[Research progress on chiral separation of amphetamines, ketamine, cathinones].

Enantiomers are ubiquitous in nature, and they are especially important in the field of pharmaceutical chemistry. Although the enantiomers of chiral drugs have identical chemical structures, they differ notably in their pharmacological, toxicological, pharmacokinetic, metabolic, and other biological activities. The same is true for amphetamines, ketamine, and cathinones, as the chiral separation of these three drugs is representative of drugs. Gas chromatography (GC), high performance liquid chromatography (HPLC), and capillary electrophoresis (CE) are widely used for the chiral separation of these three kinds of drugs. There are some similarities among the three methods for the chiral separation of amphetamines, ketamine, and cathinones: n-trifluoroacetyl-L-prolinyl chloride and (+)R-α-methoxy-α-trifluoromethylphenylacetic acid are the two typical chiral derivatization reagents used in GC. In HPLC, three kinds of chiral stationary phases are used: proteins, polysaccharides, and macrocyclic antibiotics. Cyclodextrin and its derivatives are most commonly used in CE. However, these three methods have inherent shortcomings. In the case of GC, impurities produced during chiral derivatization may interfere with the analysis, and high reaction temperatures affect the efficiency of chiral separation. HPLC has limited application scope and is expensive. In CE, there has no established process to determine the appropriate chiral selector. In recent years, research into application of the chiral separation of the above-mentioned three kinds of drugs has its own characteristics in forensic toxicology. The chiral separation of amphetamine drugs is mostly used to infer the prototype and synthesis route of drugs on the market. The chiral separation of ketamine involves a variety of biological samples. For cathinones, chiral separation methods emphasize their wide applicability. In this review, 66 reports published in professional local and overseas magazines during the past decade are collated. The characteristics of the enantiomers of amphetamines, ketamine, and cathinones as well as the mechanism of chiral recognition are briefly introduced. The commonness of the research and the application of chiral separation in forensic toxicology are reviewed. This paper proposes that the chiral separation of drugs can be further investigated from the following three aspects: 1) the use of computer technology to establish a molecular model for exploring the mechanism of chiral recognition; 2) developing new technologies for chiral separation and carrying out commercial research on the supercritical fluid method; 3) applying chiral separation to judicial practice, pharmaceutical research and development, and other practical fields.

Targeted mass spectrometry of ketamine and its metabolites cis-6-hydroxynorketamine and norketamine in human blood serum.

Ketamine (KET) was originally developed as an anesthetic agent but has also attracted attention for further clinical applications such as medical treatment of depression or pain. The use of KET induces dissociation and emergence delirium. Due to these effects, KET has a high potential for abuse. In order to investigate metabolization of KET or to confirm misuse of KET, highly sensitive analytical methods that cover KET and its metabolites are necessary. A new analytical approach for simultaneous analysis of KET and its metabolites cis-6-hydroxynorketamine (HNK) and norketamine (NK) was established. The compounds were extracted from human blood serum by ultrafiltration and solid phase extraction with subsequent vacuum evaporation. The compounds were analyzed by non-enantioselective ultra-high performance micro-flow liquid chromatography (Waters ACQUITY UPLC® M-Class HSS T3 column, 0.1% formic acid and acetonitrile with 0.1% formic acid, 14 µL/min flow rate) coupled with tandem mass spectrometry in positive scheduled multiple reaction monitoring mode. Validation parameters such as linearity, precision, recovery, accuracy, stability, limit of detection (LOD), and limit of quantification (LOQ) were proven. LOD for KET and NK was 0.08 ng/mL and LOQ were 0.5 ng/mL and 0.6 ng/mL, respectively. For HNK, LOD was 0.1 ng/mL and LOQ 0.8 ng/mL. The method was then successfully applied to quantify KET, HNK, and NK in blood serum samples from subjects who received KET intravenously. A novel method for the simultaneous analysis of KET, NK, and HNK was established. This new method could now be used for clinical trials investigating KET and its metabolites HNK and NK or for forensic analysis in order to confirm KET abuse.

Sensitive detection of ketamine with an electrochemical sensor based on UV-induced polymerized molecularly imprinted membranes at graphene and MOFs modified electrode.

