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Accumulating evidence suggests that amino acids are important indicators of nutritional and metabolic status. A high-resolution mass spectrometry method based on sequential window acquisition of all theoretical mass spectra acquisition was developed for the simultaneous determination of 16 amino acids in human plasma. Sample preparation by protein precipitation using a mixture of acetonitrile and formic acid was followed by a BEH Amide column. The superiority of this method was investigated by comparing it to time-of-flight scan and multiple reaction monitoring modes. The limit of detection in sequential window acquisition of all theoretical mass spectra mode for threonine, methionine, histidine, citrulline, and tryptophan is 0.1 ng on the column; for lysine and asparagine is 0.2 ng; for alanine, pyroglutamic acid, leucine, ornithine, and aspartate is 0.5 ng, for arginine is 1.0 ng; for glutamate and serine is 2.0 ng; for glutamine is 10.0 ng. This method was linear in the range 0.8-40 μg/mL for arginine, citrulline, glutamate, histidine, leucine, methionine, pyroglutamic acid, threonine, tryptophan; 2-100 μg/mL for asparagine, aspartate, lysine, ornithine, serine; and 4-200 μg/mL for alanine, glutamine with good accuracy and precision. Significantly different levels in 11 amino acids were observed between childhood and adulthood, representing the growth and development of individuals relating to the level of amino acids.

This study developed a detection method based on the strategy of HPLC/MS

Methotrexate, a folic acid antitumor drug, is widely used to treat childhood acute lymphoblastic leukemia. Therapeutic drug monitoring is crucial for adjusting the dosage of methotrexate according to its plasma concentration and reducing adverse effects. Micro-sampling strategies, like dried plasma spot, is an attractive but underutilized method that has the desired features of easy collection, storage, and transport, and overcomes known hematocrit issues in dried blood spot analysis. This study describes a dried plasma spot-based liquid chromatography-tandem mass spectrometry method for quantification of methotrexate. The assay showed good linearity over 30-2000 ng/mL (R

A simple sample preprocessing method was developed for the quantitative determination of amantadine (AMT) in human plasma by liquid chromatography-tandem mass spectrometry cubed (LC-MS

Valproic acid (VPA) dosing needs to be individualized for epilepsy patients through therapeutic drug monitoring (TDM). The patients must show up in the clinic at the therapeutic window time to venipuncture sample. Dried plasma spot (DPS) sampling is an alternative way to replace conventional venipuncture sampling. The aim of this study was to develop and validate a DPS-based liquid chromatography-tandem mass spectrometry (LC-MS/MS) method to monitor VPA in a routine clinical laboratory setting. We compare the DPS with the wet plasma method of clinical samples by LC-MS/MS. The method was linear over the dynamic range of 10-200 μg/ml (covering entire therapeutic range) with a correlation coefficient r2 ≥ 0.995. Both the DPS and wet plasma methods were fully validated for the accuracy, precision, recovery, and matrix effect. The analyte stability was examined under conditions mimicking the sample storage, transport, and analysis procedures. A clinical study with epilepsy patients receiving VPA (n = 35) showed that, after correction for hematocrit (HCT), plasma concentrations can be successfully calculated from the DPS quantification results. Passing-Bablok regression coefficients showed no proportional bias between estimated and measured plasma concentrations. Similar agreement was found by Bland-Altman plots. The dried sample could be mailed to the clinical lab to test by regular mail service. So DPS can be used for drug monitoring with self-sampling strategy at the patient's convenient time and place specially for ambulatory patients not attending a clinic.

A simple, highly selective and high throughput liquid chromatography tandem mass spectrometry cubed (LC/MS3) method was developed and validated for quantification of methotrexate in human plasma. The MS3 detection is a scanning mode of QTrap MS systems or ion trap MS systems. After simple protein precipitation with methanol, methotrexate and methotrexate-d3 were separated on an Agilent Poroshell 120 SB-C18 column (4.6 × 50 mm, 2.7 µm) using isocratic elution with a mobile phase consisting of 60% 0.1% formic acid in water and 40% 0.1% formic acid in acetonitrile. The flow rate is 0.8 mL/min. MS3 detection in positive ion mode used the MRM3 transitions at m/z 455.2→308.2→175.1 for quantification of methotrexate and m/z 458.2→311.2→175.1 for quantification of methotrexate-d3. The total run time was only 3 min for each sample. The LC/MS3 assay was linear in the concentration range 10–3000 ng/mL(R2 ≥ 0.995) and the intra- and inter-day accuracies were

To meet the increasing clinical needs for 25-hydroxyvitamin D3 (25OH-D3) detection, the development of an efficient and accurate high-performance liquid chromatography-mass spectrometry (HPLC-MS) method for plasma 25OH-D3 quantitation is important. Since 25OH-D3 is an endogenous compound, the lack of a plasma blank increases the difficulty of accurately quantifying 25OH-D3. Selection of a method suitable for clinical monitoring among various methods for endogenous compound quantification is necessary. Methyl tert butyl ether was chosen for the sample treatment in a liquid-liquid extraction protocol. Water as a blank matrix, 5% human serum albumin in water as a blank matrix, surrogate analyte and background subtraction were designed to address the problem of a deficiency of a plasma blank. Four liquid chromatography-tandem mass spectrometry methods were fully validated to verify the advantages and limitations owing to regulatory deficiencies for endogenous compound validation. All four methods met the criteria and could be used to monitor clinical samples. Overall 30 human plasma samples were quantified in parallel using the four methods. The difference between any two methods was

Objective: To explore the ameliorative effect and mechanism of Panax notoginseng (PNG) and Ticlid in treating early diabetic nephropathy (DN).Method: Fifty-eight patients were divided randomly into two groups, 28 patients of the Ticlid group treated with Ticlid 250 mg orally, once a day and 30 patients of the PNG group treated with PNG 8 ml in 250 ml of normal saline intravenous drip once a day. The therapeutic effect and relative indexes of the two groups were observed and compared.Results: After treatment, in both groups, the thromboxane B2 markedly reduced and was more prominent in the Ticlid group (P