Identification of phytolaccosides in biological samples from pokeweed intoxication patients using liquid chromatography-tandem mass spectrometry.

In Phytolaccaceae family, Phytolacca americana L. (American pokeweed) and P. esculenta Van Houtte (Chinese pokeweed) are the two representative species among the genus. Pokeweeds have triterpenoid saponins as toxic compounds in every part of the plant. The saponins phytolaccoside A, B, D, E, and G were isolated from P. americana, and esculentoside H, J, L, K, M, I, and N were isolated from P. esculenta. Along with saponins, their aglycones (phytolaccagenin, phytolaccagenic acid, esculentic acid and jaligonic acid) were also isolated from P. americana and P. esculenta. Two people who unknowingly ate misidentified pokeweed plant roots were transferred to the emergency room. Urine and gastric content after irrigation were collected from the first patient (patient 1), and blood and urine were collected from the second patient (patient 2). The samples were analyzed to identify toxic substances with liquid chromatography-tandem mass spectrometry (LC-MS/MS). In the blood sample, 1.9 ng/mL of esculentoside A and 1.5 ng/mL of esculentoside C were detected, while the concentration of esculentoside B and H were below the LLOQ. In gastric contents and ingested roots, esculentoside A, B, C, and H were identified. Esculentoside A, C, and H were identified in the urine of patient 1, and esculentoside A and C were identified in the urine sample of patient 2. The developed analytical method was validated for parameters such as linearity, limit of detection, precision, accuracy, matrix effect, recovery, and process efficiency, and they showed clear and unbiased results.

Determination of robenidine residues in chicken muscle by high performance liquid chromatography with ultraviolet detection.

A simple, robust and reliable method for the determination of residual robenidine in chicken muscle using high performance liquid chromatography with ultraviolet (UV) detection was developed and validated according to the Codex Alimentarius Commission guidelines. Chicken muscle was extracted by acetonitrile/formic acid (98:2, v/v) and defatted with hexane. Analytes were isocratically separated on a Luna C18 column (4.6 × 150 mm, 5 µm) using 70 % methanol in water containing 0.1 % trifluoroacetic acid at a flow rate of 1.0 mL/min at 30 °C. UV detection was performed at 312 nm. The method was validated by assessing performance parameters including selectivity, linearity, limit of quantification (LOQ), precision, accuracy, recovery, stability and robustness. A calibration curve that was constructed over 0.05-0.5 µg/g showed correlation coefficients of more than 0.999. The intra- and inter-day precisions (as coefficient of variation) were 1.45-3.32 and 2.63-4.99 %, respectively. The intra- and inter-day accuracies were 99.4-105.3 and 98.3-101.6 %, respectively. The recoveries were in the range of 76.6-81.8 % and the LOQ was 0.05 µg/g. The developed method showed suitable performance for the determination of robenidine residues in chicken muscle.

Distribution of cyanide in heart blood, peripheral blood and gastric contents in 21 cyanide related fatalities.

This paper presents 21 cases related to cyanide intoxication by oral ingestion. Cyanide concentrations in biological specimens are especially different from the type of postmortem specimens, and very important in interpreting the cause of death in postmortem forensic toxicology. Besides the detection of cyanide in autopsy specimens, the autopsy findings were unremarkable. Biological samples (0.2mL or equal to less than 10µg of cyanide) were analyzed colorimetrically for cyanide. In a series of 21 cyanide fatalities, the concentration ranges (mean±SD) of cyanide in heart blood, peripheral blood and gastric contents were 0.1-248.6mg/L (38.1±56.6mg/L), 0.3-212.4mg/L (17.1±45.1mg/L) and 2.0-6398.0mg/kg (859.0±1486.2mg/kg), respectively. The ranges of the heart/peripheral blood concentration ratio and gastric contents/peripheral blood concentration ratio were 0.3-10.6 (mean 3.4) and 3.4-402.4 (mean 86.0), respectively. From the difference of cyanide concentration and the concentration ratio of cyanide in different types of postmortem specimens, the possibility of the postmortem redistribution of cyanide and death by oral ingestion of cyanide could be confirmed. We reported cyanide fatal cases along with a review of literature.

Development and validation of a liquid chromatography-tandem mass spectrometry method for the determination of goserelin in rabbit plasma.

A rapid and sensitive liquid chromatography-electrospray ionization tandem mass spectrometry method (LC-ESI-MS/MS) was developed and validated for the determination of goserelin in rabbit plasma. Various parameters affecting plasma sample preparation, LC separation, and MS/MS detection were investigated, and optimized conditions were identified. Acidified plasma samples were applied to Oasis((R)) HLB solid-phase extraction (SPE) cartridges. Extracted samples were evaporated under a stream of nitrogen and then reconstituted with 100microL mobile phase A. The separation was achieved on a Capcell-Pak C18 (2.0mmx150mm, 5microm, AQ type) column with a gradient elution of solvent A (0.05% acetic acid in deionized water/acetonitrile=85/15; v/v) and solvent B (acetonitrile) at a flow rate of 250microL/min. The LC-MS/MS system was equipped with an electrospray ion source operating in positive ion mode. Multiple-reaction monitoring (MRM) of the precursor-product ion transitions consisted of m/z 635.7-->m/z 607.5 for goserelin and m/z 424.0-->m/z 292.1 for cephapirin (internal standard). The proposed method was validated by assessing specificity, linearity, limit of quantification (LOQ), intra- and inter-day precision and accuracy, recovery, and stability. Linear calibration curves were obtained in the concentration range of 0.1-20ng/mL (the correlation coefficients were above 0.99). The LOQ of the method was 0.1ng/mL. Results obtained from the validation study of goserelin showed good accuracy and precision at concentrations of 0.1, 1, 5, 10, and 20ng/mL. The validated method was successfully applied to a pharmacokinetic study of goserelin after a single subcutaneous injection of 3.6mg of goserelin in healthy white rabbits.

Comparison between evaporative light scattering detection and charged aerosol detection for the analysis of saikosaponins.

Saikosaponins are triterpene saponins derived from the roots of Bupleurum falcatum L. (Umbelliferae), which has been traditionally used to treat fever, inflammation, liver diseases, and nephritis. It is difficult to analyze saikosaponins using HPLC-UV due to the lack of chromophores. Therefore, evaporative light scattering detection (ELSD) is used as a valuable alternative to UV detection. More recently, a charged aerosol detection (CAD) method has been developed to improve the sensitivity and reproducibility of ELSD. In this study, we compared CAD and ELSD methods in the simultaneous analysis of 10 saikosaponins, including saikosaponins-A, -B(1), -B(2), -B(3), -B(4), -C, -D, -G, -H and -I. A mixture of the 10 saikosaponins was injected into the Ascentis Express C18 column (100 mm x 4.6 mm, 2.7 microm) with gradient elution and detection with CAD and ELSD by splitting. We examined various factors that could affect the sensitivity of the detectors including various concentrations of additives, pH and flow rate of the mobile phase, purity of nitrogen gas and the CAD range. The sensitivity was determined based on the signal-to-noise ratio. The best sensitivity for CAD was achieved with 0.1 mM ammonium acetate at pH 4.0 in the mobile phase with a flow rate of 1.0 mL/min, and the CAD range at 100 pA, whereas that for ELSD was achieved with 0.01% acetic acid in the mobile phase with a flow rate at 0.8 mL/min. The purity of the nitrogen gas had only minor effects on the sensitivities of both detectors. Finally, the sensitivity for CAD was two to six times better than that of ELSD. Taken together, these results suggest that CAD provides a more sensitive analysis of the 10 saikosaponins than does ELSD.