List of Articles in the Category Flow Meter

How to Check Pump System Accuracy for HPLC Analysis

Digital HPLC Liquid Flow Meter At a GlancePump system accuracy is crucial for equipment used to conduct high performance liquid chromatography (HPLC) analysis in the pharmaceutical and other industries subject to regulatory oversight by the FDA and similar authorities. Among functions performed by HPLC are included checks for purity, monitoring changes in pharmaceutical intermediates during chemical synthesis scale-up, stability and dissolution tests, and performing ongoing quality control procedures.

A Brief on HPLC Analysis

Identifying an analyte by HPLC is based on accurate and reproducible column retention time as the analyte is pumped through an HPLC system.  Reproducible retention time is critical and depends on accurate, uniform, reproducible HPLC pump flow rates.

Note that it is important to distinguish between accuracy and precision.  These two terms may seem the same but they are not necessarily so.  For example, an HPLC system (or for that matter many other systems such as analytical scales) may test out as precise.  This … Read the rest

How to Simplify Accuracy Checks on HPLC Pump Systems

The compact FlowCal 5000 flowmeter and thermal printer

The compact FlowCal 5000 flowmeter and thermal printer

Eluent passing through HPLC pump systems can, over time, impact the accuracy of the system and result in inaccurate flow rates.  HPLC pump system impellers, valves, seals, injectors and other components in direct contact with analytes carried in an eluent are subject to wear as well as possible deposition of damaging salts and other substances that interfere with flow rates.

That’s why HPLC pump system flow rates should be checked on a regular basis.  Regular accuracy checks contribute to meeting FDA standards for system OQ and PQ validation as well as ongoing performance verification.  There are different ways to do this.  One we call the hard way, the other the easy way.

An example of the hard way is repeatedly and manually collecting and measuring by weight or volume the solvent as it exits the HPLC system.  This is extremely work-intensive and … Read the rest

Digital HPLC Flowmeter Accuracy Checks

Flow CalAs pointed out in our post on HPLC pump accuracy uniform and reproducible column retention times are critical when analytes are pumped through a high performance liquid chromatography system. One of the most efficient ways of checking on the accuracy of HPLC pump systems is the Flow Cal 5000 digital liquid flow meter available from Tovatech. But how do you check on the accuracy of the checker – namely the Flow Cal 5000?

Flow Cal 5000 HPLC Flow Meter Accuracy Checks

When received from Tovatech the Flow Cal 5000 is accompanied by a UKAS traceable calibration certificate* good for one year. Standard calibration is 1 ml/min but on request it can be supplied at points from 0.5 to 25 ml/min. Multiple readings are taken at each flow rate then averaged on the calibration certificate.

A recalibration procedure should be scheduled annually or immediately if users think the unit is not … Read the rest

Monitoring Options for HPLC Pump Systems

An HPLC Pump System

An HPLC Pump System

High performance liquid chromatography is an exacting process in the pharmaceutical and related fields subject to FDA and other regulatory oversight.  HPLC pump systems are complex in design.  Many such systems may be in operation at a single facility; all require periodic flow rate monitoring to identify solvent flow rate inconsistencies that could lead to costly product rejections.  Determining flow rate accuracy and precision is part of the HPLC system operational qualification (OQ).

Manual HPLC Flow Analysis

One manual way to check the accuracy of HPLC pump flow rates is called the volumetric method.  It requires, in addition to patience and sharp eyesight on the part of the technician, a stop watch and a finely graduated cylinder.  The technician begins collecting HPLC eluent in the graduated cylinder and immediately starts the watch.  When sufficient volume is collected (the amount depending on internal operating procedures*) the technician … Read the rest

How to Minimize HPLC Pump System Problems

William Tell demonstrated accuracy and precision – as should an HPLC pump system.

William Tell demonstrated accuracy and precision – as should an HPLC pump system.

High performance liquid chromatography requires extremely accurate pumping systems delivering an accurate, precise and pulse-free flow of the mobile phase.  An HPLC pump system is a complex device with multiple moving parts subject to wear.   Standard operating procedures should be in place to both minimize wear such as caused by particulate matter settling in valves and other components, and having spares on hand to replace components subject to wear (i.e. valves, piston and piston seal components).  As one of many maintenance steps it is always a good idea to flush your HPLC system with rinse solvents after analysis with buffered mobile phases.

