Metrohm inline sample preparation (MISP) is a versatile collection of cost and time-effective techniques that reduce manual sample preparation. This article discusses a combination of inline dilution and subsequent inline ultrafiltration which allows automatic dilution and subsequent filtration of samples before injection.
MagIC Net allows intelligent dilution to be run by checking results and the sample to be re-diluted if the result is not within the calibration range. In addition, the stock standard solution is automatically diluted for multipoint calibration. As a result, each analyte can be automatically calibrated effectively.
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Sample
Mixed standard stock solution (1000 mg/L of each anion)
Sample preparation
Metrohm inline dilution technique (MIDT) followed by Metrohm inline ultrafiltration.
Columns
| . |
. |
| Metrosep A Supp 5 - 100/4.0 |
6.1006.510 |
| Metrosep A Supp 5 Guard/4.0 |
6.1006.500 |
Solutions
| Eluent |
3.2 mmol/L sodium carbonate
1.0 mmol/L sodium hydrogen carbonate |
| Suppressor regenerant |
100 mmol/L sulfuric acid |
| Rinsing solution |
STREAM |
Analysis
Conductivity detection following the sequential suppression.
Instrumentation
| 930 Compact IC Flex Oven/SeS/PP/Deg |
2.930.2560 |
| IC Conductivity Detector |
2.850.9010 |
| 858 Professional Sample Processor |
2.858.0020 |
| 800 Dosino |
2.800.0010 |
| 741 Magnetic Stirrer |
2.741.0010 |
| IC equipment: Inline Dilution |
6.5330.120 |
| IC equipment: Inline Ultrafiltration |
6.5330.130 |
| MSM Rotor A |
6.2832.000 |
| Adapter sleeve for Suppressor Vario |
6.2842.020 |
Parameters
| . |
. |
| Flow rate |
0.7 mL/minutes |
| Injection volume |
20 μL |
| Pmax |
15 MPa |
| Recording time |
11.5 minutes |
| Column temperature |
45 °C |
| Final dilution volume |
7 mL |
Calibration
| . |
| Stock standard solution |
50.0 mg/L of chloride, nitrate, and sulfate each |
| Dilution factor |
Calibration level |
| Calibration level |
Dilution factor |
Concentration |
| Level 1 |
1 |
50.0 mg/L |
| Level 2 |
2 |
25.0 mg/L |
| Level 5 |
5 |
10.0 mg/L |
| Level 10 |
10 |
5.00 mg/L |
| Level 20 |
20 |
2.50 mg/L |
| Level 50 |
50 |
1.00 mg/L |
Setup Scheme
The installation is carried out in accordance with the AB 376 ProfIC Vario 6 Anion.
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Results
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| Anion |
Calibration
RSD [%] |
Calibration
Corr. Coeff. |
Dilution 1:50
RSD [n = 10, %] |
Dilution 1:50
Recovery [%] |
| 1 |
Chloride |
1.423 |
0.99996 |
2.18 |
101.1 |
| 2 |
Nitrate |
2.128 |
0.99992 |
1.88 |
102.5 |
| 3 |
Sulfate |
1.536 |
0.99995 |
1.42 |
100.6 |
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This information has been sourced, reviewed and adapted from materials provided by Metrohm AG.
For more information on this source, please visit Metrohm AG.