fi ve common organic and inorganic forms of arsenic. All the measurements were made under routine analytical laboratory conditions, not clean-room conditions. This work indicates typical DL values that can be routinely achieved outside a clean-room in a clean laboratory.

Although previous experiments have reported signal improvements when 13% methanol is aded to the mobile phase4, this application note demonstrates that the Varian ICP-MS can produce low detection limits without this step. The addition of methanol can also cause problems if other elements such as Cr (VI) are measured, as the formation of 40Ar13C leads to substantial degradation of the signal-to-noise ratio, and higher limits of detection. Additions above 1% methanol can also cause problems, as the chromatographic separation between AsB and As(III) may be degraded to such an extent that base line resolution is not achievable.

Analysis of reference materials

Given the lack of reference materials that are certifi ed for all fi ve arsenic species, a number of reference materials were spiked with known quantities of each species and the % recovery recorded, to test for robustness of the Gradient method.

The reference materials analyzed included two water reference materials, NIST 1640 and HPS TMDW, two biological tissue reference materials, HPS OT and HPS TMF, and a urine reference material. Each reference material was spiked with 11 μg/L of each As compound and analyzed. The HPS TMF and the Seronorm urine reference material were diluted by a factor of 100 prior to injection. The percentage spike recoveries for each reference material can be viewed in Table 5. Very good recoveries were achieved, especially considering that no internal standard was used.

Conclusions

This work has demonstrated that the Varian ICP-MS is an excellent detector when coupled with liquid chromatography for elemental speciation. Low ng/L detection limits can be routinely obtained and very good recoveries were obtained on a variety of spiked reference materials.

References

1. S. Elliott, M. Knowles and I., Kalinitchenko, A New Direction in ICP-MS, Spectroscopy , 19(1), 30 (2004)

2. I. Kalinitchenko, Ion Optical System for a Mass Spectrometer , Australian Patent 750860, 14 November 2002, US Patent 6,614,021B1, 2 September 2003.

3. K. Ackley, C. BHymer, K. Sutton, J. Caruso, Speciation of Arsenic in Fish Tissue Using Mircowave-Assited Extraction Followed by HPLC-ICP-MS, Journal of Analytical Atomic Spectrometry , 14, 845 (1999)

4. Y. Martinez-Bravo, A.F. Roig-Navarro, F.J. Lopez, F. Hernandez, Multielemental Determination of Arsenic, Selenium and Chromium(VI) Species in Water by High-Performance Liquid Chromatography Inductively Coupled Plasma Mass Spectrometry, Journal of Chromatography A , 926, 265 (2001).


'"/>

Source:


Page: All 1 2 3 4 5

Related biology technology :

1. A Positive Selection Assay for Mutation Analysis in Big Blue Animals
2. Epitope-Tagging Vectors for Functional Analysis in Yeast
3. Map and Link Human Genetic Disorders with SSLP Analysis
4. CastAway Precast Gels for Rapid Automated DNA Sequence Analysis
5. Single-cell RT-PCR Analysis of Paramecium Primaurelia with the Eppendorf cMaster RTplusPCR System
6. Structural Analysis of Glycosylated Peptides in Complex Mixtures with Ion Trap MSn
7. Use of Transcriptor Reverse Transcriptase in Microarray Analysis
8. Increased Sensitivity in Microarray Analysis
9. Gene-Expression Analysis of TP, DPD, and TS Using the LightCycler mRNA Quantification KitsPLUS
10. Agilent 2100 Bioanalyzer Automated Analysis System
11. Analysis of Microarray Data
Post Your Comments:
*Name:
*Comment:
*Email:
TAG: Speciation Arsenic ICP