HPLC Pumping System Problems are not Uncommon

A review of the literature discloses that pumping system malfunction ranks high as the cause of incorrect readings.  We will not go into detail here other than to … Read the rest

How to Read an HPLC Flowmeter Calibration Certificate

Pharma labs regularly employ HPLC

Pharma labs regularly employ HPLC

Accuracy checks on high performance liquid chromatography (HPLC) pump systems should be performed frequently as part of a laboratory’s standard operating procedures.   Uniform and reproducible retention time is extremely important and relies on uniform and reproducible HPLC pump flow rates.

Checking the accuracy of an HPLC system can be done manually – an extremely time consuming and laborious process – or by using the digital FlowCal 5000 liquid flowmeter from Tovatech.   But as we’ve noted in a companion post on traceable calibration flowmeters themselves must be periodically checked for accuracy.

This too is a time-consuming and laborious process involving multiple measurements and calculations for each flow rate being tested.  That’s why we strongly recommend returning the FlowCal 5000 to us on an annual basis to have it tested in conformance to UKAS standards and returned with a calibration certificate traceable to the UKAS (United Kingdom … Read the rest

Understanding Traceable Calibration

HPLC Flow Meter mounted on a bottle

HPLC Flow Meter mounted on a bottle

Tovatech’s FlowCal 5000 HPLC liquid flow meters are shipped with traceable calibration documentation attesting that the equipment accurately displays a flow rate of 1.0 milliliters per minute along with other flow rates from 0.05 to 25.00 ml/min as requested by the customer, all within ±1% of the actual flow rate.  The purpose of these flowmeters is to check the accuracy of HPLC pumping systems.

HPLC pump system accuracy checks are only as good as the flowmeters that test them.  This means that initially and periodically flowmeters should be tested for accuracy according to recognized standards.

Flow Meter Traceability Explained

Traceability in this instance is defined as an unbroken record of documentation affirming the performance of a particular piece of equipment – in this case the FlowCal 5000 HPLC liquid flow meter. Documentation is provided by calibration laboratories using testing equipment certified to be … Read the rest

A Primer on HPLC Flowmeters

The FlowCal 5000 Digital Liquid Flow Meter

The FlowCal 5000 Digital Liquid Flow Meter

High performance liquid chromatography – HPLC – is very often the method of choice for analyzing pharmaceutical compounds starting with R&D and continuing into manufacturing.  Among other things it is used to

  • Check candidate drugs for purity
  • Monitor changes in pharmaceutical intermediates during chemical synthesis scale up
  • Test the stability and dissolution of formulations in development and
  • Support quality control in final drug products

Identifying an analyte by HPLC is based on accurate and reproducible column retention time as it passes through an HPLC system.  Reproducible retention time is critical and depends on uniform, reproducible HPLC pump flow rates.  A leak developing or other malfunction in the HPLC system will result in analysis errors.  Obviously, then, continuous testing is necessary to insure that the HPLC system is properly calibrated.  This is called operational qualification. OQ starts before the HPLC system is put into … Read the rest

HPLC Flow Meter Calibration & Recalibration

First of all, our HPLC flow meters are shipped factory calibrated along with an accompanying calibration certificate for a flow rate of 1.0 ml/min plus additional flow rates requested by the customer. The calibration certificate certifies that the displayed flow rate is within ±1% of the actual flow rate at each calibration point.

Calibration points recorded on the certificate are not based on single measurements. Instead they result from an extensive process aimed at achieving statistically accurate data by taking, for example, 30+ readings at 0.5ml/min, 40+ readings at 1.0ml/min and ~100 readings at 5.0ml/min. Data are captured and averaged via an RS 232 interface to a PC. The certificate shows the average of these readings at each flow rate. The percent error and percent standard deviation from the actual flow rates are also calculated from these averages and shown on the certificate.

The actual flow rate is determined gravimetrically, … Read the rest

Navigating Quality Management Systems

With continuous press reports on product recalls ranging from automobiles to pharmaceuticals to baby cribs, quality management (QM) takes on every greater importance for company management, its personnel, customers and shareholders regardless of size, product or service.  The cost of product recalls in terms of lost revenues, reputation and lawsuits – let alone loss of life or health – presents a strong case for strong quality management systems in any company.

QM systems can be broadly divided into quality practices and quality standards.  Learn which of these apply to your organization.  Compliance procedures should be carefully spelled out in your company’s operation manual.  Record-keeping is crucial.  These must be maintained in a safe location and accessible by qualified third parties.

Some Examples of QM Practices

Here are some examples of QM practices.  Detailed information on these and others is available on the Internet.… Read the rest