1.1 This test method covers a procedure for evaluating the limits of the linearity of response with fluorescence intensity of fluorescence-measuring systems under operating conditions. Particular attention is given to slit widths, filters, and sample containers. This test method can be used to test the overall linearity under a wide variety of instrumental and sampling conditions. The results obtained apply only to the tested combination of slit width and filters, and the size, type and illumination of the sample cuvette, all of which must be stated in the report. The sources of nonlinearity may be the measuring electronics, excessive absorption of either the exciting or emitted radiation, or both, and the sample handling technique, particularly at low concentrations.

1.2 This test method has been applied to fluorescence-measuring systems utilizing continuous and low-energy excitation sources (for example, an excitation source of 450-W electrical input or less). There is no assurance that extremely intense illumination will not cause photodecomposition of the compounds suggested in this test method.² For this reason it is recommended that this test method not be indiscriminately employed with high-intensity light sources. It is not a test method to determine the linearity of response of other materials. If this test method is extended to employ other chemical substances, the principles within can be applied, but new material parameters, such as the concentration range of linearity, must be established. The user should be aware of the possibility that these other substances may undergo decomposition, or adsorption onto containers.

1.3 This test method has been applied to fluorescence-measuring systems utilizing a single detector, that is, a photomultiplier tube or a single photodiode. It has not been demonstrated if this method is effective for photo-array instruments such as those using a CCD or a diode array detector.

1.4 This test method is applicable to 10-mm pathlength cuvette formats and instruments covering a wavelength range within 190 to 900 nm. The use of other sample formats has not been established with this test method.

1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.