Treatment of acute decompensation of maple syrup urine disease in adult patients with a new parenteral amino-acid mixture.

BACKGROUND: Acute decompensation of maple syrup urine disease (MSUD) is usually treated by enteral feeding with an amino-acid mixture without leucine (Leu), valine or isoleucine. However, its administration is ineffective in cases of gastric intolerance and some adult patients refuse enteral feeding via a nasogastric tube. We developed a new parenteral amino-acid mixture for patients with MSUD. METHODS: Seventeen decompensation episodes in four adult patients with MSUD treated with a parenteral amino-acid mixture (group P) were compared to 18 previous episodes in the same patients treated by enteral feeding (group E). RESULTS: The mean Leu concentration at presentation was similar in the groups P and E (1196.9 µmol/L and 1212.2 µmol/L, respectively). The mean decrease in the Leu concentration during the first 3 days of hospitalisation was significantly higher in group P than group E (p = 0.0026); there were no side effects. The mean duration of hospitalisation was similar (4 vs. 4.5 days, p = NS). No patient in group P deteriorated whereas one patient in group E required dialysis. CONCLUSION: This new parenteral amino-acid mixture is safe and allows efficient Leu concentration decrease during acute MSUD decompensation episodes in adults. Its use avoids the need for nasogastric tube insertion.

[Clinical case of the month. Idiopathic mediastinal fibrosis]. / Fibrose médiastinale idiopathique.

Fibrosing mediastinitis is a rare condition characterized by an excessive growth of dense fibrous tissue within the mediastinum. The etiology of the disease is most often a fungal infection and may in some cases be idiopathic. We present the case of a patient with chronic obstructive pulmonary disease (COPD) suffering from fibrosing mediastinitis of undetermined origin and in whom the diagnosis was established by histopathological analysis after mediastinoscopy.

Interstitial fibrosis evolution on early sequential screening renal allograft biopsies using quantitative image analysis.

Screening renal biopsies (RB) may assess early changes of interstitial fibrosis (IF) after transplantation. The aim of this study was to quantify IF by automatic color image analysis on sequential RB. We analyzed RB performed at day (D) 0, month (M) 3 and M12 from 140 renal transplant recipients with a program of color segmentation imaging. The mean IF score was 19 ± 9% at D0, 27 ± 11% at M3 and 32 ± 11% at M12 with a 8% progression during the first 3 months and 5% between M3 and M12. IF at M3 was correlated with estimated glomerular rate (eGFR) at M3, 12 and 24 (p < 0.02) and IF at M12 with eGFR at M12 and 48 (p < 0.05). Furthermore, IF evolution between D0 and M3 (ΔIFM3-D0) was correlated with eGFR at M24, 36 and 48 (p < 0.03). IF at M12 was significantly associated with male donor gender and tacrolimus dose (p = 0.03). ΔIFM3-D0 was significantly associated with male donor gender, acute rejection episodes (p = 0.04) and diabetes mellitus (p = 0.02). Thus, significant IF is already present before transplantation. IF evolution is more important during the first 3 months and has some predictive ability for change in GFR. Intervention to decrease IF should be applied early, i.e. before 3 months, after transplantation.

[Application of nonaqueous capillary electrophoresis for chiral pharmaceutical and biomedical analysis ]. / Applications de l'électrophorèse capillaire en milieu non aqueux en analyse chirale pharmaceutique et biomedicale.

The potentialities of nonaqueous capillary electrophoresis for chiral analysis were demonstrated through many pharmaceutical and biomedical applications, such as the stereoselective assay of acidic and basic drugs in plasma and urine as well as in vitro metabolism studies. A fundamental aspect of the quality control of chiral drugs in single-isomer forms, i.e. the enantiomeric purity determination, was also investigated. Moreover, the mechanisms of intermolecular interactions involved in the chiral separations observed in nonaqueous systems were elucidated using nuclear magnetic resonance.

Interstitial fibrosis quantification in renal transplant recipients randomized to continue cyclosporine or convert to sirolimus.

