Enhanced Compound Analysis Using Reactive Paper Spray Mass Spectrometry: Leveraging Schiff Base Reaction for Amino Acid Detection.

Paper spray mass spectrometry (PS-MS) has evolved into a promising tool for monitoring reactions in thin films and microdroplets, known as reactive PS, alongside its established role in ambient and direct ionization. This study addresses the need for rapid, cost-effective methods to improve analyte identification in biofluids by leveraging reactive PS-MS in clinical chemistry environments. The technique has proven effective in derivatizing target analytes, altering hydrophobicity to enhance elution and ionization efficiency, and refining detection through thin-film reactions on paper, significantly expediting reaction rates by using amino acids (AAs) as model analytes. These molecules are prone to interacting with substrates like paper, impeding elution and detection. Additionally, highly abundant species in biofluids, such as lipids, often suppress AA ionization. This study employs the Schiff base (SB) reaction utilizing aromatic aldehydes for AA derivatization to optimize reaction conditions time, temperature, and catalyst presence and dramatically increasing the conversion ratio (CR) of formed SB. For instance, using leucine as a model AA, the CR surged from 57% at room temperature to 89% at 70 °C, with added pyridine during and after 7.5 min, displaying a 43% CR compared to the bulk reaction. Evaluation of various aromatic aldehydes as derivatization agents highlighted the importance of specific oxygen substituents for achieving higher conversion rates. Furthermore, diverse derivatization agents unveiled unique fragmentation pathways, aiding in-depth annotation of the target analyte. Successfully applied to quantify AAs in human and rat plasma, this reactive PS-MS approach showcases promising potential in efficiently detecting conventionally challenging compounds in PS-MS analysis.

Accuracy of non-invasive sensors measuring core body temperature in cardiac surgery ICU patients - results from a monocentric prospective observational study.

PURPOSE: Temperature monitoring in the perioperative setting often represents a compromise between accuracy, invasiveness of probe placement, and patient comfort. Transcutaneous sensors using the Zero-Heat-Flux (ZHF) and Double-Sensor (DS) technology have been developed and evaluated in a variety of clinical settings. The present study is the first to compare the performance of both sensors simultaneously with temperature measured by a Swan-Ganz catheter (PAC) in patients admitted to the intensive care unit (ICU) after cardiac surgery. METHODS: In this monocentric prospective observational study patients were postoperatively transferred to the ICU and both sensors were placed on the patients' foreheads. Core body temperature measured by intraoperatively placed PAC served as gold standard. Measurements were recorded at 5-minute intervals and up to 40 data sets per patient were recorded. Bland and Altman's method for repeated measurements was used to analyse agreement. Subgroup analyses for gender, body-mass-index, core temperature, airway status and different time intervals were performed. Lin's concordance correlation coefficient (LCCC) was calculated, as well as sensitivity and specificity for detecting hyperthermia (≥ 38 °C) and hypothermia (< 36 °C). RESULTS: Over a period of six month, we collected 1600 sets of DS, ZHF, and PAC measurements, from a total of 40 patients. Bland-Altman analysis revealed a mean bias of -0.82 ± 1.27 °C (average ± 95% Limits-of-Agreement (LoA)) and - 0.54 ± 1.14 °C for DS and ZHF, respectively. The LCCC was 0.5 (DS) and 0.63 (ZHF). Mean bias was significantly higher in hyperthermic and hypothermic patients. Sensitivity and specificity were 0.12 / 0.99 (DS) and 0.35 / 1.0 (ZHF) for hyperthermia and 0.95 / 0.72 (DS) and 1.0 / 0.85 (ZHF) for hypothermia. CONCLUSION: Core temperature was generally underestimated by the non-invasive approaches. In our study, ZHF outperformed DS. In terms of agreement, results for both sensors were outside the range that is considered clinically acceptable. Nevertheless, both sensors might be adequate to detect postoperative hypothermia reliably when more invasive methods are not available or appropriate. TRIAL REGISTRATION: German Register of Clinical Trials (DRKS-ID: DRKS00027003), retrospectively registered 10/28/2021.

Ion Heating in Advanced Dielectric Barrier Discharge Ion Sources for Ambient Mass Spectrometry.

