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Variations in quality of carbol fuchsin stains collected from routine tuberculosis laboratories
1National Reference Laboratory, Beijing Chest Disease and Tumour Hospital, Beijing, China.
Setting:
In-use carbol fuchsin stains were collected from 10 different routine acid-fast bacilli smear microscopy laboratories.
Objective:
To examine the variations in the composition of carbol fuchsin stains.
Method:
Carbol fuchsin concentrations were first determined spectrophotometrically by measuring absorbance at 547 nm. High-performance liquid chromatography (HPLC) separated and quantified the four basic fuchsin homologues: para-rosaniline, rosaniline, magenta II and new fuchsin, and identity was confirmed by mass spectrometry (MS).
Results:
Absorbance measurement showed that three of 10 (30%) samples contained insufficient carbol fuchsin (<70%). Wide variations in relative proportions of fuchsin homologues were found.
Conclusion:
The relative abundance of rosaniline + new fuchsin was quite stable among the different laboratories. Spectrophotometry and HPLC/MS are necessary and sensitive tools for monitoring fuchsin quality.
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