INTRODUCTION
Glycol-based antifreeze liquids, commonly composed of ethylene glycol or propylene glycol, have several important uses in various applications:
- Automotive cooling: one of the primary uses of glycol-based antifreeze is in internal combustion engines. It helps regulate the temperature of the engine by preventing freezing and overheating. The antifreeze mixture is circulated through the engine and radiator, preventing coolant from freezing in cold temperatures while also raising the boiling point to prevent overheating.
- Heat transfer: glycol-based antifreeze is used as a heat transfer fluid in industrial processes. It efficiently carries heat away from equipment, such as HVAC systems, refrigeration units, and solar water heaters. The fluid’s high heat capacity and low freezing point make it suitable for maintaining stable operating temperatures.
- Airplane de-icing: glycol-based antifreeze solutions are sprayed onto aircraft to remove ice and frost before take-off. These fluids effectively melt frozen deposits on the aircraft’s surfaces, ensuring safe flight conditions.
- Refrigeration: in refrigeration systems, glycol-based antifreeze helps maintain consistent temperatures and prevents freezing of refrigerant lines and evaporators in low-temperature applications.
It is important to note that while glycol-based antifreeze liquids offer numerous benefits, they should be handled with care due to their toxicity. Proper disposal and management are essential to prevent environmental contamination. Ethylene glycol is highly toxic to humans and animals. Ingesting even small amounts can lead to severe health complications and potentially be fatal.
Ethylene glycol is metabolized in the body through a series of enzymatic reactions, ultimately forming toxic metabolites. These metabolites can cause damage to various organs, particularly the kidneys, central nervous system, and heart1
Ethylene glycol toxicity is a serious and potentially life-threatening condition. Immediate medical attention is necessary if there is suspicion of exposure or ingestion. Prevention, proper handling, and responsible disposal of ethylene glycol-containing products are key to avoiding accidental poisoning.
Several detection methods for glycols are present in the scientific literature. In surface and waste waters, traces of ethylene glycol, propylene glycol and diethylene glycol can be detected using GC-FID, with a limit of detection of 0.02 ppm glycol2.
A method for the monitoring of workplace air quality and the presence of toxic glycols was presented by Giesen et al., using a sampling system, for a sample volume of 40L, with what they achieved a 0.5 mg/m3 limit of quantification3..
In biological samples, the most commonly used methods reported in literature for detecting glycols are based on gas chromatography using either flame ionization detector (FID) or mass spectrometry (MS), with derivatization. The limits of detection and quantification are in the sub-µg/mL range 4-5.
In antifreeze samples, only one method (spectrophotometric) was identified. Faizullah and Jabbar developed an extraction, pre-concentration method to detect EG in antifreeze samples using an indirect determination (Malaprade reaction) 6.
To our knowledge, this is the first developed and validated method for the simultaneous detection and quantification of glycols (and their isomers) in antifreeze samples using GC-MS direct injection technique. This method can be applied by laboratories involved in analysis of counterfeit products and, more important, by the manufacturers of antifreeze liquids, in order to assess the exact composition of their final products. The molecular structures of the glycols analyzed are presented in Figure 1.