Mark Electronics

Suffern, NY, United States

Mark Electronics

Suffern, NY, United States
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Mark H.,Mark Electronics | Workman J.,Unity Scientific LLC | Workman J.,University of San Diego
Spectroscopy (Santa Monica) | Year: 2015

The science of statistics are concerned with the effects of the random portion of the uncertainty, not least because it can help discern and, even better, calculate the systematic errors so that they can be corrected. Over the years, statisticians have discovered much about the nature and behavior of random errors, and have learned how to specify bounds for what can legitimately be said about the data that are subject to these errors. One of the more important findings is that if the data are subject to fluctuations because of random error, then anything you calculate from those data will also be subject to fluctuations. To the statistician, a value calculated from a set of data subject to random fluctuations is what is known as a statistic. An important difference between samples and statistics is the distribution of the variations. The distribution of values of multiple measurements from a sample, or the distribution of values of measurements from multiple samples can be almost anything, and is determined by the physics or chemistry (or other applicable discipline) of the situation governing the behavior of the samples.


Mark H.,Mark Electronics | Workman Jr. J.,University of San Diego | Workman Jr. J.,Liberty University
Spectroscopy (Santa Monica) | Year: 2012

The Classical Least Squares's spectral results were examined at a different laboratory by David Heaps of AstraZeneca, along with his colleague Kelly Sill-Drahos to verify that the original results obtained were not spurious. Besides the differences in equipment, there were some other minor differences between the two experiments. Measurements were performed using both a 2-mm pathlength sample cell and a 1-mm sample cell. Samples were made up by volume percent rather than weight percent. The first set of samples used samples measured out to the weight values specified in the original experiment. The second laboratory used chloroform instead of dichloromethane, because chloroform was available. It is clear that in the 4000-5000 cm-1 region, most of these samples are completely absorbing, so it was necessary to edit out the 4000-4500 cm-1 spectral region.


Workman J.,Unity Scientific LLC | Workman J.,University of San Diego | Workman J.,Liberty University | Mark H.,Mark Electronics
Spectroscopy (Santa Monica) | Year: 2014

Photometric accuracy and precision, as reproducibility and repeatability, respectively, are essential for building consistent large databases over time for use in qualitative searches or quantitative multivariate analysis. If the spectrophotometer in use is inconsistent in terms of linearity and photometric accuracy, the analytical precision and accuracy will be jeopardized over time. Photometric accuracy and linearity drift over time within a single instrument or between instruments and create errors and variation in the accuracy of measurements using databases collected with different photometric registrations. How do current commercial instruments vary with respect to photometric accuracy and precision over time? What are potential solutions to this challenge? © 2014, Advanstar Communications Inc. All rights reserved.


Mark H.,Mark Electronics | Bradley M.,Thermo Fisher Scientific
Spectroscopy (Santa Monica) | Year: 2015

Howard Mark and Mike Bradley presented an overview of spectroscopic instrumentation in 2015. The majority of the spectroscopic instrumentation products were presented at Pittcon 2015 in New Orleans, Louisiana, US. Howard Mark and Mike Bradley continued the practice of providing additional details about all the products in a series of appendixes. The development of specialpurpose analyzer was one of the emerging trends in spectroscopic instrumentation during the conference.


Mark H.,Mark Electronics | Workman Jr. J.,Medical Device Industry
Spectroscopy (Santa Monica) | Year: 2010

Several algorithms that are commonly used for analyzing data and especially those used for multivariate calibration are discussed. The relationship between the absorbance and analyte concentration can be found using least squares calculations such as the multiple linear regression (MLR). The classical least squares (CLS), inverse least squares (ILS), algorithms apply least squares calculations to the spectral data. The concentration of the components of a mixture based upon first principles such as the principal of absorbance being proportional to concentration, in accordance with Beer's law. The multiple linear regression (MLR) requires external reference laboratory values for the concentrations, while CLS requires spectra of the pure mixture components.


