High-throughput selected reaction monitoring liquid chromatography-mass spectrometry determination of methylphenidate and its major metabolite, ritalinic acid, in rat plasma employing monolithic columns. | LitMetric
Analytical Toxicology, Department of Population Medicine and Diagnostic Sciences, Cornell University, 927 Warren Drive, 14850, Ithaca, NY, USA.
Published: January 2003
AI Article Synopsis
Article Abstract
This work presents a high-throughput selected reaction monitoring (SRM) LC-MS method for the determination of methylphenidate (MPH), a central nervous stimulant, and its de-esterified metabolite, ritalinic acid (RA) in rat plasma samples. A separation of these two compounds was achieved in 15 s by employing a 3.5-ml/min flow-rate, a porous monolithic column and a TurboIonSpray source compatible with relatively high flow-rates. In addition, a relatively fast autosampler and a new data acquisition system resulted in a time lag of less than 17 s between consecutive injections. Overall, 768 protein-precipitated rat plasma samples (eight 96-well plates) containing both MPH and RA were analyzed within 3 h and 45 min. The partial method validation described in this report included an assessment of linearity, intra and inter-assay precision and accuracy, and method robustness. Deuterated internal standards for the target compounds, d(3)-MPH and d(5)-RA, were employed. The calibration curves ranged from 0.1 to 50 ng/ml for MPH and from 0.5 to 50 ng/ml for RA. The limit of quantification (LOQ) for MPH and RA was 0.1 and 0.5 ng/ml, respectively. For both analytes, the intra- and inter-assay precision (relative standard deviation, % C.V.) and accuracy (relative error) did not exceed 15% for the quality control samples (QCs) QC1, QC2 or QC3 (0.3, 1.5 and 40 ng/ml for MPH and 0.15, 15 and 40 ng/ml for RA) for either analyte and did not exceed 20% at the lower limit of quantitation (LOQ) level. No carry-over from the autosampler was detected. The retention times remained constant throughout the experiment. Baseline resolution of MPH and RA was consistently observed throughout the plates analyzed. The described method demonstrates the feasibility for employing monolithic HPLC columns to effect rapid bioanalytical SRM LC-MS analysis of representative biological samples.
Platypuses are a unique freshwater mammal native to eastern Australia. They are semi-aquatic, predominantly nocturnal, and nest in burrows dug into the banks of waterbodies. Quantifying nesting burrow characteristics is challenging due to the species' cryptic nature.
The present study evaluated the antioxidant and anti-inflammatory properties of (CA) fruit extract against bisphenol A (BPA)-induced ovarian injury in female Wistar rats. The antioxidant activity was estimated by the total antioxidant capacity (TAC) and superoxide radical (NBT) content. For the in vivo analyses, 24 animals were divided into the following 4 groups: the control group; the BPA group (50 mg/kg BW BPA for 30 days); the BPA + CA group (50 mg/kg BW BPA and 50 mg/kg BW CA); and the CA group (50 mg/kg BW CA).
Background: Hemorrhagic shock (HS) corresponds to absolute hypovolemia creating an imbalance between oxygen supply and consumption. This causes an impaired hemostasis, a systemic inflammatory response, and microvascular permeability which can lead to multiple organ failure (MOF). There is no specific treatment for the endothelial dysfunction that plays a major role in the evolution towards MOF.
Background: Chronic arterial hypertension restructures the vascular architecture of the brain, leading to a series of pathological responses that culminate in cerebral small-vessel disease. Pericytes respond dynamically to vascular challenges; however, how they manifest under the continuous strain of hypertension has not been elucidated.
Methods And Results: In this study, we characterized pericyte behavior alongside hypertensive states in the spontaneously hypertensive stroke-prone rat model, focusing on their phenotypic and metabolic transformation.
Chronic cerebral hypoperfusion (CCH) is a crucial mechanism causing vascular cognitive impairment (VCI). Choline is metabolized by gut microbiota into trimethylamine N-oxide (TMAO), a risk factor of cardiovascular diseases and cognitive impairment. However, the impact of choline-TMAO pathway on CCH-induced VCI is elusive.
