Hydrophobic eutectic solvents for surface water treatment with a focus on benzophenone type UV filters.

Effective removal of organic UV filters from aquatic environmental compartments and swimming waters is very important because these substances are hazardous to humans and wildlife at low concentrations and act as endocrine disruptors. Therefore, the aim of the present article is to determine the extraction efficiencies of hydrophobic deep eutectic solvents (HDES) for the selected UV filters based on benzophenone structure (benzophenone, 2,4-dihydroxybenzophenone, 2,2´,4,4´-tetrahydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2,2´-dihydroxy-4-methoxybenzophenone, 4-methacryloxy-2-hydroxybenzophenone) from aqueous matrices. For this purpose, six HDESs based on dl-menthol in combination with caprylic, decanoic and lauric acid are prepared and compared with referent terpene solvents such as terpineol and linalool. The effect of various parameters such as HDES composition, volume ratio, frequency and shaking time are studied. The highest extraction efficiency is shown by HDES of menthol:caprylic acid (1:1) composition at the aqueous:organic phase volume ratio of 1:1, shaking frequency of 1500 rpm and shaking time of 15 min. The achieved extraction efficiencies are higher than 99.6 % for all benzophenones studied in the purification of stagnant pond water, swimming pool water and river water samples. After a simple and fast sample treatment, the residual levels of benzophenones in the waters are controlled by a newly developed sensitive HPLC-MS/MS method with LOQs in the range of 0.7 - 5.0 ng/mL.

Methoxetamine and its metabolites: Postmortem determination in body fluids of human cadaver.

We report the forensic case of a 42-year-old man, a known drug user, who died at home and whose body was only discovered 2 months later. Autopsy was performed on a corpse in the late postmortem stage where no apparent cause of death was found. A toxicological screening of biological materials (blood, urine and gastric content) using liquid chromatography with different types of mass detection (ion trap and high-resolution) revealed the presence of methoxetamine (MXE), a ketamine analog, and its metabolites. MXE and a number of its metabolites (e.g., O-desmethyl, N-desethyl, hydroxy, glucuronides and sulfates) were identified in urine. Based on the results, a method using liquid chromatography with tandem mass spectrometry was developed and validated for the determination of MXE concentration in biological materials. The following values of MXE concentration were found: blood-3.6 ng/mL, urine-70.5 ng/mL and gastric content-18.0 ng/mL. Given the absence of other drugs, medications and poisons, it can be inferred that despite relatively low blood concentrations, MXE contributed to the victim's death. The present case demonstrates that even after 2 months, MXE and its several metabolites can be detected and determined in the human cadaver at a relatively advanced stage of decomposition.

Plasma concentrations of levobupivacaine in neonates during caudal epidural analgesia maintained over 48 hours.

BACKGROUND: Differences in neonatal pharmacokinetics are known to cause systemic accumulation of levobupivacaine with adverse effects during epidural analgesia. Therefore, it is not recommended to surpass 48 hours of administration in neonates. Free and total levobupivacaine levels are considered as predictors of toxicity. OBJECTIVE: The aim of the LEVON pilot study was to detect the accumulation of levobupivacaine during epidural analgesia exceeding 48 hours in neonates. METHODS: Ten neonates received a loading dose of levobupivacaine (1.25 mg/kg) followed by a continuous infusion (0.2 mg/kg/hour) epidurally. Free and total levobupivacaine concentrations were measured 0.5, 1, 6, 12, 36, 72 and 144 hours after the start of infusion. Cumulative doses of levobupivacaine, pain scores and clinical signs of toxicity were used for assessing efficacy and safety. RESULTS: The median concentrations of total levobupivacaine were 586.0, 563.0, 837.5, 957.0, 1930.0, 708.5 and 357.5 ng/ml. The median concentrations of free levobupivacaine were 4.0, 3.6, 5.5, 3.6, 5.5, 0.8 and 0.0 ng/ml. Three patients reached concerning concentrations of total levobupivacaine. Levels of free levobupivacaine remained low. No signs of toxicity were observed. CONCLUSION: Caudal epidural analgesia with levobupivacaine lasting longer than 48 hours appears to be safe providing that free levobupivacaine levels are below the presumed threshold for toxicity (Tab. 1, Fig. 1, Ref. 29). Text in PDF www.elis.sk Keywords: free levobupivacaine, total levobupivacaine, neonate, caudal continuous epidural analgesia, postoperative pain.

