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气相检测方法问题，请教大家！！

kzhchg2006

2012/02/08

气相色谱（GC）

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？

相关话题

symmacros

第1楼2012/02/08

应助达人

参考：http://bbs.instrument.com.cn/shtml/20120207/3850053/

0

kzhchg2006

第2楼2012/02/09

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？

0

symmacros

第3楼2012/02/09

应助达人

需要转移到1.5ml小玻璃瓶中进样分析，可能是用自动进样器进样，但方法没提到是否定容。是不是手动进样就可以直接进样，不用转移？
kzhchg2006(kzhchg2006) 发表: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？

0

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