Dielectric barrier discharges (DBD) are highly versatile plasma sources for forming ions at atmospheric pressure and near ambient temperatures for the rapid, direct, and sensitive analysis of molecules by mass spectrometry (MS). Ambient ion sources should ideally form intact ions, as in-source fragmentation can limit sensitivity, increase spectral complexity, and hinder interpretation. Here, we report the measurement of ion internal energy distributions for the four primary classes of DBD-based ion sources, specifically DBD ionization (DBDI), low-temperature plasma (LTP), flexible microtube plasma (FµTP), and active capillary plasma ionization (ACaPI), in addition to atmospheric pressure chemical ionization (APCI) using para-substituted benzylammonium thermometer ions. Surprisingly, the average extent of energy deposited by the use of ACaPI (90.6 kJ mol-1) was ∼40 kJ mol-1 lower than the other ion sources (DBDI, LTP, FµTP, and APCI; 130.2 to 134.1 kJ mol-1) in their conventional configurations, and slightly higher than electrospray ionization (80.8 kJ mol-1). The internal energy distributions did not depend strongly on the sample introduction conditions (i.e., the use of different solvents and sample vaporization temperatures) or the DBD plasma conditions (i.e., maximum applied voltage). By positioning the DBDI, LTP, and FµTP plasma jets on axis with the capillary entrance to the mass spectrometer, the extent of internal energy deposition could be reduced by up to 20 kJ mol-1, although at the expense of sensitivity. Overall, the use of an active capillary-based DBD can result in substantially less fragmentation of ions with labile bonds than alternate DBD sources and APCI with comparably high sensitivity.

Flexible Microtube Plasma for the Consecutive-Ionization of Cholesterol in Nano-Electrospray Mass Spectrometry.

Electrospray ionization mass spectrometry (ESI-MS) is an established method for the identification of biomarkers. By nano-ESI (nESI), the polar molecular fraction of complex biological samples can be successfully ionized. In contrast, the less-polar free cholesterol, which serves as an important biomarker for several human diseases, is barely accessible by nESI. Although, complex scan functions of modern high-resolution MS devices are able to increase the signal-to-noise ratio, they are limited by the ionization efficiency of the nESI. One possible method to increase the ionization efficiency is the derivatization with acetyl chloride, however interferences with cholesteryl esters must be considered, so chromatographic separation or complex scan functions may be required. A novel approach to increase the yield of cholesterol ions of the nESI could be the application of a second consecutive-ionization process. This publication presents the flexible microtube plasma (FµTP) as a consecutive-ionization source, which allows the determination of cholesterol in nESI-MS analysis. Focusing on the analytical performance, the nESI-FµTP approach increases the cholesterol signal yield in a complex liver extract by a factor of 49. The repeatability and long-term stability could be successfully evaluated. A linear dynamic range of 1.7 orders of magnitude, a minimum detectability of 5.46 mg/L, and a high accuracy (deviation, -8.1%) demonstrates the nESI-FµTP-MS as an excellent approach for a derivatization-free determination of cholesterol.

Dielectric Barrier Discharge Ionization Mechanisms: Polycyclic Aromatic Hydrocarbons as a Case of Study.

Dielectric barrier discharge ionization (DBDI) is a versatile tool for small-molecule mass spectrometry applications, helping cover from polar to low polar molecules. However, the plasma gas-phase interactions are highly complex and have been scarcely investigated. The ionization mechanisms of plasmas have long been assumed to be somewhat similar to atmospheric pressure chemical ionization (APCI). Here, we evaluated the ionization mechanisms of a two-ring DBDI ion source, using different discharge gases to analyze vaporized liquid samples. Polycyclic aromatic hydrocarbons (PAHs) were used as model analytes to assess the mechanisms' dominance: protonation, [M + H]+, or radical ion species formation, [M]·+. In the present work, two different ionization trends were observed for APCI and DBDI during the PAH analysis; the compounds with proton affinities (PA) over 856 kJ/mol were detected as [M + H]+ when APCI was used as ionization source. Meanwhile, independently of the PA, DBDI showed the prevalence of charge exchange reactions. The addition of dopants in the gas-phase region shifted the ionization mechanisms toward charge exchange reactions, facilitating the formation of [M]·+ ion species, showing anisole a significant boost of the PAH radical ion species signals, over nine times for Ar-Prop-DBDI analysis. The presence of high-energy metastable atoms (e.g., HeM) with high ionization potentials (IE = 19.80 eV) did not show boosted PAH abundances or extensive molecule fragmentation. Moreover, other species in the plasma jet region with closer and more appropriate IE, such as N2 B3Πg excited molecules, are likely responsible for PAH Penning ionization.

