In 11B measurements, similarly to 29Si measurements, background signals may sometimes be a problem. Although the background derived from sample tubes can be reduced by using quartz or PTFE sample tubes, those from glass and ceramics of the probe cannot be removed.
JEOL revised the glass and ceramic materials of the standard probe parts and successfully reduced the 11B background signals.
The above figure shows the 11B spectra observed using a 400 MHz spectrometer and 5 mm -(left) and 10 mm -(right) probes. The 11B spectra without sample tubes (top) manifest almost no background signals derived from the probes.
The middle and bottom figures show the 11B spectra of phenylboric acid (1.0 x 10-2 M). Although heat-resistant glass sample tubes are commonly used, they may cause background (bottom). Therefore, quartz or PTFE sample tubes (middle) are recommended in 11B measurements.