absolutely, hair follicle test are as accurate as they make and even if only used once can be detected as far back as 6 months.
My ex- wife took a hair follicle test that came up positive for cocaine. She scored roughly 7800 pg/mg for the parent substance cocaine, 650 for benzoylecgonine, 3529 for cocaethylene and 220 for norcocaine. She claims she only did it once. Is that possible?