Size-Based Analysis of Au NPs by Online Monolithic Capillary. Microextraction-ICPMS

Transcription

1 Supporting Information Size-Based Analysis of Au NPs by Online Monolithic Capillary Microextraction-ICPMS Xiaolan Liu, Beibei Chen, Yabing Cai, Man He, Bin Hu * Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education), Department of Chemistry, Wuhan University, Wuhan 4372, People s Republic of China Content Instrumentation and Reagents Synthesis of Au NPs Sample Preparation Figure S1-S7 Table S1-S3 * Fax: Tel: binhu@whu.edu.cn S-1

2 Instruments and Reagents An FIA-311 flow injection system (Jitian Tech. Co. Ltd., Beijing, China) was used for on-line coupling CME with ICPMS. The Au NPs were characterized by JEM-21 transmission electron microscope (HR, Japan) and ALV/SP-125 dynamic light scatter (ALV, German). γ-methacryloxypropyl trimethoxysilane (γ-maps) was purchased from Chemical Plant of Wuhan University (Wuhan, China). 4-Vinylpyridine (4-VP), dodecanol methylene bis(acrylamide) (Bis) and 2,2-azobisisobutyronitrile (AIBN) were purchased from Sigma-Aldrich (St. Louis, MO). Acrylamide (AA) and dimethyl sulfoxide (DMSO) were obtained from Sinopharm (Shanghai, China). All chemicals were of analytical grade or better. High purity deionized water (18.2MΩ cm) obtained from Milli-Q Element system (Millipore, Molsheim, France) was used throughout this work. All glassware was kept in 1% (v/v) nitric acid for at least 24 h and washed three times with high purity deionized water before use. Synthesis of Au NPs The Au NPs was prepared according to the Ref. 1 and 2. The preparation method of Au NPs with the size about 3 nm is as follows: in the room temperature,.2 ml 1% HAuCl 4 was added into 18 ml high purity water. After intensive stirring,.4 ml 1% sodium citrate solution was added. After 1 min,.2 ml.75% fresh prepared NaBH 4 (dissolved in 1% sodium citrate). Five minutes later, the prepared Au NPs was stored in the refrigerator at 4 C. The preparation method of Au NPs with the size about 1 nm, 2 nm and 3 nm is as following:.5 ml 1% HAuCl 4 was added into 49.5 ml high purity water in the flask. After violent stirring and heating to boiling, 2.5 ml, 1.5 ml and 1 ml 1% sodium citrate solution was added as reductant, respectively. Keep boiling for 15 minutes, the flask was transferred onto the magnetic stirrer and cooled to the room temperature and the prepared Au NPs was stored in the refrigerator at 4 C. The 4 nm Au NPs was a commercial one which was mentioned above. The Au NPs with the size about 3 nm, 1 nm, 2 nm, 3 nm and 4 nm were named as groups A, B, C, D and E, respectively. S-2

3 Sample Preparation To validate the applicability of the proposed method in real sample analysis, spiking experiments were also conducted by adding Au NPs with different particle size in the sample solution. Briefly, the Lake water solution was separated into two portions. One portion was spiked with 1 μg L -1 3 nm Au NPs and 2 nm Au NPs, the other portion was spiked with 1 μg L -1 1 nm Au NPs and 3 nm Au NPs, and then subjected to the same procedure described above. S-3

4 Figure S1 Characterization of Au NPs in groups A-E by TEM. S-4

5 Signal Signal Signal Signal 1..8 Au NPs of group B 1..8 Au NPs of group C Size (nm) Size (nm) B C 1..8 AuNPs of group D 1..8 Au NPs of group E Size (nm) D Figure S2 The DLS of Au NPs in groups B-E Size (nm) E S-5

6 Figure S3 Effect of eluent concentration on the recovery of Au NPs in group A (A), in group B (B), in group C (C), in group D (D) and group E (E), respectively (the concentration of Au NPs 5 μg L -1 as Au; sample volume: 1 ml; ph = 7; sample flow rate:.25 ml min -1 ; eluent: 1 μl cysteamine ph=7 each time). S-6

7 Figure S4 The comparison of recovery of citrate-au NPs and MUA-Au NPs in different groups (the concentration of eluent: 1 µl.3%, 1.5%, 2% and 15% cysteamine for groups A-D, respectively, and 2 µl 1% cysteamine for group E). S-7

