Industries Information

 Syringes utilize a cylinder and plunger for precise delivery of liquids or gases in analytical, medical, pharmaceutical or biotechnology applications.  A syringe is a device used to inject medications or other liquids into body tissues or other media.  A needle is a slender hollow instrument for introducing material into or removing material from the body parenterally.  It is common for syringes to come with needles attached; it is not the rule, however.

The important parameters when specifying syringes are injection method, needle configuration, syringe volume, syringe scale graduations and pressure rating.  Syringes use one of two injections methods, manual or autosampler.  An injector is a mechanism for accurately injecting a predetermined amount of sample.  The injector can be a simple manual device, or a sophisticated autosampler that permits automated injections of many different samples into the liquid stream for unattended operation.  The needle may have one of two configurations if it is supplied with the syringe.  It may either be removable or fixed.  Syringe volume is the amount of sample the syringe can contain prior to injection.  Syringe scale graduations are the markings printed on the side of the scale for measuring the volume dispensed.  The pressure rating is the maximum pressure the syringe can withstand.

The important parameters when specifying needles are needle gauge, length, inner diameter and outer diameter.  When specifying a needle they range from largest to smallest, the larger the needle’s gauge, the smaller the needle. For example, a 4.0 gauge needle is larger (physical size) then an 8.0 gauge needle.  The important dimensions to consider for needles are length, inner diameter and outer diameter.  The outer diameter is dependent upon the gauge, but this is not true of the inner diameter.

Features common to syringes and needles include replacement needles included with the syringe, interchangeable plungers for the syringes, interchangeable barrels for the syringes, digital display and a Chaney adaptor, which provides a convenient method of performing multiple injections of the same volume of fluid without the need for careful reading of the syringe scale each time.

Pipettes and tips are used for accurate liquid handling in many lab applications. This area includes both pipettors, which are complete devices used to deliver a known quantity of solution to a vessel; and pipette tips, through which fluids are dispensed, which are often sold separately from the pipette or pipettor. Pipettes and tips are either of the classical style (glass) or digital.

There are three main types of pipettes and tips: positive displacement, air displacement, and Pasteur styles. Pasteur pipettes are small glass tubes with a bulb at the end used for dispensing small amounts of fluids. Positive displacement pipettes are used for high viscosity and volatile liquids. Both types of pipettes have a piston that moves in a cylinder, or capillary. In air displacement pipetting, a specified volume of air remains between the piston and the liquid. In positive displacement pipetting, the piston is in direct contact with the liquid.

Selecting air displacement pipettes and tips require special consideration. Air displacement pipetting, which is used for standard pipetting applications, is highly accurate. Even so, conditions such as atmospheric pressure, and the specific gravity and viscosity of the solution can have an effect on the performance of air displacement pipettes. Typically, air displacement pipettes are meant for general use with aqueous solutions.

Positive displacement pipettes and tips are used in applications that require extreme accuracy. These pipettes and tips are also recommended for specialized procedures such as DNA amplification. The microsyringe tips used in positive displacement pipettes are disposable, which helps avoid sample-to-sample and cross-contamination, and contamination due to the aerosol effect.  Positive displacement pipettes and tips are also used for high viscosity and volatile liquids.

Dispensers feed measured amounts of sample material into trays, vessels, microplates, or centrifuges, without human contact with the material. These devices may be operated manually, automatically timed, or computer controlled for more complicated projects.  Dispensers are used instead of simply pouring out materials because they are more accurate, help to cut down on waste, and lessen the risk of sample contamination.

The most common types of dispensers are bottle top and burette dispensers.   Bottle top dispensers portion out small volumes of sample from a bottle safely and reliably without contamination or waste.  Pouring introduces the possibility of contamination each time the bottle is opened and invariably leads to waste.  Burette dispensers are used for the volumetric transfer of reagents for titration.  They consist of a calibrated barrel, a delivery tip, and a valve (stopcock).  There are other far less common types of dispensers, but these tend to be designed for proprietary needs.