Liquid chromatography-dielectric barrier discharge ionization mass spectrometry for the analysis of neutral lipids of archaeological interest.

Dielectric barrier discharge ionization has gained attention in the last few years due to its versatility and the vast array of molecules that can be ionized. In this study, we report on the assessment of liquid chromatography coupled to dielectric barrier discharge ionization with mass spectrometry for neutral lipid analysis. A set of different neutral lipid subclasses (triacylglycerides, diacylglycerides, and sterols) were selected for the study. The main species detected from our ionization source were [M-H2 O+H]+ , [M+H]+ or [M-R-H2 O+H]+ , attributed to sterol dehydration, protonation or the fragmentation of an acyl chain accompanied by a water loss of the glycerolipids, respectively. In terms of sensitivity, the dielectric barrier discharge displayed overall improved abundances and comparable or better limits of quantitation than atmospheric pressure chemical ionization for both acylglycerols and sterols. As a case study, different archaeological samples with variable content in neutral lipids, particularly triacylglycerides, were studied. The identification was carried out by combining accurate mass and the tentative formula associated with the exact mass, retention time matching with standards, and additional structural information from in-source fragmentation. The high degree of unsaturation and the presence of sterols revealed the potential vegetal origin of the material stored in the analyzed samples.

Ionization of semi-fluorinated n-alkanes in controlled atmosphere using flexible micro-tube plasma (FµTP) ionization source with square- and sine-wave voltage.

Non-thermal plasma-based ionization sources have been widely used and shown excellent soft ionization performance in mass spectrometry. Despite their extensive application, the ionization mechanisms of these sources are of great interest for further exploring their full potential. A controlled atmosphere can provide a clean and controllable ionization environment and is beneficial for studying the ionization mechanism. The plasma source itself also has a significant impact on the ionization mechanism of the analyte, and the voltage waveform is one of the key parameters for controlling the plasma source. In this paper, a miniature flexible micro-tube plasma (FµTP) ionization source was sustained using both square and sine-wave voltage. The ionization processes of typical semi-fluorinated n-alkanes (SFAs) were investigated in the controlled atmosphere filled with 80% N2 and 20% O2. The main mass peaks using both square and sine-wave voltages are found to be [M-mH]+ and [M-mH+nO]+ (m = 1, 3; n = 0, 1, 2). However, for the square-wave voltage, the [M-H+O]+ species are the most abundant while [M-H]+ species are dominant for the sine-wave voltage, showing that the plasma generated with sine-wave voltage is somewhat "softer" than the one with square-wave voltage for SFAs. With the assistance of optical spectroscopy, the plasma developments in one discharge cycle for both voltage waveforms were obtained. Only one discharge can be found in each half cycle for square-wave voltage while several for the sine-wave voltage. These would be responsible for the different ionization behaviors in these two cases. This work provides more insight into the ionization mechanism of SFAs and more understanding of plasma-based soft ionization. In addition, the analytical performance was evaluated to be comparable when using these two voltage generators with a big difference in cost, which will benefit the instrumental development.

Methaemoglobinemia after Liposuction under Tumescent Local Anaesthesia - Diagnostic Value of Pulse Oximetry.

Background: Tumescent local anaesthesia with prilocain can lead to clinically significant methemoglobin levels. New generation multiple wavelength pulse oximeters (e. g. Masimo Radical 7®) can measure methemoglobin levels. Methods: In this prospective observational study we compared the venous methemoglobin levels and the corresponding pulse oximetric values of the Radical 7® in patients undergoing tumescent local anaesthesia for liposuction procedures. The measurements were performed in Hanseklinik, Luebeck, Germany between 2008 and 2011. Results: In 133 patients, we measured a maximum methemoglobin level of 18 per cent. In a Bland-Altman analysis we found a mean bias of +2.2 % (-4.1 to 8.4 limits of agreement) for pulse oximetric values compared to hemoximetry. Conclusion: Pulse oximetric measurement of methemoglobin is an early-warning tool for the detection of clinically significant methaemoglobinemia in patients with tumescent local anaesthesia.

