Testing the cleaning effect of calcium salt deposition cleaning agent

Testing the effectiveness of calcium salt deposition cleaning agent for medical cleaning

Testing the cleaning effect of calcium salt deposition cleaning agent：

Calcium salt deposition in medical equipment has become an invisible killer that affects cleaning quality! According to data from the disinfection supply center of a tertiary hospital, the sterilization failure rate of bone surgery equipment due to calcium salt residue is as high as 3.2%, far exceeding the conventional cleaning failure rate (0.7%). These calcium magnesium complexes deposited in the joint gaps and inner walls of the instrument not only form biofilms to breed bacteria, but also accelerate the corrosion and aging of precision instruments. Medical YongTesting the cleaning effect of calcium salt deposition cleaning agentThe key technical means to solve this problem is to use scientific and quantitative detection methods to ensure that the cleaning agent can effectively dissolve stubborn calcium salts, ensuring the cleanliness and safety of medical equipment.

Testing standard system and method framework

The detection of calcium salt deposition cleaning effect requires the establishment of a dual technical system of 'basic standards+special verification'. The national standard GB/T 33422-2023 "Method for detecting biofilm contamination in medical equipment" provides a basic framework for determining pollutant removal rates, while in industry practice, simulated calcium salt contamination models are commonly used for targeted testing. This model refers to Appendix C of ISO 15883-5:2024. Calcium chloride and disodium phosphate are mixed in a 3:1 molar ratio and reacted at 37 ℃ and pH 7.2 to form hydroxyapatite crystals. A calcium salt layer with a thickness of 80 ± 5 μ m is formed on the surface of a 316L stainless steel carrier using a spin coating method, which is then sterilized under high pressure at 121 ℃ for 20 minutes to simulate the stubborn deposition formed after repeated disinfection of clinical instruments.

In terms of effectiveness evaluation, YY/T 0734.3-2025 "Medical cleaning agents Part 3: Determination of removal of special pollutants" specifies core parameters: calcium salt removal rate must reach 99.5% or more, residual amount ≤ 0.1mg/cm ²; The calcium salt penetration clearance rate of luminal instruments (inner diameter 1-3mm) should be ≥ 95% to ensure no residue in complex structural areas. At the same time, it is required that the dissolution rate of calcium salts by the cleaning agent be ≥ 0.5mg/min to meet the clinical demand for rapid cleaning.

Core testing items and technical methods

Quantitative determination of calcium salt removal efficiency

Adopting the combined technique of weight method and inductively coupled plasma mass spectrometry (ICP-MS). Soak the contaminated carrier in a cleaning solution at (50 ± 2) ℃ for 30 minutes (simulating ultrasonic cleaning process), remove it, rinse it three times with deionized water, and dry it at 105 ℃ to constant weight. The weight method uses an electronic balance (with an accuracy of 0.1mg) to measure the difference in carrier mass before and after cleaning, and calculate the calcium salt removal rate; The ICP-MS method is used for precise residual analysis. After microwave digestion of the carrier with nitric acid perchloric acid (3:1), the concentration of calcium element is determined under the instrument detection limit of 0.01 μ g/L, and converted into residual amount per unit area. A certain brand of specialized calcium salt cleaning agent achieved a weight based removal rate of 99.7% at a dilution ratio of 1:200. The residual amount measured by ICP-MS was only 0.032mg/cm ², which is better than the industry average level (0.078mg/cm ²).

Penetration and clearance test of luminal instruments

For complex structures such as endoscopic biopsy channels, segmented sampling method is adopted. Customized 316L stainless steel tube model (inner diameter 2mm, length 300mm, with 3 sampling sections: 0-100mm, 100-200mm, 200-300mm), with pre fabricated calcium salt coating on the inner wall. After circulating and rinsing with a cleaning agent (flow rate of 20mL/min, temperature of 45 ℃), samples were taken in sections using a specialized nylon brush. The eluent was filtered through a 0.45 μ m filter membrane and the calcium content was measured using an atomic absorption spectrometer (AAS). The qualified standard requires that the clearance rate of each section be ≥ 95%, and the difference in clearance rate between the last and first sections be ≤ 3%. A certain testing case shows that ordinary multi enzyme cleaning agents have a clearance rate of only 82% for the 200-300mm segment, while calcium salt specific cleaning agents can reach 96.3%, significantly reducing the risk of blind spots in the lumen.

