An HPLC method for the determination of the free cortisol/cortisone ratio in human urine

Serially coupled column liquid chromatography: An alternative separation tool

Despite the rapid development of liquid chromatography (LC) in recent decades, it remains a challenge to achieve the desired chromatographic separation of complex matrices using a single column. Multi-column LC techniques, particularly serially coupled column LC (SCC-LC), have emerged as a promising solution to overcome this challenge. While more attention has been focused on heart-cutting or comprehensive two-dimensional LC, reviews specifically focusing on SCC-LC, which offers advantages in terms of precision and facile instrumentation, are scarce. Here, our concerns are devoted to the progress summary regarding the instrumentation and applications of SCC-LC. Emphasis is placed on column selection aiming to enlarge peak capacity, selectivity, or both through the optimization of combination types (e.g. RPLC-RPLC, -RPLC-HILIC, and achiral-chiral LC), connection devices (e.g. zero dead volume connector, tubing, and T-type connector), elution program (i.e. isocratic or gradient) and detectors (e.g. mass spectrometer, ultraviolet detector, and fluorescence detector). The application of SCC-LC in pharmaceutical, biological, environmental, and food fields is also reviewed, and future perspectives and potential directions for SCC-LC are discussed. We envision that the review can give meaningful information to analytical scientists when facing heavy chromatographic separation tasks for complicated matrices.

An Immunosensor for the Determination of Cortisol in Serum and Saliva by Array SPRi

Cortisol is a hormone which plays an essential role in the immune, endocrine, cardiovascular, renal and skeletal systems. Its level increases in response to stress, illness, injury or exhaustion, and it is therefore a significant diagnostic biomarker of stress. An immunosensor for the determination of cortisol by SPRi array was developed. The receptive part of the immunosensor is mouse monoclonal antibody against cortisol, immobilized via cysteamine linker. The optimum pH of the immunosensor is 7.4, and the optimum concentration of the antibody is 50 ng mL^-1. The immunosensor is specific for cortisol, and its linear response ranges from 0.20 ng mL^-1 (LOQ) to 8 ng mL^-1. The precision of the determination was between 3.1% and 3.3%, and the recovery between 99% and 102%. The immunosensor was validated by simultaneous determination of cortisol in serum and saliva samples by a standard method, with good agreement between the results.

Molecularly Imprinted Polymer-Based Sensor for Electrochemical Detection of Cortisol

As a steroid hormone, cortisol has a close relationship with the stress response, and therefore, can be used as a biomarker for early detection of stress. An electrochemical immunosensor is one of the most widely used methods to detect cortisol, with antibodies as its bioreceptor. Apart from conventional laboratory-based methods, the trend for cortisol detection has seemed to be exploiting antibodies and aptamers. Both can provide satisfactory performance with high selectivity and sensitivity, but they still face issues with their short shelf life. Molecularly imprinted polymers (MIPs) have been widely used to detect macro- and micro-molecules by forming artificial antibodies as bioreceptors. MIPs are an alternative to natural antibodies, which despite demonstrating high selectivity and a low degree of cross-reactivity, often also show a high sensitivity to the environment, leading to their denaturation. MIPs can be prepared with convenient and relatively affordable fabrication processes. They also have high durability in ambient conditions, a long shelf life, and the ability to detect cortisol molecules at a concentration as low as 2 ag/mL. By collecting data from the past five years, this review summarizes the antibody and aptamer-based amperometric sensors as well as the latest developments exploiting MIPs rather than antibodies. Lastly, factors that can improve MIPs performance and are expected to be developed in the future are also explained.

Sweat Cortisol and Cortisone Determination in Healthy Adults: UHPLC-MS/MS Assay Validation and Clinical Application

A simple and effective ultra-high-performance liquid chromatography assay linked to tandem mass spectrometry (UHPLC-MS/MS) for measuring cortisol and cortisone levels in human sweat has been developed and validated. A noninvasive world standard sweat collecting equipment was utilized to collect samples. The samples were analyzed using an Atlantis dC18 (2.1 × 100 mm, 3 μm) column with a 2 mM ammonium acetate and acetonitrile (1 : 1, v : v) mobile phase. In an isocratic condition, the mobile phase was delivered at a flow rate of 0.3 ml/minute. A positive electrospray ionization interface with multiple-reaction monitoring mode was used to provide simultaneous quantification of cortisol, cortisone, and internal standard at transitions of 363.11 to 121.00, 361.18 to 163.11, and 367.19 to 121.24, respectively. The method was validated for cortisol and cortisone determination over a concentration range of 0.5–50 ng/mL The detection limits for cortisol and cortisone in human sweat were 0.3 and 0.2 ng/ml, respectively. The interday coefficients of variation of cortisol and cortisone were ≤8.5% and ≤10.01%, whereas bias was in the range from −7.9% to 2.1% and from −4.3% to 3.0%, respectively. The assay was successfully applied to evaluate the cortisol-to-cortisone ratio in sweat samples collected from healthy adult volunteers.

