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 r(2)=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.