Ketamine is one of the most widely abused drugs in the world and poses a serious threat to human health and social stability; therefore, the ability to accurately monitor the substance in real-time is necessary. However, several problems still exists towards this goal, such as the generally low concentration of the target molecules disturbed in the complex samples that undergo analysis during criminal investigations. In this work, the sensitive and selective detection of ketamine was accomplished by molecularly imprinted electrochemical sensor. The molecularly imprinted membrane as a biomimetic recognition element was fabricated by the UV-induced polymerization of methacrylic acid (MAA) and ethylene glycol dimethacrylate (EGDMA) on a metal-organic framework/graphene nanocomposite (MOFs@G) modified screen-printed electrode. The screen printed electrode (SPE) provided good adhesion for the formation of the imprinted membranes and increased the stability of the sensor. The morphology and performance of the imprinted films were characterized in detail by scanning electron microscopy (SEM), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and differential pulse voltammetry (DPV). The experimental results demonstrated that the imprinted sensor had excellent sensitivity, selectivity, and long-term stability. It offered a low detection limit (4.0 × 10-11 mol L-1) and had a dynamic range from 1.0 × 10-10 mol L-1 to 4.0 × 10-5 mol L-1. Furthermore, the established method was successfully applied for the determination of ketamine in urine and saliva samples.

Subcritical Fluid Chromatography at Sub-Ambient Temperatures for the Chiral Resolution of Ketamine Metabolites with Rapid-Onset Antidepressant Effects.

Chiral metabolites of ketamine exerting rapid-onset yet sustained antidepressant effects may be marketed directly in the future, but require chemo- and enantio-selective chromatographic methods for quality assurance and control. The chromatographic behavior of S-/R-ketamine, S-/R-norketamine, S-/R-dehydronorketamine, and (2R,6R)-/(2S,6S)-hydroxynorketamine in supercritical fluid chromatography (SFC) was investigated computationally and experimentally with the aim of identifying problematic pairs of enantiomers and parameters for chiral resolution. Retention on three different polysaccharide-based chiral stationary phases (Lux Amylose-2, i-Amylose-3, and i-Cellulose-5) provided new information on the significance of halogen atoms as halogen bond donors and hydrogen bond acceptors for enantioselectivity, which could be corroborated in silico by molecular docking studies. Modifiers inversely affected enantioselectivity and retention. Methanol yielded lower run times but superior chiral resolution compared to 2-propanol. Lower temperatures than those conventionally screened did not impair phase homogeneity but improved enantioresolution, at no cost to reproducibility. Thus, sub-ambient temperature subcritical fluid chromatography (SubFC), essentially low-temperature HPLC with subcritical CO2, was applied. The optimization of the SubFC method facilitated the chiral separation of ketamine and its metabolites, which was applied in combination with direct injection and online supercritical fluid extraction to determine the purity of pharmaceutical ketamine formulations for proof of concept.

Development and validation of an HPLC-MS/MS method for the detection of ketamine in Calliphora vomitoria (L.) (Diptera: Calliphoridae).

Entomotoxicology is a branch of forensic entomology that studies the detection of drugs or other toxic substances from insects developing on the decomposing tissues of a human corpse or animal carcass. Entomotoxicology also investigates the effects of these substances on insect development, survival and morphology to provide an estimation of the minimum time since death. Ketamine is a medication mainly used for starting and maintaining anesthesia. In recent years ketamine has also been used as a recreational drug, and occasionally as a sedating drug to facilitate sexual assault. In both activities, it has resulted in several deaths. Furthermore, ketamine has been also implicated in suspicious deaths of animals. The present research describes for the first time the development and validation of an analytical method suited to detect ketamine in larvae, pupae, empty puparia, and adults of Calliphora vomitoria L. (Diptera: Calliphoridae), using liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). This research also considers the effects of ketamine on the survival, developmental rate and morphology (length and width of larvae and pupae) of C. vomitoria. The larvae were reared on liver substrates homogeneously spiked with ketamine concentrations consistent with those found in humans after recreational use (300 ng/mg) or allegedly indicated as capable of causing death in either humans or animals (600 ng/mg). The results demonstrated that (a) HPLC-MS/MS method is applicable to ketamine detection in C. vomitoria immatures, not adults; (b) the presence of ketamine at either concentration in the food substrate significantly delays the developmental time to pupal and adult instar; (d) the survival of C. vomitoria is negatively affected by the presence of ketamine in the substrate; (e) the length and width of larvae and pupae exposed to either ketamine concentration were significantly larger than the control samples.

