x*******i
发帖数: 623 | 1 我在文献上能找到苯的quadrupole，但是甲苯和乙苯的找不到。有一篇paper说甲苯和
乙苯这种带有极性的分子式没法测quadrupole的。但是如果用计算能得到他们的
quadrupole也行~哪位大侠帮帮我~可惜了我大学化学学得跟一坨便便一样~ |
|
F****I
发帖数: 270 | 2 带极性的分子可以测quadrupole moment，比如氟化氢
J. Mol. Spectrosc., 1973, 48, 427
我不知道甲苯和乙苯有谁测过
计算值可以在
http://cccbdb.nist.gov/quadrupole1.asp
输入分子式找到
不过quadrupole moment不同作者有不同定义，而且对于偶极距不等于零的分子，四级
矩和坐标有关系。（一般的说，第一个非零的多级矩和坐标原点无关，高阶的有关，
Jackson电动的一个习题-.-）实验值一般是用质心系，计算值取决于作者的设置。不知
道nist的具体定义是什么. |
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h********n
发帖数: 4079 | 3 我的意思是, 多数都是MALDI-TOF, 但我看到一个MS是Quadrupole TOF, 这个有啥特点
或者特别的原因要这样设计呢?
专业人士能不能给说说.
谢谢. |
|
b*******g
发帖数: 1309 | 4 I bet what you mentioned is ESI-Q-TOF,
ESI-Q-TOF is similar as ESI-QqQ
TOF used here instead of Q is to improve mass accuracy.
QToF is much cheaper than FT MS, but the mass accuracy is also good (1-5ppm)
, and the scan speed is very fast, so it become more and more popular.
With the MALDI source, there is instrument called MALDI-ion trap-TOF,
produced by Shimadzu. Ion trap is used to select and fragment ions, then you
can do MS/MS or more.
There are also some home-made MALDI-quadrupole-TOF instr... 阅读全帖 |
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b*****r
发帖数: 203 | 5 MALDI-TOF can only do MS, Quadrupole TOF can do MS/MS. |
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m********r
发帖数: 811 | 6 What is the shortest non-zero lenght, L, of a magnetic quadrupole that is
imaging in the horizontal plane, with omega=9 ? |
|
k****o
发帖数: 728 | 7 忘记问了，你precursor isolation用的是quadrupole isolation吧。别用IT
isolation。OF用quadrupole isolation是Thermo建议的，原因这里就不细说了。跟过
去变化很大。 |
|
k****o
发帖数: 728 | 8 确实没必要太push到极致，那些都是厂商吹嘘的。我们仔细研究过quadropole iso和IT
iso的效果，虽然quadrupole能到0.7那么窄，但也会损失isolation efficiency。IT
的isolation效果更差，具体原因不确定（--可能也是为何Thermo那么推荐quadrupole
isolation的原因），毕竟整体ion transmission的结构于过去有了巨变。很多时候要
看你的样品真有那么复杂吗，是否值得用那么窄的window去isolate。 1.6 m/z的iso比
较靠谱。 |
|
|
m********r
发帖数: 811 | 9 【 以下文字转载自 Physics 讨论区 】
发信人: miniplayer (mplayer), 信区: Physics
标 题: What is the shortest non-zero lenght, L, of a magnetic quadrupole that is imaging in the horizonta
发信站: BBS 未名空间站 (Mon Aug 31 18:20:27 2009, 美东)
What is the shortest non-zero lenght, L, of a magnetic quadrupole that is
imaging in the horizontal plane, with omega=9 ? |
|
l*********9
发帖数: 7 | 10 Sr. Scientist Bioanalytical Mass Spectrometry
Currently seeking a bioanalytical expert who specializes in the metabolism
and metabolite identification of peptide drugs using state-of-the-art mass
spectrometry techniques.
Responsibilities:
Provide pre-clinical pharmacokinetic analysis and metabolite
characterization for our proprietary “Stapled Peptide” drug candidates
using state-of-the-art mass spectrometry techniques.
