BS ISO 15033:2018 pdf free
BS ISO 15033:2018 pdf free.Plastics一Determination of caprolactam and its cyclic and linear oligomers by HPLC
To calibrate the column for the caprolactam and its cyclic dimer, prepare a series of at least three calibration solutions with concentrations increasing from 100 mg/1 to 1 500 mg/l by dissolution in formic acid (5.5) for caprolactam (5.6) and the cyclic dimer (5.2).
If possible, adjust the concentrations of the calibration solutions in such way that the concentrations of the substance(s) in the sample solution to be determined (Clause 7) are not in the lowest or highest part of the relevant calibration series.
Pump eluent B (5.17) through the column at a rate of 0,81 ml/min. Starting with the lowest concentration of a calibration series, inject 2 ul of the calibration solution into the column in accordance with the injector programme given in Annex B. Elute in accordance with the gradient timetable in Annex B.
Record the UV chromatogram. Measure the peak area of the components.
Repeat the calibration successively for the other calibration solutions of the same component and for the other calibration series.
NOTE Calibration can also be carried out using a commercially available PA6 polymer with a known concentration of cyclic oligomers (see Reference [3]).
Introduce a test sample (see Clause 7) into a 25 ml volumetric flask. Add 20 ml of formic acid (5.5),close the flask and dissolve the sample, optionally by using ultrasonic vibration. Make up to the mark with formic acid (5.5). Pump eluent A (5.17) through the column at a flow rate of 0,51 ml/min.Inject 2 μl the sample solution into the column in accordance with the injector programme given in Annex A. Elute in accordance with the gradient timetable in Annex A. Record the UV chromatogram (see Figure 1). If applicable, immediately after UV detection, add the post-column reagent (5.23) at a flow rate of 0,25 ml/min, mixing the eluent and the reagent in the reaction coil. Record the fluorescence chromatogram (see Figure 2). Measure the peak areas of the cyclic oligomers (UV detection) and linear oligomers (fluorescence detection) up to and including the hexamer.
If necessary, e.g. if lower sensitivity is necessary due to high(er) concentrations, caprolactam can be detected by UV absorption at 220 nm instead of 200 nm.
NOTE The cyclic dimer of caprolactam elutes before caprolactam. See References [1], [2] and [3].BS ISO 15033 pdf download.
