Recent developments and future perspectives of microfluidics and smart technologies in wearable devices

Wearable devices are gaining popularity in the fields of health monitoring, diagnosis, and drug delivery. Recent advances in wearable technology have enabled real-time analysis of biofluids such as sweat, interstitial fluid, tears, saliva, wound fluid, and urine. The integration of microfluidics and emerging smart technologies, such as artificial intelligence (AI), machine learning (ML), and Internet of Things (IoT), into wearable devices offers great potential for accurate and non-invasive monitoring and diagnosis. This paper provides an overview of current trends and developments in microfluidics and smart technologies in wearable devices for analyzing body fluids. The paper discusses common microfluidic technologies in wearable devices and the challenges associated with analyzing each type of biofluid. The paper emphasizes the importance of combining smart technologies with microfluidics in wearable devices, and how they can aid diagnosis and therapy. Finally, the paper covers recent applications, trends, and future developments in the context of intelligent microfluidic wearable devices.

Deep eutectic solvent extraction of cortisol and cortisone from human saliva followed by LC-UV analysis

A novel extraction method was developed for the determination of cortisol and cortisone. In this study, we prepared a hydrophobic deep eutectic solvent (DES) by mixing trioctylmethylammonium chloride and pentafluorophenol as a hydrogen bond acceptor and a hydrogen bond donor, respectively, for use as the extraction solvent. The extraction of cortisol and cortisone was performed by adding a small volume of the DES to the aqueous sample. After centrifugation, the resulting sedimented DES phase was injected into a reversed-phase liquid chroamtography column, and the analytes were detected with an ultraviolet detector at 254 nm. Under the optimized extraction conditions, the enrichment factors of cortisol and cortisone were 9.3 and 8.5, respectively. Furthermore, the linear dynamic ranges were established over a concentration range of 10-200 pmol mL^-1 (r² > 0.9992), and the limits of detection of cortisol and cortisone were found to be 2.1 and 1.8 pmol mL^-1, respectively. The applicability of this method was evaluated by analyzing the cortisol and cortisone contents of human saliva samples.

Hair glucocorticoids and resting-state frontal lobe oxygenation: Findings from The Irish Longitudinal Study on Ageing

Cerebral blood flow and oxygenation are crucial for maintaining healthy brain structure and function, with hypoperfusion and hypometabolism associated with neurodegenerative and neuropsychiatric conditions. Chronic stress and elevated cortisol have also been associated with cognitive decline, poor mental health and peripheral vascular and cerebrovascular changes. It is plausible that glucocorticoids could alter brain structure and function through increased vulnerability to hypoperfusion and reduced oxygenation. The aim of the current study was to investigate the association between hair glucocorticoids (GCs) and frontal lobe oxygenation using near-infra red spectroscopy (NIRS) in a population sample of 1078 older adults. Data from Wave 3 of The Irish Longitudinal Study of Ageing was analysed. Hair samples were taken for the analysis of glucocorticoids and NIRS was used to measure frontal lobe oxygenation. After both minimal and full adjustment for covariates, hair cortisol and the cortisol-to-cortisone ratio were associated with lower Tissue Saturation Index (TSI; cortisol: B = -0.37, CI -0.60 to -0.14, p = .002; ratio: B = -0.43, CI -0.70 to -0.16, p = .002). Cortisone was not significantly associated with TSI (B = -0.17, CI -0.55 to.21, p = .388). The finding of an inverse relationship between frontal lobe oxygenation and GCs as assessed over a period of months may indicate that reduced oxygenation is one pathway through which chronically elevated GCs affect brain health and function. However, no causality can be inferred from the current data and prospective studies are required to interrogate this.

Understanding performance of 3D-printed sorbent in study of metabolic stability

Metabolic stability tests are one of the fundamental steps at the preclinical stages of new drug development. Microsomes, used as a typical enzymatic model of liver biotransformation, can be a challenging matrix for analytical scientists due to a high concentration of cellular proteins and membrane lipids. In the work, we propose a new procedure integrating biotransformation reaction with SPME-like protocol for sample clean-up. It is beneficial to increase the overall quality of results in contrary to the typical protein precipitation approach. A set of ten arylpiperazine analogs, six of which are considered promising drug candidates (and four are accepted drugs) were used as a probe to assess the goodness of the newly proposed approach. In order to promote an efficient extraction protocol, a new, miniaturized shape of a sorbent, suitable to perform the extraction in 100 µL of the sample has been designed. Termination of the biotransformation process by protein denaturation with hot water was additionally evaluated. A quantitative structure-property relationship (QSPR) study using Orthogonal Partial Least Squares (OPLS) technique to reveal insights to the sorption mechanism was also performed. The obtained results showed the new 3D-printed sorbent can be an attractive basis for the new sample preparation approach for metabolic stability studies and an alternative for commercially available protocols based on solid-phase microextraction (SPME) or solid-phase extraction (SPE) principles.