Monitoring of circulating amino acids in patients with pancreatic cancer and cancer cachexia using capillary electrophoresis and contactless conductivity detection.

Branched chain amino acids (BCAAs), alanine and glutamine are determined in human plasma by capillary electrophoresis with contactless conductivity detection (CE/C4 D). The baseline separation of five amino acids from other plasma components is achieved on the short capillary effective length of 18 cm in 3.2 mol/L acetic acid with addition of 13% v/v methanol as background electrolyte. Migration times range from 2.01 min for valine to 2.84 min for glutamine, and LODs for untreated plasma are in the interval 0.7-0.9 µmol/L. Sample treatment is based on the addition of acetonitrile to only 15 µL of plasma and supernatant is directly subjected to CE/C4 D. Circulating amino acids are measured in patients with pancreatic cancer and cancer cachexia during oral glucose tolerance test. It is shown that patients with pancreatic cancer and cancer cachexia syndrome exhibit low basal circulating BCAAs and glutamine levels and loss of their insulin-dependent suppression.

Anticonvulsive Effects and Pharmacokinetic Profile of Cannabidiol (CBD) in the Pentylenetetrazol (PTZ) or N-Methyl-D-Aspartate (NMDA) Models of Seizures in Infantile Rats.

In spite of use of cannabidiol (CBD), a non-psychoactive cannabinoid, in pediatric patients with epilepsy, preclinical studies on its effects in immature animals are very limited. In the present study we investigated anti-seizure activity of CBD (10 and 60 mg/kg administered intraperitoneally) in two models of chemically induced seizures in infantile (12-days old) rats. Seizures were induced either with pentylenetetrazol (PTZ) or N-methyl-D-aspartate (NMDA). In parallel, brain and plasma levels of CBD and possible motor adverse effects were assessed in the righting reflex and the bar holding tests. CBD was ineffective against NMDA-induced seizures, but in a dose 60 mg/kg abolished the tonic phase of PTZ-induced generalized seizures. Plasma and brain levels of CBD were determined up to 24 h after administration. Peak CBD levels in the brain (996 ± 128 and 5689 ± 150 ng/g after the 10- and 60-mg/kg doses, respectively) were reached 1-2 h after administration and were still detectable 24 h later (120 ± 12 and 904 ± 63 ng/g, respectively). None of the doses negatively affected motor performance within 1 h after administration, but CBD in both doses blocked improvement in the bar holding test with repeated exposure to this task. Taken together, anti-seizure activity of CBD in infantile animals is dose and model dependent, and at therapeutic doses CBD does not cause motor impairment. The potential risk of CBD for motor learning seen in repeated motor tests has to be further examined.

Large volume sample stacking of antiepileptic drugs in counter current electrophoresis performed in PAMAPTAC coated capillary.

