Immunosuppressant drug monitor: A non-invasive device to measure tacrolimus level in the saliva of transplanted patients.

Solid organ and vascularized composite allograft transplantation are pivotal in enhancing both life expectancy and quality of life. However, the significant risk of donor tissue rejection requires lifelong immunosuppressive therapy. Tacrolimus, a common component of immunosuppressive regimens, offers effectiveness in preventing organ rejection but poses challenges due to its narrow therapeutic window and toxicity, making it essential to carefully monitor its concentration. Tacrolimus trough levels are currently measured in blood, requiring frequent blood draws from patients, and results are available after 3 to 6 h. To address the need for a fast, minimally-invasive, and simple method to monitor tacrolimus concentrations, we have assessed a new device for at-home analysis, the Immunosuppressant Drug Monitor (IDM) that can extract, identify and quantify tacrolimus in saliva within 15 min. We included males and females hospitalized at Massachusetts General Hospital Transplant Unit, between the ages of 21 and 65 years, and treated with Tacrolimus. Informed consent, demographic and treatment data were collected. Each subject was asked to provide a 5 mL saliva sample that was de-identified and processed by the IDM, while a 5 mL blood sample was drawn and supplied to the MGH clinical lab for analysis by the current standard, immunoassays. The predicted tacrolimus concentration found in saliva was compared to the blood trough level results. 62 samples from 31 different patients were obtained. The male to female ratio and ethnicity distribution were well balanced. The majority of patients were within 30 days of initiating tacrolimus treatment. After IDM calibration and exclusion, 21 samples were measured by the IDM. Using an exponential function fit, the IDM showed a correlation of R2 = 0.39 between the saliva Test Line absorption and the measured tacrolimus concentration in blood, with an average absolute error of 1.8 ng/mL. Our results demonstrate a clear correlation between blood and saliva measurements. The IDM provided promising results to monitor immunosuppressant drug concentrations in patients after transplantation. Future larger studies will further develop the correlation, and the IDM's potential impact on patient outcomes.

Analysis of Drugs in Saliva of US Military Veterans Treated for Substance Use Disorders Using Supported Liquid Extraction and Surface-Enhanced Raman Spectral Analysis.

According to the Center for Disease Control, there were more than 107,000 US drug overdose deaths in 2021, over 80,000 of which due to opioids. One of the more vulnerable populations is US military veterans. Nearly 250,000 military veterans suffer from substance-related disorders (SRD). For those seeking treatment, buprenorphine is prescribed to help treat opioid use disorder (OUD). Urinalysis is currently used to monitor buprenorphine adherence as well as to detect illicit drug use during treatment. Sometimes sample tampering occurs if patients seek to generate a false positive buprenorphine urine test or mask illicit drugs, both of which can compromise treatment. To address this problem, we have been developing a point-of-care (POC) analyzer that can rapidly measure both medications used for treatment and illicit drugs in patient saliva, ideally in the physi-cian's office. The two-step analyzer employs (1) supported liquid extraction (SLE) to isolate the drugs from the saliva and (2) surface-enhanced Raman spectroscopy (SERS) to detect the drugs. A prototype SLE-SERS-POC analyzer was used to quantify buprenorphine at ng/mL concentrations and identify illicit drugs in less than 1 mL of saliva collected from 20 SRD veterans in less than 20 min. It correctly detected buprenorphine in 19 of 20 samples (18 true positives, 1 true negative and 1 false negative). It also identified 10 other drugs in patient samples: acetaminophen, amphetamine, cannabidiol, cocaethylene, codeine, ibuprofen, methamphetamine, methadone, nicotine, and norbuprenorphine. The prototype analyzer shows evidence of accuracy in measuring treatment medications and relapse to drug use. Further study and development of the system is warranted.

Degenerative Cervical Spondylosis: A Cause of Vertigo?

