Molecular testing of chronic myeloid leukaemia in low resource areas.

Most cancer cases occur in areas of low resources. The diagnosis, treatment and monitoring of cancers is especially challenging in these locations. Unique partnerships exist between non-profit organisations and pharmaceutical companies to provide free drugs to CML patients throughout the world if the diagnosis can be rigorously and unambiguously established. But there lies the rub: How do you perform molecular diagnostics in areas where even electricity is unreliable? Here we describe the evolution of testing patients from low resource areas, which, when merged with a remarkable effort to bring tyrosine kinase inhibitors to patients across the globe, have led to survival outcomes similar to cases in industrialised countries.

Sensitive Detection of SARS-CoV-2-Specific Antibodies in Dried Blood Spot Samples.

Dried blood spot (DBS) samples can be used for the detection of severe acute respiratory syndrome coronavirus 2 spike antibodies. DBS sampling is comparable to matched serum samples with a relative 98.1% sensitivity and 100% specificity. Thus, DBS sampling offers an alternative for population-wide serologic testing in the coronavirus pandemic.

Implementation of an Affordable Method for MPS Diagnosis from Urine Screening to Enzymatic Confirmation: Results of a Pilot Study in Morocco.

BACKGROUND: Rapid and accurate diagnosis of mucopolysaccharidoses (MPS) is still a challenge due to poor access to screening and diagnostic methods and to their extensive clinical heterogeneity. The aim of this work is to perform laboratory biochemical testing for confirming the diagnosis of mucopolysaccharidosis (MPS) for the first time in Morocco. METHODS: Over a period of twelve months, 88 patients suspected of having Mucopolysaccharidosis (MPS) were referred to our laboratory. Quantitative and qualitative urine glycosaminoglycan (GAG) analyses were performed, and enzyme activity was assayed on dried blood spots (DBS) using fluorogenic substrates. Enzyme activity was measured as normal, low, or undetectable. RESULTS: Of the 88 patients studied, 26 were confirmed to have MPS; 19 MPS I (Hurler syndrome; OMIM #607014/Hurler-Scheie syndrome; OMIM #607015), 2 MPS II (Hunter syndrome; OMIM #309900), 2 MPS IIIA (Sanfilippo syndrome; OMIM #252900), 1 MPS IIIB (Sanfilippo syndrome; OMIM #252920) and 2 MPS VI (Maroteaux-Lamy syndrome; OMIM #253200). Parental consanguinity was present in 80.76% of cases. Qualitative urinary glycosaminoglycan (uGAGs) assays showed abnormal profiles in 31 cases, and further quantitative urinary GAG evaluation and Thin Layer Chromatography (TLC) provided important additional information about the likely MPS diagnosis. The final diagnosis was confirmed by specific enzyme activity analysis in the DBS samples. CONCLUSIONS: The present study shows that the adoption of combined urinary substrate analysis and enzyme assays using dried blood spots can facilitate such diagnosis, offer an important tool for an appropriate supporting care, and a specific therapy, when available.

The testing of people with any risk factor for hepatitis C in community pharmacies is cost-effective.

New antiviral drugs with high efficacy mean the hepatitis C virus (HCV) can now be eliminated. To achieve this, it is necessary to identify undiagnosed cases of HCV. However, the costs of testing should be considered when judging the overall cost-effectiveness of treatment. This study describes the cost-effectiveness of a community pharmacy testing service in a population of people at risk of HCV living on the Isle of Wight (United Kingdom). Dry blood spot testing was conducted in anyone with a known risk factor for HCV in 20 community pharmacies. The outcomes and costs were entered into a Markov model. Cost and health utilities from the model were used to calculate an incremental cost-effectiveness ratio (ICER). In 24 months, 186 tests were conducted, 13 were positive for HCV RNA and six of these (46%) received treatment during the follow-up period. All achieved a sustained virological response at 3 months. The overall cost of the testing and treatment intervention was £242 183, and the ICER for the service was £3689 per quality-adjusted life year (QALY) gained. If screening had been restricted to just people with a history of injecting drug use (PWID) the ICER would have been £4865 per QALY gained. The service was effective at identifying people with HCV infection, and despite the additional cost of targeted testing, its cost-effectiveness was below the commonly accepted thresholds. In this setting, restricting targeted testing to PWID would not improve the cost-effectiveness.

Model-based cost-effectiveness estimates of testing strategies for diagnosing hepatitis C virus infection in people who use injecting drugs in Senegal.

