temperature measurement in the clinical laboratory ... good enough isn\'t good enough.

by:Sinowon     2020-01-03
Temperature is used in the clinical laboratory environment to maintain the stability of the test samples.
Standard operating procedures for GLP and individual laboratories require monitoring of environmental parameters for specialized testing facilities.
Therefore, the laboratory environment, analytical reactions, instruments and materials must be monitored to the required temperature.
This includes instruments, incubators, refrigerators-
Freezer and specimen room.
Monitoring these temperatures is not 9-to-5job . . .
24/7, including weekends and holidays
This article provides a quick overview of the importance of temperature measurement in clinical laboratories, as well as some common misconceptions about the instruments used, and what can be done to help maintain temperature control.
Temperature: a series of physical parameters, including humidity, pressure and airflow, need to be measured in the first parameter clinical laboratory.
But the temperature is too high.
This is a basic component of most analytical measurements.
You\'re not making estimates.
Even if there is no one in the lab, you need to know exactly what the temperature is.
The CDC sub-department is K Sec 493. 1252, 1253 and.
5126 this is covered for laboratories, instruments and materials.
Most test systems used for in vitro testing are biologically sourced.
They are usually highly sensitive, so their control conditions (
Temperature, etc)
Very important.
As the temperature changes, the physical performance changes as well.
If the temperature is over 35 [or so], the stability of the reagent that remains at \"room temperature\" is reduceddegrees]C.
Under atmospheric pressure, the viscosity of aqueous solution decreases with the increase of temperature, generally about 2% per [degrees]C.
You can see this in the patient samples taken out of the refrigerator, and the viscosity of these samples is different from the equilibrium viscosity at room temperature.
Since water is usually used as a reference, it also has different viscosity at different temperatures.
Common analytical methods, such as fluorescence analysis, can also be sensitive to changes in temperature (and pH)of the sample.
Common analysis of ALT and AST is performed at different temperatures, usually 30 [degrees]C for 37[degrees]C.
All of this highlights the need for measurements at constant temperature and why many clinical laboratories operate at room temperature.
But what is \"room temperature? Macro vs.
Generally speaking, the \"macro\" environment deals with the laboratory work area itself.
The term \"room temperature\" is commonly used here \".
\"For most laboratories, the room temperature is usually 20 [degrees]or 25[degrees]C (293[degrees]or 298[degrees]K,68[degrees]or 779[degrees]F).
However, unlike standard temperatures and pressures, room temperature is not a uniformly defined scientific term (STP)
There are also several definitions.
Room temperature usually refers to the temperature in the temperature-
Control the building.
The term \"ambient temperature\" associated with it simply represents the local temperature and can be the same as the indoor room temperature.
All of this depends on the design and performance of the HVAC system that serves the chemical laboratory.
According to the air supply, typical laboratories can have \"hot spots\" and \"cold spots\"
Returns the position and air flow mode.
This in turn affects the room temperature assumed and measured.
This is particularly important in controlled areas such as Operation Room, isolation room and pharmacy storage area.
Since HVAC systems rely on pressure to move the air, even minor variations in the differential pressure can have an impact on the air being delivered and on the local temperature.
The temperature mapping of the laboratory work area can determine the area where the temperature is unstable.
The \"mini\" environment deals with smaller control areas such as incubators, refrigerators/freezers, coolers for O blood storage and transportation. R.
Biological safety cover, pharmacy preparation sterile isolator, etc.
Here, different methods of temperature mapping, sensor selection and placement are required compared to the macro environment.
While it is hoped that the \"Penny in acup\" temperature monitoring method will no longer be used, the limitation of the scope of establishing reagents, samples and other materials in a mini-environment presents its own challenge.
Some common misconceptions about temperature measurement-
Inaccurate temperature measurement is always difficult.
It is not always difficult.
This is sometimes challenging.
It depends on the measured material and your expectations for accuracy.