STUDY DESIGN: Prospective observational study. OBJECTIVES: Studying the effect of degenerative cervical spondylosis(CS) on blood flow velocity of vertebral artery (VA) during cervical spine rotation in different head positions and its association with vertigo. INTRODUCTION: Vertigo is one of the most common complaints seen in an out-patient clinic. Its association with CS remains an enigma for a treating physician. This study planned to systematically analyze the association between vertigo and CS by evaluating VA blood flow dynamics in different head positions. METHODS: 100 patients with ages ranging from 20-80 years were recruited. First group of 50 patients with CS with vertigo were compared with second study group of 50 patients having CS without vertigo. Cervical radiographs were used to evaluate CS using cervical degenerative index (CDI). Color doppler was used to measure VA blood flow with head in neutral position and 60° lateral rotation with 30° extension. Same procedure was repeated on opposite side. Measurements performed included peak systolic blood flow velocity(PSV) and end diastolic blood flow velocity (EDV). RESULTS: Among patients with CS, patients having vertigo showed significantly more evident degenerative changes (CDI ≥25) (P=<0.001). High grade CS patients (CDI ≥25) with vertigo had statistically significant lower blood flow parameters with head rotation in the left and right VAs as compared to CS patients without vertigo. CONCLUSION: This study highlights important pathophysiological mechanism of vertigo observed in patients of CS. The magnitude of reduction in VA blood flow was significantly higher in patients with advanced CS presenting as vertigo.

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%.

Pharyngocutaneous Fistula and Horner's Syndrome following Loosening of Locking Screw of Anterior Cervical Plating: A Rare Case Report and Management.

We hereby present a rare case of pharyngocutaneous fistula associated with locking screw loosening causing internal cricopharynx perforation and Horner's syndrome following anterior cervical plating. A 27-year-old male patient had undergone anterior cervical plating at C5-C7 level due to gunshot injury to the neck, and 1 month postsurgery, he developed fistula in the neck showing discharge of consumed food contents. He presented to us 1 year postsurgery with the discharging fistula, left upper-limb weakness, and Horner's syndrome that developed after surgery. The previously unexplored right side was used to remove implant, and owing to solid union at corpectomy, no additional fixation was performed. Intraoperatively, pharyngeal wall dehiscence was observed. Attempt of removal of impinged screw was abandoned since it migrated into the esophagus. Serial abdomen radiographs revealed successive passage of screw through the gastrointestinal (GI) tract until it could not be visualized. As the patient showed reduced discharge, a GI surgeon gave a conservative trial with nasogastric intubation. Currently, fistula is showing minimal discharge with no food. Having knowledge of this possible rare outcome and awareness of various multidisciplinary approaches for management makes practicing spine surgeon equipped to handle such undesirable complications.

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.

Severe Kyphotic Deformity Involving Thoracolumbar Region -A Management Dilemma.

Introduction: Thoracolumbar kyphosis is common cause of sagittal spinal malalignment. Neglected tuberculous infection in childhood often presents as kyphotic deformity in adulthood, especially in India, where tuberculosis is endemic. Complete clinical and radiological evaluation is necessary to decide need for surgical intervention. We came across this case of severe thoracolumbar kyphosis extending into lower lumbar spine due to block vertebra formation from fusion of T12 to L4 vertebrae. Case Report: The patient presented with debilitating mechanical low back pain without any neurological abnormality in lower limb. The patient was treated surgically with posterior corrective three-column osteotomy and fixation in view of the persistent mechanical low back pain. At 1-year follow-up, the patient showed significant improvement in low back disability score. Conclusion: After performing three-column osteotomy, we obtained 63% correction in thoracolumbar kyphosis resulting in relief of symptomatic severe axial low back pain and ambulatory capacity with Oswestry Disability Score of 10%. This case highlights long-term natural history of neglected post-tuberculous affection of thoracolumbar region of vertebral column and management challenges of severe thoracolumbar kyphosis.

Incidence and Outcome Analysis of Vertebral Artery Injury in Posttraumatic Cervical Spine.

