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HTEC-500
13.
Storage of a Standard Sample
Substances that are active to the ECD are easily oxidized and should be stored carefully. Check the
conditions where they are stable.
The methods to store a standard sample for some typical substances are described below:
Catecholamine:
Put the standard in cold storage with 0.1 M HCl containing 1 mg/mL EDTA-2Na at a
concentration of 1 ng/
μ
L. Dilute using 20 mM phosphate buffer (pH3.5) containing
20 mM EDTA-2Na for every analysis. It dissolves easily when the concentration is less
than pg/
μ
L.
Indoleamine:
Put the standard in cold storage with 0.1 M CH3COOH containing 1 mg/mL EDTA-2Na
at a concentration of 1 ng/
μ
L. Dilute using 20 mM phosphate buffer (pH3.5)
containing 20 mM EDTA-2Na for every analysis. It decomposes easily when the
concentration is less than pg/
μ
L.
ACh:
The standard is relatively stable but is easily metabolized by unwanted bacteria. To
avoid breeding of bacteria, the standard should be diluted using 20 mM phosphate
buffer (pH3.5) containing 20 mM EDTA-2Na.
Glutathione:
Put the standard in cold storage with 0.1 M HCl containing 1 mg/mL EDTA-2Na at a
concentration of 1 ng/
μ
L. This can be used for analysis for approximately one week.
Dilute with the mobile phase for a glutamate enzymatic assay. The mobile phase
contains HDTMA which prevents bacterial growth.