Electrophoretic stacking is developed for sensitive determination of three zwitterionic antiepileptics, namely vigabatrin, pregabalin and gabapentin, in human serum. CE separation is performed in a 25 µm fused silica capillary covalently coated with the copolymer of acrylamide with 5% content of permanently charged 3-acrylamidopropyl trimethylammonium chloride (PAMAPTAC). In background electrolyte of 500 mM acetic acid, the 5% PAMAPTAC generates an anodic electro-osmotic flow with a magnitude of (-18.6 ± 0.5) · 10-9 m2V-1s-1, which acts against the direction of the electrophoretic migration of the analytes. A sample of the antiepileptic prepared in a 25% v/v infusion solution and 75% v/v acetonitrile is injected into the capillary in a large volume attaining a zone length of up to 270 mm. After turning on the separation voltage, the antiepileptics are isotachophoretically focussed behind the zone of Na+ ions with a sensitivity enhancement factor of 78. For the clinical determination of antiepileptics, the human serum is diluted with acetonitrile in a ratio of 1:3 v/v and a zone with a length of 90 mm is injected into the capillary. The method is linear in the 0.025-2.5 µg/mL concentration range; the attained limit of quantification is in the range 18.3-22.8 nmol/L; the within-day precision for the migration time is 0.8-1.2% and for the peak area 1.5-2.4%.

Sensitive CE-MS method for monitoring of riociguat and desmethylriociguat levels in human serum.

Riociguat is novel antihypertensive drug for treatment of pulmonary hypertension. As such, it is still being tested in many clinical and pharmacokinetic trials. Existing methods that determine serum riociguat and desmethylriociguat (DMR) are based solely on liquid chromatography with mass spectrometry. Therefore, we present a novel capillary electrophoresis with mass spectrometry method (CE-MS) for their determination in human serum as alternative method for ongoing trials. Complete resolution of both analytes was achieved by means of pH optimization of ammonium formate background electrolytes that are fully compatible with ESI/MS detection. Simple liquid-liquid extraction was used as sample pretreatment. The calibration dependence of the method was linear (in the range of 10-1000 ng/mL), with adequate accuracy (90.1-114.9%) and precision (13.4%). LOD and LOQ were arbitrarily set at 10 ng/mL for both analytes. Clinical applicability was validated using serum samples from patients treated with riociguat in pharmacokinetic study and the results corresponded with reference HPLC-MS/MS values. Capillary electrophoresis proved to be sensitive and selective tool for the analysis of riociguat and DMR.

Population pharmacokinetics of riociguat and its metabolite in patients with chronic thromboembolic pulmonary hypertension from routine clinical practice.

Pharmacokinetic data for riociguat in patients with chronic thromboembolic pulmonary hypertension (CTEPH) have previously been reported from randomized clinical trials, which may not fully reflect the population encountered in routine practice. The aim of the current study was to characterize the pharmacokinetic of riociguat and its metabolite M1 in the patients from routine clinical practice. A population pharmacokinetic model was developed in NONMEM 7.3, based on riociguat and its metabolite plasma concentrations from 49 patients with CTEPH. One sample with riociguat and M1 concentrations was available from each patient obtained at different time points after last dose. Age, bodyweight, sex, smoking status, concomitant medications, kidney and liver function markers were tested as potential covariates of pharmacokinetic of riociguat and its metabolite. Riociguat and M1 disposition was best described with one-compartment models. Apparent volume of distribution (Vd/F) for riociguat and M1 were assumed to be the same. Total bilirubin and creatinine clearance were the most predictive covariates for apparent riociguat metabolic clearance to M1 (CLf,M1/F) and for apparent riociguat clearance through remaining pathways (CLe,r/F), respectively. CLf,M1/F, CLe,r/F, Vd/F of riociguat and M1, and clearance of M1 (CLe,M1/F) for a typical individual with 70 mL/min creatinine clearance and 0.69 mg/dL total bilirubin were 0.665 L/h (relative standard error = 17%)), 0.66 (18%) L/h, 3.63 (15%) L and 1.47 (19%) L/h, respectively. Upon visual identification of six outlying individuals, an absorption lag-time of 2.95 (6%) h was estimated for these patients. In conclusion, the only clinical characteristics related to riociguat exposure in patients with CTEPH from routine clinical practice are total bilirubin and creatinine clearance. This confirms the findings of the previous population pharmacokinetic studies based on data from randomized clinical trials.

Development of a CE-MS method for the study of riociguat and metabolite M1 in pharmaceutical analysis.