BACKGROUND: Scaling-up the access to hepatitis C virus (HCV) diagnostics for people who use injecting drugs (PWID) is essential to reduce the HCV incidence in low and middle-income countries. METHODS: A decision tree model was developed to compare the cost-effectiveness of 12 strategies for diagnosing HCV in Senegal with a health sector perspective. Strategies included HCV-Ab screening and confirmation of viraemia (based on HCV-RNA or HCV core antigen detection) or only the latter step. Laboratory assays and decentralized tools (point-of-care (POC) tests and dried blood spot (DBS) samples) were included. The base-case assumed a 38.9% seroprevalence, as reported in the PWID population of Dakar. RESULTS: Compared to the cheapest strategy (POC HCV-Ab followed by POC HCV-RNA (S5)), one strategy remained un-dominated in the base-case: POC HCV-Ab followed by venepuncture-based laboratory HCV-RNA (S3). Above a lost to follow-up testing rate of 2.3%, combining POC HCV-Ab with HCV-RNA on DBS (S4) became more cost-effective than S3. Above this threshold, a single-step POC HCV-RNA (S12) was also found un-dominated (ICER to S5=€3,297.50). S5, S12 and S4 cost €14.21, €17.03 and €36.55/screened individual. Incremental cost-effectiveness ratios (€/additional true positive case) were 2,164.82 (S12 versus S5) and 3,297.50 (S4 versus S12). Whenever HCV seroprevalence reached 55.5%, S12 became more cost-effective than S5. Moreover, S4 required a budget 2 to 2.5 times higher than S5 or S12 for diagnosing 90% of HCV-infected PWID in Dakar. CONCLUSION: A two-step POC-based strategy (S5) would be the most cost-effective option among those proposed in this study for diagnosing HCV in PWID in Senegal. This study illustrates how the lack of secure financing and of data on PWID in LMICs, render difficult to identify the most sustainable strategy in those countries, as well as its implementation.

Prenatal diagnosis of genetic diseases directly using paper-dried cord blood as the starting material for PCR.

A rapid and low-cost method of diagnosis is becoming important for detecting fetal inherited diseases, including single-gene disorders and chromosomal abnormalities. Here, we demonstrated an innovation that use paper-dried cord blood (PCB) as the starting material for PCR and whole genome amplification without any DNA extraction step at a very low cost. A novel PCR buffer named "DDB buffer" containing ammonium sulfate and glycerol were used instead of the conventional 10× PCR buffer. The amplicons were directly analyzed through microchip electrophoresis and whole genome sequencing. Inhibitory substances in filter paper were effectively inactivated using DDB buffer. Direct PCR amplification of DNA fragments ranging from 100 to 900 bp using filter paper spotted with 0.5 to 5 µL of cord blood and various anticoagulants was successful. We were able to determine fetal single-gene disorders and chromosomal diseases in all 46 chromosomes using PCB samples successfully. Compared with prenatal diagnosis using purified DNA, the proposed method is simple, fast, less prone to cross-contamination at minimal cost. Researchers and clinical and healthcare workers may employ this method for genetic diagnosis using cord blood samples with minimum laboratory resources. This method is very promising for a variety of genetic diagnosis applications in underserved communities at the point of need in developing areas. Graphical abstract.

Clinical and economic aspects of newborn screening for severe combined immunodeficiency: DEPISTREC study results.

PURPOSE: Severe combined immunodeficiency (SCID) refers to a group of genetic disorders characterized by greatly compromised cellular and humoral immunity. Children with SCID are asymptomatic at birth, but they die from infections within the first months of life if not treated. Quantification of T-cell receptor excision circles is an extremely sensitive screening method for detecting newborns who may have SCID.The goal of the DEPISTREC study was to evaluate the feasibility of nationwide newborn screening for severe T-cell lymphopenia in France as well as its economic and clinical utility. METHODS: The test universally used for neonatal screening for SCID was the quantification of TRECs on Guthrie cards. We compared a group of 190,517 babies from 48 maternities across the country who underwent newborn SCID screening with a control group of 1.4 million babies out of whom 28 were diagnosed with SCID without such screening during the course of the study. RESULTS: Within the screening group, 62 babies were found to be lymphopenic, including three with SCID. The cost of screening ranged from 4.7€ to €8.15 per newborn. The average 18-month cost was €257,574 vs €204,697 in the control group. CONCLUSIONS: In this large-scale study, we demonstrate that routine SCID screening is feasible and effective. This screening offers the additional benefit of aiding in the diagnosis of non-SCID lymphopenia. Economic evaluation allowed us to calculate the cost per test. Newborn screening may also prevent death by SCID before any curative treatment can be administered. The difference in cost between screened and control children could not be ascertained because of the very low numbers and death of one of the children tested.

