Direct Insertion Probe

Direct Insertion Probe

Direct Insertion Probe

What is a Direct Insertion Probe (DIP)?

The Direct Insertion Probe (DIP) is used to introduce less volatile samples into the ion source of the mass spectrometer. It consists of a long rod with a sample holder on the tip. A solid or liquid sample is placed in the holder, also called the nest, on the end of the probe. The probe enters the vacuum system through a series of vacuum interlocks, so the sample cup is nested against the ion source.

The probe is inserted past the first Teflon seal. The roughing valve is opened to evacuate the area between the first Teflon seal and the ball valve. After about 5 to 10 seconds, the probe is pushed past the second Teflon seal; then, the ball valve is slowly opened and the end of the probe that holds the sample is pushed into the high vacuum chamber until it rests in the source. Heating the probe causes the sample to volatilize into the source. A heater/sensor assembly allows the temperature of the probe tip to be carefully controlled or temperature-programmed.

Direct Insertion Probe Advantages

  1. Allows spectra of relatively nonvolatile compounds to be obtained

  2. minimum sample preparation

Direct Insertion Probe Disadvantages

  1. samples must be relatively pure

  2. requires a valving system

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