Riociguat is a novel antihypertensive drug for the treatment of pulmonary hypertension. We present electrophoretic characterization, i.e. migration behavior of riociguat and metabolite M1 as support for optimized CZE/MS assay. Fundamental separation parameters, such as peak width, symmetry, and resolution are studied in a series of ammonium formate buffers within pH range 2.60-5.61. The narrow region of peak symmetry lies close to pH 4.0 for both analytes. Accordingly, the value of resolution maximizes in a background electrolyte adjusted to pH 4.10. Basic calibration parameters estimated from CZE experiments with absorption photometric and mass spectrometric detection of riociguat and metabolite M1 were evaluated. More than three orders lower LOD was achieved with high resolution mass spectrometric detection. The observed difference in the sensitivity of both detection techniques gives priority to the utilization of CZE/MS in practice. The values of dissociation constants of riociguat and metabolite M1, pKBH , were determined from CZE measurements in lithium formate and lithium acetate background electrolytes with constant ionic strength. The value of pKBH = 4.30 ± 0.02 for riociguat corresponds well to the value already presented in the literature. According to our observation, metabolite M1 behaves like a slightly stronger base with estimated pKBH = 4.40 ± 0.02.

Cannabis-induced altered states of consciousness are associated with specific dynamic brain connectivity states.

BACKGROUND: Cannabis, and specifically one of its active compounds delta-9-tetrahydrocannabinol in recreational doses, has a variety of effects on cognitive processes. Most studies employ resting state functional magnetic resonance imaging techniques to assess the stationary effects of cannabis and to-date one report addressed the impact of delta-9-tetrahydrocannabinol on the dynamics of whole-brain functional connectivity. METHODS: Using a repeated-measures, within-subjects design, 19 healthy occasional cannabis users (smoking cannabis ⩽2 per week) underwent resting state functional magnetic resonance imaging scans. Each subject underwent two scans: in the intoxicated condition, shortly after smoking a cannabis cigarette, and in the non-intoxicated condition, with the subject being free from cannabinoids for at least one week before. All sessions were randomized and performed in a four-week interval. Data were analysed employing a standard independent component analysis approach with subsequent tracking of the functional connectivity dynamics, which allowed six connectivity clusters (states) to be individuated. RESULTS: Using standard independent component analysis in resting state functional connectivity, a group effect was found in the precuneus connectivity. With a dynamic independent component analysis approach, we identified one transient connectivity state, characterized by high connectivity within and between auditory and somato-motor cortices and anti-correlation with subcortical structures and the cerebellum that was only found during the intoxicated condition. Behavioural measures of the subjective experiences of changed perceptions and tetrahydrocannabinol plasma levels during intoxication were associated with this state. CONCLUSIONS: With the help of the dynamic connectivity approach we could elucidate neural correlates of the transitory perceptual changes induced by delta-9-tetrahydrocannabinol in cannabis users, and possibly identify a biomarker of cannabis intoxication.

Salting out assisted liquid-liquid extraction for liquid chromatography tandem-mass spectrometry determination of amphetamine-like stimulants in meconium.

In the last decade there has been a dramatic increase in the availability and abuse of synthetic cathinones - new amphetamine-like stimulants. Even though their abuse during pregnancy could have serious adverse effects on the fetus, cathinones are not readily included in neonatal toxicological screenings. Meconium (first neonatal stool) is the specimen of choice to reveal long term drug exposure, however as it is a highly complex matrix, the sample preparation is a critical step before the instrumental analysis. The aim of this work was to develop a suitable meconium sample extraction technique using the advantages of salting-out assisted liquid-liquid extraction (SALLE) and using only MS-friendly organic ammonium salts. We further developed and validated liquid chromatography tandem-mass spectrometry method for the determination of 'traditional' stimulants (methamphetamine, amphetamine, MDMA) and cathinones (mephedrone, methylenedioxypyrovalerone (MDPV), α-pyrrolidinopentiophenone (α-PVP), methylone, butylone, flephedrone, and naphyrone). Matrix-matched calibration was prepared in the concentration range 10-2000 ng/g. The limits of quantification were determined as 10 ng/g, recoveries ranged from 48.2% to 94.3% and the matrix effect was between 60.2% and 101.4%. Accuracy (86.1-114.5%) and precision (4.9-14.9%) were determined and all validation criteria were met for all analytes except for naphyrone. Finally, our analytical method was tested on a set of real meconium samples, which were found positive for amphetamine, methamphetamine and methylone, thus demonstrating the validity of the method.

