## 2 Methods  
Plates of Potato Dextrose Agar (PDA) were prepared for both _Penicillium chrysogenum_ and _Aspergillus versicolor_. Plates of Corn Meal Agar (CMA) were prepared for _Stachybottys chartarum_. Growth media was autoclaved at 121\({}^{\circ}\) C for 15 minutes and plated under sterile conditions in a Biological Safety Cabinet. To further ensure the media was not contaminated, plates were incubated at room temperature for a week before samples were cultured. Samples were subsequently cultured in triplicate and were incubated at 30\({}^{\circ}\) C for one week. The plates were then examined and purified onto other uncontaminated PDA and CMA plates and incubated for another week at 30\({}^{\circ}\) C. A small 1 cm x 1 cm piece of mold and agar was then excised from each plate and aseptically transferred to \(\
u_{2}\) liter Mason jars. These jars were pre-lined with PDA or CMA, and served to allow headspace samples to be taken over successive weeks while offering the mold a constant and sufficient supply of a nutrient source.  
Solid-phase microextraction (SPME) parameters were adjusted through a series of optimization studies, where SPME fiber type, length of exposure, and volume of headspace were varied. Initially, the volatile organic components were extracted from the headspace of the vials using three different SPME fiber types: PDMS/DVB (65 \(\upmu\)m StableFlex), CAR/PDMS (75 \(\upmu\)m), and CW/DVB (70 \(\upmu\)m StableFlex). Blanks of all SPME fibers were run before exposure to the sample to eliminate carryover from previous exposures. Fibers were exposed to the sample for 1, 10, and 18 hours. It was ultimately determined that CW/DVB StableFlex fibers extracted the most compounds from the headspace at an exposure time of 18 hours, using \(\
u_{2}\) L Mason jars to house the mold samples. After exposing the fibers to the headspace of the _Aspergillus versicolor_, _Penicillium chrysogenum_, and _Stachybotrys chartarum_ mold samples, as well as mold-free PDA and CMA for 18 hours, they were introduced to the GC/MS for thermal desorption and analysis. To test the effect of time on odor signatures of mold species, the _Stachybotrys chartarum_ sample was analyzed using SPME-GC/MS for three consecutive weeks.  
A splitless injection was used on an Agilent Technologies HP5-MS capillary column with a length of 30 m, an outer diameter of 0.25 mm, and a film thickness of 0.25 \(\upmu\)m. Helium was used as a carrier gas, and had a flow rate of 1 milliter /minute. The initial temperature was 40\({}^{\circ}\)C, and that temperature was held for 5 minutes. Next, there was a 10\({}^{\circ}\)C/min increase to 280\({}^{\circ}\)C, and then that temperature was held for 1 minute. The mass spectral data from the resulting chromatograms was compared to the NIST 1998 library for identification.  
Figure 2: Photograph of initial Solid Phase Microextraction apparatus.  
Canine field tests were run with four pre-trained dogs at the Florida Canine Academy in Safety Harbor, Florida. The _Aspergillus versicolor_, _Penicillium chrysogenum_, and _Stachybotrys chartarum_ mold samples were placed in separate round plastic containers with punctured lids to allow the volatiles to escape. Negative controls were also set up which contained no toxic molds. The field tests were then executed in a double-blind fashion with an impartial evaluator to record all alerts and nonalerts for each dog, according to specifications set forth to increase reliability of canine field tests.