颜色 EP 7.0.pdf

2.2.2. Degree of coloration of liquids EUROPEAN PHARMACOPOEIA 7.0 dilute suspensions containing small particles. Linearity between — Resolution : 0.01 NTU within the range of 0-10 NTU, 0.1 NTU turbidity and concentration must be established by constructing within the range of 10-100 NTU, and 1 NTU for the range a calibration curve using at least 4 concentrations. 100 NTU. The instrument is calibrated and controlled with reference standards of formazin. RATIO TURBIDIMETRY In ratio turbidimetry the relationship of the transmission — Accuracy : 0-10 NTU: ± (2 per cent of reading + 0.01) NTU. measurement to the 90° scattered light measurement is 10-1000 NTU: ± 5 per cent. determined. This procedure compensates for the light that — Repeatability : 0-10 NTU: ± 0.01 NTU. 10-1000 NTU: ± 2 per is diminished by the colour of the sample. The influence of cent of the measured value. the colour of the sample may also be eliminated by using — Calibration : with 4 reference suspensions of formazin in the an infrared light-emitting diode (IR LED) at 860 nm as the range of interest. Reference suspensions described in this light source of the instrument. The instrument’s photodiode chapter or suitable reference standards calibrated against detectors receive and measure scattered light at a 90° angle the primary reference suspensions may be used. from the sample as well as measuring the forward scatter (light — Stray light : this is a significant source of error in low level reflected) in front of the sample along