> For the complete documentation index, see [llms.txt](https://knowledge.illumina.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://knowledge.illumina.com/microarray/general/microarray-general-reference_material-list/000001422.md).

# How to avoid sample sheet formatting errors when creating a GenomeStudio project

Illumina Infinium BeadChip uses 12-digit barcodes (12-digit numeric values). When working with samples sheets in Excel, these long numeric values may be automatically converted into scientific notation. If the BeadChip barcode column in the sample sheet is not reformatted as “Number” prior to saving the file, Excel convert the values into scientific notation. As a result, the barcode values saved are inaccurate and no longer match the 12-digit identifier. When a sample sheet with altered values is imported in GenomeStudio, the software is unable recognize the barcodes. This typically results to the following error message: The project can not be created. No valid samples were loaded\
**Example**: When 123456789012 is entered into the BeadChip Barcode column and the file is saved as a CSV, Excel may automatically reformat the value. By default, Excel rounds long numeric values to approximately six significant digits, changing the barcode to 123456000000 and displaying it in scientific notation as 1.23E+11. As a result, the original 12-digit barcode is not preserved in the saved file.\
To retain the full barcode values in the sample sheet, reformat the BeadChip barcode column as “Number” with zero decimal places **before** saving the file. To format the column correctly, follow the steps below in Excel:1. Highlight column.\
2\. Right-click column.\
3\. Select **Format Cells**.\
4\. Select the **Number** tab.\
5\. Select **Number** and enter **0** as the number of decimal places.\
6\. Save the file as .csv and use it to create the GenomeStudio project.

**Important:** If the sample sheet is reopened in Excel, the formatting of the BeadChip barcode column is not preserved. Instead, Excel automatically revert the values to scientific notation. If any changes are made to the sample sheet and it needs to be saved again, the BeadChip barcode column must be reformatted to “Number” with zero decimal places before saving to ensure the barcode values remain accurate.

To avoid Excel-related formatting issues, it is recommended to check the sample sheet for accuracy using a text editor, such as Notepad. The sample sheet can be edited in Notepad without any formatting issues.

For a step-by-step demonstration on properly formatting a sample sheet, refer to the support video, [How to Format Sample Sheet for GenomeStudio Genotyping Video](https://github.com/illumina-swi/illumina-knowledge/tree/master/articles/Knowledge/How-to-Format-Sample-Sheet-for-GenomeStudio-Genotyping-Video/README.md) and/or [How to Format a Sample Sheet for a GenomeStudio Methylation Project Video](https://github.com/illumina-swi/illumina-knowledge/tree/master/articles/Knowledge/How-to-Format-a-Sample-Sheet-for-a-GenomeStudio-Methylation-Project-Video/README.md).

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| *For any feedback or questions regarding this article (Illumina Knowledge Article #1422), contact Illumina Technical Support* [*techsupport@illumina.com*](mailto:techsupport@illumina.com?subject=Question%2FFeedback%20Regarding%20Illumina%20Knowledge%20Article%20#000007124%20-%20Microarray%20\&body=Dear%20Illumina%20Technical%20Support,%0D%0A%0D%0A)*.* |


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