Separation of hydroxynorketamine stereoisomers using capillary electrophoresis with sulfated ß-cyclodextrin and highly sulfated γ-cyclodextrin.

The racemic N-methyl-d-aspartate receptor antagonist ketamine is used in anesthesia, analgesia and the treatment of depressive disorders. It is known that interactions of hydroxylated norketamine metabolites and 5,6-dehydronorketamine (DHNK) with the α7 -nicotinic acetylcholine receptor and the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor are responsible for the antidepressive effects. Ketamine and its first metabolite norketamine are not active on these receptors. As stereoselectivity plays a role in ketamine metabolism, a cationic capillary electrophoresis based method capable of resolving and analyzing the stereoisomers of four hydroxylated norketamine metabolites, norketamine and DHNK was developed. The assay is based on liquid/liquid extraction of the analytes from the biological matrix, electrokinetic sample injection across a buffer plug and analysis of the stereoisomers in a phosphate background electrolyte (BGE) at pH 3 comprising a mixture of sulfated ß-cyclodextrin (5 mg/mL) and highly sulfated γ-cyclodextrin (0.1%). The method was used to analyze samples of an in vitro study in which ketamine was incubated with equine liver microsomes and in plasma samples of dogs and horses that were collected after an i.v. bolus injection of racemic ketamine.

Physicochemical stability of ternary admixtures of butorphanol, ketamine, and droperidol in polyolefin bags for patient-controlled analgesia use.

BACKGROUND: Delivery of drug admixtures by intravenous patient-controlled analgesia is a common practice for the management of postoperative pain; however, analytical confirmation of the compatibility and stability of butorphanol tartrate, ketamine hydrochloride, and droperidol combined in ternary admixtures is not available. METHODS: Butorphanol tartrate, ketamine hydrochloride, and droperidol have been examined for compatibility and stability when combined with 0.9% sodium chloride injection stored at 4°C and 25°C with light protection for a total of 14 days. Concentrations were 0.067 mg/mL, 1.33 mg/mL, and 0.033 mg/mL for butorphanol tartrate, ketamine hydrochloride, and droperidol, respectively. Drug concentrations were determined using high-performance liquid chromatographic analysis. RESULTS: All three drugs were very stable (>97%) at 4°C and 25°C for 14 days. The ternary admixtures were initially clear and colorless throughout the observation period, and the pH value did not change significantly. CONCLUSION: The results confirm that the ternary admixture of butorphanol tartrate 0.067 mg/mL, ketamine hydrochloride 1.33 mg/mL, and droperidol 0.033 mg/mL in 0.9% sodium chloride injection were stable for 14 days when stored in polyolefin bags at 4°C and 25°C and protected from light.

Chiral separation and determination of ketamine and norketamine in hair by capillary electrophoresis.

Ketamine, traditionally available as racemic mixture, has recently become available in the form of the single S-enantiomer, due to its higher anaesthetic potency associated with faster recovery times. The different pharmaceutical forms and the different pharmacodynamics of the two enantiomers imply the need for a chiral method, since most available analytical methods for biological matrices are not enantioselective. The method herein showed consists of simple capillary zone electrophoresis (CZE) for the chiral separation of ketamine and its major metabolite, norketamine, in hair specimens. After liquid-liquid extraction, the samples were electrokinetically injected and analysed in CE (running buffer: 15mM Tris phosphate pH 2.5, containing HS-γ-CDs, 0.1%, w/v). A complete separation of both racemic ketamine and norketamine in the respective enantiomers was obtained in less than 10minutes. Limit of detection (LOD) and limit of quantification (LOQ) were 0.08ng/mg and 0.25ng/mg, respectively. Percent recovery varied from 49% to 91% for all four enantiomers. Matrix effect on spiked hair samples demonstrated values ranging from 63% to 119%. Linearity was estimated using a calibration curve consisting of five concentration levels for each enantiomer (0.5-8.0ng/mg); the regression coefficients (R(2)) of weighted (1/x(2)) linear regression were all >0.988. The method is suitable for the analysis of real-world hair samples in order to investigate ketamine chronic abuse and to discriminate between the type of abused drug, either single enantiomer or racemic drug.

Simultaneous analysis method for GHB, ketamine, norketamine, phenobarbital, thiopental, zolpidem, zopiclone and phenytoin in urine, using C18 poroshell column.

