Author Archives: Rachel Kohn

About Rachel Kohn

So how did an MIT Ph.D. end up selling refrigerators? When I figured out that a lot more scientists buy lab refrigerators than innovative leading-edge instruments. I hope that my many years of lab experience will help you find the right equipment for your work. Before co-founding Tovatech I worked in business development and project management at Smiths Detection, Photon-X, Cardinal Health, and Hoechst Celanese. And before that I spent 12 years as an R&D chemist at Hoechst Celanese and Aventis working on advanced drug delivery systems, polymer films and membranes, optical disks, and polysaccharides. Some day, eventually, I’ll make enough money to develop an innovative technology that will change the world.

Selecting and Using Precision Scale Test Weights

Calibrating Scales with Test Weights

Weighing accuracy is a primary criterion for precision scales, analytical balances and moisture analyzers where readout (the smallest weight difference displayed) and linearity (the ± deviation from the actual weight) are governed by GLP, ISO and other standards.  Test weights have a critical role to play when scales  with capacities from milligrams to tons are not automatically internally (see below) calibrated . The type of calibration, whether internal or external, is indicated on scales’ spec sheets.… Read the rest

How to Pick the Best Ultrasonic Cleaner

Selecting the Best Ultrasonic Cleaner

Among the steps to be taken to pick the best ultrasonic cleaner is a thorough understanding of what the process is to accomplish and then identify ultrasonic cleaner features that let you accomplish the task(s) in the most cost-effective way.  While ultrasonic cleaners are available from a variety of manufacturers and across a broad spectrum of prices, your investment must be based on an assurance that it will accomplish your task(s) quickly and efficiently.  When you do this you’ll be able to identify your best ultrasonic cleaner.

In other words, pick the ultrasonic cleaner you need.  Don’t succumb to “keeping up with the Joneses.”

An Important Ultrasonic Cleaner Priority:  Size

You can’t mount a 19-inch tire on a 15-inch wheel.  Similarly the dimensions (length, width, depth) of the ultrasonic cleaner’s tank must be sufficient to accommodate the largest component you plan to clean.  But there’s more:  Because a majority of … Read the rest

Selection Tips for Precision Digital Scales

10 Selection Tips for Precision Digital ScalesToday’s precision digital scales, also referred to as digital balances, perform a broad range of weighing-related functions in R&D, quality control, and similar applications where accuracy and precision are key criteria to meeting government, trade association, and industry-promulgated standards.  For purposes of discussion this post focuses on weighing equipment used in comparatively protected environments vs. scales found on manufacturing floors, shipping and receiving departments.  Let us hasten to add, however, that the need for precision and accuracy is important for any application, and equipment is available to meet required standards regardless of where scales are employed.

Precision and Accuracy Defined

Certain of our posts discussing precision digital scales and analytical balances harp on an important difference between precision and accuracy as selection criteria.  Allow us to cite an example:  A $5,000 wristwatch may be precise, but if the hands are set wrong it does not show the accurate time.  More … Read the rest

Analytical Balance Recalibration – A Critical Exercise

analytical balance calibrationAccuracy and precision (there is a difference) in the performance of analytical balances are crucial when weighing extremely small masses such as to 0.1 or 0.01 mg.  Even the smallest deviation in accuracy can throw off critical measurements when compounding, for example, pharmaceuticals and weighing active pharmaceutical ingredients (API).  For this reason analytical balance recalibration exercises and procedures should be carefully spelled out in a company’s standard operating procedures.

The Effect of Gravity on an Analytical Balance

Manufacturers of analytical balances such as the Kern line available from Tovatech call attention to the importance of calibration and recalibration early in their instruction manuals.  Kern points out, for example, that gravitational pull varies throughout the world due to the fact that the world is not a perfect sphere.  This was demonstrated a few years ago by shipping the Kern Gnome to many locations around the world.  The Kern Gnome was accompanied … Read the rest

Ultrasonic Cleaning Solutions Selection Guidelines

ultrasonic_cleaing_solution_selection_v3

Successful ultrasonic cleaning procedures are most likely achieved when thought is given to ultrasonic cleaning solutions that deliver the desired results.  Just as you notice the plethora of detergent choices on supermarket shelves so too is the vast variety of ultrasonic cleaning solution chemistries available to satisfactorily accomplish your cleaning tasks.

