Development and Validation of a Capillary Zone Electrophoresis-Tandem Mass Spectrometry Method for Simultaneous Quantification of Eight ß-Lactam Antibiotics and Two ß-Lactamase Inhibitors in Plasma Samples.

Monitoring plasma concentrations of ß-lactam antibiotics is crucial, particularly in critically ill patients, where variations in concentrations can lead to treatment failure or adverse events. Standardized antimicrobial regimens may not be effective for all patients, especially in special groups with altered physiological parameters. Pharmacokinetic/pharmacodynamic (PK/PD) studies highlight the time-dependent antibacterial activity of these antibiotics, emphasizing the need for personalized dosing. Therapeutic drug monitoring (TDM) is essential, requiring rapid and accurate analytical methods for precise determination of drugs in biological material (typically plasma or serum). This study presents a novel capillary zone electrophoresis-tandem mass spectrometry (CZE-MS/MS) method designed for the simultaneous quantification of five penicillin antibiotics, two cephalosporins, one carbapenem, and two ß-lactamase inhibitors in a single run. The method involves a simple sample pretreatment-precipitation with organic solvent-and has a run time of 20 min. Optimization of CZE separation conditions revealed that 20 mM ammonium hydrogen carbonate (NH4HCO3) serves as the optimal background electrolyte (BGE). Positive electrospray ionization (ESI) mode, with isopropyl alcohol (IP)/10 mM ammonium formate water solution (50/50, v/v) as the sheath liquid, was identified as the optimal condition for MS detection. Method validation according to the Food and Drug Administration (FDA) guideline for development of bioanalytical methods demonstrated satisfactory selectivity, linearity, recovery, robustness, and stability. The method's practicality was evaluated using the Blue Applicability Grade Index (BAGI), yielding a score of 77.5. Moreover, the greenness of the proposed method was evaluated by two commonly used metric tools-Analytical GREEnness (AGREE) and Green Analytical Procedure Index (GAPI). The developed CZE-MS/MS method offers a practical and reliable approach for quantifying a broad spectrum of ß-lactam antibiotics in plasma. Its ability to simultaneously quantify multiple analytes in a single run, coupled with a straightforward sample pretreatment, positions it as a valuable and prospective tool for TDM in critically ill patients.

Population Pharmacokinetic Analysis Proves Superiority of Continuous Infusion in PK/PD Target Attainment with Oxacillin in Staphylococcal Infections.

Considering its very short elimination half-life, the approved oxacillin dosage might not be sufficient to maintain the pharmacokinetic/pharmacodynamics (PK/PD) target of time-dependent antibiotics. This study aimed to describe the population pharmacokinetics of oxacillin and to explore the probability of PK/PD target attainment by using various dosing regimens with oxacillin in staphylococcal infections. Both total and unbound oxacillin plasma concentrations retrieved as a part of routine therapeutic drug-monitoring practice were analyzed using nonlinear mixed-effects modeling. Monte Carlo simulations were used to generate the theoretical distribution of unbound oxacillin plasma concentration-time profiles at various dosage regimens. Data from 24 patients treated with oxacillin for staphylococcal infection have been included into the analysis. The volume of distribution of oxacillin in the population was 11.2 L, while the elimination rate constant baseline of 0.73 h-1 increased by 0.3 h-1 with each 1 mL/s/1.73 m2 of the estimated glomerular filtration rate (eGFR). The median value of oxacillin binding to plasma proteins was 86%. The superiority of continuous infusion in achieving target PK/PD values was demonstrated and dosing according to eGFR was proposed. Daily oxacillin doses of 9.5 g, 11 g, or 12.5 g administered by continuous infusion have been shown to be optimal for achieving target PK/PD values in patients with moderate, mild, or normal renal function, respectively.

Meropenem population pharmacokinetics and model-based dosing optimisation in patients with serious bacterial infection.