Date-rape drugs have the potential to be used in drug-facilitated sexual assault, organ theft and property theft. Since they are colorless, tasteless and odorless, victims can drink without noticing, when added to the beverages. These drugs must be detected in time, before they are cleared up from the biofluids. A simultaneous extraction and determination method in urine for GHB, ketamine, norketamine, phenobarbital, thiopental, zolpidem, zopiclone and phenytoin (an anticonvulsant and antiepileptic drug) with LC-MS/MS was developed for the first time with analytically acceptable recoveries and validated. A 4 steps liquid-liquid extraction was applied, using only 1.000mL urine. A new age commercial C18 poroshell column with high column efficiency was used for LC-MS/MS analysis with a fast isocratic elution as 5.5min. A new MS transition were introduced for barbital. 222.7>179.8 with the effect of acetonitrile. Recoveries (%) were between 80.98-99.27 for all analytes, except for GHB which was 71.46. LOD and LOQ values were found in the ranges of 0.59-49.50 and 9.20-80.80ngmL(-1) for all the analytes (except for GHB:3.44 and 6.00µgmL(-1)). HorRat values calculated (between 0.25-1.21), revealed that the inter-day and interanalist precisions (RSD%≤14.54%) acceptable. The simultaneous extraction and determination of these 8 analytes in urine is challenging because of the difficulty arising from the different chemical properties of some. Since the procedure can extract drugs from a wide range of polarity and pKa, it increases the window of detection. Group representatives from barbiturates, z-drugs, ketamine, phenytoin and polar acidic drugs (GHB) have been successfully analyzed in this study with low detection limits. The method is important from the point of determining the combined or single use of these drugs in crimes and finding out the reasons of deaths related to these drugs.

Optimization of an optical inspection system based on the Taguchi method for quantitative analysis of point-of-care testing.

This study presents an optical inspection system for detecting a commercial point-of-care testing product and a new detection model covering from qualitative to quantitative analysis. Human chorionic gonadotropin (hCG) strips (cut-off value of the hCG commercial product is 25 mIU/mL) were the detection target in our study. We used a complementary metal-oxide semiconductor (CMOS) sensor to detect the colors of the test line and control line in the specific strips and to reduce the observation errors by the naked eye. To achieve better linearity between the grayscale and the concentration, and to decrease the standard deviation (increase the signal to noise ratio, S/N), the Taguchi method was used to find the optimal parameters for the optical inspection system. The pregnancy test used the principles of the lateral flow immunoassay, and the colors of the test and control line were caused by the gold nanoparticles. Because of the sandwich immunoassay model, the color of the gold nanoparticles in the test line was darkened by increasing the hCG concentration. As the results reveal, the S/N increased from 43.48 dB to 53.38 dB, and the hCG concentration detection increased from 6.25 to 50 mIU/mL with a standard deviation of less than 10%. With the optimal parameters to decrease the detection limit and to increase the linearity determined by the Taguchi method, the optical inspection system can be applied to various commercial rapid tests for the detection of ketamine, troponin I, and fatty acid binding protein (FABP).

Liquid-phase microextraction based on two immiscible organic solvents followed by gas chromatography with mass spectrometry as an efficient method for the preconcentration and determination of cocaine, ketamine, and lidocaine in human urine samples.

A new type of liquid-phase microextraction based on two immiscible organic solvents was optimized and validated for the quantification of lidocaine, ketamine, and cocaine in human urine samples. A hollow-fiber based microextraction technique followed by gas chromatography coupled with mass spectrometry detection was used to reduce matrix interferences and improve limits of detection. The analytes were extracted from aqueous sample with pH 11.0, into a thin layer of organic solvent (n-dodecane) sustained in the pores of a hollow fiber, and then into a second organic acceptor (acetonitrile) located inside the lumen of the hollow fiber. With the application of optimized values, good linearity was obtained in the range of 1-500 µg/L for lidocaine and ketamine and 2-500 µg/L for cocaine with the determination coefficient values (r(2) ) >0.9943. The preconcentration factors and limits of detection (S/N > 3) were 250-350 and 0.01-0.05 µg/L, respectively. Intra and interassay precision values were <7.3 and 9.3%, respectively. The method was successfully applied for the determination and quantification of target analytes in human urine samples.

Development of a method for analysis of ketamine and norketamine enantiomers in equine brain and cerebrospinal fluid by capillary electrophoresis.