Independent design and execution of bioanalytical methods
Bioanalytical exp... 阅读全帖 |
|
j*********g
发帖数: 3179 | 11 来自主题: JobHunting版 - CS真难学 理科人必修。我觉得国内讲法太注重计算能力。实际上把这些数学和实际应用结合起来
讲，很容易懂。比如，零边界条件的bessel函数其实就是鼓面震动的本征解。国内课本
讲一大堆函数性质。到最后学生全忘光了，遇到要用bessel函数的时候都不知道用。
比如电磁场说到底就是球和谐函数展开加波动方程，什么dipole,quadrupole全搞定。
国内教育太注重知识细节，学生学完不知道自己学的是什么个东西。 |
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b*****s
发帖数: 18 | 12 【 以下文字转载自 Chemistry 讨论区 】
发信人: bigjobs (jobs), 信区: Chemistry
标 题: 内推LC-MS相关职位
发信站: BBS 未名空间站 (Tue Dec 2 00:51:20 2014, 美东)
大家找，想找LC-MS相关职位的同学请看过来，可以帮忙内推。下面是Thermo Fisher公
司的一些职位信息，如果有工业界工作经验最好，没有的话博后经验也可以试试。大家
也可以自己上公司网站看看，如果有别的职位适合你的背景，请发站内信联系，可以内
推。
Product Marketing Specialist, Biopharma Market
in US - California - San Jose, US - New Jersey - Somerset, US -
Massachusetts - Cambridge
Job Description
Position Summary:
The Product Marketing Specialist is expected to be the expert in regards t... 阅读全帖 |
|
g******3
发帖数: 170 | 13 【工作机会】
Reidge Inc. is a well-funded start-up company aiming to develop cutting-edge
technologies and products to improve healthcare outcome and realize
precision medicine. Currently we are seeking a Research Scientist/Senior
Scientist to join our research team. He/She will be responsible for method/
product development to support in vitro diagnostic kit development using
liquid chromatography-mass spectrometry technology. This position will be
based in San Jose, CA.
Duties & Responsibilities
... 阅读全帖 |
|
g******3
发帖数: 170 | 14 【工作机会】
Reidge Inc. is a well-funded start-up company aiming to develop cutting-edge
technologies and products to improve healthcare outcome and realize
precision medicine. Currently we are seeking a Research Scientist/Senior
Scientist to join our research team. He/She will be responsible for method/
product development to support in vitro diagnostic kit development using
liquid chromatography-mass spectrometry technology. This position will be
based in San Jose, CA.
Duties & Responsibilities
... 阅读全帖 |
|
m****s
发帖数: 18160 | 15 【 以下文字转载自 Boston 讨论区 】
发信人: Sciex (LCMSMS), 信区: Boston
标 题: [供求][Job Opening]: Bioanalytical Scientist
发信站: BBS 未名空间站 (Wed Oct 31 11:18:01 2012, 美东)
My group will have an opening position for Bioanalytical Scientist soon.
This is a mid level position, so we don’t need PhD candidate. Meanwhile, we
only look for local candidate at Great Boston area. If you or someone has
interest, please drop me an email at p***[email protected].
Thanks,
Here is the job description:
Description of duties:
The successfu... 阅读全帖 |
|
e******i
发帖数: 341 | 16
in NJU, they ICP-AES, ICP-MS(quadrupole-i guess, i don't think it is MC-ICPMS)
i don't know about laser ablation, what is that for?