Mark H.,Mark Electronics | Workman Jr. J.,Unity Scientific LLC
Spectroscopy (Santa Monica) | Year: 2013

The results we found from our previous subseries about classical least squares analysis provides the mechanism for understanding when and why calibration transfer can be done easily or when it will be difficult. Those results also provide a basis for a modified understanding of what calibration transfer means and how we can tell whether or not such a transfer can be performed, for any given analysis.


Mark H.,Mark Electronics
Spectroscopy (Santa Monica) | Year: 2014

A comprehensive review of spectroscopic instrumentation presented at Pittcon 2014 is presented. Andor Technology had a deep-depletion detector for their NIR cameras. Axiom showed extensions of measurement capability for mid-IR, near-IR, and Raman probes including extended length and extended temperature and pressure capability. FiberTech Optica presented a probe incorporating integral optical filters. Harrick had a multiple-reflection attenuated total reflectance (ATR) accessory that can measure samples in the 2-20 μL range. Gasera showed a specialized photoacoustic detector for detecting cocaine in hair. Shimadzu displayed an entry in a different race: one for the fastest mass-spectral acquisition, with an instrument that can measure spectra at a speed of 30,000 u/s. Agilent presented a handheld instrument designed to measure samples in situ. Anasys promoted the highest spatial resolution instrument. Bruker combined a mid-IR and NIR detector with a wide-band beamsplitter in its interferometer to enable simultaneous measurements in both spectral regions.


Mark H.,Mark Electronics
Spectroscopy (Santa Monica) | Year: 2010

Standard comparison of two methods, Bland-Altman Plot and Tukey Mean-Difference Plot involves regression plots of reference (X) versus test (Y) values and residual plots showing the errors (or differences) between the two methods. The Bland-Altman graphic consists of a residual or difference plot showing the mean of Method A and B for each sample analysis (X) versus the difference for Method A minus Method B for each sample analysis (Y). A good agreement between the methods is demonstrated by differences (residuals) near zero, or with a set of differences with nearly identical bias values for all sample analyses. The Tukey Mean-Difference plot (identical to the Bland-Altman plot) is more common for engineering research than for medical literature (10). It is exactly the same as the Bland-Altman plot but uses different X- and Y-axis labels, such as mean and difference.


Mark H.,Mark Electronics
Spectroscopy (Santa Monica) | Year: 2012

A review of the products introduced at the 63rd Pitconn 2012 (Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy) is discussed. CEM Corporation displayed MARS 6, which is a microwave sample digestion. It has a one-touch programming, automatic recognition of vessel type and number, automatic determination of all the parameters necessary for complete reaction. Cetac Technologies introduced XLR-8, an extended rack autosampler, whose features include unattended operation, easy setup, and self-cleaning. FiberTech Optica launched miniature fiber optic Raman probe with internal filtering. The line of Raman probes is a new products for FTO, featuring proprietary optical design and internal filtering for improved signal collection efficiency. The probe is designed for laboratory use. PerkinElmer presented Optima 8×00 Series ICP-OES spectrometers. It is a benchtop, dual-view spectrometer delivering superior detection limits and true simultaneous measurements, using half the argon of traditional systems with no loss in performance.


Mark H.,Mark Electronics
Spectroscopy (Santa Monica) | Year: 2011

Howard Mark and Jerome Workman, Jr., share their views on the connection between the mathematics of classical least squares (CLS) and the graphical displays that are conventionally used to present it. They have found that the absorbances of the various materials when added together wavelength by wavelength give the absorbances of the mixture. This process ties together the absorbances of the three different materials in a mathematical sense. The concentration of the materials in the mixture is exactly the information which they want to derive from the analysis. It is observed that this concentration is exactly the result of performing the least-squares calculations using the spectra of the pure materials against the spectrum of the mixture. Howard Mark and Jerome Workman, Jr also note that the information required by them is derived from the calibration calculations when they perform them the CLS way.

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