Capillary column gas chromatography--mass spectrometry in studies on rheumatoid arthritis.

A method is described for determining the organic acid profile of synovial fluid. The method requires 50--100 microgram of sample and involves ion exchange for isolation of the acids followed by combined capillary column gas chromatography--mass spectrometry. Normal synovial fluid and synovial fluid from patients with rheumatoid arthritis show a similar qualitative pattern of acids (mainly fatty acids) resembling the pattern found in serum. The concentrations of the organic acids in the abnormal synovial fluids are 5--10 times higher than those in the fluid from the normal joints. In patients receiving treatment with gold thiomalate, free thiomalate was excreted in the urine. The release of this thiol upon gold therapy is of consequence for the further understanding of the mechanism of action of certain drugs against rheumatoid arthritis.