Analysis of corticosteroids by high performance liquid chromatography–electrospray mass spectrometry

Direct identification of prohibited substances in cosmetics and foodstuffs using ambient ionization on a miniature mass spectrometry system

Significantly simplified work flows were developed for rapid analysis of various types of cosmetic and foodstuff samples by employing a miniature mass spectrometry system and ambient ionization methods. A desktop Mini 12 ion trap mass spectrometer was coupled with paper spray ionization, extraction spray ionization and slug-flow microextraction for direct analysis of Sudan Reds, parabens, antibiotics, steroids, bisphenol and plasticizer from raw samples with complex matrices. Limits of detection as low as 5 μg/kg were obtained for target analytes. On-line derivatization was also implemented for analysis of steroid in cosmetics. The developed methods provide potential analytical possibility for outside-the-lab screening of cosmetics and foodstuff products for the presence of illegal substances.

Liquid chromatography/tandem mass spectrometry for simultaneous determination of undeclared corticosteroids in cosmetic creams

RATIONALE

Undeclared corticosteroids in creams intended for frequent use might cause serious side-effects, especially in children. In order to prevent this or find the cause, it was essential to develop a method for quick detection and quantification of low levels of corticosteroids.

METHODS

Eleven corticosteroids were used in this study: prednisolone, methylprednisolone, prednisolone-21-acetate, fluocinolone acetonide, fluocinolone acetonide-21-acetate, hydrocortisone-21-acetate, dexamethasone, betamethasone, betamethasone dipropionate, clobetasol propionate and triamcinolone. Separation was achieved via liquid chromatography (LC), and mass spectrometric analysis was conducted by electrospray ionization triple-quadrupole mass spectrometry (MS/MS) in the multiple reaction monitoring mode using corticosterone as internal standard.

RESULTS

Good separation by using a gradient-elution LC/MS/MS method with run time of 25 min enabled the use of a segmented detection method and consecutive decrease in detection limits. The proposed method has been validated in the linearity range of 10-1000 ng/mL with coefficients of determination higher than 0.990. The method has shown to have very low limits of quantification (0.75-3 ng/mL) with satisfactory precision and accuracy for each of the corticosteroids.

CONCLUSIONS

An LC/MS/MS method for the rapid and simultaneous determination of low levels of eleven topical corticosteroids in creams was developed, optimized and validated. The proposed method can be used for testing of different products indicated for the treatment of atopic dermatitis, including "natural products", and "herbal creams" with "miraculous effects".

Screening of counterfeit corticosteroid in creams and ointments by NMR spectroscopy

It has been shown that NMR spectroscopy is an effective analytical method to rapidly screen creams and ointments for counterfeit corticosteroids. Extraction and NMR procedures have been developed. Ten over the counter creams and ointments sold in health care shops were screened and two creams were found to contain counterfeited corticosteroids.

Ultra-Sensitive Quantification of Corticosteroids in Plasma Samples Using Selective Solid-Phase Extraction and Reversed-Phase Capillary High-Performance Liquid Chromatography/Tandem Mass Spectrometry

Low-dose corticosteroids may provide a favorable benefit/risk ratio for many therapeutic applications. However, the extremely low plasma drug concentrations achieved, in conjunction with the insufficient sensitivity/ selectivity of current analytical methods, renders the evaluation of corticosteroid pharmacokinetics (PK) a significant challenge under such conditions. Furthermore, targeted therapeutic strategies involving administration by inhalation or intraocular injection could result in very low but sustained systemic corticosteroid concentrations, which must be quantified to determine potential side effects. Here we describe a robust method for the ultrasensitive quantification of corticosteroids in plasma samples. This was achieved by the combination of a selective solid-phase extraction (SPE) with a highly sensitive capillary LC (microLC)-MS/MS analysis. SPE washing and elution conditions were optimized so that target drugs are selectively extracted from plasma. By eliminating most undesirable compounds from the sample matrix, this selective SPE procedure enabled a high sample loading volume on the microLC column without compromising chromatographic performance and operational robustness and helped to achieve ultralow detection limits for the corticosteroids in plasma. The effect of microLC separation on the signal-to-noise ratio of corticosteroid peaks in plasma samples was investigated. It was found that with sufficient microLC separation, sensitivity was improved because of a decrease in matrix effects and the removal of endogenous interferences. Detection limits of four clinically important corticosteroids (budesonide, dexamethasone, triamcinolone acetonide, and dexamethasone acetate) ranged from 0.2 to 1 pg/mL in plasma, and linearity was good for all drugs in the range of 5-5000 pg/mL. Accuracy was 88-107% and the variation (CV%) was 2.3-11.1%. A limit of quantification (LOQ) of 5 pg/mL was validated for all four compounds. We applied this method to quantify the low levels of triamcinolone acetonide (TACA) in porcine plasma following suprachoroidal administration, which is necessary to estimate systemic drug exposure resulting from this novel clinical approach for treating inflammatory diseases of the eye. TACA in plasma could be quantified at low pg/mL levels for up to 90 days posttreatment. To our knowledge, this is the first practical analytical approach that can monitor plasma corticosteroids after intraocular administration, given the ultralow plasma concentrations achieved. In summary, this strategy enables PK analysis of corticosteroids in treatment regimens that result in extremely low systemic concentrations, and the approach can be extended for the sensitive quantification of other drugs.

High-performance liquid chromatography analysis of anti-inflammatory pharmaceuticals with ultraviolet and electrospray-mass spectrometry detection in suspected counterfeit homeopathic medicinal products

A simple high-performance liquid chromatography (HPLC) method with both ultraviolet (UV) and electrospray ionisation mass spectrometry (ESI-MS) detection has been developed for the determination of seven pharmaceuticals in counterfeit homeopathic preparations. Naproxen, Ketoprofen, Ibuprofen, Diclofenac, Piroxicam, Nimesulide and Paracetamol were separated by reversed phase chromatography with acetonitrile-water (0.1% acetic acid) mobile phase, and detected by UV at 245 nm and by ESI-MS in negative ionisation mode with the exception of Paracetamol which was detected in positive ionisation mode. Benzoic acid was used as internal standard (IS). This method was successfully applied to the analysis of homeopathic preparations like mother tinctures, solutions, tablets, granules, creams, and suppositories. Linearity was studied with UV detection in the 50-400 microg mL(-1) range and with ESI-MS in the 0.1-50 microg mL(-1) range. Good correlation coefficients were found in both UV and ESI-MS. Detection limits ranged from 0.18 to 41.5 ng in UV and from 0.035 to 1.00 ng in ESI-MS.