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The Samples section includes the SampleName, Index1, Index2, Project, Lane, and ExternalID columns. When the Samples section is populated, only SampleName is required. When unpopulated, Bases2Fastq defaults to an entry that specifies one unindexed sample for each lane.


SampleNameThe name of each library in the run. Each name can include 1–64 case-sensitive alphanumeric characters, hyphens (-), and underscores (_).
Index1, Index2The Index 1 and Index 2 sequences that correspond to each library. Each sequence consists of A, C, G, and T, with a plus sign separating multiple sequences.
LaneThe number of a lane to restrict a library to: 1, 2, or 1+2 (default). If you are using the individually addressable lanes add-on with two library pools, lane 1 refers to the Library well, and lane 2 refers to the AUX well.
ProjectThe name of a project to group samples together. Each name can include case-sensitive alphanumeric characters, hyphens (-), and underscores (_).
Project names for samples must exactly match to successfully group samples together. Make sure no sample is assigned to more than one project. Bases2Fastq assigns any samples missing a project to a default project named DefaultProject.
ExternalIDAn alternative sample name or other external identifier to associate a library with. Each identifier can include 1–64 alphanumeric characters, hyphens, and underscores.

Recording Index Sequences

The index sequences recorded for an experimental library depend on the library prep workflow and --force-index-orientation argument in Bases2Fastq. When the argument is used, Bases2Fastq uses the orientation recorded in the run manifest. By default, Bases2Fastq detects and uses the correct index sequence orientation regardless of the orientation recorded in the run manifest.

Sample to Index Mapping

A repeated sample name links the specified index sequences to each other, so you must consistently capitalize sample names. Single or dual indexes can be specified as follows.

  • If you specify multiple indexes for Index 1 and Index 2 in the same row, Bases2Fastq uses all possible pairwise combinations.
  • In the SampleName column, enter the name of each library in the run.
  • In the Index1 and Index2 columns, enter the index sequences for each library in the same orientation.
    • For unindexed libraries, leave the Index1 and Index2 columns blank.
    • For single-indexed libraries, leave the Index2 column blank.

Index Orientation

When recording sequences in the Index1 and Index2 columns, use the same orientation for each sequence in a column. Entering the wrong sequences or mixing orientations affects index assignment.

  • For the Adept Workflow, enter the third-party index sequences.
    • If orientation detection is enabled in Bases2Fastq, enter the third-party index sequences as found in documentation.
    • If orientation detection is disabled in Bases2Fastq, enter the third-party index sequences in the correct orientation. For guidance, see Read Orientation.

Index Sequence Selection

Read Orientation

The Adept Workflow depends on a third-party kit, so an Adept library has P5 and P7 sides. The P5 and P7 sequences are not Element components. In contrast, the Elevate Workflow uses Element indexes and adapters to prepare libraries with SP5 and SP27 sides.

AVITI OS v2.0.0 or later sequences the library and the complementary sequence, including any indexes. Index 1, Index 2, and Read 1 occur in order on the P5 or SP5 side. The run then performs Read 2 on the P7 or SP27 side.

Figure 2: Sequencing Adept and Elevate libraries


Custom Sample-Level Metadata

An optional addition to the Samples section, custom columns specify additional key-value metadata for samples. Custom columns must meet the following requirements:

  • Each custom column name is unique, including case-sensitive variations.
  • A custom column cannot have the same name as a required column.
  • When a sample name is repeated, each corresponding value in the custom column must match exactly.
  • The key character limit is 1–64. Valid characters include lower- and upper-case letters, numbers, hyphens, and underscores.
  • The value character limit is 0–255 ASCII characters.