Conversion from cyclosporine (CsA) to sirolimus at week 12 after kidney transplantation is associated with a significant improvement in renal function. The aim of this analysis was to investigate the effect of this conversion on interstitial fibrosis (IF), a hallmark of chronic allograft injury, in patients taking part in the CONCEPT trial. This multicenter, prospective, trial included 193 renal recipients randomized at week 12 to switch from CsA to sirolimus or to continue CsA, with mycophenolate mofetil. Routine biopsy with automated, quantified assessment of IF by a program of color segmentation was performed at 1 year in 121 patients. At 1 year, renal function was significantly improved in the conversion group as assessed by estimated GFR (MDRD) and measured GFR. Biopsy results, however, showed no between-group difference in percentage of IF. Calculated GFR at 1 year was significantly associated with the percentage of IF (p = 0.004, R(2)= 0.07). By multivariate analysis diabetic patients had more fibrosis than non-diabetic patients. In conclusion, although kidney transplant patients converted from CsA to sirolimus showed significant improvement in renal function, we found no difference of IF on 1-year biopsies.

Insulin aggregation assessment by capillary gel electrophoresis without sodium dodecyl sulfate: Comparison with size-exclusion chromatography.

Size-exclusion chromatography (SEC) is a method of choice for the analysis of protein aggregates in pharmaceuticals. The United States and European Pharmacopoeias currently use a SEC method with an acidic pH mobile phase to assess the content of aggregates in insulin formulations. In this article, we analyzed aggregated human insulin samples and demonstrated that both methods under neutral conditions, namely neutral pH SEC (nSEC) and capillary gel electrophoresis (CGE), yield to similar aggregate content contrary to SEC under acidic conditions (aSEC). aSEC showed polymeric complexes that were not observed in nSEC and CGE. During method development, the effect on SEC profiles of arginine and acetonitrile were highlighted. In CGE, the effect of SDS on disruption of non-covalent insulin aggregates was confirmed and the benefit of sodium deoxycholate addition in sieving gel was discussed. The three methods were applied to the analysis of an insulin formulation and similar results to those obtained for human insulin as raw material were observed. Finally, the CGE method was used to study the stability of human insulin under different storage conditions. In view of the obtained results one may question the relevance of the current pharmacopoeia method to study insulin aggregates by emphasizing the importance of the mobile phase composition and pH in SEC. The new CGE method developed is an easy method for studying non-covalent aggregates of insulin, which could be applied to other proteins.

Validation of a nonaqueous capillary electrophoretic method for the enantiomeric purity determination of R-flurbiprofen using a single-isomer amino cyclodextrin derivative.

Nonaqueous capillary electrophoresis (NACE) was successfully applied to the enantiomeric purity determination of R-flurbiprofen using 6-monodeoxy-6-mono(2-hydroxy)propylamino-beta-cyclodextrin (IPA-beta-CD) as chiral selector. The nonaqueous BGE was made up of 20 mM IPA-beta-CD, 20 mM ammonium camphorsulfonate and 40 mM ammonium acetate in methanol. Flufenamic acid was selected as internal standard. The CE method was carefully optimized in order to prevent the adsorption of the cationic CD onto the capillary wall, and therefore, to avoid loss of peak efficiency and enantioresolution. To achieve this goal, the addition of ammonium camphorsulfonate was found to be necessary. In the selected conditions, the determination of 0.1% of S-flurbiprofen in R-flurbiprofen could be performed using the method of standard additions. The NACE method was then fully validated by applying a novel strategy using accuracy profiles.

Hepatitis C Continuum of Care in a Treatment Center in Sub-Saharan Africa.

BACKGROUND: Hepatitis C virus (HCV) infection is a major public health challenge in Cameroon with over three million people infected. Government efforts to improve care and treatment are unsatisfactory and need to be assessed. We aimed at studying the several steps along the HCV continuum of care in one of two hepatitis treatment centers in Cameroon. METHODS: We undertook a retrospective chart review of anti-HCV positive individuals, who attended the Douala general hospital between 2008 and 2015. We defined the HCV treatment cascade as follows: step 1-HCV RNA testing, step 2-complete pre-therapeutic evaluation (genotyping and liver fibrosis markers), step 3-initiation of treatment, step 4-treatment completion, and step 5-sustained virological response (SRV). Each successive step in the HCV care continuum was dependent on passing through the previous step. RESULTS: The mean age of the 669 anti-HCV antibody positive individuals was 57 (sd: ±13) years. Females were 52.8% of the study population. 410 (61.3%) were tested for HCV RNA. Three hundred and sixty-six (54.7%) were confirmed to have viral replication (HCV RNA positive). One hundred and eighty (26.9%) did a complete pre-therapeutic evaluation (both HCV genotyping and liver fibrosis assessment included). Eighty-one (12.1%) initiated treatment with pegylated interferon/ribavirin. Seventy-two (10.8%) completed treatment and 44 (6.6%) had SVR. Sociodemographic characteristics including age, gender, marital status, having medical insurance, and profession were associated with attaining later steps in the care cascade. CONCLUSION: This study shows that HCV continuum of care and treatment is less optimal at the Douala general hospital and is highly impacted by socio-economic factors. Continued efforts are needed to improve HCV care.

