Elemental Scientific. Automated Speciation. prepfast-ic Chromium Speciation for Toy Materials (EN 71-3) ICP ICPMS AA

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1 prepfast-ic Automated Speciation prepfast-ic Chromium Speciation for Toy Materials (EN 71-3) Presented at the 015 European Winter Plasma Conference Authors: Aurelien Viscardi, Kyle Uhlmeyer & Patrick Sullivan Elemental Scientific ICP ICPMS AA

2 Specific Autocalibration Abstract The new regulation (EN 71-3 and 71-3A1) concerning toy safety requires the detection of Cr VI at very low levels, possibly in the presence of a large excess of Cr III. In this new regulation the maximum allowed value in Category II toys for Cr VI is 5µg/Kg. This means that after sample preparation and extraction with 0,07M HCl for hours, the measured concentration of Cr VI must be less than 10ng/L. The typical method used to separate Cr III from Cr VI is HPLC-ICP-MS, however detection of such low levels can be a challenge for this technique. The principal issues are column capacity, potential contamination in the sample preparation steps, and the ArC + interference on 5 Cr +. In this paper we examine the advantages of low pressure ion exchange chromatography coupled to an ICPMS fitted with a universal cell (collision/reaction) to perform low level Cr speciation. The analysis is fully automated by using a syringe-driven inline dilution system to automatically calibrate the ICPMS for both Cr III and Cr VI. To validate the method real samples have been measured and spiked to the lowest level required by the new regulations. Features Autocalibrate Species Specific Standards Mixed Standards Autodilute Samples Autocalibrate from Stock at Time of Use Combined with Elemental Analysis

3 Species Specific Autocalibration 10 Cr (III) 4 9 Cr(VI) (100ppt) ppt Mix 7 BLANK STD Position 1 Inline Dilution Factor 00x 0x 10x 6.6x 5x 4x x Flow Rate (µl/min) Std Diluent Total Concentration (100ppt) prepfast Calibration: Blank can be analyzed diluted or undiluted Figure 1. Autocalibration allows users to generate several calibration curves with multiple points at any frequency with ease. This minimizes effects of species conversion after standard preparation. Cr (VI) Autocalibration R = ppt 5ppt 10ppt 15ppt 0ppt 5ppt Figure. Inline preparation of low level standards from concentrated stock solutions eliminates environmental contamination. This provides linear calibration curves in the single digit ppt range. 3

4 Specific Separation prepfast-ic Schematic Waste NexION SmartTuner M8 % HNO 3 Dual Detector AsE1 DI Water Tune Cr Eluent AsE Strong Acid Carrier Diluent Internal Standard SC DX FAST Autosampler Vacuum Waste EN 71-3 Migration Limits from Toys Elemental Scientific Exceeds LOD Element Category I (mg/kg) Category II (mg/kg) Category III (mg/kg) Chromium (III) Chromium (VI) Element Category I (µg/l) 500x dilution Category II (µg/l) Category III (µg/l) Chromium (III) Chromium (VI) Cr (III) / Cr (VI) Max For 100 mg sample prepared in 5 ml migration solution (EN 71-3:7.4..) with additional 10x dilution at analysis (EN 71-3:F.4) (500x total dilution) 4

5 Exceeds EN 71-3 Limits Cr (VI) Limit of Detection Cr (VI) LOD = µg/L 5ppt Cr (VI) 5ppt Cr (III) Figure 3. Chromatograph illustrates 10ppt Cr (VI) EN 71-3 requirements are easily achieved. Cr (III) / Cr (VI) > 4800x Exceeds Cr(III)/Cr(VI) Cr(VI) 4800x Cr(III) Cr(III) Only Cr(VI) + Cr(III) Figure 4. A log scale chromatograph demonstrates more than sufficient resolution to determine Cr (VI) in the presence of 4800x Cr (III). The system automatically applies extra rinse times when Cr (III) levels are high to ensure complete rinse out before the next sample is analyzed. 5

6 Specific Quantification Simple Data Acquisition 1. Method Read Delay Determines Start of Cr-6 Measurement. After DRC Cell Gas Flow Delay the Cr-3 Measurement Begins prepfast-ic Separate DRC Mode for Each Species Figure 6. The NexION FAST FIAS trigger starts the acquisition of Cr (VI) and then Cr (III). 6

7 Simple Quantification Overlay of Separate Chrome Species 10 ppt Cr(VI) 10 ppb Cr(III) Figure 7. The Syngistix software is able to measure Cr(VI) and Cr(III) separately. Bubble Solution As Analyzed (ng/l) In Solid (mg/kg) Recovery of.5 µg/kg Cr (VI) Spike (5ppt spike) 1 < 5 < % < 5 < % 3 < 5 < % 4 < 5 < % 5 < 5 < % Five different bubble solutions were prepared following EN 71-3 procedures. Cr (VI) was below the limit of detection and.5 µg/kg spikes were quantitatively recovered. 7

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