ABSTRACT
A method for rapid determination of semicarbazide in water by hydrophilic interaction chromatography-quadrupole / electrostatic field orbitrap high resolution mass spectrometry was developed. The sample was extracted with acetonitrile after 0. 1 mol/ L NaOH was added in the sample and then excessive amounts of Na2 SO4 was added to stratify acetonitrile from the mix solution. The acetonitrile extraction solution was dehydrated with anhydrous sodium sulfate. The preparation was separated by an amide column using as hydrophilic interaction column, and gradient elution program was employed by using water and acetonitrile containing 0. 1% formic acid as mobile phase, then it was detected in positive and selected ion monitoring mode by a quadrupole / electrostatic field orbitrap high resolution mass spectrometry. Internal standard method was used for quantitative analysis. The linear correlation coefficient of semicarbazide was 0. 997 in the concentration range of 0. 2 -20 μg / L under the optimal conditions. The limit of detection was 0. 09 μg / L, while the limit of quantitation was 0. 30 μg / L. The recoveries were 82. 3% to 92. 0% , and the relatively standard deviations were less than 7. 6% at the spiked levels of 0. 5, 1. 0 and 5. 0 μg / L using river water and sea water as blank samples. The developed method is suitable for the analysis of trace semicarbazide in environment water samples.
ABSTRACT
A method was developed for the determination of eight steroid hormones ( estrone, α/β-estradiol, estriol, testosterone, epitestosterone, progesterone and testosterone propionate ) in butter samples by gel permeation chromatography ( GPC) purification-followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The samples were first extracted by ethylacetate/cyclohexane (1:1, V/V) and the extract was later degreased by GPC column. Then, the GPC concentrate was separated using a C18 column ( 100 mm í2. 0 mm i. d. , 3. 0 μm) with gradient elution of acetonitrile/water. Finally, the steroid hormone components were qualitatively and quantitatively determined by mass spectrometer with electrospray ionization in multi reaction monitoring mode. Using matrix matched external standard method, good linearity in response could be obtained in the concentration range of 1 . 0-20 . 0 μg/kg with correlation co-efficiency larger than 0 . 999 . The detection limits of the method were 0. 04-0. 30 μg/kg and the quantification limit was 1. 0 μg/kg. At the spike levels of 1. 0, 2. 0 and 4. 0μg/kg, the recoveries of hormones were within the range of 64. 1%-110%, and the relative standard deviation ( RSD) was less than 11%. The results show that the method is accurate and reliable, and meets the requirements for determination of 8 steroid hormones in butter samples.
ABSTRACT
Mammal metallothionein(MT) folds into two separate domains that exhibit different structure and metal binding propertity independently, the study of the strategy of metal ions binding with MT would give better understanding of their exact biological functional mechanisms. In this study, a method using eletrospray ionization mass spectrometry (ESI-MS) phase liquid chromatography and identified by ESI-MS. Different amounts of Cd or Cu were then added in MT-2a samples and ESI-MS was employed to determine the mass difference of MT in different samples. The results Cd2+4S11; while Cd is attached in separate binding sites for the formation of Cd2+3S9 cluster, which intermediately formed with five and six Cd ions were detected. For the Cuprous ions, it prefers to cooperatively bind in β-domain with the form of Cu4-MTβ. The binding form in β-domain would convert from Cu4 into more Cu binding form with the addition of Cu. When high concentration of Cu was added in samples, the result suggested that