Optimising cell temperature and dispersion field strength for the screening for putrescine and cadaverine with thermal desorption-gas chromatography-differential mobility spectrometry.

Biogenic amines, and putrescine and cadaverine in particular, have significant importance in the area of food quality monitoring, and are also potentially important markers of infection, for cancer, diabetes, arthritis and cystic fibrosis. A thermal desorption-gas chromatograph-heated differential mobility spectrometer was constructed and the significant effect of interactions between cell temperature and dispersion field strength on the observed responses studied. The experiment design was a Box-Wilson central composite design (CCD) over the levels of 10-24 kVcm(-1) for dispersion field strength and 100-130 degrees C for cell temperature. The optimum values were estimated to be 16.22 kVcm(-1) and 116 degrees C for putrescine and 14.78 kVcm(-1) and 112 degrees C for cadaverine, respectively with an ammonia dopant at 19 mgm(-3). An amine test atmosphere generator was constructed and produced stable concentrations of putrescine (7 mgm(-3)) and cadaverine (4 mgm(-3)) vapours at 50+/-0.5 degrees C. Tenax TA-Carbotrap adsorbent tubes were used to sample putrescine and cadaverine vapour standards and a linear response function over the range of sample masses 5-20 ng was obtained at 15.0 kVcm(-1) 115 degrees C, with a R(2) of 0.99 for both putrescine and cadaverine. The sample mass at the limit of detection was estimated to be 3 ng for putrescine and cadaverine. Preliminary data from sampling the headspace of chicken meat revealed a 62% increase in the recovered masses of putrescine from 0.84 to 1.36 ng in the sampled air.