Scientists Jorn Chi Chung Yu, Garrett Lee Burleson, and colleagues in the Department of Forensic Science at Sam Houston State University in Texas have developed a new method for identifying gunshot residue without the presence of lead.
A simple and inexpensive sample preparation method followed by reversed-phase high performance liquid chromatography (RP-HPLC) was developed to quantify oxytetracycline (OTC), chlortetracycline (CTC), and tetracycline (TC) residues in prawns. The total analytical time, including sample preparation, was 15 min for each sample and no organic solvents were used in the sample preparation or chromatography stages.
Inlet discrimination is a problem encountered by gas chromatography (GC) analysts when making a split injection. It is characterized by peak response that is smallerthan expected for less-volatile compounds, and that gradually gets worse as retention time increases. The cause of this problem stems from both the sample and the injection technique. Upon injection of a sample with multiple analytes into a heated inlet, different compounds enter the gas phase at different rates. This means that a disproportionate amount of sample will be purged from the split vent.
To characterize complex samples such as natural products or peptide digests, a single chromatographic dimension cannot completely separate and identify every single compound. For such cases, comprehensive two-dimensional liquid chromatography (LC x LC) is under rapid development.