Coupling paper spray ionization with the flexible microtube plasma for the determination of low polar biomarkers in mass spectrometry.

A fast and precise analysis of complex biological samples is one of the most important challenges in clinical- and life-sciences. In this field, the paper spray ionization (PSI) becomes a more and more successful ambient ionization technique for mass spectrometry. The PSI is based on the electrospray mechanism and is limited to polar target analytes. In this work, a transition from the paper spray ionization to a corona discharge under standard PSI conditions is observed and evaluated by using a complex liver sample. This evaluation leads to an advancement of the PSI by adding a flexible microtube plasma (FµTP) that is more efficient in respect to non- and low polar molecules. The combination of the PSI and the FµTP in a sequential way allows the determination of polar lipids as well as non-polar compounds like cholesterol and possible lung cancer biomarkers. As add-on for PSI, this approach enhances the number of detectable species in one single measurement and seems to be a powerful tool for the rapid analysis of complex biological samples in clinical- and life-sciences.

Pulsed Blue Laser Diode Thermal Desorption Microplasma Imaging Mass Spectrometry.

An ambient air laser desorption, plasma ionization imaging method is developed and presented using a microsecond pulsed laser diode for desorption and a flexible microtube plasma for ionization of the neutral desorbate. Inherent parameters such as the laser repetition rate and pulse width are optimized to the imaging application. For the desorption substrate, copper spots on a copper-glass sandwich structure are used. This novel design enables imaging without ablating the metal into the mass spectrometer. On this substrate, fixed calibration markers are used to decrease the positioning error in the imaging process, featuring a 3D offset correction within the experiment. The image is both screened spot-by-spot and per line scanning at a constant speed, which allows direct comparison. In spot-by-spot scanning, a novel algorithm is presented to unfold and to reconstruct the imaging data. This approach significantly decreases the time required for the imaging process, which allows imaging even at decreased sampling rates and thus higher mass resolution. After the experiment, the raw data is automatically converted and interpreted by a second algorithm, which allows direct visualization of the image from the data, even on low-intensity signals. Mouse liver microtome cuts have been screened for dehydrated cholesterol, proving good agreement of the unfolded data with the morphology of the tissue. The method optically resolves 30 µm, with 30 µm diameter copper spots and a 10 µm gap. No conventional chemical matrices or vacuum conditions are required.

Technology-Assisted Collaborative Care Program for People with Diabetes and/or High Blood Pressure Attending Primary Health Care: A Feasibility Study.

The comorbidity of depression with physical chronic diseases is usually not considered in clinical guidelines. This study evaluated the feasibility of a technology-assisted collaborative care (TCC) program for depression in people with diabetes and/or high blood pressure (DM/HBP) attending a primary health care (PHC) facility in Santiago, Chile. Twenty people diagnosed with DM/HBP having a Patient Health Questionnaire-9 score ≥ 15 points were recruited. The TCC program consisted of a face-to-face, computer-assisted psychosocial intervention (CPI, five biweekly sessions), telephone monitoring (TM), and a mobile phone application for behavioral activation (CONEMO). Assessments of depressive symptoms and other health-related outcomes were made. Thirteen patients completed the CAPI, 12 received TM, and none tried CONEMO. The TCC program was potentially efficacious in treating depression, with two-thirds of participants achieving response to depression treatment 12 weeks after baseline. Decreases were observed in depressive symptoms and healthcare visits and increases in mental health-related quality of life and adherence to treatment. Patients perceived the CPI as acceptable. The TCC program was partially feasible and potentially efficacious for managing depression in people with DM/HBP. These data are valuable inputs for a future randomized clinical trial.

Evaluation of a novel controlled-atmosphere flexible microtube plasma soft ionization source for the determination of BTEX in olive oil by headspace-gas chromatography/mass spectrometry.

