News from LabRulezICPMS Library - Week 53, 2025

Our Library never stops expanding. What are the most recent contributions to LabRulezICPMS Library in the week of 29th December 2025? Check out new documents from the field of spectroscopy/spectrometry and related techniques!

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This week we bring you application notes by LECO, Metrohm and Shimadzu!

1. LECO: Determination of Nitrogen/Protein in Cheese

• Application note
• Full PDF for download

Protein is one of the most significant nutrient components in cheese. The accurate and precise determination of protein not only plays a role in the characterization of the nutritional value of cheese but is also key in determining the economic value of different cheeses. A rapid and precise method for the determination of total protein in cheese provides a vital quality and process control procedure. 

Protein in cheese is most commonly calculated using the measured total Nitrogen content in the sample and a multiplier or protein conversion factor (typically 6.38). Protein conversion factors vary depending on the sample matrix. Nitrogen determination in organic materials is performed using either a classical wet chemical method (Kjeldahl), or a combustion method (Dumas). The Kjeldahl method involves sample digestion, distillation, and ammonia determination typically by titration. This method involves time-consuming sample preparation and the use of hazardous materials. The LECO FP928 is a Nitrogen determinator that utilizes an automated combustion (Dumas) method and provides accurate and precise results in approximately five minutes. This eliminates involved sample preparation and the use of hazardous materials resulting in a rapid, cost-effective method for the quality control of cheese production. 

Instrument Model and Configuration 

The FP928 is a macro combustion Nitrogen/Protein determinator that utilizes a pure Oxygen environment in a high-temperature horizontal ceramic combustion furnace, utilizing ceramic boats designed to handle macro sample masses (~1.0 g). A thermoelectric cooler removes moisture from the combustion gases before they are collected in a ballast. The gases equilibrate and mix 3 in the ballast before a representative aliquot (3 cm or 3 10 cm volume) of the gas is extracted and introduced into a flowing stream of inert carrier gas (Helium or Argon) for analysis. The aliquot of gas is carried through a heated reduction tube, filled with Copper, to convert Nitrogen Oxide combustion gas species (NO2) to Nitrogen (Nx). The aliquot gas is then carried to a thermal conductivity cell (TC) for the detection of Nitrogen (N2). Thermal conductivity detectors work by detecting changes in the thermal conductivity of the analyte gas compared to a reference/carrier gas. The greater the difference between the thermal conductivity of the carrier gas and the analyte gas, the greater the sensitivity of the detector. The FP928 supports either the use of Helium or Argon as the instrument's carrier gas. When used as a carrier gas, Helium provides the highest sensitivity, and the best performance at the lower limit of the Nitrogen range. The thermal conductivity difference between Argon and Nitrogen is not as great as the thermal conductivity difference between Helium and Nitrogen; therefore, the detector is inherently less sensitive when using Argon as a carrier gas.

Analysis Considerations 

The combustion of cheese samples with a high-fat content can result in some degree of sooting. The primary filter tube (glass and steel wool) should be monitored for signs of sooting. If soot is observed in the glass and steel wool within the primary filter tube, reduce the sample mass to prevent this soot build-up, and change the glass and steel wool as necessary. The combustion of cheese samples can also result in the formation of salts; therefore, it is important to monitor the primary filter tube for signs of excessive corrosion of the steel wool and change it as necessary (approximately every 50 cheese samples). In addition, the autoloader arm should be inspected and cleaned on a regular basis when analyzing cheese products.

2. Metrohm: Analysis of fabric softeners and laundry perfumes with NIR spectroscopy

Determination of dry matter, pH, and viscosity in seconds

• Application note
• Full PDF for download

Fabric softeners and laundry perfumes (concentrated fragrances) are a category of personal care/laundry products used for their ability to make textiles softer, smoother, and more pleasantly scented after the washing cycle. A variety of raw materials is necessary to manufacture these products, and different analytical methods are often required before production can commence. Traditional analysis requires time-consuming methods. This Application Note describes how viscosity, dry matter content, and pH level of fabric softeners and laundry perfumes are measured with near-infrared spectroscopy. Nearinfrared spectroscopy (NIRS) is a fast, chemical-free analysis technique for quality control of fabric softeners and laundry perfumes without sample preparation.

EXPERIMENTAL EQUIPMENT 

Fabric softener and laundry perfume samples were measured with an OMNIS NIR Analyzer Solid (Figure 1) in transflection mode (1000–2250 nm) using a 1 mm gap size reflector and 28 mm disposable vials. Reference values of dry matter were measured by loss on drying, and pH and viscosity were determined with a pH meter and viscometer, respectively. OMNIS Software was used for all data acquisition and prediction model development.

RESULT

The obtained NIR spectra (Figure 2) were used to create prediction models for quantification of dry matter, pH value, and viscosity. The quality of the prediction models was evaluated using correlation diagrams (Figures 3–5) which display a very high correlation between the NIR prediction and the reference values. The respective figures of merit (FOM) display the expected precision of a prediction during routine analysis.

CONCLUSION

This Application Note shows the feasibility of the analysis of dry matter, pH, and viscosity in laundry perfumes and fabric softeners with near-infrared spectroscopy. Measurement of all three quality parameters can be conducted within seconds without using any chemicals. NIRS can be used in several steps of the production chain or during quality control of the final product, saving manufacturers time and money. Additionally, with NIRS only one technology is required, compared to the standard analytical techniques often used for these determinations (Table 1).

3. Shimadzu: Content Analysis of Heavy Metals in Soil by ICP-MS

• Application note
• Full PDF for download

User Benefits

• High-sensitivity analysis at less than 1/100 of Japan’s soil content standard is possible.
• Correction methods and H2 reaction conditions reduce interference from rare earth elements when measuring As and Se.
• Variation in measurement sensitivity due to the soil matrix is small, enabling stable measurement even when measuring multiple samples over a long time.

Soil pollution occurs when chemical or hazardous substances in the soil harm the environment and human health. Soil pollution may be caused by natural phenomena, but most is caused by human activities such as leakage of hazardous substances from industrial activities and improper disposal of waste.

In Japan, soil surveys are conducted in accordance with the Soil Contamination Countermeasures Act to prevent harm to human health. These surveys are mandatory when facilities using specified hazardous substances are decommissioned or when the characteristics of land over a certain size have changed. Two types of tests are conducted: soil leaching tests and soil content tests. Soil leaching tests are conducted to evaluate the risk of ingesting groundwater containing hazardous substances leached from the soil, and soil content tests are conducted to evaluate the risk of directly ingesting hazardous substances from the soil through the mouth or skin. The number of such soil surveys is increasing year by year, and since many samples need to be analyzed simultaneously, even in laboratories that accept them, stable and robust analysis equipment isrequired. 

In this Application News, soil content tests were conducted on five types of soil samples using an ICPMS-2050. The results of the validity of the analysis, the influence of interference from rare earth elements (REE), and long-term stability are also presented.

Conclusion 

Soil content tests were conducted using the ICPMS-2050. The measurement sensitivity was 1/100 or less of the soil content standard, and the validity of the measurements was shown by recovery tests, which confirmed that the influence of the matrix was minimal. Interelement correction and half-mass correction are effective for interference from REE, and the correction method can be selected depending on the measurement requirements. Furthermore, it was shown that for Se measurement, the interference from Ar and Gd can be largely eliminated by using H2 reaction conditions. Regarding long-term stability, the variation of the measurement sensitivity was small, and the quantitative values remained stable even when high-matrix samples derived from soil were repeatedly measured. Furthermore, by using the advance rinse function, the sample introduction volume can be reduced, shortening measurement times and improving stability