[Ultrasound-assisted low-density solvent dispersive liquid-liquid microextraction for the determination of eight drugs in biological samples by gas chromatography-triple quadrupole mass spectrometry].

A novel microextraction technique based on ultrasound-assisted low-density solvent dispersive liquid-liquid microextraction (UA-LDS-DLLME) has been developed for the determination of multiple drugs of abuse in biological samples by gas chromatography-triple quadrupole mass spectrometry (GC-QQQ-MS). A total of 100 µL of toluene as extraction solvent was dropped into the sample solution. Then the mixture was sonicated drastically in an ultrasonic bath for 3 min with occasional manual shaking to form a cloudy suspension. After centrifugation at 10,000 r/min for 3 min, the upper layer of low-density extractant was withdrawn and injected into the GC-QQQ-MS for analysis. The parameters affecting extraction efficiency have been investigated and optimized. Under the optimum conditions, good linearities were observed for all analytes with the correlation coefficients ranging from 0. 998 4 to 0. 999 4. The recoveries of 79.3%-100.3% with RSDs < 5.7% were obtained. The LODs (S/N = 3) were in the range from 0.05 to 0.40 µg/L. UA-LDS-DLLME technique has the advantages of less extraction time, suitable for batches of sample pretreatment simultaneously, and higher extraction efficiency. It was successfully applied to the analysis of amphetamines in real human urine samples.

Comparison of hollow fiber liquid-phase microextraction and ultrasound-assisted low-density solvent dispersive liquid-liquid microextraction for the determination of drugs of abuse in biological samples by gas chromatography-mass spectrometry.

Two microextraction techniques based on hollow fiber liquid-phase microextraction (HF-LPME) and ultrasound-assisted low-density solvent dispersive liquid-liquid microextraction (UA-LDS-DLLME) had been applied for the determination of drugs of abuse (methamphetamine, amphetamine, 3,4-methylenedioxymethamphetamine, 3,4-methylenedioxyamphetamine, methcathinone, ketamine, meperidine, and methadone) in urine and blood samples by gas chromatography-mass spectrometry. Parameters affecting extraction efficiency have been investigated and optimized for both methods. Under the optimum conditions, linearities were observed for all analytes in the range 0.0030-10 µg/ml with the correlation coefficient (R) ranging from 0.9985 to 0.9995 for HF-LPME and in the range 0.0030-10 µg/ml with the R ranging from 0.9985 to 0.9994 for DLLME. The recovery of 79.3-98.6% with RSDs of 1.2-4.5% was obtained for HF-LPME, and the recovery of 79.3-103.4% with RSDs of 2.4-5.7% was obtained for DLLME. The LODs (S/N=3) were estimated to be in the range from 0.5 to 5 ng/ml and 0.5 to 4 ng/ml, respectively. Compared with HF-LPME, the UA-LDS-DLLME technique had the advantages of less extraction time, suitability for batches of sample pretreatment simultaneously, and higher extraction efficiency, while HF-LPME has excellent sample clean-up effect, and is a robust and suitable technique for various sample matrices with better repeatability. Both methods were successfully applied to the analysis of drugs of abuse in real human blood sample.

Molecularly imprinted photonic hydrogels for fast screening of atropine in biological samples with high sensitivity.

Based on molecularly imprinted photonic hydrogels (MIPHs) that combined the colloidal-crystal with molecular imprinting technique, a novel label-free colorimetric chemosensor for convenient and fast efficient detection of atropine with high sensitivity and specificity was developed. Due to the special inverse opal arrays with a thin polymer wall in which the imprinted nanocavities of atropine moleculars distributed, the proposed MIPHs designed as water-compatible exhibited high sensitive (as low as 1 pg/mL), rapid responsive (less than 30 s) and specific detection of atropine in complex matrix. The unique three-dimensional, highly-ordered photonic hydrogels would be obviously swelling in response to the specific atropine molecular recognition process and the response would be directly transferred into visually perceptible optical signal (change in color) that could be detected by the naked eye through Bragg diffractive shifts of ordered macroporous arrays. With a broad concentration range varying from 1 pg/mL to 1 µg/mL of atropine, the distinct color changes of MIPHs almost covered the whole visible-light wavelength range from blue to red for semi-quantitative analysis. The smart chemosensor was successfully employed to determine the trace level atropine in human urine samples, providing a fast and effective alternative for semi-quantitative detection of atropine for clinical analysis and forensic investigations.

Fast screening of ketamine in biological samples based on molecularly imprinted photonic hydrogels.

A novel label-free colorimetric chemosensor was developed for handy and fast screening of ketamine with high sensitivity and specificity based on molecularly imprinted photonic hydrogels (MIPHs) that combined the colloidal-crystal with molecular imprinting technique. The unique inverse opal arrays with a thin polymer wall in which the imprinted nanocavities of ketamine moleculars distributed allowed high sensitive, quick responsive, specific detection of the target analyte, and good regenerating ability in an aqueous environment. Due to the hierarchical inverse opal structural characteristics, the specific ketamine molecular recognition process can induce obvious swelling of the MIPHs to be directly transferred into visually perceptible optical signal (change in color) which can be detected by the naked eye through Bragg diffractive shifts of ordered macroporous arrays. In order to enhance the recognition ability in aqueous environments, the MIPHs were designed as water-compatible and synthesized in a water-methanol system. The molecular recognition mechanisms were investigated. The proposed MIPHs were successfully employed to screen trace level ketamine in human urine and saliva samples, exhibiting high sensitivity, rapid response, and specificity in the complex matrix. The smart chemosensor can provide an effective alternative for fast screening of ketamine on the spot for forensic investigations.