Perceived stress, depressive symptoms, and cortisol-to-cortisone ratio in spot urine in 6878 older adults

BACKGROUND

Late life depression and perceived stress could influence disease pathways via reduced 11β-HSD2 activity, particularly given suggestions that reduced 11β-HSD2 activity, which is reflected in the cortisol-to-cortisone ratio, is a risk factor of disease. To date, however, examination of the relationship between the cortisol-to-cortisone ratio and perceived stress or depressive symptoms is insufficient.

METHODS

We examined the cross-sectional association of the cortisol-to-cortisone ratio with perceived stress and depressive symptoms, and analyzed whether cortisol levels modify this association, in 6878 participants aged 45-74 years. Cortisol and cortisone in spot urine were measured using liquid chromatography-mass spectrometry. Perceived stress during the past year was measured using a self-reported questionnaire. Depressive symptoms were evaluated using the Zung Self-Rating Depression Scale. Analyses were performed with adjustment for age, sex, lifestyle factors (smoking habit, alcohol consumption, physical activity, and sleeping hours), and physical health factors (body mass index [kg/m²] and medical history [diabetes, hypertension, and medication for hyperlipidemia or corticosteroids]).

RESULTS

Cortisol-to-cortisone ratio and cortisol were positively associated with perceived stress (% change: 2.33, P_trend = 0.003; and 4.74, P_trend = 0.001, respectively), but were not significantly associated with depressive symptoms. Further, the relationship between cortisol-to-cortisone ratio and perceived stress was modified by cortisol level and sex: the positive association between perceived stress and the cortisol-to-cortisone ratio was more evident in subjects with lower cortisol levels (P_interaction = 0.009) and in men (P_interaction = 0.026).

CONCLUSIONS

These findings suggest that the cortisol-to-cortisone ratio in spot urine may be a useful marker for non-acute perceived stress in daily life against a possible background of reduced 11β-HSD2 in older adults.

Nanoantenna-assisted plasmonic enhancement of IR absorption of vibrational modes of organic molecules

Nanoantenna-assisted plasmonic enhancement of IR absorption and Raman scattering was employed for studying the vibrational modes in organic molecules. Ultrathin cobalt phthalocyanine films (3 nm) were deposited on Au nanoantenna arrays with specified structural parameters. The deposited organic films reveal the enhancement of both Raman scattering and IR absorption vibrational modes. To extend the possibility of implementing surface-enhanced infrared absorption (SEIRA) for biological applications, the detection and analysis of the steroid hormone cortisol was demonstrated.

Simultaneous determination of 30 hormones illegally added to anti-ageing functional foods using UPLC-MS/MS coupled with SPE clean-up

A novel analytical method employing solid-phase extraction (SPE) coupled with ultra-high-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was developed for the simultaneous determination of 30 hormones in anti-ageing functional foods (capsules, powders and tablets). The analytes were extracted with acetic acid-acetonitrile (1-99 v/v), methanol and acetone, respectively. The extract was purified using a combined column, followed by analyte detection with electrospray ionisation in positive- or negative-ion modes. The results indicated that the 30 compounds had good linear correlations in the range of 1-1000 μg kg⁻¹, and the correlation coefficients were above 0.99. The limits of detection (LOD) and limits of quantification (LOQ) were 0.03-2 and 0.1-5 μg kg⁻¹, respectively. The average recovery of 30 compounds at the three spiked levels varied from 74.7% to 124.1%, and the relative standard deviation (RSD) was 2.4-15.0%. This method was applied to the analysis of hormones in 14 real samples of which seven hormones (such as estrone, dienestrol) were detected in four samples, but the remainder of the hormones were not detected. The developed method is sensitive, efficient, reliable and applicable to real samples.

Optimization of a pre-MEKC separation SPE procedure for steroid molecules in human urine samples

Many steroid hormones can be considered as potential biomarkers and their determination in body fluids can create opportunities for the rapid diagnosis of many diseases and disorders of the human body. Most existing methods for the determination of steroids are usually time- and labor-consuming and quite costly. Therefore, the aim of analytical laboratories is to develop a new, relatively low-cost and rapid implementation methodology for their determination in biological samples. Due to the fact that there is little literature data on concentrations of steroid hormones in urine samples, we have made attempts at the electrophoretic determination of these compounds. For this purpose, an extraction procedure for the optimized separation and simultaneous determination of seven steroid hormones in urine samples has been investigated. The isolation of analytes from biological samples was performed by liquid-liquid extraction (LLE) with dichloromethane and compared to solid phase extraction (SPE) with C18 and hydrophilic-lipophilic balance (HLB) columns. To separate all the analytes a micellar electrokinetic capillary chromatography (MECK) technique was employed. For full separation of all the analytes a running buffer (pH 9.2), composed of 10 mM sodium tetraborate decahydrate (borax), 50 mM sodium dodecyl sulfate (SDS), and 10% methanol was selected. The methodology developed in this work for the determination of steroid hormones meets all the requirements of analytical methods. The applicability of the method has been confirmed for the analysis of urine samples collected from volunteers--both men and women (students, amateur bodybuilders, using and not applying steroid doping). The data obtained during this work can be successfully used for further research on the determination of steroid hormones in urine samples.

