[Determination of hydrazine in prednisolone by derivatization-gas chromatography-triple quadrupole mass spectrometry].

Prednisolone is an adrenal glucocorticoid drug with immunosuppressive, anti-inflammatory, anti-allergic, and antiviral effects that are widely exploited in clinical treatment. The hydrazine residue to prednisolone directly affects medication safety and threatens the patient's health. At present, there are no relevant laws, regulations, and standards to control the residual limit of hydrazine in drugs at home or abroad. Therefore, a simple, rapid, accurate, reliable, sensitive, and selective method is urgently needed for the determination of trace hydrazine in prednisolone. Hydrazine has strong polarity and reductivity, with unstable physical and chemical properties, thus being easily oxidized. In addition, because of the lack of chromophores and low molecular weight, the detection of hydrazine is very difficult. Therefore, a derivative reagent should be introduced to reduce its polarity and generate a derivative product with a high molecular weight as well as stable physical and chemical properties. Acetone, as a common laboratory reagent, is inexpensive and can rapidly react with hydrazine; therefore, it is an ideal derivative reagent for the determination of hydrazine. In this study, a method based on precolumn derivatization with gas chromatography-triple quadrupole mass spectrometry (GC-MS/MS) was developed for the determination of hydrazine in prednisolone by optimizing the derivatization reagent, GC and MS conditions, solvent system, and derivatization conditions. Method validation was then carried out using the established method, and the results were satisfactory. In this study, 1 g of prednisolone sample was weighed and placed in a 10 mL centrifuge tube with a plug; then, a methanol-dichloromethane dilution solvent (14∶23, v/v) was added to the scale line, and the sample was vortexed until completely dissolved. About 100 μL of the test solution prepared above was pipetted into the sample vial, followed by the addition of 900 μL acetone. The resulting solution was vortexed and mixed well. The sample was diluted and derivatized simultaneously in acetone solution, acetone/methanol-dichloromethane dilution solvent (9∶1, v/v), and then detected and analyzed by GC-MS/MS. In this study, the derivatization reaction between hydrazine and acetone did not require the addition of acetic acid and ultrasound conditions, or the use of other reagents for the extraction operation. The reaction was instantaneous, and rapid determination of hydrazine in prednisolone could be achieved. The standard curve was obtained with a good correlation coefficient (r2=0.9999) in the range 1-12 μg/L. The limits of detection and quantitation were 0.03 mg/kg and 0.10 mg/kg, respectively. The relative standard deviation (RSD) of injection precision was 1.10%. The recoveries and repeatability were good; the recoveries of low-, medium-, and high-concentration spiked samples were 96.15%-96.46% at spiked concentrations of 1, 6, and 12 μg/L, respectively, and the corresponding RSDs were 1.77%-2.12%. The intermediate precision was good, and the RSD of the determination results obtained on the same instrument by different laboratory technicians at different times was 1.77%. The durability was good, and the degree of influence of the detection results was studied by changing the chromatographic conditions. Under the original condition or conditions with initial column temperature ±5 ℃, heating rate ±2 ℃/min, or column flow rate ±0.1 mL/min, the hydrazine content in the sample solution at a spiked concentration of 6 μg/L was detected, and the RSD of the detection results was 2.58%. The established method was applied to detect hydrazine in a prednisolone standard substance procured from the market and nine batches of prednisolone samples provided by a pharmaceutical company. No hydrazine was detected in any of these samples. The established method is simple, reliable, highly sensitive, and highly selective, and it can be applied for the detection of hydrazine in prednisolone.