For example, at low temperatures (-200[degrees]C)
[Accuracy]+ or -]5[degrees]
C can be careful, [+ or -]0. 1[degrees]
C may be difficult. From0[degrees]C to 50[degrees]C, [+ or -]5[degrees]C is easy, [+ or-]0. 1[degrees]
C is sometimes a challenge.
Some measurement difficulties are related to the thermal gradient in the material being measured, especially for materials with poor thermal conductivity, such as plastic.
There is no thermal gradient in the laboratory. Yes, they do.
In fact, they are often a common cause of measurement errors.
Especially when measuring materials with poor thermal conductivity, such as air, most liquids and materials with poor non-thermal conductivity, you can see thisSolid metal.
Just measure the temperature of a high ice bath beaker and you can see the vertical temperature gradient of several degrees (
Do not use a metal thermometer).
If I use a calibrated sensor, my reading is accurate. Not necessarily.
Even the calibrated thermometer will end up with errors due to offset, scale, and linear errors.
In addition, any temperature sensor may drift over time due to the temperature cycle. Hysteresis (
When the measured value depends on the leader\'s contact from whichit)
Can be in simple bimetallic (dial)thermometers.
Make sure all temperature measuring instruments are already using NIST-
Certified references or have Current NIST (
Or other requirements)
Certification from an external metrology laboratory. For in-
House certification, CLSI File 12-
A2 describes the program to be used. (1)
When I measure, I am measuring the temperature of the sample.
What you actually measure is the temperature of the sensor.
Except for non-
Contact temperature measuring device (e. g.
, No thermometer)
Heat conduction is the cause of temperature.
All temperature sensors respond quickly to temperature changes.
In fact, there is a big change in response time.
Some sensors respond in less than a second, while others take a few minutes.
The time when the sensor reaches the measured value of 99% is called \"[t. sub. 99]\" time.
Use this feature to compare various temperature sensors and match them with the analysis process.
Thermometer with digital reading
Out is the most accurate.
Unfortunately, the measuring device attached to the sensor is perfect.
Calibration, linear, and temperature-related errors may exist in digital meters, chart recorders, or data recorders.
Ensure that your NIST calibration of the device includes calibration of the total sensor-read-
Since the effect of temperature on the read-out device may also be a subtle source of error, the output system is therefore.
I have a temperature sensor in my fridge so it is good enough. Maybe not.
Most refrigerators use a simple thermocouple that usually drifts over time.
Compare the temperature reading of this thermocouple using a separate NIST
With certified digital thermometers, you may find differences even in different areas of the refrigerator.
Not all temperature sensors are common temperature sensors in clinical laboratories, such as thermocouple, thermometer and RTDs.
Quick comparisons help to understand why the two are different.
The thermocouple is based on the effect that the junction between two different metals produces a voltage that rises with temperature.
Compared with resistance
The type thermometer and thermocouple have the advantage of a maximum temperature cap of up to several thousand degrees Celsius.
Their reaction time is very fast, but their reaction time is very long.
Poor stability and poor measurement accuracy.
They are often used in ovens and other instruments where the temperature is higher than 250 [degrees]C.
The thermocouple is an acceptable lower part-
Cost solutions for industrial temperature measurement can be found in many laboratory instruments.
The Athermister is made of certain metal oxides whose resistance decreases as the temperature rises.
Because of this, they are called negative temperature coefficients (NTC)sensors.
They are usually used for instruments and measurements of about 200 or less [degrees]
Because they are smaller in size, have a smaller thermal mass, and have a reasonable response time.
Resistance Temperature Detector (RTDs)
The characteristic of metal resistance changing with temperature is used.
They are positive temperature coefficients (PTC)
A sensor whose resistance increases with temperature.
The main metals used are platinum and nickel, while the most widely used sensors are platinum resistance thermometers of 100 ohms or 1000 ohms.
RTDs is the most accurate sensor for temperature measurement with very good long timeterm stability.
The typical accuracy of platinum resistance thermometer is [+ or -]0. 5[degrees]
Some designs are more [+ or -]0. 07[degrees]C.
The clinical laboratory has different design and performance features, usually relying on the instrument manufacturer to design the appropriate sensor for the task, and in most cases the selected sensor is sufficient.
