This study aimed to identify the related substances of lorazepam tablets by liquid chromatography mass spectrometry (LC-MS). To separate the related substances of lorazepam tablets, gradient elution was performed using acetonitrile and 0.1% acetic acid -20 mmol/L of ammonium acetate as mobile phase on Inert Sustain C18 (250 mm × 4.6 mm, 5 μm).The accurate mass and elemental composition of the parent ions and their product ions of related substances were determined by electrospray-ionization quadrupole time-of-flight high resolution mass spectrometry (ESI-Q-TOF/MS).The structures of the related substances were identified by spectral analysis. Under the established analytical condition, lorazepam and its related substances were adequately separated, and 22 major related substances with content greater than 0.1% were detected and identified by hyphenated techniques in lorazepam tablets and their stressed samples.Among them, 5 were the impurities listed in the USP or EP, and the others were unknown related substances identified for the first time in this paper.The LC-MS technique can effectively separate and identify the related substances of lorazepam tablets, which provides some reference for quality control.

This article reported a prenatally diagnosed case of complete ring chromosome 15. A 38-year-old woman who conceived by in vitro fertilization and frozen embryo transfer underwent amniocentesis for prenatal diagnosis at 18 +5 weeks of gestation due to advanced maternal age. The result of G-banding karyotyping was mos 46,XX,r(15)[88]/45,X,-15[11]/46,XX,r(15;15)[1]. No numerical abnormalities of chromosomes or definite pathogenic copy number variations (CNVs) were detected by chromosomal microarray analysis. Amniocentesis was performed again at 31 +6 weeks of gestation. The result of genome copy number variation sequencing indicated no pathogenic CNV and fluorescence in situ hybridization on cultured amniocytes revealed nuc ish(15q)×1[15]/(15q)×3[5]/(15q)×2[80]. Based on all the prenatal diagnosis results, it was suggested that the fetus carried a complete ring chromosome 15. As the peripheral blood chromosomes of the couple were normal and no obvious abnormalities were detected by the prenatal ultrasound either in our hospital or another hospital, the pregnant woman decided to continue the pregnancy after genetic counseling and delivered a baby girl at 41 weeks of gestation. The girl showed no physical abnormalities during a seven-month follow-up.