Rapid analysis of methamphetamine in hair by
#0183;#32;The tube was capped and shaken vertically for 5 min at 1500 strokes/min using an Automill automatic pulverizer (Tokken). After a brief centrifugation, the bullet was removed using tweezers and the suspension was filtered using a centrifugal filter unit fitted with a polyvinylidene fluoride microporous membrane (Ultrafree MC, Millipore, Billerica, MA).