Silvia A. Coran

Improving gas chromatographic determination of residual solvents in pharmaceuticals by the combined use of headspace solid-phase microextraction and isotopic dilution

Cyclohexane and toluene were gas chromatographically determined via headspace solid-phase microextraction both in ketoprofen drug substance and ketoprofen capsules by a procedure relying on isotopic dilution (ID), an analytical tool derived from mass spectrometry (MS). This approach, using an internal standard method, gave mean precision and accuracy (RSD 2.56%, 2.97% and bias 0.21%, -0.99% for cyclohexane and toluene, respectively) not obtainable by the more commonly used external standard ones in the presence of real sample matrices. Optimisation of the operative conditions was also supported by experimental design. More generally, the proposed method, exploiting ID without resort to the costly MS instrumentation, could be recommended whenever opportune deuterated analogues of the target analytes and GC capillary columns able to separate all the peaks involved are ready available on the market.

Complete assignment of the 1H and 13C NMR spectra of secoisolariciresinol diglucoside, a mammalian lignan precursor isolated from Linum usitatissimum

A convenient isolation and purification protocol for secoisolariciresinol diglucoside (1), a precursor of the biologically active mammalian lignans enterolactone and enterodiol, from flax seed is reported together with an extensive 1D‐ and 2D‐NMR study (GE‐HSQC, GE‐HMBC and NOESY) leading to its definitive characterization as 2,3‐bis[(4‐hydroxy‐3‐methoxyphenyl)methyl]‐1,4‐butanediyl bis‐[R‐(R*,R*)]‐β‐D‐glucopyranoside. Copyright

Optimization and validation of a CZE method for rufloxacin hydrochloride determination in coated tablets.

A simple and rapid capillary electrophoresis method with UV detection was developed and validated for the determination of rufloxacin hydrochloride in coated tablets. An experimental design strategy (Doehlert design and desirability function) allowed the analytical parameters to be simultaneously optimized in order to determine rufloxacin hydrochloride with high peak area/migration time ratio, good efficiency and short analysis time. Optimized analyses were run using boric acid 0.10 M adjusted to pH 8.8 as BGE and setting voltage and temperature at 18 kV and 27 degrees C, respectively. Pefloxacin mesylate was used as internal standard and run time was about three minutes. The method was validated for the drug substance and the drug product according to the ICH3 guidelines. Robustness was tested by experimental design using an eight-run Plackett-Burman matrix.

Development of a densitometric method for the determination of cephalexin as an alternative to the standard HPLC procedure

A HPTLC-densitometric method was developed in order to obtain a reliable procedure for routine analysis of cephalexin in pharmaceutical formulations. Optimization of TLC conditions for the densitometric scanning was reached by eluting HPTLC silica gel plates in an horizontal developing chamber. Quantitation of cephalexin was performed in single beam reflectance mode by using a computer-controlled densitometric scanner and applying a five-point calibration. A linear regression has been found in the 200-1000 ng range. The setup method is precise, reproducible and accurate. Recovery was also assessed by comparison with the HPLC USP XXIII alternate method. In this case HPTLC-densitometry appears worth of consideration as being relatively inexpensive and time-saving (up to 12 samples can be determined simultaneously in less than 15 min with a solvent consumption of about 15 ml). The results suggest that the proposed method may be used in place of HPLC for the routine quantitation of cephalexin in both pure and dosage forms.

Crucial aspects of high performance thin layer chromatography quantitative validation. The case of determination of rosmarinic acid in different matrices.

A new HPTLC method was envisaged to determine rosmarinic acid (RA) in different matrices with the aim of testing the influence of optimizing the main HPTLC operative parameters in view of a more stringent validation process. HPTLC LiChrospher silica gel 60 F254s, 20 cm × 10 cm, plates with toluene:ethyl formate:formic acid (6:4:1, v/v) as the mobile phase were used. Densitometric determinations were performed in reflectance mode at 330 nm. The method was validated giving rise to a dependable and high throughput procedure well suited to routine applications. RA was quantified in the range of 132-660 ng with RSD of repeatability and intermediate precision not exceeding 2.0% and accuracy within the acceptance limits. The method was tested on several commercial preparations containing RA in different amounts.