Antidepressant-like effects of pharmacological inhibition of FAAH activity in socially isolated female rats

Pharmacological inhibition of the enzyme fatty acid amide hydrolase (FAAH), which terminates signaling of the endocannabinoid N-arachidonoylethanolamine (or anandamide, AEA), exerts favourable effects in rodent models of stress-related depression. Yet although depression seems to be more common among women than men and in spite of some evidence of sex differences in treatment efficacy, preclinical development of FAAH inhibitors for the pharmacotherapy of stress-related depression has been predominantly conducted in male animals. Here, adult female rats were exposed to six weeks of social isolation and, starting from the second week, treated with the FAAH inhibitor URB694 (0.3 mg/kg/day, i.p.) or vehicle. Compared to pair-housed females, socially isolated female rats treated with vehicle developed behavioral (mild anhedonia, passive stress coping) and physiological (reduced body weight gain, elevated plasma corticosterone levels) alterations. Moreover, prolonged social isolation provoked a reduction in brain-derived neurotrophic factor (BDNF) and AEA levels within the hippocampus. Together, these changes are indicative of an increased risk of developing a depressive-like state. Conversely, pharmacological inhibition of FAAH activity with URB694 restored both AEA and BDNF levels within the hippocampus of socially isolated rats and prevented the development of behavioral and physiological alterations. These results suggest a potential interplay between AEA-mediated signaling and hippocampal BDNF in the pathogenesis of depression-relevant behaviors and physiological alterations and antidepressant action of FAAH inhibition in socially isolated female rats.

The 24-hour urinary cortisol in post-traumatic stress disorder: A meta-analysis

Objective

Previous studies found inconsistent results on the relationship between post-traumatic stress disorder (PTSD) and concentrations of 24-hour (24-h) urinary cortisol. This study performed a systematic review and meta-analysis to summarize previous findings on this relationship.

Methods

We searched in the databases of Web of Science, PubMed, Embase, and Psyc-ARTICLES for articles published before September 2018. We used the random-effects model with restricted maximum-likelihood estimator to synthesize the effect sizes by calculating the standardized mean difference (SMD) and assessing its significance.

Results

Six hundred and nineteen articles were identified from the preceding databases and 20 of them were included in the meta-analysis. Lower concentrations of 24-h urinary cortisol were observed in patients with PTSD when compared with the controls (SMD = -0.49, 95%CI [-0.91; -0.07], p = 0.02). Subgroup analysis revealed that the concentrations of 24-h urinary cortisol were lower in PTSD patients than in the controls for studies that included female participants or studies that included participants from the United States of America.

Conclusions

Overall, decreased levels of 24-h urinary cortisol were linked with the pathophysiology of PTSD. Nonetheless, more studies should be conducted to validate the molecular underpinnings of urine cortisol degeneration in PTSD.

Factors mediating the impacts of child abuse and intimate partner violence on chronic pain: a cross-sectional study

BACKGROUND

Most research on the health impacts of intimate partner violence (IPV) and child abuse has been conducted in Western countries and may not be generalizable to women living in different contexts, such as Saudi Arabia. Chronic pain, a disabling health issue associated with experiences of both child abuse and IPV among women, negatively impacts women's well-being, quality of life, and level of functioning. Yet, the psychosocial mechanisms that explain how abuse relates to chronic pain are poorly understood. We developed and tested a theoretical model that explains how both IPV and child abuse are related to chronic pain.

METHODS

We recruited a convenience sample of 299 Saudi women, who had experienced IPV in the past 12 months, from nine primary health care centers in Saudi Arabia between June and August 2015. Women completed a structured interview comprised of self-report measures of IPV, child abuse, PTSD, depressive symptoms, chronic pain, and social support. Using Structural equation modeling (SEM), we analyzed the proposed model twice with different mental health indicators as mediators: PTSD symptoms (Model 1) and depressive symptoms (Model 2).