for thin sections? |
|
m******i
发帖数: 73 | 17 【 以下文字转载自 Chemistry 讨论区 】
发信人: mutouhui (mutouhui), 信区: Chemistry
标 题: Postdoc postions in LC-mass spectrometry quantitation
发信站: BBS 未名空间站 (Tue Jun 15 11:59:36 2010, 美东)
Two Postdoc positions are available immediately at University of North
Carolina at Chapel Hill. We are working on quantitation of carcinogen-
induced DNA adducts and protein biomarkers. The lab is equipped with 3
Triple quadrupole mass spectrometers, 1 ion trap, 1 ICP-MS and 1 Q-TOF. We
also have several HPLC, UPLC and nano-LC |
|
b*****s
发帖数: 18 | 18 【 以下文字转载自 Chemistry 讨论区 】
发信人: bigjobs (jobs), 信区: Chemistry
标 题: 内推LC-MS相关职位
发信站: BBS 未名空间站 (Tue Dec 2 00:51:20 2014, 美东)
大家找，想找LC-MS相关职位的同学请看过来，可以帮忙内推。下面是Thermo Fisher公
司的一些职位信息，如果有工业界工作经验最好，没有的话博后经验也可以试试。大家
也可以自己上公司网站看看，如果有别的职位适合你的背景，请发站内信联系，可以内
推。
Product Marketing Specialist, Biopharma Market
in US - California - San Jose, US - New Jersey - Somerset, US -
Massachusetts - Cambridge
Job Description
Position Summary:
The Product Marketing Specialist is expected to be the expert in regards t... 阅读全帖 |
|
K******S
发帖数: 10109 | 19 ETD sensitivity/efficiency比CID低是肯定的
CID在ION TRAP里还是最快的
FUSION叫TRIBRID是你可以同时做3件事情.我觉得如何利用这个优势更重要.比如在
ORBITRAP做MS1或者HCD的时候别让ION TRAP闲着.
CID FRAGMENT的时候是M/Z FOCUS的,意味着如果PEPTIDE上的修饰容易掉的话,就不会有
很好的BACKBONE FRAGMENTS (因为修饰掉了M/Z就变了), ETD可以解决这个. 但现在有
HCD了,是QUADRUPOLE FRAGMENTATION (修饰掉了还可以继续FRAGMENTATION),对修饰的
PEPTIDE效果也不错.
尤其FUSION的速度太快了,15HZ ORBITRAP, 20HZ ION TRAP. 那这个当QE使唤有些大材
小用了. |
|
r*****m
发帖数: 3619 | 20 定量还是用 triple quadrupole 做真正的 precursor ion scanning，拿标准品建立
multiple reaction monitoring
Psmart,
Cycle |
|
s*****5
发帖数: 52 | 21 对，是quadrupole isolation，这个也是fusion的优势. window size 1.6 Da,之前去
开会有的组说0.7好，但是我们这仪器完全没效果，不知道咋回事 |
|
w********2
发帖数: 632 | 22 quadruple is passthrough isolation. IT is insitu isolation. IT is dirtier/
noiser.
it seems q-exatvie is better than elite if msn is not needed.
IT
IT
quadrupole |
|
|
p******u
发帖数: 215 | 24 Link: http://dx.doi.org/10.1016/0009-2614(94)00780-2
Title:
Determination of the 23Na nuclear quadrupole moment from molecular data for
NaF and NaCl
Authors:
Pekka Pyykköa and Andrzej J. Sadlejb
Chemical Physics Letters
Volume 227, Issues 1-2, 2 September 1994, Pages 221-228
Please send to w**********[email protected]
Thank you! |
|
p******u
发帖数: 215 | 25 Link:
http://dx.doi.org/10.1016/0009-2614(90)80070-T
Author:
Miroslav Urban and Andrzej J. Sadlej
Title:
The nuclear quadrupole moment of Li: Refined calculations of electric field
gradients in LiH, LiF, and LiCl
Chemical Physics Letters
Volume 173, Issues 2-3, 5 October 1990, Pages 157-163
Please send to
w**********[email protected]
Thank you! |
|
m******i
发帖数: 73 | 26 Two Postdoc positions are available immediately at Department of Environmental Sciences and Engineering, University of North
Carolina at Chapel Hill. We are working on quantitation of carcinogen-
induced DNA adducts and protein biomarkers. The lab is equipped with 3
Triple quadrupole mass spectrometers, 1 ion trap, 1 ICP-MS and 1 Q-TOF. We
also have several HPLC, UPLC and nano-LC systems. The successful candidates
should have hand-on experience on liquid chromatographic techniques and mass
spect |
|
m******k
发帖数: 92 | 27 谢谢建议！我也觉得source应该没有污染，在这个injection后 跑了其他的sample 很
正常，不过用的也是同样的溶剂。因为我用的是triple quadrupole MRM, 设定了要看
我要的化合物，所以没有看到其他的离子。我会把溶剂换掉试试看。也可能是我inject
的MeOH污染了。都换掉都换掉。
而且这两个化合物，carry over还挺严重的，方法可能也要改。。。。 |
|
c******m
发帖数: 884 | 28 小分子(PK)和大分子(peptide, proteins)用的MS/MS主要区别是什么？
QTRAP (Linear Ion Trap + Quadrupole) 可以用来测 peptide 和 protein 吗？
感谢各位大牛，帮帮忙吧。 |
|
L****r
发帖数: 333 | 29 Applied Biosystems 4000 Q TRAP
The 4000 Q TRAP® combines triple quadrupole scan modes with the
advanced features of MDS SCIEX Linear ion trap scans in a single LC/MS/MS
run that identifies, characterizes, and confirms Phase I and II metabolites.
