1U. S. Department of Health and human Services. Medicare, medicaid and CLIA program: regulations implementing the clinical laboratory improvement amendment of 1988(CLIA). Final rule. Fed Regist, 1992, 57(40): 7002-7186
2Lang LM,Dalsgaard PW,Linnet K, et al. Quantitative a-nalysis of cortisol and 6(3-hydroxycortisol in urine by fullyautomated SPE and ultra-performance LC coupled withelectrospray and atmospheric pressure chemical ionization(ESCi)-TOF-MS[J]. J Sep Sci,2013,36(2) :246-251.