Near-fatal Intoxication with the "New" Synthetic Opioid U-47700: The First Reported Case in the Czech Republic.

Recreational use of the potent synthetic opioid 3,4- dichloro-N-(2-(dimethylamino)cyclohexyl)-N-methylbenzamide (U-47700) is rising, accompanied by increasingly frequent cases of serious intoxication. This article reports a case of near-fatal U-47700 intoxication. A man was found unconscious (with drug powder residues). After 40 h in hospital (including 12 h of supported ventilation), he recovered and was discharged. Liquid chromatography/high-resolution mass spectrometry (LC/HRMS) or gas chromatography/mass spectrometry (GC/MS) were used to detect and quantify substances in powders, serum and urine. Powders contained U-47700 and two synthetic cannabinoids. Serum and urine were positive for U-47700 (351.0 ng/mL), citalopram (

Behavioral and Pharmacokinetic Profile of Indole-Derived Synthetic Cannabinoids JWH-073 and JWH-210 as Compared to the Phytocannabinoid Δ9-THC in Rats.

Synthetic cannabinoid compounds are marketed as "legal" marijuana substitutes, even though little is known about their behavioral effects in relation to their pharmacokinetic profiles. Therefore, in the present study we assessed the behavioral effects of systemic treatment with the two synthetic cannabinoids JWH-073 and JWH-210 and the phytocannabinoid Δ9-THC on locomotor activity, anxiety-like phenotype (in the open field) and sensorimotor gating (measured as prepulse inhibition of the acoustic startle response, PPI), in relation to cannabinoid serum levels. Wistar rats were injected subcutaneously (sc.) with JWH-073 (0.1, 0.5, or 5 mg/kg), JWH-210 (0.1, 0.5, or 5 mg/kg), Δ9-THC (1 or 3 mg/kg) or vehicle (oleum helanti) in a volume of 0.5 ml/kg and tested in the open field and PPI. Although JWH-073, JWH-210, Δ9-THC (and its metabolites) were confirmed in serum, effects on sensorimotor gating were absent, and locomotor activity was only partially affected. Δ9-THC (3 mg/kg) elicited an anxiolytic-like effect as suggested by the increased time spent in the center of the open field (p < 0.05). Our results further support the potential anxiolytic-like effect of pharmacological modulation of the endocannabinoid system.

Novel electrophoretic acetonitrile-based stacking for sensitive monitoring of the antiepileptic drug perampanel in human serum.