Robustness testing of a chiral NACE method for R-timolol determination in S-timolol maleate and uncertainty assessment from quantitative data.

A robustness test of a capillary electrophoresis method for the chiral separation of timolol in nonaqueous acidified media was performed. A two-level Plackett-Burman design was applied in which one qualitative and six quantitative factors were examined. Resolution, migration times and relative migration times to pyridoxine (selected as internal standard) were examined as qualitative responses to evaluate electrophoretic performance. A quantitative response, the content of R-timolol in S-timolol maleate sample, was also considered. Even though some significant factor effects were observed on the qualitative responses, it was still possible to quantify the R-timolol in the S-timolol maleate samples properly. The quantitative response was not significantly affected by the selected factors, demonstrating the robustness of the procedure. However, the use of different HDMS-beta-CD batches seemed to affect both types of responses necessitating to introduce a warning in the procedure. Since the experiments of the Plackett-Burman design can be assimilated to laboratories in an interlaboratory study, uncertainty can be evaluated using the robustness test data. The robustness test was set-up in such a way that the required variances could be estimated.

Quantification of interstitial fibrosis by image analysis on routine renal biopsy 1 year after transplantation in patients managed by C2 monitoring of cyclosporine microemulsion.

BACKGROUND: Renal interstitial fibrosis (IF), the main histopathologic feature of chronic allograft nephropathy (CAN), may be an important surrogate endpoint for patient follow-up. IF is currently assessed by semiquantitative analysis, but automatic color image analysis may be a more reliable, reproducible method to evaluate IF. We performed a retrospective analysis to calculate IF on routine renal biopsies 1 year after transplantation. METHODS: Data were obtained from MO2ART, a prospective multicenter trial in which the cyclosporine microemulsion dose was adjusted based on C(2) levels. We included 26 patients in whom routine renal biopsy at 1 year was available from two centers. For each biopsy, a section was analyzed by a program of color segmentation image that automatically extracted green-colored areas characteristic of IF. Results were expressed as percent IF and grade namely grade I, <25%; grade II, 25% to 50%; and grade III, >50%. The results were compared according to clinical and biological data. RESULTS: The 26 patients had a mean IF score of 0.35 +/- 0.04. We observed 34.6% CAN grade I; 46.1%, grade II; and 19.2%, grade III. Serum creatinine at 3 years was greater in the higher grade of automated IF by repeated ANOVA. CONCLUSION: Automatic quantification of IF on routine biopsy at 1 year after transplantation was predictive of renal outcome. This technique may provide an interesting tool for the early diagnosis of CAN after renal transplantation.

Partial filling affinity capillary electrophoresis as a useful tool for fragment-based drug discovery: A proof of concept on thrombin.

With the emergence of more challenging targets, a relatively new approach, fragment-based drug discovery (FBDD), proved its efficacy and gained increasing importance in the pharmaceutical industry. FBDD identifies low molecular-weight (MW) ligands (fragments) that bind to biologically important macromolecules, then a structure-guided fragment growing or merging approach is performed, contributing to the quality of the lead. However, to select the appropriate fragment to be evolved, sensitive analytical screening methods must be used to measure the affinity in the µM or even mM range. In this particular context, we developed a robust and selective partial filling affinity CE (ACE) method for the direct binding screening of a small fragment library in order to identify new thrombin inhibitors. To demonstrate the accuracy of our assay, the complex dissociation constants of three known thrombin inhibitors, namely benzamidine, p-aminobenzamidine and nafamostat were determined and found to be in good concordance with the previously reported values. Finally, the screening of a small library was performed and demonstrated the high discriminatory power of our method towards weak binders compared to classical spectrophotometric activity assay, proving the interest of our method in the context of FBDD.

Prevalence and Characteristics of Hepatitis Delta Virus Infection in a Tertiary Hospital Setting in Cameroon.

