Tetracycline, oxytetracycline and chlortetracycline determination by flow injection potentiometry

This paper describes tetracycline (TCH), oxytetracycline (OTCH) and chlortetracycline (CTCH) determination by flow injection potentiometry. In the flow system proposed TC samples are inserted in a carrier solution and converged with a Cu(II) solution of known concentration; the Cu(II) decrease due to its complexation with tetracyclines (TC) was monitored. The detector used was a homogeneous crystalline CuS/Ag2S double membrane tubular electrode with increased sensitivity. The present system allows tetracyclines determinations within a 48.1-4.8 x 10(3) ppm for TCH, 49.1-4.9 x 10(3) ppm for OTCH and 51.5-5.1 x 10(3) ppm for CTCH and a precision better than 0.4% for the three TC species. This procedure accomplishes 150-200 samples h(-1) with a Cu(II) consumption of about 13 microg determination(-1).