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Phase II metabolites play an important role in diazepam-related cases. The study aimed to assess the stability of diazepam's phase II metabolites in dried blood spots on filter paper. A piece of filter paper was spotted with 100 µL of whole blood (added 1% sodium fluoride as needed) obtained from participant who received 5 mg diazepam orally, air dried for 2 h at room temperature, and then stored at different conditions. Whole spots were cut at 0.1 cm from the outer edge of blood spots at post-consumption time-points of prior (zero), 5, 16, 35, 61, 120 days and 1, 1.5 years. Analytes were extracted with methanol/water mixture (8:2, v/v) and determined using HPLC-MS/MS. Decomposition rules were analyzed by a statistical software "SPSS". Temazepam glucuronide remained stable (0.5–18.6% loss) at 20 ℃ and at 20 ℃ with 1% sodium fluoride for 16 days, while it was unstable after 5 days at 4 ℃ (21.1–26.2% loss) and − 20 ℃ (28.9 - 34.4% loss). After 35 days, temazepam glucuronide concentrations began to fluctuate significantly under all conditions, and an obvious increase (290.4–355.1%) was observed in 1.5 years. Oxazepam glucuronide was always unstable after 5 days, the percentage loss was even 100% when it was stored for 61 days and 1.5 years. Dried blood spots on ordinary filter paper are recommended to be stored at 20 ℃ or 20 ℃ with 1% sodium fluoride within 16 days. Samples should be analyzed immediately or stored in sterile and dry media. • TG was stable on filter paper at 20 ℃ with or without 1 % NaF within 16 days, and it is a more reliable marker in real cases. • OG was always unstable after 5 days, the percentage loss was even 100% when it was stored for 61 days and 1.5 years. • DBS on filter paper in diazepam-related cases are recommended to be stored at 20 ℃ with or without 1 % NaF within 16 days. [ABSTRACT FROM AUTHOR]

A novel all-in-one paper-based sampling concept for mass spectrometric bottom-up protein analysis is here demonstrated in a chip format integrating instant immunocapture, protein reduction, - alkylation and tryptic digestion all in-device. Conventional laboratory grade filter paper was coated with the polymer 2-hydroxyethyl methacrylate-co-2-vinyl-4,4-dimethyl azlactone (pHEMA-VDM) with a subsequent covalent immobilization of the monoclonal antibody E27 targeting the biomarker human chorionic gonadotropin (hCG). In-device protein reduction and alkylation was optimized with regards to reagent concentration and reaction pH. The sampling concept showed a high degree of performance between 10 and 1000 ng/mL (R2 > 0.99) by a five-point calibration curve sampled with hCG spiked to human serum samples and freshly collected whole blood samples, respectively. LOD (experimentally obtained at 100 pg/mL (2.64 pM/0.9 IU/L)) was demonstrated to be up to ten times lower with more than six times faster sample preparation than what has previously been reported for on-paper analysis of hCG in human serum samples. Image 1 • All-in-one paper-based sampling concept in chip format for mass spectrometric bottom-up protein analysis. • A simple sampling concept for sensitive analysis of lower abundant proteins related to disease state protein applications. • Paper-based sampling chip integrated with mAb E27 and all steps necessary for analysis of proteins in biological matrices. • A high degree of performance sampled with human serum and freshly collected whole blood samples. • Demonstrated with the biomarker human chorionic gonadotropin. [ABSTRACT FROM AUTHOR]

This study set out to examine pre-analytical factors affecting the frequency of positive results in newborn screening for biotinidase deficiency. This investigation was prompted by an increase in the annual screen positive rate for biotinidase deficiency in Ontario from 2.65x10−4 in 2016 to 6.57x10−4 in 2017. Season and trend decomposition was used to separate seasonality from an underlying trend in the time series of biotindase activity measurements for the period 2014–01-12 to 2019–07-27 (n = 798,770). This analysis revealed a marked seasonal effect (winter = median + ⩽ 17 MRU, summer = mean - ⩽ 20 MRU) and a non-linear negative trend. Seasonal temperature was correlated with biotinidase results (Pearson's r = 0.79) but not with the observed negative trend (Pearson's r = 0.0025). Time series analysis of biotinidase results grouped by print lot of filter paper revealed that recently printed filter paper cards inhibit biotinidase and that this inhibition resolved over time. This study demonstrates that biotindase activity is inhibited by both increased seasonal temperature and collection on newly printed filter cards. [ABSTRACT FROM AUTHOR]

BACKGROUND: Gaucher disease (GD) is a lysosomal storage disorder characterized by a deficiency of the lysosomal acid β-D-glucosidase (GBA). The aim of this study was to develop an ultramicro-fluorometric assay based on the method of Chamoles et al. for determining GBA activity in dried blood spots on filter paper (DBS). METHODS: The assay used 3-mm diameter blood spot and 8 mmol/l of 4-methylumbelliferyl-β-D-glucoside as enzymatic substrate. The reaction occurred in plates incubated at 37°C for 20 hours and the enzyme activity was expressed in μmol hydrolysed substrate/l blood/h. The fluorescence of the enzyme product was automatically measured in a fluorometer-photometer reader (SUMA Technology). RESULTS: The intra and inter-assay coefficients of variation were lower than 9 and 12%, respectively, and the recovery range was 97-109%.Three patients with GD were correctly diagnosed using the ultramicroassay. Healthy newborn DBS samples (n = 3003) from the National Neonatal Screening Program were analyzed, and the mean GBA activity was 5.7 μmol/l blood/h. Our assay showed high Pearson (n = 26; r = 0.99) and concordance correlations (ρc = 0.99) with the traditional method described by Chamoles et al. CONCLUSIONS: The analytical performance characteristics of our ultramicro-fluorometric assay suggest that it can be used in the diagnosis of GD in newborns and adults. [ABSTRACT FROM AUTHOR]

