1. RFA 300 Rapid Flow Analyzer for histamine measurement by fluorimetry (Astoria-Pacific International, Clackamas, OR).
2. Filtered reagents for fluorimetry.
a. 0.73 M Phosphoric acid.
d. 1 N NaOH containing 1 mM EDTA.
f. Brij-saline-EDTA: 0.17 M NaCl, 1.5 mM EDTA, 0.015% Brij-35 (Perstorp Analytical, Silver Spring, MD).
i. OPT solution: 50 mg of OPT (Sigma, St. Louis, MO) recrystallized in Ligoine solvent (Eastman Kodak Co., Rochester, NY), 1 mL of spectranalyzed methanol (Fisher Scientific, Pittsburgh, PA), and 0.5 M99 mL of borate buffer.
3. Histamine standards (for fluorimetry).
a. Histamine dihydrochloride (molecular weight = 184.1).
b. Histamine (molecular weight = 111.0).
c. 1 mg/mL Histamine solution. (Note: 1 mg of histamine equals 1.66 mg of hista-mine dihydrochloride.)
d. Dilute the 1 mg/mL solution 1:1000 in 2% HClO4 to give 1 pg/ mL stock and store at -20°C in 6-mL aliquots.
e. 6 mL of 1 pg/mL histamine added to 294 mL of 2% perchloric acid = 20 ng/mg.
f. 50 mL of ~20 ng/mL standard added to 50 mL of 2% perchloric acid = 10 ng/mL.
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