The system includes three sources—an ESI (IonSpray), APCI (Heated
Nebulizer), and NanoSpray—a vacuum pump, and a PC with Analyst 1.4.1
software.
Applied Biosystems 4000
The API 4000 combines a Liquid Chromatography (LC) Mass Spectrometer (MS)
with a... 阅读全帖 |
|
h********n
发帖数: 4079 | 30 Thank you very much.
5ppm)
you |
|
R*******1
发帖数: 6 | 31 Ad Description for BS/MS Sr Associate Scientist
Responsibilities:
• Work within the Analytical Protein Chemistry area to provide
analytical support for novel peptide and protein therapeutics in pre-
clinical and clinical development.
• Primary responsibilities include the identification and
characterization of post-translational modifications in protein therapeutic
candidates, using state of the art separations technology and mass
spectrometry instrumentation, with an emphasis ... 阅读全帖 |
|
x*******i
发帖数: 623 | 32 如果能比较他们的大小也足够了~跪求啊~不然要被老板骂啦~ |
|
x*******i
发帖数: 623 | 33 Thank you so much!!!!!!!!!!请吃包子~ |
|
u**s
发帖数: 384 | 34 Title:Identification of uncommon plant metabolites based on calculation of
elemental compositions using gas chromatography and quadrupole mass
spectrometry.
Journal:Anal Chem. 2000 Aug 1;72(15):3573-80.
Author:Fiehn O, Kopka J, Trethewey RN, Willmitzer L.
Link:http://www.ncbi.nlm.nih.gov/pubmed/10952545 |
|
y*****s
发帖数: 1047 | 35 广告都多得很
Posted/Revised: 5/2/2012
Company/Institute: Pfizer Inc
Department:
Position: 2 Year Postdoctoral Fellow – Protein Quantitation in Tissues
by Mass Spectr
Job Location: Andover, MA United States
Description: 2 year Postdoctoral Fellow – Protein Quantitation in
Tissues by Mass Spectrometry and Immunoanalytical Techniques A Postdoctoral
Fellowship is available in Pfizer’s Pharmacokinetics Dynamics and
Metabolism New Biological Entities (PDM-NBE) in Andover, MA. The PDM ... 阅读全帖 |
|
f********e
发帖数: 2194 | 36 Total 3 papers, all from Bioanalysis.
paper1:
Comparison of triple quadrupole and high-resolution TOF-MS for
quantification of peptides
By Dillen, Lieve; Cools, Willy; Vereyken, Liesbeth; Lorreyne, Willy;
Huybrechts, Tinne; de Vries, Ronald; Ghobarah, Hesham; Cuyckens, Filip
From Bioanalysis (2012), 4(5), 565-579.
http://www.future-science.com/doi/pdf/10.4155/bio.12.3
Paper2:
Comparison of unit resolution SRM and TOF-MS at 12,000 mass resolution for
quantitative bioanalysis of 11 steroids from h... 阅读全帖 |
|
b*****s
发帖数: 18 | 37 大家找，想找LC-MS相关职位的同学请看过来，可以帮忙内推。下面是Thermo Fisher公
司的一些职位信息，如果有工业界工作经验最好，没有的话博后经验也可以试试。大家
也可以自己上公司网站看看，如果有别的职位适合你的背景，请发站内信联系，可以内
推。
Product Marketing Specialist, Biopharma Market
in US - California - San Jose, US - New Jersey - Somerset, US -
Massachusetts - Cambridge
Job Description
Position Summary:
The Product Marketing Specialist is expected to be the expert in regards to
Thermo Fisher Scientific LC-MS products and workflows for the Biopharma
market. Will translate instrument and software perf... 阅读全帖 |
|
|
c******m
发帖数: 884 | 39 小分子(PK)和大分子(peptide, proteins)用的MS/MS主要区别是什么？
QTRAP (Linear Ion Trap + Quadrupole) 可以用来测 peptide 和 protein 吗？
感谢各位大牛，帮帮忙吧。 |
|
R*******1
发帖数: 6 | 40 Ad Description for BS/MS Sr Associate Scientist
Responsibilities:
• Work within the Analytical Protein Chemistry area to provide
analytical support for novel peptide and protein therapeutics in pre-
clinical and clinical development.