Corrosion compatibility verification

Calcium salt cleaning agents usually contain acidic components, and their corrosive effects on medical equipment need to be evaluated simultaneously. Referring to GB/T 25102.1-2010 "Electroplated Galvanized Steel Sheet and Strip Part 1: Technical Conditions", 304 stainless steel, titanium alloy, and copper alloy test pieces (50mm × 25mm × 2mm) were soaked in a cleaning solution at (50 ± 2) ℃ for 168 hours, and the corrosion rate was analyzed by weight loss method and electrochemical impedance spectroscopy (EIS). The corrosion rate of high-quality products should be ≤ 0.002mm/a, and electrochemical testing shows a charge transfer resistance (Rct) change rate of ≤ 10%. In the testing of a certain product, the Rct value of the titanium alloy specimen decreased from 2560 Ω· cm ² to 2480 Ω· cm ² after immersion, with a change rate of only 3.1%, which meets the compatibility requirements.

Professional instrument configuration and operation specifications

The testing laboratory needs to be equipped with a three-level instrument system: basic analytical equipment includes Thermo Fisher iCAP RQ ICP-MS (resolution 0.01 amu), Shimadzu AA-7000 atomic absorption spectrometer (detection limit 0.001 μ g/mL), and Mettler XS205DU analytical balance (accuracy 0.1mg); Specialized equipment must meet the requirements of a lumen cleaning simulation system (adjustable flow rate of 0-50mL/min, temperature of 25-80 ℃) and an electrochemical workstation (frequency range of 10 ⁻²~10 ⁵ Hz); The sample pretreatment equipment includes CEM Mars 6 microwave digestion instrument (maximum temperature of 230 ℃) and Millipore ultrapure water system (resistivity of 18.2M Ω· cm).

The standardized operation process requires strict control of key links: the preparation of calcium salt contaminated carriers needs to be carried out in an ultra clean workbench, with 3 parallel samples taken from each batch; Dilute the cleaning agent using an automatic pipetting workstation (accuracy ± 0.5%); The eluent was filtered through a 0.45 μ m needle filter and immediately tested on the machine; Before ICP-MS detection, standard curves (R ² ≥ 0.999) need to be drawn using 10 μ g/L and 100 μ g/L calcium standard solutions. According to CNAS proficiency testing conducted by a certain laboratory, the relative standard deviation (RSD) of its calcium salt clearance determination results is only 2.3%, far below the industry allowed limit of 5%.

Clinical Application Value and Quality Control

The cleaning effect of calcium salt deposition is directly related to surgical safety and instrument lifespan. According to third-party testing data, the use of standardized calcium salt cleaning agents can increase the sterilization qualification rate of orthopedic instruments from 96.8% to 99.9%, and prolong the maintenance time of lens clarity by three times. After a certain teaching hospital introduced specialized testing, the average service life of stainless steel pliers was extended from 3 years to 5.2 years, and the annual equipment procurement cost was reduced by 38%.

Suggest that medical institutions establish a graded quality control system: conduct comprehensive testing on newly purchased calcium salt cleaning agents (removal rate, corrosion rate, toxicity, etc.); Perform rapid screening of calcium salt clearance rate for each batch of products (using X-ray fluorescence spectroscopy, with results obtained within 5 minutes); Monthly sampling verification of the actual cleaning effect of the disinfection supply center (with a focus on monitoring orthopedic and neurosurgical instruments). At the same time, pay attention to optimizing the use conditions of cleaning agents, such as controlling the water temperature at 45-55 ℃ to improve the efficiency of calcium salt dissolution. When formulating enzyme preparations, it is necessary to verify the effect of calcium ions on enzyme activity (requiring enzyme activity retention rate ≥ 85%).

With the popularization of micro chaung surgery and the continuous improvement of instrument refinement, the detection of calcium salt deposition cleaning effect will be upgraded from 'standard detection' to 'efficiency optimization'. In the future, biomimetic pollution models (such as composite calcium salt deposition containing blood proteins) can be developed, combined with ATP bioluminescence rapid detection technology, to construct an evaluation system that is more closely related to clinical practice, providing scientific basis for optimizing cleaning agent formulations and improving clinical cleaning processes.