A low-cost automated titration system for colorimetric endpoint detection.

An auto titrator system was developed to accurately and precisely detect colorimetric endpoints for spectrochemical titrations. This system was constructed using inexpensive components such as a Raspberry Pi® single-board computer, 3D-printed components, and a commercially available spectral sensor. The auto titrator was evaluated by performing a standard method for determination of water hardness. Regardless of analyst experience, the auto titrator performed better than the traditional titration approach that involves manual dosing of titrant and visual detection of the endpoint. Inter-day, intra-day, inter-instrumental, and intra-instrumental validation studies were performed to establish the accuracy and precision of endpoint detection. The auto titrator eliminates the subjective bias in color perception and produces accurate and precise endpoint results.

Oral Administration of Nicotinamide Mononucleotide Increases Nicotinamide Adenine Dinucleotide Level in an Animal Brain.

As a redox-sensitive coenzyme, nicotinamide adenine dinucleotide (NAD+) plays a central role in cellular energy metabolism and homeostasis. Low NAD+ levels are linked to multiple disease states, including age-related diseases, such as metabolic and neurodegenerative diseases. Consequently, restoring/increasing NAD+ levels in vivo has emerged as an important intervention targeting age-related neurodegenerative diseases. One of the widely studied approaches to increase NAD+ levels in vivo is accomplished by using NAD+ precursors, such as nicotinamide mononucleotide (NMN). Oral administration of NMN has been shown to successfully increase NAD+ levels in a variety of tissues; however, it remains unclear whether NMN can cross the blood-brain barrier to increase brain NAD+ levels. This study evaluated the effects of oral NMN administration on NAD+ levels in C57/B6J mice brain tissues. Our results demonstrate that oral gavage of 400 mg/kg NMN successfully increases brain NAD+ levels in mice after 45 min. These findings provide evidence that NMN may be used as an intervention to increase NAD+ levels in the brain.

A device for fully automated on-site process monitoring and control of trihalomethane concentrations in drinking water.

An instrument designed for fully automated on-line monitoring of trihalomethane concentrations in chlorinated drinking water is presented. The patented capillary membrane sampling device automatically samples directly from a water tap followed by injection of the sample into a gas chromatograph equipped with a nickel-63 electron capture detector. Detailed studies using individual trihalomethane species exhibited method detection limits ranging from 0.01-0.04 µg L(-1). Mean percent recoveries ranged from 77.1 to 86.5% with percent relative standard deviation values ranging from 1.2 to 4.6%. Out of more than 5200 samples analyzed, 95% of the concentration ranges were detectable, 86.5% were quantifiable. The failure rate was less than 2%. Using the data from the instrument, two different treatment processes were optimized so that total trihalomethane concentrations were maintained at acceptable levels while reducing treatment costs significantly. This ongoing trihalomethane monitoring program has been operating for more than ten months and has produced the longest continuous and most finely time-resolved data on trihalomethane concentrations reported in the literature.

A fully-automated analyzer for determining haloacetic acid concentrations in drinking water.

A fully-automated, on-line, real-time analyzer has been developed for preconcentration and analysis of haloacetic acids (HAAs). Preconcentration of HAAs is achieved by sample acidification and solid phase extraction onto a hydrophobic polymeric resin using sequential injection analysis (SIA). The HAAs preconcentrate is then analyzed using post-column reaction-ion chromatography (PCR-IC), which is selective for HAAs. Systematic optimization of SIA preconcentration parameters are described followed by detailed method detection limit (MDL), accuracy, precision, and linearity studies. MDL values for the individual HAA9 species range from 0.4 to 0.9 µg L(-1). Side-by-side comparison studies of HAAs analysis in 14 real-world drinking water samples from Alabama, Arkansas, Kentucky, Minnesota, Missouri, Mississippi, New York, Pennsylvania and Tennessee are presented that compare the optimized SIA-PCR-IC to USEPA Method 552.3. Trace levels of HAAs detected in select samples are reported, and the bias values calculated between the two methods are typically less than 5 µg L(-1) for eight of the nine individual HAAs.

