Normal phase-liquid chromatography-tandem mass spectrometry with atmospheric pressure photoionization for the purity assessment of 17β-estradiol

Methods for the SI-traceable value assignment of the purity of organic compounds (IUPAC Technical Report)

The “purity” of an organic compound typically refers, in practice, to an assignment of the mass fraction content of the primary organic component present in the material. The “purity” value of an organic primary calibrator material is the ultimate source of metrological traceability of any quantitative measurement of the content of that compound in a given matrix. The primary calibrator may consist of a Certified Reference Material (CRM) whose purity has been assigned by the CRM producer or a laboratory may choose to value-assign a material to the extent necessary for their intended application by using appropriately valid methods. This report provides an overview of the approach, performance and applicability of the principal methods used to determine organic purity including mass balance, quantitative NMR, thermal methods and direct-assay techniques. A statistical section reviews best practice for combination of data, value assignment as the upper limit values corresponding to 100 % purity are approached and how to report and propagate the standard uncertainty associated with the assigned values.

Rapid Identification of 44 Steroids in Human Urine Samples using HPLCESI- QTOF-MS

Objective:

Detailed analysis of un-processed and un-derivatized free and conjugated urinary steroids is useful to avoid miscalculations and to diagnose sports doping and adrenal problems, including abnormal steroidogenesis, congenital deficiency of related enzymes, cancer, and other disease conditions. Hence, the present study was conducted to develop a soft ionization method to identify the maximum number of urinary steroids using ultra-performance liquid chromatography coupled with quadrupole time of flight mass spectrometer (HPLC–Q-TOF-MS).

Material and Methods:

HPLC–Q-TOF-MS was carried out for the qualitative detection of steroids and their conjugates in urine samples. The method provides high sensitivity and fast analysis of steroids and their glucuronides without hydrolysis or sample preparation or extraction of steroids.

Results:

Using the method, 44 steroids belonging to C-18, C-19, and C-21 classes and their conjugates were resolved and identified using positive and negative modes of ionizations by their characteristic ionization and collision energy induced dissociation behaviors.

Conclusion:

The method is time-saving and good to compare samples from different peoples with control or healthy ones as it does not require any kind of pre-treatment or sample processing. It provides a complete picture of steroids metabolism and catabolism. It can be good for doping control or to explore the effects of other drugs. However, in qualitative analysis, one may miss the significant information unless direct methods of steroids analysis to be employed.

Current developments in LC-MS for pharmaceutical analysis

Liquid chromatography (LC) based techniques in combination with mass spectrometry (MS) detection have had a large impact on the development of new pharmaceuticals in the past decades.

A simple and highly selective electrochemical label-free aptasensor of 17β-estradiol based on signal amplification of bi-functional graphene

In the present work, a convenient signal-on electrochemical label-free aptasensor for 17β-estradiol (E2), a typical steroidal hormones endocrine disrupting chemicals, was proposed. 6-mercapto-1-hexanol (MCH) self-assembled monolayer (SAM) modified Au (MCH/Au) electrode was used as the substrate electrode. Graphene is used with bi-functions, not only to adsorb E2 binding aptamer, serving as the recognition element to E2, but also to be assembled onto MCH/Au electrode when sensing E2, to controllably turn on the electron transfer (eT), and further indicate the signal to E2 concentration. With the synergistic effect of DNase I enzyme, highly sensitive detection of E2 was achieved at this aptasensing system, with a linear range from 0.07 to 10 pM and a detection limit of 50 fM. An outstanding selectivity towards E2 was proven for the sensing system by simultaneously detecting 100-fold potential co-existing interferences. The stability and reproducibility were also evaluated to be satisfactory. Spiked real water analysis further indicated its reliability and potential in practical environmental monitoring.