Nearly every chemist begins his or her path under the guidance of trained professionals, learning the correct way to implement the scientific method and to handle themselves safely in the laboratory. I am no different—I obtained my doctorate in Analytical and Environmental Chemistry several years ago. In the early 2000's, I worked in the environmental analysis sector investigating soil contamination due to heavy metals and chemical spills, measuring water quality, and especially performing studies relating to atmospheric chemistry. During these years, I’ve been exposed to several analytical technologies, varied laboratory sizes, and different sample preparation procedures.
A common theme runs throughout these different places—the hunt for more time and a bigger budget. However, with the right tools at your disposal, you can have your cake and eat it, too.
Environmental chemical analysis
The focus of environmental analysis lies in these three major sectors:
It is in our best interest to study these interconnected areas as thoroughly as possible, considering how our health and the future of our species heavily relates to and relies upon them.
Authorities and regulations
With that in mind, local and governmental authorities have developed and enforced several regulations for the good of public health.
One of the more well-known authorities on the subject is the United States Environmental Protection Agency (EPA). Under the Clean Air Act (enacted in 1970) and Clean Water Act (1972), as well as the requirement to report the use and disposal of toxic chemical substances (TRI reporting), several norms and standards have been developed over the intervening years to meet the stringent guidelines brought forth in these and other regulations.
In the world of water analysis, one of the most common methods you will hear about is EPA Method 300. The methods 300.0 and 300.1 give detailed instructions to chemical analysts regarding measurement of common anions (Part A) and inorganic disinfection byproducts (Part B) in water via ion chromatography.
Interested in EPA Method 300.1? Enjoy a free selection of our related IC application notes below:
Heavier workloads = less time per sample
A growing list of aqueous contaminants and increasingly stringent regulatory requirements require labs to process more samples in less time, without sacrificing accuracy.
The nature of the samples measured in environmental laboratories is such that sample preparation is required—this always involves filtering the samples, and in many cases diluting them as well. This procedure is the only way to prevent damage to the analysis system and to achieve accurate results.
However, sample preparation is an expensive step, as it involves a significant amount work as well as costly consumables.
Time to crunch the numbers!
A 30 day study was performed on a Metrohm IC system with automatic ultrafiltration and dilution by an environmental analysis laboratory in the US. This lab, like many others, processes a high volume of samples, including some with a limited shelf life. Reliability is therefore a particularly important criterion when it comes to buying a new system.
Economic considerations also play a key role: a new system should pay for itself as quickly as possible; it needs to be generating a return on investment after a year at the latest.
All aqueous environmental samples must be filtered prior to analysis. This prevents particles from the sample contaminating or blocking the separation column, significantly extending its lifetime. The high volume of samples at the lab involved in this study drove material cost down to only $1 USD per syringe filter. However, since each individual sample requires a new filter, with 14,300 samples a year this still amounts to $14,300 – just for filtration materials!
The integrated ultrafiltration in the ion chromatography system from Metrohm only needs one filter change per day, saving this laboratory over $12,000 per year. What’s more, the ultrafiltration process is fully automated.
Compared to manual filtration, this saves three minutes of working time per sample. With labor costs of $18 per hour, this again corresponds to savings of around $13,000 per year.
Suppression reduces the conductivity of the eluent, resulting in a more sensitive conductivity detection of the analyte. This makes it possible to achieve particularly low limits of detection and quantification.
The instrument previously used at this laboratory (from a different supplier) employed membrane-based suppressors. These suppressors have to be replaced every three months, costing approximately $1,200 each time. The Metrohm Suppressor Module (MSM), on the other hand, is a one-off purchase because it utilizes ion exchanger particles in a robust micro-packed bed for suppression instead of membranes. The three suppression cartridges of the MSM alternate between suppression, rinsing, and regeneration, thereby ensuring continuous suppression at all times.
The regeneration reagents are inexpensive, averaging $52 per 1,000 samples, resulting in total annual costs of $750 for 14,300 samples. This is much cheaper than the cost of replacing a membrane suppressor multiple times!
With Metrohm columns, the environmental laboratory in this study achieved better separation of the analytes and a much longer column service life – on average, 7,000 injections compared to 1,200 with the previous columns. There appear to be two factors that are key to the reduced wear on the separation column:
- The Metrohm ion chromatograph provides measuring signals that are four to five times stronger. This makes it possible to reduce the injection volume by a factor of five.
- Additionally, Metrohm Inline Ultrafiltration removes particles down to a size of 0.2 μm, whereas manual filtration with syringe filters can only remove particles down to 20 μm.
Overall, using Metrohm separation columns saves nearly $18,000 in one year for a high-throughput environmental analysis laboratory.
If the determination indicates that the analyte concentration is too high, i.e., outside the permissible determination range, the sample must be diluted and reanalyzed.
This is the situation for around 30% of the samples at the laboratory involved in this study. Manual dilution takes the lab staff at least three minutes per sample. With labor costs of approximately $18 USD per hour, this adds up to annual costs of $3,800.
Automatic Inline Dilution eliminates this expense: the analysis system dilutes the relevant samples fully automatically and then measures them again. This makes the laboratory much more efficient: the daily sample throughput increases, and samples with a limited shelf life are always analyzed in good time.
Find out more about the many different Metrohm Inline Sample Preparation options available here:
Significant cost savings weren’t the only benefit of the Metrohm analysis system – the 30 day comparison study also revealed a number of other advantages. The company was impressed with the robustness of the instrument and with its ability to measure the entire range of samples processed in their laboratory.
Its stable calibration also made it possible to reduce the calibration frequency: the new system only needs calibrating every two to three weeks instead of every two to three days.
The most impressive features, though, were the high measuring sensitivity and the large linear range of the detector. Thanks to the latter, only 2% of the samples remain outside the measuring range and have to be diluted – compared to 30% with the old system.
The 30 day test proved to the lab in question that the Metrohm IC with the integrated automatic inline sample preparation techniques saves both material and labor costs. Furthermore, it also offers a number of improvements in terms of analysis performance compared to the systems previously used on site.
The most significant savings are those for labor and material costs as a result of using ultrafiltration, followed by those resulting from the longer service life of the separation column.
For the final savings calculation over an entire year, download our White Paper on the subject below.