Electrospray Ion Mobility Spectrometer Based on Flexible Printed-Circuit Board Electrodes with Improved Resolving Power.

An easily built drift tube instrument with ring electrodes made of rolled-up flexible printed circuit boards is reported. Its resolving power was maximized by careful attention to the drift tube geometry and the response time of the detector amplifier and by employing a high separation field strength. The separation of singly charged aliphatic quaternary ammonium ions introduced by electrospray was performed, and the measured resolving power was between 86 and 97% of the theoretical limit for three different drift tube lengths investigated. For the longest drift length of 30 cm, a resolving power of up to 228 was obtained. Three benzalkonium chlorides were also separated with resolving powers of over 210. The tristate injection scheme can also be used, with only a small loss of the separation performance compared to the two-state injection.

Reagent-less and sub-minute quantification of sulfite in food samples using substrate-integrated hollow waveguide gas sensors coupled to deep-UV LED.

The increasing consumption of processed foods demands the usage of chemical preservatives to ensure freshness and extended shelf life. For this purpose, sodium sulfite and its derivatives have been widely used in a variety of food products to inhibit microbial spoilage and for mitigating oxidative decay. However, the excessive consumption of sulfite may cause health problems, thus requiring rapid and accurate analytical methods for the rapid identification of threshold levels. Conventionally, sulfite is volatilized from food samples by acidification followed by trapping of the gaseous SO2 and determination using a suitable analytical technique. Herein, we propose a yet unprecedented reagent-less approach via direct absorbance measurements of gaseous SO2 at 280 nm after sample acidification. The detection system combines a deep-UV LED and a SiC photodiode with a substrate-integrated hollow waveguide (iHWG) gas cell. Absorbance measurements were performed using a log-ratio amplifier circuitry, resulting in noise levels <0.7 mAU. This innovative concept enabled the determination of sulfite in beverages in the range of 25-1000 mg L-1 with suitable linearity (r2 > 0.99) and an analysis time <30 s. The limit of detection (LOD) was calculated at 14.3 mg L-1 (3σ) with an iHWG providing an optical path length of 75 mm. As a proof of concept, this innovative analytical platform was employed for sulfite quantification in concentrated grape juice, coconut water and beer, with suitable accuracy in terms of recovery (83-117%) and favorable comparison with the official Monier-Williams method. Given the inherent modularity and adaptability of the device concept, we anticipate the application of the proposed analytical platform for the in-situ studies addressing sulfite and other volatilized preservatives in a wide variety of food products with tailorable detectability.

High voltage pulser for ion shutters in ion mobility spectrometry based on an optocoupler.

A novel high voltage pulser for an ion shutter used in drift-tube ion-mobility spectrometers is described. The simple design suitable for the in-house construction of these spectrometers relies on a special optocoupler to isolate the triggering circuitry from the high voltage at the ion shutter. The device was tested with an electrospray-ionization ion-mobility device with a 10 cm drift tube operated at 4 kV into which a standard test mixture of four tetraalkylamines was injected with a negative going gating pulse of about 50 V on top of 4 kV. A fall time of 15.7 µs and a rise time of 2.0 µs were determined for the pulse, which was adequate for the required injection pulse width of 450 µs. Resolving powers between 61 and 81 were determined for the four quaternary amines, which were found to be comparable to the performance obtained with a previously reported pulser circuitry of a different design used as a reference.

CO2-measuring dongle.

The compact pocketable CO2-measuring device is built on a small printed circuit board (PCB) with the dimensions of ca. 8.5 × 3 cm. It is plugged into the universal serial bus (USB) port of a personal computer (PC) which serves to provide power and for downloading the measurements. The measurements can be viewed on the computer display where they also can be plotted as a graph to recognize trends. As the level of CO2 rises indoors when people are present and the air is not exchanged adequately the device can be employed as a personal device for monitoring indoor air quality. This is of particular interest when airborne pathogens might be present such as during the COVID-19 pandemic. The device utilizes a novel compact CO2 sensor which has only become available commercially recently, and is based on the photoacoustic measuring principle. A graphical user interface on the PC programmed in Python allows easy interaction with the user. A MSP430FR2433 microcontroller on the board controls the sensor and establishes the communication to the software application on the computer. This was facilitated by the choice of Forth as the programming framework for the microcontroller.

Low-cost electronic circuitry for photoacoustic gas sensing.