IP-10 dried blood spots assay monitoring treatment efficacy in extrapulmonary tuberculosis in a low-resource setting.

Treatment efficacy is difficult to evaluate in extrapulmonary tuberculosis (EPTB) patients. Interferon-γ inducible protein (IP-)10 has been suggested as a biomarker for response to treatment. We have investigated if IP-10 from dried plasma spots (DPS) or dried blood spots (DBS) can be used in treatment monitoring of EPTB patients in a low-resource setting of Zanzibar. IP-10 levels in plasma, DPS and DBS samples collected before, during (2 months) and after TB treatment of 36 EPTB patients (6 culture and/or Xpert MTB/RIF positive and 30 clinically diagnosed) and 8 pulmonary tuberculosis (PTB) patients, were quantified by an enzyme-linked immunosorbent assay. There was a high positive correlation between IP-10 measured in plasma and DPS and DBS, respectively. We found a significant decline in IP-10 levels from baseline to end of treatment in plasma, DPS and DBS, both in EPTB and PTB patients. The declines were observed already after 2 months in HIV negative patients. In conclusion, the DPS/DBS IP-10 assay allows for easy and manageable monitoring in low-resource settings and our findings suggest that IP-10 may serve as a biomarker for treatment efficacy in EPTB patients, albeit further studies in cohorts of patients with treatment failure and relapse are needed.

Increasing hepatitis C virus screening in people who inject drugs in Switzerland using rapid antibody saliva and dried blood spot testing: A cost-effectiveness analysis.

People who inject drugs (PWID) are a key high-risk group for Hepatitis C Virus (HCV) infection due to the sharing of needles and drug-preparation equipment. However, only approximately 50% of PWID are currently screened for HCV in Switzerland. At present, screening of PWID occurs in general practice via venepuncture. Compared to venepuncture, screening via rapid antibody saliva and dried blood spot (DBS) tests is well adapted to PWID, who typically have difficult venous access. The cost-effectiveness of an increased access screening programme of PWID (increased screening using rapid antibody saliva tests and DBS tests [semi-quantitative viraemia and viral genotype]) was analysed through a decision tree screening model combined with the outputs of a Markov treatment model. Sensitivity and scenario analyses examined the uncertainty of results. At a willingness to pay (WTP) threshold of CHF 100 000 (USD 105 000) per quality-adjusted life year (QALY), the increased access screening programme was cost-effective compared to current screening, with a base case incremental cost-effectiveness ratio of CHF 7 940 (USD 8337) per QALY. The net monetary benefit was CHF 959 802 668 (USD 1 007 792 801) for the PWID population and CHF 94 469 (USD 99 192) per person. The increased access screening programme had a 97.0% probability of being cost-effective compared to the current screening method at the WTP threshold of CHF 100 000 (USD 105 000). The results showed an increased access screening programme that uses tests which are better suited to the PWID population to be more cost-effective, due to the increased uptake that rapid antibody saliva and DBS tests generate.

Using dried blood spots to facilitate therapeutic drug monitoring of antiretroviral drugs in resource-poor regions.

Objectives: We evaluated whether dried blood spots (DBS) are suitable to monitor combined ART when samples are collected in rural Tanzania and transported over a long distance to a specialized bioanalytical laboratory. Methods: Plasma and DBS samples were collected in Tanzania from study patients treated with nevirapine, efavirenz or lopinavir. In addition, plasma, whole blood and DBS samples were obtained from a cohort of HIV patients at the site of the bioanalytical laboratory in Switzerland. DBS samples were analysed using a fully automated LC-MS/MS method. Results: Comparison of DBS versus plasma concentrations of samples obtained from the bridging study in Switzerland indicated an acceptable bias only for nevirapine (18.4%), whereas for efavirenz and lopinavir a pronounced difference of -47.4% and -48.1% was found, respectively. Adjusting the DBS concentrations by the haematocrit and the fraction of drug bound to plasma proteins removed this bias [efavirenz +9.4% (-6.9% to +25.7%), lopinavir +2.2% (-20.0% to +24.2%)]. Storage and transportation of samples from Tanzania to Switzerland did not affect the good agreement between plasma and DBS for nevirapine [-2.9% (-34.7% to +29.0%)] and efavirenz [-9.6% (-42.9% to +23.8%)]. For lopinavir, however, adjusted DBS concentrations remained considerably below [-32.8% (-70.4% to +4.8%)] corresponding plasma concentrations due to decay of lopinavir in DBS obtained under field conditions. Conclusions: Our field study shows that the DBS technique is a suitable tool for therapeutic drug monitoring in resource-poor regions; however, sample stability remains an issue for certain analytes and therefore needs special consideration.

