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Today we are talking about the Dosage of urinary Trans 1.2 Cyclohexanediol
using an EXCLUSIVE KIT for this specific analysis.

The trans 1.2 Cyclohexanediol together with 1.4 Cyclohexanediol is one of
the products of the Cyclohexane metabolism.

It is present in the urine of subjects exposed to this solvent, but also to
substances such as Cyclohexanol and Cyclohexanone.

The metabolization of cyclohexane, by liver microsomal enzymes, leads to
the formation of diols.
In a survey conducted on subjects exposed to Cyclohexane,
the various urinary metabolites were found in the following proportions:
– Cyclohexanol 0.5 %
– 1.2-Cyclohexanediol 23.4%
– 1.4-Cyclohexanediol 11.3%

The metabolic pattern is practically the same for exposure to cyclohexanol
and cyclohexanone.

The elimination half-life of the diols following inhaled cyclohexane exposure is
14-18 hours.

The Instrumental Technique used for the determination of trans 1,2
Cyclohexanediol is Gaschromatography with a Flame Ionization
Detector (FID) but a Mass Detector may also be used.

This method is applicable routinely to the biological monitoring of subjects
professionally exposed to cyclohexane.

It has to be evaluated the possibility of simultaneous exposure
to cyclohexanol and cyclohexanone,
which lead to the excretion of the same metabolites.

From the analysis of the correlation between the cyclohexane environmental
data and the urinary concentrations of the metabolites, it has emerged that
the most reliable indicator is the trans 1.2 Cyclohexanediol because it is:

– More sensitive
–  Specific
– Better correlated with the external dose of the solvent

Using the sum of the two indicators, the trans 1.2 Cyclohexanediol and the
1.4 Cyclohexanediol, does not obtain better results and therefore
it is sufficient to dose 1.2 Cyclohexanediol.

Let’s start now to illustrate the method to determine the trans 1.2 Cyclohexanediol
in urinary matrix, taking as example an analytical session of

  • 7 Urinary samples
  • 1 Calibrator
  • 2 Controls, Level 1 and 2

The chromatographic run time is 26 MINUTES
and for this sequence of 7 samples, all results will be obtained, including
calibrator injections and two controls,
in just over 4 hours of instrumental work.

This is a typical Chromatogram, in which the peak of 1.2 Cyclohexanediol is
at 15.9 minutes and the peak of the Internal Standard comes out at 8.7 minutes.


The time taken for this analysis is as follows:

– 15 minutes to prepare 7 samples, 1 calibrator, and 2 controls with
the hydrolysis reagent
–  60 minutes incubation at 110 °C
–  15 minutes to add in order the neutralizing solution, the stabilizer
and the extraction solution
– 10 minutes in the rotary agitator
–  10 minutes in the centrifuge at 3000 rpm for a total of 2 hours of
preparatory phase
–  270 minutes to analyze all the samples



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