Clinical Validation of an Automated Dried Blood Spot Sampling Device – Fluispotter® Khem Adhikari (Presenter) Rigshospitalet Presenter Bio: I am in the third year of my postdoc research career and in the second year of my current position. I did my PhD in Analytical Chemistry from Denmark (2014) and MSc in Nutritional Sciences (2009) from Israel. Currently, I am working on an analytical method development and validation for cortisol in dried blood spot (DBS) as a part of the project for clinical validation of an automatic, wearable, 20-hours DBS sampling device. I apply the-state-of-art mass spectrometry instruments in various uses of clinical, food/nutrition, agriculture, clinical and environmental aspects. Since 2011 method development, validation, quality control, quantitative analysis and metabolite identification in various matrices has been my main focus. It primarily covers various sample preparation processes, LC-MS/MS method development and validation, sample and data analyses.

Authors: Khem Bahadur Adhikari1*, Ruth Frikke-Schmidt (1), Ulla Feldt-Rasmussen (2), Jesper Johannesen (3), Sten Velschow (4), Malene Schrøder (4), Anders Holten Johnsen (1)
(1) Department of Clinical Biochemistry, Rigshospitalet, Copenhagen, Denmark (2) Department of Endocrinology, Rigshospitalet, Copenhagen, Denmark (3) Department of Paediatrics, Herlev Hospital, Copenhagen, Denmark (4) Fluisense ApS, Lillerød, Denmark

The use of dried blood spot (DBS) samples for the quantitative analysis has received increasing attention in the recent years. An accurate micro-volume spotting, 20-hours, automated and wearable DBS sampler, “Fluispotter®”, has been used and the analytical method for cortisol has been thoroughly validated as proof of concept. The method has good precision and accuracy and the device is well suited for clinical trials.

Introduction

There is an increasing interest of quantitative dried blood spot (DBS) analysis in recent years. There are a few commercial automatic DBS samplers, but they are not wearable and involve high volume sampling which consequently are affected by hematocrit bias. We have developed and validated an analytical method for cortisol using a novel accurate volume-based, automated, wearable, 20-hours DBS sampler, “Fluispotter®”, which provides micro-sampling with the potential to overcome issues associated to HCT.

Methods

Fluispotter® was used to deposit 10 µl blood samples in a series of up to 20 DBS samples in PerkinElmer 226 filter paper. After drying and storage, the DBS samples were punched and extracted with acetonitrile/water (80/20) and analyzed by WatersTM AcquityTM UPLC system coupled with WatersTM Xevo® TQ-S mass spectrometer.

Results

Fluispotter® was able to produce in-house DBS-calibrators and quality control samples with variations within acceptable limits (<10% CV). Furthermore, the analytical method developed for the analysis of cortisol in DBS samples had good accuracy (recoveries 97 to 109%) and precision (CV<10%) at three different levels (low, medium and high). When sub punch samples were analyzed, a significant positive linear analytical bias was observed with increasing HCT levels (±40%, from HCT 0.3 to 0.6) compared to the values at 0.45 HCT. This was primarily a consequence of positive area bias with increasing HCT, but no notable changes of recovery and suppression bias were observed across the HCT range. This bias due to HCT could be overcome by analyzing the whole spot. The method was linear (r2>0.99) within calibration range (5 to 600 nmol/L) and the lower limit of quantification was determined to be 3 nmol/L.

Conclusions & Discussion

The novel Fluispotter® DBS sampler has the potential to deliver the blood and generate DBS with variation within acceptable limits. The validated analytical method is well suited for the intended clinical studies.

The project was funded by Innovation Fund Denmark