OBJECTIVE: Vertebral artery injury (VAI) after cervical spine trauma often remains undiagnosed. Despite various clinical studies suggesting simultaneous occurrence of VAI with cervical spine trauma, guidelines regarding screening and management of posttraumatic VAI are yet to be formulated. The primary objective of the current study was to formulate a low-cost screening protocol for posttraumatic VAI, thereby reducing the incidence of missed VAI in developing countries. MATERIALS AND METHODS: This was a single-center prospective study performed on 61 patients using plain magnetic resonance imaging (MRI) as a screening tool to assess the frequency of VAI and routine X-ray to detect morphological fracture patterns associated with the VAI in posttraumatic cervical spine cases. If the MRI study showed any evidence of vascular disruption, then further investigation in the form of computed tomography angiography was done to confirm the diagnosis. RESULTS: This study showed the incidence of VAI was 14.75% (9/61). Of 61 patients, 16 had supraaxial, and 45 patients sustained subaxial cervical spine fractures. In the cohort of nine cases of VAI, eight patients had subaxial cervical spine injuries, of which seven were due to flexion-distraction injury. C5-C6 flexion-distraction injury was most commonly associated with VAI (4 cases). Of the nine cases, five succumbed to injury (mortality 55.55%), and 19 patients from the non-VAI group succumbed to injury (mortality 36.53%). From surviving four cases with VAI, two had improvement in the American Spinal Injury Association scale by Grade 1. CONCLUSION: VAI in cervical spine trauma is an underrecognized phenomenon. Plain MRI axial imaging sequence can be an instrumental low-cost screening tool in resource-deficient parts of the world. VAI has tendency to occur with high-velocity trauma like bi-facetal dislocation, which has a high mortality and poor neurological recovery.

Prevalence of Vitamin D Deficiency Amongst Indian Orthopaedic Surgeons.

BACKGROUND: Vitamin D deficiency is a widely prevalent condition with patients in both symptomatic and asymptomatic spectrum. With the lack of routine screening there exists an unknown population of Indian Orthopaedic surgeons who are deficient in Vitamin D and lead to an unexplained loss of quality of work and increased susceptibility to various other diseases. The easiest access to resources for supplementation is available to this group of treating physicians however its use for their personal cure is rarely recognised. This study aims to highlight this endemic disease and to find out its correlation with other parameters. METHODS: It is a prospective observational study including 150 practicing orthopaedic surgeons from entire India who visited our centre during 3 months duration for various educational meetings. Venous sample was collected after due informed consent and analysed at a single laboratory for 25-OH Cholecalciferol levels by a chemiluminescent assay. All the samples were analysed and a questionnaire was sent to the participants via google forms regarding various parameters under study. RESULTS: The mean serum Vitamin D levels were 18.6 ± 9.67 ng/ml in the sample studied. 17 out of 150 participants (11.3%) were found to have sufficient serum levels of 25(OH) Cholecalciferol. 105 participants (70%) were having deficient levels and 28 (18.7%) had insufficient levels of Vitamin D. Overall 88.7% participants had Vitamin D deficiency among the sample studied. CONCLUSION: This widespread prevalence of Vitamin D deficiency warrants frequent screening and routine supplementation of Vitamin D in orthopaedic surgeons thereby providing a low cost solution to improve the troublesome situation among healthcare providers.

Golden Wires and Rectangle: A Cost-Effective Treatment for Tuberculosis of the Thoracic Spine.