OBJECTIVES: The objective of this study was to develop a population pharmacokinetic model of meropenem in a heterogeneous population of patients with a serious bacterial infection in order to propose dosing optimisation leading to improved achievement of the pharmacokinetic/pharmacodynamic (PK/PD) target. METHODS: A total of 174 meropenem serum levels obtained from 144 patients during therapeutic drug monitoring were analysed using a non-linear mixed-effects modelling approach and Monte Carlo simulation was then used to compare various dosing regimens in order to optimise PK/PD target attainment. RESULTS: The meropenem volume of distribution of the patient population was 54.95 L, while clearance started at 3.27 L/hour and increased by 0.91 L/hour with each 1 mL/s/1.73 m2 of estimated glomerular filtration rate. Meropenem clearance was also 0.31 L/hour higher in postoperative patients with central nervous system infection. Meropenem administration by continuous infusion showed a significantly higher probability of attaining the PK/PD target than a standard 30 min infusion (95.3% vs 49.5%). CONCLUSIONS: A daily meropenem dose of 3 g, 6 g and 10.5 g administered by continuous infusion was shown to be accurate for patients with moderate to severe renal impairment, normal renal function to mild renal impairment and augmented renal clearance, respectively.

Fatal intoxication by intravenous injection of castor bean (Ricinus communis L.) extract-a case study.

A case report of a 25-year-old man who committed suicide by intravenous injection himself of an aqueous home-made castor bean extract is presented. The patient was hospitalized and treated symptomatically and was released at its own request fourth day after intoxication. The next day, the patient's condition deteriorated, and he died 6 days after intoxication even though he was given medical care. Case history, autopsy, and toxicological investigation of ante- and post-mortem collected materials are described. Blood and urine collected from the patient ante-mortem and other several biological materials (namely blood from the upper and lower limb, blood from the right and left ventricle, pericardial fluid, vitreous humour, liver, kidney, and spleen) were collected post-mortem during autopsy. Liquid-liquid extraction procedure followed by high-performance liquid chromatography tandem mass spectrometry analysis for identification and determination of ricinine as a biomarker of ricin/castor seed intoxication was developed and validated. The method was applied on analysis of collected ante- and post-mortem biological materials. The post-mortem contents of ricinine in organs (namely the liver, kidney, and spleen) are firstly reported. The obtained results indicated approximately uniform distribution of ricinine (concentration level about 1 ng mL-1) in the body after death. In addition, the GC-MS method was also applied for the analysis of extract of castor seed and the patient's urine, to demonstrate alternative possibility for identification of ricinine for clinical and forensic purposes.

Laser ablation inductively coupled plasma mass spectrometry imaging: A personal identification based on a gunshot residue analysis on latent fingerprints.

A new laser ablation inductively coupled plasma mass spectrometry imaging (LA-ICP-MSI) method has been developed to visualize latent fingerprint of suspect persons possibly related to a criminal offence committed with a gun. Metallic impurities and metallic gunshot residues (GSRs) adhered on a latent fingerprint can link biometric information and shooting. The identification and spatial distribution of characteristic gunshot-related metals (Cu, Zn, Sb, Ba, Hg, Pb) was studied in detail. Observed limits of detection for the corresponding metals were below 0.3 ng cm-2. The distributions of the selected metals were simply transferred to images of fingerprints that can reveal a person somehow manipulating with a gun while the presence of characteristic and consistent GSR particles provided the evidence of the shooting. LA-ICP-MSI has been proved to be a unique tool in dactyloscopic identification of a suspect person from latent and commonly visualized fingerprints.

Simultaneous determination of designer benzodiazepines in human serum using non-aqueous capillary electrophoresis - Tandem mass spectrometry with successive multiple ionic - Polymer layer coated capillary.

