Sorptive tape-spray tandem mass spectrometry using aluminum foil coated with mixed-mode microparticles

Direct mass spectrometry (MS) is an exciting strategy in bioanalysis, enabling rapid decision-making in different scenarios. Its application is usually hindered by matrix effects and the typically low concentration of the target compounds in the biofluids. In this sense, combining a previous sample preparation step minimizes or removes these shortcomings. This article describes sorptive tape-spray tandem mass spectrometry (STS-MS/MS) based on mixed-mode particles as a strategy to combine sample preparation and MS analysis in a single device. The technique uses a sorptive tape (ST) consisting of mixed-mode polymeric microparticles (combining ionic exchange and hydrophobic interactions) coated over aluminum foil in a spatial controlled way. The tapes act as the sorptive phases to isolate the analytes from the sample matrix and substrates for STS-MS/MS. The performance of the technique has been evaluated by developing a method to determine codeine in saliva as proof of concept. The affordability of the STs elements allows the preparation of many individual phases at low cost so that several samples can be extracted simultaneously, thus increasing the sample throughput. The extraction variables were optimized following a multivariate approach. Working under the optimum conditions, the limit of detection was 0.3 μg L-1, while the intraday precision, calculated as relative standard deviation (RSD) at three concentration levels, was better than 9.4 %. The accuracy, expressed as relative recovery, was in the range of 78-98 %. The method was also applied to the analysis of real samples. Despite being a powerful strategy, the direct combination of microextraction to MS is not always affordable in all laboratories. For this reason, the STs were also combined with commercial liquid chromatography-MS working under the direct infusion mode to demonstrate the usefulness of the ST in classical extraction workflows.

Sensitive, reliable and simultaneous determination of Fingolimod and Citalopram drug molecules used in multiple sclerosis treatment based on magnetic solid phase extraction and HPLC-PDA

An analytical methodology has been developed for trace amounts of Fingolimod (FIN) and Citalopram (CIT) drug molecules based on magnetic solid phase extraction (MSPE) and high performance liquid chromatographic determination with photodiode array detector (HPLC-DAD). Fingolimod is used in treatment of Multiple sclerosis (MS) disease and sometimes antidepressant drugs such as citalopram accompany to treatment. Both simultaneous analysis of these molecules and application of MSPE with a new adsorbent has been performed for first times. Fe3O4@L-Tyrosine magnetic particles has been synthetized and characterized as a new magnetic adsorbent. Experimental variables of MPSE were examined and optimized step by step such as pH, adsorption and desorption conditions, time effect, etc. Analytical parameters of the proposed method were studied and determined under optimized conditions according to international guidelines. HPLC analysis of FIN and CIT molecules was performed by isocratic elution of a mixture of 50 % Acetonitrile, 40 % pH:3 phosphate buffer and 10 % methanol with flow rate 1.0 mL min-1. The chosen wavelengths in PDA was determined as 238 nm for FIN and 213 nm for CIT. The limits of detection (LOD) for proposed method were 6.32 ng mL-1 for FIN and 6.85 ng mL-1 for CIT molecules. RSD % values were lower than 5.5 % in analysis of model solutions including 250 and 500 ng mL-1 of target molecules. Recovery values by means of synthetic urine and saliva samples were in the range of 95.7-105.4 % for both molecules.

Accuracy of a raw saliva-based COVID-19 RT-LAMP diagnostic assay

The Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) pandemic demanded rapid diagnosis to isolate new COVID-19 cases and prevent disease transmission. Quantitative Real-Time Polymerase Chain Reaction (qRT-PCR) rapidly became the gold standard for diagnosis. However, due to the high cost and delay of the results, other types of diagnosis were implemented, such as COVID-19 Ag Rapid Tests and Reverse Transcription Technique followed by Loop-Mediated isothermal Amplification (RT-LAMP). In this work, we validated the use of RT-LAMP in saliva samples rather than nasopharyngeal swabs, as the collection is more comfortable. First, we selected 5 primer sets based on the limit of detection for SARS-CoV-2 RNA, then validated their sensitivity and specificity in patient samples. A total of 117 samples were analyzed by fluorometric RT-LAMP and compared with qRT-PCR results. Our results show that the use of a high-sensitive primer ORF1-a, together with a low-sensitive primer set Gene E (time to threshold of 22.9 and 36.4 minutes, respectively, using 200 copies of viral RNA), achieved sensitivity in purified RNA from saliva samples of 95.2% (95% CI 76.1‒99.8) with 90.5% specificity (95% CI 69.6‒98.8) (n = 42).As RNA purification increases the turnaround time, we tested the outcome of RT-LAMP utilizing raw saliva samples without purification. The test achieved a sensitivity of 81.8% (95% CI 59.7‒94.8) and a specificity of 90.9% (95% CI 70.8‒98.8). As a result, the accuracy of 92.9% (95% CI 80.5‒98.5) in purified RNA-saliva samples was lowered to an acceptable level of 86.4% (95% CI 72.6‒94.8) in raw saliva. Although mass vaccination has been implemented, new strains and low vaccination progress helped to spread COVID-19. This study shows that it is feasible to track new COVID-19 cases in a large population with the use of raw saliva as sample in RT-LAMP assay which yields accurate results and offers a less invasive test.