The circuitry comprises a sine wave generator based on direct digital synthesis, a laser diode driver module, a band-pass frequency filter, a synchronous detector with phase adjustment circuitry and a low pass filter to form an analog lock-in amplifier, and an analog-to-digital converter. A 32-bit ARM microcontroller programmed with the open source Mecrisp dialect of the Forth interpreter language is used to set the frequency, and read the data from the analog-to-digital converter. The circuitry is tethered via a serial interface to a personal computer. A graphical user interface written in Phython allows easy interaction with the microcontroller by sending the appropriate Forth commands. The data acquired is visualized and stored on the personal computer for further processing. The circuitry is easy to build as it is based on through-hole devices, except for two necessary surface mount items, which, however, still can be soldered with a fine tipped soldering iron. The performance of the circuitry was demonstrated by the photoacoustic detection of NO2 using a laser diode with a wavelength of 450 nm.

Determination of tobramycin in eye drops with an open-source hardware ion mobility spectrometer.

The analysis of tobramycin was demonstrated successfully as an example for electrospray ionization on an open-source hardware ion mobility spectrometer. This instrument was assembled inexpensively in-house, and required only very few purpose-made components. The quantitative determination of tobramycin required 20 s for a reading. The calibration curve for the range from 50 to 200 µM was found to be linear with a correlation coefficient of r = 0.9994. A good reproducibility was obtained (3% relative standard deviation) and the limit of detection was determined as 8 µM. As the concentration of the active ingredient in the eye drops (ophthalmic solutions) is too high for the sensitivity of the instrument, the samples had to be diluted appropriately.

Determination of Binary Gas Mixtures by Measuring the Resonance Frequency in a Piezoelectric Tube.

The composition of gas mixtures may be determined via changes of the speed of sound. As this affects the resonance frequency of the gas inside a tube, indirect measurements through a frequency analysis are also possible. It is demonstrated that this may be carried out with unprecedented simplicity by the novel employment of a piezoelectric tube which serves at the same time as a resonance tube and as transducer into the electronic domain. Experiments were run using a simple diecast aluminum box as the measuring cell, inside which the piezoelectric tube made from lead zirconium titanate with 30-mm length and 5.35-mm inner diameter was suspended. A small loudspeaker placed into the cell served for excitation of the resonance. Peak frequencies between 3910 and 14,590 Hz (for pure CO2 and He, respectively) were obtained. Two component mixtures of O2/N2, CO2/N2, and He/N2 at various composition were tested. A linear frequency change from 4790 to 5100 Hz was observed when going from pure O2 to pure N2.

Ambient ionization source based on a dielectric barrier discharge for direct testing of pharmaceuticals using ion mobility spectrometry.

The instrument is based on a miniature plasma source mounted at an oblique angle close to the injection gate of the ion mobility spectrometer. The plasma torch consists of two 5 mm wide external cylindrical electrodes, 10 mm apart, which are placed coaxially around a fused silica tube (1.5 mm i.d. and 3.0 mm o.d.). A small helium plasma is created by applying a alternating voltage of 8 kV at 28 kHz and employed for the direct desorption and ionization of solid or liquid samples, which are placed on an electrically isolated support. The separation section of the ion mobility spectrometer has a drift tube of 10 cm length and an applied high voltage of 4 kV. The instrument was built in-house at low cost and can easily be duplicated. Its usefulness was demonstrated by the rapid identification of five different pharmaceutical drugs, namely acetaminophen, loratadine, norfloxacin, tadalafil, thiamine as well as caffeine in ground coffee beans.

Making virtual health care accessible to the deaf community: Findings from the telehealth survey.

INTRODUCTION: To reduce COVID-19 exposure risk, virtual visits became widely adopted as a common form of healthcare delivery for the general population. It is unknown how this affected the deaf population, a sociolinguistic minority group that continues to face communication and healthcare barriers. The survey's objective was to describe the deaf participants' experiences with telehealth visits. METHODS: A 28-item online survey, available in American Sign Language and English, was developed and disseminated between November 2020 and January 2021. Ninety-nine deaf participants responded. Descriptive statistics were performed to assess the participant's virtual health care use, experiences, and communication approaches. RESULTS: Seventy-five percent of respondents used telehealth at least once in the past 12 months (n = 74; age = 37.6 ± 14.5 years). Of those who used telehealth, nearly two-thirds experienced communication challenges (65.3%; n = 49). Half of the participants reported having to connect via a video relay service that employs interpreters who maintain general certification instead of a remote interpreter with specialized health care interpreting certifications for video visits with their health care providers (n = 37) and a third of participants reported needing to use their residual hearing to communicate with their providers (n = 25). CONCLUSION: Standard protocols for health care systems and providers are needed to minimize the burden of access on deaf patients and ensure virtual visits are equitable. It is recommended these visits be offered on Health Insurance Portability and Accountability Act-compliant platforms and include multi-way video to allow for the inclusion of remote medical interpreters and/or real-time captionists to ensure effective communication between the provider and the deaf patient occurs.