A novel non-aqueous capillary electrophoresis - tandem mass spectrometry method for the simultaneous separation, identification and quantification of nine designer benzodiazepines (bentazepam, etizolam, deschloroetizolam, diclazepam, flubromazepam, flubromazolam, nimetazepam, phenazepam, and pyrazolam) was developed. A non-aqueous running electrolyte consisting of 25mM ammonium acetate with 100mM trifluoroacetic acid in acetonitrile was used. The separation was carried out using a semipermanent coated capillary (successive multiple ionic-polymer coating) with a strong anodic electroosmotic flow at a negative separation voltage within twelve minutes. Electrospray ionization with a triple quadrupole mass spectrometry was utilized for the identification and quantification of selected designer benzodiazepines in a positive ionization mode. The developed method was validated and applied on the analysis of spiked serum sample following a simple liquid-liquid extraction. The LODs of the designer benzodiazepines were between 1.5 and 15.0ngmL-1.

Pre-caecal digestible phosphorus in maize and wheat for broiler chickens.

1. The objective of this study was to determine the coefficient of pre-caecal digestion of P in maize (3.9 g/kg of total P, 0.83 g/kg of phytate P, 138 FTU [phytase units]/kg) and wheat (3.17 g/kg of total P, 1.94 g/kg of phytate P, 666 FTU/kg) in broilers according to the WPSA protocol. 2. For the diets, monosodium phosphate was used as an additional P supplement. Two sets of diets containing 200, 460 and 740 g/kg of wheat or 200, 500 and 740 g/kg of maize were formulated. A total of 288 21-d-old male broilers (Ross 308) were assigned to 24 cages (8 birds per cage) and the 6 test diets were assigned to cages. The coefficient of pre-caecal digestion of P was determined by the indicator method and linear regression. 3. In both ingredients, pre-caecal digestible P increased linearly with increasing inclusion levels of maize or wheat (P < 0.05). The coefficients of digestion of pre-caecal P were estimated to be 0.18 for wheat and 0.33 for maize.

Analysis of selected designer benzodiazepines by ultra high performance liquid chromatography with high-resolution time-of-flight mass spectrometry and the estimation of their partition coefficients by micellar electrokinetic chromatography.

A new ultra high performance liquid chromatography with electrospray ionization time of flight mass spectrometry method for the selective and sensitive separation, identification, and determination of selected designer benzodiazepines (namely, pyrazolam, phenazepam, etizolam, flubromazepam, diclazepam, deschloroetizolam, bentazepam, nimetazepam, and flubromazolam) in human serum was developed. The separation of the studied designer benzodiazepines was achieved on C18 chromatographic column using gradient elution within 6 min without any significant matrix interferences. Liquid-liquid extraction with butyl acetate was applied for serum samples cleanup and preconcentration of studied designer benzodiazepines. The method was validated in terms of linearity, limit of detection, limit of quantification, matrix effects, specificity, precision, accuracy, recovery, and sample stability. The limit of detection values were 0.10-0.15 ng/mL. The method was applied to a spiked serum sample to demonstrate its applicability for systematic toxicology analysis. Furthermore, a capillary chromatographic method with micellar electrokinetic chromatography was used for the estimation of partition coefficients of studied designer benzodiazepines as important parameters to evaluate their pharmacological and toxicological properties.

Enantioseparation of d,l-2-hydroxyglutaric acid by capillary electrophoresis with tandem mass spectrometry-Fast and efficient tool for d- and l-2-hydroxyglutaracidurias diagnosis.

A novel capillary electrophoresis-tandem mass spectrometry method for the enantioseparation and identification of 2-hydroxyglutaric acid enantiomers without derivatization for clinical purposes was described. Vancomycin chloride was used as an efficient chiral selector for the discrimination of 2-hydroxyglutaric acid enantiomers by capillary electrophoresis employed complete capillary filling method. The obtained resolution was 2.05. Hyphenation of CE with tandem mass spectrometry allows a reliable identification of separated enantiomers as well as their quantification. The method was validated and applied for the separation, identification and determination of 2-hydroxyglutaric enantiomers in urine samples obtained from healthy patients and two urine samples obtained from child patients suffering from high urine excretion of 2-hydroxyglutaric acid. Abnormal excretion of d-hydroxyglutaric acid was found in both child urine samples (104.5±2.1 and 2200.0±12.6mmol/mol of creatinine, respectively). The limits of detection for d- and l-hydroxyglutaric acid were 31 and 38nmol/L, respectively.

