Analytical methods for abused drugs in hair and their applications

Hair has been focused on for its usability as an alternative biological specimen to blood and urine for determining drugs of abuse in fields such as forensic and toxicological sciences because hair can be used to elucidate the long intake history of abused drugs compared with blood and urine. Hair analysis consists of several pretreatment steps, such as washing out contaminates from hair, extraction of target compounds from hair, and cleanup for instrumental analysis. Each step includes characteristic and independent features for the class of drugs, e.g., stimulants, narcotics, cannabis, and other medicaments. In this review, recently developed methods to determine drugs of abuse are summarized, and the pretreatment steps as well as the sensitivity and applicability are critically discussed.     

Peroxyoxalate chemiluminescence detection for the highly sensitive determination of fluorescence-labeled chlorpheniramine with Suzuki coupling reaction

A sensitive and selective high performance liquid chromatography-peroxyoxalate chemiluminescence (PO-CL) method has been developed for the simultaneous determination of chlorpheniramine (CPA) and monodesmethyl chlorpheniramine (MDCPA) in human serum. The method combines fluorescent labeling with 4-(4,5-diphenyl-1H-imidazole-2-yl)phenyl boronic acid using Suzuki coupling reaction with PO-CL detection. CPA and MDCPA were extracted from human serum by liquid–liquid extraction with n-hexane. Excess labeling reagent, which interfered with trace level determination of analytes, was removed by solid-phase extraction using a C18 cartridge. Separation of derivatives of both analytes was achieved isocratically on a silica column with a mixture of acetonitrile and 60 mM imidazole-HNO₃ buffer (pH 7.2; 85:15, v/v) containing 0.015% triethylamine. The proposed method exhibited a good linearity with a correlation coefficient of 0.999 for CPA and MDCPA within the concentration range of 0.5–100 ng/mL. The limits of detection (S/N = 3) were 0.14 and 0.16 ng/mL for CPA and MDCPA, respectively. Using the proposed method, CPA could be selectively determined in human serum after oral administration.     

In vivo isotropic 3D diffusion tensor mapping of the rat brain using diffusion-weighted 3D MP-RAGE MRI

The purpose of this study was to examine the potential of diffusion-weighted (DW) three-dimensional (3D) MP-RAGE MRI for diffusion-tensor mapping of the rat brain in vivo. A DW-3D-MP-RAGE (3D-DWI) sequence was implemented at 2.0 T using six gradient orientations and a b value of 1000 s/mm2. In this sequence, the preparation sequence with a "90 degrees RF-motion proving gradient (MPG): MPG-180 degrees RF-MPG-90 degrees RF" pulse train (DW driven equilibrium Fourier transform) was used to sensitize the magnetization to diffusion. A centric k-space acquisition order was necessary to minimize saturation effects (T1 contamination) from tissues with short relaxation time. The image matrix was 128x128x128 (interpolated from 64x64x64 acquisitions), which resulted in small isotropic DW image data (voxel size: 0.273x0.273x0.273 mm3). Moreover, 3D-DWI-derived maps of the fractional anisotropy (FA), relative anisotropy (RA) and main-diffusion direction were completely free of susceptibility-induced signal losses and geometric distortions. Two well-known commissural fibers, the corpus callosum and anterior commissure, were indicated and shown to be in agreement with the locations of these known stereotaxic atlases. The experiment took 45 min, and shorter times should be possible in clinical application. The 3D-DWI sequence allows for in vivo 3D diffusion-tensor mapping of the rat brain without motion artifacts and susceptibility to distortion.     

An ultramicro assay for human plasma prekallikrein activity by phosphorimetry

A highly sensitive method for the phosphorimetric assay of prekallikrein in human blood plasma is described. Prekallikrein is converted to kallikrein (active form) by reaction at 0°C with actin. p-Nitroaniline, formed enzymatically from H-d-prolyl-l-phenylalanyl-l-arginyl-p-nitroanilide, is extracted with ether and determined phosphorimetrically in a mixture of ether and ethanol. The method is precise and highly sensitive, requiring as little as 0.25 μl of human blood plasma. The limit of detection for p-nitroaniline formed enzymatically is 5 pmol.     

Phosphorimetric microassay for succinyltrialanyl-p-nitroanilide-hydrolyzing enzyme activity in human serum

A phosphorimetric assay of succinyltrialanyl-p-nitroanilide-hydrolyzing enzyme activity in human serum is described. p-Nitroaniline formed enzymatically is extracted with ether and determined phosphorimetrically in an ether/ethanol glass. The method is precise and very sensitive, requiring as little as 5 μl of human serum. The limit of detection is 10 pmol.     

Optical fiber sensor for the measurement of electric field intensity and voltage (OPSEF)

An optical fiber sensor for measuring high electric field intensity and voltage, which utilizes the electro-optic effect of bismuth silicone oxide single crystal, has been developed successfully, and the fundamental characteristics have been evaluated. The electric field intensity distribution inside the coaxial electrodes has been measured with this sensor. The measured results are in agreement with the theoretical values.     

Preferential segregation of dopants in μc-Si:H

Electronic and structural properties of heavily B-doped μc-Si:H films prepared by rf glow discharge technique have been studied by Raman scattering, IR absorption, SIMS and conductivity measurements. It is found that boron atoms in μc-Si:H tend to segregate in the amorphous tissue. The remarkable difference in doping efficiency between B- and P-doped μc-Si:H was interpreted in terms of the different degree of dopant segregation in the amorphous phase.