Ketamine and norketamine are being transported across the blood brain barrier and are also entering from blood into cerebrospinal fluid (CSF). Enantioselective distributions of these compounds in brain and CSF have never been determined. The enantioselective CE based assay previously developed for equine plasma was adapted to the analysis of these compounds in equine brain via use of an acidic pre-extraction of interferences prior to liquid/liquid extraction at alkaline pH. CSF can be treated as plasma. With 100 mg of brain tissue and 0.5 mL of CSF or plasma, assay conditions for up to 30 nmol/g and 6 µM, respectively, of each enantiomer with LOQs of 0.5 nmol/g and 0.1 µM, respectively, were established and the assays were applied to equine samples. CSF and plasma samples analyzed stemmed from anesthetized patient horses and brain, CSF and plasma were obtained from anesthetized horses that were euthanized with an overdose of pentobarbital. Data obtained indicate that ketamine and norketamine enantiomers are penetrating into brain and CSF with those of ketamine being more favorably transported than norketamine, whereas metabolites of norketamine are hindered. More work is required to properly investigate possible stereoselectivities of the ketamine metabolism and transport of metabolites from blood into brain tissue and CSF.

A high-throughput method based on microwave-assisted extraction and liquid chromatography-tandem mass spectrometry for simultaneous analysis of amphetamines, ketamine, opiates, and their metabolites in hair.

A total sample-preparation and analysis time of 50 min is required for the high-throughput method of hair analysis proposed in this paper. The method is applicable to analysis of drugs commonly used in Asia, and their metabolites--methamphetamine (MA), amphetamine (AMP), methylenedioxymethamphetamine (MDMA), methylenedioxyamphetamine (MDA), ketamine (K), norketamine (NK), dehydronorketamine (DHNK), 6-acetylmorphine (6-AM), morphine (MOR), and codeine (COD). Cut and weighed hair (10 mg) was incubated for 3 min with methanol-trifluoroacetic acid (TFA) during microwave-assisted extraction (MAE) at 700 W. The incubation solution was evaporated, the residue was reconstituted in deionized water-methanol, 99:1 (v/v), and 20 µL was injected on to a core-shell column (50 × 4.6 mm, 2.6 µm particle size) for liquid chromatographic-tandem mass spectrometric (LC-MS-MS) analysis. Gradient elution separation was performed in 8 min at a flow rate of 1 mL min(-1). No signal interfering with any of the analytes was found in fourteen blank hair samples from different sources. The limits of detection and quantification were 0.5 pg mg(-1) and 2.0 pg mg(-1), respectively, for MA, AMP, MDMA, MDA, K, NK, and DHNK, and 2.0 pg mg(-1) and 5.0 pg mg(-1), respectively, for 6-AM, MOR and COD. The linear range was between the LOQ and 1000 pg mg(-1), and the correlation coefficients were all greater than 0.999. Investigation of matrix effects revealed that all the analytes were suppressed by less than 20% and the standard deviation (SD) was always less than 7%. Recovery was always greater than 90% and the SD for each compound was less than 6%. Precision and accuracy for each analyte were within 15%. Eight authentic hair specimens from known drug abusers were successfully analyzed. Compared with traditional overnight incubation methods, the rapid 3-min extraction time achieved similar or greater extraction yields. Sample preparation by MAE was a reliable procedure for extraction of the analytes from hair but substantially simpler and faster than other methods.

Electromembrane extraction of stimulating drugs from undiluted whole blood.

For the first time, electromembrane extraction (EME) of six basic drugs of abuse from undiluted whole blood and post mortem blood in a totally stagnant system is reported. Cathinone, methamphetamine, 3,4-methylenedioxy-amphetamine (MDA), 3,4-methylenedioxy-methamphet-amine (MDMA), ketamine and 2,5-dimethoxy-4-iodoamphetamine (DOI) were extracted from the whole blood sample, through a supported liquid membrane (SLM) consisting of 1-ethyl-2-nitrobenzene (ENB) immobilized in the pores of a hollow fiber, and into an aqueous acceptor solution inside the lumen of the hollow fiber. The SLM acts as a barrier with efficient exclusion of all macromolecules and acidic substances in the sample. Due to the application of the electrical field, only the cationic compounds of interest are extracted efficiently across the membrane, thus providing extremely clean extracts for analysis with liquid chromatography-mass spectrometry, LC-MS. Recoveries in the range 10-30% were obtained from 80 µl whole blood within 5 min extraction time and an applied voltage of 15V across the SLM. The optimized technique was tested on real forensic whole blood samples taken from three forensic autopsy cases and on five forensic whole blood samples from living persons. The results were in agreement with the analysis using standard sample preparation methods (liquid-liquid extraction) performed on the same samples by Norwegian Institute of Public Health (NIPH), Division of Forensic Toxicology and Drug Abuse Research. Evaluation data were acceptable, with limit of detections (LODs) in the range 40-2610 pg/mL, well below concentrations associated with drug abuse; linearites in the range between 10 and 250 ng/mL with r(2) values above 0.9939, and with repeatability (RSD) of 7-32%.

