Ionizer for vapor analysis decoupling the ionization region from the analyzer

A method to ionize vapors carried in a sample gas for analysis in an analytical instrument, the method comprising:

• providing an apparatus having an ionization chamber and an adjacent impaction chamber separated by an impaction plate having an impaction orifice defined therein;
• introducing said sample gas at a flow rate Qs into said ionization chamber including a source of charged particles, such that some among said vapors in said sample gas make contact with said charged particles to become ionized vapors;
• introducing clean gas into said impaction chamber;
• providing one or more electric fields such that some among said ionized vapors are guided through said impaction orifice, through said clean gas in said impaction chamber,
• mixing therein said ionized vapors with said clean gas, and
• wherein said analytical instrument samples the mixture of said ionized vapors and said clean gas produced in said impaction chamber though an inlet orifice ingesting an inlet flow rate QA, and
• wherein, said impaction orifice is configured such that said sample gas passes through said impaction orifice to define a jet therethrough extending into said impaction chamber, said jet minimizing said clean gas from passing through said impaction orifice from said impaction chamber and into said ionization chamber, and
• wherein, said jet of sample gas collides against said flow of clean gas introduced in said impaction chamber, both flows colliding in the impaction chamber such that penetration of said flow of clean gas into said ionization chamber is minimized,