• Remote dried blood spot (DBS) self-collection in older adults is highly feasible. • Remote DBS yields high-quality spots, sufficient for assaying multiple biomarkers, with high participant adherence. • Inflammatory markers (CRP, IL-6, TNF-α) from self-collected DBS are reliable and valid. Dried blood spots (DBS) provide a minimally invasive method to assess inflammatory markers and can be collected remotely at-home or in-person in the lab. However, there is a lack of methodological information comparing these different collection methods and in older adults. We investigated the feasibility (including adherence, yield, quality, and participant preferences) and measurement properties (reliability, validity) of remotely collected DBS inflammatory markers in older adults. Participants (N = 167, mean age = 72, range: 60–96 years) collected their own DBS (finger prick on filter paper) during three remote interviews over ∼ 6 months. Within 4–5 days on average of their last remote interview, a subset of 41 participants also attended an in-person lab visit that included a researcher-collected DBS sample, venous blood draw, and survey to assess participant preferences of DBS collection. DBS and venous blood were assayed for CRP, IL-6, and TNF-α. Adherence: 98% of expected DBS samples (493 out of 501) were completed and mailed back to the lab. Yield: 97% of DBS samples were sufficient for all assays. Quality: On average, 0.80 fewer optimal spots (60uL of blood that filled the entire circle) were obtained remotely vs. in-person (p = 0.013), but the number of useable or better spots (at least 30-40uL of blood) did not differ (p = 0.89). Preference: A slight majority of participants (54%) preferred in-person DBS collection. Reliability: DBS test–retest reliabilities were good: CRP (ICC = 0.74), IL-6 (ICC = 0.76), and TNF-α (ICC = 0.70). Validity: Inflammatory levels from DBS correlated strongly with levels from venous blood (r = 0.60-0.99) and correlated as expected with sociodemographic and physical health and function variables. Older adults can remotely collect their own DBS to acquire reliable and valid inflammatory data. Remote DBS collection is highly feasible and may allow for inflammatory markers to be assessed in larger, more representative samples than are possible with lab- or clinic-based research designs. [ABSTRACT FROM AUTHOR]

Workplace‐collected blood spots deposited on filter paper were analysed with multiplexed affinity‐based protein assays and found to be suitable for proteomics analysis. The protein extension assay (PEA) was used to characterize 92 proteins using 1.2 mm punches in repeated samples collected from 20 workers. Overall, 97.8% of the samples and 91.3% of the analysed proteins passed quality control. Both within and between spot correlations using six replicates from the same individual were above 0.99, suggesting that comparable levels are obtained from multiple punches from the same spot and from consecutive spots. Protein levels from dried blood and wet serum from the same individuals were compared and the majority of the analysed proteins were found to be significantly correlated. These results open up for simplified sample collection of blood in field conditions for proteomic analysis, but also highlight that not all proteins can be robustly measured from dried whole blood. [ABSTRACT FROM AUTHOR]

Dried blood spots (DBSs) are formed by collecting a small sample of blood on specialized filter paper and allowing it to dry naturally. Various domains of life sciences and drug research extensively use DBSs as a sampling technique. The "Hematocrit (Ht) effect" affects assay bias, and several strategies have been put forth to deal with it, including the correction of quantified concentrations using an appropriate correction factor. The approach was previously applied, following the utilization of an image processing algorithm developed in Matlab® to derive a reliable equation correlating DBS areas to Ht% values. The present work looks more closely at the application of image analysis to the evaluation of Ht in DBS samples. Utilizing image analysis software, DBS samples with known Ht values were processed. Preparation of cards has followed a previously developed protocol for the appropriate formation of uniform area DBSs, irrespective of Ht. The resulting areas showed close resemblance to the respective theoretical areas calculated by applying the correlation equation. Following that, the equation was utilized to determine the Ht values for each sample, and a comprehensive comparison of measured versus calculated Ht was carried out using various statistical approaches for method comparison. The results demonstrated a strong correlation, suggesting the method's viability in estimating Ht for unknown DBS samples. [ABSTRACT FROM AUTHOR]

Background and Objectives: Serological diagnosis of hydatidosis is usually performed by detecting the circulating antibodies in serum by ELISA. The present study was carried out to standardize and evaluate procedure of the ELISA using elute from dried blood spots (DBS) on filter paper and blood stored at different temperatures and at different durations for its further application under field conditions. Materials and Methods: Dried blood spots were collected from fifty study subjects and fifty control subjects and evaluated for the detection of IgG antibodies against hydatid. Samples were stored at room temperature and 4°C and tested by ELISA at 0, 15 and 30 days. Results: The present study shows that elute of DBS on filter paper can be stored at room temperature for a maximum of 30 days without a decrease in antibody titer as compared to serum samples tested by ELISA. Conclusions: The collection of blood sample on filter paper may serve useful purpose in resource limited countries for carrying out sero-epidemiological surveys at a cost effective level. [ABSTRACT FROM AUTHOR]

Background: Real-time quantitative nucleic acid sequence-based amplification (QT-NASBA) is a sensitive method for detection of sub-microscopic gametocytaemia by measuring gametocyte-specific mRNA. Performing analysis on fresh whole blood samples is often not feasible in remote and resource-poor areas. Convenient methods for sample storage and transport are urgently needed. Methods: Real-time QT-NASBA was performed on whole blood spiked with a dilution series of purified in-vitro cultivated gametocytes. The blood was either freshly processed or spotted on filter papers. Gametocyte detection sensitivity for QT-NASBA was determined and controlled by microscopy. Dried blood spot (DBS) samples were subjected to five different storage conditions and the loss of sensitivity over time was investigated. A formula to approximate the loss of Pfs25-mRNA due to different storage conditions and time was developed. Results: Pfs25-mRNA was measured in time to positivity (TTP) and correlated well with the microscopic counts and the theoretical concentrations of the dilution series. TTP results constantly indicated higher amounts of RNA in filter paper samples extracted after 24 hours than in immediately extracted fresh blood. Among investigated storage conditions freezing at -20°C performed best with 98.7% of the Pfs25-mRNA still detectable at day 28 compared to fresh blood samples. After 92 days, the RNA detection rate was only slightly decreased to 92.9%. Samples stored at 37°C showed most decay with only 64.5% of Pfs25-mRNA detectable after one month. The calculated theoretical detection limit for 24 h-old DBS filter paper samples was 0.0095 (95% CI: 0.0025 to 0.0380) per µl. Conclusions: The results suggest that the application of DBS filter papers for quantification of Plasmodium falciparum gametocytes with real-time QT-NASBA is practical and recommendable. This method proved sensitive enough for detection of sub-microscopic densities even after prolonged storage. Decay rates can be predicted for different storage conditions as well as durations. [ABSTRACT FROM AUTHOR]

