MassQC Help > Metrics > Ion Source > Spray Instability          
Spray Instability

Spray Instability measures how often the ion current jumps or falls by more than 10 times between adjacent scans.

A Spray Instability number greater than zero indicates electrospray instability or sputtering of the spray tip.

The Spray Instability metric counts how many times the MS1 total ion current jumps or falls by a factor of 10 from one scan to the next. This metric is calculated over the time period defined by the "Retention Spread", that is the middle of the retention time when most of the peptides are eluting.

spray instability

Units:

Count

Optimal:

Zero: Any positive number indicates a problem.

For most metrics, the acceptable range of values is determined by the past performance of the LC-MS. The Spray Instability metric is different since the only acceptable value is zero.

What the Metric Detects:

A non-zero value for the Spray Instability metric means that the electro-spray is erratic.

Related Metrics:

The Spray Instability is only measured during the part of the elution defined by the Retention Spread metric. An unstable spray at the being or end of the elution time is not reflected in this metric.

Related Troubleshooting Topics:
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