The effect of storage upon cyanide in blood samples

Area of Science:

• Forensic Toxicology
• Clinical Chemistry
• Biochemistry

Background:

• Accurate quantification of cyanide in biological samples is crucial for clinical diagnosis and forensic investigations.
• Understanding the stability of cyanide in collected blood samples is essential for reliable testing.
• Potassium cyanide is a common reference standard, but its stability in blood matrices requires evaluation.

Purpose of the Study:

• To assess the stability of potassium cyanide in human blood samples under various storage conditions.
• To determine the extent of cyanide loss upon atmospheric exposure and during refrigerated and frozen storage.
• To inform best practices for sample collection and storage in cyanide testing.

Main Methods:

• Human blood samples were spiked with potassium cyanide at four different concentrations.
• Samples were exposed to atmospheric conditions for up to 10 minutes.
• Additional spiked samples were stored in stoppered tubes at -20°C and 4°C for up to 6 months.
• Cyanide levels were analyzed to determine degradation over time and under different conditions.

Main Results:

• Significant loss of cyanide was observed when spiked blood was exposed to the atmosphere for up to 10 minutes.
• A notable decrease in cyanide concentration occurred during storage at both -20°C and 4°C for up to 6 months.
• Higher initial concentrations of potassium cyanide showed a more pronounced loss during storage.

Conclusions:

• Potassium cyanide in human blood is unstable and subject to degradation.
• Atmospheric exposure and prolonged storage, even at low temperatures, lead to significant cyanide loss.
• These findings highlight the need for prompt analysis of cyanide samples and careful consideration of pre-analytical variables.