Measurement of CO2 in Water from an Ultraviolet Oxidizer for a Space-Worthy Wastewater Recovery System Using Raman Spectroscopy.

NASA has been developing and testing a water recovery system for over two decades to minimize the amount of water required for long duration human space missions. A key system component is the total organic carbon analyzer (TOCA) that determines if the recovered water is below the toxicology-defined health limit of 5 mg/L TOC and is safe to drink. The TOCA is composed of a liquid phase loop and a gas phase loop. The TOCA employs an oxidizer to convert the organics in the liquid phase to carbon dioxide (CO2) and a liquid-gas separator to isolate the CO2 for measurement in the gas phase by infrared spectroscopy. In an effort to reduce the consumables, mass, volume, and power of the system, we investigated the ability of surface-enhanced Raman spectroscopy (SERS), and Raman spectroscopy to measure 5 mg/L carbon in water. The SERS measurement employed silver colloids to increase sensitivity, while the Raman measurements used multiple mirrors to increase sensitivity. Here, we present SERS measurements of carbonate (CO3=) at 3 mg/L carbon and Raman measurements of CO2 at 9 mg/L carbon in the effluent water of a new oxidizer being developed for a future TOCA. Both SERS and Raman techniques can determine TOC in the liquid phase, eliminating the need for the gas phase loop and associated supplies and replacement components, which could effectively decrease the size and weight of the current TOCA by as much as 50%.

Drug Content Uniformity: Quantifying Loratadine in Tablets Using a Created Raman Excipient Spectrum.

Raman spectroscopy has proven valuable for determining the composition of manufactured drug products, as well as identifying counterfeit drugs. Here we present a simple method to determine the active pharmaceutical ingredient (API) mass percent in a sample that does not require knowledge of the identities or relative mass percents of the inactive pharmaceutical ingredients (excipients). And further, we demonstrated the ability of the method to pass or fail a manufactured drug product batch based on a calculated acceptance value in accordance with the US Pharmacopeia method for content uniformity. The method was developed by fitting the Raman spectra of 30 Claritin® tablets with weighted percentages of the Raman spectrum of its API, loratadine, and a composite spectrum of the known excipients. The mean loratadine mass of 9.79 ± 40 mg per 100 mg tablet compared favorably to the 10.21 ± 0.63 mg per 100 mg tablet determined using high-performance liquid chromatography, both of which met the acceptance value to pass the 10 mg API product as labelled. The method was then applied to a generic version of the Claritin product that employed different excipients of unknown mass percents. A Raman spectrum representative of all excipients was created by subtracting the API Raman spectrum from the product spectrum. The Raman spectra of the 30 generic tablets were then fit with weighted percents of the pure loratadine spectrum and the created excipient spectrum, and used to determine a mean API mass for the tablets of 10.12 ± 40 mg, again meeting the acceptance value for the 10 mg API product. The data suggest that this simple method could be used to pass or fail manufactured drug product batches in accordance with the US Pharmacopeia method for content uniformity, without knowledge of the excipients.

A Surface-Enhanced Raman Spectral Library of Important Drugs Associated With Point-of-Care and Field Applications.

During the past decade, the ability of surface-enhanced Raman spectroscopy (SERS) to measure extremely low concentrations, such as mg/L and below, and the availability of hand-held Raman spectrometers, has led to a significant growth in the number and variety of applications of SERS to real-world problems. Most of these applications involve the measurement of drugs, such as quantifying medication in patients, identifying illicit drugs in impaired drivers, and more recently, identifying drugs used as weapons. Similar to Raman spectroscopy, most of the point-of-care and field applications involve the identification of the drug to determine the course of action. However, unlike Raman spectroscopy, spectral libraries are not readily available to perform the necessary identification. In a large part, this is due to the uniqueness of the commercially available SERS substrates, each of which can produce different spectra for the same drug. In an effort to overcome this limitation, we have measured numerous drugs using the most common, and readily available SERS material and hand-held Raman analyzers, specifically gold colloids and analyzers using 785 nm laser excitation. Here we present the spectra of some 39 drugs of current interest, such as buprenorphine, delta-9 tetrahydrocannabinol, and fentanyl, which we hope will aid in the development of current and future SERS drug analysis applications.

Detection of codeine and fentanyl in saliva, blood plasma and whole blood in 5-minutes using a SERS flow-separation strip.

A simple-to-use device to measure drugs in saliva, blood plasma, and whole blood for point-of-care analysis and treatment of overdose patients has been investigated. A rudimentary flow strip has been developed to separate opioids from these biofluids for analysis by surface-enhanced Raman spectroscopy (SERS). The strips are based on lateral flow assays, in which the antibodies have been substituted by SERS-active pads for detection. Samples of codeine and fentanyl, artificially added to these biofluids, were measured using the strips by a field-usable Raman spectrometer. We report measurement of these drugs in these biofluids from 0.5 to 5 µg mL-1 in 5 minutes. Calculated limits of detection for the spectra suggest that these drugs could be measured at 5 to 20 ng mL-1 with improvements in the strips' separation capability.