Perampanel is a novel antiepileptic drug used in paediatric patients. Existing methods that determine serum perampanel are of limited practicability. We developed a novel capillary electrophoresis (CE) method using a new version of acetonitrile stacking for on-line sample pre-concentration, and fluorescence detection (FD). CE separations were performed in a fused-silica capillary where the electroosmotic flow was reduced by coating the inner surface using a INST coating solution. The optimised background electrolyte composition was 50 mM chloroacetic acid with addition of 0.5% m/v polyvinylalcohol (pH 2.15) and separation was driven by application of positive voltage + 30 kV. Serum samples (25 µL) treated by the addition of acetonitrile in a ratio of 1:3 v/v were each injected into the capillary at a large volume that corresponded to the length (129 mm) of the sample zone (hydrodynamic pressure impulse 6000 mbars). Acetonitrile stacking is based on the forcing the sample zone out of the capillary with simultaneous application of the separation voltage. Under such conditions, the enhancing factor achieves the value 57 for peak area compared to the small sample injection length (3.2 mm, hydrodynamic pressure impulse 150 mbar.s). A fluorescence detector with a broad excitation filter (240-400 nm) and an emission filter (495 nm) was used for visualisation of the native fluorescence of perampanel. The calibration dependence of the method was linear (in the range of 10-1000 ng mL-1), with adequate accuracy (99.8-103.3 %) and precision (13.1%). LOD and LOQ for perampanel were 2.9 ng mL-1 and 9.5 ng mL-1, respectively. Clinical applicability was validated using serum samples from patients treated with perampanel and the results corresponded with reference LC-MS/MS values. Our method offers a promising alternative for determining serum perampanel with several advantages. In particular, the low quantity of serum (25 µL) required means that testing can be performed on samples obtained for monitoring other antiepileptic medications, and thus reduces the test-burden on paediatric patients.

Pharmacokinetic and behavioural profile of THC, CBD, and THC+CBD combination after pulmonary, oral, and subcutaneous administration in rats and confirmation of conversion in vivo of CBD to THC.

Metabolic and behavioural effects of, and interactions between Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD) are influenced by dose and administration route. Therefore we investigated, in Wistar rats, effects of pulmonary, oral and subcutaneous (sc.) THC, CBD and THC+CBD. Concentrations of THC, its metabolites 11-OH-THC and THC-COOH, and CBD in serum and brain were determined over 24h, locomotor activity (open field) and sensorimotor gating (prepulse inhibition, PPI) were also evaluated. In line with recent knowledge we expected metabolic and behavioural interactions between THC and CBD. While cannabinoid serum and brain levels rapidly peaked and diminished after pulmonary administration, sc. and oral administration produced long-lasting levels of cannabinoids with oral reaching the highest brain levels. Except pulmonary administration, CBD inhibited THC metabolism resulting in higher serum/brain levels of THC. Importantly, following sc. and oral CBD alone treatments, THC was also detected in serum and brain. S.c. cannabinoids caused hypolocomotion, oral treatments containing THC almost complete immobility. In contrast, oral CBD produced mild hyperlocomotion. CBD disrupted, and THC tended to disrupt PPI, however their combination did not. In conclusion, oral administration yielded the most pronounced behavioural effects which corresponded to the highest brain levels of cannabinoids. Even though CBD potently inhibited THC metabolism after oral and sc. administration, unexpectedly it had minimal impact on THC-induced behaviour. Of central importance was the novel finding that THC can be detected in serum and brain after administration of CBD alone which, if confirmed in humans and given the increasing medical use of CBD-only products, might have important legal and forensic ramifications.

Quantification of paracetamol and 5-oxoproline in serum by capillary electrophoresis: Implication for clinical toxicology.

High anion gap metabolic acidosis frequently complicates acute paracetamol overdose and is generally attributed to lactic acidosis or compromised hepatic function. However, metabolic acidosis can also be caused by organic acid 5-oxoproline (pyroglutamic acid). Paracetamol's toxic intermediate, N-acetyl-p-benzoquinoneimine irreversibly binds to glutathione and its depletion leads to subsequent disruption of the gamma glutamyl cycle and an excessive 5-oxoproline generation. This is undoubtedly an underdiagnosed condition because measurement of serum 5-oxoproline level is not readily available. A simple, cost effective, and fast capillary electrophoresis method with diode array detection (DAD) for simultaneous measurement of both paracetamol (acetaminophen) and 5-oxoproline in serum was developed and validated. This method is highly suitable for clinical toxicology laboratory diagnostic, allowing rapid quantification of acidosis inducing organic acid 5-oxoproline present in cases of paracetamol overdose. The calibration dependence of the method was proved to be linear in the range of 1.3-250µgmL-1, with adequate accuracy (96.4-107.8%) and precision (12.3%). LOQ equaled 1.3µgmL-1 for paracetamol and 4.9µgmL-1 for 5-oxoproline.

