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.