Abstract: A bioanalytical method for the determination of lumefantrine in 100μl blood applied onto sampling paper, by solid-phase extraction and liquid chromatography, has been developed and validated. Whatman 31 ET Chr sampling paper was pre-treated with 0.75M tartaric acid before sampling capillary blood to enable a high recovery of lumefantrine. Lumefantrine was extracted from the sampling paper, then further purified using solid-phase extraction and finally quantified with HPLC. The between-day variation was below 10% over the range 0.4–25μM. The lower limit of quantification was 0.25μM in 100μl capillary blood. No decrease in lumefantrine concentration in dried blood spot is seen after 4 months storage at 22°C. The method was also evaluated in field samples from patients in Tanzania after treatment with lumefantrine/artemether. Lumefantrine could be estimated accurately enough to assess bioavailability and treatment compliance on day 7 (i.e. 4 days after the last dose) after a standard regimen with the lumefantrine/artemether combination. [Copyright &y& Elsevier]

Background Detecting total cholesterol in dried blood spots could aid in identifying individuals with a high likelihood of familial hypercholesterolemia and could be used as a screening measure. This study aims to assess the diagnostic accuracy of dried blood spots on Whatman 903 paper cards using a manual enzymatic technique. Methods: A total of 394 samples were collected as serum and dried blood spots were compared. Cholesterol was determined in serum using the automated reference method, while cholesterol on paper was measured using a manual enzymatic method. Within- and between-day diagnostic variability were analyzed. The correlation between both methods was assessed using Passing–Bablok regression and Bland–Altman plot. Internal validation of our correlation formula was performed on 149 samples, along with external validation of the formula proposed by Corso et al. Results: The within- and between-day coefficient of variation was found to be lower than 10.14% and 14.09%, respectively. Passing–Bablok regression indicated a precision of 0.803 and an accuracy of 0.96. Internal validation precision was measured at 0.716. The resulting positive and negative predicted values were 0.77 and 0.92, respectively, vs. 0.46 and 0.96 from the external formula. Conclusions: Total cholesterol analysis in dried blood spots demonstrates high precision and reproducibility. This method reliably enables the incorporation of this biological marker into neonatal screening for familial hypercholesterolemia detection. [ABSTRACT FROM AUTHOR]

Dried Blood Spots (DBS) technology has become a valuable tool in medical studies, however, in veterinary and biological research DBS technology applications are still limited. Up-to-date no review has comprehensively integrated all the evidence existing across the fields, technologies and animal species. In this paper we summarize the current applications of DBS technology in the mentioned areas, and provide a scope of different types of dried sample carriers (cellulose and non-cellulose), sampling devices, applicable methods for analyte extraction and detection. Mammals, birds, insects and other species are represented as the study objects. Besides the blood, the review considers a variety of specimens, such as milk, saliva, tissue samples and others. The main applications of dried samples highlighted in the review include epidemiological surveys and monitoring for infections agents or specific antibodies for disease/vaccination control in households and wildlife. Besides the genetic investigations, the paper describes detection of environmental contaminants, pregnancy diagnosis and many other useful applications of animal dried samples. The paper also analyses dried sample stability and storage conditions for antibodies, viruses and other substances. Finally, recent developments and future research for DBS technology in veterinary medicine and biological sciences are discussed. [ABSTRACT FROM AUTHOR]

Abstract: The level of T-cell receptor excision circles (TREC), which decline with advancing age in normal individuals, has recently gained interest as a reference marker for studies on premature or early immunosenescence under particular health conditions. In order to facilitate translational studies at population and clinical levels, essential for the understanding of how changes in TREC levels are associated with responsiveness of the immune system, we have developed and optimized a real-time polymerase chain reaction (qPCR) assay which quantifies the TREC ratio from dried blood spot (DBS) samples. The present study considers a fully automated procedure to purify DNA and amplify sequences of interests by means of qPCR from DBS samples collected in healthy adults. Both TREC:PBMC (peripheral blood mononuclear cell) and TREC:T-cell ratios were compared for intra- and inter individual reproducibility. Furthermore, the impact of the length of storage on the quality of the DNA generated was also analyzed. In conclusion we describe a fully automated procedure for extracting DNA and qPCR set up, which offers a high-precision, robust qPCR assay for the quantification of both TREC:T-cell ratio and TREC:PBMC from DBS samples. [Copyright &y& Elsevier]

Finger or heel-pricked blood sampling for fatty acid analysis is suitable especially in newborn infants where blood sampling is difficult and phlebotomy for research can be unethical. The aim of this study was to evaluate dried blood long chain polyunsaturated fatty acids (LC-PUFA) stability during storage at −28 °C. We collected 12 blood cord samples that were analyzed immediately after blood drawing, with and without drying the blood on filter paper. Dried samples were then analyzed 7 days and 1, 3, and 6 months after collection. Butylated hydroxytoluene was added to all samples. Fatty acid composition and C enrichment were measured by gas chromatography and by gas chromatography-isotope ratio mass spectrometry, respectively. The fatty acid composition, expressed in mol%, of the major LC-PUFA at day 7 was not statistically different from time 0, however lower values were found by the first month of storage. The C enrichment of 20:4n-6 and 22:6n-3 did not differ during the whole study period. LC-PUFA analysis from dried umbilical cord blood in neonates should be performed within a week, major losses of LC-PUFA occur afterwards. However, fatty acids obtained from dried blood maintain their C enrichment value for up to 6 months and thus these samples are suitable for natural abundance isotopic studies. [ABSTRACT FROM AUTHOR]

