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yzhlasiI

铁虫 (正式写手)

[求助] 气相色谱检测方法问题,请教大家!!

这个方法是做顶空的吗?
各位老师,帮帮忙,小弟是新手。

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,?=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).  


这个方法是不是顶空方法,如果是的话,里面怎么没有顶空条件?难道是硅烷化反应的条件就包含了顶空条件(Seal the vial and heat at 70 ± 5 °C for 20 min.)还是说顶空条件要自己摸索?
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apm19861204

金虫 (小有名气)

【答案】应助回帖


感谢参与,应助指数 +1
西湖醉鱼(金币+1): 欢迎来分析版指导 2012-02-09 17:33:01
你这个不是顶空  是硅烷化的预处理哎  你是不是还发了一个帖子问单糖的GC分析  这个就是单糖的预处理方法之一   我以前做的用的是甲酰化  那个问道比较重  你这个方法我没有用过  但是很类似  也需要密封后在烘箱中加热反应后  进样的
4楼2012-02-09 17:01:38
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nanjingzyf

铁虫 (初入文坛)

【答案】应助回帖


感谢参与,应助指数 +1
408851978(金币+1): 新人奖,鼓励应助 2012-02-09 10:48:23
直接进样1ul 看进样量就可以了呀
2楼2012-02-09 09:19:12
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yzhlasiI

铁虫 (正式写手)

引用回帖:
2楼: Originally posted by nanjingzyf at 2012-02-09 09:19:12:
直接进样1ul 看进样量就可以了呀

如果是直接进样,那样品处理这样合理吗?用5ml二氯甲烷萃取2次后,于10ml螺丝帽玻璃容瓶中蒸干萃取物中残留的二氯甲烷,加入0.5ml硅烷化溶液。密封玻璃瓶放置于70±5。C的烘箱中加热20min.这样处理后再转移到1.5ml小玻璃瓶中进样分析,这么小的体积好转移吗?不转移的话,能直接进样吗,10ml的瓶子0.5ml左右的体积?
3楼2012-02-09 13:27:31
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