STUDY DESIGN: This was a retrospective study. PURPOSE: The purpose of this study was to compare the functional outcome and cost of surgery for tuberculosis (TB) of the thoracic spine between two commonly used fixation modalities "pedicular screws and rods" and "Hartshill loop rectangle and sublaminar wires." OVERVIEW OF LITERATURE: TB is a common ailment in Asia. Surgical indications have remained almost unchanged since the middle-path regimen was advocated by Tuli. Pedicle screws and Hartshill loop rectangle with sublaminar wires are the two common fixation techniques used. MATERIALS AND METHODS: This retrospective observational study was performed at a single tertiary center. Patients were divided into two groups depending on the method of fixation (pedicle screw rod/Hartshill loop rectangle and sublaminar wires). All patients were evaluated preoperatively by X-rays and magnetic resonance imaging. Patients were assessed clinically by preoperative and postoperative neurology and Visual Analog Scale score and radiologically assessed by the K angle. These variables were separately compared in both the groups. RESULTS: The functional outcomes of Hartshill loop rectangle and sublaminar wire fixation and that of pedicular screw fixation were comparable. Hartshill loop rectangle and sublaminar wire fixation was found to be more cost-effective. CONCLUSION: Hartshill loop rectangle and sublaminar wire fixation gets purchase over the posterior column structures alone when compared to pedicle screws which have a 3-column hold. However, when combined with meticulous neural decompression and skillful preparation of osteogenic bed with autologous strut grafting and additional onlay grafting, it gives overall adequate stabilization of the column with functional outcome comparable to pedicular screw and rod fixation with additional benefit of cost-effectiveness. Although Hartshill loop rectangle and sublaminar wire fixation is less commonly used now, it has a special place in the management of TB, especially in a resource-poor setting like some countries of Asia.

Dysplasia and anomalies of atlas result in pediatric torticollis: A case report and literature review.

BACKGROUND: Often, the cause of bony torticollis is difficult to determine, especially in cases of multiple craniovertebral junction anomalies. CASE DESCRIPTION: We report a rare case of a dysplastic C1 vertebra (assimilation to the right occiput and C2, a nonseparated left odontoid, and discontinuity in both anterior and posterior arches of the atlas) in a 6-year-old child with progressive torticollis. Notably, the mechanism of torticollis was not a rotatory subluxation of C1-C2, but differential growth between C1-C2. The child underwent a successful C1-C2 Goel and Harms fusion with reduction/correction of the torticollis. CONCLUSION: Torticollis caused by differential growth between the C1 and C2 vertebrae resulting in a nonrotatory subluxation/torticollis in a 6-year-old child, was successfully managed with a C1-C2 Goel and Harm's fusion.

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.

Role of Additional Coronal Magnetic Resonance Imaging in Decompression and Reconstruction with or without Segment Salvage in Thoracic Spine Tuberculosis.

STUDY DESIGN: Retrospective and observational study. PURPOSE: The present study aimed to develop guidelines for segment salvage or sacrifice based on the amount and status of the remnant portion of the vertebra as assessed by coronal magnetic resonance imaging (MRI) in addition to sagittal and axial images in thoracic spine tuberculosis (TB). OVERVIEW OF LITERATURE: Indications for surgery have not changed significantly since the 'middle path regimen' was proposed by Tuli. Goals of modern surgical management of spinal TB include debridement of diseased vertebrae, spinal cord decompression, deformity correction, and spine stabilization. However, the extent of decompression has not been defined previously. Too less decompression will lead to compromised neurological recovery, whereas large extent of decompression is associated with increased surgical morbidity and longer segment to reconstruct. METHODS: Sixty-five patients with thoracic spine TB were divided into two groups (segment salvage/sacrifice) based on the thickness of the subchondral bone and endplate morphology of the vertebra as seen on MRI. The operative procedure in the form of instrumentation with Hartshill loop rectangle and sublaminar wire using the simultaneous anterior posterior approach in lateral position (versatile approach) was performed. The patients were analyzed for postoperative fusion, improvement in kyphosis angle, and followed up for development of complications. RESULTS: This method of deciding the level of fixation and segment salvage based on coronal MRI in addition to the sagittal and axial images provided good result in 64 of 65 patients, except for one patient in the segment sacrifice group who had graft buckling and resultant kyphosis. CONCLUSIONS: For segment salvage, having a clear three-dimensional idea about the viable remnant bone is important. Viable salvaged segment reduces the morbidity of the procedure, length of the construct, and unnecessary debridement without compromising on the neural recovery and fusion rate. Hence, additional cone down coronal cuts must be required when MRI is suggestive for spinal TB because it will help in the decision making.