[Analysis on opioid compounds in the hair of heroin addicts with LC-MS/MS].

OBJECTIVE: To evaluate the effects of washing process on hair samples from heroin addicts, and compare the extracting method of enzymatic digestion with homogenization of hair samples. METHODS: After washing samples for 3.15 h, a mild enzymatic digestion procedure at pH 6.6 and a buffer incubating procedure in water bath at 48 degrees C during 18h was used. The samples were pre-treated by solid phase extraction using mixed mode sorbent columns (MCX Oasis). Quantitative analysis of morphine, codeine, 6-acetylmorphine, heroin, acetylcodeine by chromatography-tandem mass spectrometry method was developed. RESULTS: Heroin accounted for 21.82% of the total equivalents of morphine. The ratio of morphine to 6-MAM in enzymatic digestion hair samples was 0.9875 and that in homogenized hair samples was 0.3948. CONCLUSION: The results suggested that the procedures were not sufficient to remove the contaminants penetrating into hair from external sources.

Small volume liquid extraction of amphetamines in saliva.

The present study introduced a procedure of small volume liquid extraction of amphetamines, including amphetamine (AM); methamphetamine (MA); 3,4-methylenedioxyamphetamine (MDA); 3,4-methylenemethamphtamine (MDMA), in saliva. Extraction efficiencies were compared between the conventional volume liquid phase extraction (LPE) and the small volume one, in which <100 microL solvent was used instead of several milliliters in LPE. Conditions such as types and volumes of organic solvent used in the extraction and concentrations of target analytes in aqueous samples were examined. Results showed that small volume liquid extraction had an enrichment effect on the analytes. After extraction, the organic phase was either directly drawn out for GC analysis, or partially transferred to another vial for derivatization. Detection limits were less than 5 ng/mL in saliva using GC/MS-SIM after derivatization. RSD (of peak area ratios) was less than 15% at all drug concentrations. The method was used in the analyses of saliva collected from amphetamine abusers, and was proven to be practical for detecting trace amounts of amphetamines in saliva.

Determination of amphetamines in hair by GC/MS after small-volume liquid extraction and microwave derivatization.

We report here on the results of a procedure for the determination of amphetamine drugs in hair. The procedure is simple and sensitive. The results from the procedure using small-volume extraction matches perfectly with those either from using the derivatization method or selected ion monitoring (SIM) detection. We validated our method using four different amine drugs, including amphetamine, methamphetamine, methylenedioxy-amphetamine and methylenedioxy-methamphetamine. The detection limit for these drugs is about 50 +/- 7.5 pg/mg in hair and the intra-day and inter-day reproducibility are within 15% at most drug concentrations. Moreover, we also showed the utility of the procedure in analyses of authentic hair samples taken from amphetamine abusers, and demonstrated that the method meets the requirement for the analysis of a trace amounts of amphetamines in human hair.

[Determination of amphetamines in human hair using dynamic liquid-phase microextraction and gas chromatography/selected ion monitoring-mass spectrometry after microwave derivatization].

Human hair is an important specimen for drug abuse analysis owing to its easy collection, long surveillance time window and good correlation between the "degree of addiction" and actual drug concentration. A simple method for determination of 4 amphetamines in human hair was developed. The hair was digested under basic condition, and the drugs in it were extracted using microvolume of chloroform. The organic layer was then transferred into another tube to be derivatized with N-methyl-bis (trifluoroacetamide) (MBTFA) by microwave heating. Finally the reacted solution was detected by gas chromatography/selected ion monitoring-mass spectrometry (GC/SIM-MS) directly. 2-Methyl-phenyl ethylamine was used as an internal standard. Good linearities were obtained for 4 amphetamines with correlation coefficients better than 0.996. The limits of detection, based on a signal-to-noise ratio (S/N) of 3:1, were all about 50 pg/mg for amphetamine (AM) , methamphetamine (MAM), methylenedioxy-amphetamine (MDA), and methylenedioxy-methamphetamine (MDMA) in hair. The reproducibility of the method was satisfactory, with the relative standard deviations of 6.0% for AM, 13.9% for MAM, 10.2% for MDA and 9.2% for MDMA. Some real hair from the drug abusers was analyzed with this method. The minimal hair is less than 5 mg (about 20 cm). The method is highly sensitive, easy to operate, time-saving and economic, which can be used for trace analysis of amphetamines in human hair.

Analysis of amphetamine, methamphetamine and methylenedioxy-methamphetamine by micellar capillary electrophoresis using cation-selective exhaustive injection.

Cation-selective exhaustive injection (CSEI) is used as an on-line concentration method for the high-sensitivity analysis of illicit amphetamines using CE. Optimum conditions for the determination of amphetamine, methamphetamine and methylenedioxy-methamphetamine were investigated. Sodium dodecyl sulfate (25 mM) in 100 mM phosphate buffer (pH 2.9) with 20% methanol as organic additive was used as the background electrolyte for CE separation. The LOD, based on an S/N of 3:1, was about 0.01 microg/mL using normal capillary micellar electrokinetic chromatography, while by using CSEI in combination with micellar sweeping the sensitivity increased up to 1000-fold with the LOD lower than 50 pg/mL. The reproducibility of CSEI combined with micellar sweeping for analyzing amphetamines was satisfactory (relative standard deviation around 10% by using area ratios against an internal standard). This method is highly sensitive and can be used to analyze trace amount amphetamines in human hair.