Dried Blood Spots for Global Health Diagnostics and Surveillance: Opportunities and Challenges.

There is increasing interest in using dried blood spot (DBS) cards to extend the reach of global health and disease surveillance programs to hard-to-reach populations. Conceptually, DBS offers a cost-effective solution for multiple use cases by simplifying logistics for collecting, preserving, and transporting blood specimens in settings with minimal infrastructure. This review describes methods to determine both the reliability of DBS-based bioanalysis for a defined use case and the optimal conditions that minimize pre-analytical sources of data variability. Examples by the newborn screening, drug development, and global health communities are provided in this review of published literature. Sources of variability are linked in most cases, emphasizing the importance of field-to-laboratory standard operating procedures that are evidence based and consider both stability and efficiency of recovery for a specified analyte in defining the type of DBS card, accessories, handling procedures, and storage conditions. Also included in this review are reports where DBS was determined to not be feasible because of technology limitations or physiological properties of a targeted analyte.

Evaluation of a novel micro-sampling device, Mitra™, in comparison to dried blood spots, for analysis of praziquantel in Schistosoma haematobium-infected children in rural Côte d'Ivoire.

Pharmacokinetic (PK) studies with paediatric populations are increasing in importance for drug development. However, conventional PK sampling methods are characterised by invasiveness and low patient adherence, unsuitable for use with sensitive population, such as children. Mitra™ is a novel volumetric absorptive micro-sampling device, which offers an alternative to the dried blood spotting (DBS) technique, a current popular sampling technique within PK studies. We tested Mitra™ for the first time in the framework of a randomised controlled trial in rural Côte d'Ivoire. Thirty-five school-aged children, infected with Schistosoma haematobium, were sampled with both DBS and Mitra™, at 10 time points after treatment with praziquantel (PZQ). An extraction method for PZQ from Mitra™ was developed, optimised and validated. Analytes, namely R- and S-praziquantel (R-/SPZQ) and the main human metabolite, R-trans-4-OH-praziquantel, were measured using liquid chromatography-tandem mass spectrometry and the results were compared with Bland-Altman analysis to determine agreement between matrices. PK parameters, such as maximal plasma concentration and area under the concentration-time curve, were estimated using non-compartmental analysis. While we observed strong positive correlation (R2 > 0.98) and agreement between both matrices within the calibration line and quality control samples, Mitra™ revealed higher concentrations of all the analytes in the majority of patients' samples compared to DBS sampling, namely 63% samples for RPZQ, 49% for SPZQ and 78% for the metabolite were overestimated. While T1/2 and Tmax were in agreement between both matrices, area under the curve and maximal blood concentration were up to 2× higher for Mitra™ samples, with P < 0.005 for all parameters except Cmax of SPZQ, which was not significantly different between the two matrices. The reasons for the higher PZQ concentrations, more pronounced in incurred Mitra™ samples compared to spiked samples, are yet to be fully explored. Mitra™ appears superior to DBS in terms of simplicity and practicality however labelling issues and the high price of Mitra™ are difficult to overlook.

Early infant diagnosis of HIV-1 infection in Luanda, Angola, using a new DNA PCR assay and dried blood spots.

