Solid-phase Extraction Efficiency Research Articles

Facile synthesis of conjugated microporous polymer with spherical structure for solid phase extraction of phenyl urea herbicides

A carbazolic conjugated microporous polymer (designated as CZ-CMP) was successfully synthesized through Scholl reaction of carbazole with 1, 3, 5-triphenylbenzene. The CZ-CMP was characterized by FT-IR spectrum, X-ray diffraction, nitrogen sorption isotherms, and scanning electron microscopy. The characterization results showed that the CZ-CMP had a spherical structure with high surface area and good microporosity. Its adsorption performance was investigated by applying it as an adsorbent for the solid phase extraction (SPE) of phenyl urea herbicides (PUHs) (metoxuron, chlortoluron, isoproturon, monolinuron and buturon) from tea drinks samples prior to high performance liquid chromatographic detection. The CZ-CMP displayed high extraction efficiency for the PUHs, and the primary factors affecting the SPE efficiency including the type and volume of the eluent, sample solution pH, sample loading rate and sample volume were optimized. Under the optimized conditions, a good linear response for the analytes was observed in the range of 0.10–80.0 ng mL−1 with correlation coefficients (r) from 0.9937 to 0.9997. The limits of detection were measured to be in the range of 0.02–0.30 ng mL−1 and the limits of quantitation were in the range of 0.06–0.9 ng mL−1. The developed method was successfully applied for the determination of the five PUHs in four different kinds of drinks with the method recoveries between 83.7% and 118% and the relative standard deviations between 1.0% and 10%. Besides, the application potential of the CZ-CMP was evaluated by using it to extract different types of the organic compounds including some phthalate eaters (PAEs), chlorophenol (CPs), nitroimidazoles and polycyclic aromatic hydrocarbons (PAHs). The results indicated that the CZ-CMP had strong adsorption ability for the compounds with more hydrogen bonding sites and moderate hydrophobicity.

Electrospun polystyrene nanofiber adsorbent for solid phase extraction of phenol as its quinoid derivative from aqueous solutions

In the present study, polystyrene nanofibers (PS NFs) were synthesized by electrospinning method and used as adsorbents in solid phase extraction of phenol from aqueous solutions. Phenol was reacted with 4-aminoantipyrine (4-AAP) reagent in presence of potassium hexacyanoferrate (III). The coloured product was extracted by solid phase extraction using electrospun synthesized polystyrene nanofibers and determined by UV-Vis spectrophotometer. At certain conditions of electrospinning process, the variables affecting the solid phase extraction efficiency were studied and optimized. Under the optimized conditions, (sorbent mass: 0.025 g PS NF, sample flow rate: 2.5 mL min−1, eluent: acetone: NaOH 0.1 M (1:1 v/v)), the linear dynamic range (LDR) and limit of detection (LOD as 3 Sb/m) for extraction of phenol from 50 mL of aqueous solutions were determined as 15-2500 µg L-1 and 10 µg L-1, respectively. The precision (as RSD %) of the extraction method using the proposed adsorbent was lower than 7.6%. Finally, the applicability of the proposed method for the extraction of phenol from industrial aqueous samples was examined and satisfactory results were obtained.

Enhanced solid phase extraction of DNA using hydrophilic monodisperse poly(methacrylic acid-co-ethylene dimethacrylate) microparticles.

The efficiency of solid phase extraction (SPE) of DNA on polymer particles is limited by the features of the applied solid support, such as size, hydrophilicity, and functionality and their application in SPE also requires additional steps and compounds to finally obtain sufficient amount of high-quality DNA. The present study describes a preparation of sub-micrometer monodisperse poly(methacrylic acid-co-ethylene dimethacrylate) (PME) particles by precipitation polymerization. The effect of the ethylene dimethacrylate (EDMA) crosslinker concentration on morphology and particle size, which varied from 730 to 900nm, was investigated. The particles with 5 and 15wt% EDMA were selected for a study of SPE of plasmid DNA under various adsorption and elution conditions, followed by the enzymatic restriction of isolated DNA to verify a quality the nucleic acid. The particles with 15wt% EDMA were suitable for the SPE because they retained better colloidal stability during the adsorption without additional induction of DNA conformational change. The quality of isolated DNA was finally verified by enzymatic restriction by restriction endonuclease EcoRI. Moreover, the developed method using PME particles was successfully utilized for DNA isolation from Escherichia coli lysate.

