Apparatus and method to measure concentration of disinfectant in medical device reprocessing system
A medical instrument processor includes an enclosure, a liquid distribution system, and a disinfectant concentration measuring subsystem. The enclosure is configured to hold a medical instrument. The liquid distribution system is configured to deliver a disinfection solution to a medical instrument within the enclosure. The liquid distribution system has a liquid outlet. The disinfectant concentration measuring subsystem includes a first mixing chamber in fluid communication with the liquid outlet, a pump that is configured to simultaneously pump the disinfection solution and the reagent solution into the first mixing chamber, and a concentration analysis assembly that is operable to determine a concentration of disinfectant in a sample solution that is output from the first mixing chamber. The reservoir is in fluid communication with the first mixing chamber.
1. A method for measuring a concentration of a disinfectant in a disinfection solution of a medical instrument processor, the method comprising:
(a) directing a flow of the disinfection solution into a first mixing chamber;
(b) directing a flow of a reagent solution into the first mixing chamber;
(c) mixing the disinfection solution and the reagent solution in the first mixing chamber to create a sample solution;
(d) directing the sample solution into a sample chamber comprising clear sides;
(e) passing light having a known first intensity and wavelength through the clear sides of the sample chamber and the sample solution in the sample chamber;
(f) measuring a second intensity of the light transmitted through the sample chamber and the sample solution in the sample chamber;
(g) determining a reaction product concentration in the sample solution based upon a difference between the known first intensity and the second intensity of the light; and
(h) determining the disinfectant concentration in the disinfection solution based upon the reaction product concentration;
wherein the reaction product is sodium hydroxide.
2. The method of claim 1 , wherein the disinfectant comprises ortho-phthalaldehyde.
3. The method of claim 1 , wherein the disinfection solution and the reagent solution are mixed in a volume to volume ratio of about 1:1 to create the sample solution.
4. The method of claim 1 , further comprising issuing an alert signal when the disinfectant concentration in the disinfection solution is below a predetermined value.
5. The method of claim 1 , further comprising:
(a) determining that the disinfectant concentration in the disinfection solution is below a predetermined value; and
(b) outputting the disinfectant solution from the medical instrument processor.
6. The method of claim 1 , further comprising:
(a) determining that the disinfectant concentration in the disinfection solution is not below a predetermined value; and
(b) recirculating the disinfectant solution in the medical instrument processor.
7. The method of claim 1 , comprising simultaneously directing the flow of the disinfection solution and the reagent solution into the first mixing chamber.
8. The method of claim 1 , further comprising:
(a) directing the disinfection solution and the reagent solution into a second mixing chamber; and
(b) mixing the disinfection solution and the reagent solution in the second mixing chamber to generate the sample solution.
9. The method of claim 8 , comprising:
(a) mixing the disinfection solution and the reagent solution in the first mixing chamber using a static mixer; and
(b) mixing the disinfection solution and the reagent solution in the second mixing chamber using a static mixer to generate the sample solution.
10. The method of claim 1 , further comprising directing the sample solution into a de-gassing module, prior to directing the sample solution into the sample chamber.
11. The method of claim 1 , further comprising measuring the temperature of the sample solution as it passes from the first mixing chamber into the sample chamber.
12. The method of claim 11 , further comprising making temperature corrections when determining the disinfectant concentration in the disinfection solution based upon the reaction product concentration.
13. The method of claim 8 , further comprising directing the sample solution into a de-gassing module prior to directing the sample solution into the sample chamber.
14. The method of claim 8 , further comprising measuring the temperature of the sample solution as it passes from the second mixing chamber into the sample chamber.
15. The method of claim 14 , further comprising making temperature corrections when determining the disinfectant concentration in the disinfection solution based upon the reaction product concentration.
16. A method for measuring a concentration of a disinfectant in a disinfection solution of a medical instrument processor, the method comprising:
(a) mixing the disinfection solution and a reagent solution in one or more mixing chambers to generate a sample solution;
(b) directing the sample solution into a sample chamber;
(c) passing light having a first intensity and wavelength through the sample chamber and the sample solution in the sample chamber;
(d) measuring a second intensity of the light transmitted through the sample chamber and the sample solution in the sample chamber;
(e) calculating a concentration of sodium hydroxide in the sample solution based upon a difference between the first intensity of the light and the second intensity of the light; and
(f) determining the disinfectant concentration in the disinfection solution based upon the concentration of sodium hydroxide in the sample solution.
17. The method of claim 16 , further comprising:
(a) determining that the disinfectant concentration in the disinfection solution is below a predetermined value; and
(b) outputting the disinfectant solution from the medical instrument processor.
18. The method of claim 16 , further comprising:
(a) determining that the disinfectant concentration in the disinfection solution is not below a predetermined value; and
(b) recirculating the disinfectant solution in the medical instrument processor.
19. A method for determining a concentration of ortho-phthalaldehyde in a disinfection solution of a medical instrument processor, the method comprising:
(a) mixing the disinfection solution and a reagent solution in one or more mixing chambers to generate a sample solution;
(b) directing the sample solution into a sample chamber;
(c) passing light having a first intensity of from about 70 millicandela to about 120 millicandela and a wavelength of from about 500 nanometers to about 600 nanometers through the sample chamber and the sample solution in the sample chamber;
(d) measuring a second intensity of the light transmitted through the sample chamber and the sample solution in the sample chamber;
(e) calculating a concentration of sodium hydroxide in the sample solution based upon a difference between the first intensity of the light and the second intensity of the light; and
(f) determining the concentration of ortho-phthalaldehyde in the disinfection solution based upon the calculated concentration of sodium hydroxide.
20. The method of claim 19 , further comprising either:
(a) determining that the disinfectant concentration in the disinfection solution is below a predetermined value and outputting the disinfectant solution from the medical instrument processor; or
(b) determining that the disinfectant concentration in the disinfection solution is not below a predetermined value and recirculating the disinfectant solution in the medical instrument processor.