There are many noise signals in original laser induced breakdown spectroscopy (LIBS) spectra.To explore the effect of spectral pretreatment on LIBS information by different filter methods, the LIBS spectra of Pb-polluted cabbage in wavelength range of 400.45-410.98 nm was investigated and preprocessed by adjacent averaging, Savitzky-Golay (S-G) and fast Fourier transformation (FFT).Then partial least square (PLS) model was established for evaluating the spectral treatment effect.The result showed that the root mean square error of prediction (RMSEP) and average relative error of S-G method were 0.26 and 3.7%, suggesting a superior smoothing effect than other methods.Experimental results indicated that an appropriate filtering method could help to improve the spectral quality and raise the precision of model checkout.

Objective:This study aims to evaluate the performance of digital PCR (dPCR) detecting multiple and single copies genes of the Epstein-Barr virus (EBV) for nucleic acid quantification and explore their applicability in clinical settings.Methods:Compared the sensitivity, specificity, precision, lower limit of detection (LoD), and linearity for multicopy BamHI-W dPCR and single-copy EBNA1 dPCR systems. Linear regression analysis using the least squares method was employed to evaluate the linearity. Additionally, we analyzed plasma samples from 182 patients with suspected EBV-related diseases between January and July 2022 at the Southern Medical University Southern Hospital, using both dPCR and quantitative PCR (qPCR) for EBV DNA quantification. Linear regression analysis using the least squares method was conducted to assess their quantitative correlation.Results:The dPCR systems for both multicopy and single-copy genes showed excellent linearity ( R 2 values of 0.992 and 0.997, respectively, both P<0.001). The LoD were 188 IU/ml for BamHI-W gene and 358 IU/ml for EBNA1 gene dPCR systems. The logarithmic coefficient of variation ( CV) values for high-concentration samples (1 000 000 IU/ml) were 0.34% and 0.21% for the BamHI-W gene and EBNA1 gene dPCR assays, respectively, while for low-concentration samples (5 000 IU/ml) were 0.98% and 0.64%, respectively. In the detection of seven common clinical infectious pathogens and EBV positive samples, only EBV-positive samples yielded positive signals in the dPCR detection system, with no cross-reaction with other pathogens. In 182 samples, the positive detection rates were 47.80% (87/182) for BamHI-W gene and 35.16% (64/182) for EBNA1 gene dPCR, compared to 43.41% (79/182) for qPCR. Linear correlation analysis with qPCR showed R2 values of 0.837 for BamHI-W gene and 0.763 for EBNA1 gene dPCR (both P<0.001). The BamHI-W gene copy number ranged from 3 to 18 copies per clinical sample, with patient-specific variations. There was a high consistency in viral load trends between the multicopy BamHI-W gene and single-copy EBNA1 gene dPCR systems within individual patients. Conclusions:The dPCR methods detecting EBV multiple and single copies genes showed high sensitivity, specificity, precision, and quantitative accuracy, suitable for clinical sample analysis. The multicopy BamHI-W gene dPCR method notably enhances detection sensitivity and can be used as a supplement to current EBV DNA load detection methods, especially in low-concentration samples. For within-patient EBV DNA monitoring, the multicopy gene method proves more effective, while inter-patient comparisons might necessitate single-copy gene methods or normalize them using the same standard.