Determination of selected synthetic cannabinoids and their metabolites by micellar electrokinetic chromatography--mass spectrometry employing perfluoroheptanoic acid-based micellar phase.

Perfluoroheptanoic acid was employed as a volatile micellar phase in background electrolyte for micellar electrokinetic chromatography-tandem mass spectrometry separation and determination of 15 selected naphthoyl- and phenylacetylindole- synthetic cannabinoids and main metabolites derived from JWH-018, JWH-019, JWH-073, JWH-200 and JWH-250. The influence of concentration of perfluoroheptanoic acid in background electrolytes on the separation was studied as well as the influence of perfluoroheptanoic acid on mass spectrometry detection. The background electrolyte consisted of 75 mM perfluoroheptanoic acid, 150 mM ammonium hydroxide pH 9.2 with 10% (v/v) propane-2-ol allowed micellar electrokinetic chromatography separation together with mass spectrometry identification of the studied parent synthetic cannabinoids and their metabolites. The limits of detection of studied synthetic cannabinoids and metabolites were in the range from 0.9 ng/mL for JWH-073 to 3.0 ng/mL for JWH-200 employing liquid-liquid extraction. The developed method was applied on the separation and identification of studied analytes after liquid-liquid extraction of spiked urine and serum samples to demonstrate the potential of the method applicability for forensic and toxicological purposes.

The empirical comparison of cyclofructans and cyclodextrins as chiral selectors in capillary electrophoretic separation of atropisomers of R,S-1,1'-binaphthalene-2,2'-diyl hydrogen phosphate.

Native cyclofructans and their isopropyl derivatives were studied as chiral selectors in capillary electrophoresis and compared with α- and ß-cyclodextrin. R,S-1,1'-Binaphthalene-2,2'-diyl hydrogen phosphate was used as a model chiral compound. The empirical observation of the enantioselectivity of native cyclofructans and isopropyl derivatives of cyclofructans was described and compared with the cyclodextrins. The influence of methanol and acetonitrile, as the most commonly used organic solvents, and sodium dodecyl sulfate as a micelle forming additive on the separation of R,S-1,1'-binaphthalene-2,2'-diyl hydrogen phosphate atropisomers was achieved. The different enantiorecognition abilities resulting from unlike interaction mechanism with R,S-1,1'-binaphthalene-2,2'-diyl hydrogen phosphate were observed for the studied cyclodextrins and cyclofructans, especially when methanol or sodium dodecyl sulfate were used as modifiers of the separation conditions.

Enantiomeric separation of 1,3-dimethylamylamine by capillary electrophoresis with indirect UV detection using a dual-selector system.

The CE method employing an indirect UV detection for the enantioseparation of 1,3-dimethylamylamine (DMAA), widely used in various preworkout and dietary supplements labeled as a constituent of geranium extract has been developed. The dual-selector system consisting of negatively charged sulfated α-CD (1.1% w/v) and sulfated ß-CD (0.2% w/v) in 5 mM phosphate/Tris buffer (pH 3.0) containing the addition of 10 mM benzyltriethylammonium chloride (BTEAC) as the chromophoric additive was used for the enantiomeric separation of DMAA stereoisomers with the LODs in the range of 7.82-9.24 µg/mL. The method was partly validated and applied for the determination of the stereoisomeric composition of DMAA in commercial dietary supplements to verify the potential natural origin of DMAA.

Utilization of micellar electrokinetic chromatography-tandem mass spectrometry employed volatile micellar phase in the analysis of cathinone designer drugs.