RESULTS

Both models were found to fit the data, accounting for 31.6% (Model 1) and 32.4% (Model 2) of the variance in chronic pain severity. In both models, mental health problems (PTSD and depressive symptoms) fully mediated the relationship between severity of IPV and child abuse and chronic pain severity. Perceived family support partially mediated the relationship between abuse severity and depressive symptoms.

CONCLUSIONS

These results underscore the significance of considering lifetime abuse, women's mental health (depressive and PTSD symptoms) and their social resources in chronic pain management and treatment.

Social stress contagion in rats: Behavioural, autonomic and neuroendocrine correlates

The negative emotional consequences associated with life stress exposure in an individual can affect the emotional state of social partners. In this study, we describe an experimental rat model of social stress contagion and its effects on social behaviour and cardiac autonomic and neuroendocrine functions. Adult male Wistar rats were pair-housed and one animal (designated as "demonstrator" (DEM)) was submitted to either social defeat stress (STR) by an aggressive male Wild-type rat in a separate room or just exposed to an unfamiliar empty cage (control condition, CTR), once a day for 4 consecutive days. We evaluated the influence of cohabitation with a STR DEM on behavioural, cardiac autonomic and neuroendocrine outcomes in the cagemate (defined "observer" (OBS)). After repeated social stress, STR DEM rats showed clear signs of social avoidance when tested in a new social context compared to CTR DEM rats. Interestingly, also their cagemate STR OBSs showed higher levels of social avoidance compared to CTR OBSs. Moreover, STR OBS rats exhibited a higher heart rate and a larger shift of cardiac autonomic balance toward sympathetic prevalence (as indexed by heart rate variability analysis) immediately after the first reunification with their STR DEMs, compared to the control condition. This heightened cardiac autonomic responsiveness habituated over time. Finally, STR OBSs showed elevated plasma corticosterone levels at the end of the experimental protocol compared to CTR OBSs. These findings demonstrate that cohabitation with a DEM rat, which has experienced repeated social defeat stress, substantially disrupts social behaviour and induces short-lasting cardiac autonomic activation and hypothalamic-pituitary-adrenal axis hyperactivity in the OBS rat, thus suggesting emotional state-matching between the OBS and the DEM rats. We conclude that this rodent model may be further exploited for investigating the neurobiological bases of negative affective sharing between social partners under chronic social stress conditions.

Antidepressant-like activity and cardioprotective effects of fatty acid amide hydrolase inhibitor URB694 in socially stressed Wistar Kyoto rats

In humans, depression is often triggered by prolonged exposure to psychosocial stressors and is often associated with cardiovascular comorbidity. Mounting evidence suggests a role for endocannabinoid signaling in the regulation of both emotional behavior and cardiovascular function. Here, we examined cardiac activity in a rodent model of social stress-induced depression and investigated whether pharmacological inhibition of the enzyme fatty acid amide hydrolase (FAAH), which terminates signaling of the endocannabinoid anandamide, exerts antidepressant-like and cardioprotective effects. Male Wistar Kyoto rats were exposed to five weeks of repeated social stress or control procedure. Starting from the third week, they received daily administration of the selective FAAH inhibitor URB694 (0.1 mg/kg, i.p.) or vehicle. Cardiac electrical activity was recorded by radiotelemetry. Repeated social stress triggered biological and behavioral changes that mirror symptoms of human depression, such as (i) reductions in body weight gain and sucrose solution preference, (ii) hyperactivity of the hypothalamic-pituitary-adrenocortical axis, and (iii) increased immobility in the forced swim test. Moreover, stressed rats showed (i) alterations in heart rate daily rhythm and cardiac autonomic neural regulation, (ii) a larger incidence of spontaneous arrhythmias, and (iii) signs of cardiac hypertrophy. Daily treatment with URB694 (i) increased central and peripheral anandamide levels, (ii) corrected stress-induced alterations of biological and behavioral parameters, and (iii) protected the heart against the adverse effects of social stress. Repeated social stress in Wistar Kyoto rats reproduces aspects of human depression/cardiovascular comorbidity. Pharmacological enhancement of anandamide signaling might be a promising strategy for the treatment of these comorbid conditions.

Hair cortisone level is associated with PTSD׳s dysphoric arousal symptoms in highly traumatized Chinese females

BACKGROUND

Cortisone has been proposed as a useful additional biomarker for stress research. However, only very limited studies has investigated alterations of cortisone levels in stress-related mental disorder such as PTSD. The present study investigated the associations between PTSD symptomatology and hair cortisone levels which can reflect cumulative cortisone secretion over prolonged periods of time and is more robust to the influence of situational confounding.