Although electron impact ionization (EI) remains the standard ionization source for GC-MS, it presents extensive fragmentation as its main limitation. The potential of a novel plasma-based soft ionization source named controlled-atmosphere flexible microtube plasma (CA-FµTP) has been evaluated in this work for the determination of monoaromatic volatile BTEX group (namely benzene, toluene, ethylbenzene, and o-, m- and p-xylenes) in olive oil, based on headspace technique. The obtained results show an attractive advantage over EI due to no fragmentation was observed. A nitrosated ion [M + NO]+ is obtained as the most abundant species. Thus, the BTEX mass spectrum identification can be carried out without major effort. In general, the sensitivity for CA-FµTP was comparable to those obtained by EI, achieving LODs ranged from 0.6 to 1.0 µg kg-1. The potential usefulness of GC-CA-FµTP-MS for the detection of BTEX was demonstrated by analyzing olive oil samples and identifying traces of these compounds in one sample. Therefore, the proposed plasma-based soft ionization is suitable for BTEX analysis in fatty complex matrixes as olive oil.

Review: Miniature dielectric barrier discharge (DBD) in analytical atomic spectrometry.

The development of miniature, sensitive, high throughput, and in-situ analytical instruments has been becoming developing field of modern analytical chemistry. Due to its unique advantages such as easy operation, simple configuration, ambient working temperature and pressure, low power consumption, and miniature dimension, dielectric barrier discharge (DBD) has always been a hot topic in analytical chemistry. This review gives an overview of miniature DBD application in analytical atomic spectrometry, starting with an introduction to its geometrical configuration and ionization mechanisms. Then, its applications such as excitation or atomization sources in atomic emission spectrometry (AES), atomic absorption spectrometry (AAS) and atomic fluorescence spectrometry (AFS) are reviewed. Also, its application as vapor generation system in atomic spectrometry is discussed.

Detection and Evaluation of Lipid Classes and Other Hydrophobic Compounds Using a Laser Desorption/Plasma Ionization Interface.

Ionization mechanisms of different lipid classes and other hydrophobic compounds have been evaluated in an ambient air laser-desorption flexible microtube plasma ionization (LD-FµTPi) setup, without sample manipulation. Lipids require a minimum laser fluency of 27 W/mm2 for efficient desorption and detection, providing the possibility for temperature-programmed laser desorption of different lipid classes. The flexible microtube plasma (FµTP) produces oxygen addition to double bonds, even to polyunsaturated molecules. The characteristic fragmentation pattern of phospholipids consisting of the neutral loss of the phosphocholine head group was verified. The formation of dimers due to hydrogen bonding and dispersion forces was observed as well. In this sense, soft ionization capabilities of the FµTP were proven in both ion modes. Ambient air mass spectrometry methods often suffer from decreased reproducibility, for instance, due to changing atmospheric conditions or sensitive positioning of the ion source. It was shown that neutrals become increasingly unstable above a distance of 7 ± 1 mm to the spectrometer's inlet, providing estimates for the free volume in LD-FµTPi MS. In this sense, no guided transport is required. The ion plume ejected from the plasma can be altered by applying a bias voltage to the copper substrate. Ions can be detected at -950 V, 300 V (negative ion mode) and -400 V, 900 V (positive ion mode), respectively. The ions are guided through an internal electric field gradient of the FµTP that arises from charged capillary walls, ideal for ion detection. In conclusion, this makes the method fast, robust, and flexible.

Validación inicial de Patient Health Questionnaire 2-Item para detectar síntomas depresivos en diabéticos y/o hipertensos en la atención primaria de salud

