The VOC levels in four vehicles were monitored by GCMS/HPLC and SIFT-MS. These vehicles were conditioned with doors closed and windows rolled up and tested in a temperature and humidity controlled environment at Allen Park Test Lab.
One stream enters the SIFT-MS for analysis, and the other stream enters the sampling system where discrete volumes are collected onto two thermal desorption (TD) tubes and two DNPH cartridges.
The SIFT-MS evaluated was a Voice200ultra from Syft Technologies.
In SIFT-MS, the ion-molecule reactions inside the flow tube are well understood and occur at known reaction rates.
Gas samples for [N.sub.2]O were taken after SIFT-MS samples (see below) had been taken and were analysed within 24 h.
SIFT-MS analysis was performed according to Milligan et al.
For Day 1, soil depth 1, a regression of calculated N[H.sub.3(g)soil] (Eqn 4) and SIFT-MS N[H.sub.3(g)] headspace concentrations for individual replicates demonstrated a linear relationship ([r.sup.2] = 0.96; P < 0.01) for the 0-500 kg N/ha urine treatments (Fig.
The scientists monitored the aroma profiles by SIFT-MS
for six weeks.
SIFT-MS has been primarily used for on-line quantification of trace gases in human breath for clinical diagnosis and therapeutic monitoring.
As in earlier research, propanal was the dominant volatile compound detected by SIFT-MS. Its concentration rose significantly within a few days of initiating the experiment.
The samples were analyzed for 36 compounds, including aldehydes, alcohols, ketones, thiols and thioethers, using commercial SIFT-MS instrumentation.
These results indicate the potential of SIFT-MS. Its rapid analysis proved to be highly accurate in profiling the flavors involved in infant formula.