Because of the various matrices available for forensic investigations, the development of versatile analytical approaches allowing the simultaneous determination of drugs is challenging. The aim of this work was to assess a liquid chromatography-tandem mass spectrometry (LC-MS/MS) platform allowing the rapid quantification of colchicine in body fluids and tissues collected in the context of a fatal overdose. For this purpose, filter paper was used as a sampling support and was associated with an automated 96-well plate extraction performed by the LC autosampler itself. The developed method features a 7-min total run time including automated filter paper extraction (2 min) and chromatographic separation (5 min). The sample preparation was reduced to a minimum regardless of the matrix analyzed. This platform was fully validated for dried blood spots (DBS) in the toxic concentration range of colchicine. The DBS calibration curve was applied successfully to quantification in all other matrices (body fluids and tissues) except for bile, where an excessive matrix effect was found. The distribution of colchicine for a fatal overdose case was reported as follows: peripheral blood, 29 ng/ml; urine, 94 ng/ml; vitreous humour and cerebrospinal fluid, < 5 ng/ml; pericardial fluid, 14 ng/ml; brain, < 5 pg/mg; heart, 121 pg/mg; kidney, 245 pg/mg; and liver, 143 pg/mg. Although filter paper is usually employed for DBS, we report here the extension of this alternative sampling support to the analysis of other body fluids and tissues. The developed platform represents a rapid and versatile approach for drug determination in multiple forensic media. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Background: This study evaluates HbA1c measurements from dried blood spots collected on filter paper and compares HbA1c from filter paper (capillary blood) with HbA1c measured in venous blood. Methods: Patient satisfaction was evaluated using a questionnaire. The performance with the filter paper method was assessed by comparing HbA1c results from EDTA-blood samples obtained via dried blood spots with HbA1c results obtained with freshly hemolyzed blood (routine HbA1c). Adult patients visiting the outpatient clinic for HbA1c analyses were recruited for the evaluation of dried blood spot sampling at home. Laboratory personnel collected a capillary blood sample on filter paper as well as a venous EDTA-blood sample. The participants collected another capillary blood sample at home and sent the dried filter paper back to the laboratory. Samples were analyzed with an immunoturbidimetric assay. Results: Between-filter coefficient of variation was 1.8%. Filter paper HbA1c increased slightly during storage, particularly during the first 5 days. Filter paper HbA1c highly correlated with routine HbA1c (r=0.987). The evaluation of samples collected at home showed comparable HbA1c values by filter paper and routine sampling methods (n=93). Eighty-three percent of participants said they would like the filter method to be brought into practice. Conclusions: Home HbA1c sampling on filter paper is an acceptable sampling alternative for analysis of HbA1c. Clin Chem Lab Med 2009;47:1259–64. [ABSTRACT FROM AUTHOR]

Dried matrix spot (DMS) is a sampling technique, primarily used to analyze blood to diagnose metabolic diseases in newborns. As this technique has several advantages, DMS has started to be employed for other purposes using other biological matrices and increasingly in toxicology over the last decade. The aim of this work was to review the analytical methods using DMS which can be applied to drugs of abuse and which have been published since 2010. Three different databases were searched, using dried, spots, and drugs of abuse as the descriptors and using a snowball search. After applying the exclusion criteria, 39 papers remained. The most common publications were related to the use of blood, which corresponded to 77% of the papers, followed by urine and oral fluid, which corresponded to 13 and 10% of the papers, respectively. The selected studies covered different illicit drugs, sample sizes of 5 to 250 µL and spot sizes ranging from 3 to 18 mm in diameter. This review also examined the extraction techniques and the methods employed to analyze various biological matrices and drugs of abuse, mostly by liquid-extraction and liquid chromatography-tandem mass spectrometry. The benefits of DMS include: a simple sample pretreatment, better stability than liquid matrices, a simple extraction procedure, lower costs, and environmental benefits. DMS appears to be a promising technique in the field of toxicology and provides new perspectives for use in forensic laboratories. [ABSTRACT FROM AUTHOR]

The level of neutralizing antibodies required to confer protection against COVID-19 breakthrough infections (BIs) is unclear, and the ability to know the immune status of individuals against the rapidly changing endemic variants is limited. We assessed longitudinal serum anti-RBD antibody levels and neutralizing activities (NTs) against Omicron BA.5 and XBB.1.5 in healthcare workers following the fourth monovalent and fifth bivalent BA.4–5 vaccines. The occurrence of BIs was also followed, and pre-infection antibody levels were compared between patients who developed BI and those who did not. In addition, we collected whole blood samples on the same day as the sera and stored them on filter papers (nos. 545, 590, and 424) for up to two months, then measured their NTs using dried blood spots (DBS) eluates, and compared them with the NTs in paired sera. Pre-infection levels of NTs were lower in patients who developed BI than those who did not, but the anti-RBD antibody levels were not different between them. The NTs below 50 % using 200-fold diluted sera might be one of the indicators of high risk for COVID-19 BI. However, the NTs against XBB.1.5 at 6 months after the fifth dose of bivalent BA.4–5 vaccine were lower than this threshold in almost half of infection-naïve participants. NTs measured using DBS eluates were strongly correlated with those measured using paired sera, but the time and temperature stability varied with the type of filter paper; no. 545 filter paper was found to most suitable for NT evaluation. [ABSTRACT FROM AUTHOR]

Background: Dried blood spot (DBS) testing is a well-known method of bio-sampling by which blood samples are blotted and dried on filter paper. The dried samples can then be analyzed by several techniques such as DNA amplification and HPLC. We have developed a non-invasive sampling followed by an alternative protocol for genomic DNA extraction from a drop of blood adsorbed on paper support. This protocol consists of two separate steps: (1) organic DNA extraction from the DBS, followed by (2) DNA amplification by polymerase chain reaction (PCR). The PCR-restriction fragment length polymorphism (PCR-RFLP) is an advantageous and simple approach to detect single nucleotide polymorphisms (SNPs). Results: We have evaluated the efficiency of our method for the extraction of genomic DNA from DBS by testing its performance in genotyping mouse models of obesity and herein discuss the specificity and feasibility of this novel procedure. Conclusions: Our protocol is easy to perform, fast and inexpensive and allows the isolation of pure DNA from a tiny amount of sample. [ABSTRACT FROM AUTHOR]

Dried blood spots (DBS) have proven to be a powerful sampling and storage method for newborn screening and many other applications. However, DBS methods have not yet been optimized for broad-spectrum targeted metabolomic analysis. In this study, we developed a robust, DBS-based, broad-spectrum, targeted metabolomic method that was able to measure over 400 metabolites from a 6.3 mm punch from standard Whatman 903TM filter paper cards. The effects of blood spot volumes, hematocrit, vacutainer chemistry, extraction methods, carryover, and comparability with plasma and fingerstick capillary blood samples were analyzed. The stability of over 400 metabolites stored under varying conditions over one year was also tested. No significant impacts of blood volume and hematocrit variations were observed when the spotted blood volume was over 60 µL and the hematocrit was between 31% and 50%. The median area under the curve (AUC) of metabolites in the DBS metabolome declined by 40% in the first 3 months and then did not decline further for at least 1 year. All originally detectable metabolites remained within detectable limits. The optimal storage conditions for metabolomic analysis were −80 °C with desiccants and without an O2 scavenger. The method was clinically validated for its potential utility in the diagnosis of the mitochondrial disease mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS). Our method provides a convenient alternative to freezing, storing, and shipping liquid blood samples for comparative metabolomic studies. [ABSTRACT FROM AUTHOR]

