GLC Assay of Conjugated Estrogen Formulations

Quantitative determination of conjugated estrogens in formulations by capillary GLC

“…Quantitation of conjugated estrogens in some available formulations provided the data shown in Table 11; unlike with previous methods (3,4), the quantity of 17P-estradiol now can be determined with certainty.…”

“…Many methods have attempted to resolve all of the components of this relatively complex mixture, including paper chromatography (7-9), TLC (10)(11)(12)(13)(14), high-performance liquid chromatography (15)(16)(17)(18), and GLC (2)(3)(4)(19)(20)(21)(22)(23). The identification test requires a prominent peak for one steroid, 17a-dihydroequilin, and this substance probably is the steroid monitored by the previous USP ( 5 ) identification test.…”

“…BACKGROUND A consequence of the broad and nonquantitative specifications for the major and minor steroids is that compendia1 standards may not ensure pharmaceutical equivalence. This impurity, if not removed prior to analysis, would interfere with both GLC methods (3,4). For example, 17P-estradio1, although a minor component, exhibits 12 times the potency of the major steroid, estrone (6).…”

“…More rigorous specifications for the indi- vidual steroids are needed, especially in view of the widely varying potencies of each steroid in the mixture. This interference has necessitated the removal of this impurity by a lengthy extraction step (4). Many methods have attempted to resolve all of the components of this relatively complex mixture, including paper chromatography (7-9), TLC (10)(11)(12)(13)(14), high-performance liquid chromatography (15)(16)(17)(18), and GLC (2)(3)(4)(19)(20)(21)(22)(23).…”

Resolution of equine estrogens using glass capillary columns

“…Most reported methods, however, are of limited usefulness for completely separating and quantifying equine estrogen mixtures.The twodifficult pairswhich could not be resolved by GLC are 17~-estradiolll7a-dihydroequilin and estronel equilin. Packed column gas-liquid chromatography (GLC) has been employed with some success in resolving most of the components when diethylene glycol succinate (DEGS) or cyanopropylphenylmethyl silicone (OV-225) was used as the stationary phase [15][16][17].Trimethylsilyl (TMS) ethers of most of the steroids present in the mixture, except 170-estradiol and 17a-dihydroequilin, separated well on the DEGS column but the useful lifetime of the column is generally short and it has an upper temperature limit of 195OC. As a result, the peaks obtained are broad and the time required for chromatography is long.…”