Detecting ketamine in beverage residues: Application in date rape detection.

Ketamine can be used to facilitate date-rape when unknowingly spiked into a victim's beverage. If a biological sample is not available from the victim, the beverage container might be the only remaining source of forensic evidence. We present a rapid, simple analysis method for the detection of ketamine in wet or dry beverage residues based on liquid chromatography-mass spectrometry (LC-MS). Wet residues consist of the final few drops (<1 ml) in a container while dry residues are the remains once all liquid has evaporated. By using LC-MS, which readily handles aqueous samples, often no derivatization or sample extraction is needed, thus reducing analysis time and lab technician involvement. Tandem mass spectrometry (MS/MS) provides an enhancement in both selectivity and sensitivity. We have studied a range of beverages and determined limits of detection between 1.2 × 10-3 and 1.3 × 10-4 mg/ml, compared to 0.21-0.85 mg/ml used in most date-rape scenarios. This paper represents the first published report of using LC-MS/MS for the analysis of beverage residues for the presence of a date-rape drug. This method could replace the current gas chromatography-mass spectrometry (GC-MS) methods and provide a faster, more selective method for the analysis of date-rape drugs, requiring virtually no sample preparation.

Determination of eight illegal drugs in human urine by combination of magnetic solid-phase extraction with capillary zone electrophoresis.

Using magnetite/silica/poly(methacrylic acid-co-ethylene glycol dimethacrylate) (Fe(3)O(4)/SiO(2)/poly(MAA-co-EDMA)) magnetic microspheres, a rapid and high-throughput magnetic solid-phase extraction coupled with capillary zone electrophoresis (MSPE-CZE) method was developed for the determination of illegal drugs (ketamine, amphetamines, opiates, and metabolites). The MSPE of target analytes could be completed within 2 min, and the eight target analytes could be baseline separated within 15 min by CZE with 30 mM phosphate buffer solution (PBS, pH 2.0) containing 15% v/v ACN as background electrolyte. Furthermore, hydrodynamic injection with field-amplified sample stacking (FASS) was employed to enhance the sensitivity of this MSPE-CZE method. Under such optimal conditions, the limits of detection for the eight target analytes ranged from 0.015 to 0.105 µg/mL. The application feasibility of MSPE-CZE in illegal drugs monitoring was demonstrated by analyzing urine samples, and the recoveries of target drugs for the spiked sample ranging from 85.4 to 110.1%. The method reproducibility was tested by evaluating the intra- and interday precisions, and relative standard deviations of <10.3 and 12.4%, respectively, were obtained. To increase throughput of the analysis, a home-made MSPE array that has potential application to the treatment of 96 samples simultaneously was used.

Extraction of ketamine from urine using a miniature silica monolithic cartridge followed by quantification with liquid chromatography tandem mass spectrometry (LC-MS/MS).

The high surface area monolith with reactive hydroxyl group on its surface enables it to function as a miniature solid-phase extraction (SPE) cartridge in size of 1 cm in diameter and 0.5 cm in length. The prepared silica monolith was characterized by Brunauer-Emmett-Teller method, scanning electron microscopy, X-ray diffraction and Fourier transform infrared (FTIR) spectroscopy. Ketamine was selected as model analyte to validate the extraction efficiency of the prepared cartridge. The extracted ketamine from urine sample was quantitated by liquid chromatography tandem mass spectrometry (LC-MS/MS) using positive electrospray ionization. The limit of detection and quantification for ketamine was found to be 0.5 and 1.6 ng/mL, respectively. The analysis exhibited linearity in the range of 10-500 ng/mL with coefficient of correlation >0.99. The recovery was found to be in the range of 89-107% with relative standard deviation (RSD) less than 10%. The prepared cartridge was found robust in extracting ketamine efficiently and repeatedly without any significant deterioration in its performance. Moreover, the batch-to-batch variations in the performance of the prepared cartridges in terms of % ion suppression of the extracts and recoveries of samples were small, suggesting the consistency in the properties of the monolith.

pH-resistant titania hybrid organic-inorganic coating for stir bar sorptive extraction of drugs of abuse in urine samples followed by high performance liquid chromatography-ultraviolet visible detection.