Dried blood spots (DBSs), a micro-sampling technique whereby a drop of blood is collected on filter paper has multiple advantages over conventional blood sampling regarding the sampling itself, as well as transportation and storage. This is the first paper describing the development and validation of a method for the determination of 23 mycotoxins and phase I metabolites in DBSs from pigs and broiler chickens using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The targeted mycotoxins belong to groups for which the occurrence in feed is regulated by the European Union, namely, aflatoxins, ochratoxin A and several Fusarium mycotoxins, and to two groups of unregulated mycotoxins, namely Alternaria mycotoxins and Fusarium mycotoxins (enniatins and beauvericin). The impact of blood haematocrit, DBS sampling volume and size of the analysed DBS disk on the validation results was assessed. No effects of variation in size of the analysed disk, haematocrit and spotted blood volume were observed for most mycotoxins, except for the aflatoxins and β-zearalanol (BZAL) at the lowest haematocrit (26%) level and for the enniatins (ENNs) at the lowest volume (40 µL). The developed method was transferred to an LC-high resolution mass spectrometry instrument to determine phase II metabolites. Then, the DBS technique was applied in a proof-of-concept toxicokinetic study including a comparison with LC-MS/MS data from plasma obtained with conventional venous blood sampling. A strong correlation (r > 0.947) was observed between plasma and DBS concentrations. Finally, DBSs were also applied in a pilot exposure assessment study to test their applicability under field conditions. [ABSTRACT FROM AUTHOR]

The objective of this work was to compare the quality, purity and quantity of DNA isolated from dried blood spots (DBS) by three methods (Chelex-100, QIAamp DNA mini kit, and TE (Tris EDTA)-Buffer). Sample collection was performed in six districts in Odisha, India and screened for cases of clinical malaria and dengue and vector density. Mosquito abdomens were spotted on Whatman 3MM (MERCK) Filter paper and dried for 10 min at room temperature. DNA was isolated from DBS using three methods (Chelex-100, QIAamp DNA mini kit, and TE-Buffer), and PCR was used to determine the feeding behaviours of vector mosquitoes. DNA was quantified using a UV-spectrophotometer, and q-PCR was used to determine the target gene copy number to compare the methods. The QIAamp DNA mini kit method was used as the reference method. The yield and purity of DNA extracted with Chelex-100 and TE were 14-72 ng/µl and 1.51-1.85 and 9-50 ng/µl and 1.68-2.1, respectively. DNA extracted using the Chelex-100 method was stored for over 1 month at − 20 °C and was suitable for later use. The Chelex-100 method had a sensitivity of 99.5% and specificity of 78%. A Bland-Altman plot suggested that the Chelex-100 method was similar to the QIAamp DNA mini kit method for determining the feeding behaviours of vector mosquitoes. The Chelex-100 method is simple, cost-effective, and safe and requires minimal time for DNA extraction from dried blood spots. In malaria and dengue research, detecting the feeding behaviours from mosquito DNA from dried blood spots on filter paper by PCR is an easy, minimally invasive and inexpensive molecular technique that can be performed in remote areas. [ABSTRACT FROM AUTHOR]

Summary: A method for the determination of sulfadoxine and sulfamethoxazole in capillary blood on sampling paper has been developed and validated. The method is straightforward with minimal sample preparation, and is suitable for rural settings. Separation of sulfadoxine, sulfamethoxazole and internal standard was performed using a Purospher STAR RP-18 endcapped LC column (150×4.6mm) with a mobile phase consisting of acetonitrile:sodium acetate buffer pH 5.2, I=0.1 (1:2, v/v). For sulfadoxine, the within-day precision was 5.3% at 15μmol/l and 3.7% at 600μmol/l, while for sulfamethoxazole it was 5.7% at 15μmol/l and 3.8% at 600μmol/l. The lower limit of quantification was determined to 5μmol/l and precision was 5.5% and 5.0% for sulfadoxine and sulfamethoxazole, respectively. [Copyright &y& Elsevier]

• Both dyadic and self-sampling of dried blood spots is feasible. • Protocols are available for endocrine, immune, genetic and epigenetic markers. • Dried blood spots can be an alternative to venous blood or saliva sampling. • However, this highly depends on the parameter of interest. • Dried blood spots are also useful with large and remotely located study populations. The term "dried blood spot" (DBS) refers to a sampling technique in which capillary whole blood is spotted on filter paper. Given the possibility to determine a wide range of hormones and related biomarkers in DBS, the method should be of interest to researchers in psychoneuroendocrinology. So far, however, the how and when of using DBS in this context have not been outlined. A review of the literature was conducted in order to describe the materials and procedures necessary to determine relevant biological markers from DBS (how to use DBS). In addition, a comparison of the DBS method with other sampling techniques was undertaken and examples of its previous use in psychoneuroendocrinology were provided (when to use DBS). Both dyadic and DBS self-sampling are feasible, and a number of protocols are available to determine endocrine and immune, genetic and epigenetic markers. Decisions to use DBS instead of venous blood or saliva sampling should mainly be guided by whether it is sensible and feasible to determine the parameter of interest in whole blood obtained from DBS. In addition, DBS are well suited for large study populations with specific vulnerabilities, and for remotely located studies with budgetary constraints. Dried blood spots are a promising material as well as a simple sampling technique for psychoneuroendocrinological research. Future efforts should be directed at continuing to adapt existing serum and plasma analysis protocols for use with DBS, and at testing the feasibility of DBS self-sampling in field studies. [ABSTRACT FROM AUTHOR]

[Display omitted] • Evaluation of a near-infrared set-up for the prediction of the hematocrit. • Successful validation with excellent accuracy and precision results. • Robustness experiments were performed to ensure the applicability in clinical practice. • Application on capillary DBS samples obtained via finger prick was included. Dried blood spot (DBS) microsampling has gained interest in different clinical fields, owing to its many advantages compared to conventional blood sampling. However, whilst being applied for decades for screening purposes, some challenges, such as the hematocrit (Hct) effect, hinder further widespread use of DBS for quantitative purposes in clinical practice. Amongst the approaches that were developed to cope with this issue, is the Hct prediction of DBS using near-infrared (NIR) spectroscopy. Using left-over EDTA-anticoagulated patient samples, the accuracy and precision, stability, and robustness were assessed. Furthermore, applicability of the method on capillary DBS was evaluated via finger prick samples. A maximal bias, respectively CV, of 0.012 L/L and 4.5% were obtained. The method was robust towards several aspects, including storage (except for storage at 60°C), measurement location, type of filter paper and spotted volume. Furthermore, the potential to predict the Hct of capillary DBS was demonstrated. A commercially available NIR set-up was extensively and successfully validated, allowing non-contact Hct prediction of DBS with excellent accuracy and precision. This allows to correct for the Hct-based bias observed in partial-punch DBS analysis and the set-up of blood-plasma conversion factors, increasing the application potential of patient-centric sampling. [ABSTRACT FROM AUTHOR]