Selective determination of sartan drugs in environmental water samples by mixed-mode solid-phase extraction and liquid chromatography tandem mass spectrometry

Herein, a method for the simultaneous determination of the currently prescribed sartan drugs (eprosartan, EPR; olmesartan, OLM; losartan, LOS; candesartan, CAN; telmisartan, TEL; irbesartan, IRB; and valsartan, VAL), and the biodegradation product valsartan acid (VALA), in water samples (raw and treated wastewater, river and tap water) was developed. Solid-phase extraction (SPE) and ultra-performance liquid chromatography (UPLC) tandem mass spectrometry (MS/MS) were employed as concentration and determination techniques, respectively. Different sorbents and elution solvents were tested for sample preparation. Under optimized conditions, samples at neutral pH (6–8 units) were concentrated using mixed-mode (reversed-phase and anionic exchange) cartridges. Thereafter, the sorbent was washed with 5 mL of a methanol: water (1:1) solution, dried under a nitrogen stream and compounds were eluted with 2 mL of methanol: NH3 (98:2). The accuracy of the method (accounting for SPE efficiency and matrix effects during electrospray ionization) was investigated using solvent-based calibration standards. Global recoveries, obtained for different water matrices (tap, river, treated and raw wastewater), ranged from 82% to 134%, with standard deviations between 2 and 18%. LOQs varied from 2 to 50 ng L−1. Analysis of un-spiked samples confirmed: (1) the incomplete removal of sartans at sewage treatment plants (STPs), (2) the formation of VALA during municipal water treatment, and (3) the presence of VALA in the processed tap water samples. Additional findings of the current study are the detection of hydroxylated derivatives of the sartan drugs IRB and LOS in wastewater, and the E-Z isomerization of EPR in environmental water samples.

Composite MOFs as adsorbents for solid phase extraction combined with high performance liquid chromatography for the determination of polycyclic aromatic hydrocarbons in water

Metal-organic frameworks (MOFs) are a kind of porous materials, which has large specific surface area, high porosity, diverse structure, excellent thermal stability and solvent stability etc. So, it has attracted extensive attention as an adsorbent for solid phase extraction (SPE). Polycyclic aromatic hydrocarbons (PAHs) are a kind of persistent organic pollutants that can lead serious hurts to the ecological environment and human health. The purpose of this paper is to optimize the types and proportion of mixed lanthanum based MOFs, and to improve the enrichment efficiency of SPE. Then a method to analysis PAHs by SPE-HPLC was established. Several main factors that could effected the pre-treatment efficient, such as the amount of adsorbent, the amount and pH of PAHs water sample, and the volume of eluent, were investigated. After optimized, the extraction of seven PAHs in water sample was achieved and the recovery rates were 80.67%, 80.06%, 54.69%, 82.62%, 118.87%, 70.30% and 95.57% respectively.

