Dispatches from Pittcon 2018 in Orlando

Leco to ‘transform’ carbon and nitrogen analysis

By Joseph James Whitworth contact

- Last updated on GMT

Mason Marsh, organic product manager for Leco at Pittcon 2018
Mason Marsh, organic product manager for Leco at Pittcon 2018
Leco has launched two instruments for carbon and nitrogen analysis in food, feed and agricultural samples.

The 828 series has macro sample mass capability and cycle times of three minutes as well as a reduction reagent tube lifetime of 4,000 samples and a reagent-free furnace.

The 928 series includes macro sample mass of up to 3g and cycle analysis times of five minutes as well as a 100-sample position autoloader for analysis in a variety of organic materials.

Carbon and nitrogen analysis

Mason Marsh, organic product manager for Leco, said the 828 series will be launched in Q2 this year.

“Nitrogen analysis is important for food and feed because it is how total protein is calculated in the products,” ​he told FoodQualityNews at Pittcon.

“In the past total protein may have been calculated via wet chemistry. Today the market is moving towards combustion instruments that deliver faster results for total nitrogen and then a multiplier is used to calculate protein, the multiplier is typically a 6.25 multiplier to do total protein.

“Carbon is more of an agricultural measurement, typically organic fertilisers or you are looking for decomposition of an agricultural product like residues or waste materials, they are going to break down and reduce nitrogen, carbon is a good indicator of how that will work.”

Marsh added there is generally a 10-12 week lead-time from receipt of order.

“We released the FP928 and 828 which is the nitrogen only model and there will be a release in the future of a CHN model – carbon, hydrogen and nitrogen – that particular model is targeted towards the materials and energy market for solid fuels and we are targeting to release that in Q4 2018.”

The 828 series has kept the core capabilities of previous units and improved throughput, said Marsh.

“We are down to three minute analysis now which gives us throughput of 20 samples per hour. We have also put a lot of emphasis on better uptime. The two playing together is better all around. Generally all the reagent replenishment cycles are double what they were from the previous units.”

Bigger samples in 928 series

The 928 series was released late last year but shown for the first time at Pittcon and units are shipping to end users.

“It is also a carbon nitrogen or nitrogen only for the same kind of markets, food and feed, its big difference is its sample size,”​ said Marsh.

“The 828 is geared towards a 200-600 milligram sample that fits most needs for most applications, the 928 allows us to go up to 2 or 3g of analysis. That overlaps with the sample size that is more traditional,​ the wet chemistry method, and it delivers sample representation that was needed for difficult samples that have problems with homogeneity, like a soil or a meat.

“The big difference is the furnace design, it is designed to handle those bigger samples. The loader has a bigger capacity but the things I talked about with the 828 as far as speed of analysis and uptime, we did the same design. The 828 is the fastest as it takes three minutes, the 928 takes five minutes so is slower but when you think about the difference of a half gram sample and a 3g sample, that is a significant difference in mass so the difference in time is related to capabilities in mass.

“There will be one other model (of the 928) we release in the future and it will be the CNS – a carbon, nitrogen and sulphur - instrument. That model is targeted for the agronomy and agriculture markets for fertilizers and soils and plant tissues. Carbon, nitrogen and sulphur in the plant tissue and the soil tends to be an indicator of fertilisation need and requirements as well as plant health.”

Automated moisture analysis

Leco also unveiled a thermogravimetric moisture system – the TGM800 – that can measure up to 16 samples at a time with drying time end-point recognition.

It is applicable for sample matrices including food, feeds, milled products and agricultural materials.

Moisture is one of the paramount analyses for any organic material that contains moisture, said Marsh.

“Typically, constituent analysis, whether it be carbon, nitrogen, fat or protein is calculated on a dry basis. To correct for a dry basis calculation for what your constituent is you need to know the moisture content,” ​he said.

“Moisture content ends up being important for almost all samples and it is one of those analyses that is relatively simple but at the same time is relatively complex as there is not really a clear standard for it. So, what we’ve done with the TGM800 is we’ve given a precision automated unit to the marketplace that uses a gravimetric loss on drying.

“There are two primary methods for moisture, especially for foods and feeds, and that is either an air oven that is a loss-on-drying method where a sample is placed in an oven for a fixed period of time, placed in a desiccator, taken out, final weight and the difference is calculated it is moisture.

“The other one would be a Karl Fischer and that is more of a liquid application so it is more specific but it is a primary method.”

Fixed time and constancy drying

The TGM is an automated method to replace primary methods for loss-on-drying.

“There is less operator involvement, we don’t have desiccators now, the operator is not moving samples around. One measurement is taken via the operators involvement, the automation takes care of the rest of the mass measurements. It is a thermogravimetric analysis where we have sequential weights taken during the drying period.

Marsh said it can support fixed time drying and constancy drying.

“Meaning you can set a method based on a fixed time or when the sample reaches a plateau of mass constancy. So it optimises your drying time and ensures your sample is actually dry, you are not just assuming after an hour or two hours it is dry,” ​he said.

“Food companies will often look at stability, microbial interaction and requirements around product for certificate of analysis, so it has to be less than 10%, more than 20%.

“The thing we see most as far as wide use of moisture analysis is more on calculating dry basis constituents for other analysis. If the sample has inherent moisture in it, it can change moisture levels based on conditions such as ambient humidity.

“So if you did a round robin analysis, where you sent a sample and split it to five different labs in the US, depending on where they are, the sample could weigh differently because of the moisture content. The only way to get that result to be a apples-to-apples comparison is to normalise it against a dry basis.”

Increase productivity and efficiency

Marsh said industry is interested in increasing productivity and efficiency in labs and one of the easiest ways is to automate systems.

“This particular automation in moisture analysis is quite a leap, it is about reducing points of error and getting an accurate value. Not only are we looking at productivity, efficiency and workflow in the laboratory so you can do more with less people or have the same amount of people do better things with their time but you also reduce a lot of error in this analysis,” ​he said.

“The feature that allows us to do automated drying and ensure that the drying time is accurate as far as all the samples in the batch have reached constancy is something that will improve speed, throughput and accuracy of the samples.

“If you had a sample that didn’t release moisture as readily or was higher in moisture, that feature for constancy would keep that sample drying until it reached a definition in the method.”

Related topics: Food Safety & Quality

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