BACKGROUND/AIMS: Hepatitis B virus (HBV) and hepatitis D virus (HDV) coinfection is associated with more severe liver disease than HBV alone. More knowledge on the epidemiology and clinical impact of HDV-infected individuals is needed in Cameroon.We aimed at determining the frequency of anti-HDV antibody testing in hepatitis B surface antigen (HBsAg) positive patients, the proportion of anti-HDV positivity, and the characteristics of anti-HDV positive compared to anti-HDV negative patients in a tertiary hospital setting in Cameroon. METHODS: A cross-sectional study was conducted. Clinical records of chronic HBV-infected patients attending the gastroenterology unit at the Douala General Hospital from 2010 to 2014 were reviewed. RESULTS: Of 365 files of HBsAg-positive patients defined as chronic HBV infection, 80.5% (294) were tested for anti-HDV antibodies, among whom 10.5% (31/294) were positive. Median aspartate aminotransferase (P < 0.0001), alanine aminotransferase (P < 0.0001), and gamma glutaryl transpeptidase (P < 0.0001) were significantly higher while platelets count (P < 0.002) and prothrombin time (P < 0.0001) were significantly lower in anti-HDV positive compared to anti-HDV negative patients. Liver necroinflammation (P < 0.0001), fibrosis score (P < 0.0001), and decompensated cirrhosis (P < 0.0001) were also significantly associated with anti-HDV positivity. CONCLUSION: The proportion of anti-HDV antibody positivity remains high in this setting and was significantly associated with more severe liver disease compared to those who were anti-HDV negative. More studies are needed to evaluate rates of HDV testing in other centers in Cameroon and the subregion. Preventive strategies for HBV prevention, which also apply to HDV, must still be reinforced by healthcare providers and policy makers.

[Drug-induced renal calculi]. / Lithiases médicamenteuses.

Drug-induced renal calculi represent 1-2% of all renal calculi. They include two categories: those resulting from the urinary crystallisation of a highly excreted, poorly soluble drug or metabolite, and those due to the metabolic effects of a drug. Indinavir, used in HIV-infected patients, sulfonamides, especially sulfadiazine, and triamterene, which is less prescribed today, are the most frequent. Besides these drugs, about twenty other molecules, among them silicate-containing drugs and some antibiotics have been reported in patients receiving high doses or long-term treatments. Calculi analysis by physical methods such as infrared spectroscopy or x-ray diffraction can demonstrate the presence of the drug or its metabolites inside the calculi. In those calculi due to the metabolic effects of a drug, diagnosis relies on both stone analysis and clinical inquiry. Incidence of such calculi is probably underestimated, especially those due to calcium/vitamin D supplements or carbonic anhydrase inhibitors. Drug-induced calculi occur more often during high-dose or long term treatments, but there are also patient-related risk factors in relation to urine pH, urine output and other parameters, which can provide a basis for preventive treatment of such calculi. A better knowledge of these lithogenic complications of treatments and of solubility characteristics of drugs should reduce the incidence of drug-induced nephrolithiasis, especially in patients with identified risk factors.

Enantioselective capillary electrophoresis-mass spectrometry of amino acids in cerebrospinal fluid using a chiral derivatizing agent and volatile surfactant.

The sensitivity of coupled enantioselective capillary electrophoresis-mass spectrometry (CE-MS) of amino acids (AAs) is often hampered by the chiral selectors in the background electrolyte (BGE). A new method is presented in which the use of a chiral selector is circumvented by employing (+)-1-(9-fluorenyl)ethyl chloroformate (FLEC) as chiral AA derivatizing agent and ammonium perfluorooctanoate (APFO) as a volatile pseudostationary phase for separation of the formed diastereomers. Efficient AA derivatization with FLEC was completed within 10 min. Infusion experiments showed that the APFO concentration hardly affects the MS response of FLEC-AAs and presents significantly less ion suppression than equal concentrations of ammonium acetate. The effect of the pH and APFO concentration of the BGE and the capillary temperature were studied in order to achieve optimized enantioseparation. Optimization of CE-MS parameters, such as sheath-liquid composition and flow rate, ESI and MS settings was performed in order to prevent analyte fragmentation and achieve sensitive detection. Selective detection and quantification of 14 chiral proteinogenic AAs was achieved with chiral resolution between 1.2 and 8.6, and limits of detection ranging from 130 to 630 nM injected concentration. Aspartic acid and glutamic acid were detected, but not enantioseparated. The optimized method was applied to the analysis of chiral AAs in cerebrospinal fluid (CSF). Good linearity (R(2) > 0.99) and acceptable peak area and electrophoretic mobility repeatability (RSDs below 21% and 2.4%, respectively) were achieved for the chiral proteinogenic AAs, with sensitivity and chiral resolution mostly similar to obtained for standard solutions. Next to l-AAs, endogenous levels of d-serine and d-glutamine could be measured in CSF revealing enantiomeric ratios of 4.8%-8.0% and 0.34%-0.74%, respectively, and indicating the method's potential for the analysis of low concentrations of d-AAs in presence of abundant l-AAs.