Preparation of hydrophilic, magnetic molecularly imprinted resins of chlorogenic acid and evaluation of its solid-phase extraction performance

Hydrophilic, magnetic molecularly imprinted resins (MMIRs) were fabricated inside Fe3O4@mSiO2 pores by the one-pot copolycondensation of chlorogenic acid (CGA), resorcinol, melamine, and formaldehyde. The final porous MMIRs with larger numbers of surface recognition sites were obtained by removing mSiO2. The successful preparation of MMIRs was confirmed using transmission electron microscopy, Fourier transform infrared spectroscopy, vibrating sample magnetometry, thermo-gravimetric analysis, and water contact angle analysis. The analyses suggest that the MMIRs have excellent hydrophilicity and magnetic solid-phase extraction efficiency. The MMIRs had a good adsorption capacity (50.87 mg/g), fast rate of adsorption (equilibrium was attained at 70 min), and specific recognition for CGA. The MMIRs, in combination with high performance liquid chromatography, were directly used for the selective extraction and determination of CGA in Duzhong brick tea. The limit of detection and recovery were 0.7 mg/L and 93.1%-109.4%, respectively, with relative standard deviations of less than 9.6%. The proposed strategy was extremely promising for the facile, rapid, and selective determination of CGA in real aqueous samples.

High-throughput and selective solid-phase extraction of urinary catecholamines by crown ether-modified resin composite fiber

In the present study, we developed a simple and high-throughput solid phase extraction (SPE) procedure for selective extraction of catecholamines (CAs) in urine samples. The SPE adsorbents were electrospun composite fibers functionalized with 4-carboxybenzo-18-crown-6 ether modified XAD resin and polystyrene, which were packed into 96-well columns and used for high-throughput selective extraction of CAs in healthy human urine samples. Moreover, the extraction efficiency of packed-fiber SPE (PFSPE) was examined by high performance liquid chromatography coupled with fluorescence detector. The parameters affecting the extraction efficiency and impurity removal efficiency were optimized, and good linearity ranging from 0.5 to 400 ng/mL was obtained with a low limit of detection (LOD, 0.2–0.5 ng/mL) and a good repeatability (2.7%–3.7%, n = 6). The extraction recoveries of three CAs ranged from 70.5% to 119.5%. Furthermore, stable and reliable results obtained by the fluorescence detector were superior to those obtained by the electrochemical detector. Collectively, PFSPE coupled with 96-well columns was a simple, rapid, selective, high-throughput and cost-efficient method, and the proposed method could be applied in clinical chemistry.

Dispersive magnetic solid-phase extraction of phthalate esters from water samples and human plasma based on a nanosorbent composed of MIL-101(Cr) metal-organic framework and magnetite nanoparticles before their determination by GC-MS.

In this study, a magnetic metal-organic framework was synthesized simply and utilized in the dispersive magnetic solid-phase extraction of five phthalate esters followed by their determination by gas chromatography with mass spectrometry. First, MIL-101(Cr) was prepared hydrothermally in water medium without using highly corrosive hydrofluoric acid, utilizing an autoclave oven heat supply. Afterward, Fe3 O4 nanoparticles were decorated into the matrix of MIL-101(Cr) to fabricate magnetic MIL-101 nanocomposite. The nanocomposite was characterized by various techniques. The parameters affecting dispersive magnetic solid-phase extraction efficiency were optimized and obtained as: a sorbent amount of 15mg; a sorption time of 20min; an elution time of 5min; NaCl concentration, 10% w/v; type and volume of the eluent 1mL n-hexane/acetone (1:1 v/v). Under the optimum conditions detection limits and linear dynamic ranges were achieved in the range of 0.08-0.15 and 0.5-200μg/L, respectively. The intra- and interday RSD% values were obtained in the range of 2.5-9.5 and 4.6-10.4, respectively. Ultimately, the applicability of the method was successfully confirmed by the extraction and determination of the model analytes in water samples, and human plasma in the range of microgram per liter and satisfactory results were obtained.