• Primary responsibilities include the identification and
characterization of post-translational modifications in protein therapeutic
candidates, using state of the art separations technology and mass
spectrometry instrumentation, with an emphasis ... 阅读全帖 |
|
f****6
发帖数: 4472 | 41 我是DMPK的PhD，主要做小分子LC/MS的方法学和小分子代谢，马上要毕业了。这周拿到
2个做intern的机会，都是做protein bioanalytics (triple quadrupole MS/MS) ，一
个BI，一个Merck。想问问大家觉得去哪里比较好？我也不知道哪里有可能转正。
PS：2年前在BI的另一个department做过intern，这次是通过employee refer，不去比
较伤人品；Merck是网投。谢谢，有包子。 |
|
a***r
发帖数: 146 | 42 On Tuesday, March 27, there was a serious failure in a high-pressure test at
CERN of a Fermilab-built “inner-triplet” series of three quadrupole
magnets in the tunnel of the Large Hadron Collider. The magnets focus the
particle beams prior to collision at each of four interaction points around
the accelerator.
Safety precautions were followed during the test, and no one was injured.
A full investigation of the failure is underway, but preliminary indications
are that structures supporting the in |
|
a***r
发帖数: 146 | 43 On Tuesday, March 27, a Fermilab-built quadrupole magnet, one of an “inner
triplet” of three focusing magnets, failed a high-pressure test at Point 5
in the tunnel of the LHC accelerator at CERN. Since Tuesday, teams at CERN
and Fermilab have worked closely together to address the problem and have
identified the cause of the failure. Now they are at work on a solution.
The asymmetric force generated by the pressure of the test broke the
supports in magnet Q1 that hold the magnet’s cold mass insi |
|
m********r
发帖数: 811 | 44 What is the shortest non-zero lenght, L, of a magnetic quadrupole that is
imaging in the horizontal plane, with omega=9 ? |
|
c******7
发帖数: 1177 | 45 Quadrupole Effects in Nuclear Magnetic Resonance of Solids
M.H. Cohena and F. Reifa, 5 , 321 (1957)
solid state physics |
|
发帖数: 1 | 46 需要知道同位素的核参数, such as
Fermi distribution parameter a:
Fermi distribution parameter c:
Mass of nucleus (in amu):
Nuclear spin (I) (in units of h / 2 pi):
Nuclear dipole moment (in nuclear magnetons):
Nuclear quadrupole moment (in barns):
RNT:
H:
HP:
NNNP:
3X! |
|
i*o
发帖数: 3 | 47 electric dipole radiation是因为Hamiltonian中的p*E项,
magnetic dipole radiation是因为角动量和磁场的相互作用.
两个应该能够同时发生, 但对于一般的物质, electric dipole radiation
要比magnetic dipole radiation强10^5, 所以一般只有在electric dipole
radiation是forbidden的时候才考虑magnetic dipole, 同时也要考虑
electric quadrupole了. 磁性材料就不清楚了. |
|
g*q
发帖数: 26623 | 48 The field is so weak, about 1/100,000 of what we can get from normal
conducting magnets.
p=B*Rho*e, E=pc for relativistic particles.
The earth's magnetic field should provide an energy of about 24GeV, which is
very very low compared to what we have in the storage rings.
Also, the storage rings need strong quadrupole/sextupole magnets for
focusing and enhancing stability, and quite lot more equipments. It's
impossible to be done in the space. |
|
