Please see attached Report.

This manuscript presents the use of ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) as a tool to quantify sugars in atmospheric PM at very low concentrations. The authors provide a description of the preparation and measurement procedures and give an in-depth validation of the method’s standard analytical criteria. This technique was then applied to ambient samples from the high altitude station “Jungfraujoch”, providing a time series of five years. The authors demonstrate that sample preparation and analysis can be obtained in relatively short lab time. They show the observation of a seasonal cycle for three of the measured sugars and discuss their trends qualitatively.  

Many different sugars have been measured in particulate matter but analysis is so far quite demanding due to the low concentrations and low selectivity of available analytical techniques. As sugars may comprise a large fraction of PM, more and better measurements are needed for quantification and tracking their origin. The authors show that UHPLC-MS/MS can be used to quantify a large range of sugars at very low concentrations. They tested 28 different sugars and show, that 21 of them can be used for quantitative analysis. The validation of the method is sound and the description of procedures and calculations sufficiently complete and precise to allow their reproduction by fellow scientists.

They apply the method to filter samples taken at “Jungfraujoch”, a relatively unpolluted environment, demonstrating that it also performs well at fairly low concentrations. The discussion of the results of this time series is reasonable, albeit only qualitative. It is mentioned that a more comprehensive analysis including other measured species will follow. The paper is clearly written and I recommend the manuscript to be published. I have only a few minor comments that should be considered.

Add the mass resolution of the mass spectrometer. In Table 1 m/z is reported in 3 digits. However, isomers show different m/z, although they should be the same (e.g. fructose, glucose). Probably mass resolution is not that high.

Equation 1and Table 2: Why do you use an absolute value for bias? Thus, the direction of the bias cannot be seen.

Table S2: You do not report the molecular mass but Q1. Clarify this.

Line 66; Sentence not clear (However…)

Line 80: replace tgenerally by generally

Line 120: replace “et” by and

Line 128: not correct units of MQ-water

Line 130: MIX-SI stands for mixture of internal standards. I recommend using MIX-IS. I assume you used the French abbreviation.

Line 305: others, replace by other