BACKGROUND: Early diagnosis and treatment reduces HIV-1-related mortality, morbidity and size of viral reservoirs in infants infected perinatally. Commercial molecular tests enable the early diagnosis of infection in infants but the high cost and low sensitivity with dried blood spots (DBS) limit their use in sub-Saharan Africa. OBJECTIVES: To develop and validate a sensitive and cheap qualitative proviral DNA PCR-based assay for early infant diagnosis (EID) in HIV-1-exposed infants using DBS samples. STUDY DESIGN: Chelex-based method was used to extract DNA from DBS samples followed by a nested PCR assay using primers for the HIV-1 integrase gene. Limit of detection (LoD) was determined by Probit regression using limiting dilutions of newly produced recombinant plasmids with the integrase gene of all HIV-1 subtypes and ACH-2 cells. Clinical sensitivity and specificity were evaluated on 100 HIV-1 infected adults; 5 infected infants; 50 healthy volunteers; 139 HIV-1-exposed infants of the Angolan Pediatric HIV Cohort (APEHC) with serology at 18 months of life. RESULTS: All subtypes and CRF02_AG were amplified with a LoD of 14 copies. HIV-1 infection in infants was detected at month 1 of life. Sensitivity rate in adults varied with viral load, while diagnostic specificity was 100%. The percentage of HIV-1 MTCT cases between January 2012 and October 2014 was 2.2%. The cost per test was 8-10 USD which is 2- to 4-fold lower in comparison to commercial assays. CONCLUSIONS: The new PCR assay enables early and accurate EID. The simplicity and low-cost of the assay make it suitable for generalized implementation in Angola and other resource-constrained countries.

Cost Evaluation of Dried Blood Spot Home Sampling as Compared to Conventional Sampling for Therapeutic Drug Monitoring in Children.

Dried blood spot (DBS) sampling for the purpose of therapeutic drug monitoring can be an attractive alternative for conventional blood sampling, especially in children. This study aimed to compare all costs involved in conventional sampling versus DBS home sampling in two pediatric populations: renal transplant patients and hemato-oncology patients. Total costs were computed from a societal perspective by adding up healthcare cost, patient related costs and costs related to loss of productivity of the caregiver. Switching to DBS home sampling was associated with a cost reduction of 43% for hemato-oncology patients (€277 to €158) and 61% for nephrology patients (€259 to €102) from a societal perspective (total costs) per blood draw. From a healthcare perspective, costs reduced with 7% for hemato-oncology patients and with 21% for nephrology patients. Total savings depend on the number of hospital visits that can be avoided by using home sampling instead of conventional sampling.

Development and validation of ultrafast LC-MS/MS method for quantification of anti-influenza agent camphecene in whole rat blood using dried blood spots and its application to pharmacokinetic studies.

A fast, selective and sensitive procedure for quantitation of the camphor-based anti-influenza agent camphecene in whole rat blood was developed and validated using dried blood spots and LC-MS/MS. The method was validated according to recommendations of the FDA and EMA in terms of selectivity, linearity, accuracy, precision, recovery, matrix factor, stability, and carry-over. Sample preparation included spotting 20µL of whole blood taken from the tail vein onto the paper, drying and extracting the analyte, followed by evaporation of the solvent and analysis of the residue. HPLC separations were run on a reversed-phase microcolumn; the time of analysis was less than 2min. MS/MS detection was performed on a triple quadrupole mass-spectrometer using multiple reaction monitoring (MRM) mode. Transitions 196.4→122.2/153.3 and 152.2→93.1/107.2 were monitored for camphecene and 2-adamantylamine hydrochloride (internal standard), respectively. The intra- and inter-day precisions and accuracies, matrix factor, carry-over and recovery were within acceptable limits. Despite low extraction recovery (less than 2%), the sensitivity of the method was enough to detect the analyte in the concentration range 50-2500ng/mL. The application of the method was shown in pharmacokinetic studies of camphecene in rats at a dose of 10mg/kg.

Simplified Paper Format for Detecting HIV Drug Resistance in Clinical Specimens by Oligonucleotide Ligation.

Human immunodeficiency virus (HIV) is a chronic infection that can be managed by antiretroviral treatment (ART). However, periods of suboptimal viral suppression during lifelong ART can select for HIV drug resistant (DR) variants. Transmission of drug resistant virus can lessen or abrogate ART efficacy. Therefore, testing of individuals for drug resistance prior to initiation of treatment is recommended to ensure effective ART. Sensitive and inexpensive HIV genotyping methods are needed in low-resource settings where most HIV infections occur. The oligonucleotide ligation assay (OLA) is a sensitive point mutation assay for detection of drug resistance mutations in HIV pol. The current OLA involves four main steps from sample to analysis: (1) lysis and/or nucleic acid extraction, (2) amplification of HIV RNA or DNA, (3) ligation of oligonucleotide probes designed to detect single nucleotide mutations that confer HIV drug resistance, and (4) analysis via oligonucleotide surface capture, denaturation, and detection (CDD). The relative complexity of these steps has limited its adoption in resource-limited laboratories. Here we describe a simplification of the 2.5-hour plate-format CDD to a 45-minute paper-format CDD that eliminates the need for a plate reader. Analysis of mutations at four HIV-1 DR codons (K103N, Y181C, M184V, and G190A) in 26 blood specimens showed a strong correlation of the ratios of mutant signal to total signal between the paper CDD and the plate CDD. The assay described makes the OLA easier to perform in low resource laboratories.

