ABSTRACT
A rapid and sensitive method for the determination of trace carbaryl in water by using diallyl phthalate-europium ( Eu3+) as fluorescent probes was developed. The interaction between Eu3+ and diallyl phthalate and carbaryl was studied by high resolution mass spectrum, and the fluorescence spectra change of complexes before/after binding with carbaryl was also investigated. The influence factors of fluorescence intensity including solution pH and interferent were studied. The results showed that two diallyl phthalate molecules were complexed with one Eu3+to form stable complexes. Carbaryl could also interact with the probe to form multiple complexes, which significantly increased the fluorescent efficiency of the probe. At pH 9. 0 of solution and by using 245/615 nm as excitation/emission wavelength, the fluorescence intensity showed good linear relationship with the carbaryl concentration ranged from 6. 25í10-8 mol/L to 2. 50í10-6 mol/L, and the linear correlation coefficient was 0. 9968. The detection limit of the method was 9. 6í10-9 mol/L. Water samples were extracted by acetonitrile, and then detected by europium ( Eu3+)-diallyl phthalate fluorescent probe. The recovery of the method was 91. 8%-94. 5%, while RSD was within 6. 1%. The method is suitable for the rapid determination of carbaryl in 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
A method for the determination of seven kinds of thiocarbamate herbicides, molinate, pebulate, vernolate, triallate, thibencarb, eradicane and butylate in black tea and green tea has been developed. After homogenization, 2.0 g tea sample was soaked with 6 mL water for 1 h. 2.5 g NaCl was then added, and the sample was extracted twice by 20 mL acetonitrile. After concentration, the extract was put through HLB column and eluted by 3 mL acetonitrile. The eluate was then concentrated and dissolved with 2.0 mL hexane-acetone (7∶ 3, V/V) mixture. The preparation was cleaned by Envi-Carb column and eluted with 5 mL hexane-acetone. After concentration, the residue was dissolved by acetonitrile-water (5∶ 5, V/V) solution. Detection was achieved by electrospray ionization(ESI) in positive mode using multiple reaction monitoring. D_3-carbaryl was used as the internal standard, the linear range for the herbicides was 0-200 μg/L and the limit of detection were from 0.093 to 1.77 μg/L, with the correlation coefficients(r) varying from 0.9954 to 0.9988. The recoveries of all thiocarbamate herbicides were from 77.3% to 91.5% at the spiked levels of 5-20 μg/kg. The RSD of each compound was less than 15%. Black tea and green tea samples were successfully analyzed by the proposed method with satisfactory results.