Sensitive determination of hydrazine in water by gas chromatography–mass spectrometry after derivatization with ortho-phthalaldehyde

A gas chromatography–mass spectrometric (GC–MS) method has been established for the determination of hydrazine in drinking water and surface water. This method is based on the derivatization of hydrazine with ortho-phthalaldehyde (OPA) in water. The following optimum reaction conditions were established: reagent dosage, 40 mg mL−1 of OPA; pH 2; reaction for 20 min at 70 °C. The organic derivative was extracted with methylene chloride and then measured by GC–MS. Under the established condition, the detection and the quantification limits were 0.002 μg L−1 and 0.007 μg L−1 by using 5.0-mL of surface water or drinking water, respectively. The calibration curve showed good linearity with r2 = 0.9991 (for working range of 0.05–100 μg L−1) and the accuracy was in a range of 95–106%, and the precision of the assay was less than 13% in water. Hydrazine was detected in a concentration range of 0.05–0.14 μg L−1 in 2 samples of 10 raw drinking water samples and in a concentration range of 0.09–0.55 μg L−1 in 4 samples of 10 treated drinking water samples.

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► New derivatization method of hydrazine with ortho-phthalaldehyde in water.
► A simple, rapid and sensitive method by GC–MS.
► The reaction conditions were optimized.
► Very small amount of sample and solvent is needed.