Objectives: Conduction of pharmacokinetic (PK) study in pediatric patients is challenging due to blood sampling limits. The dried blood spots (DBS) method represents a potential matrix for microsampling in support of PK studies in children. Herein, we used the Capitainer® qDBS device to develop a DBS method that can collect an exact 10 µL volume of blood on a paper card. This DBS method was developed to simultaneously quantify the concentrations of eight antibiotics, including sulbactam, tazobactam, ampicillin, meropenem, cefotaxime, cefoperazone, piperacillin, and metronidazole using ultra-high performance liquid chromatography–tandem mass spectrometry (UHPLC–MS/MS). Methods: The prepared DBS samples were extracted in methanol containing acetaminophen as the internal standard at 20 °C on a block bath shaker at 500 rpm for 30 min. The extracted antibiotics were eluted on an Acquity UPLC HSS T3 column (2.1 × 50 mm, 1.8 µm) using gradient elution with a total chromatographic run time of 6.5 min. The precursor and product ions of the analytes were detected by use of the multiple reaction monitoring (MRM) mode. Results: No interfering peaks at the respective retention times of the analytes were observed in DBS samples. The lower limits of quantification (LLOQ) for the antibiotics were between 0.25 and 2.0 μg/mL, and satisfactory accuracies (intra/inter-assay bias −16.7 to +13.6%) and precisions (intra/inter-assay coefficient of variations 1.5–15.6%) were obtained for the analytes. As a proof of concept, the method was applied to DBS samples obtained from neonatal patients treated with ampicillin and piperacillin/sulbactam. Conclusions: The DBS method is simple and robust, and it can be used in children with limited blood sampling. [ABSTRACT FROM AUTHOR]

The detection of nitazenes in biological fluids is increasingly needed as they are repeatedly reported in intoxication and overdose cases. A simple method for the quantification of low levels of nine nitazene analogs and brorphine in Dried Blood Spots (DBS) was developed and validated. 10 μL of spiked whole blood is deposited on a Capitainer®B card and allowed to dry. The spot is punched out, and extracted with 500 μL methanol:acetonitrile (3:1 v/v) added with 1.5 μL of fentanyl-D5 as the internal standard. After stirring, sonication, and centrifugation of the vial, the solvent is dried under nitrogen, the extract is reconstituted in 30 μL methanol, and 1 μL is injected into a UHPLC-MS/MS instrument. The method validation showed linear calibration in the 1–50 ng/mL range, LOD values ranging between 0.3 ng/mL (isotonitazene) and 0.5 ng/mL (brorphine), average CV% and bias% within 15 % and 10 % for all compounds, respectively. The matrix effect due to blood and filter paper components was within 85–115 % while recovery was between 15–20 %. Stability tests against time and temperature showed no significant variations for storage periods up to 28 days. Room temperature proved to represent the best samples storage conditions. UHPLC-MS/MS proved capable to reliably identify all target analytes at low concentration even in small specimen volumes, as those obtained from DBS cards, which in turn confirmed to be effective and sustainable micro-sampling devices. This procedure improves the efficiency of toxicological testing and provides an innovative approach for the identification of the nitazene class of illicit compounds. • An innovative approach for the identification of nitazenes and brorphine is presented. • Quantitative determination of 10 new synthetic opioids in DBS was achieved. • The stability of nitazenes in spiked DBS samples was evaluated. • Monitoring the diffusion of opioids in selected populations is possible. [ABSTRACT FROM AUTHOR]

Dried blood spots (DBS) are being considered as an alternative sampling method of blood collection that can be used in combination with lipidomic and other omic analysis. DBS are successfully used in the clinical context to collect samples for newborn screening for the measurement of specific fatty acid derivatives, such as acylcarnitines, and lipids from whole blood for diagnostic purposes. However, DBS are scarcely used for lipidomic analysis and investigations. Lipidomic studies using DBS are starting to emerge as a powerful method for sampling and storage in clinical lipidomic analysis, but the major research work is being done in the pre- and analytical steps and procedures, and few in clinical applications. This review presents a description of the impact factors and variables that can affect DBS lipidomic analysis, such as the type of DBS card, haematocrit, homogeneity of the blood drop, matrix/chromatographic effects, and the chemical and physical properties of the analyte. Additionally, a brief overview of lipidomic studies using DBS to unveil their application in clinical scenarios is also presented, considering the studies of method development and validation and, to a less extent, for clinical diagnosis using clinical lipidomics. DBS combined with lipidomic approaches proved to be as effective as whole blood samples, achieving high levels of sensitivity and specificity during MS and MS/MS analysis, which could be a useful tool for biomarker identification. Lipidomic profiling using MS/MS platforms enables significant insights into physiological changes, which could be useful in precision medicine. [ABSTRACT FROM AUTHOR]

Dried blood spots (DBS) are formed by deposition of a small amount of blood on specific adsorbent paper and its physical drying. DBS are employed as a sampling method in several fields of life sciences and drug research. A concern about DBS is the so-called 'Hematocrit (Ht) effect', as a different Ht leads, due to different viscosity, to different spot size, affecting assay bias. Solutions have been proposed, including the correction of quantified concentrations with a suitable correction factor. In order to quantitatively assess Ht impact on the DBS measurements, a computational approach was developed and implemented in R® language. First, the % relative error was modeled with respect to Ht. Then, Monte Carlo simulations were performed in virtual men/women populations with different Ht levels and the % relative error in relation to the Ht used for calibrators was quantified. An upper level for % relative error being a 'tolerable contribution' of Ht effect to % total analytical error was finally suggested, defining, for the first time, a potential Ht range for analysis of adults' samples, where correction of concentrations of unknown samples may be omitted. Such tolerable level for % relative error may be defined in each laboratory, also based on experimental parameters (type of paper and blood volume). Using a Ht calibration value representing the study population is fully rationalized, leading to reduced probability for concentration corrections. Regulatory criteria for bioanalysis can thus be targeted, moving towards wider utilization of DBS in human pharmacokinetic and clinical trials. [ABSTRACT FROM AUTHOR]