Quantitative Measurements of Codeine and Fentanyl on a Surface-Enhanced Raman-Active Pad Test.

The USA is in the midst of an opioid crisis that included over 60,000 overdose fatalities in 2017, mostly unintentional. This is due to excessive use of prescription opioids and the use of very strong synthetic opioids, such as fentanyl, mixed with illicit street drugs. The ability to rapidly determine if people or packages entering the country have or contain drugs could reduce their availability, and thereby decrease the use of illicit drugs. In an effort to address this problem, we have been investigating the ability of surface-enhanced Raman spectroscopy to detect trace amounts of opioids on clothing and packages. Here, we report the measurement of codeine and fentanyl at 100 ng/mL for 5 min on a pad impregnated with gold colloids, as well as a preliminary measurement of 500 pg of fentanyl on a glass surface using one of these pads. The calculated limit of detection for this measurement was 40 pg. This data strongly suggests that these pads, used with portable Raman analyzers, would be invaluable to airport security, drug raids, crime scenes, and forensic analysis.

Analysis of Twenty-Two Performance Properties of Diesel, Gasoline, and Jet Fuels Using a Field-Portable Near-Infrared (NIR) Analyzer.

The change in custody of fuel shipments at depots, pipelines, and ports could benefit from an analyzer that could rapidly verify that properties are within specifications. To meet this need, the design requirements for a fuel analyzer based on near-infrared (NIR) spectroscopy, such as spectral region and resolution, were examined. It was found that the 1000 to 1600 nm region, containing the second CH overtone and combination vibrational modes of hydrocarbons, provided the best near-infrared to fuel property correlations when path length was taken into account, whereas 4 cm(-1) resolution provided only a modest improvement compared to 16 cm(-1) resolution when four or more latent variables were used. Based on these results, a field-portable near-infrared fuel analyzer was built that employed an incandescent light source, sample compartment optics to hold 2 mL glass sample vials with ∼1 cm path length, a transmission grating, and a 256 channel InGaAs detector that measured the above stated wavelength range with 5-6 nm (∼32 cm(-1)) resolution. The analyzer produced high signal-to-noise ratio (SNR) spectra of samples in 5 s. Twenty-two property correlation models were developed for diesel, gasoline, and jet fuels with root mean squared error of correlation - cross-validated values that compared favorably to corresponding ASTM reproducibility values. The standard deviations of predicted properties for repeat measurements at 4, 24, and 38℃ were often better than ASTM documented repeatability values. The analyzer and diesel property models were tested by measuring seven diesel samples at a local ASTM certification laboratory. The standard deviations between the analyzer determined values and the ASTM measured values for these samples were generally better than the model root mean squared error of correlation-cross-validated values for each property.

Drug stability analysis by Raman spectroscopy.

Pharmaceutical drugs are available to astronauts to help them overcome the deleterious effects of weightlessness, sickness and injuries. Unfortunately, recent studies have shown that some of the drugs currently used may degrade more rapidly in space, losing their potency before their expiration dates. To complicate matters, the degradation products of some drugs can be toxic. Here, we present a preliminary investigation of the ability of Raman spectroscopy to quantify mixtures of four drugs; acetaminophen, azithromycin, epinephrine, and lidocaine, with their primary degradation products. The Raman spectra for the mixtures were replicated by adding the pure spectra of the drug and its degradant to determine the relative percent contributions using classical least squares. This multivariate approach allowed determining concentrations in ~10 min with a limit of detection of ~4% of the degradant. These results suggest that a Raman analyzer could be used to assess drug potency, nondestructively, at the time of use to ensure crewmember safety.

Raman spectroscopy using 1550 nm (retina-safe) laser excitation.

During the past decade, the use of portable Raman analyzers for field measurements has grown dramatically. However, most analyzers use 785 nm excitation lasers that can cause permanent eye damage. To overcome this safety concern, we have built a portable Fourier transform (FT) Raman analyzer using a 1550 nm retina-safe excitation laser and have compared its performance to our 1064 nm FT-Raman analyzer, which uses the same optical design. Raman theory predicts approximately five times lower peak intensities at 1550 nm. Although we found that intensities were as much as 20 times less intense, the analyzer is still capable of measuring spectra of sufficient quality to identify and differentiate chemicals.

[Employment supports: Perceptions of people with severe mental disorders]. / Les soutiens associés au maintien en emploi: perceptions des personnes aux prises avec un trouble mental grave.

Professional rehabilitation of people with severe mental illness is a field of research often left aside. Despite the aspiration of people with severe mental illness to employment, their presence in the job market remains low. Lack of supports appears to be one explanation. Thus, the aim of this study was to identify the types of necessary supports to maintain these people in employment. Six (6) participants have been recruited following a qualitative methodology. Ten types of supports have been identified and classified according to their direct association to work or to the residential or community environment. To conclude, the authors suggest a greater involvement from mental health workers in the identification and development of supports that favour maintaining these people in employment.