ABSTRACT
A simple and rapid HPLC-MS/MS analytical method was developed and validated for the determination of methylmalonic acid (MMA) in human serum without a derivatization step. Serum samples (200 µl) were pretreated using a simple method based on ultrafiltration using a VIVASPIN 500 ultrafiltration column. Chromatographic separation was achieved on a Luna Omega C18 column with a PS C18 precolumn guard by gradient elution using 0.1% (v/v) formic acid in water (mobile phase A) and 0.5% (v/v) formic acid in acetonitrile (mobile phase B) at a flow rate of 0.2 ml min-1 . The total run time of the analysis was 4.5 min. Negative electrospray ionization and multiple reaction monitoring mode were used. The lower limit of detection and lower limit of quantification for MMA were determined to be 13.6 and 42.3 nmol L-1 , respectively. The developed method enabled the quantification of MMA in a wide linear range of 42.3-4230 nmol L-1 with a correlation coefficient of 0.9991.
Subject(s)
Methylmalonic Acid , Tandem Mass Spectrometry , Humans , Chromatography, High Pressure Liquid/methods , Tandem Mass Spectrometry/methods , Formates , Reproducibility of ResultsABSTRACT
A novel method for determination of platinum species by application of graphite furnace atomic absorption spectrometry (GFAAS) was developed. The principle of determination is the formation of platinum ion associates (IA) with SCN- and polymethine basic agent 1,3,3-trimethyl-2-[3-(1,3,3-trimethyl-1,3-dihydroindol-2-yliden)-propyl-1,3-dienyl]-3H-indolium chloride (TTDI), which can then be extracted by various organic solvents. Different options for analytical signal intensification (ultrasonic and microwave energy) were examined. The conditions found for ion associate formation and extraction have enabled the proposing of a new Pt(II) and Pt(IV) speciation process. These species can be reliably determined simultaneously at concentration ratios from 1:5 to 5:1. Moreover, the ion associates of platinum with TTDI can be extracted with toluene up to a volume ratio of aqueous and organic phases of Vaq:Vorg = 50:1. This fact for Pt determination using GFAAS means decreasing the limit of detection (LOD) from 7.1µgL-1 to 0.3µgL-1. The method was applied for Pt determination in a model and in spiked water samples.
ABSTRACT
The aim of this study was to investigate total mercury (THg) and methylmercury (MeHg) exposure of 75 mother-child pairs in relation to their thyroid hormone status (thyroid-stimulating hormone (TSH), triiodothyronine (T3), free triiodothyronine (fT3), thyroxine (T4), and free thyroxine (fT4)). THg and MeHg in blood samples were measured by atomic absorption spectrometry and gas chromatography-inductively coupled plasma-mass spectrometry, respectively. The median THg and MeHg levels in maternal blood, cord blood, and blood of 6-month-old children were 0.50, 0.53, and 0.32 and 0.22, 0.32, and 0.08 µg/L, respectively. There were significant correlations between paired maternal-cord blood levels for THg and MeHg, with a greater transplacental transport of MeHg compared with THg (mean cord/maternal blood ratio, 1.80 vs. 1.24). The maternal blood THg was found to be a better predictor of TSH levels in children than their current THg exposure. There was a positive correlation between maternal THg and children's TSH. T3 and fT3 levels in children were negatively related to cord blood THg in the majority (Caucasian) subgroup, whereas these associations were positive in the Roma subgroup. Mothers with dental amalgam fillings had significantly lower T4 and fT4 levels. Moreover, fT4 in the mothers of boys negatively correlated with maternal THg levels. MeHg exposure lowered T3 levels in the mothers of girls. Our results suggest that low-level exposure to Hg can affect thyroid hormone status during prenatal and early postnatal exposure depending on the form of Hg, gender, ethnicity, lifestyle, or socioeconomic status (dental amalgam fillings).
