Bracketing
Bracketing decides which calibration injections belong on the curve for each sample. Set it in Batch properties when you create the batch. The method stores the mode.
The modes are:
| Mode | What it does |
|---|---|
| Initial | One curve. When any calibration sample is present, every stored response is replaced. This is the default. |
| Partial | One curve. Only responses whose dose has a live calibration sample are replaced. Other stored responses stay and are used as curve points. |
| Bracket | One curve per bracketing set. Stored responses in that set are replaced. A level that is missing from the set is not borrowed. |
| Bracket with borrow | Same as Bracket, and a missing level is borrowed from the adjacent bracket. |
Initial and Partial do not walk the batch as brackets. Every sample uses the one curve.
How a bracket is formed
For Bracket and Bracket with borrow, samples are ordered by acquisition time. A calibration block is a run of samples whose type is Calibration with nothing else in between. Sample, QC, CCV, Blank, and Solvent are a non-calibration block. A CCV is quantitated with that block and stays out of the fit. See Continuing calibration verification.
- Each calibration block is its own bracket and uses only its own responses.
- Each non-calibration block uses the calibration block immediately before it and the calibration block immediately after it.
The whole batch is included. Samples are not required to sit between two calibration blocks.
- Samples before the first calibration block have no leading calibrators. They use only the following calibration block, when there is one.
- Samples after the last calibration block have no trailing calibrators. They use only the preceding calibration block.
- A batch with no calibration samples produces no calibration responses for those brackets.
- Two calibration injections in a row with no unknown between them are one block, not two brackets.
Bracket with borrow still builds those same blocks. If a dose is missing inside a block, the response is taken from the neighboring bracket. Bracket leaves that level out.
Calibration groups
A sample has at most one Cal group. Each cal group is its own calibration scope: its own responses, curve, and brackets. Samples with no cal group use the normal calibration mode.
Cal group Mode is separate from the four calibration modes above.
- Calibration is the normal curve. A fortified Sample or QC in that group is spike recovery: the curve still comes from the calibration samples. Pair the unspiked vial with the spike by SpikeGroup, not by the Cal group. See Spike recovery.
- Standard addition estimates one shared native from the Sample aliquots in that group. See Standard addition.
Failed calibration checks
A calibration point that fails recovery or R² stays in the bracket. The check flags the result. It does not remove the point from the curve and it does not move the sample into another bracket. See Checks.
QC injections are never calibration blocks, so they do not start or end a bracket. They are quantified with the bracket they fall in.
Saved batches for Initial, Partial, Bracket, and Bracket with borrow are in Example batches.