Amperometric Detection of Bacillus anthracis Spores: A Portable, Low-Cost Approach to the ELISA

Figure 1

Amperogram of a typical PHAD run. Closed circuit measurements are indicated by a diamond symbol. Otherwise, the PHAD instrument is in “open circuit” mode during which no measurements occur. A1–A10 are used to discharge the electrode. During measurements B1-C10 used blank substrate buffer is replaced with fresh (after C10 blank buffer is replaced with sample substrate buffer) 45–50 seconds prior to subsequent “B” measurement. Between B1 and C8, an offset knob is adjusted after each B, but before subsequent C measurement, to bring background near zero. Averaged background is subtracted from sample signal.