Developing a trace level GC-MS method for detecting methylhydrazine in an experimental drug substance.

Methylhydrazine (NH(2)NHCH(3), CAS 60-34-4) is a highly reactive reducing agent used as an intermediate for synthesizing an experimental drug substance. Methylhydrazine is a known mutagen, an animal carcinogen, and a suspected human carcinogen. A gas chromatography-mass spectrometry method was developed as a limit test method for analyzing trace levels of methylhydrazine in the experimental drug substance. The method utilizes acetone as a dissolving solvent for the drug substance and a derivatizing agent for methylhydrazine in the meantime, thus eliminating the need for post-derivatization sample clean-up prior to analysis. The gas chromatographic (direct injection) conditions provide good separation for the acetone-methylhydrazine derivative (acetone methylhydrazone) from matrix interference, and mass spectrometric detection (selected ion monitoring mode, m/z 86) allows sufficient sensitivity for detecting 1 part per million methylhydrazine relative to the drug substance.

Gas chromatography-mass spectrometry determination of the pentafluorobenzoyl derivative of methylhydrazine in false morel (Gyromitra esculenta) as a monitor for the content of the toxin gyromitrin.

The main toxic compound found in false morel (Gyromitra esculenta) is acetaldehyde-N-methyl-N-formylhydrazone (gyromitrin). This paper describes a method of determining the total hydrazones content based on acid hydrolysis of gyromitrin and other related hydrazones in air-dried false morel followed by derivatisation of methylhydrazine with pentafluorobenzoyl chloride. The derivative, tris-pentafluorobenzoyl methylhydrazine (tris-PFB-MH) is analyzed by gas chromatography-mass spectrometry. The overall precision of the method is better than 10% (relative standard deviation) for 0.5 ng/microl methylhydrazine in solution. The minimum detectable concentration of methylhydrazine (tris-PFB-MH) by this method is estimated to be approximately 12 pg/microl, which is equal to 0.3 microg/g dry matter (DM) of false morel.

Determination of hydrazine, monomethylhydrazine, 1,1-dimethylhydrazine, and 1,2-dimethylhydrazine by nonaqueous capillary electrophoresis with amperometric detection.

The present study is concerned with the application of nonaqueous capillary electrophoresis (NACE) with electrochemical detection (ED) to the separation and quantitative determination of hydrazine (Hy) and its methyl derivatives. The best performance of NACE-ED was found when using 4 mM sodium acetate/10 mM acetic acid/methanol: acetonitrile = 1:2 as the running buffer, with a bare platinum working electrode set at +1.0 V in an end-column amperometric detection cell. The choice and ratio of suitable solvents for the separation and injection media played an essential role for the performance characteristics of the method. The limits of detection for Hy, methylhydrazine, symmetrical dimethylhydrazine, and unsymmetrical dimethylhydrazine were 5, 2, 12, and 1 ng/mL, respectively. This is between one and two orders of magnitude lower than that achieved by previously reported CE-ED methods in aqueous buffer systems in conjunction with various types of chemically modified electrodes. The practical utility of the new NACE-ED methodology is demonstrated in terms of the determination of traces of Hys in spiked environmental samples containing a wide range of explosives and related compounds.

Detection of hydrazine, methylhydrazine and isoniazid by capillary electrophoresis with a 4-pyridyl hydroquinone self-assembled microdisk platinum electrode.

Capillary electrophoresis (CE)/electrochemical detection (EC) for the simultaneous detection of hydrazine, methylhydrazine, and isoniazid has been developed with a 4-pyridyl hydroquinone self-assembled microdisk platinum electrode. Such an electrode has very high catalytic ability for hydrazines and they could be detected even at 0.0 V. The responses for hydrazine, methylhydrazine, and isoniazid are linear over 3 orders of detected concentration and of magnitude of 0.2-400 microM, 0.2-400 microM, 0.5 microM-2 mM, with correlation coefficients of 0.9998, 0.9991, and 0.9982, respectively. And they could be detected to levels of 0.1, 0.1 and 0.2 microM, respectively. This modified electrode was found to be very stable and reproducible when continuously used as detector for capillary electrophoresis for period of at least 4 weeks with no apparent loss of response.

Determination of monomethylhydrazine with a high-throughput, all-fiber near-infrared spectrometer based on an integrated acoustooptic tunable filter and an erbium-doped fiber amplifier.