Development and Validation of a New Low-Cost Enzyme-Linked Immunoassay for Serum and Dried Blood Spot Thyroglobulin.

BACKGROUND: Thyroglobulin (Tg), a biomarker of iodine nutrition, can be measured on dried blood spots (DBS), which simplifies collection and transport in surveys. The World Health Organization recommends DBS-Tg for monitoring iodine status in children. It could also be a useful iodine biomarker during pregnancy. However, the Tg antibody (Ab) used in earlier DBS-Tg assays is no longer commercially available. The aims of the present study were: (i) to develop a new low-cost serum and DBS-Tg sandwich enzyme-linked immunosorbent assay for assessment of Tg in population studies; (ii) to check the stability of DBS-Tg during long-term storage; and (iii) to assess within-subject variability in DBS-Tg. METHODS: Serum and DBS samples were measured from healthy pregnant women (n = 424) with the new assays, as well as the Immulite 2000 (Siemens), including TgAb positive (n = 150) and TgAb negative (n = 274) women. DBS-Tg stability was tested over 15 weeks of storage at -20 °C. Within-subject variability was evaluated over four weeks in four healthy adults. RESULTS: Intra-assay and interassay variability was 4.4-7.3% and 10.1-12.9% for the new serum Tg assay, and 7.6-12.3% and 7.6-16.5% for the DBS-Tg assay. Correlation between the two serum methods was high (r = 0.68, p < 0.01). Assay performance in all women and those TgAb negative was comparable. Correlation between the new serum Tg assay and the DBS-Tg assay was high (r = 0.78, p < 0.01), and agreement expressed as a function of the average Tg concentration for the two methods (X) was 0.59X -4.59 µg/L. DBS-Tg was stable for 15 weeks stored at -20 °C. Within-subject variability in DBS-Tg was 21.1%. Reagents and antibodies costs for the new serum and DBS assays are ∼ US$1. CONCLUSIONS: These new low-cost serum and DBS-Tg assays perform well over a wide range of Tg concentrations, and the field-friendly DBS assay may be particularly useful in population studies of iodine nutrition.

[Sequencing babies?]. / Séquencer les bébés ? - Chroniques génomiques.

An extension of newborn screening to genome sequencing is now feasible but raises a number of scientific, organisational and ethical issues. This is being explored in discussions and in several funded trials, in order to maximize benefits and avoid some identified risks. As some companies are already offering such a service, this is quite an urgent matter.

Analysis of γ-hydroxy butyrate by combining capillary electrophoresis-indirect detection and wall dynamic coating: application to dried matrices.

γ-Hydroxybutyric acid (GHB) is a powerful central nervous system depressant, currently used in medicine for the treatment of narcolepsy and alcohol dependence. In recent years, it has gained popularity among illegal club drugs, mainly because of its euphoric effects as well as doping agent and date rape drug. The purpose of the present work was the development of a rapid analytical method for the analysis of GHB in innovative biological matrices, namely dried blood spots (DBSs) and dried urine spots (DUSs). The analytical method is based on capillary zone electrophoresis with indirect UV absorption detection at 210 nm and capillary wall dynamic coating. The background electrolyte is composed of a phosphate buffer containing nicotinic acid (probe for detection) and cetyltrimethylammonium bromide (CTAB, reversal of electroosmosis in wall dynamic coating). The influence of probe and CTAB concentration, together with buffer pH, on migration time and signal response was investigated. Under the optimized conditions, analytical linearity and precision were satisfactory; absolute recovery values were also high (>90 %); the use of dried matrices (DBSs and DUSs) was advantageous as an alternative matrix to classical ones. No interferences were found either from the most common exogenous or from endogenous compounds. This analytical approach can offer a rapid, precise and accurate method for GHB determination in innovative biological samples, which could be important for screening purposes in clinical and forensic toxicology. Graphical Abstract CE method, by combined indirect UV detection and dynamic coating, for GHB determination in DBSs and DUSs.