Determination of opiates in human fingernail—Comparison to hair

6-Monoacetylmorphine in keratinized matrices can be used to discriminate between heroin users and individuals exposed to other sources of morphine alkaloids. Frozen pulverization is effective in preventing 6-monoacetylmorphine hydrolysis. The main aim of this study was to develop an LC-MS/MS method for the determination of five opiates in human fingernails using a frozen pulverization preparation method and to investigate the correlation between the concentration of opiates in nail and hair samples from subjects whose urine specimens were positive for morphine. Borate buffer (500 μL; pH 9.2) was added to 20 mg of pulverized fingernail, followed by ultrasonication and liquid–liquid extraction. Analytes were analyzed on an Allure PFP propyl column by gradient elution. The mass spectrometer was operated in the positive electrospray ionization mode and multiple reactions monitoring mode. A total of 12 of 18 fingernail samples contained detectable 6-monoacetylmorphine (mean = 0.43 ng/mg, range = 0.10–1.37 ng/mg), morphine (mean = 1.74 ng/mg, range = 0.58–3.16 ng/mg) and codeine (range from <limit of quantification to 0.27 ng/mg). Similarly, 12 of 18 hair samples obtained from the same subjects were positive at the revised Society of Hair Testing cutoff level of 0.2 ng/mg. The concentrations of 6-monoacetylmorphine, acetylcodeine and codeine in hair were significantly higher than those in nails. However, the concentration of MOR in nails was significantly higher than that in hair, except for one sample. All of the ratios of 6-MAM/MOR were below 0.57. It is proposed that nails may be an alternative to hair for documenting heroin abuse.