Does Mesh Cage Subsidence Have any Effect on Functional Outcome in Spinal Tuberculosis?

INTRODUCTION: Occurrence of mesh cage subsidence in patients undergoing anterior column reconstruction following Tuberculosis spine is frequent radiological finding as bone quality of affected vertebrae is poor. This study aims at determining effect of mesh cage subsidence on functional outcome. METHODS: Retrospective demographics of 30 patients of consecutive series in age range 4-60 year were collected with Clinical outcome evaluation using VAS, ODI and ASIA scale. 30 patient having Dorsolumbar tuberculosis with vertebral involvement ranging from 1-6 with mean vertebral level involvement of 2.71, underwent anterior column reconstruction through posterior only approach between 2011-15 were reviewed. Patients were followed at regular intervals of 6 weeks, 12 weeks, 6 months & thereafter on yearly basis. They were evaluated for interbody height loss with subsidence, fusion & segmental angle. RESULTS: Clinical parameters i.e. VAS & ODI showed improvement in postoperative period which continued to remain same even after subsidence (P < 0.05). Subsidence was categorized as combined anterior + posterior < 5mm; 5 -10mm; >10mm. ODI at follow up was 8.5 ±4.62, 9 ± 2 and 9 ± 4.2 (P = 0.961) respectively & VAS score in above group was 1.3 ± 0.51, 1.5 ± 1.2 & 1.5 ± 0.7 (P = 0.975) respectively. Subsidence was age, spinal level nonspecific. CONCLUSION: Study indicates that though Cage subsidence occurs to varying severity due to weakened vertebral bodies, it did not have significant impact on functional outcome in terms of VAS, ODI or radiological evidence of fusion following reconstruction in Spinal tuberculosis.

Rapid Identification of Buprenorphine in Patient Saliva.

Buprenorphine is becoming the medication of choice to help patients withdraw from opioid addiction. However, treatment is compromised by the inability of physicians to assess patient usage during scheduled examinations. Here we describe the development of a point-of-care (POC) analyzer that can rapidly measure both illicit and treatment drugs in patient saliva, ideally in the physician's office, and with a degree of accuracy similar to chromatography. The analyzer employs a relatively simple supported liquid extraction to isolate the drugs from the saliva and surface-enhanced Raman spectroscopy (SERS) to detect the drugs. The SERS-based POC analyzer was used to identify buprenorphine and opioids in saliva samples by matching library spectra to samples collected from 7 veterans. The total analysis time, including sample preparation, was ~25 minutes. Buprenorphine concentration was estimated between 0 and 3 µg/mL. While no other prescription opioids were detected in any samples, heroin was identified in one sample; Δ-9 tetrahydrocannabinol (THC) was detected in 3 samples; and acetaminophen, caffeine, and nicotine were detected in several samples, none of which interfered with the measurements. The analysis was in very good agreement with urinalysis, correctly identifying the presence or absence of buprenorphine and THC in 13 of 14 measurements.

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.

Rapid Analysis of Cocaine in Saliva by Surface-Enhanced Raman Spectroscopy.

Increases in illicit drug use and the number of emergency-room visits attributable to drug misuse or abuse highlight the need for an efficient, reliable method to detect drugs in patients in order to provide rapid and appropriate care. A surface-enhanced Raman spectroscopy (SERS)-based method was successfully developed to rapidly measure cocaine in saliva at clinical concentrations, as low as 25 ng/mL. Pretreatment steps comprising chemical separation, physical separation, and solid-phase extraction were investigated to recover the analyte drug from the saliva matrix. Samples were analyzed using Fourier-transform (FT) and dispersive Raman systems, and statistical analysis of the results shows that the method is both reliable and accurate, and could be used to quantify unknown samples. The procedure requires minimal space and equipment and can be completed in less than 16 minutes. Finally, due to the inclusion of a buffer solution and the use of multiple robust pretreatment steps, with minimal further development this method could also be applied to other drugs of interest.

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.