(Date:11/21/2014)... SAN DIEGO , Nov. 20, 2014 /PRNewswire/ ... patient has been dosed in its Phase 1 ... and cisplatin for the treatment of malignant pleural ...  Polaris Group is conducting clinical trials on ADI-PEG ... other agents, for the treatment of several other ...
(Date:11/21/2014)... /PRNewswire/ - BIOREM Inc. (TSXV: BRM) ("Biorem" or "the Company") today announced ... 30, 2014.  Biorem,s complete 2014 third quarter financial statements and MD&A ... Summary:Three-months ended September 30, , Nine-months ended ... 2014 , 2013 , 2014 ... , 6,715 , 14,476 Gross profit , ...
(Date:11/18/2014)... November 17, 2014 Cirrascale ... architecture blade-based and rackmount computing infrastructure, today announced ... dual-GPU accelerator throughout its GPU-enabled blade server and ... the company’s latest proprietary 80-lane Gen3 PCIe switch-enabled ... NVIDIA Tesla K80 dual-GPU accelerator cards in a ...
(Date:11/18/2014)... November 18, 2014 Alanda Software, ... Transparency Reporting solutions, announced today that a top ... its Consummate Provider™ solution in both the U.S. ... Global, SaaS based, Data Quality remediation portal, designed ... third party Providers improve their ability to capture, ...
Breaking Biology Technology:Polaris Group Announces Treatment of First Patient in Phase 1 Study of ADI-PEG 20 plus Pemetrexed and Cisplatin in Malignant Pleural Mesothelioma And Non-Squamous Non-Small Cell Lung Carcinoma 2Biorem Reports Third Quarter Results 2Biorem Reports Third Quarter Results 3Cirrascale® Expands Multi-GPU Peering Solutions with Support for New NVIDIA Tesla K80 Dual-GPU Accelerators 2Cirrascale® Expands Multi-GPU Peering Solutions with Support for New NVIDIA Tesla K80 Dual-GPU Accelerators 3Alanda Software Completes Successful Implementation of Global Data Quality & Vendor Management Solution for Top Tier Global Biopharmaceutical Company 2
... Chromatography and Mass Spectrometry Application Report , ... Equine serum Acepromazine , Gargi Choudhary, ... Wayne Skinner and Scott Stanley, University of California, ... Acepromazine is widely used as a sedative in ...
... Application Note , Kevin J. McHale, ... Thermo Electron Corporation, Somerset, NJ, USA , ... Acrylamide has been identified as a potential human carcinogen. ... but acrylamide was recently discovered to be present at significant levels in ...
... James Batchelor, and Ed Alderman , Applied ... Kelly M. Clark, Joseph A. Hensley and Robert P. Weisbein ... , Jennifer L. Halcome and George R. Halley ... CO , Introduction , ...
Cached Biology Technology:Determination of Acepromazine and its Major Metabolite in Equine Serum by LC-MS/MS using the Finnigan LCQ Deca XP Plus Ion Trap Mass Spectrometer 2Determination of Acepromazine and its Major Metabolite in Equine Serum by LC-MS/MS using the Finnigan LCQ Deca XP Plus Ion Trap Mass Spectrometer 3Determination of Acepromazine and its Major Metabolite in Equine Serum by LC-MS/MS using the Finnigan LCQ Deca XP Plus Ion Trap Mass Spectrometer 4Quantitation of Acrylamide in Food Samples on the Finnigan TSQ Quantum Discovery by LC/APCI-MS/MS 2Quantitation of Acrylamide in Food Samples on the Finnigan TSQ Quantum Discovery by LC/APCI-MS/MS 3Quantitation of Acrylamide in Food Samples on the Finnigan TSQ Quantum Discovery by LC/APCI-MS/MS 4Quantitation of Acrylamide in Food Samples on the Finnigan TSQ Quantum Discovery by LC/APCI-MS/MS 5Quantitation of Acrylamide in Food Samples on the Finnigan TSQ Quantum Discovery by LC/APCI-MS/MS 6Automation of the Eppendorf Perfectprep BAC 96 DNA Kit on the Caliper Life Sciences Sciclone ALH 3000 2Automation of the Eppendorf Perfectprep BAC 96 DNA Kit on the Caliper Life Sciences Sciclone ALH 3000 3Automation of the Eppendorf Perfectprep BAC 96 DNA Kit on the Caliper Life Sciences Sciclone ALH 3000 4
(Date:11/5/2014)... Kelly Redmond has dedicated his career to understanding ... a general audience. , As deputy director and ... at Nevada,s Desert Research Institute, Redmond has more ... application and dissemination of climate data to the ... Meeting in San Francisco on December 15-19, 2014 ...
(Date:11/4/2014)... of Utah engineers developed the first room-temperature fuel cell ... without needing to ignite the fuel. These new fuel ... power and sensors. , A study of the new ... journal ACS Catalysis . , Fuel cells convert ... fuel and an oxygen-rich source such as air. If ...
(Date:11/4/2014)... Medicine announced today that it is a Grand ... Bill & Melinda Gates Foundation. Laura Goetzl, ... Sciences; and Vice Chair of Research and Academic ... pursue an innovative global health and development research ... Neurodevelopment.", Grand Challenges Explorations (GCE) funds individuals worldwide ...
Breaking Biology News(10 mins):Nevada climatologist to be honored at AGU Fall Meeting for lifetime of public outreach 2Jet-fueled electricity at room temperature 2Temple University School of Medicine receives Grand Challenges Explorations grant 2
... - At a glance, a painting by Jackson Pollock (1912󈞤) ... on a canvas. A quantitative analysis of Pollock,s streams, ... at Boston College, reveals, however, that the artist had to ... the way that he did. The finding, published in ...
... Mensenchymal stem cells (MSCs), multipotent cells identified in ... be therapeutically effective in the immunosuppression of T-cells, the ... and suppressing chronic airway inflammation in some asthma cases. ... applications, they are cultured in fetal bovine serum. , ...
... has been followed by a decline in fertility rates in ... first concerted rise in fertility rates in the developed world ... "In a new study, scientists from the Vienna Institute ... the International Institute for Applied Systems Analysis (IIASA) identify that ...
Cached Biology News:Jackson Pollock, artist and physicist? 2Jackson Pollock, artist and physicist? 3Serum-free cultures help transplanted MSCs improve efficacy 2Fertility rates affected by global economic crisis 2
Recorder, 6", 7 Day, 1 Pen, 0 to 100°C, 220V, 50/60 Hz, for 4520, Customer Installed...
... STAR3000 HISTAR detection systems provide linking ... used with species specific primary antibodies ... specimens. Visualisation is accomplished using an ... novel polymer labelling technology. Secondary antibodies ...
Taq DNA Polymerase (T. aquaticus), 250 units. For PCR and other procedures requiring DNA polymerase activity at elevated temperatures. Category: Nucleotides & Enzymes & Biochemicals, Modifying Enzyme...
... AmpliTaq DNA Polymerase is ... the PCR process, a testimony to its ... activity profile makes it ideal for PCR ... to guarantee reproducible results. ,, AmpliTaq ...
Biology Products: