Analytical Letters 

About: Analytical Letters is an academic journal published by Marcel Dekker. The journal publishes majorly in the area(s): Detection limit & High-performance liquid chromatography. It has an ISSN identifier of 0003-2719. Over the lifetime, 10255 publications have been published receiving 116227 citations. The journal is also known as: Chemical analysis & International journal for rapid communication.

Spectrophotometric Determination of Nitrate with a Single Reagent

Abstract: A spectrophotometric procedure for determination of nitrate in water, soil extracts, and a variety of other sample types is described using one reagent solution which is easily prepared and stored. Sample and equipment requirements are minimal. Reduced chemical hazard, simplicity, and versatility represent improvements over existing methods. Limit of detection is 0.01 µg N mL−1 (0.72 μM ) or less, depending on the matrix.

Electrochemical biosensors: recommended definitions and classification*

Abstract: *A special report on the International Union of Pure and Applied Chemistry, Physical Chemistry Division, Commission I.7 (Biophysical Chemistry), Analytical Chemistry Division, Commission V.5 (Electroanalytical Chemistry).

Fluorescence Quantum Yields of Tryptophan and Tyrosine

Abstract: Fluorescence quantum yields (Q) for tyrosine, tryptophan, and phenylalanine in water at 23° determined by the comparative method using a quinine standard were found to be 0.14, 0.13, and 0.024, respectively. Similar values were obtained with phenol as the standard. The numbers are much lower than those literature values which have been widely used to calculate protein fluorescence quantum yields. Possible reasons for the discrepancies are discussed. The quantum yields of isomeric tyrosines and fluorophenylalanines are also reported.

Two-Point Calibration of Circular Dichrometer with d-10-Camphorsulfonic Acid

Abstract: The circular dichroism (CD) of d-10-camphorsulfonic acid (CSA) in terms of ∊L - ∊R is 2.36 and -4.72 cm2 mmol−1 at 290.5 and 192.5 nm, respectively. The corresponding molar ellipticities, [⊝], are 7,800 and -15,600 deg cm2 dmol−1. A ratio of -2.00 for the negative and positive bands provides a simple two-point calibration. If a standardized spectropolarimeter is available, the ratio of [⊝]290.5/[M]306 = 1.75 to 1.76 or [⊝]290.5/([M]306−[M]270) = 0.77 at the extrema is recommended for CD calibration at the 290 nm region, which is unaffected by the presence of optically inactive impurities such as water. Alternately, CSA has a molar absorption coefficient of 34.5 cm2 mmol−1 at 285 nm, which can be used for concentration determination. This leads to (∊L−∊R)290.5/∊285 = 0.068 or [⊝]290.5/∊285 = 226. However, CSA must be purified to remove any impurities that are optically active or absorb light or both in the UV region.

An Electrochemical Detector for Liquid Chromatography with Picogram Sensitivity

Abstract: A simple liquid chromatograph with an extremely sensitive electrochemical detector is described. The detector, which can be constructed for lees than $5.00 (excluding electronics), has an actual dead volume of < 1 μl and operates well in the 50–100 picogram region. Routine quantitative work at the 5–10 nanogram level is described. Potential applications to the analysis of biogenic amines are discussed.