A single-center prospective study of vitamin D levels and its supplementary effect in the first trimester

A rapid and sensitive high-performance liquid chromatography and electrospray tandem mass spectrometry method was developed and validated for estimation of fulvestrant in rabbit plasma using liquid-liquid extraction. The separation and quantification of fulvestrant were achieved by reverse-phase chromatography on a Sunfire C18 column (50 x 2.1. i.d., 3.5 microm) with isocratic elution at a flow rate of 300 microL/min using norethistrone as an internal standard from 500 microL plasma sample. The method was validated over the concentration range from 0.092 to 16.937 ng/mL with a lower limit of detection of 0.023 ng/mL. The intra-day and inter-day accuracy and precision were within 10%. The recovery was 85 and 90% for fulvestrant and norethistrone respectively. The chromatographic run time was only 2.5 min.

Improved liquid chromatography tandem mass spectrometry method for the determination of phenolic compounds in virgin olive oil

The study was conducted to evaluate the applicability of ultra high-performance liquid chromatography - tandem mass spectrometry method (UHPLC-MS/MS), establish the MS/MS detection parameters and determine the validation characteristics for the analysis of residual content of avermectins in milk. The UHPLC-MS/MS method has proved to be accurate, practical and universal. This was confirmed by Decision limit (CCα) data: abamectin - 12.56 μg/kg, doramectin - 17.74 μg/kg, eprinomectin - 24.02 μg/kg, ivermectin - 12.53 μg/kg, moxidectin - 44.69 μg/kg, recovery is 88.7-110%. The data obtained for assessing the suitability, accuracy and reproducibility of the results meet the requirements of the European Directive (2002/657/EC). The efficient ultra high-performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) method that was developed and adopted for routine use by the laboratories of veterinary medicine, allows to detect residual quantities of 5 avermectins used in animal breeding for the prevention of helminthiases in food products including milk.

Background This study aimed to quantify and compare serum aldosterone (sALD) levels through three different chemiluminescence immunoassays (CLIAs) and liquid chromatography tandem mass spectrometry (LC-MS/MS) analysis. Methods Serum samples from 221 patients with suspected primary aldosteronism (PA) were retrospectively included in this study conducted at the Peking Union Medical College Hospital from June to August in 2017. sALD levels were determined using the LC-MS/MS method and three different CLIA systems, viz., DiaSorin® XL, iSYS and Auto Lumo A2000. Pooled fresh serum samples were used for recalibration. Passing-Bablok regression analysis, correlation matrix, and Bland-Altman plots were used to evaluate the concurrence among ALD levels determined using the three CLIAs. Results Within-laboratory precision of the four assays ranged from 2.1% to 9.4%, except the coefficient variation (CV) of one of the CLIAs, which exceeded 20.0% for samples with low sALD levels. sALD levels determined using LC-MS/MS were significantly lower than those determined using the other three CLIAs (p < 0.0001). Spearman's correlation coefficient of the four assays ranged from 0.745 to 0.950 (p < 0.0001). The Bland-Altman plot showed that the average bias (%) for the three CLIAs and LC-MS/MS ranged from -69.3 to -49.2. After recalibration, this correlation did not improve among the assays. However, the bias and bias percentage at the medical decision level improved between LC-MS/MS and DiaSorin® XL/iSYS. Conclusions Significant inconsistencies between the results of CLIAs and LC-MS/MS indicate that different sALD measures cannot be used interchangeably.

Objective A highly feasible and reliable ultra-high performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS)method was presented for therapeutic drug monitoring of five anti-schizophrenic drugs (aripiprazole, amisulpride, olanzapine, paliperidone and ziprasidone) simultaneously and the reference range of plasma concentration was investigated. Methods establishment and evaluation. The selectivity, accuracy, precision, stability and linear range of established UPLC-MS/MS method were evaluated according to FDA and CLSI. After a ten-month clinical application, a retrospective analysis of 253 positive samples was carried out to investigate conformance of the AGNP therapeutic reference range for Chinese patients. Results The five anti-schizophrenic drugs could be simultaneously measured by the established UPLC-MS/MS within 6 minutes. The LOQs were 0.1 to 9.0 ng/ml. The correlation coefficients were all higher than 0.997 7. The intra-day and inter-day precisions were less than 11.1%, and the recoveries ranged from 86.2% to 104.8%. The clinical results suggested the good consistency in reference range with AGNP for olanzapine, aripiprazole, paliperidone and ziprasidone. While for amisulpride, the plasma concentration level (445.2±231.5) ng/ml was significantly higher than the AGNP-recommended range (100-320) ng/ml. Conclusion The established UPLC-MS/MS method was very suitable for monitoring anti-schizophrenic drugs.(Chin J Lab Med, 2017, 40: 787-792) Key words: Antipsychotic agents; Plasmaconcentration; Drug monitoring; Chromatography, high pressure liquid; Tandem mass spectrometry; Reference values