Using Gaze Tracking as a Research Tool in the Deaf Health Literacy and Access to Health Information Project: Protocol for a Multisite Mixed Methods Study and Preliminary Results.

BACKGROUND: Previous studies have identified the internet as a major source of health information. Reliable and accessible sources of web-based health information are critical for cultivating patient-centered care. However, the accessibility and use of web-based health information remains largely unknown for deaf individuals. We used gaze-tracking technology to understand the navigation and use of web-based health information by deaf adults who communicate with sign language and by hearing adults. OBJECTIVE: This paper discusses our protocol for implementing gaze-tracking technology in a study that included both deaf and hearing participants. We report the preliminary results and lessons learned from the implementation of the protocol. METHODS: We conducted gaze-tracking sessions with 450 deaf signers and 450 hearing participants as a part of a larger, multisite mixed methods research study. Then, we conducted qualitative elicitation interviews with a subsample of 21 deaf and 13 hearing participants, who engaged in a search task and reviewed their gaze recordings. To our knowledge, no study has implemented a similar research protocol to better understand the experiences of deaf adults. As such, we also examined research staff notes and observations from team meetings regarding the conduct of gaze-tracking data to delineate lessons learned and best practices for research protocols in this area. RESULTS: Findings from the implementation of this study protocol highlight the use of gaze technology with deaf participants. We developed additional protocol steps to minimize gaze disruption from either lipreading or communicating in sign language. For example, research assistants were often unable to maintain eye contact with participants while signing because of the need to simultaneously point at the computer monitor to provide instructions related to gaze study components, such as the calibration process. In addition to developing ways to effectively provide instructions in American Sign Language, a practice exercise was included in the gaze tracker session to familiarize participants with the computer and technology. The use of the playback feature permitted a deeper dialogue between researchers and participants, which we found vital for understanding the experiences of deaf participants. CONCLUSIONS: On the basis of our experience using the study protocol through a large research project, incorporating gaze-tracking technology offers beneficial avenues for better understanding how individuals interact with health information. Gaze tracking can determine the type and placement of visual content that attracts attention from the viewers of diverse backgrounds, including deaf individuals. The lessons learned through this study will help future researchers in determining ideal study designs, such as suitable protocols and participant characteristics (eg, deaf signers), while including gaze trackers in their projects. This approach explored how different ways of presenting health information can affect or enable visual learners to engage and use health information effectively. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): RR1-10.2196/26708.

Compact automated capillary electrophoresis instrument for coupling with mass spectrometry by using sheathless electrospray ionization.

The low-cost set-up is based on the flexible microfluidic breadboard approach. To avoid the use of electrically driven devices at the high voltage injection end of the capillary pneumatically actuated pumps and valves are employed. It is coupled to the mass spectrometer with a sheathless electrospray obtained in an electrodeless interface configuration. This simplification is achieved by carrying out the analysis in two distinct steps, firstly the separation without the formation of an electrospray, and secondly detection in which the electrospray is created while pumping out the content of the capillary. The performance of the instrument was tested by analysing three benzalkonium ions and the four pesticides pyrifenox, pirimicarb, cyprodinil and pyrimethanil. Detection limits between 0.36 and 0.76 µM and peak reproducibilities between 5.2% and 6.6% (50 µM standards) were obtained for the latter.

The Deaf Community's Experiences Navigating COVID-19 Pandemic Information.

