Arsenic Content,Species and Crystal Construct Analysis of Realgar and Prescriptions Containing Realgar

Objective To determine arsenic contents and species in Realgar and prescriptions containing Realgar,and analyze crystal construct of Realgar. Methods Total arsenic in medicines was determined by fluorescence spectrometry(AFS) with microwave digestion.Soluble arsenic was determined by AFS after artificial gastric juice extract treatment.Two soluble inorganic arsenic species(AsⅢ and AsⅤ) were separated by ion-exchange resin and tested by AFS.Crystal construct of Realgar was tested by X-ray diffraction,and element composition was tested by X-fluorescence spectrometry.Results The amount of arsenic sulfide in Realgar was 97.3%.The experiments indicated that Realgar was a mixture of β-Realgar(As4S4)and α-Realgar(AsS),also containing a little As2S2 and As2S3.The mole ratio of arsenic and sulphur(As/S) was 1.00001.Other elements(Al,Si,K,Ca,Ti,Fe,Sb,Ni,Cu and W) amounted 1.99%.Soluble arsenic could be detected in the artificial gastric juice extract of Realgar and prescriptions.The contents of soluble arsenic,AsⅢ and AsⅤ varied with different sources of Realgar.The amount of soluble arsenic in Realgar was 0.62%,including 0.42% AsⅢ and 0.18% AsⅤ respectively. Conclusion Two soluble inorganic arsenic species(AsⅢ and AsⅤ) exit in Realgar and prescriptions containing Realgar.It is necessary to improve quality control of Realgar.