When determining which of the many dispenser types is best for a given set of applications, or expected uses, there are a number of criteria that should be specified.  It is important to be aware of the level of accuracy that will be needed.  Most dispensers function with a degree of accuracy between .5 to 1.0% of accepted values.  If the dispenser will be used in very sensitive tests, it may be better to tend towards those devices with a higher degree of accuracy.  Similarly, the volumetric increments to which the dispenser is geared will help to gauge its reliability for certain applications.  While milliliters are the most common increment, they are certainly not the only scale.  Additionally, it is important to be aware of the sample capacity of the device.  If the dispenser is going to be used often to produce or maintain reactions, especially in situations where it will not be directly supervised, or the experiment may take place over a period of days, a large capacity dispenser is suggested.

Diluters are used to simplify the process of sample preparation by diluting samples to standard concentrations. Most diluters come pre-programmed with standard (common) dilutions.  Common dilutions for concentrated samples are 1/4, 1/10, 1/25, 1/50, 1/100, 1/250, 1/500, 1/1000 and greater.  By using diluters, samples can be prepared in less time than standard manual methods, such as mixing solutions in a volumetric flask.  Diluters may also be used to make smaller quantities of a solution, when compared with other analytical techniques, such as atomic absorption spectrometry (AA), gas chromatography (GC), and high performance liquid chromatography (HPLC); thereby limiting solvent consumption and reducing overall waste and disposal costs.

When selecting between diluters, it is important to take the following specifications into account: accuracy, precision, solvent volume, and sample volume.  Accuracy describes the nearness of a measurement to the standard or true value, i.e., a highly accurate measuring device will provide measurements very close to the standard, true or known values.  Precision is the degree to which several measurements provide answers very close to each other. It is an indicator of the scatter in the data. The lower the scatter, the higher the precision.  Solvent volume is the amount of solvent (the substance that is used to dilute the sample) that the diluter can accept.  Generally, solvent volume needs increase, as concentration of the sample decreases.  Similarly, sample volume is the amount of sample material that diluters are designed to accept.

Once the diluters’ performance specifications are determined, the next step is to determine the display or interface options that best suit the given application.  Diluters are available with local interfaces or computer interfaces.  Local interface diluters should be selected if the device will be used for single batches, occasional operation, or if the sample preparation requires close supervision and alteration.  Local interface options include analog and digital panels for reaction information display and input.  Computer interfaces are appropriate for continuous batching of sample, preparations that require numerous steps, or long reaction times, or in laboratory settings where multiple activities are taking place.  Additionally, computer interfaces are useful if careful data tracking and logging is necessary, as well as remote display of data.

Autosamplers are automated sample loaders, usually robotic, used with chromatography, atomic absorption and other analytical technologies. Autosamplers are designed especially for laboratories that process large numbers of samples on a routine basis. They are used for a variety of tasks, ranging from general HPLC needs up to dedicated solutions for high sample throughput.  Most are designed to interface with PC systems, and some autosamplers can be remotely computer controlled.  Complete remote control of all operational parameters such as injection time, number of injections per vial, rinses, three auxiliary contact closures, and internal injection valve actuation are available by means of optional serial or parallel interfaces.

Autosamplers may use a variety of receptacles to accept sample or reagent injection. These include simple vials, wellplates, or graphite furnace sample cups.  Wellplates, also known as microplates, are plastic plates or cassettes containing a specified number (typically 96 or 384) of small wells arranged in rows.  Researchers commonly use them to conduct numerous chemical reactions at the same time. Graphite furnaces are used in atomic absorption spectroscopy to atomize a sample.  The sample crucible is usually a cup cut from hollow aluminum or magnesia tubing.  Syringes or injector valves are the usual methods used to inject materials into the testing receptacles. Some varieties of autosamplers are specifically configured for one type of receptacle platform, while others can use them interchangeably.

Autosamplers are used in a wide variety of applications.  These can range from analysis of Organic Volatile Impurities (OVIs), plastics, polymers, blood alcohol analysis, and flavors, to semiconductor applications and any ultratrace analysis of commonly occurring elements. Clinical applications including drinking water testing, wastewater analysis and reclamation projects, soil composition, toxicity analysis.  In addition, a range of QA/QC control procedures, such as the EPA protocols, can be automated using the optional Intelligent Sequencing Software.