BACKGROUND: Users of American Sign Language (ASL) who are deaf often face barriers receiving health information, contributing to significant gaps in health knowledge and health literacy. To reduce the spread of coronavirus disease 2019 (COVID-19) and its risk to the public, the government and health care providers have encouraged social distancing, use of face masks, hand hygiene, and quarantines. Unfortunately, COVID-19 information has rarely been available in ASL, which puts the deaf community at a disadvantage for accessing reliable COVID-19 information. OBJECTIVE: This study's primary objective was to compare COVID-19-related information access between participants who are deaf and participants who are hearing. METHODS: The study included 104 adults who are deaf and 74 adults who are hearing who had participated in a prior health literacy study. Surveys were conducted between April and July 2020 via video conference, smartphone apps, or phone calls. COVID-19 data were linked with preexisting data on demographic and health literacy data as measured by the Newest Vital Sign (NVS) and the ASL-NVS. KEY RESULTS: Neither group of participants differed in their ability to identify COVID-19 symptoms. Adults who are deaf were 4.7 times more likely to report difficulty accessing COVID-19 information (p = .011), yet reported using more preventive strategies overall. Simultaneously, adults who are deaf had 60% lower odds of staying home and calling their doctor versus seeking health care immediately or doing something else compared with participants who are hearing if they suspected that they had COVID-19 (p = .020). CONCLUSIONS: Additional education on recommended COVID-19 management and guidance on accessible health care navigation strategies are needed for the deaf community and health care providers. Public health officials should ensure that public service announcements are accessible to all audiences and should connect with trusted agents within the deaf community to help disseminate health information online in ASL through their social media channels. [HLRP: Health Literacy Research and Practice. 2021;5(2):e162-e170.] Plain Language Summary: Compared to participants who are hearing, a higher portion of participants who are deaf reported challenges with accessing, understanding, and trusting COVID-19 information. Although respondents who are deaf had similar knowledge of symptoms compared to participants who are hearing, they used more prevention strategies and were more likely to plan immediate care for suspected symptoms. Improved guidance on COVID-19 management and health care navigation accessible to the deaf community is needed.

Development of simple drift tube design for ion mobility spectrometry based on flexible printed circuit board material.

A study on the use of flexible printed circuit board material for the construction of drift tubes for ion mobility spectrometry is reported. This is significantly less complicated than the conventional approach based on stacked electrode and insulator rings, as the material can simply be rolled up to obtain a string of circular electrodes. The size and spacing of the electrodes was found to have a strong effect on the resolving power. For an optimized geometry with electrodes of 1.5 mm width at a pitch of 3.5 mm resolving powers of up to 80 were achieved for quaternary amines introduced by electrospray ionization into a drift tube of 10 cm length and an applied voltage of 4200 V. This performance was found to be comparable to that of a conventional drift tube based on stacked rings with otherwise identical geometry and operating conditions. The entire instrument was constructed in-house. Its utility was demonstrated with the determination of the C12, C14 and C16 benzalkonium ions in several commercial cleaning products with limits of detection of 20, 25, and 38 µg L-1, respectively.

Methionine oxidation of proteins analyzed by affinity capillary electrophoresis in presence of silver(I) and gold(III) ions.

Oxidative damage of biopharmaceuticals during manufacturing and storage is a key concern throughout pharmaceutical development. However, few simple and robust analytical methods are available for the determination of oxidation sites. Here, the potential of affinity capillary electrophoresis (ACE) in the separation of proteins with oxidized methionine (Met) residues is shown. Silver(I) and gold(I) ions have the attribute to selectively form complexes with thioethers over sulfoxides. The addition of these ions to the BGE leads to a selective complexation of Met residues and, thus, to a change of charge allowing separation of species according to the different oxidation states of Met. The mechanisms of these interactions are discussed and binding constants for peptides containing Met with silver(I) are calculated. Additionally, the proposed method can be used as an indicator of oxidative stress in large proteins. The presented technique is easily accessible, economical, and has rapid analysis times, adding new approaches to the analytical toolbox of Met sulfoxide detection.

Piezoelectric tube as resonant transducer for gas-phase photoacoustics.

The use of a piezoelectric tube for the photoacoustic gas-phase determination of NO2 as a model analyte is demonstrated. The tube is made from lead zirconate titanate with 30 mm length and 5.35 mm internal diameter. Its inner and outer surfaces are coated with electrodes. The tube serves as both, resonance body and transducer. The design is thus simpler than the usual combination of resonance tube and microphone as the two functions are embodied in the same component. The main resonance frequency of the tube was found to be 5341 Hz. A blue laser diode emitting at 450 nm was employed as light source for the determination of NO2. The limit of detection was determined as 83 ppbV and the calibration curve was linear with a coefficient of determination (r2) of 0.9998 up to the highest concentration of 15 ppmV tested.

Photoacoustic detection of ozone with a red laser diode.

