Formaldehyde Monitors

 

EXTREMELY PRECISE MIXING RATIO, EXTREMELY SHARP TIME RESOLUTION

Aerodyne’s trace gas monitor for formaldehyde (HCHO) has exceptionally fast response time, high sensitivity and  chemical specificity.  The measurement sensitivity is at least 0.1 ppb in one second and 0.03 ppb in one minute.  This high sensitivity and fast time response make Aerodyne’s formaldehyde monitor significantly more capable and versatile than other commercial monitors.

The figure at right demonstrates this sensitivity.  The upper trace is the formaldehyde mixing ratio in scrubbed room air plotted versus time for a one hour period.  The Allan plot in the lower half of the figure shows the precision as a function of averaging time.  Note that the one second precision is 32 ppt or three times less than our conservative specification of 100 ppt.

The second figure shows a typical spectrum acquired with a one second time constant.  In this instrument screen  shot, the green trace is the data and the nearly perfectly matched blue spectrum is the spectral model.  Formaldehyde is present at 21 ppb.  There are also clear spectral peaks due to formic acid and water – both of which are also simultaneously monitored with high sensitivity. 

 

Specifications

Molecule

HCHO

Laser Frequency

~1765 cm-1

Precision (1 s)

0.1 ppb(1 s)

0.03 ppb (60 s)

Accuracy

8%  or 0.1 ppb

Primary time response

0.1 seconds with 300 liter/min pump