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Combined Interpretations of the 2003, 2009, and 2016 Standards that apply to Volume 1 of the 2016 TNI Standard


Question:  How encompassing is the universe of “volumetric measuring devices” needing quarterly checks for accuracy?  Specifically, do graduated cylinders, glass to-deliver pipets, and other garden-variety glassware, which are not Class A, need to be checked quarterly?

TNI Response:  Yes. Graduated cylinders, glass to-deliver pipets, and other garden-variety glassware, which are not Class A, must be checked quarterly.


Question:  As written section appears to contradict itself in that section e reads: "glass microliter syringes and Class A glassware are exempt from any verification requirements beyond what is stated in Section 4.6.2." Then, upon reading section 4.6.2 states: "The laboratory shall ensure that purchased supplies and reagents and consumable materials that affect the quality of tests and/or calibrations are not used until they have been inspected or otherwise verified as complying with standard specifications or requirements defined in the methods for the tests and/or calibrations concerned. These services and supplies used shall comply with specified requirements. Records of actions taken to check compliance shall be maintained."

Can you clarify, per the Standard, if Class A glassware and glass microliter syringes have to be verified for accuracy upon receipt? Section e seems to indicate that these are accepted for accuracy; until you refer to section 4.6.2 which requires verification to specifications upon receipt.

TNI Response:  Volumetric verification is not required for glass microliter syringes or Class A glassware. Glass microliter syringes and Class A glassware are required to be inspected as complying with any specifications or requirements prior to first use. The laboratory decides how to perform the inspection or verification mentioned in 4.6.2 and must retain records of actions to check compliance.


Question:  The standard states "Volumetric dispensing devices (except Class A glassware and Glass microliter syringes) shall be checked for accuracy on a quarterly basis." Would class A plasticware be considered the same as Class A glassware ie - you do not need to check it on a quarterly basis?  Or would Class A plastic ware be considered the same as non-class A labware? The same question for V1M5 section iii.2.  "equipment such as filter funnels, bottles, non-Class A glassware, and other containers with volumetric markings (including sample analysis vessels) shall be verified once per lot prior to first use. This verification may be volumetric or gravimetric."  Would you need to check Class A plasticware once per lot?

TNI Response:  Plasticware is not glassware. Any volumetric dispensing devices that are not Class A glassware or glass microliter syringes must be checked for accuracy on a quarterly basis.


Question:  Does the NIST traceable reference, in this case a thermometer that is sent out annually to an accredited company for verification, as well as the laboratory support equipment which is verified against this thermometer, also need to be calibrated by that company over the range of use?

TNI Response:  A NIST-traceable reference sent out annually to an accredited company for verification or calibration is to be verified or calibrated over its entire range of use. Laboratory support equipment verified or calibrated in the laboratory against the NIST-traceable reference is to be verified or calibrated over its entire range of use. This section was revised in the 2016 standard to allow a single point verification "if the temperature measuring device is used over a range of 10°C or less."  This is obsolete and can be removed from web when 2009 Standard is no longer in use.


Question:  This section requires support equipment to be calibrated or verified annually with references "bracketing the range of use". The 2003 NELAC standard had comparable language requiring calibration or verification "over the entire range of use". Under the 2003 standard, an exception was permitted allowing the use of a single point calibration for narrow range use thermometers, such as those used for sample storage (>0-6C), BOD (20+/-1C) and micro incubators (35+/-0.5C and 44.5+/-0.2C), drying ovens (103C-105C), etc. However, the same exception has not been extrended to the 2009 TNI standard requirement. As a result, labs are being cited for not performing bracketing checks for these thermometers. Although the AB for the state where this issue developed allows the use of a temperature at or below and at or above the boundary of the range of use, the requirement still requires the lab to take the equipment out of normal use and re-adjust the settings multiple times. The process provides data that is probably less reliable than a single point check and requires significantly more time to perform. For example, a single point check in the range of 44.3-44.5 C for a fecal incubator would seem to be better data than a check around 40C and a second around 50C.