Background: Patient Health Questionnaire (PHQ-9) has nine questions and is used in diabetic or hypertensive patients to detect depressive symptoms. The PHQ-2 uses the first two questions of the PHQ-9 to rapidly detect those patients that should answer the whole questionnaire. Aim: To validate the PHQ-2 to detect depressive symptoms in diabetic or hypertensive patients consulting at Primary Health Care (PHC). Material and Methods: Secondary analysis of data obtained during the baseline assessment of a clinical trial. Diabetic and hypertensive patients aged 18 years or more, attending a public health care clinic of Metropolitan Santiago, were invited to participate. Those accepting, answered the Patient Health Questionnaire (PHQ-9), consisting in nine questions about depressive symptoms. Demographics and health data were also collected. The PHQ-2 capacity to discriminate PHQ-9 scores equal or higher than 10 and 15 and the correlation between both versions, were assessed. Results: Ninety-four participants aged 64 ± years (73% women) answered the questionnaire. A cut-off score of 3 or more points in the PHQ-2 achieved the best tradeoff between sensitivity and specificity for discriminating PHQ-9 scores equal or higher than 10 (area under the receiver operating characteristic curve (ROC) = 0.92, 95% confidence interval [95% CI] = 0.87 to 0.97) and 15 points (area under the ROC curve = 0.95, 95% CI = 0.92 to 0.99). Both versions had a high positive correlation (r = 0.87). Conclusions: The PHQ-2 allows a stepped, simple and accurate screening for depressive symptoms. Diabetic or hypertensive patients with 3 or more points should be immediately assessed with the remaining questions of the PHQ-9.

Stepwise optimization of a Flexible Microtube Plasma (FµTP) as an ionization source for Ion Mobility Spectrometry.

The ionization source is the central system of analytical devices such as mass spectrometers or ion mobility spectrometers. In this study, a recently developed flexible microtube plasma (FµTP) is applied as an ionization source for a custom-made drift tube ion mobility spectrometer (IMS) for the first time. The FµTP is based on a highly miniaturized, robust and a small-footprint dielectric barrier discharge design with an outstanding ionization efficiency. In this study, the experimental setup of the FµTP was further improved upon to achieve optimal coupling conditions in terms of the ion mobility spectrometry sensitivity and the plasma gas consumption. One major focus of this study was the adjustment of the electrical operation parameters, in particular, the high voltage amplitude, frequency and duty cycle, in order to minimize the electric field disturbances and yield higher signals. Additionally, the consumption of helium plasma gas was reduced by refining the FµTP. It was found that the ionization efficiency could be significantly enhanced by increasing the plasma high voltage and through application of a duty cycle up to 90:10. Plasma gas flows could be reduced down to 3 mL min-1 by increasing the plasma high voltage amplitude. Furthermore, a smaller wire electrode design enables the operation of the FµTP with nitrogen and clean air. Moreover, detection limits of a homologous series of ketones in the range of 330 pptv (N2-FµTP, 2-decanone) down to 20 pptv (He-FµTP, 2-octanone) could be reached in the optimized setup. To sum up, this feasibility study demonstrates the potential of the optimized FµTP as a powerful ionization source for ion mobility spectrometry especially with regard to ionization efficiency.

Study of Controlled Atmosphere Flexible Microtube Plasma Soft Ionization Mass Spectrometry for Detection of Volatile Organic Compounds as Potential Biomarkers in Saliva for Cancer.

A new soft ionization device for mass spectrometry is presented using the flexible microtube plasma under controlled atmospheric conditions. The controlled atmosphere flexible microtube plasma consists of the plasma source itself connected to a gas chromatograph and a mass spectrometer using a borosilicate glass cross piece. Controlled atmosphere, for example, nitrogen and/or an oxygen mixture, is introduced to the system to create a clean ionization environment. Reproducibility issues are discussed, and solutions are presented manipulating the gas flow in the cross piece. A proof of concept is shown using a ketone mixture introduced to the mass spectrometer to optimize atmospheric conditions. Furthermore, application of the presented device for the sensitive and nonfragmenting ionization of volatile organic biomarkers relevant for cancer is carried out. Sample treatment for human saliva is described, and relevant candidate biomarkers are measured in the saliva matrix, showing a very good ionization efficiency and neglectable matrix effects with limits of detection below 80 ppt.

Standardization of Sandwich-Structured Cu-Glass Substrates Embedded in a Flexible Diode Laser-Plasma Interface for the Detection of Cholesterol.