[Significance of the urine strip test in case of stunted growth]. / Intérêt de l'examen des urines à la bandelette en cas de retard de croissance.

Observation of stunted growth in children usually leads the general practitioner to refer the patient to endocrinologists or gastroenterologists. In most cases, after a complementary check-up, the diagnosis is made and treatment is initiated. However, certain cases remain undiagnosed, particularly renal etiologies, such as proximal tubulopathy. The urine strip test at the initial check-up would be an easy and inexpensive test to avoid delayed diagnosis. The aim of the present paper is to increase general physicians' and pediatricians' awareness of the significance of questioning the parents and using the urine strip test for any child presenting stunted growth. We report a patient case of a 20-month-old child admitted to the emergency department for severe dehydration. He had displayed stunted growth since the age of 5 months and showed a negative etiologic check-up at 9 months of age. Clinical examination at admission confirmed stunted growth with loss of 2 standard deviations and signs of dehydration with persistent diuresis. Skin paleness, ash-blond hair, and signs of rickets were also observed and the urine strip test showed positive pads for glycosuria and proteinuria. Polyuria and polydipsia were also revealed following parents' questioning, suggesting proximal tubulopathy (Fanconi syndrome). Association of stunted growth, rickets, polyuria and polydipsia, glycosuria (without ketonuria and normal glycemia), and proteinuria suggest nephropathic cystinosis. Ophthalmic examination showed cystine deposits in the cornea. The semiotic diagnosis of nephropathic cystinosis was confirmed by leukocyte cystine concentrations and genetic investigations. This case report clearly illustrates the significance of the urine strip test to easily and quickly concentrate the diagnosis of stunted growth on a renal etiology (glycosuria, proteinuria), especially on proximal tubulopathy for which the most frequent cause is nephropathic cystinosis. Specificity of nephropathic cystinosis treatment is that the age of treatment initiation is crucial and determinant for the prognosis of the disease and the onset of final stage renal failure. Therefore, the urine strip test should be included in the systematic check-up of stunted growth to identify any renal etiology.

Cardiac troponin-I on diagnosis predicts early death and refractoriness in acquired thrombotic thrombocytopenic purpura. Experience of the French Thrombotic Microangiopathies Reference Center.

BACKGROUND: Cardiac involvement is a major cause of mortality in patients with thrombotic thrombocytopenic purpura (TTP). However, diagnosis remains underestimated and delayed, owing to subclinical injuries. Cardiac troponin-I measurement (cTnI) on admission could improve the early diagnosis of cardiac involvement and have prognostic value. OBJECTIVES: To assess the predictive value of cTnI in patients with TTP for death or refractoriness. PATIENTS/METHODS: The study involved a prospective cohort of adult TTP patients with acquired severe ADAMTS-13 deficiency (< 10%) and included in the registry of the French Reference Center for Thrombotic Microangiopathies. Centralized cTnI measurements were performed on frozen serum on admission. RESULTS: Between January 2003 and December 2011, 133 patients with TTP (mean age, 48 ± 17 years) had available cTnI measurements on admission. Thirty-two patients (24%) had clinical and/or electrocardiogram features. Nineteen (14.3%) had cardiac symptoms, mainly congestive heart failure and myocardial infarction. Electrocardiogram changes, mainly repolarization disorders, were present in 13 cases. An increased cTnI level (> 0.1 µg L(-1) ) was present in 78 patients (59%), of whom 46 (59%) had no clinical cardiac involvement. The main outcomes were death (25%) and refractoriness (17%). Age (P = 0.02) and cTnI level (P = 0.002) showed the greatest impact on survival. A cTnI level of > 0.25 µg L(-1) was the only independent factor in predicting death (odds ratio [OR] 2.87; 95% confidence interval [CI] 1.13-7.22; P = 0.024) and/or refractoriness (OR 3.03; 95% CI 1.27-7.3; P = 0.01). CONCLUSIONS: A CTnI level of > 0.25 µg L(-1) at presentation in patients with TTP appears to be an independent factor associated with a three-fold increase in the risk of death or refractoriness. Therefore, cTnI level should be considered as a prognostic indicator in patients diagnosed with TTP.

