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A Solid-Phase Microextraction Chamber Method for Analysis of Manure Volatiles

USDA-ARS, U.S. Meat Animal Research Center, P.O. Box 166, Clay Center, NE 68933. D.N. Miller, current address: USDA, ARS, Soil and Water Conservation Research Unit, 121 Keim Hall, East Campus, Lincoln, NE 68583

View larger version (21K): [in a new window]   Fig. 1. General schematic of the dynamic flow chamber slightly modified from the chamber described by Woodbury et al. (2006) showing the (1) low volume manure pan, (2) head space mixing fan, (3) four ports for clean air flow into the chamber, and (4) the exit port holding a portable solid-phase microextraction sampler.

View larger version (14K): [in a new window]   Fig. 2. Total ion current (IC) profiles for fresh (A) cattle C1 and (B) swine S2 feces. Major peaks marked with letters are identified in Table 3. Fiber exposure time = 5 min; flow rate = 1 L min–1 (16 cm s–1); chamber temperature = 20°C.

View larger version (16K): [in a new window]   Fig. 3. Relationship between total ion current (IC) bound to the solid phase microextraction (SPME) fiber for cattle C1 and swine S2 feces and (A) the time of fiber exposure to the air stream leaving the dynamic flux chamber [flow rate = 1 L min–1 (16 cm s–1); chamber temperature = 20°C] or (B) air flow rate leaving the chamber [fiber exposure time = 5 min; chamber temperature = 20°C].

View larger version (18K): [in a new window]   Fig. 4. Amount of (A) total ion current (IC) and (B) chamber air relative humidity and temperature with increasing time in the dynamic flux chamber for the cattle C1 and swine S2 feces. Fiber exposure time = 5 min; flow rate = 1 L min–1 (16 cm s–1); chamber temperature = 20°C.

View larger version (13K): [in a new window]   Fig. 5. Dependence of total ion current (IC) signals on (A) mass or (B) area of cattle C1 feces in the chamber. To increase the total IC signal, cattle C1 feces was stored overnight at 37°C and subsequently at 20°C for 2 wk. Fiber exposure time = 5 min; flow rate = 1 L min–1 (16 cm s–1); chamber temperature = 20°C.

View larger version (21K): [in a new window]   Fig. 6. Relationship between total ion current (IC) signal obtained from cattle C1 and swine S2 feces and the temperature of the feces. Fiber exposure time = 5 min; flow rate = 1 L min–1 (16 cm s–1).

View larger version (18K): [in a new window]   Fig. 7. The effect of storing (A) cattle C1 and (B) swine S2 fecal samples up to 5 wk in a freezer (–20°C), a refrigerator (4°C), and at ambient (20°C) temperatures on total ion current (IC) signal. Fiber exposure time = 5 min; flow rate = 1 L min–1 (16 cm s–1); chamber temperature = 20°C.

View larger version (14K): [in a new window]   Fig. 8. Relationship between total ion current (IC) signal and volatile organic compound (VOC) flux from standard mixtures of VOC. The standard error (SE) for VOC flux was calculated by regression analysis from rate of VOC mass loss. Mean total IC signal and SE calculated from seven to eight total IC measurements. Fiber exposure time = 5 min; flow rate = 1 L min–1 (16 cm s–1); chamber temperature = 20°C.