Development and optimization of gas chromatography coupled to high resolution mass spectrometry based method for the sensitive determination of Dechlorane plus and related norbornene-based flame retardants in food of animal origin

An analytical method has been developed for the trace determination of 10 dechlorane-related compounds (DRCs) in food products by gas chromatography – high resolution mass spectrometry (GC-HRMS). The highest sensitivity of this instrumental analysis method was achieved by selection of the GC column type, optimization of the heated zones within the instrument, and adjusting the electron impact energy. The efficiency of solid phase extraction as clean-up procedure was also optimized. Two different types of cartridges - neutral silica gel and Florisil®, as well as seven organic solvents or their mixtures - n-hexane, cyclohexane, acetone, toluene, n-hexane/ethyl acetate, n-hexane/acetone, and n-hexane/dichloromethane - were evaluated. The analytical method was characterized as selective, precise, accurate, and linear over the concentration ranges from 1.00 to 100 pg μL−1 for DRCs. Ultra-trace level sensitivity was achieved with the instrumental limits of quantification (i-LOQs) varying from ∼0.01 pg to ∼ 1 pg and method limits of quantification (m-LOQs) by the analysis of 10 g of sample varying from ∼0.04 to ∼ 5 pg g−1. The developed method was successfully applied for the analysis of food samples and the analyses revealed the presence of majority of selected DRCs, with the Dechlorane Plus (DP) isomers occurring to a greater extent, pointing to the highest levels in cod liver and other fish products.

Nickel Iso-nicotine MOFs as Adsorbent of Solid Phase Extraction for Determination of Polycyclic Aromatic Hydrocarbon in Water

The method of solid phase extraction (SPE) combined with high performance liquid chromatography (HPLC) was established while nickel iso-nicotine MOFs was employed as adsorbent of SPE to concentrate eight kinds of PAHs in water. The chromatographic conditions, such as flow rate of mobile phase and composition of mobile phase, were investigated. Several important factors of extraction efficiency of SPE, including mass of absorbent, volume of water sample, content of methanol and pH were discussed. The detection limit, precision and recovery rate were calculated.

Multi-template imprinted polymers for simultaneous selective solid-phase extraction of six phenolic compounds in water samples followed by determination using capillary electrophoresis

Novel multi-template molecularly imprinted polymers (mt-MIPs) with six phenolic compounds as the template, namely phenol, 4-chlorophenol (4-CP), 2,4,6-trichlorophenol (2,4,6-TCP), 2,4-dichlorophenol (2,4-DCP), 2-chlorophenol (2-CP) and 2,6-dichlorophenol (2,6-DCP), were prepared by precipitation polymerization and used as the adsorbents of solid-phase extraction (SPE), and coupled with capillary electrophoresis (CE) for the simultaneous selective extraction, separation and determination of trace phenolic compounds in water samples. The resultant mt-MIPs exhibited uniform spherical morphology, large specific surface area and high thermal stability, and offered high selectivity towards the six template phenolic compounds. Various parameters affecting the molecularly imprinted SPE (MISPE) efficiency were investigated in detail, and excellent CE separation was realized within 7min. Good linearity was obtained in the range of 1–200μgL−1 for phenol and 4-CP, and 1–300μgL−1 for 2,4,6-TCP, 2,4-DCP, 2-CP and 2,6-DCP. High sensitivity was attained with low limits of detection and quantification ranging from 0.17 to 0.31μgL−1 and 0.57 to 1.03μgL−1, respectively. Satisfactory recoveries for spiked reservoir water, river water, tannery wastewater and tap water samples were achieved in the range of 82.13–105.63% with relative standard deviations within 1.68–6.96%. The developed MISPE-CE method proved practically feasible for simultaneous selective extraction/enrichment, separation and sensitive determination of multiple targets in complicated aqueous matrices.

