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南方科技大学公共卫生及应急管理学院2025级博士研究生招生报考通知

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yzhlasiI

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[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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1楼2012-02-08 15:23:21

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nanjingzyf

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专业: 色谱分析

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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

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2楼2012-02-09 09:19:12

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yzhlasiI

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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？

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3楼2012-02-09 13:27:31

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