METHODS

Participants included 201 females who experienced 2008 Wenchuan earthquake and lost their children during the disaster. PTSD symptoms were assessed with the PTSD Checklist (PCL), and depression symptoms with the Center for epidemiological studies depression scale (CES-D). Hair cortisone levels were quantified by liquid chromatography tandem mass spectrometer.

RESULTS

The results indicated that although hair cortisone secretion could not distinguish traumatized individuals with and without PTSD, it was uniquely linked to dysphoric arousal symptoms, a key aspect of the complex PTSD phenotype

LIMITATIONS

A sample of females exposed to specific traumatic events was used, and PTSD was assessed using a self-reported measure.

CONCLUSIONS

The findings provide preliminary evidence supporting the critical role of long-term cortisone changes in the development and maintenance of PTSD symptoms, and add to extant knowledge on the neuroendocrinological underpinnings of posttraumatic psychopathology.

Experience, cortisol reactivity, and the coordination of emotional responses to skydiving

Physiological habituation to laboratory stressors has previously been demonstrated, although the literature remains equivocal. Previous studies have found skydiving to be a salient naturalistic stressor that elicits a robust subjective and physiological stress response. However, it is uncertain whether (or how) stress reactivity habituates to this stressor given that skydiving remains a risky, life-threatening challenge with every jump despite experience. While multiple components of the stress response have been documented, it is unclear whether an individual’s subjective emotions are related to their physiological responses. Documenting coordinated responsivity would lend insight into shared underlying mechanisms for the nature of habituation of both subjective (emotion) and objective (cortisol) stress responses. Therefore, we examined subjective emotion and cortisol responses in first-time compared to experienced skydivers in a predominantly male sample (total n = 44; males = 32, females = 12). Hierarchical linear modeling (HLM) revealed that experienced skydivers showed less reactivity and faster recovery compared to first-time skydivers. Subjective emotions were coordinated with physiological responses primarily within first-time skydivers. Pre-jump anxiety predicted cortisol reactivity within first-time, but not experienced, skydivers. Higher post-jump happiness predicted faster cortisol recovery after jumping although this effect overlapped somewhat with the effect of experience. Results suggest that experience may modulate the coordination of emotional response with cortisol reactivity to skydiving. Prior experience does not appear to extinguish the stress response but rather alters the individual’s engagement of the HPA axis.

24 h urinary free cortisol in large-scale epidemiological studies: short-term and long-term stability and sources of variability

BACKGROUND

Function of the hypothalamus-pituitary-adrenal (HPA) axis has been associated with several somatic and psychiatric health problems. The amount of free cortisol excreted in the urine during 24h (24-h UFC) has often been used as a proxy for HPA-axis function. Reference values for 24-h UFC and their stability in the short and long term, as well as sources of variability, are largely lacking.

METHODS

This study was performed in a general population cohort. Participants collected 24-h UFC on two consecutive days (T1), and repeated this collection approximately 2 years later (T2). Cortisol in urine was measured using LC-MS/MS. Height and weight were measured at the research facilities; glomerular filtration rate was estimated using creatinine clearance. Psychological distress (General Health Questionnaire), smoking, alcohol use and exercise were measured by means of questionnaires.

RESULTS

24-h UFC stability on a day-to-day basis was 0.69 (T1, N=1192) and 0.72 (T2, N=963) (both p<0.001). Long-term stability as indicated by correlation between 2-day averages of T1 and T2 was 0.60 (N=972, p<0.001). Multivariable linear regression analysis revealed that 24-h UFC was predicted by urine volume (standardized beta 0.282 (T1, N=1556) and 0.276 (T2, N=1244); both p<0.001) and glomerular filtration rate (standardized beta 0.137 (T1) and 0.179 (T2); both p<0.001), while also sex explained a small part (standardized beta for female sex -0.057 (T1) and -0.080 (T2); both p<0.05).

CONCLUSION

24-h UFC is moderately stable both in the short and the long term. The effects of urine volume and glomerular filtration rate on 24-h UFC are much stronger than those of sex.