Prevalence and determinants of lower urinary tract symptoms in pregnant women.

Objective To analyze the vitamin D status among apparently healthy younger and elder adults in Beijing based on liquid chromatography tandem mass spectrometry. Methods This is an observational study. Participants included 287 apparently healthy young adults(143 males and 144 females) with an average of (32.2±6.9) years old(19-44 years). At the same time 198 middle- and elder-aged adults were recruited [90 males, 108 females, (55.6±7.6) years], and fasting blood samples were collected and serum were isolated. They measured 25-hydroxyvitamin D (25OHD: 25OHD2 and 25OHD3) using liquid chromatography tandem mass spectrometry method. Vitamin D with deficiency, insufficiency, sufficiency and intoxication was categorized as 25OHD <20 ng/ml, 20-30 ng/ml, 30-150 ng/ml, and ≥150 ng/ml, respectively. ALT, Ca, P, Cr, Glu, TG, TC and iPTH wereanalyzed using automatic analyzers.Statistical analysis was performed using SPSS17.0. Results The median 25OHD level in the total studied younger adults was 16.0[2.5%-97.5%: (6.1-29.0) ng/ml] which didn′t show significant difference with that of middle- and elder-aged adults. Younger males had significant higher level of 25OHD than females [17.9(8.3-32.3) ng/ml vs. 14.4(5.4-26.4) ng/ml, Z= -4.238, P<0.01]. Of the total younger subjects, the rate of vitamin D with deficiency (<20 ng/ml), insufficiency (20-30 ng/ml) and sufficiency (≥30 ng/ml) was 72.8%, 25.1%, 2.1%, respectively, while that of middle- and elder-aged adults was 76.3%, 21.2%, 2.5% respectively, and that of younger males was 65.0%, 30.8%, 4.2%, respectively while that of younger females was 80.6%, 19.4%, 0%, respectively. Younger females had significantly higher rate of 25OHD deficiency (χ2=31.766, P<0.01). With adjusting sex, age and BMI, serum iPTH (r= -0.264, P<0.01) was significantly negatively correlated with 25OHD while Cr (r=0.221, P<0.01) showed significantly positively correlation with 25OHD. Conclusion Vitamin D deficiency is prevalent in both younger and elder adults in Beijing, especially in younger females. (Chin J Lab Med, 2017, 40: 689-692) Key words: Vitamin D; Nutritional status; Tandem mass spectrometry; Chromatography, liquid; Young adult; Aged

Total plasma homocysteine has emerged as an independent risk factor for vascular disease. To meet increasing requests by clinicians for this homocysteine determination, a rapid assay for a routine use has been developed. A robust, stable, isotope-dilution liquid chromatography tandem mass spectrometry (LC/MS/MS) method is described, including all the practical details and analytical performance results. The method allows homocysteine quantitation over a linear working range up to 100 micromol/L, with the limit of quantification estimated at a low value of 0.09 micromol/L. Total analytical imprecision is less than 4%. Accuracy was assessed by measuring the homocysteine concentration in a serum Standard Reference Material. The method was demonstrated to be quick, reliable and cheap after 1 year of use on a time-shared instrument in our hospital unit.

