1. Instruments
Gas chromatograph: with FID detector
chromatographic column: 30m×ø0.25mm(id), SE-30 capillary column with film thickness of 0.5µM
Microinjector: 10µL
Chromatographic data processor
2. Operating conditions of gas chromatography
Column temperature: 220℃; Vaporization room: 260℃; Detector room: 260℃.
Split injection: split ratio 1:50
Injection volume: 0.4 μL
Retention time: 15-Crown-5 about 6min
The above chromatographic conditions are typical operating parameters. The operating parameters can be adjusted appropriately according to the operating characteristics of different instruments in order to obtain the best effect.A typical gas chromatogram is shown in Figure 1
Figure1 gas chromatogram of 15-crown-5
3. Determination steps
3.1 Under the above operating conditions, after the instrument baseline is stable, inject several needles of sample repeatedly, and calculate the content when the change of relative response value of two adjacent needles is less than 0.5%.
3.2 calculation
Assay of 15-Crown-5 Xi (%), calculate as formula:
Xi%=
Ai×100%
∑Ai
In formula:
Xi: Percentage content of 15-Crown-5;
Ai: Peak area of 15-crown-5;
∑Ai: Sum of chromatographic peak areas in sample solution.
3.3 Allowable difference
The difference between the two parallel determinations results should not exceed 0.50%, taking the arithmetic mean as the determination result.