Multi-matrix assay of cortisol, cortisone and corticosterone using a combined MEPS-HPLC procedure

The development and validation of a bioanalytical assay for the simultaneous determination of cortisol, cortisone and corticosterone levels in several matrices, such as saliva, plasma, blood and urine samples have been described. The method is based on a rapid test which combines a microextraction by packed sorbent procedure and liquid chromatography-diode array technique. Chromatographic separation of the analytes (cortisol, cortisone and corticosterone) and the internal standard (methylprednisolone) was achieved in less than 10min on a reversed-phase pentafluorophenyl column using a mobile phase composed of phosphate buffer and acetonitrile. The assay was performed after an innovative microextraction procedure by means of C8 sorbent which guaranteed good clean-up of the matrices and satisfactory extraction yield of the analytes. Moreover, the method gave linear results over a range of 5-100ngmL(-1) and showed good selectivity and precision. This method was successfully applied for quantifying corticosteroids in specific matrices derived from some healthy volunteers in comparison to two socially diversified groups, namely former heroin addicts undergoing opioid replacement therapy and poly-drug abusers.

Chemometric evaluation of urinary steroid hormone levels as potential biomarkers of neuroendocrine tumors

Neuroendocrine tumors (NETs) are uncommon tumors which can secrete specific hormone products such as peptides, biogenic amines and hormones. So far, the diagnosis of NETs has been difficult because most NET markers are not specific for a given tumor and none of the NET markers can be used to fulfil the criteria of high specificity and high sensitivity for the screening procedure. However, by combining the measurements of different NET markers, they become highly sensitive and specific diagnostic tests. The aim of the work was to identify whether urinary steroid hormones can be identified as potential new biomarkers of NETs, which could be used as prognostic and clinical course monitoring factors. Thus, a rapid and sensitive reversed-phase high-performance liquid chromatographic method (RP-HPLC) with UV detection has been developed for the determination of cortisol, cortisone, corticosterone, testosterone, epitestosterone and progesterone in human urine. The method has been validated for accuracy, precision, selectivity, linearity, recovery and stability. The limits of detection and quantification were 0.5 and 1 ng mL⁻¹ for each steroid hormone, respectively. Linearity was confirmed within a range of 1–300 ng mL⁻¹ with a correlation coefficient greater than 0.9995 for all analytes. The described method was successfully applied for the quantification of six endogenous steroid levels in human urine. Studies were performed on 20 healthy volunteers and 19 patients with NETs. Next, for better understanding of tumor biology in NETs and for checking whether steroid hormones can be used as potential biomarkers of NETs, a chemometric analysis of urinary steroid hormone levels in both data sets was performed.

Cross-sectional relationship between chronic stress and mineral concentrations in hair of elementary school girls

Chronic stress exposure is associated with diverse negative health outcomes. It has been hypothesised that stress may also negatively affect the body's mineral status. This study investigates the association between chronic stress and long-term mineral concentrations of calcium (Ca), copper (Cu), iron (Fe), magnesium (Mg), phosphorus (P) and zinc (Zn) in scalp hair among elementary school girls. Complete information on child-reported stress estimates (Coddington Life Events Scale (CLES)), hair cortisone and hair mineral concentrations, and predefined confounders in the stress-mineral relationship (i.e. age, body mass index, physical activity, diet, hair colour and parental education) was provided cross-sectionally for 140 girls (5-10 years old). The relationship between childhood stress measures (predictor) and hair minerals (outcome) was studied using linear regression analysis, adjusted for the abovementioned confounders. Hair cortisone concentrations were inversely associated with hair mineral concentrations of Ca, Mg, Zn and the Ca/P ratio. Children at risk by life events (CLES) presented an elevated Ca/Mg ratio. These findings were persistent after adjustment for confounders. This study demonstrated an independent association between chronic stress measures and hair mineral levels in young girls, indicating the importance of physiological stress-mineral pathways independently from individual or behavioural factors. Findings need to be confirmed in a more heterogeneous population and on longitudinal basis. The precise mechanisms by which stress alters hair mineral levels should be further elucidated.

Cortisone in hair of elementary school girls and its relationship with childhood stress

Children may be exposed to stressful situations with adverse effects on their physiological and psychological health. As cortisone may be a useful additional biomarker for stress research and as it has been shown to be detectable in human hair, this study measured physiological concentrations of hair cortisone in 223 elementary school girls and explored its relationship with child-reported estimates of stress, more specifically questionnaires on major life events (i.e., Coddington Life Events Scale for Children), emotions (i.e., anger, anxiety, sadness, and happiness), and coping strategies (i.e., emotion- versus problem-focused coping). Cortisone concentrations were positively correlated with the overall life event score for the past 6 months (rho = 0.223, p = 0.004), as well as with the negative event score for this period (rho = 0.227, p = 0.003; N = 165). Cortisone did not correlate with emotions or coping styles reported by the children.

