Separation of Phenothiazine
Derivatives on Basic Aluminum Oxide TLC Plates
Phenothiazine salts migrate little, if at all, on acid aluminum oxide plates. On
layers of neutral and more particularly basic Aluminum
Oxide TLC layers, good migration is achieved by virtue of exchange processes (similar
to those with alkaloid salts on aluminum oxide layers). Benzene is a suitable developing
solvent with the addition of 5% acetone. Dragendorff reagent is used as a developer. If
the acetone content is increased, the Rf-value becomes greater.
||Pure Substance Rf-value
Identification of Methaquallone in tissue
and Blood via TLC and Mass Spectrometry
It is difficult to distinguish between methaqualone and
substances with similar Rf-values only via thin-layer chromatography. If this problem
arises, methaqualone may be identified by the mass spectrum of the substance adhering to
Chromatographic examination of autopsy-blood extract contaminated
with decomposition products of hemoglobin, was carried out on Silica Gel F TLC, using
chloroform/acetone 9 + 1 (v/v) and Dragendorff reagent, and showed a substance spot at Rf
The reference substances showed the following Rf values:
Methaqualone = 0.84
Glutethimide = 0.78
For improved differentiation, the spot detected on the plate under
UV-light was scraped off, the sample was extracted with diethyl ether, decanted, enriched
in a small amount of silica gel, and placed directly into the ion-source of the mass
spectrometer. The attached figure shows the mass spectra of the sample and of the pure
Quantities of about 15-20 ug. of methaqualone can be reliably
detected by means of this procedure.
After filtration, the tartaric filtrate is extracted with ether and
is dried over sodium sulfate and evaporated. Urine, after addition of hydrochloric acid
(pH 3-4), is exhaustively extracted by ether. The ether is dried over sodium sulfate,
treated with a small amount of active carbon and Aluminum Oxide Neutral, Act. 1, for a
short time, and finally evaporated.
The residue is chromatographed on Silica Gel GF TLC (Cat#: 83111) with the solvent chloroform/acetone 9:1.
For the detection of the substance spots the thin-layer chromatograms are sprayed with
mercurous-(I)-nitrate, Zwikkers reagent, and mercurous-(II) sulfate/diphenylcarbazone.
Two samples each of the test material are spotted adjacent to each
other. Both samples are primarily evaluated under UV-light. One sample is used for a color
test and the corresponding zones of the second sample for the mass spectrometry. For this
purpose the single spots are scraped off, extracted by ether, and the ether is decanted
and evaporated. The enriched substances are brought directly into the ion source of the
mass spectrometer. They allow mass spectra, which can be reliably evaluated.
Detection of Barbituric Acid Derivatives by
TLC and Mass Spectrometry in Autopsy Material
The following substances could be
The identification of about 20-25 ug of 12
barbiturates as well as Carbromal and Bromisoval, which are often present in
pharmaceutical specialties together with 4 barbituric acids, is possible by means of a
combination of thin-layer chromatography and mass spectrometry.
Autopsy material is extracted with a solution of tartaric 5 acid in
ethanol after homogenization. The ethanol is evaporated and the residue dissolved by warm
Identification of Selected Pesticides via
For the detection of pesticide residues in food many
methods are published, which in most cases require a considerable amount of apparatus,
reagents and time. The separation technique should allow quick detection of the quantity
of pesticide residue without much expenditure, and only with small amounts of solvents.
This preliminary data will then dictate whether a precise determination of the identified
pesticide should follow or whether the approximate value obtained by spot comparison is
Summary of 15 substances to be detected include:
- Chlorinated hydrocarbons:
DDT, dieldrin, aldrin, lindane, endsulfan (I and II) as well as pentachloronitrobenzene
(PCNB) and tetrachloronitrobenzene (TCNB)
- Phosphoric acid esters
Parathion, dimethoate, bromophos
Pentachloronitrobenzene (PCNB), tetrachloronitrobenzene (TCNB), dichlofluanid as well as
its metabolite DMSA
IPC (N-phenyl isopropyl carbamate; propham)
The plant material is macerated with hexane-isopropyl alcohol(70:30); active substances
are transferred into the hexane phase. After drying and removal of pigments a combination
column (Alumina Basic, Activity V, and Na2SO4 on top) the yellow
extract yield is directly spotted on a thin layer plate. Length of run always 17 cm. - If
too much wax is present, it should first be treated with acetonitrile. The sensitivity is
usually at 2-6 ug of each active substance, but with DDT even 0.5 ug can be detected.
- Chlorinated hydrocarbons are separated on Silica Gel G TLC (Cat#: 83101) in hexane/chloroform
(9:1). Detection by spraying with Ag/NO3.
- Phosphoric acid esters are separated on Silica Gel G TLC (Cat#: 83101) or on TLC-plates,
pre-coated with Silica Gel F-254 (Cat#: 84111) in
- Fungicides, bacteriostatics, and herbicides are separated in the same
way as P-esters on TLC plates, pre-coated with Silica
Gel F-254 (Cat#: 84111), then diazotised, coupled, and the color products evaluated in
UV and visible light.
Thin-Layer Chromatography of
Selected Indanol Derivatives of Pharmaceutical Interest
7-Chloro-4-hydroxy Indan, 4-hydroxy-1,5,7-trimethyl Indan, and other
indanol derivatives demonstrate excellent bactericidal, fungicidal, and amebicidal
properties. Thin-layer chromatography was found to be ideal for qualitative and
quantitative control of these substances in pharmaceutical specialties.
Silica Gel GF TLC (Cat# 83111)
||Chloroform/abs. alcohol 4:1:1
After development, the thin-layer plates should
be dried. Under UV 254nm the substances appeared as dark spots against the greenish
fluorescent background. If the fluorescent indicator is not available, the plates should
be sprayed with an aqueous potassium permanganate solution (1%): yellow spots indicate the
position of the various compounds on violet brown background.
||Rf- Values with various
Solvent systems on Silica Gel GF
|4-Hydroxy-1,5,7 - trimethyl Indan