A novel integrated acoustooptic tunable filter (IAOTF) has been developed. This tunable filter is based on the Bragg interactions between waveguide and surface acoustic waves. Compared to (bulk) AOTF, its advantage include all-fiber construction, smaller size, narrower spectral resolution (1.7 nm), higher diffraction efficiency (37%), and lower rf power requirement (150 mW). A relatively narrow spectral tuning range (about 80 nm) is the only drawback for this integrated tunable filter. However, this disadvantage was overcome by judiciously using the filter for measurements in which its tuning range is coincident with the light source and also with absorption bands of analytes. In fact, an all-fiber, compact, high-throughput near-infrared spectrophotometer has been successfully constructed by synergistic use of this integrated AOTF and the erbium-doped fiber amplifier (EDFA), which has been shown to provide high intensity and wide spectral band-width in the near-infrared region from 1500 to 1600 nm. This spectral region is particularly useful for the determination of samples which have O-H and/or N-H groups. The all-fiber nature, compactness, high throughput, and high sensitivity of this spectrophotometer make it particularly suitable for on-line and real-time detection of trace gases in hostile environments, including leak detection of monomethylhydrazine (at a limit of detection of 191 ppm), which is often used as the hypergolic propellant for the space shuttle thruster systems.

Ion mobility spectrometry of hydrazine, monomethylhydrazine, and ammonia in air with 5-nonanone reagent gas.

Hydrazine (HZ) and monomethylhydrazine (MMH) in air were monitored continuously using a hand-held ion mobility spectrometer equipped with membrane inlet, 63Ni ion source, acetone reagent gas, and ambient temperature drift tube. Response characteristics included detection limit, 6 ppb; linear range, 10-600 ppb; saturated response, >2 ppm; and stable response after 15-30 min. Ammonia interfered in hydrazines detection through a product ion with the same drift time as that for MMH and HZ. Acetone reagent gas was replaced with 5-nonanone to alter drift times of product ions and separate ammonia from MMH and HZ. Patterns in mobility spectra, ion identifications from mass spectra, and fragmentation cross-sections from collisional-induced dissociations suggest that drift times are governed by ion-cluster equilibria in the drift region of the mobility spectrometer. Practical aspects including calibration, stability, and reproducibility are reported from the use of a hand-held mobility spectrometer on the space shuttle Atlantis during mission STS-37.

An in vitro study on the interaction between dimethylnitrosamine and nucleic acids via a microsomal system.

Radioactive alkylated bases, ribose or phosphate, were never found either in acid and alkaline hydrolysates of polyribonucleotides or in alkaline hydrolysates of DNA after incubation with 14C-dimethylnitrosamine (DMNA) in a microsomal system. Two radioactive compounds, which were co-chromatographed with methylamine and N-methylhydrazine, respectively, on column, paper, and thin-layer, were always detected. They differed from the compound derived from 7-methylguanosine after the alkali-mediated fission of the imidazole ring in its molecule. The in vitro system employed well represents the in vivo situation (7-methylguanine which is liberated from DNA after acid hydrolysis); however, it has given results which do not agree with the generally-accepted mechanism of DMNA alkylation at the N-7 position of guanine.

The alkylation of nucleic acids of rat and mouse in vivo by the carcinogen 1,2-dimethylhydrazine.

1,2-Dimethylhydrazine, in contrast to 1-methylhydrazine, is a potent carcinogen for the colon in rats and mice. 1,2-[(14)C]Dimethylhydrazine was administered to rats and mice in doses which are carcinogenic following a single dose in the former species, or carcinogenic on repeated administration in the latter species, and the rate of (14)CO(2) exhalation was measured. Exhalation of (14)CO(2) was also studied after administration of single doses of 1-[(14)C]methylhydrazine to mice. Incorporation of radioactivity into the nucleic acids of a variety of organs was found at a time after injection (about 6 h) when (14)CO(2) production from both compounds was virtually complete. Methylation of nucleic acids of liver and colon, as indicated by the formation of 7-methylguanine, was observed after treatment with 1,2-dimethylhydrazine and to a smaller extent by a factor of about 10 after treatment with 1-methylhydrazine. Less than 1% of a single dose of 1,2-[(14)C]dimethylhydrazine was excreted in the bile of rats as determined by chemical and radioactivity assays. The similarities of the biological and biochemical actions of 1,2-dimethylhydrazine with those of some nitroso compounds and of cycasin (methylazoxymethanol glucoside) are emphasized.