Separation, identification and quantitation of ceramides in human cancer cells by liquid chromatography-electrospray ionization tandem mass spectrometry.

Ceramides are important intracellular second messengers that play a role in the regulation of cell growth, differentiation and programmed cell death. Qualitative and quantitative analysis of these second messengers requires sensitive and specific analytical methods to detect endogenous levels of individual ceramide species and to differentiate between them. Nine synthetic ceramides were separated by liquid chromatography coupled to tandem mass spectrometry on a C18 bonded silica column. The lipids were eluted in gradient elution mode using a mixture of water, acetonitrile and 2-propanol as mobile phase. They were detected by reaction monitoring performed on positive ion electrospray generated ions. Collision-induced fragmentations conducted on ceramides produced a well characteristic product ion at m/z 264, making multiple reaction monitoring (MRM) well suited for various ceramides quantitative measurements. After optimization of the extraction step, the proposed methodology was able to identify and quantify different ceramide species issued from human cancer cells. The method could be validated for C16, C18 and C20 ceramides, quantified at the nanogram level. The validation exhibits good results with respect to linearity, accuracy and precision.

[Pheochromocytoma: 25 years of experience. Report of 199 cases]. / Phéochromocytomes: 25 ans d'expérience. A propos de 199 cas.

The methods for diagnosing pheochromocytoma have progressed in 25 years, so changing the clinical, biological and tumoral presentations. The authors compare the features of 199 patients with pheochromocytoma operated between 1975 and 2001 by quartiles. The frequency and known duration of hypertension, plasma adrenaline, the tumour size and proportion of cases which were malignant from the outset, have decreased over the observation period (p < 0.01). The average age and proportion of familial cases or associated with diabetes or those of asymptomatic patients (with incidentaloma), has not changed significantly. The pheochromocytoma were adrenal (104 right, 60 left, 12 bilateral) or ectopic (23) and 13 were malignant from the outset. Over a median 5 year follow-up, 35 pheochromocytomas recurred either in the benign or malignant forms. Recurrences of tumours of the right adrenal were more common than those of the left adrenal gland (p = 0.03). In conclusion, pheochromocytomas are diagnosed earlier, at a stage when the tumours are smaller and less secreting. The higher incidence and recurrence rate of right adrenal pheochromocytoma remain unexplained.

[Clinical case of the month. Von Hippel-Lindau disease]. / Le cas clinique du mois. Maladie de Von Hippel-Lindau.

VHL disease is a rare genetical disease with a poor long-term prognosis. Clinical features include retineous angiomas, CNS hemangioblastomas, pheochromocytomas and renal cysts. Renal cysts are bilateral and frequently lead to malignant transformation. Surgical treatment of renal cysts is preferably delayed until a minimum of 3 cm diameter has been reached. Treatment has to be as conservative as possible, knowing that uni- or bilateral nephrectomy often has to be carried out later.

Influence of sample and mobile phase composition on peptide retention behaviour and sensitivity in reversed-phase liquid chromatography/mass spectrometry.

Because the chromatographic behaviour of peptides is totally different from that of small molecules, a good understanding of the mechanisms that occur from injection to detection in reversed-phase LC-MS is strongly recommended to successfully develop not only qualitative but also quantitative methods. In this study, design of experiments was used in order to investigate the influence of the experimental parameters, i.e. sample and mobile phase composition, on a peptide mixture covering a wide range of molecular weights, isoelectric points and hydropathies. First, a screening design was developed to identify the significant factors concerning mobile phase (ion-pairing reagent nature and concentration) and sample composition (organic modifier proportion and ion-pairing reagent nature) on retention and response intensity (sensitivity). Then, after having selected the experimental domain and the significant factors, a full factorial design was used to further investigate the role of the considered factors and their interactions. Interestingly, ion-pairing reagent nature present in the sample had a tremendous effect on retention and response intensity. Optimal conditions leading to good sensitivity and adequate peptide retention without band splitting were selected and could be used as starting point for rapid method development using classical solvents and ion-pairing reagents.