In fact an improper choice of cleaning solution chemistry (just as the wrong ultrasonic frequency*) can damage parts or surfaces being cleaned.

Most but not all ultrasonic cleaning solutions marketed today are in the form of biodegradable concentrates formulated for specific cleaning tasks.  They are shipped with instructions regarding dilution, recommended cleaning temperatures and material safety data sheets (MSDS).   Container volumes vary by manufacturer; 2.5, 10 and 25 liters are typical examples.  Biodegradable formulas eliminate handling, health and disposal concerns associated with trichloroethylene and perchlorethylene solvents formerly used for ultrasonic cleaning.… Read the rest

A Vaccine Refrigeration Specification Guide     

Vaccine Refrigeration - 10 Essential Items to ConsiderProper vaccine refrigeration is not a hit-or-miss proposition.  Each year there are reports on how improper vaccine storage or other mishaps relating to vaccines result in loss of potency.  This necessitates locating and revaccinating those who have received compromised inoculations plus the associated cost and inconvenience.  Proper vaccine storage is also a critical element for complying with government-funded Vaccines for Children (VFC) programs.

Vaccine manufacturers are careful to note the proper storage temperatures for their products along what is called the cold chain of custody between manufacturing and inoculation.  But manufacturers have little influence on the equipment used by healthcare facilities to maintain these temperatures.  The CDC (Centers for Disease Control and Prevention) has stepped into this by issuing its 2016 Vaccine Storage and Handling Toolkit to provide comprehensive information on this vital activity.    The Toolkit also covers in detail the importance of staff training and written standard operating procedures … Read the rest

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 Check Moisture Content in Soybeans

Check Soybean Moisture Content

Soybeans and a product.

The U.S. Soybean Export Council says the most important storability factor in soybeans is soybean moisture content with recommended content based on end use of the product.  Examples include ≤ 11% for direct food use or seed, and 12.5-13% for solvent extraction.  Average moisture above 13% can lead to quality deterioration in a relative short time span.  Moisture content in soybeans can be quickly spot-checked with a benchtop moisture analyzer such as the MLS 50-3D available from Tovatech.

Benchtop moisture balances are widely used in many industries to check or confirm that moisture content meets specifications.  Excess moisture can lead to spoilage in grain products, for example. When products are sold by weight customers are paying for water rather than product.  When content is too low quality can also be affected and buyers get more than they pay for.

How Moisture Analyzers Work

A benchtop moisture … Read the rest

Stability Testing for Temperature and Humidity

Stability Testing for Temperature and Humidity

Stability Testing

24 cu. ft. Nor-Lake temperature & humidity test chamber

Stability testing is a critical part of drug and medicinal product development to determine the shelf life of such products under a variety of environmental conditions such as temperature and humidity.  Family prescriptions likely have on their label a recommended “use by” date and notification if special storage conditions should be observed. The regulatory mandate for stability testing in the United States is contained in 21 CFR Part 211 Section 166.

Tests to determine storage requirements and shelf life for drugs and other medicinal products are taken under a variety of imposed and tightly controlled environmental conditions.  Because testing time can be extensive accelerated studies are permitted to support tentative expiration dates provided full shelf life studies are being conducted.

 

Temperature and Humidity Test Chamber Specs

Stability testing is performed in specially designed test … Read the rest

Blood Storage Refrigerator Specifications

The Norlake undercounter blood bank refrigerator with temperature chart recorder.

The Norlake undercounter blood bank refrigerator with temperature chart recorder.

The Code of Federal Regulations CFR 640.4 (h) provides guidelines for blood storage immediately after collection.  Unless it is to be further processed, blood storage should be at temperatures between 1 and 6⁰C.   Blood storage refrigerators should be designed in such a way to maintain these tight temperature tolerances.  Added useful capabilities are alerting personnel in the event of temperature excursions and automatically recording the unit’s internal temperature for record keeping.

Examples of Blood Bank Refrigerators

Examples of scientific refrigerators ideal for blood storage are Nor-Lake units available from Tovatech.  These auto-defrost units range in size from a 4.2 cubic foot, 4-drawer undercounter unit to 1, 2  and 3-door upright models with 24, 33, 52 and 80 cubic feet of storage capacity.  These refrigerators meet AABB, ANRC and FDA requirements

All models feature glass doors to facilitate content monitoring and … Read the rest