Profiling of components and validated determination of iridoids in Gardenia Jasminoides Ellis fruit by a high-performance-thin-layer- chromatography/mass spectrometry approach

A novel method was set up with the aim to obtain a simultaneous cross comparative evaluation of different Gardenia Jasminoides Ellis fruits by the HPTLC fingerprint approach. The main components among the iridoid, hydroxycinnamic derivative and crocin classes were identified by TLC-MS ancillary techniques. The iridoids geniposide, gardenoside and genepin-1-β-d-gentiobioside were also quantitated by densitometric scanning at 240nm. LiChrospher HPTLC Silica gel 60 RP-18 W F254, 20cm×10cm plates with acetonitrile: formic acid 0.1% (40:60 v/v) as the mobile phase was used. The method was validated giving rise to a dependable and high throughput procedure well suited to routine applications. Iridoids were quantified in the range of 240-1140ng with RSD of repeatability and intermediate precision between 0.9-2.5% and accuracy with bias 1.6-2.6%. The method was tested on six commercial Gardenia Jasminoides fruit samples.

Characterization of Sanguinaria canadensis L. fluid extract by FAB mass spectrometry

Positive-ion fast atom bombardment mass spectrometry was used for the rapid characterization of commercial Sanguinaria canadensis L. fluid extracts. Quaternary and non-quaternary benzophenanthridine alkaloids afford persistent peaks due to [M]+ and [M+H]+ ionic species, respectively, and their relative abundances are in good agreement with previously reported per cent analytical data. The procedure allowed sanguinarine, chelerythrine, chelirubine, sanguilutine, protopine, allocryptopine and the isomers sanguirubine and/or chelilutine to be effectively detected by means of persistent and intense peaks in all the samples examined.

Direct quantitation of antiseptic quaternary ammonium compounds by fast atom bombardment mass spectrometry

The medicinally important quaternary ammonium salts benzyldimethyltetradecylammonium chloride (BDTA), cetylpyridinium chloride and benzethonium chloride, all afford, under fast atom bombardment (FAB) mass spectrometric conditions, abundant and persistent [M-Cl]+ species usefully amenable to quantitative analysis with the aid of thioglycerol as a liquid FAB matrix. The use of BDTA as an internal standard allowed a direct, precise and accurate determination of cetylpyridinium and benzethonium chlorides, either as pure samples or in dosage forms, in the concentration range 0.05-2 mg/ml.

Validated determination of primulasaponins in primula root by a high-performance-thin-layer-chromatography densitometric approach.

A novel HPTLC-densitometric method was developed for separation and quantitation of primulasaponin I and II in different matrices. HPTLC silica gel 60 F254(S), 20 cm × 10 cm, plates with ethyl acetate:water:formic acid (5:1:1 v/v) as the mobile phase were used. Densitometric determinations were performed in reflectance mode at 540 nm after derivatization with vanillin reagent. The method was validated giving rise to a dependable and high throughput procedure well suited to routine applications. Primulasaponins were quantified in the range of 150-450 ng with RSD of repeatability and intermediate precision between 0.8 and 1.4% and accuracy within the acceptance limits. The method was tested on commercial herbal medicinal preparations claiming to contain primula root extract.

Selective determination of aloin in different matrices by HPTLC densitometry in fluorescence mode

A novel method based on the fluorescence excited solely on aloin by a H₃BO₃ derivatizing procedure, allowed its rapid and selective determination among the co-occurring components in a variety of complex matrices as several Aloes dried extracts and related commercial products. HPTLC LiChrospher silica gel 60 F254S, 20 cm x 10 cm, plates with ethyl formate: CH₃OH:H₂O (100:14.5:10, v/v) as the mobile phase were used. Densitometric determinations were performed in fluorescence mode, exciting wavelength 365 nm, optical filter K540 after derivatization with H₃BO₃. The method was validated giving rise to a dependable and high throughput procedure well suited to routine application. Aloin was quantified in the range of 110-330 ng with RSD of repeatability and intermediate precision not exceeding 2.3% and accuracy inside the acceptance limits.