However, the instrument should be selected and certified considering the specific application.
Ensuring that the temperature sensors used meet the application, accuracy, and accuracy requirements means paying attention to the instrument\'s features and then testing according to your requirements.
In high-precision applications, you may not want to use a thermocouple.
In addition, it is not recommended to use an athermeter with a penetration probe for liquid measurement of ambient air temperature. Calibrated vs.
The two terms commonly used in measurement after adjustment are often misunderstood.
The first term is \"calibration\" and the second term is \"adjustment \".
\"We generally interpret\" calibration \"as laboratory instruments have been tested in the metro lab and a certificate has been returned to demonstrate the accuracy of the test parameters.
This means that the metrology laboratory has tested the laboratory instruments according to the manufacturer\'s specifications and has certified their performance.
This does not actually mean that laboratory instruments are \"adjusted\" to meet the design specifications.
Laboratory instruments may have been received in the thermal engineering laboratory and found to be operating within the manufacturer\'s specifications, so no adjustment is required.
However, if it is found that the laboratory instrument does not meet the manufacturer\'s specifications, then it needs to be \"adjusted\" to make its performance meet the requirements.
You can see this on the calibration certificate in Find (incoming)and \"as left\" (outgoing)
Performance documentation.
The aging of the instrument sensor can be judged by the actual amount of adjustment required for a period of time.
Certification bodies such as JCAHO (
Joint Committee)
Laboratory instruments that require NIST certification.
In general, however, NIST does not require or recommend any set recalibrating intervals for measuring standards or instruments.
The specific calibration interval depends on many factors.
These may include the following: * precision requirements set by the laboratory * requirements set by regulations * environmental factors that may affect the stable operation of the instrument * inherent stability of a particular device or instrument.
Accuracy is not an automatic temperature measurement accuracy established by calibration.
The whole measurement system \"(sensor andread-out device)
It should be traceable to known standards.
This standard should be more accurate than the equipment you are calibrating.
It makes no sense to calibrate [the data logger]+ or-]0. 5[degrees]
C. The accuracy of the simple double metal dial thermometer is [+ or -]2[degrees]C.
By doing so, there is no point in calibration.
If you don\'t know anything about the accuracy of the reference standard, then \"NIST traceable\" means very little.
NISTtraceability does not necessarily mean \"accurate\", so make sure \"NIST-
Certified equipment. Automated vs.
Manual temperature monitoring let us not forget that it is these people who record laboratory temperature data and are responsible for this data.
Work load and time pressure make this a challenge.
While the manual system works well if managed properly, there are more reliable and reliable automation systems available today.
The \"reliable\" function in the automatic temperature monitoring system comes from its alarm and recording function.
The temperature out of control generates an instant alarm of 24/7, so corrective action can be taken quickly.
Some systems even notify you by email or text message.
The second equally important design feature is automated documentation.
Each part of the automatic temperature measurement system is recorded and regular reports are generated for monitoring and trend analysis.
The same automated documentation helps
Changeable data files and electronic signatures.
These same automatic temperature monitoring systems can be used for drug formulation (
For example, in a hospital pharmacy)
21CFR Part 11 requirements are met.
We take temperature measurements for granted because they are an integral part of the day --to-
The daily operation of the laboratory.
Therefore, the laboratory environment (Macro and Micro)
, Plus personal instruments, storage areas, etc.
, Must be continuously monitored.
The challenge we face is not just to do this, but to do it right: Choose the right components, understand their strengths and limitations, ensure their accuracy to meet regulatory requirements, and remain necessary
Record \"room temperature\" as20 next time 【degrees]
C, check if you actually read out the measurement results from a verified accurate, reliable thermometer. Reference (1. )
Institute of Clinical and Laboratory standards.
The temperature of the bathtub, instrument and temperature sensor is recalibrated. SecondEdition.
CLSI Document 12-approved standard 1990A2.
Robert Bove is marketing manager for industrial products range in New Jersey
Headquartered in detu
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