Detection of Methylphenidate in the Hair of Children Treated with Ritalin*

Abstract

Hair samples were collected from 17 children (7-16 years of age) who had received methylphenidate therapy on a long-term basis. The dose was 10-60 mg per day. To 20 mg of pulverized hair, phosphate buffer and internal standard (norpethidine) were added. Extraction was performed by ultrasonic treatment, followed by isolation by alkaline extraction with isohexane. Derivatization with N-Methyl-bisheptafluorobutyric amide enabled gas chromatography-mass spectrometry analysis of the perfluorobutyryl derivatives in selected ion monitoring mode. The methylphenidate concentrations lay between 0.073 and 1.1 ng/mg hair. It was noted that at higher daily doses there was a tendency toward increased concentrations in the hair, but for testing of compliance, the incorporation into hair did not occur with the required high correlation between daily dose and concentration in the hair.

Assault under the influence of methylphenidate documented by hair analysis

“…In accordance with the fact that acidic substances are incorporated to a much lesser extent than basic compounds in the hair matrix, preliminary observations [2,4] showed that ritalinic acid is absent in hair from treated subjects.…”

“…Parent from chronic exposed children [2,4], the measured concentration can be considered as very low. Segmental analyses demonstrated that only the proximal segment tested positive for MPH.…”

“…Marchei et al [2] and Sticht et al [4] have published procedures using liquid chromatography and gas chromatography coupled to mass spectrometry, respectively.…”

HPLC determination of methylphenidate and its metabolite, ritalinic acid, by high-performance liquid chromatography with peroxyoxalate chemiluminescence detection

“…Gas chromatography-mass spectrometry [10,11], HPLC-UV [12][13][14], -fluorescence (-FL) detections [15], liquid chromatography (LC-MS) [5,[7][8][9]16,17] and LC-tandem mass spectrometry (LC-MS/MS) [2,18,19] methods were widely used. Quite recently, MS detection for very low-level quantification of MPH in biological samples has been frequently used.…”

Violence under the influence of methylphenidate as determined by hair analysis

“…Marchei et al [9] published a procedure using liquid chromatography (LC) coupled to mass spectrometry (MS), which had a limit of detection of 50 pg/ mg. Sticht et al [10] used gas chromatography coupled to MS, including a derivatization step, with a limit of detection of 20 pg/mg. Because the measured concentrations in hair are as low as less than 1 ng/mg, even after chronic daily exposure [10], any method devoted to testing for MPH in hair after a single ingestion should be highly sensitive. We present here an assault case, in which the claim of a single use of MPH was supported after analysis of hair segments by ultrasensitive LC-MS-MS.…”