Reagent 1 preparation for CO230 and NO230 instruments (Full model numbers PST-CO230 and PST-NO230)
When using analytical instruments, reagent quality and preparation matter just as much as the instrument itself. Customers using the PST-CO230 and PST-NO230 occasionally ask what “Reagent 1” is, how it is prepared, and why hydrochloric acid is used.
This article explains the purpose of Reagent 1 in clear, practical terms and provides guidance on safe, standard laboratory preparation practices.
What is Reagent 1?
Reagent 1 is an aqueous hydrochloric acid solution used to establish the correct chemical conditions for CO₂ and nitrite measurement. The acidification step ensures consistent sample behaviour and repeatable results across measurements.
Why hydrochloric acid?
Hydrochloric acid is widely used in analytical chemistry because it is:
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well characterised,
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stable when diluted,
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and does not introduce interfering ions into most analytical reactions.
For laboratory and educational use, hydrochloric acid is supplied as an Analytical Reagent (AR) grade chemical, meaning impurities are tightly controlled.
Why dilution is important in preparation of reagent 1 for NO230 and CO230.
Concentrated hydrochloric acid (37% w/w) is not used directly when preparing reagent 1 for the NO230 and CO230. Instead, it is diluted with water to produce a controlled, moderate-strength reagent that is:
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safer to handle,
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easier to reproduce,
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suitable for routine testing environments.
A standard 1:9 dilution produces a solution of approximately 1.2 mol/L, which is appropriate for PST-CO230 and PST-NO230 applications.
Download the Reagent 1 Preparation SOP (PDF)
A one-page, lab-ready procedure for PST-CO230 and PST-NO230 users.
[Download the SOP]
