Environmental Sample Preparation Using the Microlab 600 Is Accurate and Fast

Environmental laboratories analyze customer samples to determine the concentration of contaminants in soil, drinking water, and so on. Frequently these samples are diluted prior to analysis by the ICP-MS. It is critical that these dilutions are accurate and reproducible. In this study we compared the speed, accuracy, and consumable costs for common sample preparation techniques and found that the Microlab 600 is the best option.

Pipettes, volumetric glassware, syringes, and the Microlab 600 Diluter are commonly used to dilute environmental samples. Each of these techniques offers different advantages and disadvantages. Volumetric glassware is easy to use but dilution waste volumes are large and the glassware requires cleaning. Pipettes have small dilution volumes but the accuracy varies across different solvents. Additionally, the consumable plastic tip increases cost per sample and for some applications can leach contaminants. Syringes produce small dilution volumes and are inert, but manual operation and cleaning reduces throughput. The Microlab 600 has small dilution volumes, an inert fluid path, and is the fastest of the techniques.

Experimental Conditions

Each technique (volumetric glassware, pipettes, syringes, and the Microlab 600) was used to prepare dilutions of a standard stock solution. The samples were diluted to 1:1, 1:4, 1:9, 1:49, 1:99, and 1:199 in replicates of five. Each technique was performed one at a time. The samples were then analyzed and the data plotted to compare the accuracy of the different techniques.

Results

The results shown in Figure 1 show the dilution series for each technique along with a best fit line and an R² value. All techniques showed a high correlation but the Microlab 600 was the highest with a value of 0.9992.

Conclusions

Each of the techniques yielded accurate dilutions with an aqueous stock solution. Of the four options tested the Microlab 600 consumed the least amount of sample and diluent, required no consumable pipette tips, and had an inert fluid path making it compatible with all tests performed in an environmental lab.

Additional head to head testing was performed between pipettes and the Microlab 600 using live samples at a local environmental lab. This testing showed that the Microlab 600 achieved a 40% reduction in processing time making it the clear choice for environmental sample preparation.

Hamilton Company

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