Monitoring of SARS-CoV-2 circulation using saliva testing in school children in Rome, Italy

Objectives

To describe the trend of SARS-CoV-2 RNA in saliva samples from children attending nine schools in Rome in the local surveillance unit RM3 during the period of September 2021-March 2022, in parallel with the trend of SARS-CoV-2 RNA observed in nasopharyngeal swabs (NPSs) from the population in the same catchment area that was routinely tested at our laboratory in the same period.

Methods

Saliva samples were collected using the Copan LolliSponge^TM device and analyzed by Aptima® SARS-CoV-2 Assay on the Panther® System. NPSs were tested using either Aptima® SARS-CoV-2 Assay or Alinity m SARS-CoV-2 Assay.

Results

The percentage of positivity in the two populations was different; of the 2222 saliva samples from students, 0.99% had positive results, whereas the percentage was higher (33.43%) in the 8994 NPSs representing the population from local surveillance unit RM3. Interestingly, the trend of SARS-CoV-2 RNA in saliva samples from students was consistent with that observed in NPSs from the population in same catchment area, although with peaks slightly anticipated.

Conclusion

Overall, screening of saliva in the schools represents a good system to monitor SARS-CoV-2 circulation in the population, allowing early detection and quick isolation of students who are asymptomatic with positive test results and thus prevention of virus transmission.

Modified magnetic-based solvent-assisted dispersive solid-phase extraction: application to the determination of cortisol and cortisone in human saliva

A modification of magnetic-based solvent-assisted dispersive solid-phase extraction (M-SA-DSPE) has been employed for the determination of the biomarkers cortisol and cortisone in saliva samples. M-SA-DSPE is based on the dispersion of the sorbent material by using a disperser solvent like in dispersive solid phase extraction (SA-DSPE) but a magnetic sorbent is used like in magnetic dispersive solid-phase extraction (M-DSPE). Thus, the magnetic sorbent containing the target analytes is retrieved using an external magnet like in M-DSPE. Finally, the analytes are desorbed into a small volume of organic solvent for the subsequent chromatographic analysis. To this regard, a M-SA-DSPE-based method was developed using a magnetic composite as sorbent, made of CoFe₂O₄ magnetic nanoparticles embedded into a reversed phase polymer (Strata-X^TM-RP), which exhibits affinity to the target analytes. Then, liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) was used to measure both analytes in the M-SA-DSPE extract. Under the optimized conditions, good analytical features were obtained: limits of detection of 0.029 ng mL^-1 for cortisol and 0.018 ng mL^-1 for cortisone, repeatability (as RSD) ≤ 10 %, and relative recoveries between 86 and 111 %, showing no significant matrix effects. Finally, the proposed method was applied to the analysis of saliva from different volunteers. This new methodology allows a fast and non-invasive determination of cortisol and cortisone, and it employs small amounts of sample, organic solvent and sorbent. Likewise, the sample treatment is minimum, since any supporting equipment (vortex, centrifuge, ultrasounds, etc.) is required.

Development of a method for the determination of polyamines including N-acetylated forms in human saliva via benzoylation and gas chromatography-mass spectrometry

A simple method for the determination of polyamines and their N-acetylated forms was developed using benzoyl chloride as derivatization reagent, and 1,6-diaminohexane as internal standard, followed by liquid-liquid extraction with ethyl acetate. The organic extract was injected in a gas chromatograph using a programmed temperature vaporizer and the determination and quantification was performed with a quadrupole mass spectrometer. There was no matrix effect with the proposed method, so internal calibration was used to quantify the corresponding derivatives. Good linear responses were obtained in the range from the limits of detection to 500 µg L^-1 (50 µg L^-1 for spermidine), with correlation coefficients varying from 0.9591 to 0.9968. The limits of quantification (S/N = 10) ranged 1.0 - 8.3 µg L^-1. Recoveries were found between 82 - 117%, showing the good accuracy of the proposed method. Intra- and inter-day precision assays, expressed as relative standard deviation (RSD) were evaluated at two different concentration levels (low and high), showing values in the range of 2.4 - 6.1% and 5.2 - 9.0% for repeatability and reproducibility, respectively (6.9 - 9.7% and 14.1 - 14.6% for spermidine). Successful determination of the studied polyamines and their N-acetylated forms was performed on the saliva of 17 volunteers.