Efficiency evaluation of extraction methods of selected benzodiazepine derivatives from human serum and whole blood and the reactivity phenomenon in immunoassay for benzodiazepines

The aim of the study was to compare efficiency of various extraction methods of benzodiazepine derivatives: diazepam, estazolam, flunitrazepam and nitrazepam. The study compared the recovery of benzodiazepines isolated from biological material (blood and human blood serum) using liquid-liquid extraction and solid-phase extraction. The efficiency of each extraction was evaluated using high-performance liquid chromatography with diode array detector. In addition, benzodiazepines immunoassay reactivity was estimated. The following methods of extraction were used: liquid-liquid extraction (a classical liquid-liquid extraction and microextraction), solid- -phase extraction (Baker’s columns and United Chemical Technologies’ (UTC columns). The reactivity was evaluated using V-Twin System with EMIT technology by Siemens. The results showed that the lowest recovery (nitrazepam – 16%, diazepam – 23%, flunitrazepam – 28%, estazolam – 37%) was obtained using liquid-liquid microextraction of whole blood and the highest recovery was obtained in solid-phase extraction of whole blood using United Chemical Technologies’ columns (nitrazepam – 86%, diazepam – 89%, estazolam – 91%, flunitrazepam – 94%). The lowest recovery in classical liquid-liquid extraction was obtained for diazepam isolated from whole blood (36%), and the highest – for flunitrazepam isolated from serum (74%). Solid-phase extraction with Baker’s columns was successful only in case of drugs isolation from serum and the recovery range from 57% to 89% for flunitrazepam. The results indicated higher efficiency of solid-phase extraction, especially with use of columns specific for the extraction of benzodiazepines. The immunoassay analysis showed a decreased reactivity of the tested benzodiazepine derivatives on the reagent used for the EMIT assay. Comparative analysis of the recovery efficiency of selected benzodiazepine derivatives led to the conclusion that use of solid-phase extraction should be considered more often in routine toxicological analysis. The knowledge of benzodiazepine derivatives cross-reactivity in immunoassay method is essential for correct interpretation of obtained results.

Carbon nanotube sponges as a solid-phase extraction adsorbent for the enrichment and determination of polychlorinated biphenyls at trace levels in environmental water samples

Carbon nanotube (CNT) sponges has recently attracted considerable attention in numerous fields because of its excellent properties, such as high porosity, light weight, and large surface area. The potential of CNT sponges for the solid-phase extraction (SPE) of organic pollutants at trace levels was investigated in this study for the first time. Seven polychlorinated biphenyls (PCBs) were selected as analytes, and gas chromatography–tandem mass spectrometry was employed for the detection. We optimized important parameters that may influence the efficiency of SPE, including the kind and volume of elution solvent, sample pH, and sample flow rate and volume. Under optimized conditions, low limits of detection (0.72–1.98ngL–1), wide range of linearity (10–1000ngL−1) and good repeatability (2.69–6.85%, n=5) were obtained. CNT sponges exhibited higher extraction performance than other adsorbent materials under the optimized conditions. Real environmental water samples were analyzed, and satisfactory recoveries (81.1–119.1%) were achieved. All these results demonstrated that CNT sponges are suitable SPE material for the enrichment and sensitive determination of PCBs at trace levels.

Comparison of the solid-phase extraction efficiency of a bounded and an included cyclodextrin-silica microporous composite for polycyclic aromatic hydrocarbons determination in water samples

Solid-phase extraction is one of the most important techniques for sample purification and concentration. A wide variety of solid phases have been used for sample preparation over time. In this work, the efficiency of a new kind of solid-phase extraction adsorbent, which is a microporous material made from modified cyclodextrin bounded to a silica network, is evaluated through an analytical method which combines solid-phase extraction with high-performance liquid chromatography to determine polycyclic aromatic hydrocarbons in water samples. Several parameters that affected the analytes recovery, such as the amount of solid phase, the nature and volume of the eluent or the sample volume and concentration influence have been evaluated. The experimental results indicate that the material possesses adsorption ability to the tested polycyclic aromatic hydrocarbons. Under the optimum conditions, the quantification limits of the method were in the range of 0.09–2.4μgL−1 and fine linear correlations between peak height and concentration were found around 1.3–70μgL−1. The method has good repeatability and reproducibility, with coefficients of variation under 8%. Due to the concentration results, this material may represent an alternative for trace analysis of polycyclic aromatic hydrocarbons in water trough solid-phase extraction.