TNI Response:  An exemption for narrow range use thermometers is not described in the 2003 NELAC Standard and historical data does not provide that an exemption was made on an organizational level. The use of a single point calibration/verification check for the narrow use range thermometers exemption is not described in the 2009 TNI Standard.  This section was revised in the 2016 standard to allow a single point verification "if the temperature measuring device is used over a range of 10°C or less." The SIR is obsolete and can be removed from web when 2009 Standard is no longer in use.


Question: d) Temperature measuring devices shall be calibrated or verified at least annually. Calibration or verification shall be performed using a recognized National Metrology Institute traceable reference, such as NIST, when available.

Question: do reference thermometers need to be calibrated annually? These are traceable to NIST.

TNI Response:  As long as the reference thermometer is not being used as a piece of support equipment such as described in c, a reference thermometer is a reference standard as described in and would need to be calibrated before and after any adjustment, and in accordance with the lab’s documented procedure.


Question:  This section requires verification of volumes of volumetric dispensing devices (except Class A Glassware) if quantitative results are dependent on their accuracy.  Historically, this section has been interpreted to include disposable pipettes and plastic tubes used for measuring sample volumes or final volumes after digestion.  Section appears to require quarterly checks of these devices.  Quarterly checks seem excessive when the items are one use items.  Once per lot number seems more reasonable and would be similar to receiving a certificate from the manufacturer about the accuracy of a particular lot number.

TNI Response:  A verification of one pipette or tube per lot would meet the requirements.


Question:  Section states, "Volumetric dispensing devices (except Class A glassware and Glass microliter syringes) shall be checked for accuracy on a quarterly basis." Our laboratory analyzes VOCs in air and uses gas tight syringes up to 100 mL to prepare gas standards.  We are unsure of whether or not we must complete quarterly checks on these syringes. We're hesitant about using DI water to perform the quarterly checks on these syringes because they're used for preparing gas standards and we're unsure if moisture in the syringe would affect standard preparation.  We're also unaware of how we could complete the quarterly checks using air.  Our syringe vendor only offers a verification certificate for newly purchased syringes.  For these reasons, it may be impractical to complete quarterly checks. As I understand it, glass microliter syringes do not require quarterly checks because they deliver such a small volume that a quarterly check would be impractical.  Knowing this, if our 100 mL gastight syringes are similar in form (and from the same vendor) as our glass microliter syringes, would they require quarterly checks or not?  At a minimum is there any documentation we'd have to have on file for the syringes?

TNI Response:  If the syringe in question is neither Class A nor a glass microliter syringe, then it must be checked for accuracy on a quarterly basis. The laboratory must have documentation on file of this quarterly check.


Question:  The term "Microliter" is a trademark for Hamilton Company syringes. Are other brands and types of syringes acceptable, such as SGE MicroVolume, Hamilton GasTight, or Agilent syringes? If so, what is the definition of a glass microliter syringe (i.e. maximum volume, plunger construction, etc.). Thank you.

TNI Response:  The term “Microliter” is trademarked to a Hamilton syringe due to its capitalizing of the letter M. The Standard refers to microliter (uL) in the lower case of M. The Standard does NOT require a specific brand of syringe. As for what constitutes a microliter (uL) syringe, a syringe that is sold in terms of measuring in microliters (uL) is a microliter (uL) syringe.


Question:  The question relates to quarterly calibration verification of manual repeating pipettes where the settings on the mechanical device are (for example) 1-5 step-wise by 0.5, but these settings don't directly correlate to a volume dispensed. It is the choice of tip size used on the device that confers the volume dispensed based on a combination of the tip size and the selected setting on the device. (Here is an example device for reference -

Is it sufficient to verify the calibration of the device using the range of SETTINGS on the device and one tip size, or does the range of VOLUMES measured with the device and it's multiple tip sizes need to be used instead (which would necessitate using multiple tip sizes and possible difficulty hitting the midpoint range of BOTH settings and volumes)? It is our thought process that using the range of volumes instead of the range of device settings would be verifying both the tips and the device calibration at the same time instead of just the device calibration, while using the device settings would be verifying the calibration of just the mechanical device itself, about which this section is referencing.

TNI Response:  The standard requires the range of volumes be verified, including the mid-point of volume of the range of use. An appropriate tip for the volume dispensed must be used to verify the device at the lowest volume, the largest volume, and mid-point volume in the range of use.