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[求助] GC样品分析问题，谢谢大家了。。

药典方法求助
各位老师，帮帮忙。以下是药典方法：
Silylation solution. To 2 mL of N,O-bis(trimethylsilyl)tri-
fluoroacetamide R add 0.04 mL of chlorotrimethylsilane R
and mix.
Test solution.Dissolve50.0mgofthesubstancetobeexamined
in 3 mL of water R and add 0.5 mL of hydrochloric acid R.
Extract with 2 quantities, each of 5 mL, of methylenechlorideR.
Evaporate the combined methylene chloride extracts to dryness
in a vial with a screw cap and add 0.5 mL of the silylation
solution.Sealthevialandheatat70±5°Cfor20min.

其中，Seal the vial and heat at 70±5°C for 20min.这个是单单指硅烷化反应的温度和时间吗？有没有包括后面顶空平衡的温度和时间？还是说后面顶空平衡的温度和时间需要自己摸索设定?

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1楼2012-02-07 11:48:08

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引用回帖:

2楼: Originally posted by ltxin2009 at 2012-02-07 12:00:46:
不够完整，最好把后面的具体操作过程也写出来。

这是整个气相方法：
TESTS
pH (2.2.3): 6.5 to 7.5.
Dissolve 0.20 g in carbon dioxide-free water R and dilute to
10 mL with the same solvent.
Impurity C. Gas chromatography (2.2.28).
Silylation solution. To 2 mL of N,O-bis(trimethylsilyl)tri-
fluoroacetamide R add 0.04 mL of chlorotrimethylsilane R
and mix.
Test solution.Dissolve50.0mgofthesubstancetobeexamined
in 3 mL of water R and add 0.5 mL of hydrochloric acid R.
Extract with 2 quantities, each of 5 mL, of methylenechlorideR.
Evaporate the combined methylene chloride extracts to dryness
in a vial with a screw cap and add 0.5 mL of the silylation
solution.Sealthevialandheatat70±5°Cfor20min.
Reference solution (a).Dissolve5.0mgof sodium
phenylbutyrate impurity C CRS in methylenechlorideR and
dilute to 10.0 mL with the same solvent.
Reference solution (b). Dilute 1.0 mL of reference solution (a)
to 10.0 mL with methylenechlorideR.Place1.0mLofthis
solution in a vial with a screw cap, evaporate to dryness and
add 0.5 mL of the silylation solution. Seal the vial and heat at
70±5°Cfor20min.
Reference solution (c). Dissolve 10 mg of the substance to be
examined in 25 mL of water R. To 3 mL of this solution add
0.1 mL of hydrochloric acid R. Extract with 2 quantities, each
of 5 mL, of methylene chloride R. Combine the methylene
chloride extracts in a vial with a screw cap and add 2 mL of
reference solution (a). Evaporate to dryness and add 0.5 mL of
the silylation solution. Seal the vial and heat at 70 ± 5 °C for
20 min.
Column:
— material :fusedsilica;
— size: l =25m,Ø=0.25mm;
— stationary phase: poly(dimethyl)(diphenyl)siloxane R (film
thickness 1.0 μm).
Carrier gas : helium for chromatography R.
Flow rate:0.9mL/min.
Split ratio: 1:100.
Temperature:
                        Time(min) Temperature(°C)
Column             0-5                50
                        5 - 27          50 → 270
                        27 – 32    270
Injection port                      270
Detector                               270
Detection:flameionisation.
Injection:1 μL.
Relative retention with reference to phenylbutyrate (retention
time = about 20 min) : impurity C = about 0.98.
System suitability: reference solution (c) :
— resolution: minimum 3.0 between the peaks due to
impurity C and phenylbutyrate.
Limit :
— impurity C:notmorethantheareaofthecorresponding
peak in the chromatogram obtained with reference
solution (b) (0.1 per cent).
Related substances. Liquid chromatography (2.2.29).