Simultaneous determination of copper, cobalt, and mercury ions in water samples by solid-phase extraction using carbon nanotube sponges as adsorbent after chelating with sodium diethyldithiocarbamate prior to high performance liquid chromatography.

Recently, a sponge-like material called carbon nanotube sponges (CNT sponges) has drawn considerable attention because it can remove large-area oil, nanoparticles, and organic dyes from water. In this paper, the feasibility of CNT sponges as a novel solid-phase extraction (SPE) adsorbent for the enrichment and determination of heavy metal ions (Co(2+), Cu(2+), and Hg(2+)) was investigated for the first time. Sodium diethyldithiocarbamate (DDTC) was used as the chelating agent and high performance liquid chromatography (HPLC) for the final analysis. Important factors which may influence extraction efficiency of SPE were optimized, such as the kind and volume of eluent, volume of DDTC, sample pH, flow rate, etc. Under the optimized conditions, wide range of linearity (0.5-400μgL(-1)), low limits of detection (0.089~0.690μgL(-1); 0.018~0.138μg), and good repeatability (1.27~3.60%, n = 5) were obtained. The developed method was applied for the analysis of the three metal ions in real water samples, and satisfactory results were achieved. All of these findings demonstrated that CNT sponges will be a good choice for the enrichment and determination of target ions at trace levels in the future.

Evaluation of solid phase extraction efficiency of functionalized biochar for polyphenols from Punica granatum

AbstractThe biochars functionalized with polyethylimine (BPE), orthosilicate and polyaniline were evaluated for solid phase extraction of pomegranate phenolics, namely gallic acid, rutin, ellagic acid, naringin, quercetin, apigenin and kaempferol. Characterization of composites of biochar for morphology, functional group and elemental composition has been done. Solid phase extraction cartridges packed with these composites were used for extraction. Most of these biochar composites attained nano‐sized porous structure. Functional group analysis suggests that oxygenated groups of biochar were interacted with electrophilic primary amines and polysilane chain of polyethylimine and orthosilicate, respectively. The formation of biochar‐polyaniline composite occurred through emeraldine base. All composites exhibited good retention capacity for all phenolics except kaempferol. BPE composites were found suitable for recovery of ellagic acid at present solvent system (aqueous methanol). The process was optimized by a quadratic model suggesting the pre‐concentration (60–95%) of ellagic acid (quadratic polynomial relationship, r2 = 1.00). Breakthrough curves were derived for the ellagic acid, which provide the information of retention equilibrium volume, column capacity and recovery of ellagic acid for the BPE packed solid phase extraction cartridges. © 2015 Curtin University of Technology and John Wiley & Sons, Ltd.

Multi-walled carbon nanotubes as solid-phase extraction sorbents for simultaneous determination of type A trichothecenes in maize, wheat and rice by ultra-high performance liquid chromatography-tandem mass spectrometry

A solid-phase extraction (SPE) procedure using multi-walled carbon nanotubes (MWCNTs) as sorbents coupled with ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) was developed for simultaneous determination of four type A trichothecenes in maize, wheat and rice for the first time. Several key parameters including the composition of sample loading solutions, washing and elution solvents were thoroughly investigated to achieve optimal SPE recoveries and efficiency. Performance of the MWCNTs materials was significantly affected by pH, and after optimization, n-hexane and 5% methanol aqueous solution as the washing solutions and methanol containing 1% formic acid as the elution solvent presented an excellent purification efficiency for the four targets in the different matrices. The method was validated by determining the linearity (R2≥0.992), recovery (73.4–113.7%), precision (1.2–17.1%) and sensitivity (limit of quantification in the range of 0.02–0.10μg/kg), and was further applied for simultaneous determination of type A trichothecenes in 30 samples. Although low contamination levels of type A trichothecenes in wheat, maize and rice were observed revealing mitigated risks to consumers in Shanghai, China, the developed method has proven to be a valuable tool for type A trichothecenes monitoring in complex crop matrices.

