Помогите с микроанализом!!!

[Wisy]

Здрасте!
Нам на группу в универе дали задание по количественному органическому микроанализу. Не имеея порядочных знакомых с литературой (библиотека в универе по этому поводу вообще молчит), я решил обратится к Всемирной. Однако и тут меня постигло разочарование: поисковики и известная мне электронная научная библиотека ничего внятного не показывают!!! Поэтому: пожалуйста, посоветуйте, куда мне податься, или, если у Вас есть такое желание, поделитесь книжечкой (хоть какой-нибудь!). Я буду очень благодарен!

Честно говоря, больше всего меня интересует следующая тема: "Определение галогенов и серы по Шенигеру". Поделитесь, пожалуйтесь, своими соображениями! ... только не затягивайте, а то мне в конце недели уже сдавать материал надо бы-бы-будет....

[eukar]

Для начала можно в местной библиотеке посмотреть книги по аналитике: http://www.chemport.ru/index.php?cid=31

[Wisy]

хех! тама я тоже был...

[eukar]

И что, в книгах "аналитическая химия..." (серы, хлора, брома) интересующий вопрос не поднимается?

[slavert]

Bibliographic Information

The Schoeniger combustion. III. Microdetermination of bromine, iodine, phosphorus, carbon, arsenic, boron, mercury, and other metals. Soep, H. Mededel. Vlaam. Chem. Ver. (1961), 23 103-32. Journal language unavailable. CAN 56:42109 AN 1962:42109 CAPLUS

Abstract

cf. CA 54, 4253b.--In the mercurimetric Cl or Br detn. according to Demoen, 0.05 meq. of halogen comp. is combusted in a Schoeniger bottle. The halogen is absorbed in 10 ml. 0.02N NaOH and 2 drops 30% H2O2, the stopper and spiral are rinsed with 10 ml. iso-PrOH. Four ml. 0.1N HNO3, 40 ml. iso-PrOH, and 5 drops indicator (0.6 g. diphenylcarbazone in 100 ml. iso-PrOH) are added, and the soln. is titrated with 0.01N Hg(NO3)2 to a pink-violet color. For the detn. of I, 10% N2H4 is added dropwise to complete decolorization before addn. of iso-PrOH and HNO3. If Br is to be detd. in the presence of Cl, oxidn. of Br- to BrO3 is suitable, but I will also be included. The oxidn. of Br- to free Br is only reliable if Cl-:Br- = <5:1; I- interferes. The literature on the detn. of I in the presence of Cl (Leipert titration, CA 24, 2398), of P (as BiPO4 or MgNH4PO4), C, H, As, B, Hg, Zn, Cd, Mg, Se, Pb, Br, Ni, S, and F is surveyed. 143 references.

[slavert]

The Schoeniger flask is named for the developer of the procedure:

Professor Wolfgang Schoeniger, a very competent microanalyst.

The original was nothing but an Erlenmeyer flask and it was used for
determining elements in organic compounds. Specifically chlorine but
also adapted for other elements.

Apparatus:

1. One Erlenmeyer flask (actually more than one because they exploded
rather frequently)
2. One (one hole) rubber stopper for the flask. (Reusable after the
flask explosions)
3. One glass rod with a platinum coil at the end stuck through the
one hole rubber stopper so that when the stopper was inserted into the
flask the Pt coil was a couple centimeters above the bottom. (Usually
reusable after explosions)
4. Supply of oxygen gas.

That answered all of your questions except for references but I
suppose you would like to know how to risk life and limb with that
collection of stuff.

Procedure:

1. Add a few ml of dilute NaOH to a clean flask.
2. Weigh a few milligrams of sample onto a small piece of ashless
filter paper. (Use the good stuff that has a low blank but determine
what the blank is.) If you weigh too large a sample then be certain
that extra flasks are available.
3. Fold the filter paper around the sample and place the folded paper
in the Pt coil.
4. Fill the flask with oxygen.

These next steps should be done rapidly with no hesitation between
steps. You might want to make a few practice runs before wasting a
sample.

5. Ignite the folded paper, insert the flaming paper into the flask,
secure the stopper by pressing firmly, invert the flask so the
solution forms a seal, shield eyes with other hand and grit your
teeth.
6. If everything goes right you will get a clean burn and a bit of
white ash will slowly drift down.
7. Shake flask for a few minutes to absorb chloride e.g. and proceed
with analysis.

[slavert]

http://www.tecnologia-aplicada.com/prod ... ombustion'

[slavert]

Schöniger oxidation
From Wikipedia, the free encyclopedia.
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In chemistry, the Schöniger oxidation (also known as the Schöniger Flask Test) is a test in qualitative elemental analysis, developed by Wolfgang Schöniger.

sample (with C,N,S,H,X) + oxygen (O2) + NaOH → Na+X- + Na+NO-2 + Na+2SO-3

X = Cl, Br, F, I

It allows quantitative determination of elemental chlorine, nitrogen and sulfur in a sample.

PS Благодарность за найденную информацию прошу переводить на мой счет в Credit Suisse

[terrachem]

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