Analysis by real-time PCR of five transport and conservation mediums of nasopharyngeal swab samples to COVID-19 diagnosis in Santiago of Chile.

Due to the COVID-19 pandemic, many transport kits have been manufactured to preserve and transport nasopharyngeal swab samples (NPSs) from patients. However, there is no information on the performance of the different virus transport media (VTM) used in COVID-19 diagnosis in the population of Santiago de Chile. We compared the RT-qPCR amplification profile of five different viral transport kit mediums, including DNA/RNA Shield™, NAT, VTM-N, Ezmedlab™, and phosphate-buffered saline (PBS), for NPSs from Central Metropolitan Health Service, Santiago, Chile. The DNA/RNA Shield™ medium showed a better performance in terms of Cq and RFU values for the internal reference RNase P and viral ORF1ab probes. By contrast, the PBS transport medium registered higher Cq values for the viral and reference gene, compared to the other VTM. DNA/RNA Shield™ shows higher relative fluorescence units (RFUs) and lower Cq values for the reference gene. Collectively, our results suggest that the PBS medium could compromise the sample diagnosis because of its lower RT-qPCR performance. The NAT, Ezmedlab and VTM-N, and DNA/RNA Shield™ media show acceptable RT-qPCR parameters and, consequently, seem suitable for use in COVID-19 diagnosis.

2-[2-(4-Nitro-phen-yl)hydrazinyl-idene]-1,3-diphenyl-propane-1,3-dione.

In the mol-ecular structure of the title compound, C(21)H(15)N(3)O(4), the inter-planar angle between the benzoyl units is 89.7 (1)°. The corresponding angles between the phenyl-hydrazono and the benzoyl groups are 31.4 (3) and 60.8 (2)°, respectively. In the crystal, a strong resonance-assisted intra-molecular hydrogen bond (N-H⋯O) and a weak intra-molecular hydrogen bond (C-H⋯N) strongly affect the observed conformation of the mol-ecule. The crystal packing is determined by a strong inter-molecular hydrogen bond (N-H⋯O), giving rise to a helical chain along the a axis. In addition, two weak inter-molecular contacts (C-H⋯O) are observed.

A second monoclinic polymorph of 2-[2-(4-meth-oxy-phen-yl)hydrazinyl-idene]-1,3-diphenyl-propane-1,3-dione.

The title compound, C(22)H(18)N(2)O(3) is the second monoclinic polymorph (P2(1)/c) of the compound, the first being reported in space group P2(1) [Bertolasi et al. (1993 ▶). J. Chem. Soc. Perkin Trans. 2, pp. 2223-2228]. In the mol-ecular structure of the title compound, the inter-planar angle between the benzoyl units is 80.04 (5)°, while the corresponding angles between the phenyl-hydrazinyl-idene and benzoyl groups are 36.11 (5) and 55.77 (2)°. A strong resonance-assisted intra-molecular N-H⋯O hydrogen bond is found. In the crystal, the entire supra-molecular structure is constructed by weak inter-molecular C-H⋯O inter-actions and an inter-ring π-π inter-action [centroid-centroid distance = 3.6088 (8) Å].

2-[2-(4-Acetyl-phen-yl)hydrazinyl-idene]-1,3-diphenyl-propane-1,3-dione.

In the title compound, C(23)H(18)N(2)O(3), the inter-planar angle between the benzoyl units is 80.51 (6)° while the dihedral angles between the hydrazinyl-idene and benzoyl groups are 43.43 (6) and 54.16 (6)°. In the crystal, a strong resonance-assisted intra-molecular N-H⋯O hydrogen bond is observed. The mol-ecules form an inversion dimer via a pair of weak C-H⋯O hydrogen bonds and a π-π inter-action [centroid-centroid distance of 3.5719 (10) Å]. These dimers are linked via weak C-H⋯O contacts, forming chains along the b axis.