This study introduced sandwich-structured copper-glass substrates for standardization of laser desorption and plasma ionization. For standardized quantitative analysis, cavities were constructed which allow better reproducibility in droplet deposition and for laser application. Applying the diode laser, molten substrate material is incorporated into the glass, being trapped inside. Therefore, this method can be separated from laser ablation, achieving high ion signals without ablating material from the surface. Flexible microtube plasma (FµTP) was selected as the ionization source, this being the first time that laser desorption and FµTP ionization are coupled. This laser-plasma interface was applied to the detection of cholesterol, which showed a significantly improved limit of detection of 0.46 ng and linear dynamic range of 3 orders of magnitude in positive ion mode compared to other (ambient air mass spectrometry) methods. The main reason was the change of phase on the copper surface. The dehydrated molecule [M-H2O+H]+ was the base peak of the spectrum and no further dissociation or fragmentation was observed. Blood plasma was spiked with cholesterol. In a 1:100 chloroform dilution, the presence of the plasma was neglectable and led to the same detection limits and linear dynamic range as in the cholesterol standard. No sample preparation or internal standards were needed for calibration. The physical effects of the surface modification were investigated, including the calculation of the laser beam waist to simplify the comparison and reproducibility of results.

[Validation of patient health Questionnaire-2 to detect depressive symptoms in diabetic or hypertensive patients]. / Validación inicial de Patient Health Questionnaire 2-Item para detectar síntomas depresivos en diabéticos y/o hipertensos en la atención primaria de salud.

BACKGROUND: Patient Health Questionnaire (PHQ-9) has nine questions and is used in diabetic or hypertensive patients to detect depressive symptoms. The PHQ-2 uses the first two questions of the PHQ-9 to rapidly detect those patients that should answer the whole questionnaire. AIM: To validate the PHQ-2 to detect depressive symptoms in diabetic or hypertensive patients consulting at Primary Health Care (PHC). MATERIAL AND METHODS: Secondary analysis of data obtained during the baseline assessment of a clinical trial. Diabetic and hypertensive patients aged 18 years or more, attending a public health care clinic of Metropolitan Santiago, were invited to participate. Those accepting, answered the Patient Health Questionnaire (PHQ-9), consisting in nine questions about depressive symptoms. Demographics and health data were also collected. The PHQ-2 capacity to discriminate PHQ-9 scores equal or higher than 10 and 15 and the correlation between both versions, were assessed. RESULTS: Ninety-four participants aged 64 ± years (73% women) answered the questionnaire. A cut-off score of 3 or more points in the PHQ-2 achieved the best tradeoff between sensitivity and specificity for discriminating PHQ-9 scores equal or higher than 10 (area under the receiver operating characteristic curve (ROC) = 0.92, 95% confidence interval [95% CI] = 0.87 to 0.97) and 15 points (area under the ROC curve = 0.95, 95% CI = 0.92 to 0.99). Both versions had a high positive correlation (r = 0.87). CONCLUSIONS: The PHQ-2 allows a stepped, simple and accurate screening for depressive symptoms. Diabetic or hypertensive patients with 3 or more points should be immediately assessed with the remaining questions of the PHQ-9.

Detection of multiclass explosives and related compounds in soil and water by liquid chromatography-dielectric barrier discharge ionization-mass spectrometry.

In this work, the multiclass detection of explosives and related compounds has been studied by liquid chromatography-high-resolution mass spectrometry by means of a time-of-flight mass spectrometer (TOFMS) operated in the negative ion mode, using dielectric barrier discharge ionization (DBDI). Reversed-phase high-performance liquid chromatography (HPLC) separation was performed using water-methanol mobile phase without any modifier, although the effect of ammonium acetate was studied. DBD plasma was generated by applying a square wave voltage of 2.5 kV to a 100-mL min-1 He flow. The DBDI probe was adjusted to fit the commercial API source housing so that the HPLC eluent was nebulized and vaporized in the same manner as for atmospheric-pressure chemical ionization (APCI). The ionization process was affected by the temperature of the two nitrogen streams used to vaporize the solvent and the analytes, particularly for RDX and HMX, which are thermolabile compounds. The best approach in terms of sensitivity for all the studied compounds was the use of a gradient of temperatures in the ionization source, starting at 225/200 °C (vaporizer/drying gas temp) for nitramines and ending at 350/325 °C for nitroaromatic compounds. High-resolution full-scan spectra of individual selected compounds were recorded by LC-DBDI-TOFMS, and the results were compared to LC-APCI-TOFMS. A better sensitivity (slope of calibration curve) was obtained by DBDI for more than 70% of the studied compounds in both wastewater and soil extracts. Graphical abstract ᅟ.