MALDI‐TOF and MALDI‐FTICR imaging mass spectrometry of methamphetamine incorporated into hair

Abstract

A new approach is described for imaging mass spectrometry (IMS) of methamphetamine (MA) incorporated into human hair using matrix-assisted laser desorption/ionization (MALDI)-time-of-flight (TOF) and MALDI-Fourier transform ion cyclotron resonance (FTICR). A longitudinal section of a lengthwise manually-cut single human hair shaft from a chronic MA user was directly analyzed by MALDI-TOF-IMS after deposited with α-Cyano-4-hydroxycinnamic acid matrix. A barcode-like image, which was most probably generated with repeated intakes of MA, was for the first time obtained by monitoring MA-specific product ion in the selected reaction monitoring mode. Laser beam scan lengthwise-cut hair shafts gave only poor mass spectra of MA, probably due to the loss of MA and/or the thermal denaturation of hair. The identity of MA detected in hair was further confirmed by MALDI-FTICR mass spectrometry. A combination with ultra-high resolution mass spectrometry by FTICR provided indisputable identification of MA. The MALDI-FTICR-IMS of another hair shaft from the same MA user also provided a barcode-like image by monitoring the protonated molecule of MA with ultra-high resolution. The two barcode-like images exhibited a close resemblance. Thus, MALDI-IMS can offer a new perspective: 'imaging hair analyses for drugs'.

Sample preparation for mass spectrometry imaging: Small mistakes can lead to big consequences

“…Similar transfer methods are employed for stretched sample processing to increase physical spatial dimension of the tissue [72,73] enabling higher spatial resolution to be achieved by pulling apart individual cells. Some mass spectrometers require the tissue to be on a conductive surface so adhesive conductive tape can be used [74]. Thaw-mounting, whereby the frozen tissue is transferred by gently touching it to a warm surface, is most common when standard small organs are sectioned.…”

Applications of MALDI Mass Spectrometry in Clinical Chemistry

“…MALDI-TOF MS has also been used for the direct analysis of human hair. Initial applications have focused on using MALDI-TOF MS to detect drugs such as methoxyphenamine (43 ), cocaine (44 ), and ket- The spectra show the dominating Hb 1+ and Hb 2+ species (used as calibrants). Other peaks can be assigned to hemoglobin marked 1 through 6 as follows: 1, ␣Hb missing C terminal arginine; 2, sinapinic acid matrix adducts to ␣Hb; 3, m/z 2+ species of the ␣Hb-␤Hb dimer; 4, ␤Hb missing C-terminal histidine; 5, sinapinic acid matrix adducts to ␤Hb; 6, glutathione modification to ␤Hb.…”

Conductive carbon tape used for support and mounting of both whole animal and fragile heat-treated tissue sections for MALDI MS imaging and quantitation

“…Again, such a method is less than ideal as it requires the sample to be transferred between surfaces and is not suitable for analysis by mass spectrometers that require the sample to be adhered to a conductive surface. Finally, a recently reported use of MSI has been the analysis of methamphetamine in a single strand of hair and is performed by attaching the sample using double sided adhesive carbon tape to MALDI compatible targets [22]. Such an approach enabled the analysis of the hair using both MALDI TOF MS and MALDI FT-ICR MS.…”