Background: Real-time polymerase chain reaction (PCR) is a sensitive and specific method for diagnosing schistosomiasis. However, this method should be performed in a laboratory, usually located distant from the sample collection site. Therefore, it is important to have fast sampling preservation methods, which allow simple transport prior to DNA extraction and amplification. The aim of this study was to verify if blood samples applied to filter paper are suitable for analysis of Schistosoma mansoni DNA by real-time PCR. Methods: A cross-sectional study was conducted among 100 study participants aged 17 to 70 years in a fishing village on the southern shore of Lake Victoria, Tanzania. Serum samples and ethylenediaminetetraacetic acid (EDTA)-anticoagulated whole blood for preparation of dried blood spots (DBS) were collected to test for Schistosoma mansoni infection by real-time PCR. A combined diagnostic reference of positive results of serum-based real-time PCR and the Kato-Katz (KK) method was used for analysis. Sensitivity and negative predictive value (NPV) were calculated. The Wilcoxon signed-rank test was chosen to compare the mean cycle threshold (Ct) values from serum and DBS. Results: According to the reference, 92.5% S. mansoni positive samples were determined. The serum-based real-time PCR performed excellently with 95.4% sensitivity, whereas the DBS-based real-time PCR showed a low sensitivity (45.4%). The Ct-values were significantly higher in DBS (median: 37.3) than in serum samples (median: 27.5, P < 0.001), reflecting a lower parasite-specific DNA load on the filter cards. With increasing egg counts, an increase in sensitivity was observed for all methods. The POC-CCA test and the serum-based real-time PCR showed a sensitivity of 100% for medium and severe infections. The DBS real-time PCR showed a sensitivity of only 85.7% even for severe infections. Conclusions: DBS-based real-time PCR did not provide good results in our study and therefore should not be recommended or must be tested concerning temperature of storage, storage duration, use of different filter papers and extraction methods before it is used in future studies. In contrast, our results showed that the POC-CCA test is a sensitive and precise test for detecting S. mansoni infections. [ABSTRACT FROM AUTHOR]

Background: Newborn screening (NBS) is an established screening procedure in many countries worldwide, aiming at the early detection of inborn errors of metabolism. For decades, dried blood spots have been the standard specimen for NBS. The procedure of blood collection is well described and standardized and includes many critical pre-analytical steps. We examined the impact of contamination of some anticipated common substances on NBS results obtained from dry spot samples. This possible preanalytical source of uncertainty has been poorly examined in the past. Methods: Capillary blood was obtained from 15 adult volunteers and applied to 10 screening filter papers per volunteer. Nine filter papers were contaminated without visible trace. The contaminants were baby diaper rash cream, baby wet wipes, disinfectant, liquid infant formula, liquid infant formula hypoallergenic (HA), ultrasonic gel, breast milk, feces, and urine. The differences between control and contaminated samples were evaluated for 45 NBS quantities. We estimated if the contaminations might lead to false-positive NBS results. Results: Eight of nine investigated contaminants significantly altered NBS analyte concentrations and potentially caused false-positive screening outcomes. A contamination with feces was most influential, affecting 24 of 45 tested analytes followed by liquid infant formula (HA) and urine, affecting 19 and 13 of 45 analytes, respectively. Conclusions: A contamination of filter paper samples can have a substantial effect on the NBS results. Our results underline the importance of good pre-analytical training to make the staff aware of the threat and ensure reliable screening results. [ABSTRACT FROM AUTHOR]

Background. African elephants in managed care have presented differences in the balance between omega-3 and omega-6 fatty acids, a situation primarily thought to be due to dietary differences between the managed animals and their free-ranging counterparts. Because of this, circulating fatty acid status is included in routine monitoring of elephant health. A method of blood collection that requires only a few drops of whole blood, dried on filter paper (DBS) and can be used for analyzing full fatty acid profiles offers advantages in clinical application. Methods. This study compared the use of whole blood, and whole blood DBS, serum or plasma for use in evaluating circulating fatty acid composition in African savannah elephants. Samples from six African elephants (two males and four females) were collected during the same week at the NC Zoo, Asheboro, NC. Results. Results found only 2 of 36 individual fatty acids and none of the 10 fatty acid groupings were different when comparing the four blood fraction sample types to each other with Mann-Whitney U-Test pairwise comparisons. Myristic acid (14:0) was lower in the DBS samples than in whole blood, serum, and plasma and pentadecaenoic acid (15:1) was slightly more concentrated in DBS and whole blood. Discussion. Results indicate that fatty acid profile of serum, plasma, whole blood, and DBS are comparable in African elephants. The DBS method offers advantages in acquisition and handling and may be preferable to other methods in both routine health assessment of captive animals and field research on free ranging animals. [ABSTRACT FROM AUTHOR]

Biomonitoring studies of vulnerable populations in low‐ and middle‐income countries are limited because traditional sampling methods are challenging to implement in low‐resource settings. The present study examined the feasibility, precision, and accuracy of dried blood spots (DBS) for human biomonitoring of nonessential elements (cadmium [Cd], mercury [Hg], and lead [Pb]) in an area of northern Tanzania with artisanal and small‐scale gold mining activities. Pregnant women (n = 44) were recruited in Geita during antenatal clinic visits, and DBS from capillary blood were collected on filter paper. As a gold‐standard comparison, venous blood was sampled from the same participants and compared with the DBS. Venous blood, DBS, and quality control samples were analyzed for chemical elements by inductively coupled plasma mass spectrometry. Field blanks were very clean for most elements, generally only twice as high as corresponding laboratory filter blanks. No significant differences were found between duplicate DBS samples taken from the same participants, with near perfect intraclass correlation coefficients (0.99) for Cd, Hg, and Pb, indicating excellent reliability. Moreover, correlation was strong (r2 > 0.9) and significant (p < 0.0001) between DBS and the quantitative venous blood, with regression line slopes close to 1.0 (0.847, 0.976, and 0.969 for Cd, Hg, and Pb, respectively), indicating high accuracy of the DBS method compared with the gold‐standard approach. The DBS method is minimally invasive and was a feasible, precise, and accurate means of measuring exposure to Cd, Hg, and Pb in pregnant women in a low‐resource setting. Environ Toxicol Chem 2019;38:1285–1293. © 2019 SETAC [ABSTRACT FROM AUTHOR]

