Oral Sessions (Day1, Day2, Day3)
Poster Presentations (Day1, Day2, Day3)
Oral Sessions
- Day 2, June 23（Thu.） 15:00-15:20 Room C (411 and 412)
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2C-O2-1500（2P-37） PDF
False-positive Risk Lurking in Sensitive LC-MS/MS Analysis: Influence of Trace Amounts of Impurities in "Ultrapure Water"
LC-MS/MS is a powerful analytical technique which enables highly specific determination of drugs even at the ng/L level, especially for hair samples from victims of drug-facilitated sexual assault. However, we observed a false-positive result in such analysis, where a peak of diphenhydramine (DPH, an OTC sleeping aid) constantly appeared at trace levels even in the blank tests. In this study, the cause of this phenomenon has been investigated to ensure the reliability of analysis. As a result, it has been revealed that the ultrapure water, prepared from tap water for making the mobile phases, contained DPH as an impurity at the pg/L level. DPH in the mobile phase was probably concentrated at the top of the reverse-phase LC column by the gradient program, and then was eluted with increased percentage of organic solvent in the mobile phase. DPH in the ultrapure water is probably attributed to environmental contamination with pharmaceuticals and personal care products (PPCPs). Thus, in the high-sensitivity analysis of drugs, great attention should be paid to the fact that ultrapure water, used for sample preparations or mobile phases, can contain very small amounts of PPCPs.