An organic-inorganic hybrid titania-hydroxy-terminated silicone oil (titania-OH-TSO) stir bar coating was prepared by sol-gel method. The extraction performance of titania-OH-TSO coated stir bar was evaluated and compared with poly(dimethysiloxane) (PDMS), poly(dimethysiloxane)-divinylbenzene (PDMS-DVB), poly(dimethysiloxane)-ß-cyclodextrin (PDMS-ß-CD) and C(18) coated stir bar with five polar drugs of abuse including amphetamine (PA), methamphetamine (MA), 3,4-methylenedioxyamphetamine (MDA), 3,4-methylenedioxymethamphetamine (MDMA) and ketamine (Ke) as the model analytes. The experimental results revealed that the titania-OH-TSO coated stir bar exhibited highly pH-resistant ability, good preparation reproducibility, superior selectivity and high extraction efficiency for the target compounds. Based on this fact, a new method of titania-OH-TSO coated stir bar sorptive extraction (SBSE) combined with high performance liquid chromatography (HPLC)-ultraviolet visible (UV) detection was developed for the analysis of five drugs of abuse in urine samples. The factors affecting the extraction efficiency of SBSE such as sample pH, desorption solvent, sample volume, extraction time, desorption time, stirring rate and ionic strength were investigated and the optimal extraction conditions were established. Under the optimized conditions, the limits of detection (LODs) for titania-OH-TSO coated SBSE-HPLC-UV determination of five polar drugs of abuse were in the range of 2.3-9.1 µg/L with relative standard deviations (RSDs) ranging from 7.3 to 8.9% (c=300 µg/L, n=6), and all of the target compounds exhibited good linearity over a concentration range of 30-3000 µg/L. The developed method was applied to the determination of amphetamines and Ke in urine samples of drug abusers with satisfactory results.

Micro-solid phase extraction coupled with high-performance liquid chromatography-tandem mass spectrometry for the determination of stimulants, hallucinogens, ketamine and phencyclidine in oral fluids.

A confirmatory method for the determination of illicit drugs based on micro-solid phase extraction with modified tips, made of a functionalized fiberglass with apolar chains of octadecylsilane into monolithic structure, has been developed in this study. Drugs belonging to different chemical classes, such as amphetamine, methamphetamine, methylenedioxyamphetamine, methylenedioxyethylamphetamine, methylenedioxymethylamphetamine, cocaine, benzoylecgonine, ketamine, mescaline, phencyclidine and psilocybine were analyzed. The quantitation was performed by liquid chromatography-tandem mass spectrometry and the analytes were detected in positive ionization by means of an electrospray source. The limits of quantification ranged between 0.3 ng mL(-1) for cocaine and 4.9 ng mL(-1) for psilocybine, with coefficients of determination (r(2)) >0.99 for all the analytes as recommended in the guidelines of Society of Forensic Toxicologists-American Association Forensic Sciences.

Disposable microfluidic device with ultraviolet detection for highly resolved screening of illicit drugs.

A disposable microfluidic device was constructed by conveniently integrating one poly(methyl methacrylate) board with four reservoirs and one fractured fused-silica capillary with 50 microm i.d. and 7.5 cm total length on a printed circuit board for applying sampling and separation voltages. The disposable microfluidic device combined with a home-made ultraviolet workstation could be conveniently used for efficient screening and quantitative detection of microg mL(-1) illicit drugs. Using eight illicit drugs as models, they could be baseline-separated within 240 s with the separation efficiency up to 600,047 plates m(-1) at the designed device. The novel device and proposed protocol were successfully used to screen illicit drugs in human urine. This work presented a simple and low-cost method to fabricate the microfluidic device and provided a powerful way for sensitive and specific multi-screening of different drugs with high resolution, fast separation and low-cost.