How should proper blank correction be handled? What are the methods that should be used?

In my opinion, blank correction should not be made. Instead, information should be provided about the levels detected in blanks of varying kinds - with the range, average and standard deviation reported. This then allows readers to draw their own conclusions the extent to which reported levels in samples are influenced by sample contamination.

Multiple types of blanks should be included. Blank correction could be done subtractively or using thresholds (set a detection threshold based on the highest blank value or mean + 3×SD; only applicable in instances in which the blank value is significantly lower than those from samples). In FTIR and Raman analyses, particle type matching can be done (subtracting only the particles that match those on the blank in shape, size and color). 
Best practices should include reporting of blank values alongside sample results, including replicate blanks (to assess variability) and use statistical methods to determine if differences are significant.

The procedure of proper blank correction is an accurate adjustment of a measurement or analytical results that can account for background signals, contamination, or interference that does not come from the analyte of interest. This correction is crucial in analytical techniques like chemical analysis, spectrophotometry, chromatography, and similar procedures. The general process of blank correction starts with the preparation of a blank sample that contains all the reagents except the analyte. The blank needs to be measured under the same conditions as the test sample. The signal obtained for the blank sample is then subtracted from the sample signal in order to obtain a corrected value, and this correction should be applied consistently across all measurements. 
Usually, several blank correction methods are used depending on the application and study.
1. The reagent blank have the purpose of correcting for reagent reactivity in spectrophotometry and titration.
2.The method blank helps identify  the contamination during sample preparation in trace or environmental analyses.
3. The instrumental blanks are used to measure the baseline signal of the instruments in spectroscopy and mass spectrometry.
4. The calibration blanks, that contain no analyte, are usually used for creating calibration curves. 
 The methods that should be used for attaining best practices include matching the blank’s matrix to the sample (ensuring that the blank closely matches the matrix and conditions of the actual sample to provide accurate baseline comparisons), using multiple blanks to monitor contamination or drift. Also, a thorough documentation of when and how blank corrections were applied should be maintained in reports or lab notebooks for transparency and reproducibility documenting procedures. Additionally, validating that the blank is truly free of the analyte of interest is essential, as any contamination could distort the results and lead to inaccurate conclusions. 

The approach should be to correct at the lowest possible level. If this is not done, then there will always be the need to apply correction factors based upon extrapolation. Extrapolation implies multiplying uncertainties and this should be avoided as much as possible.

Appropriate handling of blank value is critical to avoid false positive or false negative results for MNPs. Because blanks play a critical role in establishing method detection limits of MNPs, when analyzed using microscopy or spectroscopy, blank correction has significant implications.  However, with a pyrolysis GC-MS method, detection limit is mainly influenced by instrumental sensitivity and mass of samples extracted for analysis.  Thus, this aspect of blank correction is different depending on the analytical technique used.

The best way to handle blank correction is use of  expert judgement and it may vary study to study or batch to batch.  Inclusion of several blanks in every batch of sample analysis is recommended and a mean value for that batch is subtracted from sample values.  However, uncertainty associated with blank value should be reported in methodology (mean, range and RSD of MNP levels found in blanks).  With a complete disclosure of blank results, readers should be able to understand the uncertainty associated with data.

Report results of blanks, whether they be field blanks for process blanks. If blank results are reported along with the other analytical results, the reader/user can then determine for themselves how they would like to process the information.

It depends on the nature of the blank signal. If it is consistent blank signal with known contribution source, the blank signal can be corrected by subtracting the blank from any sample signal to get a true sample signal. If the blank signal is random and unknown source of introduction, then the blank signal should be treated as a control signal and statistically compared to sample signal for significance. 

I approve of the method suggested in the paper.  Dont subtract (unless very specific particle matches between the blank and samples), just report the numbers and types.

There are different types of blanks, reagent blanks, method blanks, instrument blanks and field blanks. Each type of blanks should be studied separately and corrected if time and funding allow.  

The most common correction method is subtracting the blank response from the sample response. Another correction method is using calibration curves which include the blank response.