Objectives Hydroxychloroquine (HCQ) is an anti-malarial and immunomodulatory drug reported to inhibit the Corona virus, SARS-CoV-2, in vitro. At present there is insufficient evidence from clinical trials to determine the safety and efficacy of HCQ as a treatment for COVID-19. However, since the World Health Organisation declared COVID-19 a pandemic in March 2020, the US Food and Drug Administration issued an Emergency Use Authorisation to allow HCQ and Chloroquine (CQ) to be distributed and used for certain hospitalised patients with COVID-19 and numerous clinical trials are underway around the world, including the UK based RECOVERY trial, with over 1000 volunteers. The validation of a liquid chromatography tandem mass spectrometry (LC-MS/MS) method for the simultaneous determination of HCQ and two of its major metabolites, desethylchloroquine (DCQ) and di-desethylchloroquine (DDCQ), in whole blood is described. Methods Blood samples were deproteinised using acetonitrile. HCQ, DCQ and DDCQ were chromatographically separated on a biphenyl column with gradient elution, at a flow rate of 500μL/min. The analysis time was 8min. Results For each analyte linear calibration curves were obtained over the concentration range 50-2000μg/L, the lower limit of quantification (LLOQ) was 13μg/L, the inter-assay relative standard deviation (RSD) was <10% at 25, 800 and 1750μg/L and mean recoveries were 80, 81, 78 and 62% for HCQ, d4-HCQ, DCQ and DDCQ, respectively. Conclusion This method has acceptable analytical performance and is applicable to the therapeutic monitoring of HCQ, evaluating the pharmacokinetics of HCQ in COVID-19 patients and supporting clinical trials.

Development and validation of a liquid chromatography tandem mass spectrometry method for the determination of 10 mycotoxins in beer of the Chinese market and exposure estimate

Automating DUID methods using robotics for rapid high throughput sample preparation – Analysis of Delta-9-Tetrahydrocannabinol and its major metabolite Delta-9-tetrahydrocannabinol acid in whole blood

A liquid chromatography tandem mass spectrometry (LC/MS/MS) method has been developed for the fast routine analysis of selected CYP450 probe substrate metabolites in microsomal incubations, with no sample pretreatment. This has allowed fast and simple assessment of the potential effects which drug candidates may or may not have on the metabolism of specific CYP450 probe substrates, providing information which can then be used to rationalize in vivo interaction studies required in the clinic. This methodology takes advantage of fast gradient chromatography as a generic means of sample separation and analysis. It provides high throughput analysis compared to conventional gradient HPLC, with no significant loss in chromatographic performance.

A new, rapid, sensitive, and comprehensive ultra‐high‐performance liquid chromatography tandem mass spectrometry (UHPLC–MS/MS) method for quantifying diuretics (acetazolamide, brinzolamide, dorzolamide, and their metabolites) in human urine and hair was developed and fully validated. Twenty‐five milligrams of hair were incubated with 500‐μl M3® buffer reagent at 100°C for 1 h for complete digestion. After cooling, 1‐μl supernatant was injected onto chromatography system. Urine samples were simply diluted before injection. The chromatographic run time was short (8 min) through a column with a mobile phase gradient. The method was linear (determination coefficients always higher than 0.99) from limit of quantification (LOQ) to 500 ng/ml in urine and from LOQ to 10 ng/mg in hair. LOQs ranged from 0.07 to 1.16 ng/ml in urine and from 0.02 to 0.15 ng/mg in hair. No significant ion suppression due to matrix effect was observed, and process efficiency was always higher than 80%. Intra‐ and inter‐assay precision was lower than 15%. The suitability of the methods was tested with six urine and hair specimens from patients treated with acetazolamide, dorzolamide, or brinzolamide for ocular diseases or systemic hypertension. Average urine concentrations were 266.32 ng/ml for dorzolamide and 47.61 ng/ml for N‐deethyl‐dorzolamide (n = 3), 109.27 ng/ml for brinzolamide and 1.02 ng/ml for O‐desmethyl‐brinzolamide (n = 2), and finally, 12.63 ng/ml for acetazolamide. Average hair concentrations were 5.94 ng/mg for dorzolamide and 0.048 ng/mg for N‐deethyl‐dorzolamide (n = 3), 3.26 ng/mg for brinzolamide (n = 2), and 2.3 ng/mg for acetazolamide (n = 1). The developed method was simple and fast both in the extraction procedures making it eligible in high‐throughput analysis for clinical forensic and doping purposes.

Development and validation of a sensitive ultra performance liquid chromatography tandem mass spectrometry method for the analysis of fentanyl and its major metabolite norfentanyl in urine and whole blood in forensic context

Validation and comparison of a rapid liquid chromatography tandem mass spectrometry method for serum 25OHD with the efficiency of separating 3-epi 25OHD3