Study on Residues and Cleaning of Organochlorine Pesticides and Polychlorinated Biphenyls in Microsyringes

Microsyringes are being increasingly used to transfer trace liquid, but the concern of cross contamination caused by residues of organic contaminant in microsyringes is routinely overlooked. The residues and cleaning effects of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in microsyringes were systematically researched and the findings are presented in this paper. Results show that the cleaning effects are different for three brands of microsyringe. Microsyringes should be chosen according to the suitability to the intended experiment. The volume of cleaning solvent was proportional to the dilution ratio of organic contaminant, which was due to the approximate amount of contaminant in the first cleaning fluid by 4 volumes (0.1 mL, 0.2 mL, 0.5 mL and 1 mL). Moreover, the volume of cleaning solvent had a negative correlation with the amount of washout compounds. The best effect and lowest cost came from using 0.1 mL cleaning solvent. There is no difference in cleaning effects of OCPs and PCBs standard solution at the same concentration probably due to the similar physical and chemical properties of the two. Three cleaning observations were made: the residue amount of OCPs or PCBs in a 1 mL microsyringe was about 1% of the loaded amount, the amount in the first cleaning solvent was over 90% of the residues, and with the increase in cleaning times, the cleaning effect was less effective, and dilution ratio smaller. According to the above, corresponding cleaning methods can be used, according to varying concentrations of different pollutants, as far as possible to reduce organic contaminant in microsyringes and therefore reduce the cost.