A micellar electrokinetic chromatography method with tandem mass spectrometry has been developed for the selective separation, identification and determination of twelve new designer drugs from the group of synthetic cathinones. Ammonium salt of perfluorooctanoic acid at various concentrations as a volatile background electrolyte (BGE) to create micellar phase was studied for separation of selected synthetic cathinones with direct tandem mass spectrometry without significant loss of detection sensitivity. The optimized BGE contained 100 mM perfluorooctanoic acid with 200 mM ammonium hydroxide providing acceptable resolution of studied drugs in the MEKC step. In order to minimize interferences with matrix components and to preconcentrate target analytes, solid phase extraction was introduced as a clean-up step. The method was linear in the concentration range of 10-5000 ng mL(-1) and the limits of detection were in the range of 10-78 ng mL(-1). The method was demonstrated to be specific, sensitive, and reliable for the systematic toxicological analysis of these derivatives in urine samples.

HPLC-ED of low-molecular weight brominated phenols and tetrabromobisphenol A using pretreated carbon fiber microelectrode.

Electrochemically pretreated carbon fiber microelectrode was used to develop a simple, fast and sensitive HPLC-ECD method for the determination of brominated phenols. In addition to simple mono-, di- and tri-bromophenols (4-bromophenol, 2,4-dibromophenol, 2,6-dibromophenol, 2,4,6-tri-bromophenol) the possibility of electrochemical detection of 3,3',5,5'-tetrabromobisphenol A in oxidation mode is reported for the first time. The isocratic separation was achieved within 14 min using ternary mobile phase consisting of 50mM-phosphate buffer (pH 3.5), acetonitrile and methanol (35/15/50, v/v), and detection potential of E=+1450 mV (vs. Ag/AgCl). The carbon fiber microelectrode permitted to use high anodic potentials (up to +1800 mV vs. Ag/AgCl), the optimum analytical response was achieved at +1450 mV vs. Ag/AgCl. The limits of detection (LOD) for the studied analytes were within the range of 1.8-56.6 ng mL(-1). The developed method was applied to determination of brominated phenols in spiked water samples. Furthermore, after simple extraction with methyl tert-butyl ether, it was possible to quantify tetrabromobisphenol A (TBBA) in a piece of CRT monitor plastic casing. The found amount of TBBA was 10.22 mg kg(-1) (±0.43).

Isopropyl derivative of cyclofructan 6 as chiral selector in liquid chromatography and capillary electrophoresis.

Cyclofructans and preferentially their derivatives can serve as chiral selectors for the separation of different enantiomers/atropisomers. Moreover, the strong ionophoric nature of the 18-crown-6 ether core of cyclofructan 6 for barium cations may be exploited to enhance or modify enantioselectivity. In this work isopropyl-cyclofructan-6 was used as a chiral selector for the separation of binaphthyl atropisomers in HPLC and CE. The data from both separation systems were compared with each other. While in HPLC the chiral selector was bonded to silica gel to afford a chiral stationary phase, in capillary electrophoresis it was freely mobile in the background electrolytes (BGE). This significant difference is reflected in the separation potential of the two separation systems. All five analytes could be baseline separated in HPLC (reversed phase mode) while only one derivative was baseline resolved in CE. This result was attributed to the more rigid nature of the immobilized chiral selector. Addition of Ba(2+) to the mobile phase or BGE improved chiral separations in both systems. The results may help to elucidate the interaction mechanism in these systems with cyclofructan derivatives and to gain some general knowledge of their separation potential.

Study on the use of boromycin as a chiral selector in capillary electrophoresis.

The first application of boromycin as a chiral selector in capillary electrophoresis is described. Given boromycin's insolubility in water, a non-aqueous background electrolyte based on methanol was used for enantiomeric discrimination of selected chiral primary amines (α-methylbenzylamine, R,S-tryptophanol, R,S-norepinephrine, R,S-octopamine, R,S-p-hydroxynorephedrine and R,S-2-amino-1-phenylethanol). A basic study of experimental conditions including the influence of boromycin concentration, the composition and concentration of background electrolyte and also the influence of different organic solvents was performed. The best separation condition was 75 mM Tris/50mM boric acid in methanol, pHws 9.0, with a positive separation voltage. The enantiomeric separation of the primary amines was achieved within 14 min with resolution values greater than 1.5 for the majority of the studied analytes.