The photoacoustic detection of ozone using the Chappuis band is demonstrated. A visible red laser diode emitting at 638 nm was employed as a light source. The photoacoustic cell consisted of a conventional resonance tube with a MEMS (microelectromechanical systems) microphone placed outside an opening along the tube. A calibration curve for the range from 33 ppmV to 215 ppmV was found to be highly linear with a coefficient of determination (r2) of 0.9999, when allowing for different measurement frequencies to account for shifts in the speed of sound due to changes in the gas matrix. The limit of detection was found to be 1.6 ppmV for an optical power of the laser diode of about 130 mW.

Modular instrumentation for capillary electrophoresis with laser induced fluorescence detection using plug-and-play microfluidic, electrophoretic and optic modules.

This study reports on the development of a novel instrument for capillary electrophoresis (CE) coupled with laser induced fluorescence (LIF) detection that is inspired by the Lego-toy concept. The Lego CE-LIF design is an evolution of purpose-made CE instrumentation, allowing the users to construct their own analytical device with a high degree of standardization (i.e. a "standard" setup) without requirement of mechanical and electronic workshop facilities. To allow instrument reproduction outside the original fabrication laboratory, which is not trivial for in-house-built CE systems, the new design is based on unprecedent 'plugging' hyphenation of various off-the-shelf parts available for microfluidics, optics and electrophoresis. To render the operation with Lego CE-LIF optimal, we developed a new background electrolyte (BGE), using for the first time extremely high concentrations of zwitterionic and large weakly charged species for much improvement of detection sensitivity. The Lego CE-LIF was demonstrated for separation and detection of oligosaccharides labelled with 8-aminopyrene-1,3,6-trisulfonic acid (APTS). The new gel-free BGE for oligosaccharide analysis also allowed simplification of the conventional CE-LIF protocol used with commercial instruments while keeping satisfactory separation performances. Furthermore, the new BGE is fully compatible with a non-thermostatted Lego CE instrument thanks to low current and therefore low heat generation under application of a high voltage.

Capacitively coupled contactless conductivity detection for analytical techniques - Developments from 2018 to 2020.

The developments of analytical contactless conductivity measurements based on capacitive coupling over the two years from mid-2018 to mid-2020 are covered. This mostly concerns applications of the technique in zone electrophoresis employing conventional capillaries and to a lesser extent lab-on-chip devices. However, its use for the detection in several other flow-based analytical methods has also been reported. Detection of bubbles and measurements of flow rates in two-phase flows are also recurring themes. A few new applications in stagnant aqueous samples, e.g. endpoint detection in titrations and measurement on paper-based devices, have been reported. Some variations of the design of the measuring cells and their read-out electronics have also been described.

Low-cost automated capillary electrophoresis instrument assembled from commercially available parts.

A CE instrument that can be assembled from commercially available components with minimal construction effort is described. Except for the electronic control circuitry no specially made parts are required. It is based on a flexible design of microfluidic, electropneumatic, and electronic sections and different configurations can easily be implemented. Automated injection into the capillary is performed hydrodynamically by the application of a pressure for a controlled length of time. The performance of the device was tested with a contactless conductivity detector by separating different metal ions. In addition, nine metal cations related to the quality of honey were separated in 2.3 min and four honey samples were analysed quantitatively to demonstrate the applicability of the method.

Low-cost and versatile analytical tool with purpose-made capillary electrophoresis coupled to contactless conductivity detection: Application to antibiotics quality control in Vietnam.

In this study, the development of our purpose-made capacitively coupled contactless conductivity detection (C4 D) for CE is reported. These systems have been employed as a simple, versatile, and cost-effective analytical tool. CE-C4 D devices, whose principle is based on the control of the ion movements under an electrical field, can be constructed even with a modest financial budget and limited infrastructure. A featured application was developed for quality control of antimicrobial drugs using CE-C4 D, with most recent work on determination of aminoglycoside and glycopeptide antibiotics being communicated. For aminoglycosides, the development of CE-C4 D methods was adapted to two categories. The first one includes drugs (liquid or powder form) for intravenous injection, containing either amikacin, streptomycin, kanamycin A, or kanamycin B. The second one covers drugs for eye drops (liquid or ointment form), containing either neomycin, tobramycin, or polymyxin. The CE-C4 D method development was also made for determination of some popular glycopeptide antibiotics in Vietnam, including vancomycin and teicoplanin. The best detection limit achieved using the developed CE-C4 D methods was 0.5 mg/L. Good agreement between results from CE-C4 D and the confirmation method (HPLC- Photometric Diode Array ) was achieved, with their result deviations less than 8% and 13% for aminoglycoside and glycopeptide antibiotics, respectively.