I work in a factory, which produces analytic instruments. I work in a factory which produces analytic instruments.

With a comma, it looks like you’re defining any and all factories as places that make analytics instruments. This isn’t true as factories can make different things

I work in a factory, which that produces analytic instruments. I work in a factory that produces analytic instruments.

"which produces" is correct for grammar, but is a bit awkward for native speakers. It is a better phrase to use if you are writing a formal paper.

The most popular producing devices are gas chromatography(GC) and mass spectrometry detectors (MSD). The most popular producing devices are gas chromatography(GC) and mass spectrometry detectors (MSD).

The most popularfrequently producinged devices are gas chromatography(GC) and mass spectrometry detector(MSD). The most frequently produced devices are gas chromatography(GC) and mass spectrometry detector(MSD).

I think it says nothing for you.Sorry, I don’t understand what you were trying to say! Sorry, I don’t understand what you were trying to say!

I think it saythis means nothing forto you. I think this means nothing to you.

I will try to explain what is thatthese are. I will try to explain what these are.

(Similarly, if in another example you were talking about one object, you would say “what this is.”

I will try to explain what is thatthese are. I will try to explain what these are.

GS is a complicated instrument which separates compounds of a sample on a special capillary column. GS is a complicated instrument which separates compounds of a sample on a special capillary column.

GS is a complicated instrument which separates compounds of a sample on a special capillary column. GS is a complicated instrument which separates compounds of a sample on a special capillary column.

After separation, compounds are goingo one by one into MSD. After separation, compounds go one by one into MSD.

After separation compounds are goingo one by one into the MSD. After separation compounds go one by one into the MSD.

In the MSD system, the compound is bombarded by electrons. In the MSD system, the compound is bombarded by electrons.

MSD is gettings a special spectrum, which produces individuals [elements] for each compound. MSD is gets a special spectrum, which produces individual [elements] for each compound.

I was not entirely sure what you wanted to say here. "Individuals" usually only means "individual people."

AfterThen, the software compares a library spectra andto the obtained spectra by the MSD system. Then, the software compares a library spectra to the obtained spectra by the MSD system.