Amine/phenyl gradient derived base layer as a comprehensive extractive phase for headspace cooled in-tube microextraction of volatile organic compounds in saliva

A gradient derived base layer extractive phase was synthesized and applied for the determination of volatile organic compounds (VOCs) in saliva samples using the headspace cooled in-tube microextraction (HS-CITME) method. The base layers from three different sols of phenyltriethoxysilane (PTES), octyltrimethoxysilane (OTMS) and methyltrimethoxysilane (MTMS) as nonpolar precursors were individually dip coated on the stainless steel wires (SSW). Then, the hydrolyzed polar precursor aminopropyltriethoxysilane (APTES) reacted with the silanol groups already formed on the surface of SSWs via controlled rate infusion (CRI) method. The presence of polar and non-polar functional groups on the surface of substrate was evaluated by Fourier-transform infrared spectroscopy (FTIR) while the morphology and thickness of the most suitable gradient coating (amine/phenyl) were also investigated by scanning electron microscopy (SEM). Assessment of the gradient extractive phase efficiency was carried out determining a group of VOCs with different polarities coupled with gas chromatography-mass spectrometry (GCMS) and the improved performance of the synthesized base layer coatings was observed. Furthermore, a cooling device was designed and implemented to the extracting system to improve the efficiency by influencing the exothermic nature of process. The data were analyzed by principal component analysis (PCA), and hierarchical cluster analysis (HCA) and the results were interpreted by polarities of analytes. Finally, under the optimized conditions, the limits of detection (LOD) and limits of quantification (LOQ) were 0.15 and 0.50 ng L^-1, respectively. The intra-day and inter-day relative standard deviations (RSDs) at 5 and 50 ng L^-1 (n = 3) using a single extractive phase were 2-6 and 10-17, respectively. The data associated with RSDs% for three extractive phases were between 16 and 19 %. Eventually, the method was conveniently applied to the extraction of VOCs from saliva samples of smokers and satisfactory relative recoveries (RR%) (95-108 %) were achieved and low quantities of VOCs were detected.

A preliminary study

Amino acids have been of great interest in clinical studies since variation in their concentration may provide information about different disorders. For the first time, a non-separative method based on single quadrupole mass spectrometry (qMS) for the simultaneous semiquantitative determination of sixteen amino acids in saliva samples has been developed. The method includes derivatisation of amino acids with ethyl chloroformate-pyridine-ethanol to obtain volatile products, liquid-liquid extraction (LLE) and further analysis using a programmed temperature vaporizer (PTV) coupled to qMS. This method could be applied to the analysis of a great number of saliva samples, limiting the use of separative methods only when abnormal concentrations of amino acids were found, reducing analysis time and cost. The results obtained in the determination of amino acids using the non-separative method were compared to those obtained when a separative method based on gas chromatography (GC) was used, providing values of average relative predictive error (E %) ranging between 2 and 48%. Repeatability and reproducibility were tested, obtaining relative standard deviation (RSD) values equal to or lower than 11% and 16%, respectively. Detection limits were in the range of 0.076-8.747 mg L^-1 for the non-separative method.

Prevalence of oral HPV infection among healthy individuals and head and neck cancer cases in the French West Indies

PURPOSE

Human papillomavirus (HPV) is known to play a role in the development of head and neck squamous cell carcinomas (HNSCC) and to date, no study has reported on the association between oral HPV infection and HNSCC in the Caribbean. The objective was to determine the prevalence of oral HPV infection in the French West Indies (FWI), overall and by HPV genotype, among HNSCC cases and healthy population controls.

METHOD

We used data from a population-based case-control study conducted in the FWI. The prevalence of oral HPV was estimated separately among 100 HNSCC cases (mean age 59 years) and 308 population controls (mean age 57 years). Odds ratios (OR) and 95% confidence intervals (CI) were estimated using a logistic regression adjusting for age, sex, tobacco, and alcohol consumption, to assess the association between oral HPV infection and HNSCC.

RESULTS

Prevalence of oral HPV infections was 26% in controls (30% in men and 14% in women) and 36% in HNSCC cases (36% in men, 33% in women). HPV52 was the most commonly detected genotype, in cases and in controls. The prevalence of HPV16, HPV33, and HPV51 was significantly higher in cases than in controls (p = 0.0340, p = 0.0472, and 0.0144, respectively). Oral infection with high-risk HPV was associated with an increase in risk of HNSCC (OR 1.99, 95% CI 0.95-4.15). HPV16 was only associated with oropharyngeal cancer (OR 16.01, 95% CI 1.67-153.64).

CONCLUSION

This study revealed a high prevalence of oral HPV infection in this middle-aged Afro-Caribbean population, and a specific distribution of HPV genotypes. These findings may provide insight into HNSCC etiology specific to the FWI.