Instrument for quantitative analysis

An instrument for detecting light produced in a reaction between first and second materials for performing quantitative analysis of said first material, which instrument comprises:

• housing means for defining an optically sealable hollow chamber having an opening;
• a cell holder, housed in said chamber, for supporting a cell therein, said cell holder being movable between a first position in which said cell is placed in and taken out of said cell holder through said opening of said housing means, and a second position in which said first material reacts with said second material;
• carrying means for carrying said cell holder between said first and second positions wherein said carrying means comprises a horizontally extending member between said first and second position, said cell holder being slidable on said horizontally extending member in a longitudinal direction;
• injection means for injecting said first and second materials into said cell when said cell holder is in said second position;
• measuring means for measuring the quantity of light produced by the reaction between said first and second materials, said measuring means having a light passage and a light detecting means for detecting light passing through said light passage and impinging on said light detecting means;
• first protective means, associated with said opening, for blocking light from being introduced into said housing means from the outside thereof, said first protective means being operable between an open position in which said first protective means fully opens said opening of the housing means in a first operation mode, and a closed position in which said first protective means fully closes said opening in a second operation mode;
• second protective means, associated with said light passage of the measuring means, for blocking light from impinging on said light detecting means of the measuring means, said second protective means being operable between an open position in which said second protective means fully opens said light passage in said second operation mode, and a closed position in which said second protective means fully closes said light passage in said first operation mode;
• cell holder detecting means for monitoring said cell holder for producing a first signal when said cell holder is disposed at said first position, and a second signal when said cell holder is disposed at said second position;
• wherein said cell holder detecting means includes first and second switches, said first switch being turned on when a communication between said cell holder and said first switch is established in said first position, and said second switch being turned on when a communication between said cell holder and said second switch is established in said second position, said cell holder detecting means producing said first signal in response to turning ON of said first switch, and said second signal in response to turning ON of said second switch, and wherein aid first and second switches respectively are provided at the ends of said horizontally extending member, and wherein said first and second switches respectively project vertically from the ends of said horizontally extending member, and said cell holder has first and second recesses on the bottom thereof, said first and second switches being respectively engageable with said first and second recesses;
• and
• control means for receiving said signals produced by said cell holder detecting means for adjusting said first and second protective means such that said first and second protective means operate in said first operation mode when said control means receives said first signal, and in said second operation mode when said control means receives said second signal.