Two Cases of Non-fatal Intoxication with a Novel Street Hallucinogen: 3-Methoxy-Phencyclidine.

3-Methoxy-phencyclidine (3-MeO-PCP) is a structural derivative of the dissociative hallucinogen phencyclidine (PCP). Although PCP toxicity is well documented, little is known about this new psychoactive substance despite being available on the black market even in central Europe. The objective of this case report is to present clinical and laboratory data of analytically confirmed non-fatal intoxication of two subjects with 3-MeO-PCP. A preliminary assessment of potential metabolites excreted into urine was enabled using the liquid chromatography high resolution mass spectrometric method.

Gabapentin, Pregabalin and Vigabatrin Quantification in Human Serum by GC-MS After Hexyl Chloroformate Derivatization.

A simple, sensitive and robust method for simultaneous determination of antiepileptic drugs (gabapentin, pregabalin and vigabatrin) in human serum using GC-MS was developed and validated for clinical toxicology purposes. This method employs an emerging class of derivatization agents - alkyl chloroformates allowing the efficient and rapid derivatization of both the amino and carboxylic groups of the tested antiepileptic drugs within seconds. The derivatization protocol was optimized using the Design of Experiment statistical methodology, and the entire sample preparation requires less than 5 min. Linear calibration curves were obtained in the concentration range from 0.5 to 50.0 mg/L, with adequate accuracy (97.9-109.3%) and precision (<12.1%). The method was successfully applied to quantification of selected γ-aminobutyric acid analogs in the serum of patients in both therapeutic and toxic concentration ranges.

Simultaneous Determination of Methanol, Ethanol and Formic Acid in Serum and Urine by Headspace GC-FID.

A simple, cost-effective headspace gas chromatography (GC) method coupled with GC with flame ionization detection for simultaneous determination of methanol, ethanol and formic acid was developed and validated for clinical and toxicological purposes. Formic acid was derivatized with an excess of isopropanol under acidic conditions to its volatile isopropyl ester while methanol and ethanol remained unchanged. The entire sample preparation procedure is complete within 6 min. The design of the experiment (the face-centered central composite design) was used for finding the optimal conditions for derivatization, headspace sampling and chromatographic separation. The calibration dependences of the method were quadratic in the range from 50 to 5,000 mg/L, with adequate accuracy (89.0-114.4%) and precision (<12%) in the serum. The new method was successfully used for determination of selected analytes in serum samples of intoxicated patients from among those affected by massive methanol poisonings in the Czech Republic in 2012.

Identification and quantification of acidosis inducing metabolites in cases of alcohols intoxication by GC-MS for emergency toxicology.

A simple, cost effective, and fast gas chromatography method with mass spectrometry detection (GC-MS) for simultaneous measurement of formic acid, glycolic acid, methoxyacetic acid, ethoxyacetic acid and 2-hydroxyethoxyacetic acid in serum and urine was developed and validated. This multi-analyte method is highly suitable for clinical and emergency toxicology laboratory diagnostic, allowing identification and quantification of five most common acidosis inducing organic acids present in cases of alcohol intoxication. Furthermore, when patients are admitted to emergency unit at late stage of toxic alcohol intoxication, the concentration of parent compound may be already low or not detectable. This new method employs a relatively less used class of derivatization agents - alkyl chloroformates, allowing the efficient and rapid derivatization of carboxylic acids within seconds. The entire sample preparation procedure is completed within 5 min. The optimal conditions of derivatization procedure have been found using chemometric approach (design of experiment). The calibration dependence of the method was proved to be quadratic in the range of 25-3000 mg L(-1), with adequate accuracy (97.3-108.0%) and precision (<12.8%). The method was successfully applied for identification and quantification of the selected compounds in serum of patients from emergency units.