Determination of hydroxyurea in serum or plasma using gas chromatography-mass spectrometry (GC-MS).

Hydroxyurea is an antineoplastic drug, which is also widely used in the treatment of sickle cell disease. Various methods including colorimetry, high performance liquid chromatography, and gas chromatography-mass spectrometry (GC-MS) are available for the assay of hydroxyurea. In the gas chromatography method described, the drug is extracted from serum, plasma, or urine using ethyl acetate and phosphate buffer (pH 6).

Determination of benzoic acid in serum or plasma by gas chromatography-mass spectrometry (GC/MS).

Nonketotic hyperglycinemia (NKH), a metabolic disorder due to defects in the glycine cleavage system, leads to the accumulation of toxic levels of glycine. Glycine levels in these patients may be lowered by sodium benzoate treatment. Benzoic acid binds to glycine to form hippurate, which is subsequently eliminated through the kidneys.