Analysis of cortisol in hair--state of the art and future directions

Changes to long-term secretion of the glucocorticoid cortisol are considered to play a crucial role in mediating the link between chronic stress and the development of numerous immune system related diseases. However, obtaining valid assessments of long-term cortisol levels is difficult due to limitations of previous measurement strategies in blood, saliva or urine. This review discusses evidence on a recent methodological development assumed to provide a considerable advancement in this respect: the analysis of cortisol in hair. Being incorporated into the growing hair, hair cortisol concentrations (HCC) are assumed to provide a retrospective reflection of integrated cortisol secretion over periods of several months. Over the past years, supportive evidence has accumulated regarding several fundamental characteristics of HCC, including its validity as an index of long-term systemic cortisol levels, its reliability across repeated assessments and its relative robustness to a range of potential confounding influences. Based on this groundwork, research has now also commenced to utilise HCC for answering more specific questions regarding the role of long-term cortisol secretion in different stress and health-related conditions. The possibility of extending hair analysis to also capture long-term secretion of other steroid hormones (e.g., androgens or estrogens) provides a further intriguing prospect for future research. Given its unique characteristics, the use of hair analysis holds great promise to significantly enhance current understanding on the role of steroid hormones in psychoimmunological research.

Micellar electrokinetic chromatography for the determination of cortisol in urine samples in view of biomedical studies

An MEKC method used for the determination of cortisol in urine was developed and elaborated. In turn, the measurements of urinary free cortisol provided the diagnostic information for excess adrenal production of cortisol. MEKC realized by the addition of anionic surfactant SDS to the buffer solution was demonstrated to be the appropriate mode for the separation of cortisol and dexamethasone was used as internal standard. A buffer solution composed of 10 mM sodium tetraborate and 50 mM SDS at pH 8.8 was used. The MEKC assay was evaluated by analyzing a series of urine samples containing cortisol in variable concentrations. The proposed method was validated for specificity, linearity, LODs and LOQs, precision and trueness. The LOQ for cortisol equaled 5 ng/mL. The method was selective and reliable for identification and can detect changes of endogenous levels of cortisol in urine under different stress situations.

Micro determination of cortisol and cortisone in umbilical cord blood by chemiluminescent high-performance liquid chromatography

A simple, sensitive and specific chemiluminescent high-performance liquid chromatography method, based on the luminol reaction, for determination of serum cortisol and cortisone, was established. In infants, placental 11beta-hydroxysteroid dehydrogenase type 2 enzyme (11beta-HSD2) activity may affect adrenal function early after birth. The cortisol-cortisone ratio of serum concentrations in umbilical cord blood is an indicator of placental 11beta-HSD2 activity. The optimum conditions for the luminol reaction were determined to be 1.5 mM luminol, 0.6 M sodium hydroxide, 0.15 mm potassium hexacyanoferrate(III) and 200 mM potassium hexacyanoferrate (II). The calibration curves for cortisol and cortisone exhibited good linearity. The correlation coefficients of the calibration curves were 0.996. The intra- and inter-day precisions were in the ranges: cortisol 7.0-12.2 and 4.4-9.2%, cortisone 5.3-7.0 and 6.2-9.9%. The recoveries of these steroids were in the ranges: cortisol 97-105%, cortisone 94-102%. The limits of detection were as follows: cortisol, 0.17 microg/dl; cortisone 0.15 microg/dl. This assay could be successfully applied to determination of the cortisol-cortiosone ratio of serum concentrations in umbilical cord bloods.

Glycyrrhetinic acid attenuates vascular smooth muscle vasodilatory function in healthy humans

Abnormal glucocorticoid metabolism contributes to vascular dysfunction and cardiovascular disease. Cortisol activation of vascular mineralocorticoid and glucocorticoid receptors is regulated by two types of 11β-HSD (11-β hydroxysteroid dehydrogenase), namely 11β-HSD2 and 11β-HSD1 (type 2 and type 1 11β-HSD respectively). We hypothesized that inhibition of 11β-HSD would attenuate vascular function in healthy humans. A total of 15 healthy subjects were treated with the selective 11β-HSD inhibitor GA (glycyrrhetinic acid) or matching placebo in a randomized double-blinded cross-over trial. 11β-HSD activity was assessed by the urinary cortisol/cortisone ratio, and vascular function was measured using strain-gauge plethysmography. Endothelial function was measured through incremental brachial artery administration of methacholine (0.3–10 μg/min) and vascular smooth muscle function with incremental verapamil (10–300 μg/min). GA increased the 24-h urinary cortisol/cortisone ratio compared with placebo (P=0.008). GA tended to reduce the FBF (forearm blood flow) response to methacholine (P=0.09) and significantly reduced the FBF response to verapamil compared with placebo (P=0.04). MAP (mean arterial pressure) did not differ between the study conditions. 11β-HSD inhibition attenuated vascular smooth muscle vasodilatory function in healthy humans. Disturbances in cortisol activity resulting from 11β-HSD inactivation is therefore a second plausible mechanism for mineralocorticoid-mediated hypertension in humans.