Was Crocodile stronger at Marineford? Or was he holding back in Alabasta?

 During the Alabasta arc, Crocodile displayed a level of power that was initially considered overwhelming by the Straw Hat Pirates. He possessed the Logia-type Devil Fruit called the Suna Suna no Mi (Sand-Sand Fruit), which granted him the ability to control and transform into sand. He had a reputation as a Shichibukai and controlled the desert kingdom of Alabasta from the shadows. His strength was showcased through his battles with Luffy and others. At Marineford, Crocodile was present as part of the war that took place at Marine Headquarters. While he did participate in the battle, he didn't display the same level of dominance as some other powerful characters present. This has led fans to speculate that he might not have been as strong as initially portrayed in Alabasta. It's important to note that power scaling and character abilities can be subject to interpretation and development by the author. Oda often keeps details deliberately open-ended to keep the story intriguing.

What is spectophotometry? What is its application?

 Spectrophotometry is a analytical technique that involves the use of a spectrophotometer, a device that measures the intensity of light as it passes through a sample, to determine the concentration of a particular substance in a solution.

Spectrophotometry works by measuring the amount of light that is absorbed or transmitted by a sample at a particular wavelength. The absorption or transmission of light by a sample is influenced by the presence of certain substances, and by measuring the amount of light absorbed or transmitted at different wavelengths, it is possible to determine the concentration of those substances in the sample.

Spectrophotometry has a wide range of applications in various fields, including chemistry, biology, and medicine. It is often used to measure the concentration of specific substances in a solution, such as enzymes, proteins, and other biomolecules. Spectrophotometry is also used to analyze the purity of substances and to identify unknown substances. In addition, spectrophotometry is used in environmental testing to measure the concentration of pollutants in water, soil, and air.