Solid-phase extraction of l-tryptophan from food samples utilizing a layered double hydroxide nano-sorbent prior to its determination by spectrofluorometry

In this research, a simple method was developed for the separation and determination of l-tryptophan in aqueous solutions. The method consists of a solid-phase extraction (SPE) cleanup system utilizing a column packed with nickel–aluminum layered double hydroxide as a nano-sorbent, followed by a spectrofluorometric detection step. Some factors influencing the SPE efficiency, including pH, the sample flow rate, the elution conditions and the amount of nano-sorbent were evaluated and optimized. The selectivity of the presented SPE method with regard to l-tryptophan was studied in the presence of other amino acids and potentially interfering ions. Under optimum conditions, the calibration graph was linear in the range of 0.1–120.0 µg L−1 with a correlation coefficient of 0.9975. The limit of detection and relative standard deviation for l-tryptophan were 0.01 µg L−1 and 0.62 %, respectively. The maximum sorption capacity of the sorbent for l-tryptophan was 37.6 mg g−1. The method was successfully applied to determine l-tryptophan in several food samples with recoveries in the range of 96.2–104.2 % for the spiked samples.

Optimization of Solid Phase Extraction Method for Quantitative Analysis of Perfluorooctanoic Acid in Serum using Liquid Chromatography-Tandem Mass Spectrometry

A solid phase extraction (SPE) method was optimized for the quantitative analysis of perfluorooctanoic acid (PFOA)in serum using hydrophilic-lipophilic balance SPE and LC-MS/MS. Fetal bovine serums spiked with 13C8-PFOA before or afterSPE were used as test samples for evaluation of the SPE efficiency. Simultaneous evaluation of matrix effects and absolute SPErecovery for 13C8-PFOA in serum using different sample pre-treatments and SPE conditions allowed optimization of SPE processefficiency with minimal matrix effect and decent SPE recovery. Introduction of protein precipitation as a sample pre-treatmentprocedure for serum samples before SPE generally decreased matrix effect in LC-MS/MS analysis and provided morestable recovery of PFOA.

Cannabinoids in Exhaled Breath following Controlled Administration of Smoked Cannabis

Δ(9)-Tetrahydrocannabinol (THC), 11-nor-9-carboxy-THC (THCCOOH), and cannabinol (CBN) were measured in breath following controlled cannabis smoking to characterize the time course and windows of detection of breath cannabinoids. Exhaled breath was collected from chronic (≥4 times per week) and occasional (<twice per week) smokers before and after smoking a 6.8% THC cigarette. Sample analysis included methanol extraction from breath pads, solid-phase extraction, and liquid chromatography-tandem mass spectrometry quantification. THC was the major cannabinoid in breath; no sample contained THCCOOH and only 1 contained CBN. Among chronic smokers (n = 13), all breath samples were positive for THC at 0.89 h, 76.9% at 1.38 h, and 53.8% at 2.38 h, and only 1 sample was positive at 4.2 h after smoking. Among occasional smokers (n = 11), 90.9% of breath samples were THC-positive at 0.95 h and 63.6% at 1.49 h. One occasional smoker had no detectable THC. Analyte recovery from breath pads by methanolic extraction was 84.2%-97.4%. Limits of quantification were 50 pg/pad for THC and CBN and 100 pg/pad for THCCOOH. Solid-phase extraction efficiency was 46.6%-52.1% (THC) and 76.3%-83.8% (THCCOOH, CBN). Matrix effects were -34.6% to 12.3%. Cannabinoids fortified onto breath pads were stable (≤18.2% concentration change) for 8 h at room temperature and -20°C storage for 6 months. Breath may offer an alternative matrix for identifying recent driving under the influence of cannabis, but currently sensitivity is limited to a short detection window (0.5-2 h).