CONCLUSION

Despite its exploratory nature, this study may suggest elevated hair cortisone concentrations under psychosocial stress in young children. Although the observed findings should be interpreted with prudence, this study may encourage further research elucidating the potential importance and relevance of hair cortisone analysis as an additional or substituting stress biomarker for hair cortisol.

Ultra performance liquid chromatography-tandem mass spectrometry method for profiling of steroid metabolome in human tissue

In humans, steroids play a broad and vital role in regulation of gene expression, secondary sexual characteristics, maturation, reproduction, cardiovascular health, neurological functions, etc., but imbalance in steroid metabolism is also linked to development and progression of many diseases, such as cancer, neurodegenerative diseases, and cardiovascular diseases. Hence, measurement of steroids in biological samples is essential to monitor human health. Currently, there is radioimmunoassay, gas chromatography-mass spectrometry (GC/MS), and liquid chromatography-mass spectrometry (LC-MS) methods developed for steroid measurements in biological samples. However, these methods require elaborate sample preparation procedures and have concerns(s) related to reproducibility, dynamic range, time, costs, and most importantly the total coverage of steroids. Also currently, there is no method available for comprehensive steroid profiling in a single LC-MS run that includes androgens, corticosteroids, progestogens, estrogens, estrogen metabolites, estrogen conjugates, and estrogen-DNA adducts as well as exogenous steroid derivatives. Here, I present a global steroid metabolic profiling method based on liquid-liquid extraction (LLE) followed by ultra performance liquid chromatography (UPLC)-tandem mass spectrometry (MS/MS) for simultaneous measurement of over 100 indigenous as well as exogenous steroids in about 12 min, without derivatization. The method was successfully applied to determine steroid hormone levels in the breast tissue of healthy women. Overall presence of all major classes of steroids as well as estrogen derivatives was detected in breast tissue.

Steroid profiles as potential biomarkers in patients with urogenital tract cancer for diagnostic investigations analyzed by liquid chromatography coupled to mass spectrometry

Large discrepancy remains for the hormone-responsible cancers with regards to the conditions generating the optimal opportunity for cancerogenesis. In the research, altered steroid profiles were observed in patients with urogenital tract cancer diseases, namely bladder, kidney, prostate and testis ones. The presented steroid profiles from 154 subjects, including 77 urogenital tract cancer patient and 77 healthy controls were determined by liquid chromatography coupled to mass spectrometry method. Because the original experimental data obtained as a result of analytical experiment in order to interpret them in better way required the appropriate pre-treatment, the data were standardized by scaling and centering. In order to determine which samples form a collection for a high-capacity predictive model, Kennard-Stone's algorithm was used. A principal component analysis of preprocessed data provided better consistency of the steroid profiles with health status of subjects than PCA profiles without data preprocessing and showed a tendency to separate clusters of cancer patients from healthy subjects. The discriminant analysis was also performed and the percent of correct classification of cancer patients and control group was calculated. Finally, detailed studies examined the role of steroid profiles measured in urine, and considered as potential biomarkers related to urogenital cancer and associated renal dysfunctions.

The comparison of two column classification systems during the chromatographic analysis of steroids

Nowadays, due to the availability of hundreds of brands of reversed-phase liquid chromatographic columns, the selection of suitable columns can be difficult. Therefore, a good characterization and classification system is very important. Among published papers, the classification system based on quantitative structure-retention relationships and a method developed at the Katholieke Universiteit Leuven also exist. In quantitative structure-retention relationships, retention is evaluated in terms of the chemical structure of the analytes and the physicochemical properties of both the stationary and mobile phase. The second system allows to rank columns due to the values of four parameters and the calculation of specific F(KUL)-values for a reference column and to be compared with others. In this paper, the classification systems based both on quantitative structure-retention relationships and the F(KUL)-values using principal components analysis were compared. Moreover, the proposed column ranking systems have been checked in clinical practice case considering liquid chromatography determination of six steroid hormones in urine samples. Despite that the matching of both methods is not exactly the same, both classification systems provide simple, reliable and comparable results.