Identification and Quantification of Malodorants Generated Upon Terminal Heat Sterilization of the Antibiotic Sterile Solution Lincocin

Abstract

The odor in sterile solution lincomycin hydrochloride (S.S. Lincocin) subjected to terminal heat sterilization is due primarily to methyl mercaptan (CH₃SH), secondarily to dimethyl disulfide (DMDS). Methyl mercaptan is generated by cleavage of the methyl mercaptyl group from the pyranoside ring in lincomycin; DMDS results from subsequent oxidation of CH₃SH. A splitless headspace GC method was developed to detect and quantify the two compounds. Peak identification was made by injection of authentic standards in conjunction with chromatographic sniffing. CH₃SH and DMDS were quantified by standard addition and were found to be present at about 1 and 0.05 ppm, respectively, in a lincomycin solution heated at 80°C for 30 minutes. These levels are well above the documented odor thresholds for these two compounds in water. In contrast, no CH₃SH was detected over unheated lincomycin. The amounts of CH₃SH and DMDS generated correspond to a 0.003% decrease in drug concentration.

Key Words:

• Headspace analysis
• odor analysis
• pharmaceutical analysis
• chromatographic sniffing