Analysis and Confirmation of 1,3-DMAA and 1,4-DMAA in Geranium Plants Using High Performance Liquid Chromatography with Tandem Mass Spectrometry at ng/g Concentrations.

1,3-Dimethylamylamine (1,3-DMAA) is a stimulant commercially sold in a variety of dietary supplements as a chemical species derived from geranium plants (Pelargonium graveolens). Whether 1,3-DMAA naturally occurs in geranium plants or other dietary ingredients, it has important regulatory and commercial ramifications. However, the analysis of 1,3-DMAA in geranium plants is not trivial due to low concentrations and a complex environmental matrix, requiring high selectivity and sensitivity. An extraction method combined with high performance liquid chromatography and tandem mass spectrometry is used to determine 1,3-DMAA and 1,4-dimethylamylamine (1,4-DMAA) concentrations in geranium plants with both external calibration and standard addition method. Samples from the Changzhou, Kunming, and Guiyang regions of China during both winter and summer were analyzed for 1,3-DMAA and 1,4-DMAA. The diastereomer ratios of the 1,3-DMAA stereoisomers of a racemic standard and the extracted plant were also quantified.

A single automated instrument for monitoring total trihalomethane and total haloacetic acid concentrations in near real-time.

A single instrument is presented for selectively measuring the concentrations of total trihalomethanes (THM4) and total haloacetic acids (HAA9) directly from drinking water distribution systems. The method is based on the fluorescence reaction of THM4 or HAA5 species with nicotinamide. The method detection limit (MDL) for THM4 was 2.5 microg L(-1) with mean % recovery of 108% and % relative standard deviation (% R.S.D.) of 4%. For HAA5, the MDL was 3.3 microg L(-1) with mean % recovery and % R.S.D. of 102% and 3.5%, respectively. Side-by-side comparisons to United States Environmental Protection Agency methods (Methods 502.2 and 552.3) in chlorinated and chloraminated distribution systems exhibited reproducible biases that ranged from approximately 0.2 to 5 microg L(-1) for THM4 and from approximately -0.7 to -27 microg L(-1) for HAA5. The device provides for automated on-line sampling and analysis of THM4 and HAA9 with hourly sample analysis rates and is effectively a real-time system for drinking water monitoring.

On-line monitoring of nine haloacetic acid species at the microgL(-1) level using post-column reaction-ion chromatography with nicotinamide fluorescence.

A laboratory-built automated instrument is reported for on-line, near real-time monitoring of nine haloacetic acids species (HAA9) in drinking water. The device uses anion-exchange chromatography to separate the HAA9 species, followed by post-column reaction with nicotinamide in basic solution with fluorescence detection. Method detection limits for HAA9 species ranged from 0.6 to 10.1microgL(-1), mean % recovery values ranged from 58 to 161%, and % relative standard deviation ranged from 3.5 to 32% while operating within a factor of 2.5-5 of the method detection limit. The bias between the proposed method and United States Environmental Protection Agency Method 552.3 was measured during two separate on-line studies and using grab samples collected from different distribution systems. In general, the two methods showed good agreement with biases for HAA9 of less than 10microgL(-1).

On-line monitoring of microg/L levels of haloacetic acids using ion chromatography with post-column nicotinamide reaction and fluorescence detection.

A method for measuring the concentrations of the five regulated haloacetic acids (HAA5) in drinking water is reported. This method uses ion chromatography to separate HAA5 species, followed by post-column reaction with nicotinamide and detection of the fluorescent products. The result of method detection limit, accuracy, precision, linearity and interference studies are reported. The on-line monitoring method is compared directly to USEPA 552.3 in Memphis drinking water. Though not meant to replace the USEPA 552.3 for compliance monitoring, the proposed method does offer attractive alternatives considering the ease of automation and application of on-line monitoring directly from drinking water distribution systems.