ABSTRACT
Acid extraction is commonly used to analyze arsenic species in rice. During the extraction process, spiked monomethylarsonic acid (MMA) is often transformed into different compounds. A similar phenomenon is observed in the arsenic speciation analysis of seafood. To identify these compounds, we analyzed a previously prepared extract using liquid chromatography-time-of-flight/mass spectrometry in differential analysis and liquid chromatography-inductively coupled plasma-MS. The compound was identified as monomethylmonothioarsonic acid (MMMTA), a thioarsenical, which is estimated to be more cytotoxic than MMA. As MMMTA was readily produced by bubbling hydrogen sulfide through MMA, this suggests that MMA reacts with sulfur in rice during the extraction process. Our data also suggested that dimethylarsinic acid could be transformed into another compound, although the generation rate was low. For reliable arsenic speciation analyses, the transformation of arsenic compounds during extraction must be avoided. This study demonstrates that arsenic compounds can be transformed by dilute acid extraction.
Subject(s)
Arsenic , Arsenicals , Arsenic/analysis , Arsenic/chemistry , Chromatography, High Pressure Liquid/methods , Arsenicals/analysis , Arsenicals/chemistryABSTRACT
Objective: To establish a high performance liquid chromatography-inductively coupled plasma mass spectrometry(HPLC-ICP-MS)method for the determination of trivalent arsenic(AsIII),pentavalent arsenic(As), methyl arsenic(MA),dimethyl arsenic(DMA),arsenical choline(AsC)and arsenical betaine(AsB)in traditional Chi- nese medicine Cordyceps. Methods: The arsenic species in Cordyceps were extracted with hot 0.15 mol/L nitric acid so- lution,separated by HPLC on a Dionex IonPacTM AS7 column(4 mm×250 mm,5 μm)with aqueous 5 mmol/L and 100 mmol/L ammonium carbonate solutions in a gradient elution as mobile phase,and quantitatively determined by ICP-MS. Results: The six kinds of arsenic species showed a good linearity within the range of 5-200 μg/kg. The average recovery was 83.3-115.9%,and the relative standard deviation was less than 5%. The main form of arsenic species in C ordyceps was inorganic arsenic(AsIIIand As),and the total content of ASIII+Asvaried around 1 mg/kg in the three tested batches of samples. Conclusion: The established HPLC-ICP-MS method is convenient,accurate and reliable for the analysis of different arsenic species in Cordyceps. In addition,the present work on the determination of six arsenic species in Cordy- ceps could be used as reference for improvement of the limitation standard of arsenic in Cordyceps.
ABSTRACT
Objective To establish the method of high performance liquid chromatography and hydrid genesis atomic fluorescence spectroscopy(HPLC-HGAFS) about arsenic species in urine of rats treated with sodium arsenite.Methods The solution containing 15 mmol/L(NH4)2HPO4(pH=6.0)was used as the chromatographic eluant,the flow rate of which was 1.0 ml/min.The parameters of HPLC-HGAFS consisted of multiplier negative high voltage,hollow-cathode lamp's joint current and co-current,the flow rate of carrier gas,the flow rate of barrier shield gas,supporting liquid and reducing agent,which were 285 V,80 mA,36 mA,400 ml/min,600 ml/min,7%HCl and the mixed liquor of 1.5%KBH4 and 0.35% KOH respectively.Results The linear range of method was 20-100 ?g/L,and the linearity of regression equation of iAs3+,iAs5+,DMA was better.The lowest detection concentration of iAs3 +,iAs5 +,DMA in urine were 12.03,6.67 and 8.66 ?g/L respectively and all of the coefficient correlation were ≥0.98.The average recovery rates of DMA were 96.5%-103.4% and RSDs were 0.39%-1.26%.Conclusion The method has been proved accurate,sensitive and is applicable to the determination of arsenic species in urine.
