Durante mucho tiempo no había principios uniformes para la Atribución de nombres a los antibióticos https://antibioticos-wiki.es . Más a menudo se les llama por el nombre genérico o especie del producto, con menos frecuencia-de acuerdo con la estructura química. Algunos antibióticos se nombran de acuerdo con el lugar donde se asignó el producto.
Microsoft word - sfe535
Determination of Steroids in
A solution to these problems is to use an SFE instrument and method that simplifies the
Animal Tissues by
separation and recovery of trace level drug residues from an analyte/fat matrix. This
Supercritical Fluid
application describes a procedure for coupling SFE
Extraction and Inline
technology with an inline trapping technique to quickly and easily extract residue levels of steroids
Trapping
from animal tissue samples without co-extracting
Introduction Equipment
Applied Separations’ Spe-ed™ SFE-4
Teflon Inline Cartridge Holder- Cat. #7923
Materials
HPLC. Unfortunately, these methods are time
consuming, require large volumes of organic
solvent, and must be optimized for every new
Spe-ed Polypropylene Wool (Cat. #7952)
SFE is an alternative technique using supercritical
Carbon dioxide –SFC/SFE grade without
carbon dioxide to extract analytes from a variety of
matrices. SFE significantly reduces the use,
exposure to, and disposal of hazardous solvents,
while providing comparable extraction results to
There have been some problems identified with
using typical SFE methods to isolate drug residue
from tissue matrices. One of the main difficulties
is that when trace levels of residues are isolated
from fat tissue by SFE using CO2, fat is co-
extracted. If a modifier is used with CO2, the
N-Methyl-N- (trimethylsilyl)
resultant extract becomes more complex and the
desired analyte is more difficult to recover from
www.appliedseparations.com
Homogenize 5.0 g of tissue and freeze dry. When
Incubate this mixture for 30 minutes at 37 °C. Add
ready for extraction, blend freeze dried tissue with
1.0 ml of acidic buffer. (The acidic buffer is
3.5 g of Spe-ed Matrix. Add internal standard and
prepared by mixing 1.7 ml of hydrochloric acid
1 mL of water. Remove the end flanges of a 3 ml
(37%) with 98.3 ml of acetate buffer (2 mol 1-1).
SPE alumina cartridge and insert into an
Extract the mixture twice with 6 ml of TBME and
appropriately sized teflon holder. Close one end of
evaporate the combined extract to dryness under a
an extraction vessel, and place the cartridge/holder
gentle stream of nitrogen. Transfer the residue to a
into the vessel. Set the cartridge luer into the
derivatisation vial filled with 0.5 ml of ethanol.
outlet of the vessel. Next, place a plug of Spe-ed
Evaporate the ethanol and add 0.05 ml of HFBA-
Wool on top of cartridge/holder and compress with
acetone (1/4; v/v). Vortex mix the vial and
a stainless steel tamping rod. Pour the sample
incubate at 60 °C for 1 hr. Once incubation is
mixture of tissue and Spe-ed Matrix into the
complete, evaporate the reaction mixture to
extraction vessel and tamp down with rod. Fill the
dryness under a gentle stream of nitrogen at 50 °C.
remaining void in the extraction vessel with
Next, dissolve the derivatised residue in 0.025 ml
another plug of Spe-ed Wool, and then use a
of isooctane and transfer into a GC injection vial
stainless steel tamping rod to tightly pack the
with a micro-insert. Derivatisation method I can
vessel. Close vessel with an end-cap and perform
Extraction Conditions
Ethynylestradiol Ethynylestradiol-dAnalyte Recovery
When the extraction sequence is complete, remove
the SPE column and elute with 6 ml of methanol-
Derivatisation Method II:
Evaporate the second portion of the eluate under a
gentle stream of nitrogen in a water-bath at 50 °C.
Post-SFE Analysis
Add 2 mLs of water and mix in vortex for 30 s.
Divide the eluate into two equal portions.
Next, extract mixture twice with 6 ml of TBME.
Evaporate TBME and transfer residue into a
Derivatisation Method I:
derivatisation vial with 0.5 ml of ethanol.
Evaporate the solvent of the first portion and
Evaporate ethanol and add 25 µl of MSTFA-
dissolve the residue in 0.2 ml of alkaline
ammonium iodide-dithioerythritol (1000+2+4,
v/w/w). Mix vial for 30 s and incubate for 1 hour
(Prepare alkaline solution by dissolving 5.6 g of
potassium hydroxide in 100 ml of methanol).
www.appliedseparations.com
When incubation is complete, evaporate reaction
References
mixture to dryness under a gentle stream of
Stolker, A.; Zoontjes, P.; and van Ginkel, L. “The
nitrogen at 50 °C. Dissolve derivatised residue in
use of Supercritical fluid extraction for the
0.025 ml of iscoctane. Derivatisation method two
determination of steroids in animal tissues.”
The Analyst. 1998, 123, 2671-2676.
Nortestosterone Nortestosterone-d3 Methylboldenone Methylboldenone-d3 Norethandrolone Norgestrel Chlorotestosterone acetate Chlorotestosterone acetate-d3 Analysis GC-MS Results Validation results of SFE-GC-MS of Steroids from Fortified Bovine Muscle* Analyte Repeatability, laboratory Reproducibility RSD (%) (n=3) *(MSTFA Derivative) Conclusion The supercritical carbon dioxide extraction of steroids form animal tissue samples offers a viable alternative to solvent-based procedures. The accuracy and precision of the results were comparable to the standard method while extraction times were reduced. In addition, levels of detection were 2 ug/k for melengestrol acetate. www.appliedseparations.com
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MIR Guidelines Regarding Pre-Treatment of Patients Undergoing Contrast-Enhanced MRI 1. At the time of scheduling, it should be determined if the patient has had a prior reaction to either gadolinium-based (MR) or iodinated contrast agents. a. If there is no history of a prior reaction , then no pre-treatment is needed. b. If the patient has had a prior reaction to an MR contrast agen