8 Figure S5 Separation of Au NPs of groups (1) A and D, (2) A and E, as well as (3) B and E with the concentration ratio of 1: 1. S-8

9 2 Au NPs 3+2 nm (1:5) 3 25 Au NPs 3 nm+2 nm (5:1) (1) 3 25 Au NPs 3nm+3nm (1:5) 35 3 AuNPs 3nm+3nm (5:1) (2) 35 3 Au NPs 3nm+4nm (1:5) 6 5 AuNPs 3nm+4nm (5:1) (3) 3 25 Au NPs 1 nm+3 nm (1:5) 35 3 Au NPs 1 nm +3 nm (5:1) (4) S-9

10 4 Au NPs 1nm+4nm (1:5) 5 Au NPs 1nm+4nm (5:1) (5) Figure S6 Separation of Au NPs of groups (1) A and C, (2) A and D, (3) A and E, (4) B and D as well as (5) B and E with concentration ratio of 1: 5 and 5:1 separately. S-1

11 Ln C(Cysteamine) Recovery (%) Recovery (%) Au NPs of group B NIST RM % 1% 1.5% 2% Concentration of cysteamine.5% 1% 1.5% 2% Concentration of cysteamine A B Size of Au NPs (nm) C Figure S7 (A) Effect of eluent concentration on the recovery of Certified Reference Material (Au NPs, NIST RM 811); (B) Comparison of elution conditions for Au NPs in group B and NIST RM 811 Au NPs; (C) The NIST AuNP standard (red) was characterized using this calibration curve (the concentration of Au NPs 5 μg L -1 as Au; sample volume: 1 ml; ph = 7; sample flow rate:.25 ml min -1 ; eluent: 1 μl cysteamine ph=7 each time). S-11

12 Table S1. Operating conditions of ICPMS ICPMS plasma Rf power 125 W Plasma gas (Ar) flow rate 14 L min -1 Auxiliary gas (Ar) flow rate.88 L min -1 Carrier gas (Ar) flow rate 1.7 L min -1 Sampling depth 7. mm Sampler/skimmer diameter orifice Nickel 1. mm/.4 mm Time-resolved data acquisition Scanning mode Peak hopping Dwell time 1 ms Integration mode Peak area Points per spectral peak 1 Isotopes 197 Au S-12

13 Table S2. The quantification results of Au NPs in different groups by online CME-ICPMS Added (μg L -1 ) Found (μg L -1 ) Recovery (%) 3 nm 2 nm 3 nm 2 nm 3 nm 2 nm ±.7.9± ± ± ±15.85± Added (μg L -1 ) Found (μg L -1 ) Recovery (%) 3 nm 3 nm 3 nm 3 nm 3 nm 3 nm ±.1 1.2± ±.6 5.7± ±.35.91± Added (μg L -1 ) Found (μg L -1 ) Recovery (%) 3 nm 4 nm 3 nm 4 nm 3 nm 4 nm ±.9.97± ± ± ±.15.91± Added (μg L -1 ) Found (μg L -1 ) Recovery (%) 1 nm 3 nm 1 nm 3 nm 1 nm 3 nm ±.5.84± ± ± ±.53.85± Added (μg L -1 ) Found (μg L -1 ) Recovery (%) 1 nm 4 nm 1 nm 4 nm 1 nm 4 nm ±.3.88± ± ± ±.32.9± S-13

14 Table S3. Analytical results (mean±s.d., n=3) for Au NPs in East Lake water samples Added (μg L -1 ) Found (μg L -1 ) Recovery (%) 3 nm 2 nm 3 nm 2 nm 3 nm 2 nm N.D. N.D ±.12.91± Added (μg L -1 ) Found (μg L -1 ) Recovery (%) 1 nm 3 nm 1 nm 3 nm 1 nm 3 nm N.D. N.D ±.7.83± N.D., not detected. S-14

15 REFERENCES (1) Li, L. X. Y; Leopold, K.; Schuster, M. Chem. Commun. 212, 48, (2) Brown, K. R.; Walter, D. G.; Natan, M. J. Chem. Mater. 2, 12, S-15