Introduction: Storing blood as dried spots on filter paper is a trustworthy approach used in genetic screening issues which justifies the necessity for a reliable DNA extraction method. The present work aims to investigate the effectiveness of superparamagnetic-bead based method in extracting DNA from dried blood spots (DBS). Materials and Methods: Sixteen venous blood samples collected in K3-EDTA tubes (400μl of whole blood) were used for the spotting (4 circles each 100μl) on Ahlstrom 226 grad filter papers, for extraction and comparison. To ensure effectiveness, the extracted DNA was checked for quantity using the Quant-iT™ dsDNA Broad-Range Assay Kit and for quality by polymerase chain reaction (PCR) amplification of 344 bp segment of the HBB gene. Hybridization assays based on the dynamic allele specific hybridization (DASH) technique for two hemoglobin beta (HBB) mutations in genomic DNA extracted from DBS of β-thalassemia patients were also performed to ensure the quality of extraction. Results: The results revealed a compatible effectiveness of the superparamagnetic-bead based method in extracting DNA from DBS particularly when incubating the DBS with lysis buffers BL+BLM overnight. A mean concentration of 21ng/μl was obtained with lysis buffers BL+BLM overnight incubation compared to 5.2 ng/μl for 2 h incubation with lysis buffers BL+BLM and 4.7 ng/ μl when extraction performed using the lysis buffer BLM alone. Moreover, PCR amplification of 344 bp segment of the HBB showed a good quality of the extracted DNA. Conclusion: It was concluded that the superparamagnetic-bead based method is a reliable and effective method for DNA extraction from DBS and can be adopted for genetic diagnostic purposes. [ABSTRACT FROM AUTHOR]

Storage of dried blood spots ( DBS) on high-density FTA® plates could constitute an appealing alternative to frozen storage. However, it remains controversial whether DBS are suitable for high-resolution sequencing of human leukocyte antigen ( HLA) alleles. Therefore, we extracted DNA from DBS that had been stored for up to 4 years, using six different methods. We identified those extraction methods that recovered sufficient high-quality DNA for reliable high-resolution HLA sequencing. Further, we confirmed that frozen whole blood samples that had been stored for several years can be transferred to filter paper without compromising HLA genotyping upon extraction. Concluding, DNA derived from high-density FTA® plates is suitable for high-resolution HLA sequencing, provided that appropriate extraction protocols are employed. [ABSTRACT FROM AUTHOR]

Exposures to heavy metals during fetal and perinatal development are of particular concern. Yet, the health impacts of exposures to toxic metals during these early stages of human development are not well understood due to the paucity of in vivo human data. Dried blood spots (DBS), collected by public health departments to screen for inherited metabolic errors and other disorders, are routinely archived and can be used for exposure assessment. Here we report an improved method for quantifying arsenic, lead, mercury and cadmium in newborn DBS to facilitate epidemiologic research on the health effects of early exposures to toxic metals. [ABSTRACT FROM AUTHOR]

Dried blood spots (DBS) are widely used to test for HIV in a variety of research and service delivery settings; however, uniform guidelines regarding collection, storage and DNA extraction processes have neither been developed nor evaluated. Previously published reports suggested DBS may be stored at room temperature for up to 60 days, and intensive stability tests have shown that DBS can withstand high temperatures, humidity and freeze-thawing. During the implementation of a large randomized controlled trial (RCT) in southern Africa, with HIV acquisition as the primary endpoint, we observed 65 instances when DBS samples collected from the same day as a positive HIV antibody test yielded negative DNA polymerase chain reaction (PCR) results. The source of this discrepancy may have been due to inadequate specimen volume, filter paper or DNA extraction procedures, but were most likely due to storage conditions that have been reported as acceptable in other settings [ABSTRACT FROM AUTHOR]

Dried blood spots (DBS) on filter paper provide a simple and convenient means of collecting, storing and shipping samples for veterinary diagnostics related to toxin exposures. This paper presents validation data on analysis of DBS for chlorinated persistent organic pollutants, specifically 4,4′-dichloro-diphenyl-trichloroethane (4,4′-DDT) and its breakdown product 4,4′-dichlorodiphenyl-dichloroethylene (4,4′-DDE), lindane and a representative polychlorinated biphenyl (PCB) congener PCB-153. Analysis was by gas chromatography with electron capture detection (GC-ECD). The method required one 12.5 mm diameter spot representing application of 50 μL of blood, and working limits of detection (LOD) for each of the compounds was 5 ppb. Data are presented on development and description of the method, assay precision, LOD and quantitation, linearity, accuracy, specificity, effects of long-term storage and ruggedness. The method was also applied to 27 avian DBS, and 4,4′-DDE was detected in the majority of samples. [ABSTRACT FROM PUBLISHER]

• Volume and hematocrit of blood applied to filter paper collection devices affects test results. • Volume of blood assumed to be in 3.2 mm filter paper sub-punch is incorrect resulting in bias. • Volumetric devices negate these pre-analytical issues, improving precision and accuracy. • Devices integrate easily into the workflow of the routine screening/metabolic laboratory. • Volumetric devices will improve biochemical monitoring of patients with Phenylketonuria. Measurement of dried blood spot (DBS) phenylalanine (Phe) is central to the monitoring of patients with phenylketonuria. However, the volume and hematocrit (Hct) of the blood applied to conventional DBS cards significantly affects analytical results. Volumetric blood collection devices are reported to be more accurate, precise and less prone to Hct effects. Accuracy, imprecision, effect of blood volume and Hct were evaluated for measurement of Phe and tyrosine using three volumetric devices and compared with the conventional PerkinElmer-226 filter-paper collection devices. i.e. conventional DBS cards. Applicability for use in a clinical laboratory was assessed qualitatively. Blood volume did not impact on the performance of the volumetric devices; however, significant biases were observed with the conventional DBS card. A higher Hct introduced unacceptable bias for Neoteryx-Mitra and conventional DBS card. All devices had a mean relative standard deviation (RSD) ≤ 4.1 %, except for the Neoteryx-Mitra (≤ 6.2 %). Relative to liquid blood, the mean biases of Phe for the various devices were −5.1 (HemaXis-DB10), −7.8 (Capitainer-qDBS), −12.0 (Neoteryx-Mitra) and −32.6 % (conventional DBS card). Introducing volumetric collection devices will overcome the significant pre-analytical issues associated with conventional DBS collection and improve the biochemical monitoring of patients with PKU. [ABSTRACT FROM AUTHOR]